f:2 0 o:!- = o 0 _ an - an -,...._ -('I')

- ('I') TABLE OF CONTENTS

LIST OF TABLES . iii LIST OF FIGURES viii LIST OF PLATES . x ACKNOWLEDGEMENTS xii IN MEMORIUM . . . . xiii INTRODUCTION . . . 1 History of Commercial Harvests in Alaska 1 History of Toxicity Problems in Alaska 7 RAZOR CLAM BIOLOGY ...... 33 Distribution of Razor Clams in Alaska 33 Razor Clam Life History Studies . 36 Methods ...... 36 Sexual Characteristics . 4 2 Spawning ...... 46 Growth Rates . . . . 61 Age-length-weight Relationships . 80 Population Dynamics and Habitat Relationships . 87 Frequency of Occurrence by Tide Level . . 87 Estimated Upper Habitable Tide Levels . . 119 Apparent Affects of Substrate and Exposure on Razor Clam Survival and Density on the Low Tide Terrace 119 Age by Tide Level ...... 125 Total Valve Length by Tide Level . . . . 128 Growth Increment in Valve Length by Tide Level. 128 Fecundity ...... 132 Mortality and Survival ...... 135 Negative and Positive Relocation of Marked Razor Clams. 138 Genetics and Larval Drift . 140 SURVEY TECHNIQUES ...... 144 Density Indicators ...... i 44 The Little Mummy Island Study . . 144 The Point Steele Beach Study . . . 156 Methods of Estimating Clam Numbers . . 159 Employment of Density Indicators and Probability Distributions ...... 159 Stratified Random Sampling . . . . 1 70 Probabilities and Reapportionment . 173 Mark and Recapture . 178 Beach Surveys ...... 181 Dredging ...... 185 APPLICATION OF DISCRIMINATORY AND SEQUENTIAL ANALYSES AS AN ADJUNCT TO THE SHELLFISH SANITATION PROGRAM . . 189 Discernment of Annuli ...... 189 The Problem of Approved and Unapproved Growing Areas . . 190 Analysis of an Anticipated Typical Case . . . . 1 90 Examples of High Risk and Low Risk Areas ...... 192 SUMMARY ...... 199 APPENDIX 1: Age and length of razor clams dug commercially during 1969 and 1970 in the Cordova, Alaska, growing areas ...... 202 APPENDIX 2: Identification and description of razor clam study plot sites in Cordova Sector I 214 APPENDIX 3: Growth rate of razor clams collected from a variety of growing areas in Alaska . . . . 228 APPENDIX 4: Method of total estimation for a stratified sampling scheme when two subestimates are combined within 1000 sq. ft. (92.9 m2) index blocks ...... 25 4 APPENDIX 5: Gamma distribution fitted to Point Steele Beach "C" plot series razor clam abundance by tide level ...... 256 APPENDIX 6: Analysis of substrates obtained fr om Cordova and Polly Creek razor clam growing areas . 257 APPENDIX 7: Test results of razor clam growth increment in valve length by tide level . . . . 265 APPENDIX 8: Method for determining fecundity in razor clams . 269 APPENDIX 9: Life tables ...... 270 APPENDIX 10: Expansion of variance equations and propagation of error formula for application in estimating population size by employment of density indicators and probability distributions . 284 GLOSSARY ... . 285 BIBLIOGRAPHY. . 286

ii LIST OF TABLES

Table 1. Commercial razor clam harvest history for the Cordova, Alaska, area 1916 to 1973 . . . . 9 Table 2. Comparative history of razor clam production in the Cook Inlet and Kodiak Island areas based on the standard case of forty-eight 1/2-pound cans or pounds (#) where indicated . . . . . 15 Table 3. Sex ratio of mature razor clams from eight study plot sites in Orca Inlet, Cordova Sector 1 . . . . 44 Table 4. Comparative growth of males versus females in Cordova Sector 1 for members of the 1963 cohort 45 Table 5. Analysis of age, length, sexual maturity and related dimorphism for razor clams in Cordova Sector 1 ; length measured at the last annulus formation...... 47 Table 6. Analysis of age, length, sexual maturity and related dimorphism for razor clams in Cordova Sector 4; length measured at the last annulus formation...... 48 Table 7. Five levels of gonad pH in the razor clam, Cordova, Alaska, May to September, 1973 . 60 Table 8. Estimated probable range of razor clam spawning threshold (accumulation of 1350 temperature units from January 1) in the Cordova, Alaska, growing areas...... 63 Table 9. Analysis of variance of razor clam length (mm) at the sixth annulus ( 1963 cohort) from Strawberry Reef, Softuk Beach, Katalla Beach and Kanak Island (outside beach) ...... 65 Table 10. Analysis of variance of razor clam length (mm) at the sixth annulus ( 1963 cohort) from Inside Ocean Bar, Southwest Ocean Bar, Strawberry Reef, and Kanak Island (outside beach) ...... 66 Table 11. Analysis of variance of razor clam length (mm) at the sixth annulus (1963 cohort) from Inside Ocean Bar (lOB), Southwest Ocean Bar (SWOB), Erickson Bar (EB), Canoe Pass Trail Bar (CPTB), tittle Mummy Island Bar (LMIB), and Rockslide Bar (RB) ...... 67 Table 12. Analysis of variance of razor clam length (mm) at the sixth annulus ( 1963 cohort) from Erickson Bar, Little Mummy Island Bar, Canoe Pass Trail Bar, and Rockslide Bar ...... 68 Table 13. A comparison of the mean length at the sixth annulus utilizing razor clams from Concrete Bar, Cordova Sector 1; Polly Creek Beach, Cook Inlet; and Swikshak Beach, Alaska Peninsula...... 69 Table 14. 10 - 90 percentile range of razor clam annual ring lengths from plots 2, 3, 4, 5, 6, 7, 9 and 10 in Cordova Sector 1...... 70

iii Table 15. 10 - 90 percentile range of razor clam annual ring lengths from Strawberry Reef, Softuk Beach, Katalla Beach, and Kanak Island in Cordova Sector 4 ...... 71 Table 16. Composite analysis of the first order of recruit razor clams from Cordova Sectors 1 and 4 as applied to the present legal size of 4 inches

(102 mm) in valve length ...... 72 Table 17. 80 percent average length of razor clams from Cordova Sector I and data for fitting a Walford line to length ...... 74 Table 18. 80 percent average length of razor clams from Cordova Sector 4 and data for fi tting a Walford line to length ...... 7 5 Table 19. Standard mean length of razor clams from Polly Creek, west side of Cook Inlet, and data for fi tting a Walford line to length ...... 78 Table 20. Standard mean length of razor clams from Swikshak Beach, Alaska Peninsula, and data for fitting a Walford line to length ...... 81 Table 21. Length-weight relationship of razor clams in Cordova Sector I collected during 1971 . 83 Table 22. Length-weight relationship of razor clams in Cordova Sector 4 collected during 1971 . 84 Table 23. Distribution of dug razor clams by plot per tide level ± mean lower low water from eight study sites in Sector I, Cordova, Alaska, 1969...... I 07 Table 24. Distribution of dug razor clams by age per tide level ± mean lower low water from eight study sites (data lumped) in Sector I, Cordova, Alaska, 1969...... 108 Table 25. Analysis of covariance to test for a difference in means (percent razor clams per tide level transformed by an arcsin square root transformation) and whether one regression line can be used for all observations from the +4 to the +I foot (+1.22 to +0.30 m) tide level among eight study sites in Sector l, Cordova, Alaska ...... 109 Table 26. Analysis of covariance to test for a difference in means (percent razor clams per tide level transformed by an arcsin square root transformation) and whether one regression line can be used for all observations from the 0 to the -3 fo ot (0 to -0.91 m) tide level among five study sites in Sector I, Cordova, Alaska...... II0 Table 27. Distribution of razor clams by tide level ± mean lower low water fr om "C" series study plots at Point Steele Beach, Hinchinbrook Island, Cordova, Alaska, growing area, 1971 ...... 112 Table 28. Distribution of razor clams by tide level ± mean lower low water from Katalla and Softuk beaches, Cordova Sector 4, 1971...... 114

iv Table 29. Analysis of covariance to test for a difference in means (percent razor clams per tide level transformed by an arcsin square root transformation) and whether one regression line can be used for all observations from the +3 to the +1 foot (+0.91 to +0.30 m) tide level as pertains to sampling data of (1) Orca Inlet study sites; (2) Point Steele Beach II C11 series plots; (3) Katalla- Softuk beaches; and ( 4) the gamma distribution derived from Point Steele 11 C11 plots ...... 115 Table 30. Analysis of covariance to test for a difference in means (percent razor clams per tide level transformed by an arcsin square root transformation) and whether one regression line can be used for all observations from the 0 to the -2 foot (0 to -0.61 m) tide level as pertains to sampling data of (1) Orca Inlet study sites; (2) Point Steele Beach II C11 series plots; (3) Katalla-Softuk beaches; and ( 4) the gamma distribution derived from Point Steele 11 C11 plots ...... 116 Table 31. Regression estimates of razor clam frequency of occurrence by tide level on the low tide terrace derived from a gamma distribution fitted to Point Steele Beach II C11 series plot data, Cordova, Alaska ...... 117 Table 32. Extrapolation of the Point Steele Beach 11 C11 plot series gamma distribution of razor clam density by tide level from the low tide terrace to subtidal depths, Cordova, Alaska ...... 118 Table 33. Estimated upper habitable tide level (relative to mean lower low water) at various razor clam growing areas based on the ratio of the uppermost habitable tide level at Cordova, Alaska ( +4. 50 feet), and the mean tide level at Cordova, Alaska ( +6.40 feet) ...... 120 Table 34. Analysis of substrate obtained from Point Steele Beach, Cordova Sector 1, 1971, from +5 to -16.5 feet (+1.52 to -5.03 m) relative to mean lower low water...... 122 Table 35. Analysis of substrate obtained from Swikshak Beach, Alaska Peninsula, September, 1970, at tide levels estimated to be between mean lower low water and the + 3 foot ( +0. 91 m) tide level ...... 1 23 Table 36. Mean diameter of sand obtained from the mean lower low water level of several razor clam beds in the Cordova area during 1971, and the resultant proportions of fines, silts, and clays ...... I 26 Table 37. Relationship between the density of ]-year-old razor clams per 5 sq. ft. (0.46 m2) at mean lower low water and the mean percent of fine substrate (0.005 mm at the same datum plane for seven growing areas in Cordova Sector 1...... 127

v Table 38. Analysis of variance of razor clam age (years) by tide level as determined from study plots in Cordova, Alaska, Sector 1, 1969 ...... 129 Table 39. Regressions of razor clam age and total valve length by tide level as determined from study plots in Cordova, Alaska, Sector I, 1969 ...... 130 Table 40. Analysis of variance of unweighted razor clam total valve length (mm) by tide level as determined from study plots in Cordova, Alaska, Sector I, 1969 ...... 131 Table 41. Calculated weight loss during the spawning period of razor clams fr om July 5 to July 24, 1971, in Cordova Sector I ...... 133 Table 42. Razor clam fecundity estimates fr om Copalis Beach, Washington, 1939, and Cordova, Alaska, 1971 136 Table 43. Survival rates of razor clams in the growing area of Cordova, Alaska ...... 139 Table 44. Variables and codes that were recorded along with "show" values of marked razor clams at Little Mummy Island, Cordova Sector 1 ...... 148 Table 45. An individual summary of the 35 surviving razor clams that were observed at Little Mummy Island, Cordova Section I, from June 29 to September 15, 1970, for determination of density indicators...... 149 Table 46. \'ariables entered into a computer for a step'vvise regression analysis to determine razor clam density indicators relative to periods of observation ...... 151 Table 47. Conversion table for maximum water vapor pressures in millibars from temperatures in Fahrenheit used to obtain the water vapor deficit...... 153 Table 48. Calculations using mean "show" as an indicator of clam density: (a) Analysis of variance of the nine variables selected from the stepwise regression for determining expected mean show; (b) the regression of razor clam density indicators to determine expected mean show; and (c) the regression to convert expected mean show to the percent of razor clams showing ...... 154 Table 49. How clam show is affected when one of the included variables is increased by one standard deviation and the ranked importance of the variables ...... 155 Table 50. Comparison of observed and calculated number of razor clams with reference to the known location of 35 marked specimens from the Little Mummy Island study, Cordova, Alaska ...... 161 Table 51. Raw data from field notes for a population estimate of dug razor clams at Big Point Bar, Cordova, Alaska, 1971 ...... 162 Table 52. Population estimate of dug razor clams at Big Point Bar, Cordova, Alaska, 1971, utilizing probabilities and density indicators ...... 165

vi Table 53. Estimated age-density structure of dug razor clams at Big Point Bar, Cordova, Alaska, 197 1 168 Table 54. Raw data fo r the Big Point Bar screening, July 9, 1971, Cordova, Alaska ...... 174 Table 55. Estimated number of 1-year-old razor clams within a 150-foot ( 45.72 m) wide corridor, from upper to lower tide levels, at Big Point Bar, July 9, 1971, using the stratified random sampling method ...... 175 Table 56. Population estimate of screened razor clams at Big Point Bar, Cordova, Alaska, July 9, 1971, using probabilities and reapportionment from samples obtained at mean lower low water ...... 176 Table 57. Population estimate of screened razor clams at Big Point Bar, Cordova, Alaska, July 9, 1971, using probabilities and reapportionment from samples obtained at the 0, +0.30, and +0.61 m tide levels ...... 179 Table 58. Method for allocation of sampling effort for razor clams in mark and recapture studies . . 182 Table 59. Results of subtidal dredging for razor clams, Boswell Bay to Egg Island Channel, Cordova Sectors I and 2, July, 1971...... 188 Table 60. Operating characteristics for accepting lots of razor clam shellstock of different quality 195 Table 61. Results of discrilninatory analysis applied to various razor clam growing areas in Alaska 197

vii LIST OF FIGURES

Fig. 1. Razor clam growing areas of Cordova, Cook Inlet, and Swikshak ...... 8 Fig. 2. Trend of razor clam production, Cordova, Alaska, 1916-1963 ...... 14 Fig. 3. Cordova Sectors 1 and 2 with razor clam sampling stations designated ...... 21 Fig. 4. Cordova Sector 4 with razor clam sampling stations designated ...... 23 Fig. 5. Razor clam sampling stations located at the east side of Cook Inlet ...... 24 Fig. 6. Razor clam sampling stations located at Polly Creek Beach, west side of Cook Inlet . . . . 25 Fig. 7. Razor clam sampling locations at the Swikshak growing area, south side of Alaska Peninsula . . 27 Fig. 8. Geographic locations of known razor clam growing areas in Alaska ...... 30 Fig. 9. Razor clam growing areas of Cordova, Alaska, Sectors 1 and 4 ...... 43 Fig. 10. Percent of razor clams that had not begun to spawn at time t. 50 Fig. 11. Percent of razor clams that were actively spawning at time t. 51 Fig. 12. Percent of razor clams that were completely spawned at time t...... Fig. 13. Change in weight by time period for razor clams at specific valve lengths collected from Cordova Sector 1, 1971 ...... 53 Fig. 14. Change in weight by time period for razor clams at specific valve lengths collected from Cordova Sector 4, 1971 ...... 54 p· � lg. 15. Comparison of seawater temperatures in the Cordova area during 197 1...... 56 Fig. 16. Five levels of hydrogen ion concentration (pH) in the gonad of razor clams from Cordova, Alaska, Sectors 1 and 4 and their relationship to the sequence of spawning...... 59 Fig. 17. Means and standard deviation of seawater temperatures collected at the Cordova, Alaska, tide station for the period 1949 to 1973 ...... 62 Fig. 18. Growth of razor clams from Cordova Sector 1 . 76 Fig. 19. Growth of razor clams from Cordova Sector 4 . 77 Fig. 20. Growth of razor clams from Polly Creek Beach 79 Fig. 21. Growth of razor clams from Swikshak Beach. 82 Fig. 22. Age-length-weight relationship of razor clams collected from Canoe Pass Trail Bar, Cordova Sector 1, October 5, 1971 ...... 85 Fig. 23. Age-length-weight relationship of razor clams collected from Cordova Sector 4, August 7, 1971 . 86 Fig. 24. A comparison of usable weight to total weight for razor clams collected from Cordova Sector 1, 197 1 ...... 88

viii Fig. 25. Divisions of a typical beach ...... 95 Fig. 26. Basic structure of foreshore ...... 96 Fig. 27. Comparison of a general gamma distribution curve fitted to Point Steele Beach, Cordova, Alaska, razor clam frequency of occurrence by tide level data ...... 113 Fig. 28. Frequency of tide level exposure, mean sand grain diameter, and abundance of razor clams by tide level at Point Steele Beach, Hinchinbrook Island, Alaska ...... 124 Fig. 29. The relationship among razor clam weight, seawaler lemperalure, auJ lime with growth ill continuum for partial application to fecundity estimates ...... 134 Fig. 30. Sequential inspections chart for testing suspect lots of razor clam shellstock...... 193 Fig. 31. Average sample number curve for testing suspect lots of razor clam shellstock ...... 194

ix LIST OF PLATES

Plate 1. Aerial view of the southwest portion of Orca Inlet, Cordova, Alaska, looking easterly. Little Mummy Island lays at left center; Big Mummy Island, center; and Filipino Island at right center. Heney Range of the mainland lays in the background ...... 38 Plate 2. Aerial view of the southwest portion of Orca Inlet, Cordova, Alaska, looking southerly with Point Bentinck, Hinchinbrook Island at upper right ...... 39 Plate 3. Aerial view of the study site at Rockslide Bar, Orca Inlet with the +4 to + 1 foot ( +1.22 to +0.30 m) tide level study plots exposed ...... 40 Plate 4. Aerial view of the study site at Little Mummy Island Bar, Orca Inlet, showing the +3 to the -3 foot (+0.91 to -0.91 m) tide level study plots ...... 41 Plate 5. Square sampling frame delineating an area of 5 sq. ft. (0.46 m2). The number 2 long-handled shovel shown within the frame has a blade 1 foot (0.3048 m) in length for conveniently excavating to that depth ...... 89 Plate 6. Sampling screen mounted on a wheelbarrow-type frame for washing substrate through to obtain young clams. The screen is lifted out for removal of debris ...... 90 Plate 7. Small, portable Homelite pump mounted in skiff for ease in washing substrate through the sampling screen ...... 91 Plate 8. Complete view of the screening operation at Rockslide Bar, Orca Inlet, with a portion of the southwest shore of Hawkins Island in the background 92 Plate 9. Razor clams collected by screening method showing approximate range of capturable size . . . . 93 Plate 10. Variations in size of 1-year-old razor clams collected by the screening method. Numerals of the lower scale are in centimeters ...... 94 Plate 11. Surf at Point Steele Beach study site, located on the east coast of Hinchinbrook Island. Compare with Plate 1 ...... 98 Plate 12. Study plot at Point Steele Beach site measured 5 by 50 feet (1.52 by 15.24 m) with the long axis parallel to the water line, i.e., tide level...... 99 Plate 13. Study plot at the Point Steele Beach site becoming exposed on the ebb ...... 100 Plate 14. Tote-Gate's were used to transport equipment from Boswell Bay to the Point Steele Beach study site. Screening apparatus is lashed to this machine. Rip channel is in the immediate background with breakers in the distance ...... 1 0 1

X Plate 15. One- and two-year-old razor clams recovered by screening at the Point Steele Beach study site. As shown, the fine, 16 mesh per inch (2.54 em) copper screen is backed by 1 /2-inch (1. 27 em) mesh galvanized screen ...... 1 02 Plate 16. Distances between tide levels at the Point Steele Beach study sites were great compared to the Orca Inlet sites. Tote-Gote's portray the distance between mean lower low water (foreground) and the +1 foot (+0.30 m) tide level 103 Plate 17. Aerial view of Katalla Beach, Cordova Sector 4, looking northwest ...... 104 Plate 18. Aerial view of Softuk Beach, Cordova Sector 4, with the Copper River Delta in the background 105 Plate 19. Numbered stakes at the + 3 foot ( +0. 91 m) tide level, Little Mummy Island Bar, used to locate marked razor clams for the density indicator study ...... 145 Plate 20. The complete set of 50 numbered stakes for the Little Mummy Island density indicator study. The City of Cordova is barely visible at the upper right. The view is looking northeast up Orca Inlet ...... 146 Plate 21. The Point Steele Beach density indicator study site with 50 numbered stakes was subsequently obliterated by tidal currents ...... 157 Plate 22. Current ripples at the Point Steele Beach study site were evidenced following storms . . . . 158 Plate 23. Polly Creek Beach, west side of Cook Inlet, looking northeasterly with Redoubt Point in the background ...... 183 Plate 24. Swikshak Beach, northwest side of Shelikof Strait, Alaska Peninsula, looking northeast . 184 Plate 25. Top view of the razor clam dredge aboard the M/V Montague ...... 186 Plate 26. Razor clam dredge being swung over the side of the M/V Montague off Strawberry Point, Hinchinbrook Island ...... 187

xi ACKNOWLEDGEMENTS

The author wishes to express his gratitude to the following individuals who have aided him in various ways through the course of this study. Mr. Percy Conrad of Glacier Packing Company, Cordova, provided much needed help during the first year of the project. Mr. Ralph Pirtle, Area Management Biologist, Alaska Department of Fish and Game (ADF&G), Cordova, provided temporary personnel and equipment which greatly facilitated some of the field work. Capt. Harry Curran, M/V Montague, ADF&G, Cordova, assisted with dredge and bottom grab studies. Mr. Mel Seibel, Senior Biometrician, Research Section, ADF&G, Juneau, supplied the bases for Table 58 and Appendix 4 as well as offering valuable suggestions. Dr. Kenneth James, Biometrician, Research Section, ADF&G, Juneau, performed the initial computer runs of the density indicator data. Mr. Ivan Frohne, Computer Applications Analyst, Computer Center, University of Alaska, College, Alaska, is commended for the many hours he spent in deriving the multiple regression of density indicators, for providing the bases for variance calculations and the propagation of error formula in Appendix 10, for contributing heavily to the section on stratified random sampling, for determining the order of importance of annuli for use in discriminatory and sequential analyses for deriving the Point Steele Beach gamma distribution curve, and for reviewing and editing the more technical parts of the manuscript. Mr. Lou Gwartney, Assistant Area Management Biologist, ADF&G, Kodiak, provided growth data for the Swikshak Beach and Halibut Bay growing areas, which were used in the discussion of discriminatory and sequential analysis. Mr. Rae Baxter, Fishery Biologist, ADF&G, Bethel, provided information on razor clam growing areas in Southeastern Alaska and the Northwest Gulf of Alaska as well as growth data for those areas. Mr. David Nelson, Sport Fish Biologist, ADF&G, Soldotna, provided information on razor clam growing areas in Cook Inlet. Mr. Jack Lechner, Regional Supervisor and Mr. Dexter Lall, Regional Research Supervisor, ADF&G, Kodiak, and Mr. Glenn Davenport, Area Management Biologist, ADF&G, Sand Point, provided razor clam growing area information for the Kodiak and Al aska Peninsula areas. Mr. Mike Jackson, Fishery Technician, ADF&G, Cordova, plotted the chart of the Cordova Sector 1 survey. Mr. Timothy Brown, Fishery Technician, ADF&G, Cordova, provided an enormous amount of help in obtaining length-weight and gonad pH data as well as obtaining routine samples from Cordova Sectors I and 4 for P.S.P. bioassays. Dr. Neil Bourne and Dr. Daniel Quayle, Fisheries Research Board of Canada, Nanaimo, B. C., critically reviewed the entire manuscript from a biological standpoint. Mr. Joseph Greenough, Biometrician, U. S. Fish and Wildlife Service, Auke Bay, critically reviewed the manuscript with emphasis on population estimation methods. Dr. Donald E. McKnight, Research Chief, Division of Game, ADF&G, Juneau, has generously contributed his time by serving as Scientific Editor of the manuscript. His expertise in this capacity has greatly improved the content of the manuscript and is very much appreciated. Mr. Robert S. Roys, Director, Division of Fisheries Rehabilitation, Enhancement, and Development, ADF&G, Juneau, has been very helpful in providing the means and direction for seeing the manuscript through to publication. Mrs. Alice Wolcott, Administrative Assistant, F.R.E.D. Divison, ADF&G, Juneau, organized the publication sequence. Mrs. Janice Shaw, Clerk Typist, ADF&G, Cordova, spent many hours typing and retyping the preliminary drafts of the manuscript. Mrs. Jeanette Bailey, Clerk Typist, ADF&G, Cordova, assisted in the preparation of figures. Mrs. Karen Wiley checked the spelling of geographical locations, checked references to tables, appendices, figures and plates in the text, and checked to see that all literature cited was indeed cited. Special thanks are extended to my wife Doris, and daughters Amy and Erinn who, ungmdgingly, must have felt that they played second fiddle to Siliqua. It didn't go unnoticed.

xii In Memory of

John David Sol!

1934 - 1974

Biologist - Naturalist

Colleague

and

Friend

xiii INTRODUCTION

History of Commercial Harvests in Alaska The razor clam industry on the west coast of North America was pioneered by P. F. Halferty at Skipanon, Oregon, in 1894 (Pac. Fish. Yrbk., 1916). He was subsequently dubbed "the father of the clam industry of the Pacific Coast." His first pack was cooked on the kitchen stove and sealed in two dozen 1-pin t glass jars. The following day he took the clams to Astoria where the entire pack was sold. Empty receptacles were begged back from each jar sold. After 18 months of hard work he settled on the cooking and canning process that led to the expansion of the industry. He then turned over the razor clam business to his sons G. P. and D. J. Halferty.

By 1914, the canned clam industry on the Pacific Coast had expanded noticeably and unexploited growing areas were being sought, reconnoitered and utilized. This led to the acquisition, in December 1915, of a warehouse on the city dock at Cordova, Alaska, by the Lighthouse Canning and Packing Company of Warrenton, Oregon. The necessary canning machinery was installed and this new plant was ready for operation by January 1916 (Thompson and Weymough, 193 5). The Lighthouse plant at Cordova was undoubtedly the first to pack razor clams in Alaska (earlier records mention a W. H. Royden Packing Plant at Petersburg, Alaska, which in 1914 prepared a 45-case pack of "clams"; most likely these were little-neck or butter clams).

By September 1916, the Pioneer Packing Company under G. P. Halferty had completed construction of a two-line cannery at Cordova and went into operation. These two Cordova plants prepared a total pack of 11,176 standard cases of forty-eight 10-ounce cans, thus heraiding the commencement of the Alaska razor clam industry (Thompson and Weymouth, 1935). In 1919, the Surf Packing Company began operations at Snug Harbor on the west side of Cook Inlet (Pac. Fish. Yrbk., 1920), followed in 1923 by the Hemrick Packing Company at Kukak Bay, Alaska Peninsula, and the Alitak Packing Company at Alitak Bay on Kodiak Island (Pac. Fish. Yrbk., 1925); more were to follow these. Beds in the Cordova area were apparently heavily exploited from the inception of the commercial razor clam fishery. Those in the Cook Inlet and Alaska Peninsula areas were not so ) zealously utilized, however. This expanding industry rode with the ups and downs of Alaska's razor clam populations. The often-quoted work of Weymouth, McMillin and Holmes was written during this early period. Also expanding during this interim was experimental work on refrigeration; fish was the first food to be quick frozen in small consumer-size packages. By 1927, the ) packaged-fish trade had developed remarkably. Not by coincidence, the National Shellfish Sanitation Program had been organized and developed fo r consumer protection from fresh and fresh-frozen shellfish destined to be shipped in interstate commerce. From a meager beginning in 1894 razor clams had, in 30 years, become enmeshed in the entanglement of international trade.

) The following highlights of the razor clam harvest history in Alaska through a 56-year period from its inception to recent times provide an insight into this once-thriving industry. Source of historical information was Pacific Fisherman Yearbook, 191 5-1 966, except as noted in the text.

1916 - The inception of the commercial razor clam fishery in Alaska. ) 1921 - Adverse market conditions resulted in a negligible pack.

) 1924 - The pack slightly surpassed that of 1923 even though the older beds showed signs of depletion.

Investigation of Alaska's razor clam resources was continued by the Bureau of Fisheries, which employed H. C. McMillin to assist Professor F. W. Weymouth in this work, and a thorough survey was made of the principal districts.

As a result of these investigations, the minimum length of clams to be taken commercially in Alaska was set at 4 1/2 inches with a maximum allowance of 3 percent under this size.

The area covered by clam diggers in the Cordova district was gradually extended, helping somewhat to offset the depletion of older grounds. Development of other Alaska clam beaches was just beginning.

1927 - The Alaska razor clam pack was disappointing; the total output was about 10,000 cases under that of the previous year. Unfavorable weather conditions and scarcity of clams on the beaches were, as in 1926, responsible for the decreased pack.

1929 - Razor clam harvest conditions and resulting pack were much better than the preceding year. The matter of a duty on canned clams that entered the United States from foreign countries occupied the attention of the Pacific Coast clam packers during much of the year. Japanese clams reportedly retailed at figures actually below the price quoted by the American packers to the jobbers.

1930 - Alaska razor clam canning operations were the largest since 1926.

The Hawley tariff bill was enacted in the spring which removed canned clams from the free list and subjected them to an import duty of 35 percent. This protection was sought by American clam packers, who had begun to feel the competition of Oriental canned clams.

1931 - The Alaska razor clam production continued to gain steadily.

Early in the year, Maine and Massachusetts hardshell clams were placed on the San Francisco market on consignment in quantity and offered ex-warehouse at extremely low prices. Also, importations of Japanese canned clams continued to some extent in spite of the duty.

193 2 - Alaska razor clam production increased from the year before. However, the digging was so heavy in the Cordova district that the season was closed June 25 instead of July 15. Despite the early closure, the razor clam market remained comparatively firm.

1933 - Razor clam production was curtailed in all districts. The drain on the Alaska beds was so heavy in 1932 that regulations covering the year 1933 imposed packing quotas in some districts.

1934 - In May changes in the tariff on canned clams were proclaimed by the President of the United States. These changes resulted in the levy of a 35 percent duty on the American selling prices of the imported clams, rather than upon their declared value in the country of origin as had been the case previously.

2 193 5 - For the first time, fishery regulations placed a quota on the production of western Alaska beaches. The district lying along the mainland coast on the west side of Cook Inlet was limited to the equivalent of 12,500 cases of forty-eight 1 /2-pound cans per case. The Cordova quota of 23,000 cases for the spring season was attained, but the fall season limit of 7,000 cases was not filled.

Late in the year the Bureau of Fisheries published the report of a scientific investigation by Thompson and Weymouth of the condition of the razor clam fishery in the vicinity of Cordova. These authors concluded that the fishery showed no signs of depletion, nor of substantial increase, and that it evidently was able to indefinitely support the fishery permitted under then existing regulations.

1936 - The condition of the razor clam beaches in Alaska appeared to be excellent.

1940 - Alaska razor clam production was the highest of any year for the past nine with the exception of 1938.

1942 - A number of cases of an undisclosed illness occurred which were ascribed to the consumption of improperly cleaned shellfish . Th ese illnesses resulted in a temporary closure of clam digging until responsibility for the trouble could be fixed. Commercially canned razor clams were shortly cleared of any possible blame; however, the closure occurred during the heart of the season.

1945 - Evidently the razor clam fishery in the Cordova area was in healthy condition, fo r the quota was readily taken in a relatively brief season.

1946 - Hardshell clam canning activities were checked to some extent by very severe inspection rules of federal authorities.

194 7 - Federal fo od specifications caused fu rther restrictions of hardshell clam canning and made successful packing difficult. There was a growing tendency to freeze razor clams. Because many clams were frozen in the shell for crab bait, it was difficult to segregate the portion of the freezing which was for human consumption and the part which was destined for bait.

In coastal areas adjacent to beach resorts the demand for frozen razor clams increased substantially. Popularity of the clams in this form was widely demonstrated.

1948 - Alaska Fishery Regulations provided for a uniform closed season for razor clams in the entire Cook Inlet area effective July 10 to August 31.

Hardshell clam canning on the Pacific Coast continued to suffer under restrictive limitations imposed by fe deral regulation. As a result of these rigid specifications there was a complete su spension of this enterprise in Alaska, and activity in Washington was sharply limited.

1949 - Hardshell clam canning in Alaska remained little more than nominal as industry and government researchers sought to overcome technical problems (presumably paralytic shellfish poisoning) which exercised restrictive influences on this business for a number of years.

1950 - Hardshell clam canning on the Pacific Coast remained in a depressed state due to two fa ctors: (1) competition of Atlantic canned clams; and (2) rulings of the Food and Drug Administration that eliminated the industry in Alaska.

3 The fall quota of 2,000 cases for the Cordova district was shifted to the spring quota of 40,000 cases fo r a total spring quota of 42,000 cases.

1952 - Pacific hardshell and razor clam canners faced very severe competition. Imports of Oriental clams were damaging to the business of Pacific packers of hardshell clams, and Atlantic Coast canners of sea clams made substantial inroads on markets formerly supplied by razor clam producers.

1953 - Pacific clam canneries again faced very heavy competition from Atlantic Coast goods and foreign imports.

1954 - Razor clam canning was lower than previous averages despite greater abundance on the Washington coast. The import situation discouraged small operators and production of razor clams was realized largely by Halferty interests.

The tendency of smaller American operators to withdraw from clam canning, particularly in razor clams, reflected the seriousness of their competitive problem. Atlantic Coast minced clams at lower prices than razor clams moved into the Pacific market to a degree which was discouraging to the smaller packers.

1956 - Pacific clam packing became more restricted to razor clams due to the pressure of competition from abundant supplies of hardshell clams from Japan and the Atlantic Coast of the United States, from Maine to New Jersey.

Atlantic sea clams, dredged mechanically from offshore bottoms, were produced at much lower cost than Pacific varieties, which had to be dug by hand. In addition to low-cost production, the large Atlantic sea clams yielded an excellent product which was said to approach in quality and often substitute for what was considered the superlative razor clam.

1959 - Pacific razor clam canning exceeded that of 1958 by 50 percent, due mostly to the resumption of operations in the Cordova area, where diggers' demands the previous year virtually suspended operations.

1960 - Most of the Pacific hardshell and some of the razor clam canning enterprises were rendered economically unfeasible due to strong competition from Atlantic Coast clams.

The result was a tendency toward marketing Pacific hardshell clams - and razor clams to some extent - fresh and in the shell, a trade that seemed to hold promise due to the steady population growth in the Pacific states.

Efforts to extend the Pacific Coast clam fishery, after the manner of the notable development on the Atlantic Coast, did not produce conclusive results. Consequently, utilization of the hardshell clam resources of Washington, Oregon, British Columbia and Alaska for canning declined. Competition by Oriental and Atlantic clam products continued to grow.

1961 - Razor clam production on the Pacific Coast remained close to the average of the previous decade, but only through the ability of the Kodiak Island area to produce more heavily than usual. Increased production from the Kodiak area thus made up for marked falling-off in production of the Cordova area, previously the mainstay of razor clam production.

4 1962 - Competition in the canned clam business continued to increase and developments promised fu rther acceleration of that strong trend.

Production of Atlantic Coast sea clams increased in volume and continued to capture a large share of the Pacific Coast market and the inland sales territory formerly supplied by Pacific canners.

Efforts to emulate the successful application of mechanical harvesting of clams to Pacific varieties proved discouraging.

Negotiation of a fresh and frozen shellfish certification agreement between Japan and the United States late in 1962 portended an eventual increase in imports of frozen clams from Japan.

1963 - There were fu rther tendencies toward introduction to the Pacific Coast of mechanized methods of harvesting, such as those employed in the clam industry of the Atlantic states.

Alaska and Oregon adopted regulations which permitted the use of hydraulic, suction or mechanical methods in clam harvesting.

One of the notable aspects of Alaska clam operations was the continued concentration of the business in the Kodiak district as a result of the apparent decline in abundance, or economic availability, of clams in the long-dominant Cordova area.

1964 - The Good Friday earthquake, March 27.

1965 - Oam canning on the Pacific Coast reached a new low and the United States razor clam canning industry virtually suspended operations. Supplies of razor clams apparently came almost entirely from continuing operations at Masset, British Columbia, at the northerly end of the Queen Charlotte Islands.

The Alaska earthquake had dealt the Alaska razor clam industry a crushing blow.

Decline of the Pacific clam canning industry almost to the point of disappearance could be traced to the cumulative effect of several factors:

(1) Utilization of virtually the entire sustainable yield by recreational diggers.

(2) Skyrocketing production costs due to the necessity of digging the clams by hand.

(3) Mechanized competition evidenced by productive mechanical dredging on the Atlantic Coast.

( 4) Acceptable and cheaper substitutes in the form of Atlantic sea clams.

(5) Fresh market demand for razor and hardshell clams resulting from increased population and improved transportation.

More specifically the impact of these factors in Alaska were as follows:

(1) The eastside beaches of Cook Inlet were closed to the commercial harvest

5 of razor clams in 1960 in order to reserve them solely for recreational digging (Jim Rearden, former Area Management Biologist, ADF&G, pers. comm.).

(2) As of 1972, the cost of large-scale production in the Cordova area, where hand digging was still mandatory, would have resulted in a very expensive gourmet pack. Bait clam demand and labor costs would boost the price of the product to nearly prohibitive levels according to an Alaska Packers Association official (A.P.A. took over Halferty interests in 1959).

(3) In an attempt to meet mechanized competition, the Alaska Packers Association constmcted and tested a hydraulic clam harvester at Swikshak Beach in 1963. This harvester was based on the type that is used in the soft-shell clam industry in Chesapeake Bay. Results of these tests as reported by Ralph S. Jones, A.P.A. official, on September 27, 1963, were as follows:

(a) The hydraulic clam harvester, as modified during field trials, will catch razor clams in commercial quantities on an economical basis.

(b) Use of the harvester was less injurious to the clams than hand digging.

(c) Properly rigged and adjusted it will, with rare exception, capture all the clams in its path.

(d) Its use will open up new areas to harvest not now practicable with hand digging methods, including areas beyond those uncovered by low tide.

(e) Upon being put in regular service it is anticipated that minor improvements would fu rther increase its productivity.

(f) The harvester was thought to be especially adaptable to the Cordova area where the majority of the beds are protected by a chain of islands and lie under relatively calm, shallow waters.

(g) It was suggested that Alaska Department of Fish and Game regulations be modified to include use of mechanical means of harvesting clams on the beach as well as afloat. This was to be accomplished at the November 1963 meeting of the Board of Fish and Game.

(h) Further production experiments with the harvester mounted on fishing vessels and a land-type machine were desirable.

It is necessary, here, to point out that relative to item (b), neither the experience nor the skill of the hand diggers are known nor was there any indication whether they were digging clams for human consumption (with care not to incur breakage) or for bait (rapid, careless digging). Regarding item (g), no studies had previously been conducted in Alaska to determine what detrimental effects, if any, are associated with mechanical harvesting. That is, what is the impact of removal, stmctural damage and current drift of small clams, and alteration of the natural ecology of the habitat?

During 1971, the British Columbia Department of Fisheries constmcted, in cooperation

6 with B. C. Packers Limited, a hydraulic razor clam dredge for use at Masset beach. According to Mr. I. H. Devlin, Project Engineer (pers. comm.), the problem in British Columbia was to provide a stable working platform from which to operate a clam dredge in the surf. The ultimate choice was a rubber-tired vehicle which could operate in a minimum of 3 feet of water and would be capable of operating in 6 feet of water with a 6-foot swell. Two centrifical pumps were mounted on the working deck providing 1,600 U. S. gpm at 230 TDH (total discharge head). Piping arrangements allowed the water flow to be distributed in any variation between the cutting head and the conveyor bucket. Oams were conveyed from the dredge bucket up a flight conveyor to the working deck where those of marketable size were hand-picked off the conveyor into baskets. Immature clams and debris were conveyed off the rear of the machine and fell down a chute into the trench dug by the dredge bucket.

This machine was powered by two 65-hp turbo-charged Ford diesel engines, each engine driving the front and back wheels on one side, thus providing four drivewheels. Steering was accomplished by altering the speed of the engines.

Subsequently, Mr. Devlin reported (pers. comm.) that during trial periods in November and December 1971, the digger harvested 7,100 pounds of clams averaging 700 pounds per hour. At times it harvested at a maximum rate of 1,000 pounds per hour. Subsequent to these trials, the machine was removed from the beach to undergo modifications to its digger head in attempts to reduce the amount of damage that was done to sublegal size clams.

(4) To compare prices of canned razor clams and cheaper substitutes, shelf prices of a variety of canned clams both from the Atlantic and Gulf coasts, from Washington, and from Japan were adjusted to compensate for differential can size. This comparison indicated that the shelf price in Cordova, Alaska, of razor clams canned in Cordova was 62 percent higher than that of Maine clams (Spisula solidissima); 340 percent higher than Maryland clams (Mya arenaria); 116 percent higher than Washington clams (presumably Pro to thaca); 106 percent higher than Japanese clams (presumably Pro to thaca); and 9 percent higher than Mississippi oysters (Ostrea).

(5) Fresh market demand of razor clams has been increasing steadily since the three major growing areas in Alaska were approved for commercial harvest in 1970.

Figure 1 shows the major historic razor clam growing areas in Alaska. Data in Table 1 provide an in-depth account of the commercial harvest history for the Cordova area and Fig. 2 depicts harvest trends during this period. Recent commercial harvest data from the Cordova area are shown in Appendix 1. Table 2 serves to illustrate the comparative production history between the Cook Inlet and westward growing areas.

History of Toxicity Problems in Alaska The National Shellfish Sanitation Program is a cooperative effort by an association of state and federal agencies to preserve and manage oyster, clam and mussel resources for beneficial uses. Development of the current national program can be traced back to early American colonial times. Greeting these first settlers was a land of almost unimagined natural wealth. Although boundless forests, rich agricultural soils, vast mineral deposits

7 8 Table 1. Commercial razor clam hmvest history for the Cordova, Alaska, area 1916 to 1973.

Pounds Per Pounds Per Total Tide Digger Total Total Man Average Seasonal Number Mean Pounds Cases Total Tides Dig Per Average of Age of Year Dug (48-1/2#) Diggers Dug Digger Dig Canneries Oams

1916 429,846* 13,970 35 11,533 2

1917 3,590,115* 116,679 133 25,350 2

1918 1,987,731* 64,601 87 21,456 3

1919 1 ,051 ,923* 34,188 142 6,957 2

1920 249,385* 8,105 57 4,109

1921** 0 0 0 0 0

\0 1922 685,1 92* 22,269 24 26,811 6

1923 1,456,000* 47,320 121 11,300 6 6.44

1924 1 ,858,538* 60,403 316 5,523 8

1925 1 ,573,385* 51,135 347 4,258 7

1926 472,000* 15,340 229 1,936 6

1927 356,154* 11,575 106 1,189 172.031} 1,930 4

1928 466,962* 15,176 96 2,630 210.911/ 5,778 2 1929 666,731 * 21,669 108 3,650 193.30 6,535 3 6.97 1930 713,423 * 23,186 172 3,984 162.86±.1 3,772 4 6.98 1931 1,357,114 32,851 226 5,560 183.oo2/ 4,502 3 6.60 Table 1 (continued). Commercial razor clam harvest history for the Cordova, Alaska, area 1916 to 1973.

Pounds Per Pounds Per Total Tide Digger Total Total Man Average Seasonal Number Mean Pounds Cases Total Tides Dig Per Average of Age of Year Dug (48-1/2#) Diggers Dug Digger Dig Canneries Oams

1932 1,833,3 58 49,4 14 324 13,218 133.616/ 5,451 5 6.26

1933 845,746 24,324 410 5,179 135.93 7/ 1,717 5 6.22 1934 1,233,836 31,509 246 3,905 216.4� 3,43 5 6 7.32 1935 826,421 21,529

1936 957,549 21,788

1937 1,423,933 28,697 223 5,462 0 1938 1,315,631 31,920 269 4,344 8.30

1939 1,540,607 31,264 253 4,980 8.40

1940 1,449,299 41,242 305 6,700 216.30 4,752 9 8.87

1941 906,461 19,881 145 5,697 8.90

1942 1,327,390 46,703 202 7,3 15 9.20

1943 1,671,602 48,730 184 6879/ 9,501

1944 1,647,733 45,587 162 689.!.Q/ 10,467

1945 1,657,722 45,190 188 647.!.!/ 8,288

1946 1 ,746,205*** 48,145 182 4,922 35511.1 9,594 10 9.42 Table 1 (continued). Commercial razor clam harvest history for the Cordova, Alaska, area 1916 to 1973.

Pounds Per Pounds Per Total Tide Digger Total Total Man Average Seasonal Number Mean Pounds Cases Total Tides Dig Per Average of Age of Dig Year Dug (48-1/2#) Diggers Dug Digger Canneries- Oams

B.R. 50,242 1,154 (17) 102 493 2,955 (1) 12.01

1947 606,540 15,830 153 2,210 274 3,964 12

1948 1,154,903 30,548 207 3,374 342 5,579 8

1949 1,478,255 36,804 255 5,362 27611) 5,797 10

1950 1,520,416 40,395 345 5,921 257 4,407 15

B.R. 140,079 3,56 1 (30) 393 356 4,669 (1)

1951 1,535,119 40,423 355.!.2/ 5,702 269 4,324 13 8.36

B.R. 124,033 2,773 (61)1..2./ 479 259!±/ 2,033 (2) 8.51

1952 1,265,430 30,946 2351..2./ 4,530 279 5,372 12 8.08

1953 1,485,937 38,364 32o.!2./ 5 , 52ill/ 269 4,644 8 7.37

1954 1,216,758 31,367 1971..2./ 5,3891..2./ 226 6,176 8 7.6 1

1955 1,377,109 44,817 34ol2./ 6,5171..2./ 211 4,046 8 7.27

1956 703,659 21,330 20916/ 3,169.!£/ 222 3,367 5 7.55

1957 1,018,498 27,560 27ill/ 5,8441£/ 174 3,727 5 7.56

1958 32,395 83 1 STRIKE Table 1 (continued). Commercial razor clam harvest history for the Cordova, Alaska, area 1916 to 1973.

Pounds Per Pounds Per Total Tide Digger Total Total Man Average Seasonal Number Mean Pounds Cases Total Tides Dig Per Average of Age of Year Dug (48-1/2#) Diggers Dug Digger Dig Canneries Oams

1959 507,731 13,017 183 3,196 159.!2/ 2,774 6 7.83

1960 433,930 10,367 284 1,528

1961 261,628 6,868 111 1,823 127 2,091

1962 208,698 3,398

1963 86,340 37 937.5* 92* 9.5*

1964 89,275 860* 103* Show Slightly Better than 1963 - N 1965 87,700 1122.5* 86*

1966 28,600 731.§_/ 315* 86*

1967 114,900 106 !§)

1968 72,900 1211.§_/ 3

1969 26,887 9�1 3 17I

1970 27,909 88.!§./ 3 1]_1 1971 37,972 3 1972 30,326 1973 30,818 I/ Five best diggers = 172.21 2! Five best diggers = 235.78 3! Five best diggers = 214.16 4! Five best diggers = 184.62 S/ Five best diggers = 236.39 6! Five best diggers = 187.70 7/ Five best diggers = 174.16 S/ Five best diggers = 248.46 9I Eight best diggers TO/ Eight best diggers TII Eight best diggers TI/ Eight best diggers TI/ Eight best diggers = 438.2 14/ Six best diggers = 390.2 TS! Top 20 diggers = 209 T6! Estimate 17/ Refer to tables and figures in Appendix I

B. R. = Breakdown of information from the Bering River area w * Approximation only ** Adverse market conditions *** Abundance less than 1941-4 2 120 • Cases Packed (48-1 /2#) Pounds Dug 110 J I 1916-1963 1916-1973 X= 30,569 X= 909,287 100 -1 II CJ= 20 473 CJ= 717 240 90 ah = 2:955 CJ/yiN= 94 :178 ,.-_ C/l .::: cr ro = 2,090 v-w= 66,594 () CJ/ 80 fw = N - - 1 I I 70 00 .q- '-' C/l

'- 0 C/l 50 "0 .::: +>- ro C/l ;:::l 0 40 � 30

20

10

V') 0 V') 0 V') 0 V') 0 V') 0 V') - N 01 C") C") .q- "<:!" V') V') \0 \0 0\ 0\ 0\ 0\ 0\ 0\ 0\ 0\ 0\ 0\ 0\ - - - - -

Fig. 2. Trend of razor clam production, Cordova, Alaska, 1916-1963. Table 2. Comparative history of razor clam production in the Cook Inlet and Kodiak Island areas based on the standard case of forty-eight 1/2-pound cans or pounds (#) where indicated..l/

Year Cook Inlet Kodiak Island

1916 1917 1918 1919 3,207 P* 1920 498 P* 1921 3,000 P* 1922 21,268 P* 1923 19,595 p 14,042 K,A 1924 6,532 P* 23,618 K,A 1925 No Pack 28,898 K,A 1926 No Pack 19,716 K 1927 1,052 P* 14,821 K 1928 No Pack 108 K 1929 No Pack 9,311 K 1930 No Pack 13,532 K 1931 Volume Unknown P 11,568 K 1932 3,910 P* 7,230 K,A 1933 11,83 1 P,N,Kust. * 111 A 1934 438 N,R* Small Pack Volume Unknown H 1935 689 N 12,254 K,H 1936 Records Missing 11,3 14 K 1937 347 p No Pack 1938 150 N No Pack 1939 313 N No Record 1940 310 N No Pack 1941 No Pack No Pack 1942 No Pack No Pack 1943 No Pack No Pack 1944 No Pack 6,000# Frozen Sold to Armed Forces S 1945 625 P* or N* 163 cases and 15, 1 00# Frozen S 1946 476 P* or N* 2,973 s 1947 499 P* or N* 3,064 s 1948 90 P* or N* 1,432 K,S 1949 403 P,N 5,328 K 1950 304,073# to Kodiak, 14,244 S,A Seldovia & Homer for process, or trans-shipment p

15 Table 2 (continued). Comparative history of razor clam production in the Cook Inlet and Kodiak Island areas based on the tandard case of forty-eight 1 /2-pound cans or pounds (#) where indicated.lf

Year Cook Inlet Kodiak Island

1951 4,680 p 13,256 s 1952 No Pack No Pack 1953 No Pack No Pack 1954 No Pack No Pack 1955 No Pack 9,526 s 1956 4 KAS.* 12,926 s 1957 82 KAS.* 12,653 s 1958 No Pack 13,505 s 1959 No Pack 13,240 s 1960 372,872# to Kodiak 10,927 s for pro- cessing P 1961 244,585# to Kodiak 17,905 s for pro- cessing P 1962 195,650# to Kodiak 9,309 s for pro- cessing P 1 963 No Pack 7,29 1 s 1964 No Pack No Pack 1965 No Pack 20,000# for bait and Fresh Mkt. S 1966 No Pack 15,429#* bait and Fresh JVJ< t. S,D 1967 No Pack 2,155#* for bait and Fresh Mkt. S 1968 No Pack 6,384#* for bait and Fresh Mkt. S 1969 No Pack 12,029# for bait and Fresh Mkt. S 1970 No Pack 132,261 for bait and Fresh Mkt. S. 1971 15,171# for Fresh 189,700 for bait Mkt. or and Fresh Mkt. S bait P

Prepared from Pacific Fisherman Yearbooks, and annual reports of the U.S. Fish ll and Wildlife Service and the Alaska Department of Fish and Game.

16 Table 2 (continued).

Explanation of letters following case pack entries p = Oams obtained from Polly Creek Beach. P* = Clams presumed to have been obtained from Polly Creek. N = Oams obtained from Ninilchik Beach. N* = Oams presumed to have been obtained from Ninilchik Beach. Kust.* = Oams presumed to have been obtained from the Kustatan area. R* = Oams presumed to have been obtained from Redoubt Bay. Kas.* = Clams presumed to have been obtained from Kasilof Beach. K = Oams obtained from Kukak Bay, Alaska Peninsula. A = Oams obtained from Cape Alitak, Kodiak Island. H = Oam3 obtained from Halibut Day, Kodiak hlauJ. = s Oams obtained from Swikshak Beach and, to a minor extent, Village Beach at Kaguyak, Alaska Peninsula. D = Oams obtained from Duck Bay, Afognak Island.

17 and space were in quantities and varieties previously unknown, one of the most valuable and readily usable of these natural resources was the food of the sea, particularly along the estuaries. That shellfish were foremost among staple food items should come as no surprise.

The great value of the sea's renewable resources to these early settlers was reflected in colonial legislation designed to encourage their wise use. Beginning in 1658, legislation was passed that was designed to regulate harvesting, presumably as conservation measures to guarantee a continuing supply.

From 1900 to 1920 the public health problems associated with shellfish in the United States unveiled a new dimension to natural resource utilization; shellfish could not be used for food unless of acceptable sanitary quality. This concept was clearly recognized in the Public Health Service sponsored conference of 1925 in which the ideas of the present cooperative program were first outlined and its administrative foundation established. Participants at this conference concurred that: (1) shellfish represented a valuable natural food resource; (2) cultivation, harvesting, and marketing of this fo od resource were valuable components in the financial bases of many coastal communities; (3) a joint state and federal program was necessary to permit the safe use of this resource; and ( 4) the transmission of disease by shellfish was preventable and therefore could not be tolerated. As a result of this conference a National Shellfish Sanitation Program (NSSP) was established.

In view of the past history of the shellfish industry in the United States, the goals of the NSSP were: (1) the continued safe use of oysters, clams, and mussels; and (2) active encouragement of water quality programs which would preserve all possible coastal areas for this beneficiai use.

February 1972, J. David Oem, Director of the Division of Shellfish Sanitation, United States Department of Health, Education, and Welfare (pers. comm.) stated that: "In the beginning of the NSSP (1925), the States were requested to develop sanitary control programs for commercial species of shellfish in their respective jurisdictions. The first concern in these early days was with oysters, but in time clams and mussels were considered, as it was learned that these species could be vectors of disease if not produced under similar sanitary controls. In what year the Territory of Alaska joined the program is not clear. When Alaska became a participant in the NSSP all commercial species of oysters, clams, and mussels were allowed to be certified for interstate shipment unless the Territorial Government had restrictions in their codes or regulations."

Dr. Oem continued, stating: "In 1954, the U.S. Public Health Service mutually withdrew Alaska's endorsement because of the Territory's inability to provide a satisfactory control program that would insure shellfish free of paralytic shellfish poison (P.S.P.). In that year, certified interstate shipments of butter clams were sampled and found to contain hazardous levels of P.S.P. Since 1954, Alaska has not been able to develop a sanitary control which will satisfy public health officials."

In 1963, the Alaska Department of Health and Welfare declared all beaches in Alaska suspect of containing poisonous shellfish, and commercial utilization of clams, mussels, and similar shellfish species was strictly forbidden unless the harvest areas were approved and certified by that department. During the following seven years all clam growing areas in Alaska remained technically closed and unapproved for commercial utilization due to insufficient funds, equipment, personnel, and testing facilities essential for the establishment of a proper shellfish sanitation program.

18 Funding became available to the Alaska Department of Fish and Game in January 1969 for implementation of the Razor Oam Investigations Project. Primary objectives of the investigation were: (1) to collect supportive data showing that razor clams from major growing areas in Alaska are safe for human consumption; (2) to actively coordinate sanitary surveys and sampling programs; and (3) to pursue the necessary steps for clearance of razor clam growing areas for commercial harvest for human consumption. Secondary objectives were: (1) to collect vital life history data; .(2) to determine accurate censusing methods for management of the various razor clam populations in Alaska; (3) to update the commercial harvest history in Alaska; and ( 4) to provide an account of general growth characteristics from many growing areas in Alaska.

When I initiated this program in 1969, it became evident that policymakers were unfamiliar with the razor clam harvest history in Alaska, did not understand procedures to follow for growing area clearance, and were not aware of the National Shellfish Sanitation Program. Unfortunately, the following syllogism seemed to dominate considerations of commercial harvests of razor clams : butter clams on Porpoise Island, Alaska, contain high levels of paralytic shellfish toxin ; butter clams are bivalve mulluscs; therefore, all bivalve molluscs in Alaska contain high levels of paralytic shellfish toxin.

Remarkably, variations of this syllogism were still being stated following 54 years of commercial razor clam harvest in Alaska. Granted, butter clams (Saxidomus giganteus), from Porpoise Island in Southeastern Alaska do have a history of high toxicity and were sought by the United States Army for chemical warfare material. Regardless, to label an entire order of molluscans along a 6,640-mile coastline as "suspected toxic," as was done in 1963 without furnishing proof one way or the other (at least in the three historic razor clam harvest areas) was, in my opinion, not a wise course of action.

Progress towards reestablishing a viable razor clam industry in Alaska was slow, but in August 1969 Mr. John Kuhn, Alaska Department of Health and Welfare, conducted a sanitary survey of the Cordova razor clam growing area. Mr. Kuhn recommended that the area be cleared for commercial harvest " of razor clams for subsequent canning by heat-process vacuum-pack methods."

The flrst year of the project (1969) ended with a record of bioassays regarding P.S.P levels in Alaska razor clams conducted at the Northwestern Water Hygiene Laboratory, Gig Harbor, Washington, and a record of seawater coliform density analyses performed at the Alaska Department of Health and Welfare laboratory in Anchorage, Alaska. I collected all clam and most water samples in the Cordova area and coordinated these activities in the Cook Inlet and Alaska Peninsula area.

In regard to the bioassays for P.S.P. levels, the National Shellfish Sanitation Program Manual of Operations, Part I stipulates: "If the paralytic shellfish poison content reaches 80 micrograms per 100 grams of the edible portions of raw shellfish meat, the area shall be closed to the taking of the species of shellfish in which the poison has been found." Note that the words "edible portions " are used. Razor clams are prepared commercially fo r human consumption by eviscerating the clams and removing the dark portion of the siphon.

Paralytic shellfish poisoning should not be taken lightly, as high enough quantities will cause death by respiratory paralysis. According to the National Shellfish Sanitation Manual of Operations, Part I: "The minimum quantity of poison which will cause intoxication in a susceptible person is unknown. Epidemiological investigations of paralytic shellfish poisoning in Canada have indicated 200 to 600 micrograms of poison will produce

19 symptoms in susceptible persons and a death has been attributed to the ingestion of a probable 480 micrograms of poison. It has also been shown that the heat treatment afforded in ordinary canning reduces the poison content of raw shellfish considerably."

In regard to the seawater coliform density analyses, the National Shellfish Sanitation Program's definition of an Approved growing area is that in which "the coliform median MPN (most probable number) of the water does not exceed 70 per 100 ml., and not more than 10 percent of the samples ordinarily exceed an MPN of 230 per 100 ml. for a 5-tube decimal dilution test (or 330 per 100 ml., where the 3-tube decimal dilution test is used) in those portions of the area most probably exposed to fecal contamination during the most unfavorable hydrographic and pollution conditions." The National Shellfish Sanitation Program's definition, in part, of a Conditionally Approved growing area is that in which "the sanitary quality ...may be affected by seasonal population, or sporadic use of a dock or harbor facility." Prohibited areas, as defined in part by the National Shellfish Sanitation Program, are those " ...contaminated with radionuclides or industrial wastes ...and the median coliform MPN of the water exceeds 700 per 100 ml. or more than 10 percent of the samples have a coliform MPN in excess of 2,300 per 100 ml."

During 1969, razor clams were collected from Cordova (February 8 to September 26), Cook Inlet (May 30 to August 29), and Swikshak (June 30) growing areas. Each sample of clams was prepared as two subsamples; i.e., eviscerated with the dark portion of the siphon removed, and uneviscerated.

Of the 152 razor clam samples submitted from Cordova Sectors 1, 2, and 4 (Figs. 3 and 4 ), two uneviscerated samples showed detectable levels of paralytic shellfish toxins. Levels of toxicity were 55 micrograms per 100 grams of meat (henceforth referred to as ug/l OOg) at Strawberry Reef and 35 ug/lOOg at Softuk Beach. Both samples were collected on July 12, 1969. Interestingly enough, the eviscerated counterparts to these samples showed no detectable toxins, i.e.,<3 1 ug/1 OOg. Cordova Sector 3 was not sampled due to low abundance of clams.

Four mussel samples were collected on August 17 and 18, 1969, from four widely separated points in the Cordova area. Bioassay results revealed no detectable toxins, i.e., <29 ug/1 OOg.

Seawater analysis to determine coliform density was performed on 39 samples collected from July 28 to August 25, 1969. The majority of the samples (21) reflected "coliforms absent," and most remaining samples (8) had MPN's of 2.2. Notable exceptions to these results were found in Cordova Sector 4 from Strawberry Reef (MPN = 9.1 ), Katana Beach (MPN's of 5.1, 23, and 16), and Kanak Island (MPN's of 2.2, 141, and 70). The high MPN's in this sector were attributed to the salmon fishing fleet that was engaged in operations in the area during the sampling period. For some reason, coliforms were absent from samples obtained from Softuk Beach, which lies midway between Strawberry Reef and Katalla Beach.

Twenty-four razor clam samples were submitted from three growing areas in Cook Inlet: Oam Gulch and Happy Valley on the east side and Polly Creek on the west side (Figs. 5 and 6). None of these samples showed detectable levels of P.S.P. In addition, one mussel sample collected from Chisik Island during late August similarly displayed no sign of P.S.P.

Seawater samples from the Polly Creek area showed MPN's no higher than 16, while samples

20 u u u u u

miles Scale : 1 inch 2. 75

Cor dova

· ·.,· . N . ·Z . : ,_. . .. - . 1s . (· (/ '···· · 1 -�.'P-. .• ,_ ,·-..·. · 7 · 5/ ; . ., . . 4--�-:�;__::· · · � .. . 2J · .�2_:/ -.·. ·-- -- -, I · . �� : : I . · · - · · . ' . / : . : . . 1: • • 1: :: 7 .:. . . . 6 .:t•; .. ; ! . . , / . . . · • :8: . >:� ,._ . � .. r _ >• · n : . ....··. : : . ·_) .... : -· ,• B ' .: · ...... '·e'(flO O �ea ar · ·.:·. . : /.·:. . j � }:J· :j' .'i . · I �-· ·a •. ·· ·l • · H H : - i':gg ls -- n H J. Cll Hinchinb rook Island1 �: al'lds · I : H .. ·:: · .>:: ·· · . 2 · . . I · 1 �-. :·,· ·�.; ��-- =.�· · "0 :: I I t::: I Cll - - -- I - - ·. ···21 r-1 ·--� ·� � (/) H I · Steele bO I bO I Sector tl2 rLl I _I_ _ .J L------__ 2 Fig. 3. Cordova Sectors 1 and with razor clam sampling stations designated. (Legend on fo llowing page) · ·

·

· Legend for Figure 3

1. Northeast Concrete Bar

2. Hartney Bay

3. Big Point Bar

4. Shag Rock Bar

5. Big Mummy Island Bar

6. Twin Rocks Bar

7. Graveyard Bar

8. Inside Ocean Bar

9. Channel Junction Spit

10. Southwest Ocean Bar

11. Point Steele Beach

12. Southwest Twin Rocks Bar

13. Erickson Bar

14. Bar between Big and Little Mummy Islands

15. Little Mummy Island Bar

16. Canoe Pass Trail Bar

17. Rockslide Bar

18. Shirttail Bar # 1

19. Shirttail Bar #2

20. Shirttail Bar #3

21. Outside Egg Islands Beach

22. Copper Sands

NOTE: The above list of locations is local names and will not be found in the Dictionary of Alaska Place Names.

22 . . ··

· ·· ·

· · r ··· · · ·· · · ... Strawberry Reef

· ; ... Martin Islands�

: ' . . - ...... '· .· ...... : ,' . · . ··� .: ·: .·.. : . . ·. :. . ·.

" ' 'o I ·: · . . · �\r :.'

\� Ma rtin Islands Katalla Beach

Scale : 1 inch 1. 35 miles

Fig. 4. Cordova Sector 4 vvith razor clam sa mpling stations designated.

23 .:::'· ·

Cape Kasilof , . ...

.. � : ·

.. , .

r ·'

·'

...

Clam Gulch

Happy Valley

Razor clam sampling stations lo cated at the east side of Co ok Inlet Fig. 5. . 24 Polly Creek (7

�Polly Creek Beach

)

Ch isik Island

)

)

Razor clam sampling stations located at Polly Creek Beach, west side of Co ok In let. Fig. 6. 25 ) collected from Oam Gulch and Happy Valley had MPN's ranging from 16 to 348.

I also felt that the seawater should be analyzed to ascertain levels of pesticides and herbicides. Because Cook Inlet receives wastes and drainoff from the most populated regions of Alaska, namely Anchorage and the Matanuska Valley, and because the use of D.D.T. in Alaska is discouraged by the Alaska Department of Fish and Game, the Alaska Department of Health and Social Services and the military, I contacted Dr. Curtis H. Dearborn, Associate Professor of Horticulture at the University of Alaska and the Agricultural Experiment Station at Palmer. Dr. Dearborn provided a complete list of pesticides and herbicides that were used in the Matanuska Valley. Most of these chemicals were nonresidual. Some were considered mildly residual, but due to their limited use, were not considered significant. Chlordane was the only highly residual pesticide mentioned, but because Diazanon is more effective for root maggot control, Chlordane was seldom used. Dr. Dearborn stated that the agricultural community "does not use these chemicals in rates that would be toxic to anything they were not intended for" ... and that... "if any residuals got into Cook Inlet, they are so insoluble that they would be in immeasurable quantities."

To test Dr. Dearborn's contention I coordinated the collection of four gallons of seawater from four razor clam growing areas in lower Cook Inlet to determine if there was any trace of Chlordane. One gallon each was obtained at Oam Gulch, Gravel Pit Access #2, and Happy Valley on October 6 and from Polly Creek Beach on October 7, 1969. These samples were sent to the Federal Water Pollution Control Administration, Portland Laboratory, Portland, Oregon, for analysis. Results of the analyses evidenced a value of less than 1 nanogram per liter for each of the samples. Although the number of samples was small, the results tended to corroborate Dr. Dearborn's statement.

Two razor clam samples were submitted from Swikshak Beach (Fig. 7). Results of the bioassay revealed no detectable toxins. Unfortunately, these were the only samples submitted from this area in 1969. Seawater samples for determination of coliform densities were not obtained.

The razor clam sampling during 1969 in the Cordova area appeared significant, with P.S.P. being evidenced in whole or uneviscerated clams, but not in eviscerated co-samples. The significance of these results was further advanced by independent statements from John G. Girard (Registered Sanitarian, Head, Food Protection Section, Department of Health and Welfare, Olympia, Washington) and Duane T. Ohlsen (Registered Sanitarian, Section Director, Food Service Section, Oregon State Board of Health, Portland, Oregon). Mr. Girard stated: "There is apparently some confusion in Alaska regarding the risk of paralytic shellfish poisoning and the razor clam. We found many years ago that cleaned razor clams do not contain the toxin. The toxin is distributed in the digestive system which is totally removed in cleaning along with the gills and siphon end." Mr. Ohlsen stated : "Since razor clams are usually, if not always, eviscerated before being consumed, an added safety factor is brought into play. The toxin appears to be present only in the viscera of the shellfish. Therefore, eviscerating that shellfish appears to remove all the toxic portion of the animal."

The favorable results of the bioassays and the statements of Girard and Ohlsen did much to pave the way toward opening these beaches to commercial harvest (except those on the east side of Cook Inlet which, by regulation, are open only to sport clam digging). Although mostly favorable, the seawater samples did reveal levels of coliform bacteria that were at times, perhaps, bordering on unsatisfactory with regard to National Shellfish Sanitation Program standards.

26 Lower Cook Inlet

Cape Douglas

Four peaked l1ountai� S\vikshak @

�� Kiukpalik Island

Fig. 7. Razor clam sampling locations at the Swikshak gro wing area, south side of Alaska Peninsula. 27 The razor clam growing areas at Cordova, Swikshak Beach and Polly Creek Beach were approved for commercial harvest on April 27, 1970. Also at that date, a package of documents was submitted to the Division of Environmental Health, Juneau, Alaska, which contained signed testimony, validated studies, and a Memorandum of Understanding between the Alaska Department of Fish and Game and the Alaska Department of Health and Welfare. These documents were to be used, in part, to support a request for U.S. Public Health Service approval of the State of Alaska's Shellfish Sanitation Program so that Alaska could gain membership to the National Shellfish Sanitation Program. Unfortunately, this request lay dormant until February 1971 when action was again taken to discuss a format for acceptance of the program with officials of the U.S. Public Health Service.

April 27, 1970, was an important date in still another respect. The first "Certificate and Permit" to sell fresh and fresh-frozen razor clams "Limited to Intra-State Shipments Only" was issued to M and W Packers at Big Mummy Island, near Cordova. Subsequently, on May 18, 1970, SRS Shellfish and Bait Company of Kodiak, Alaska, and on November 3, 1970, Carl Olsen of Cordova, Alaska, were issued similar permits.

Thirty-three razor clam samples were collected from the Cordova growing area from February 26 to September 28, 1970. Establishment of key sampling stations at strategic locations rather than reliance on the saturation sampling of 1969 and cessation of submitting eviscerated clams necessitated by limitations of time, budgets, and other laboratory commitments resulted in a considerable reduction in sample size. On May 18, 1970, detectable toxins were found in samples of razor clams collected from northeast Concrete Bar [ P.S.P. (ug/1 OOg) level of 34] . Samples collected from southwest ocean bar and Little Mummy Island Bar, on thesame date, had no detectable toxins (i.e.,<32 a.t1d<33, respectively). The remaining Cordova razor clam samples contained no detectable toxins.

In addition to razor clams, other species of clams were submitted from Cordova Sector 1 during the 1970 field season; namely, butter clams (Saxidomus), little-neck clams (Pro to thaca), surf clams (Spisula), cockles (Clinocardium), and soft-shell clams (Mya). In total, seven of these " other species" were tested. On July 9, 1970, the P.S.P. (ug/1 OOg) level in whole cockles collected near Hawkins Cutoff was 33, even though no detectable toxins were found in whole razor clams, i.e., <3 2, collected from nearby Little Mummy Island Bar. The remaining hardshell samples showed no detectable toxins.

Four samples of whole razor clams were collected from Swikshak Beach from April 8 to September 18, 1970. Similarly, four samples of uneviscerated razor clams were obtained from Polly Creek Beach during the spring and summer of 1970. Bioassays of these eight samples revealed no detectable toxins. Thus, the 1970 sampling provided the second year of background data which indicated that, although P.S.P. was present in some areas, levels were well within safe limits.

Additional bioassays were performed on 33 uneviscerated razor clam samples, collected from May 15 to August 10, 1971, from the Cordova growing areas. These bioassays were conducted at the University of Alaska, Douglas Marine Laboratory, Douglas, Alaska. Hazardous ice conditions prior to May 15 precluded earlier sampling. Sampling was discontinued after August 10 when it was learned that all previous samples had been accumulating in the laboratory freezer due to lack of fu nds to conduct the bioassays. Funding did, however, become available by mid-September and by late September P.S.P. bioassays were initiated. None of the 1971 Cordova samples showed detectable levels of toxin, i.e., <41 (ug/lOOg) (the higher reading of 1971 nondetectable levels of P.S.P.

28 compared to bioassay results of 1969 and 1970 resulted from the fact that a different strain of mice was used at the Douglas Marine laboratory than at the Federal laboratory in Gig Harbor, Washington).

Fifteen razor clam samples were collected from the Polly Creek growing area May 25 to September 7, 1971. No detectable toxins were evidenced.

From Swikshak Beach three razor clam samples were obtained approximately one month apart, June 6 to August 24, 1971. No detectable toxins were evidenced. One sample was obtained from Kashvik Bay (Fig. 8; number 25) on June 26, which also showed no detectable toxins. Considerable confusion developed in regard to a sample of razor clams collected from Halibut Bay (Fig. 8; number 4 7), Kodiak Island June 12, 1971. The frozen sample was sent to the Douglas Marine Station on June 18. The date or condition (frozen or thawed) when received at the laboratory was not indicated on the bioassay sheet of the Halibut Bay sample, but on the Swikshak sample that accompanied it, the date received was indicated as "6/71." The samples were assumed to have been put immediately into the freezer at the Douglas Station. The bioassay of the Halibut Bay sample was performed on September 28, 1971, in which the gut was removed from the clams and the subsequent eviscerated sections analyzed. Intraperitoneal injections of tho extract at a dilution of 2.5 wore given to six mioo (standard bioassay proooduro); they all died from 4 minutes, 40 seconds to 6 minutes, 10 seconds following the injection with a median death time of 5 minutes, 39 seconds, thus indicating a P.S.P. level of 173 ug/lOOg. I questioned the laboratory technician at length over the presence of P.S.P. toxin in the eviscerated sections of the body. The technician's only reply was that the toxin had, perhaps, leached from the gut into the surrounding musculature. Had laboratory facilities for rapid bioassays been available at the time of collection, the present unknown status of the Halibut Bay sample would probably have easily been solved simply by immediate follow-up sampling upon notification of the test results. This, of course, was not the case and the mystery remains a mystery.

Also during 1971, an all-inclusive effort was launched to secure approval of the State of Alaska's proposed Shellfish Sanitation Program by the U.S. Public Health Service. Attainment of Alaska's membership in the National Shellfish Sanitation Program which would permit interstate shipping status for fresh and fresh-frozen razor clams to other member states, Canada, Japan and Korea was considered an important step whereby hardshell clams from approved growing areas in Alaska would eventually be given clearance for interstate shipping status.

Federal approval could be secured only after the shellfish regulatory agencies for the State of Alaska (Alaska Department of Fish and Game, Alaska Department of Health and Social Services, and Alaska Department of Public Safety) had performed six steps to develop an acceptable shellfish sanitation program.

These six steps were:

1. Establish a surveillance system to assure that razor clams would not be harvested from unapproved areas.

2. Establish a monitoring program for P.S.P. that would be effective in giving an early warning.

3. Gather all data concerning P.S.P. in razor clams. Include in this material all factual data which provides evidence that razor clams are safe to eat.

29 --- ' � '

\\ '

\\ \

\\ '

\. '

\ \ '

\\ \

13 11 \\ 15 \

\\ ' 12 10 \ 14 \ \ 17 \ \ � \

(.;) 0

Da l l

et Bea ch �:r Mass L "' � 7 -,1. :::; 1Lf17. �U" lr) r � � � �\() 46 �;pcJ'oo 4; 48 a 49 areas in ;!Iask clam growing known razor ;J cations of Geographic lo Fig. 8. 4. Develop laboratory capabilities that would enable rapid analysis of monitoring samples.

5. Evaluate growing areas in regard to pollution potential (industrial and domestic).

6. Develop a Memorandum of Understanding among the State of Alaska's shellfish regulatory agencies specifying the division of responsibility with appropriate reference to State Codes which allow each agency to promulgate rules and regulations.

I focused upon these six steps and accumulated a variety of documents and data which established that requirements for the aforementioned steps had been or were in the process of being met. This package of consolidated documents was entitled "Preparatory Activities fo r Administration of the State of Alaska Shellfish Sanitation Program." When completed, in October 1971, these documents were forwarded to the Division of Public Health in Juneau, Alaska, where they were consolidated with additional documents prepared by Mr. Ralph Borysiak, Seafood Sanitarian. Mr. Borysiak delivered the documents to Washington, D. C., in November 1971, where they were discussed and later examined by U. S. Public Health Service officials.

I later received a letter from J. David Oem, Director, Division of Shellfish Sanitation, U. S. Department of Health, Education, and Welfare, dated February 3, 1972. Dr. Oem stated in his letter, "I recently reviewed the proposed sanitary control program for Alaska razor clams and submitted our comments to Seattle. I was pleased to see the progress you are making."

Routine owassays of razor clam samples collec1ea m 1972 and 1973 from the three previously mentioned approved growing areas evidenced nondetectable and detectable levels of P. S.P., with the latter being well within safe limits. Highest counts were at Strawberry Reef, Cordova Sector 4, July 1973 with 62 ug/1 OOg in whole clams.

During May through August 1973, sanitary surveys were conducted at the Cordova, Polly Creek and Swikshak growing areas by Federal Food and Drug Administration personnel. No problems were encountered with heavy metals, coliform counts, or P.S.P.

On July 18, 1974, an interdepartmental memorandum of understanding was signed by the Commissioners of the Alaska Departments of Fish and Game, Public Safety, and Health and Social Services. This agreement spelled out the division of responsibility among the above three agencies serving to control the State of Alaska Shellfish Sanitation Program .

The Alaska Department of Public Safety will physically patrol all approved and unapproved razor clam growing areas. The Alaska Department of Fish and Game will procure and submit clam and water samples for analysis on a routine basis. And the Alaska Department of Health and Social Services will maintain activities in pursuance with the balance of the fe deral guidelines ; namely, to provide laboratory facilities and personnel for analyses of clam and seawater samples, and to conduct sanitary surveys of razor clam growing areas on a regular basis. The latter agency will maintain overall responsibility for the Program.

On July 31, 1974, public notice was issued by the Alaska Department of Health and Social Services regarding proposed changes in the regulations of that Department. Title Seven of the Alaska Administrative Code, Chapter 15, Sections 310 - 3 70 were amended to provide language and methodology consistent with the National Shellfish Sanitation

31 Program to satisfy requirements of the U. S. Food and Drug Administration. These regulations govern commercial harvest, processing, and distribution of razor clams for human consumption and control commercial bait harvest of all bivalve mollusc shellfish to protect the public health.

Public hearings on the above changes to the shellfish regulation were held during September, 1974. As a result of these hearings, Lt. Governor Lowell TI10mas, Jr., signed into law on December 11, 1974, the revised regulations which became effective on January 10, 1975.

On February 24, 1975, Alexander M. Schmidt, M.D., Commissioner of Food and Drugs, U.S. Food and Drug Administration advised Frederick McGinnis, Commissioner of the Alaska Department of Health and Social Services of F.D.A. acceptance of the Alaska Shellfish Sanitation Program and recognized Alaska as a full cooperating State participant in the NSSP.

32 RAZOR CLAM BIOLOGY

Distribution of Razor Clams in Alaska

Razor clams (Siliqua patula, Dixon) are found from Southeastern Alaska to the Bering Sea and the Aleutian Islands (Fig. 8). Coexistent with S. patula, though occupying a zone comprised of finer substrates (R. Baxter, Fishery Biologist, ADF&G, Bethel, Alaska, pers. comm.), is S. alta which has been observed from Augustine Island in Lower Cook Inlet westward to Kodiak Island and the Alaska Peninsula. Of the two species, S. patula is more prevalent in the growing areas noted and is by far the most sought after for human consumption.

The northernmost commercial razor clam beaches of British Columbia are located on the Masset beaches of Graham Island in the Queen Charlotte Group. Pifty miles to the northwest of Masset lies Dall Island, Alaska, where Baxter (op. cit.) believes there may be a razor clam bed, although this remains unsubstantiated. However, several small beds of razor clams are extant on the east coast of Kruzof Island (#1 ) (opposite Sitka). The total of all the growing areas there is approximately one beach-mile. Abundance is described as fair (J. Parker, Fishery Biologist, ADF&G, Sitka, Alaska, pers. comm.), but digging is restricted to recreational interests.

Razor clams are next encountered at Dixon Harbor (#2), located in Glacier Bay National Monument, 55 miles northwest of Hoonah. This bed lies near the mouth of a small stream situated behind the first point of land after entering the bay at its northwest side. The extent of the growing area is approximately 1/2 mile, and according to Baxter (op. cit.) abundance consists of subsistence quantities only.

Conrad (1838; In Weymouth et al. , 1925:202) referred to razor clams being found at Lituya Bay. However, Baxter (op. cit.), in his canoe trip along the southeastern coast of Alaska in 1960, reported that although razor clam shells occasionally were found washed up on the beach from Li tuya Bay to Ocean Cape (# 3), he was unable to procure live specimens. Abundance of razor clams is unknown in this area which is described as exposed, sandy, surf-swept beaches.

Baxter (op. cit.) noted a small, sandy beach by a slough opposite the town of Yakutat (#4) that contained S. patula. This beach is only 20 yards wide and contains subsistence quantities only.

In Icy Bay (#5), Baxter (op. cit.) found shells of razor clams washed up on the beach, but procured no live specimens. The extent and abundance of razor clams in this area are unknown.

Approximately 32 miles east of Cape Suckling, near the mouth of the Seal River, Baxter (op. cit.) found a small, inaccessible sand beach (#6) containing razor clams. The extent of the beach was about 200 yards and abundance was described as being subsistence quantities only.

From Cape Suckling to Orca Inlet, including the adjacent beaches of Kayak, Kanak, and Hinchinbrook islands, are the historically commercial razor clam growing areas of Cordova (#7) with a productive extent of approximately 140 miles.

Small, scattered beds of razor clams are known to exist in Prince William Sound. On the outside beach at Nuchek (#8), Port Etches, Hinchinbrook Island, a few specimens

33 of S. patula are reported to have been washed up on the beach following storms. This population is thought to be minimal, probably at the subsistence level. Since the 1964 earthquake, razor clams on Montague Island have been found only at Jeanie Cove (#9), where the growing area is broken into small, sandy beaches bordered by rock, and in Hanning Bay (#1 0). The total growing area at each location is approximately 1 mile and abundance is barely enough for subsistence. Razor clams were found at MacLeod Harbor (#1 1) prior to the 1964 earthquake, but none have been reported there recently. Otto Koppen, a resident of the Cordova area for over 50 years and former Federal Enforcement Agent, reported (pers. comm.) finding a small bed of razor clams on a sandy beach at the northeast side and near the head of Eaglek Bay (#12). This report has not been confim1ed.

At the southwest end of Nuka Island (#1 3), adjacent to the southeastern entrance of Cook Inlet, is a small, sandy beach, perhaps 1/2 mile in extent, that supports a few razor clams at the subsistence level. Immediately east of Nuka Island, from Gore Point to Tonsina Bay (#1 4), Baxter (op. cit.) found razor clam shells on the beach, some with adductor muscles still attached. This area is described as a rocky coast with scattered sandy beaches; abundance is unknown.

MacDonald Spit (#15), in Lower Cook Inlet about 5 miles northeast of Seldovia, contains a bed of razor clams to an extent of 1 mile, but at subsistence levels only. Across Kachemak Bay fr om MacDonald Spit is the Homer Spit and the eastside beaches of Cook Inlet. Razor clams are found from the Homer Spit northwest to Anchor Point and thence northeast to Cape Kasilof (#16), a total distance of approximately 65 miles. Abundance varies considerably, being at the subsistence level from Homer to Anchor Point and "sparse to moderate" or "very abundant" from the Anchor Point vicinity to Cape Kasilof according to D. Nelson (Sport Fish Biologist, ADF&G, pers. comm.). Nelson fu rther indicated that there are no razor clams north of Cape Kasilof on the eastside beaches. Prior to 1960, a segment of the eastside beaches represented a commercially harvested growing area, particularly in the Ninilchik area.

The major portion of the razor clam growing area on the west side of Cook Inlet extends fr om Kustatan, at the West Foreland, southwest to the base of Rusty Mountain in Tuxedni Bay ( #17), a distance of about 55 miles. Abundance varies, with subsistence levels from Kustatan to the mouth of the Drift River where the beaches are generally rocky to "sparse to moderate" or "very abundant" (Nelson, op. cit.) from the mouth of the Drift River to the base of Rusty Mountain. Polly Creek Beach, a longtime commercial harvest area, is in this district. A fair bed of razor clams, approximately 2 miles in extent, is located along the north shore of Chinitna Bay ( #1 8). Nelson (op. cit.) describes the density of clams in this bed as "very abundant." Baxter (op. cit.) reported a "fairly abundant" bed of S. patula, approximately 1000 yards in extent, at the south shore of Augustine Island ( #1 9), with beds of S. alta nearby. West of Augustine Island is the abandoned village of Amakdedori. Baxter (op. cit.) found razor clam shells in this area, but procured no live specimens.

At the southwest entrance to Cook Inlet lies Cape Douglas, below which, for 25 miles, is the razor clam growing area designated as North Swikshak (#20). Razor clams are in excellent abundance in this area according to J. Lechner (Regional Supervisor, Commercial Fisheries Division, ADF&G, pers. comm.). Lechner described most of the other razor clam growing areas in the following account and D. Lall (former Regional Research Supervisor, Comm. Fish. Div., ADF&G, pers. comm.) described others except as noted. Southeast of the unnamed cape lying abeam of Fourpeaked Mountain is the 20-mile expanse of South Swikshak Beach (#21) where clam abundance is also regarded

34 as excellent. Both North and South Swikshak beaches are commercially utilized and are historically important growing areas.

Rallo Bay (#22) contains commercial quantities of clams along a 7-mile expanse at the northwest end of the bay. South of Rallo Bay is Kukak Bay (#23), historically important as a commercial growing area, with 10 miles of beach yielding excellent abundance. Dakavak Bay (#24) contains 3 miles of beach with good commercial abundance, and nearby Kashvik Bay (#25) has 2 miles of beach containing excellent abundance that has been commercially utilized. Alinchak Bay (#26) has 4 miles of beach yielding good abundance that has been commercially utilized. Imwya Bay (#27), by Kilokak Rocks, though having excellent abundance on a 2-mile beach has not been commercially harvested. Chiginagak Bay (#28) contains good abundance on a 2-mile beach and has been commercially utilized. Yantarni Bay (#29) has 10 miles of beach containing excellent abundance and has been commercially utilized. Aniakchak Bay (#30) has 5 miles of beach with excellent abundance that has also been commercially utilized. Immediately inside of Cape Kumliun lies Hook Bay (#31) with 1 mile of growing area containing good abundance that has not been commercially utilized. About 10 miles west by southwest of Perryville is Humpback Bay (#32) which, according to H. 0. Kaiakonok (Perryville resident, pers. comm.), contains razor clams. Neither their extent nor abundance is known. San Diego Bay (#33), at the west shore of Stepovak Bay, has a growing area 2 miles in extent which contains "possible commercial quantities" according to G. Davenport (Area Management Biologist, Comm. Fish. Div., ADF&G, pers. comm.). Izembek Bay (#34), located 10 miles north of Cold Bay and facing the Bering Sea, has a growing area 22 miles in extent containing commercial quantities (Davenport, op. cit.). Bechevin Bay (#35) at the northeast corner of Unimak Island and also fronting on the Bering Sea, contains commercial quantities along 10 miles of beach (Davenport, op. cit.). Kalekta Bay (#36), at the northeast corner of Unalaska Island and facing Akutan Pass, contains 1 1/2 miles of beach which Davenport (op. cit.) rates as "possibly fair" for abundance. Kalekta Bay is the furthest westward razor clam growing area that has been documented in the Aleutians.

The Kodiak Archip elago, to the northeast of the Alaska Peninsula and Aleutian Islands, also possesses some razor clam beaches.

Duck Bay (#37), on the southeast coast of Afognak Island, has a 1/2-mile stretch of beach which, prior to the 1964 earthquake, was commercially utilized. Since then, commercial effort has waned and abundance is now described as fair.

Buskin Beach (#38), near the city of Kodiak, has 1 mile of growing area described as poor. This area is used to some extent by recreational diggers only. Middle Bay ( #3 9) has good abundance on its meager 1/2 mile of available growing area and is also limited to recreational digging. Three growing areas are located on the north shore of Ugak Bay : surf-swept Narrow Cape (#40) at the mouth with 5 miles of poor abundance; and Portage Bay (#41) and Saltery Cove (#42) nearer the head, each containing 1/2 mile of growing area with abundance rated as fair and poor, respectively. None of these three areas has been utilized to any extent since the 1964 Good Friday earthquake. There are two growing areas on Sitkalidak Island : Ocean Beach (#43), which is fu lly exposed to the Gulf of Alaska and Rolling Bay (#44 ), sheltered by Black Point at the southeast end of the island. These beaches contain 3 and 1 miles of growing area, respectively, and both are described as having fair abundance. At the south side of Tugidak Passage and on the Tugidak Island side (#45) are 10 miles of growing area with abundance rated as fair. Although no longer commercially utilized, this area was once harvested but was subsequently abandoned due to the small size of the clams.

35 At the extreme southwest end of Kodiak Island, between Cape Alitak and Low Cape (#46), are 10 miles of growing area described as fair ; this area has been commercially utilized. Bumble Bay (#47), located on the southern base of Cape Ikolik, contains 2 miles of formerly utilized commercial growing area regarded as fair. A few miles to the north, between Middle Cape and Cape Grant, is another formerly utilized commercial area at Halibut Bay (#48), which contains 5 miles of beach with good abundance. Carmel (#49), an area 2 miles in extent, lies midway between Cape Grant and the mouth of the Sturgeon River. Abundance there is reported fair, but the area has not been commercially utilized.

Thus, there are 49 locations in Alaska where evidence of razor clams is known to exist; approximately 50 percent of these are capable of sustaining commercial operations on the low tide terrace to varying degrees. Perhaps in the near fu ture the extent of subtidal razor clam stocks in the aforementioned areas will be known which may, in turn, open a vast fishery of previously unirnagined scope.

Razor Clam Life History Studies

Methods

In the spring of 1969, 10 study sites were established within the razor clam growing area of Cordova Sector 1 to collect vital life history data, study population dynamics and habitat relationships, and determine accurate censusing methods for management of various razor clam populations in Alaska. There was an urgent need for this information as there had been no major research efforts on Alaska razor clam stocks since 1928. These earlier efforts did not deal with formal censusing nor life history information, but instead had been directed mainly at age/length studies.

Objectives of the initial investigations were : (1) to explore some facets of razor clam life history ; namely, sexual characteristics, spawning, growth rates, and age-length-weight relationships; (2) to increase our knowledge of population dynamics and habitat relationships by obtaining estimates of frequency of occurrence of razor clams by tide level as well as age, length and growth increment by tide level ; (3) to obtain estimates of fecundity, mortality and survival; (4) to analyze tidal currents and their possible effect on larval drift and relocation of razor clams on the low tide terrace; (5) to determine the effect of substrate and exposure on razor clam density and survival; and (6) to evaluate various censusing methods.

The hypothesis, upon which I based this investigation, was as follows: "Each razor clam bearing beach or bar is, in itself, a habitat possessing unique features, but whether protected from or directly exposed to the pounding of breakers or to strong tidal currents, razor clam populations have a characteristically common behavioral structure that can be defined, and although this structure may appear to vary, the variance is merely a reflection of physical interactions of meteorological and hydrological phenomena, which also can be defined."

The study area within Sector 1 encompassed the southwest portion of Orca Inlet and the inside waters of the Egg Island-Ocean Bar complex shown previously in Fig. 3, page 21. Two of the 10 study sites were subsequently abandoned during the field season of 1969. One was destroyed by tidal currents and the other was difficult to reach due to its location at the head of a shallow gutter, and difficult to dig because of the poor drainage characteristics of the bar.

36 The remaining eight sites were stable and accessible throughout the primary study phase. At each site, tide levels were determined by readings with hand level and leveling rod in conjunction with appropriate references to local tide tables. Orca Inlet is completely protected from breaker action and on calm days the water surface is glassy smooth (Plates 1 and 2). Thus, at the water's edge on such days, there is very little surge and usually only a slight lapping, thereby facilitating the general establishment of the tide levels. Final determination of tide level locations was made after repeated observations indicated very close agreement with each other and with tide tables. Exceptions to the above observations were attributed to wind, either holding the tide in or out, or to seiches generated by seismic activity (an earthquake was felt in the Cordova area on April 19, 1969). Depending upon the height of the bar, tide levels were located from -3 to +5 feet (-0.91 to +1 .52 m) in contour elevations relative to mean lower low water (U.S. Pacific Coast Datum Plane) which was referred to as the 0 (zero) fo ot or meter tide level. Study plots were established at each tide level. They measured 10 by 100 feet (3.048 by 30.48 m), with their long axis being parallel to the water's edge and the respective tide level laying 5 fe et (1.52 m) from the upper and lower boundaries, res ectively (Plates 3 and 4 ). Thus, each plot contained an area of 1000 sq. ft. (92.9 m� ). A complete description of each site and its respective study plots is provided in Appendix 2. Relative profiles of each site and diagrams of the study plots are shown in appendices 2a to 2i.

As stated earlier, study plots utilized in this phase of the investigation were establishedI on protected beaches and bars, that is those completely devoid of breaker action but subject to tidal currents ranging from weak (little or no turbulence) to strong (heavy turbulence and whirlpools). It must be remembered, however, that Orca Inlet is not always placid, for 12- to 15-fo ot (3.66 to 4.57 m) seas are generated during violent storms.

Boundaries of each study plot were marked with either steel reinforcement rods measuring 1/2 inch by 5 feet (2.54 em by 1.52 m) that were driven into place with a sledge hammer or, in most cases, by 6-foot (1.83 m) sections of spruce saplings which ranged in diameter from 2 to 4 inches (5.08 to 10.16 em). These were readily inserted into place after drilling a hole 4 feet (1.22 m) deep in the sand with an ice auger. Stout nylon twine was used to mark the perimeter of each plot, fastening it tautly about the fo ur comer posts. ) Following establishment of the study plots, all razor clams and other mollusc species were to be removed from each plot. However, because of time limitations plots at the -2 and -3 foot (-0.61 and -0.91 m) tide levels could not be adequately sampled for frequency of occurrence of razor clams due to the lessened frequency of minus tides. A record was kept of the date, time spent digging, weather and sea conditions, composition of ) the biological community and age, length, weight, growth increment, and shell and sexually related characteristics of all razor clams by tide level. Each plot was dug, using a razor clam shovel, repeatedly over a 3- to 5-month period, depending upon the site, until no further evidence existed that additional clams were present, except as noted above for the -2 and -3 foot tide levels. It was suspected, however, that a residual population remained in each plot which was probably composed of smaller clams whose "shows" ) (refer to Glossary) were not readily apparent. Therefore, 10 percent of each plot was subsequently screened to a depth of 1 fo ot (0.3048 m). That is to say, 100 cu. ft. (2.83 m3 ) of substrate in each plot was sampled by washing it through a fine-mesh screen. This aspect of the study will be discussed in detail in the following section, Population Dynamics and Habitat Relationships (Page 87 ).

Supplemental information and supportive data relative to razor clam biology were collected ) from P. S.P. sampling stations located at Cordova Sector 4 and Point Steele Beach,

37 ) Pla te 1. Aerial Flew of the south1vest portion of Orca Inlet, Cordova, Alaska, looking easterly. Little Mu mmy Island lays at left center; Big Mummy Island, center; and Filipino Island at righ t center. Heney Range of the mainland lays in th e backgro und.

38 Pla te 2. Aerial view of the southwest portion of Orca Inlet, Cordova, Alaska, looking southerly with Poin t Bentinck, Hinchinbrook Island at upper righ t.

39 Plate 3. Aerial view of th e study site at Rocks/ide Bar Orca Inlet with th e +4 to + 1 fo ot (+!. 22 to +0. 30 m) tide level study plots exposed.

40 Pla te 4. Aerial Fiew of th e study site at Little Mummy Is land Bar, Orca Inlet, showing the +3 to th e -3 fo ot (+0. 91 to -0. 91 m) tide leFel study plots.

41 Hinchinbrook Island (Fig. 9). Results of these razor clam life history studies are as follows.

Sexual Characteristics

Knowledge of sexual characteristics and time of spawning is of value in managing razor clam populations. Prior to this study, little or nothing was known in Alaska of razor clam sex ratios, rate of growth by sex, attainment of sexual maturity relative to age and size or spawning. The following is a refinement in knowledge of razor clam sexual characteristics and should be of value in the fu ture management of these populations.

Subsequent discussions deal with aging technique and sex determination technique. The former is adequately discussed by: Weymouth et al. (1925); Frazer (1930); Weymouth and McMillin (1931); Thompson and Weymouth (1935); Hirschhorn (1962); and Bourne and Quayle (1970). The latter is adequately discussed by: Loosanoff (1937); Quayle (1943); Tegelberg (1961); Hirschhorn (1962); Ropes and Stickney (1965); and Bourne and Quayle (1970).

Sex ratio information was obtained by collecting a total of 567 razor clams from eight study sites in the Cordova area. These clams were tabulated by sex according to the sites from which they were obtained. Results of chi-square tests applied to these data indicate, in most instances, no significant departure from a I:I ratio (Table 3 ). One possible reason that Site 6 showed significance at the 5 percent level of probability will be discussed briefly here. Under Survey Techniques, page 152, I discuss certain variables that are linked to razor clam "show." Limited data reveal that other variables, not yet defined, appear to exist causing one sex to "show" more prevalently than the other under certain conditions. It may be that certain collection periods at Site 6 coincided with this phenomenon.

In comparing growth of males versus females, a sample of 167 razor clams was obtained from study sites in the Cordova area. This sample, representing nearly equal proportions of males and females of the 1963 year-class, was examined for contrasting growth patterns. Variance ratio and "t" tests indicated no significant difference between annual increments from the first to the sixth annulus (Table 4 ).

Approximately 600 razor clams were collected from Cordova Sectors 1 and 4 to study age, length, sexual maturity and related dimorphism. Microscopic examination of living generative cells of 501 razor clams from Sector I revealed that some individuals become sexually mature by their third year of life. That is to say, following formation of the third annulus (age 2 I /2 years) and when seasonal growth is again resumed, sex cell differentiation and development are evidenced in a certain proportion of clams approaching their third full year of life. This may occur from May to September, depending upon when they were initially spawned. The frequency of maturity in a given sample increased as the clams became older. All were sexually mature in their seventh year of life at a mean valve length of 123.64 ± I 0.54 mm. Mean lengths were obtained by measuring the outermost annulus that had been formed prior to the next season's growth period.

At Sector 4 no sexually mature razor clams younger than 4 years old were encountered, and all clams older than 5 years were sexually mature. Only 104 clams from Sector 4 were examined for maturity, however, and it may well be that the observed abrupt maturation was a result of insufficient sample size. These findings for Sectors 1 and 4 are in agreement with those of Weymouth et al. (1925).

It was particularly interesting that size and growth rates were significantly different between

42 u u u u u

145° SO ' COPPER RIVER

.. • •· . ISLAND ·"'O DIJt;)� C

PR INCE WILLIAM

Sca le: 2.54 em 16. I km

�c!J EGG +:> ISLANDS w

60° 10' BOSWELL BAY

P 0 I NT B ENTI NC K SECTOR #4

GU LF OF ALASKA � CAP E SUCKLING

Fig. 9. Razor clam gro wing areas of Co rdova, Alaska, Sectors 1 and 4. Table 3. Sex ratio of mature razor clams from eight study plot sites in Orca Inlet, Cordova Sector 1.

Study Plot Site and Corresponding Number of Oams

Site Site Site Site Site Site Site Site Sex 2 3 4 5 6 7 9 10

Male 47 26 28 9 46 31 67 14

Female 41 29 21 17 72 35 60 24

Chi-Sguare Test with Yates' Correction

Observed Results Critical Values of x2

x2 (v 1) x2o.95 x2o.99

Site 2 0.2840 <

Site 3 0.0727 <

Site 4 0.3 747 <

Site 5 1.8846 <

Site 6 5.2966 > <

Site 7 0.1364 <

Site 9 0.283 5 <

Site 10 2.1316 <

Total 1.5873 <

44 Table 4. Comparative growth of males versus females in Cordova Sector I for members of the 1963 cohort.

Mean Length mm Annulus Number Male Female Variance Ratio

7. 1429 6.9880 F = 1.3628 < F.95

2* 25.4286 26.3373 F = 1.4634 > F.95; < F.99

3 46.5000 47.0602 F 1.1756 < F.95

4 73.9167 72.9398 F = 1.0323 < F.95

5 97. 1 429 96. 1687 F = 1.2689 < F.95

6 114. 1190 112.0482 F = 1.0943 < F.95

* t (v 165) = 0.8596 < 1.96 t.05

Conclusion: No significant difference between annual increment of males and females to age 5.5.

Sample Numbers

Males = 84

Females = 83

45 sexually mature and immature members of the same year-class (Tables 5 and 6). Attainment and degree of sexual maturity definitely appears to be more related to valve length than age. That is, there is a closer correspondence between the length-maturity relationship than the age-maturity relationship. This agrees with similar findings by Frazer (1930), Bourne and Smith (1972), and Quayle and Bourne (1972).

Spawning

Weymouth, McMillin, and Holmes (1925) suggested that the mm1mum spawning temperature for the razor clam was about 13° C (55.5° F); and Frazer (1930) concurred with this conclusion. Bourne and Quayle (1970) concluded that some spawning occurs below 13° C at Masset beaches and Long Beach, British Columbia. This conclusion was based on surface water temperature recordings made at Langara and Triple islands, B. C., and at Amphitrite Point, Vancouver Island, B. C. Unfortunately, no recordings of the water temperatures over the intertidal beaches, nor of the sand at either Masset beaches or at Long Beach were taken. Consequently, I conducted a study to gain more precise knowledge of the dynamics of spawning activity relative to time and seawater temperature.

From May 20 to September 26, 1969, a total of 1,146 razor clams, from weekly collections at Cordova Sector 1 study sites, were examined to assess ripeness of gametes and monitor spawning activity . Microscopic examination of living gonad tissues revealed sex and relative degree of ripeness based on size of ova or development and proliferation of spermatozoa.

Females possessing numerous ripe ova, greater than 90 microns in diameter, were considered to be fully mature. Males having numerous spermatozoa (many motile) with well-developed heads and tails were considered to be fully mature. In addition, I recorded a condition factor reflecting texture of gonad tissues. Prior to full ripeness and before actual spawning activity was noted, the texture of gonadal material was firm and unyielding to a scalpel scraped over exposed portions. Conversely, in specimens classified as fu lly ripe which were collected when spawning activity was in progress as evidenced by field inspection of razor clams spawning in the natural environment, sex elements yielded in a fluid manner and ova flowed freely and individually on the blade of a scalpel to which a drop of water had been added.

Depletion of gonadal products was expressed as a percent of active spawning progress. The latter was measured by visually estimating, in five stages, the relative percent volume of the gonad (after splitting the latter) occupied by gametes. The five stages corresponded to 0, 25, 50, 75 and 100 percent fu llness.

The primary goals of the spawning study were to determine approximately when spawning was initiated, the duration of the spawning period and to what extent seawater temperature and time correlated as variables. Subsequent observations tended to verify the initial findings. Further documentation is provided in studies conducted by Tegelberg (1961), Hirschhorn (1962), and Bourne and Quayle (1970).

Seawater temperatures in Cordova Sector 1 were measured with a Ryan submersible thermograph placed just below the substrate surface on a razor clam bearing bar at the -1 foot (-0.3 m) tide level (relative to mean lower low water) in conjunction with U.S. Coast and Geodetic Survey recordings taken at the Cordova tide station 2 m below the water surface. There was no significant difference (t<.95) in mean temperatures by time period between the two recording sites located 5.96 miles (9.6 km) apart.

Multiple regression analysis utilizing the variables of spawning progress X 1 , seawater

46 Table 5. Analysis of age, length, sexual maturity and related dimorphism for razor clams in Cordova Sector 1; length measured at the last annulus formation.

Immature with increment on the nth annulus Median Mean Standard Number Annulus Age Length Length Deviation in Number (Years) (mm) (mm) (mm) Sample

1 0.5+ 2 1.5+ 32.98 31.05 9. 19 22 3 2.5+ 46.00 47.55 10.17 66 4 3.5+ 66.25 66.60 10.99 25 5 4.5+ 85.75 86.99 8.46 15 6 5.5+ 1

Mature with increment on the nth annulus Median Mean Standard Number Annulus Age Length Length Deviation in Number (Years) (mm) (mm) (mm) Sample

3 2.5+ 62.20 61.14 9. 10 14 4 3.5+ 84.40 83. 13 13.29 46 5 4.5+ 97.99 98.25 11.84 142 6 5.5+ 113.98 113.98 10.60 170

Analysis of Sexual Dimorphism

X length at annulus 3, immature versus X length at annulus 3, mature

t (v78) = 4.6188 > 2.6492 t.99

X length at annulus 4, immature versus X length at annulus 4, mature

t (v69) = 5.3060 > 2.6546 t .99

X length at annulus 5, immature versus X length at annulus 5, mature

t (v l55) = 3.5830 > 2.60 t .99

Percent of maturing individuals with increment on nth annulus

Annulus Annulus Annulus Annulus Annulus Annulus 2 3 4 5 6 7

% Immature 100 82.50 35.21 9. 55 0. 58 0 % Mature 0 17.50 64.79 90.45 99.42 100

47 Table 6. Analysis of age, length, sexual maturity and related dimorphism for razor clams in Cordova Sector 4; length measured at the last annulus formation.

Immature with increment on the nth annulus

Median Mean Standard Number Annulus Age Length Length Deviation Ill Number (Years) (mm) (mm) (mm) Sample

1 0.5 2 1.5 3 2.5 44.50 45.26 9.39 9 4 3.5 57.00 57.20 7.91 10 5 4. 5 67.00 65. 14 8.31 14 6 5.5

Mature with increment on the nth annulus

Median Mean Standard Number Annulus Age Length Length Deviation in Number (Years) (mm) (mm) (mm) Sample

1 0.5 2 1.5 3 2.5 4 3.5 66.75 66.40 6.31 20 5 4.5 79.99 78. 14 8.22 28 r 0 5.5 91.99 89 . 96 7.08 23

Analysis of sexual dimorphism

X of annulus 4 immature versus X of annulus 4 mature

t (v28) = 3.4602 > 2. 76 t .99

X of annulus 5 immature versus X of annulus 5 mature

t (v40) = 4. 8144 > 2. 70 t.99

48 temperature x2, and time x3 (days, beginning June 1, 1969) yielded highly significant results. Three analyses were run, with the dependent variable X 1 being: (1) percent of razor clams that had not begun to spawn at time t; (2) percent of razor clams that were actively spawning at time t; and (3) percent of razor clams that were completely spawned at time t, respectively. Figs. 10, 11, and 12 depict these data and provide the necessary regression for each curve. As evidenced from these regressions, approach to the threshold of spawning is governed both by time and temperature. After spawning activity has begun, its progress appears to be primarily a fu nction of temperature, and completion of spawning is then a function of time. If an extrapolation is performed utilizing the equation in Fig. 11, it is found that 100 percent of the clams "would have" completed spawning by day 131, that is to say October 9.

It should be emphasized at this time that much variation in spawning activity was noted throughout the season and some individuals with mature, distended gonads showed no sign of spawning by late September.

One can use the results of the regressions in Figs. 1 0, 11 and 12 divided by 1 00 as an estimate of the parameter p in the binomial distribution to estimate, for example, the proportion and its variability in a sample of n clams which had or had not spawned, or were actively spawning.

The highest seawater temperature recorded in Cordova Sector 1 during 1969 was 55° F. This temperature was attained on August 7, 8, 9 and 10 and, as shown by the points in Fig. 11, spawning activity peaked just prior to this period.

Spawning appeared to be initiated following sustained seawater temperatures between 42° F. and 48° F. (averaging 45.22 ± 1.52°) for a 30-day period immediately prior to the commencement of spawning activity. An abrupt rise above this average to 4 7° F. (8.3° C.) appears to have triggered spawning. For example, on May 12 the seawater temperature was 42° F. The temperature steadily increased to 48° F. on May 26 after which it decreased rapidly to 44.5° F. on May 31. From this time until June 10 the temperature increased only 1.25° F., but by June II it had risen rapidly to 4 7° F. whereupon spawning began. Seawater temperatures remained above 4 7° F. from June 11 to September 30, 1969.

There appears to be a cumulative temperature factor involved with spawning and, if so, the data suggest that when this factor is satisfied, the triggering or critical seawater temperature is about 47.00° F. (8.3° C.). Nelson (1928) and Loosanoff (193 7) discussed critical spawning temperatures in other groups of pelecypod molluscs.

A second study dealing with spawning was conducted during 1971 to analyze spawning activity on a weight-loss basis. Hirschhorn (1962) noted weight loss during spawning of razor clams. Weights, lengths, and ages of razor clams from Cordova Sectors 1 and 4 were measured once during April, bimonthly from May through September, and once in October. Only clams without observed injury were used in this analysis. As seen in ) Figs. 13 and 14, there was a very apparent difference in the time and rate of weight loss attributed to spawning between the two areas.

Spawning activities in 1971 for Cordova Sector 4 clams appeared to commence sometime between May 15 and June 19, and Sector 1 clams appeared to commence spawning between July 5 and July 24. In each instance, spawning activities may have begun earlier, ) but weren't detectable because of the time lag between collections of samples. A thermograph was planted at Sector 4 on June 19 at the -1 fo ot (-0.3 m) tide level where

49 ) Seawater temperature °F.

45 52 53 53 5 3 52 50 49

Xj = -10 30 . 95337 + 37 . 23863X 2 -0 .005:? 5 X -0 .01583 X2 X3 100 �

Rl.23 = 0.9953

S I . 23 = 5. 1735

lf1 lf1 80 (j) I_ Ol 0 I_ o_

Ol 0 c - I \ c 60 3 fD o_ lf1

+- c (j) u Vl I_ 0 (j) o_ 40

20

0

20 40 60 80 100 120 Time (days from June I , 1969 ) June June July J u Jy ALg. Sept. Sept. 28 I 20 10 30 19 8

Percent of razor clams that had not begun to spawn at time t. Fig. 10. S eawater temperatu re °F. 45 52 53 53 53 52 50 49

X J 1281.63550 -43.25449 X2 + 0.00730 X 100 �

0

(j) (j) so , ------\ R . 23 = 0.966 8 Q) I L OJ 0 SJ.23 = 9.2109 L I I \ Q_ OJ c I ,... \ 0 - I c 3: 60 ro Q_ (j) +- c Q) () L v. Q) Q_ 40 v

20 0

120 20 40 60 80 JOO Time (days from June J, 1969) June June J u I y jul y Aug . Sept. Sept. 20 10 30 19 8 28 I

Fig. 11. Percent of razor clams that were actively spawning at time t. Seawater temperature °F . 45 52 53 53 53 52 50 49

X 1 = -1.84428 0.00596 X JOO + �

R I . 23 = 0.9525

S I • 23 = 8. 9292

Ul Ul 80 Q) L OJ 0 L 0... OJ c - c 3 60 !D 0... Ul +- c Q) u Vl L N Q) Q_ 40

20

0

20 40 60 80 100 120

Time (days from June I ' 1969) June June July July Aug. Sept. Sept. I 20 10 30 19 8 28

Fig. 12. Percent of razor clams that were completely spawned at time t. 300

n = 187

L 150mm

200

L 140mm

OJ

+- ..c OJ

(1) +- 0 1- L 120mm

100

L IIOmm

L IOOmm

N -<:t N ro L(\ N L(\

. - >- . . L c OJ +- 0.. ::J ::J ::J ::J ()

100 200 300

Time (days beginning January I , 1971)

Fig. 13. Change in weigh t by time period fo r razor clams at specifi c valve lengths collected from Cordova Sector 1, 1971.

53 300

n = 134

L 150mm

200

Ol L 140mm

-+- L Ol Q) 3: L 130mm ro -+- 0 f-- L 120mm 100

= L IIOmm

L IOOmm -----

(J\ li"\ r- Q) >-- L. >-- c Ol 0.. ro ::J ::J ::J

100 200 300 Time (days beginning January I, 1971)

Fig. 14. Change in weigh t by time period fo r razor clams at specific valve lengths collected fr om Cordova Sector 4, 1971.

54 the seawater temperature was 4 r F. The temperature remained constant until June 23 when it rose abruptly to 51.75° F., then dropped to 48.50° F. where it remained until June 25 when it rose again to 53.00° F., dropped ovemight to 47.25 ° F., rose to 53.50° F. on June 26 then declined gradually to 46° F. on July 4. Subsequently, the temperature rose again to 55.00° F. on July 11. The thermograph was then lost after being replaced and fu rther records are not available. The rises in temperature coincided with periods of extreme minus tides, i.e., to -2.6 feet (-0.8 m). Therefore, I feel that these higher temperatures probably reflected the warming influence of the drained, sun-warmed beach.

The average seawater temperature in Cordova Sector 1 for the 30-day period, May 12 to June 10, 1969, immediately preceding the observed onset of spawning was 45.22 ± ° 1.52 F. The onset of spawning during 1971 was suspected to have commenced at some time between July 5 and July 24. A comparison of the 30-day period average temperatures of Sector 1 from May 12 to June 10, 1969, and from June 8 to July 7, 1971, indicated temperatures were not significantly different, i.e., t = 0.97

Visual observation of the gonads of 60 Sector 4 and 45 Sector 1 razor clams collected August 7 and 11, respectively, indicated that overall depletion of sex cells in clams from both sectors was approximately 80 percent. Thus spawning was assumed to be nearly complete in both sectors by this time. Estimates of spawning progress in Cordova Sector 1 on August 11 (i.e., day 72; 51.50° F.), using regression equations in Figs. 10, 11 and 12, indicate that 29.05 ± 8.92 percent of the clams had completed spawning; 51.14 ± 9.21 percent were actively spawning; and 15.42 ± 5.17 percent had not begun to spawn. Thus, the regression estimates indicate a shift from mid to terminal spawning activity had occurred.

Estimates using regression equations in Figs. 10, 11 and 12 indicate that at least 27 percent (.99 C.I.) of the clams in Cordova Sector 4 had begun to spawn by June 24 ; at least 89 percent (.99 C.I.) were spawning by July 11 and, at most, 35 percent (.99 C.I.) had completed spawning by the latter date.

Another thermograph at Point Steele Beach on Hinchinbrook Island, 50 miles (80 km) northwest of Cordova Sector 4 and 4 miles (6.4 km) southwest of Orca Inlet, recorded seawater temperatures at mean lower low water ranging from 47.00° F. to 47.50° F. from June 8 to June 20, 1971. During the initial phase of the low tide cycle, on June 21 and 22, the seawater temperature increased slightly, ranging from 47.00° F. to 48.50° F. The last phase of this low tide cycle was similar to those at Sector 4 in regard to abrupt temperature increase. For example, on June 23 the seawater temperature rose from ° 47.50 F. to 50.00° F. , declined to 48.00 ° F. and abruptly rose again to 50.75° F. on June 24, then it declined to 50.00° F. and remained constant until the 26th when it rose again to 53.00° F. Then the temperature gradually declined to 49.00° F. on July 2. Subsequently , the temperature rose again to 51.50° F. on July 8. This thermograph was also lost after being replaced. Thereafter, U. S. Coast and Geodetic Survey recordings at the Cordova tide station, Sector 1, were used for the remainder of the observations. These data are presented in Fig. 15.

55 Fig. 15. Co mparison of seawater tempera tures in the Cordo va area during 1971.

55 I I I I I ,I {

� 0

C.J :.-. .u;::l 50 C1l H

45

�-e---G� Point Steele Beach

Ka talla Beach

Cordova Tide Station

4 �------�------�------.------�------�------�------� 10 20 30 10 20 30 9 June July Regression equations from Figs. 10, 11 and 12 indicate that at least 13 percent (.99 C. I.) of the clams at Point Steele Beach were actively spawning by June 23 when seawater temperatures rose abruptly from 47.50° F. to 50.75° F. Nevertheless, spawning in Orca Inlet did not commence until July 4 (at least 4 percent active spawning at .99 C.I.) when the seawater temperature rose from 46.5° F. on the 2nd to 50.0° F. on the 4th.

Spawning during 1971 in Cordova Sector 1 appeared to take place primarily within the months of July and August. The average seawater temperature during this 2-month interval ° was 49.3 1 ± 1.76 F. Overall spawning activities in Sector 1 during 1969 occurred between June 11 and September 30. The average seawater temperature during this period was ° 51.01 ± 1.99 F.

Further analysis of the apparent relationship between accumulation of temperature units and spawning activities was conducted using 1969 and 1971 data. For purposes of this analysis 32° F. was arbitrarily selected as a temperature base. Temperature units were considered to be the cumulative degrees (Fahrenheit) of the maximum daily deviation ° ± 32 F. that were observed from January 1 to the onset of spawning. In 1969, the period of accumulation was from January 1 to June 10. U.S. Coast and Geodetic Survey records contain only 101 of the 161 days of this period. However, by weighting the av erage deviation of the observed mean temperature by tho appropriate number of days in the month, the cumulative units were found to total 1085.85. Similarly, 1971 data for the entire month of February as well as two days in June gave an incomplete record but, by weighting the mean temperatures of January and March to approximate the February mean and by using these weighting procedures to cover the period January 1 to July 4, 1971, the cumulative temperature units were computed to total approximately 1198. If calculations were extended to July 24, when weight loss was very apparent, the result is 1507 temperature units.

A similar study was conducted on the American oyster, Crassostrea vzrgznzca, by Price and Maurer (1971) and its results showed potential value for this specie. Accumulation of temperature units, as determined by my procedure, appears to be a valid method for estimating the imminency of spawning by razor clams. It is assumed that the necessary minimum and maximum units for razor clams would be 1200 and 1500, respectively, with a possible average of 13 50.

I propose that once the required number of temperature units have accumulated (i.e., at least 1200), a seawater temperature of about 4 7 o F. (8.3 o C.) serves as the threshold spawning temperature. Spawning activity then increases as temperatures increase. I feel that hot, clear, calm days during the lower low tide cycles allow the low tide terrace to accumulate a tremendous amount of solar heat which, in turn, is rapidly converted into temperature units. The more rapidly these units are attained, the more profuse the spawning activity and the greater the probability of fertilization which, in turn, enhances the probability of heavy sets of young clams. Results of studies conducted by Nelson (1917), Orton (1920) and Loosanoff (1932) tend to support this conclusion.

A third study dealing with spawning was conducted during 1973 to relate spawning activity to observed changes in the hydrogen ion concentration (pH) of the gonad. Samples of clams (i.e., ff = 23 ± 11) were collected and analyzed for pH from May through September in Cordova Sectors 1 and 4 for this study. Each gonad was severed below the intestinal loop and various sensitivities of "pHydrion" papers (manufactured by Micro Essential laboratory, Brooklyn, New York) were touched to the exposed mass of gametes and associated tissues to determine their pH. Valve length and diameter of ova were measured and visual estimates of gonad ripeness recorded.

57 During mid-April, gonads (ovaries and spermaries) of Sector 1 razor clams averaged 25 percent or less in fullness and ova averaged 54.97 ± 11.08 microns in diameter. By early May, gonads of Sector 1 clams averaged about 70 percent fullness, ova averaged 105.63 ± 15.16 microns in diameter, and the pH of the gonads was slightly alkaline, measuring 7.90 ± 0.6855. Ripeness of gonads of Sector 4 razor clams during early May was slightly less than that observed in Sector 1 clams. Gonads of Sector 4 clams during this period averaged about 50 percent fullness, ova averaged 92.01 ± 12.14 microns in diameter, and theii pH was 8.04 ± 0.4880.

By late June, gonad fullness averaged nearly 100 percent for razor clams in Cordova Sectors 1 and 4; diameter of ova averaged 99.83 ± 12.08 microns for Sector 1 clams and 91.54 ± 9.21 microns for Sector 4 clams; and the pH of clam gonads from both sectors had plunged into the acid range (6.85 ± 0.1 734 for Sector 1 clams and 6.58 ± 0.1 280 for Sector 4 clams).

Subsequently, the pH levels of gonads from both sectors returned to the alkaline range. By late July, spawning was well underway in both sectors and by mid-August gonad fullness averaged less than 70 percent for Sector 1 clams and less than 35 percent for Sector 4 clams.

As the clams continued to spawn, gonad pH became more alkaline. Samples obtained in mid-September showed that gonad fullness in Sector 1 clams averaged 50 percent while gonads of Sector 4 clams averaged less than 25 percent. By late September, gonad fullness of Sector 1 clams averaged less than 30 percent.

Through analysis of variance, I was able to isolate five distinct levels of hydrogen ion concentration within the gonad of razor clams (Fig. 16) for the period under study. Table 7 provides the mean and standard deviation for each of these gonad pH levels.

The alkaline to acid stages were classified as the first through fifth levels of ripening. The fifth level of ripening was termed the threshold to spawning and thus is synonymous with the first level of spawning. The classification then reverses, going from acid to alkaline, becoming the first through fifth level of spawning. It is obvious from Fig. 16 that sampling did not occur at a time when obtainment of missing data points for Cordova Sectors 1 and 4 was possible. However, included data points clearly indicate the trends in both sectors and depict their unifonnity.

Seawater temperature measurements made in Sector 1 during 1973 revealed that 1200 temperature units had accumulated by June 15; 1350 units by June 26; and 1500 units by July 4. With reference to Fig. 16, it is evident that gonad pH of Sector 1 razor clams was probably in the third level of ripening on June 15; definitely in the fourth level of ripening on June 26; passed through the fifth level of ripening sometime between June 26 and July 11, and entered the second level of spawning.

Regression equations in Figs. 10, 11 and 12 indicate that on June 15, 92.12 ± 5.17 percent of the clams had not begun to spawn ; 0.99 ± 9.21 percent were actively spawning; and 0.00 ± 8.93 percent had completely spawned. For June 26 the equations indicate that 82.17 ± 5.17 percent had not begun to spawn; 6.58 ± 9.21 percent were actively spawning; and 2.18 ± 8.93 percent had completed spawning. Similarly, for July 4, regression data indicate that 72.64 ± 5.17 percent of the clams had not begun to spawn; 12.74 ± 9.21 percent were actively spawning; and 5.04 ± 8.93 percent had finished spawning.

Seawater temperatures for these dates were: June 15 - 45.4° F.; June 26 - 47.0° F. ;

58 8.4

8.2 A \ \ 8.0 5 \ 7.8 \ I 7.6 -o ro I c 0 2 I 4 CTl 7.4 C.J I _;:: +> I 7.2 [ 3 3 4- 0 / ] :r: Ji. ] VI D.. 7.0 \0 [ 2 4 \ 6.8 \ � ] 5 \ I 6.6 [ [ "!:{ ] l 6.4 () Cordova Sector 1

Cordova Sector 4 6.2 � re o1d -----�--r--- T�h � s h- - " tt 1 ' I I I rI �I I T ---r I I I I I � �� � l 0 20 30 9 19 29 9 19, 29 8 18 28 7 17 27 May June July Augu st September

Fig. 16. Five levels of hydrogen ion concentra tion (pH) in the gonad of razor clams fr om Cordova, Alaska, Sectors 1 and 4 and their relationship to the sequence of spawning. Table 7. Five levels of gonad pH in the razor clam, Cordova, Alaska, May to September 1973.

Standard Stage Mean pH Deviation

first level of ripening-pro-active 7.9 0.4909 fifth level of spawning-post-active

2 second level of ripening 7.4 0.2773 fourth level of spawning

3 third level of ripening 7.2 0.3230 third level of spawning

4 fourth level of ripening 7.0 0.3032 second level of spawning

5 fifth level of ripening 6.6 0.1281 SPAWNING THRESHOLD first level of spawning

60 and July 4 - 48.0° F. Little spawning activity was noted when the mid-July samples were collected, but spawning activity was apparent by late July. Thus, the first and second levels of spawning appear to be resting stages; the main spawning effort occurs in the third and fourth levels; and spawning terminates in the fifth level.

There was a pronounced fluctuation between mid-July and late August pH readings (Fig. 16). From mid to late July there was a change from acid to alkaline which corresponded to an increase in seawater temperature (from 48.2° F. on July 11 to 52.4° F. on July 27). Seawater temperature dropped to 49.0° F. on July 29 and rose slowly to 51.0° F. by August 10. As shown in Fig. 16, the lowering temperature appeared to be correlated With a lowering in gonad alkalinity. Then seawater temperature dropped to 50.2° F. by August 18, and rose again to 51.0° F. on August 27 with an associated rise in gonadal alkalinity. Seawater temperature dipped to 48.0° F. on September 1, rose to 51.6° F. by September 6, then gradually decreased to 47.0° F. on September 28.

Based on 1973 temperature gonadal pH correlations, the accumulation of 1350 to 1500 temperature units appears to be more appropriate than 1200 to 1350 units for predicting the spawning threshold of razor clams. Fig. 17 depicts monthly seawater temperatures obtained by the U.S. Coast and Geodetic Survey at the Cordova tide station from 1949 to 1973. From tho3o data I have prepared Table 8 which provides estimates of the probable range of spawning thresholds given a variety of temperature regimes.

Histological studies were conducted during 1973 and 1974 utilizing vertical and horizontal sections taken from the center of male and female razor clam gonads. All tissues were prepared using Delafield's hematoxylin stain and eosin Y counter stain. These studies were deemed necessary as a check on observations of living material in order to determine accurately the characteristics of the constituent cells of the gonads and manifest changes in gonad appearance with the passage of time. Results of gross inspection and histological studies of gonads were in agreement. Resource managers can use the temperature unit method in conjunction with gonad pH and regressions in Figs. 10, 11 and 12 as a guide to monitor spawning activity rather than relying solely on fixed dates for beach closures to protect brood stock. It is apparent that unseasonably warm weather prior to a fixed date closure may render active spawners vulnerable to capture.

Growth Rates

It is well documented that growth rates (age versus length) of razor clams vary with geographical location: Weymouth, McMillin, and Holmes (1925); Weymouth and McMillin (1931); Tegelberg (1961); and Bourne and Quayle (1970). The purpose of this section is to furnish recent data on growth patterns of razor clams in Alaska . for use in the management of these stocks and for surveillance purposes relative to the shellfish sanitation program.

Appendices 3a to 3ff provide data on the variety of growth patterns among various stocks in Alaska. Mr. Rae Baxter, Fishery Biologist, ADF&G, at Bethel, Alaska, has kindly furnished raw data on length and age from some growing areas that he visited during the late 1950's and early 1960's. The remaining data were collected by the author fr om 1969 to 1971.

In many instances the second annulus was extremely difficult, if not impossible, to read and, less often, the first annulus was undecipherable. Undoubtedly, there is a certain

61 LL 60 0

Q) S- :::5 +-' co 50

0\ N 9 9 9 9 ¢ 9 40 ¢ � 9 9 9 9 j! 9

r r T--- --.---· r- I I I ------. s... . s:: _Q S- >, Q) >, Ol. +-'. +-'. >. u co Q) co c_ co s:: :::5 0.. u 0 Q) r-::J LL � c::( :2 :::5 .--:::5 c::( Q) 0 z: Cl r-::J r-::J U")

Fig. 17. Means and standard deviation of seawa ter temperatures collected at the Co rdo va, Alaska, tide station fo r the period 1949 to 1973. Table 8. Estimated probable range of razor clam spawning threshold (accumulation of 1350 temperature units from January 1) in the Cordova, Alaska, growing areas.

Super warm Abnormally warm Nonnal Abnormally cold Super cold years years years years years

+30 +20 ± 1 0 -20 -30

0\ w April 18 May 6 May 27 August 16 September 29 to July 16 with

X = June 11

I ---- amount of error in aging very old specimens and attempts were made to minimize this type of error. Where annuli were unreadable the respective specimens were discarded. In most cases, identification of annuli was facilitated through the employment of a 3-diopter desk magnifier and high intensity lamp. However, for difficult specimens of great age, erosion of the periostracum with concentrated nitric acid was necessary to reveal the underlying annuli. The latter method is not recommended for rapid analyses because it is time consuming, but it is very accurate if the denuded shell is stained with Alizarin Red and subsequently rinsed with water. A more detailed description of this method is provided in the section dealing with discriminatory and sequential analysis.

As previously indicated, the majority of razor clams in Cordova Sector I are sexually mature and have attained legal size (1 02 mm or 4 inches) by their sixth full year of life. This age (measuring the sixth annulus of those clams having growth increment on this, the last annulus at the time of capture) was selected for comparing mean valve lengths of clams among various areas. This comparison for clams in the Cordova growing areas (by analysis of variance) is presented in Tables 9, 10, 11 and 12.

Although statistical tests show no significant difference in mean valve length of clams from four major bars in Sector I (Table 12), observations indicate that razor clams from Concrete Bar, also in Cordova Sector I, achieve a greater asymptotic length than the former. Concrete Bar clams were not compared with the former because they are too scarce to be used commercially. However, because of their seemingly greater maximum average length, the mean length of their sixth annuli were compared with those from Swikshak and Polly Creek beaches. These data are presented in Table 13. Analysis of variance reflected significant differences in the mean values. Results of the above data were the basis for discriminatory and sequential analysis discussed in a later section.

Data shown in Tables 14 and 15 relative to the I 0-90 percentile ranges of annuli reflect the overall differences in growth rates between Cordova Sectors I and 4. Of great significance, however, are the lengths and ages of the first order of recruit clams immediately (in a seasonal sense) prior to their threshold appearance into the legal fishery (Table 16). These data are extremely important, for they show that, although Tegelberg (1961) was, perhaps, justified in recommending a 4-inch (1 02 mm) size limit for Kanak Island clams based, in part, on attainment of sexual maturity, there was no biological justification for the subsequent reduction of the size limit to 4 inches in Cordova Sector I. This is illustrated by the fact that, with regard to the present size limit of 4 inches, Sector I pre-recruit clams prior to attaining this size have a mean age of 4.07 years which corresponds to a sexual maturity level of 77.84 percent. In other words, 22.16 percent of the razor clams that are recruited into the commercial fishery (or sports fishery) in Sector I are either sexually immature, or are just entering a stage of initial maturity.

As shown in a later section dealing with fecundity, female razor clams 4 inches (102 mm) in valve length contain considerably less ova than they would if allowed to attain greater size. Of fu rther interest, when comparing the 80 percent average lengths (in Tables 14 and 15) of clams from Cordova Sectors I and 4, it is seen that upon attainment of the sixth annulus, Sector I clams have an average length of 111.28 mm, which is equivalent to a sexual maturity level of 99.42 percent. Sector 4 clams, upon the attainment of the seventh annulus, have an average length of 110.34 mm and a probable sexual maturity level of I 00 percent. These average lengths, converted to inches, are 4.38 and 4.34, respectively. They are similar to the 4.50 inches advocated by Weymouth et al. in 1924. Since growth is slower and the asymptotic length and age are lower in Sector 4 than in the better producing bars of Sector I, I advocated an increase in the size limit to the former 4 1/2 inches to insure the integrity of spawning reservoirs in Sectors I and

64 Table 9. Analysis of variance of razor clam length (mm) at the sixth annulus ( 1963 cohort) from Strawberry Reef, Softuk Beach, Katana Beach and Kanak Island (outside beach).

Strawberry Softuk Katana Kanak Location Reef Beach Beach Island

Sample Means 98.7143 93.3333 93.2857 95.0833

Sample Totals 1382 280 653 2282

Sample Nu mber 14 3 7 24

Anal�sis of Variance

Source of Sums of Degrees of Variance Variation Squares Freedom Estimate

Between Samples 193.6977 3 64.5659

Within Samples 3398.7843 44 77.245 1

Total 3592.4820 47

64.5659 F = = < 77.245 1 .8358 2.82 F.95 Implies that the samples were drawn from sources whose average values did not differ from each other.

65 Table 10. Analysis of variance of razor clam length (mm) at the sixth annulus ( 1963 cohort) from Inside Ocean Bar, Southwest Ocean Bar, Strawberry Reef, and Kanak Island (outside beach).

Inside Southwest Strawberry Kanak Location Ocean Bar Ocean Bar Reef Island

Sample Means 107.8000 102.5897 98.7143 95.0833

Sample Totals 2156 4001 1382 2282

Sample Number 20 39 14 24

Analysis of Variance

Source of Sums of Degrees of Variance Variation Squares Freedom Estimate

Between Samples 1930.7356 3 643.5785

Within Samples 6797.3263 93 73.0895

Total 8728.0619 96

6 F = · 8.8053 > 4.00 F.99 . = Implies that samples were drawn from sources whose average values differed from each other. and : X Inside Ocean Bar versus X Southwest Ocean Bar

t(v 57) 2.2381 >2.0030 t.95 but

2.2381 <2.6660 t.99

66 Table 11. Analysis of variance of razor clam length (mm) at the sixth annulus ( 1963 cohort) from Inside Ocean Bar (lOB), Southwest Ocean Bar (SWOB), Erickson Bar (EB), Canoe Pass Trail Bar (CPTB), Little Mummy Island Bar (LMIB), and Rockslide Bar (RB).

Location lOB SWOB EB CPTB LMIB RB

Sample Means 107.8000 102.5897 118.7000 117.2222 121 .0833 117.5208

Sample Totals 2156 4001 2374 2110 1453 5641

Sample Number 20 39 20 18 12 48

C\ ---.} Analysis of Variance

Source of Sums of Degrees of Variance Variation Squares Freedom Estimate

Between Samples 7502.9411 5 1500.5882 Within Samples 11380.2963 151 75.3662

Total 18883.2374 156

_ 1500.5882 = F- -- �//� 19.9106 > 3.1394 F.99

Implies that the samples were drawn from sources whose average values differed from each other. Table 12. Analysis of variance of razor clam length (mm) at the sixth annulus ( 1963 cohort) from Erickson Bar, Little Mummy Island Bar, Canoe Pass Trail Bar and Rockslide Bar.

Erickson Little Mummy Canoe Pass Rocks! ide Location Bar Island Bar Trail Bar Bar

Sample Means 118.7000 117.2222 121.0833 117.5208

Sample Totals 2374 21 10 1453 5641

Sample Number 20 18 12 48

Analysis of Variance

Source of Sums of Degrees of Variance Variation Squares Freedom Estimate

Between Samples 143.7930 3 47.93 10

Within Samples 8424.2070 94 89.6 192

Total 8568. 0000 97

47.9310 F = 2. 706 F.95 89.6192 = .5348 <

Implies that samples were drawn from sources whose average values did not differ from each other.

68 Table 13. A comparison of the mean length at the sixth annulus utilizing razor clams from Concrete Bar, Cordova Sector 1; Polly Creek Beach, Cook Inlet; and Swikshak Beach, Alaska Peninsula.

Mean length of Sample Area sixth annulus Size

Polly Creek Beach 113.47 1 12

Concrete Bar 119.38 16

Swikshak Beach 128.79 33

Analysis of Variance

df Sums of Squares

Among means 2 6062.4549

Within groups 158 18807. 1 849

Total 160 24869.6398

6062.4549/2 F 25.4655 F.99(2, 158) 4.74 18807. 1849/158 = > =

69 Table 14. 1 Q-90 percentile range of razor clam annual ring lengths from plots 2, 3, 4, 5, 6, 7, 9, 10 JJ in Cordova Sector 1.]:/

Number of Annual Clams Ring Number plO p90 80%

812 3.84 10.04 6.94 ± 3. 10 802 2 17.08 34.51 25.79 ± 8. 71 779 3 32.68 63.62 48.15 ± 15.47 698 4 55.98 89.52 72.75 ± 16.77 611 5 80.46 114.14 97.30 ± 16.84 400 6 96.62 125.95 Ill. 28 ± 14.66 205 7 110.45 139.71 125.08 ± 14.63 161 8 124.29 145.67 134.98 ± 10.69 116 9 130.61 151.10 140.86 ± 10.24 49 10 135.20 154.32 144.76 ± 9.56 33 II 136.40 160.55 148.48 ± 12.08 19 12 138.20 159.80 149.00 ± 10.80 I I 13 141.80 158.40 150.10 ± 8.30 9 14 141 .20 159.80 150.50 ± 9.30 9 15 138.20 164.15 151.18 ± 12.98

Plot Little Mummy Island Bar J./ Plot 2 Erickson Bar 3 = Plot 4 Canoe Pass Trail Bar Plot 5 Shirttail Bar # 1 Plot 6 Southwest Ocean Bar Plot 7 = Inside Ocean Bar Plot 9 = Rockslide Bar Plot I 0 Northeast Concrete Bar Data collected by R. B. Nickerson, 2/ 1969.

70 Table 15. 1 (}-90 percentile range of razor clam annual ring lengths from Strawberry Reef, Softuk Beach, Katalla Beach, and Kanak Island in Cordova Sector 4. Jj

Number of Annual Clams Ring Number plO p90 80%

100 2.38 7.00 4.69 ± 2.31

100 2 13.21 33.50 23.36 ± 10.14

100 3 27.50 59.00 43.25 ± 15.75

200 4 44. 50 87.38 65.94 ± 21.44

200 5 64.93 104.36 84.64 ± 19.71

205 6 86.43 1 14.7 1 100.5"1 ± 14.14

214 7 97.97 122.70 110.34 ± 12.36

182 8 104.05 126.42 115.24 ± 11.19

145 9 110.67 132.67 121.67 ± 11.00

59 10 116.44 137.58 127.01 ± 10.57

21 11 120.60 140.85 130.72 ± 10.12

6 12 125.40 140.70 133.05 ± 7.65

3 13 130.40 143.60 137.00 ± 6.60

Data collected by R. B. Nickerson, 1969. j_/

7 1 Table 16. Composite analysis of the first order of recruit razor clams from Cordova Sectors 1 and 4 as applied to the present JJ legal size of 4 inches ( 102 mm) in valve length.

Mean Valve Standard Mean Standard Mean Standard Length Deviation Age Deviation Increment Deviation Sample Area mm mm Years Years mm mm Number

Katalla Beach 94.80 5.80 5.23 1.18 10.20 4.56 30 Kanak Island (Outside Beach) 94.30 4.49 4.73 0.88 11.00 3.98 30

Strawberry Reef (Outside Beach) 93.60 6.23 4.60 0.91 13.30 5.51 30

Softuk Beach 93.60 6. 19 5.20 0.90 13.40 5.35 30

Southwest Ocean Bar 92.89 5.06 4.35 0.60 12.69 4.12 52 -..] N Shirttail Bar #1 91.87 5.25 3.86 0.48 18.00 4.08 14

Inside Ocean Bar 90.44 5.80 4.31 0.66 17.09 5.16 43

Erickson Bar 90.11 7. 70 4.09 0.61 19.85 5.45 47

Little Mummy Island (Channel Beach) 87.34 9.66 3.97 0.68 23.76 6.63 87

Rockslide Bar 86.09 8.84 4. 15 0.71 22.49 6.55 113

Canoe Pass Trail Bar 80.71 12.22 3.87 0.68 28. 47 9.00 51

Northeast Concrete Bar 78. 79 13.41 3.60 0.48 31.97 9.26 29

11 The former legal size of 4 1/2 inches was reduced to 4 inches in 1962 as a result of Tegelberg's survey. 4. This was considered a biologically sound step toward wiser management of these stocks, especially in view of the renewed interest in large-scale commercial harvest of razor clams in the Cordova growing areas.

Tables 17 and 18 and Figs. 18 and 19 provide additional information relative to the legal or critical size of razor clams in Cordova Sectors 1 and 4. Although the first differential of absolute growth reaches a zenith at the third annulus for clams in both sectors, the first differential of absolute biomass peaks at the sixth annulus for Sector 1 clams and peaks at the seventh annulus for Sector 4 clams. These ages (subtract 1/2 year from the respective annulus to determine the age) agree favorably with our previous discussion of allowing the recruit population to achieve its greatest rate of growth in weight prior to capture which also encompasses the attainment of complete sexual maturity.

As evidenced by data in Table 17, the asymptotic length for Cordova Sector 1 clams is approximately 160 mm. This figure was derived from the 80 percent average lengths in this area which cover a spectrum of stocks and their individual unique growth patterns. The average span of time for this composite group of razor clams to attain 95 percent of their asymptotic length, as derived fr om Taylor's equation: 2.996 to A.95 = + --y- (Taylor, 1958) is 12.39 years. However, to reiterate, this figure takes into account clams that achieve great size and moderate age, moderate size and great age, and small size and low age. Taylor, using razor clam data of Weymouth and McMillin (1930) from Karl Bar near Cordova (there was no major bar of this name; it was undoubtedly a 'secret spot' of a person named Karl or Carl, probably located in the old Pot Hole area of Center Bar, known at this writing as Ocean Bar), calculated an asymptotic length of 176.6 mm and A.95 value of 15.17 years. The growth observed from the Karl Bar sample is similar to that observed from the present Concrete Bar and Big Point Bar clams, though sample sizes from the latter bars were not as large as those obtained by Weymouth and McMillin.

The largest whole razor clam I have observed was captured at Big Point Bar by a commercial digger on February 11, 1971. Total valve length of this clam was 175 mm ; total drained weight was 410.65 g; and the specimen revealed 11 annuli on each valve. Therefore, the asymptotic length of some stocks in Cordova Sector 1 and the corresponding A.95 value would be much greater than those observed in the general treatment given here.

The asymptotic length of Cordova Sector 4 clams (Table 18), also obtained from 80 percent average lengths, is 145 mm and the A.95 value is equal to 14.07 years. Values obtained ) for Sector 4 clams probably reflect a truer representation than those obtained for the Sector 1 clams due to the greater variability of habitat type in the latter. The oldest specimens observed from Sectors 1 and 4 were 18 and 12 years, respectively. In summary, due to the composite nature of the data, calculations based on slopes derived fr om the von Bertalanffy growth equations (Ricker, 1958) and from Taylor's equation (Taylor, 1958) ) indicate a maximum average life span for razor clams in Sector 1 of 12.39 years, whereas in Sector 4 a maximum average age of 14.07 years is evidenced.

Polly Creek razor clams exhibit an overall growth rate slightly less than that observed for Cordova Sector 1 clams, although the peaks of the regressions of the first differentials of absolute growth and biomass also correspond to the third and sixth annulus, respectively (Table 19; Fig. 20). From these data the 4 1/2 inch size limit in effect at Polly Creek Beach corresponds almost exactly with the critical size observed. It should be emphasized,

73 ) Table 17. Eighty percent average length of razor clams from Cordova Sector 1 and data for fitting a Walford line to length.

= Using final trial £ "" 160 Adjusted Age No. of Age (years) Clams Weight Length £ oo-£ t log e (£ oo-£t) (years)

t g mm mm t -t0 0.5 812 -- 6.94 -- -- 0.80 1.5 802 -- 25.79 -- -- 1.80 2.5 779 6.58 48. 15 - -- 2.80 3.5 698 25.14 72.75 -- - 3.80 4.5 611 64.62 97.30 - -- 4.80 5.5 400 99.89 111.28 48.72 3.89 5.80 6.5 205 145.60 125.08 34.92 3.55 6.80 7.5 161 186.50 134.98 25.02 3.22 7.80 -....) +:>- 8. 5 116 214.20 140.86 19. 14 2.95 8.80 9.5 49 234.40 144.76 15.24 2.72 9.80 10.5 33 254.40 148.48 11.52 2.45 10.80 11.5 19 257.60 149.00 11.00 -- 11.80 12.5 11 263.80 150.10 9.90 - 12.80

k = 0.75578

K = 0.28

Y-axis intercept = 5.54886 5.54886 - 5.07517 = = 1.69 to 0.28

£t = 160(1 - e ··0.28(t-1.69))

Q, t + 1 = 39.0752 + 0.75578 £t Table 18. Eighty percent average length of razor clams from Cordova Sector 4 and data for fitting a Walford line to length.

= Using final trial Q,� 145 Adjusted Age No. of Age (years) Clams Weight Length � -Q,t log e(£ �- £t) (years)

t g mm mm t - t0

0. 5 100 -- 4.69 - - 0.46 1.5 100 -- 23.36 - -- 1.46 2.5 100 3.94 43.25 - -- 2.46 3.5 200 14.94 65.94 - -- 3.46 4.5 200 32.07 84.64 63.36 4.15 4.46 5.5 205 56.56 I 00.57 47.43 3.86 5.46 6.5 214 75.63 110.34 37.66 3.63 6.46 7.5 182 86.84 115.24 32.76 3.49 7.46 -J V1 8. 5 145 103.10 121.67 26.33 3.27 8.46 9.5 59 118.00 127.01 20.99 3.04 9.46 10.5 21 129.20 130.72 17.28 2.85 10.46 11.5 6 136.70 133.05 14.95 - 11.46 12.5 3 149.90 137.00 11.00 - 12.46

k = 0.79453

K = 0.23

Y-axis intercept = 5.22

5.22 - 4.98 t = = 1.04 o 0.23

Q,t = 145 (1 _ e -0.23(t-1.04))

Q,t + 1 = 29.79 + 0. 79453 Q,t AGE 5 10 15 I 6

B 5 k A. Walford graph for length of razo r clams wh ere k, ,...--.. the slope = 0.755 and r = 1-k = the ratio of .w all deaths to population in time t. r-i 4 I 8 B. Final trial value of loo = 160 m. r-i ...... , Q) 3 C. Firs t differential of ab solute growth . 0.0 r-i0 D. Firs t differential of ab solute biomass . 2

200 50 - I A c

_logY= 0.80207 + 2.59696 (log X) - 2.71492( log x2 ) 99 .42% Sexually Ma ture ,...--.. I .._., -.J 150 § 25 0\ ,.c:: I Change in .w !=!0.0 iyx = Q) 0.9774 ....:1 I I �I'\

r-i Mature + lOO_J I I I I I .w ok:' ���---:-:� Q) 0.0 D t1l ,...--.. .w 2 t1l ...... ,0.0 log y�-3 . 76332 + 13.67 213(1og X)- 8.65159 (1og x ) ,...--.. 50 .w 50 I ,.c:: '-'§ 0.0 -ri ..... ,.c:: Q) iyx = 0.9281 .w :::;: 0.0 I / � .... !=! Q) ....:1 0 0 I I 1_.-- I I I I I I I I I 2 3 4 6 8 10 11 ¥ � 0 50 100 150 200 f0 1 5 7 9 12 13 14 Length (mm) at age t Annual Rings

Fig. 18. Growth of razor clams fr om Cordo va Sector 1. AGE 5 10 15 6 B

5 A. Walford graph for length of razor clams where /""', k, .w .-I the slope = 0.794 and r = 1-k = the ratio of all deaths to population in time t. 4 8 00 .-I B. Final trial value 1 = 145mm. '-../ I -� Q) 3 bO0 C. Firs t differential of ab solute growth . .-I ' D. Firs t differential of absolute biomass. 2

200 so c A 1

__....._ log y = 0.68683 2.27979(log X)-2 .2S 366 (log x2 ) '-../!§ + lS O ...c: 2S I -.) .w -.) i bO Change in Biomas � Q) .-I r-:1 + I iyx = 0.8634 .w I / � Q) 100 bO(\j 1 o I I I I I I I I r1 I I ,...... , .w (\j // I I I D /""', I // I __....._ § '-"bO .w ...c: .w 50 ib bO ·ri so � log Y = -2 . 46S20 9.11393(log X) -S . S 3086 ( log x2 ) Q) Q) + r-:1 :3 16/ = 0.8946 I iyx 0 0 r--T 11 12 14 0 so 100 lSO 200 0 1 2 3 4 s 6 7 8 9 10 13 Length (mm) at age t Annual Rings

Fig. 19. Growth of razor clams fr om Cordova Sector 4. Table 19. Standard mean length of razor clams from Polly Creek, west side of Cook Inlet, and data for fitting a Walford line to length.

U sin� final trial 9-""= 155 Adjusted Age No. of Age (years) Clams Weight* Length 9-""-9- t log e(9- ""- 9-t) (years)

t g mm mm t - t0

0. 5 115 - 6.20 - -- 0.83 1.5 115 - 25.74 - - 1.83 2.5 115 9.10 53.20 - - 2.83 3.5 115 34.08 79.89 - -- 3.83 4.5 115 71.04 100.24 54.76 4.00 4.83 5.5 112 106.20 113.43 41.57 3.73 5.83

--...) 6.5 104 131.10 121.04 33.96 3.53 6.83 00 7.5 99 160.20 128.74 26.26 3.27 7.83 8.5 93 186.10 134.82 20.18 3.01 8.83 9.5 58 200.40 137.95 17.05 2.83 9.83 10.5 32 223.40 142.62 12.38 2.52 10.83

k = 0.78663

K = 0.24

Y-axis intercept = 5.20

5.20 - 5.04 t = = O.E7 o 0.24 -0.24(t-0.67) H = 155 (1 _ e )

u + 1 = 33.07235 + 0. 78663 9- t

*Using regression for Cordova Sector 1 razor clams July 5, 1971. u u u u AGE

10 �5 6

B 5 /"""'. A. Wa�ford graph for length of razor clams where .j...J k, the slope 0. 786 and r = 1 = the ra tio of r-l = - k al� deaths to population in time t. 4 8 r-l '--" B. Final trial value of loo = 155mm . Q) I � bD 3 0 C. Fi�s t differential of absolute growth . r-l 1 � D. Fi�s t differential of ab solute biomass .

2 » 50

A c

J /"""'. / I 2 log v = 0.80396 + 2.54027(log X) -2 . 70 784(log x ) '--"� 0 -.l 150--J ..c 25 \0 .j...J bD � Change in Biomas Q) ...:1 I r-l I iyx = 0.9518 \ I I "

/"""'. // I r /"""'. bD '--"§ '---' + 2 ..c 50 .j...J log "': = -2 . 70304 11. 23223(log X) -7. 37069 (log x ) .j...J ..c s o -l bD bD � "M Q) Q) v H ::;:: iyx = 0. 7946 0

0 L 0 I I I I I 2 5 6 7 10I I i2 1r·14 0 50 100 150 200 I0 1 3 4 8 g 11 Length (mm) at age t Annual Rings

Fig. 20. Growth of razor clams from PJ!ly Creek Beach. however, that body weights of Polly Creek clams were derived from length-weight regressions obtained from Cordova Sector 1 clams. At any rate, the asymptotic length of Polly Creek clams (from the samples obtained) is 155 mm and the A.95 value is 13.15 years. In the two samples of Polly Creek clams examined the largest was 166 mm and the oldest was 17 years.

Razor clams from Swikshak Beach were the largest examined. As evidenced with Cordova Sector 1 and Polly Creek clams, the first differentials of absolute growth and biomass assume a peak at the third and sixth annulus, respectively (Table 20; Fig. 21 ). Again, body weights were derived from Cordova Sector 1 regressions. The critical size at the sixth annulus for Swikshak clams exceeds the present 4 1/2 inch size limit designated for this district by almost 15 mm. The sample of clams obtained from the Swikshak area was not very large and may not have been representative of the general growth rate there. If, however, it is fairly representative, a 5-inch size limit would be more in keeping with the observed critical size. The asymptotic length of Swikshak clams (from the sample obtained) is 165 mm and the A.95 value is 10.51 years. In the sample of Swikshak clams the largest was 167 mm and the oldest was 13 years.

It must be reemphasized at this point that the largest clams do not, as a rule, correspond tn th P oldf'st rl:lms. 1\s statf'd f'arlif'r, th f' largf'st nt70r dam obsenred by the author was 175 mm in valve length and was entering its eleventh year of life. Conversely, three 18-year-old clams were captured by a commercial digger on three separate occasions during 1969, from a bar in Cordova Sector 1, that measured 135 mm, 138 mm, and 144 mm, respectively. In regard to Polly Creek clams, two clams measuring 166 mm were 11 and 12 years old, respectively, whereas the oldest at 17 years measured 140 mm. Similarly, though not as apparent, the largest clam in the Swikshak sample at 167 mm was 12 years ol.d, and the oldest at i3 years measured 152 mm in length. Age-Length-Weight Relationships

These relationships, because they supply rapid estimates of biomass and year-class strength for individual stocks throug..h the input of one of the three related variables, are of particular value to management personnel. Length-weight relationships were obtained from representative samples of razor clams collected at Cordova Sectors 1 and 4 during 1971. Six sets of Sector 1 samples were procured from April to October and five sets of Sector 4 samples were collected during the period April to August. These clams were rinsed of sand at the laboratory, allowed to drain for 10 minutes, then weighed to the nearest 0.001 g with an OHAUS CENT-0-GRAM scale having a capacity of 311 g. After weighing, the valve length was obtained to the nearest millimeter, using a MITUTOYO verniercaliper. The clams were then shucked and their valves cleaned and numbered to correspond with the respective weight and length at that particular time period. Each set of numbered valves was packaged, labeled, dried, then stored for subsequent aging.

Aging of the valves was done in the manner previously described (on page 64 ). Multiple regressions were calculated using the age, length and weight data of August from Cordova Sector 4 and the October data from Sector 1. These time periods were chosen as they coincided closely with the conclusion of the spawning period for each sector and were presumed to indicate the approximate weights at each respective length and age that could be expected upon the resumption of the commercial fishery early the following year.

Length-weight relationships by time period for razor clams from both sectors are listed in Tables 21 and 22, and are further illustrated in Figs. 22 and 23. From commercial razor clam diggers' daily log sheets, in which records of live weight and the resultant

80 Table 20. Standard mean length of razor clams from Swikshak Beach, Alaska Peninsula, and data for fitting a Walford line to length.

Using final trial Q, oo= 165 Adjusted Age No. of Age (years) Clams Weight* Length Q, oo_ Q,t log e(Q, =-Q,t) (years)

t g mm mm t - to 0.5 48 -- 6.44 0.2 1.5 48 - 27.31 1.2 2.5 48 12.80 59.08 2.2 3.5 48 60.45 95.33 69.67 4.24 3.2 4.5 46 117.30 116.89 48.11 3.87 4.2 5.5 37 161.70 129.09 35.91 3.58 5.2 6.5 22 205.60 139.04 25.96 3.26 6.2 00 ...... 7.5 17 245.10 146.71 18.29 2.91 7.2 8.5 11 271.90 151.54 13.46 2.60 8.2

k = 0.722535 K = 0.325

Y-axis intercept = 5.527 14

5.527 14 - 5.10595 t = = 1.296 o 0.325

.Q.t = 165 (1 _ e -0.325(t-1.296))

H + 1 = 45.78 17 + 0. 7225 .Q.t

*Using regression for Cordova Sector 1 razor clams, July 5 and 6, 1971. AGE 5 10 15 6 B

5 A. Walford graph for length of razor clams where k, thE slope = 0.722 and r = 1-k = the ratio of """".j.J r-i all deaths to population in time t. I 4 8 B. Fir:al trial value of leo = 16Smm . r-i '-'Q) C. Firs t differential of ab solute grow th . 00 3 0 -1 � r-i ' D. Firs t differential of ab solute biomass . 2

c 200 so A / • log y=0. 776: 1 + 3.16S83 (log X) - 3 .42924(log x2) """" Ch ange in Biomas / '-'§ I ,..c:: 00 1S0 \ .j.J 25 iyx = 0.9786 N I 00 -1 I ""' 1 a Q) r-i I ./ I I ....::1

+ .j.J

Q) 00 100 0 Cll T"""""'-r .j.J D (1j + 2 """" log Y = -4. 02069 1S.S99S8(log X)-10 . 44444(log x ) """"00 '-'§ ,..c:: '-' .j.J .j.J iyx = 0.9318 ,..c:: 00 00 r:: so so -1 ,.. - / " Q) ·ri ....::1 Q) :::;:

0 �------�------�------�------�o 0 50 100 150 200 0T I1 2(I 3 4I 5 I I6 7 I 8 I 9 I 10 I 11 I 12I. 13,...... , 14 Length (mm) at age t Annual Rings

Growth of razor clams fr om Swikshak Beach. Fig. 21. Table 21. Length-weight relationship of razor clams in Cordova Sector 1 collected during 1971*.

Weight (grams)** Length April June July July August October (mm) 21-24 5-12 5-6 21-24 10-12 5

10 0.01 0.02 0.03 0.04 0.05 0.07

20 0.32 0.36 0.38 0.39 0.41 0.45

30 0.53 1.09 1.41 1.61 1.84 2.49

40 1.77 2.94 3.61 4.03 4.52 5.88

50 4.42 6.34 7.44 8.13 8.93 11.17

60 11.87 10.39 13.46 11.33 10.91 12.58

70 18.98 17.54 22. 19 19.04 18.43 20.49

80 28.49 27.64 34.23 29.86 29.00 31.27

90 40.76 41.26 50. 14 44. 37 43.25 45.42

100 56.19 59.09 70.62 63.30 61.89 63.45

110 75.11 81.74 96.20 87.24 85.55 85.80

120 97.88 110.00 127.70 116.90 115 .00 113.10

130 124.80 144.30 165.40 153.10 150.80 145.60

140 156.40 185.80 210.40 196.40 194.00 184.20

150 193.10 235.00 263.20 247.90 245.30 229.30

160 234.90 292.60 324.50 308.00 305.40 281.20

170 282.40 359.60 395.00 377.70 375.10 339.80

n = 11 60 26 26 30 34 r value*** .9925 .9956 .9967 .9958 .9908 .9919

* Derived from log Y = a + b log X. ** Note that weights of razor clams of the size classes 10 to 50 mm were derived separately from larger clams and are based on small sample sizes. *** Coefficient of correlation as related to clams larger than 50 mm.

83 Table 22. Length-weight relationship of razor clams in Cordova Sector 4 collected during 1 971 *.

Weight (grams)

Length April May June July August (mm) 21-26 15 19 11 7

60 9.17 11.09 9.98 11.45 11.15

70 15.35 18.03 16.42 18.10 19.00

80 24.00 27.48 25.28 26.95 28.39

90 35.57 39.82 36.98 38.23 41.61

100 50.62 55.54 51.99 52.34 58.60

110 69.63 75.01 70.74 69.50 79.87

120 93.17 98.74 93.74 90.05 105.90

130 121.70 127.10 121.30 114.20 137.40

140 156.00 160.50 154.20 142.40 174.80

150 196.50 199.60 192.80 174.90 218.80

n = 14 19 29 45 27 r value .9716 .9885 .9782 .7188 .9521

*Derived from Log Y = a + b log X.

84 Fig. 22. Age-length-weigh t relationship of razor clams collected fr om Ca noe Pass Trail Bar, Cordo va Sector 1, October 5, 1971.

AGE 6 3 4 s 7 8 11

Log X1 -4.8388 -0. 0362 log X2 + 3.3 171 log X 3

il. 2 3 0.990S

200

lSO ,-.. bO '--"

.w .c bO ·r-l QJ � 100

so

150 so 100 Length (mm)

85 Fig. 23. Age-length-weigh t relationship of razor clams collected fr om Co rdol'a Sector 4, August 7, 19 71.

AGE (years) 4 s 6 7 89

Log X1 -4. 7116 - 0.0730 log X2 + 3.2819 log X3

il. 23 0.9521

200

1S O """"'- 00 '-./ w ..c 00 ·r1

so

so 100 150 Length (mm)

86 edible weights were tabulated for Cordova Sector 1 clams, an average edible yield of 39.4 percent was calculated. This percentage was held constant and applied to the regression results obtained from the April and early July length-weight samples. This procedure yielded information in Fig. 24, which compares usable weight to total weight at specific lengths during the early seasonal growth period and again just prior to spawning.

Population Dynamics and Habitat Relationships

Frequency of Occurrence by Tide Level

A major objective toward formulating reasonably accurate censusing methods was to determine if razor clams were stratified by tide level on the low tide terrace. Other workers have hinted of higher and/or lower clam densities, or what constituted upper limits of the clam bed (Hirschhorn, 1962; Tegelberg, 1964; and Bourne, 1969), but until now, no one has defined thest ructural profile of razor clam stocks as relates to frequency stratification by tide level. Data obtained from this study have a critical bearing on a new method of razor clam population estimation which will be discussed later under the section entitled Survey Techniques.

Following removal of all observed razor clams from Cordova Sector 1 study plots by digging (see Razor Oam Life History Studies, page 37), 10 percent of the substrate in each plot, to a depth of 1 foot (0.3048 m), was washed through a fine-mesh screen. This was accomplished by means of a 5 sq. ft. (0.4645 m2) sampling frame constructed from 1 /2-inch (1.27 em) reinforcement rods welded together, each side measuring 2.236 feet (0.68 m). This frame had a 6-inch (15.24 em) stud at each comer projecting downward to anchor it in place. Handles were welded to the upper surface of two opposing sides (Plate 5). A 'No. 2' long-handled shovel was used to excavate the substrate within the sampling frame, the blade of the shovel being 1 foot (0.3048 m) in depth. Thus, each sample yielded 5 cu. ft. (0.1415 m3) of substrate.

Twenty samples were taken at random in each plot. The excavated substrate comprising each sample was placed into a portable screen fashioned in the form of a wheelbarrow (Plate 6). This consisted of fine copper screen having 16 meshes to the inch (2.54 em) overlaying a heavy-duty galvanized 1/2-inch (1.27 em) mesh screen; both were riveted to the bottom of an 8-inch (20.32 em) deep plywood box that could easily be lifted from the wheelbarrow frame for cleaning. Substrate was washed through the bottom of this screen by means of a continuous stream of water supplied by a Homelite Model XL pump that was situated in a skiff (Plate 7). The complete sampling scene is shown in Plate 8. Examples of razor clams obtained from screening are shown in Plates 9 and 10.

The objective, after screening, was to combine the dug and screened subestimates into a total estimate. The method employed is described in Appendix 4.

During spring and summer 1971, a similar study was conducted at Point Steele Beach on the southeast coast of Hinchinbrook Island, approximately 4 miles (6.44 km) west of Orca Inlet. This razor clam growing area possesses the classical configuration of a razor clam beach due to the heavy surf, strong tidal currents, long-shore bars and long-shore troughs (Figs. 25 and 26). As a habitat type this area is very much different from the offshore bars of Orca Inlet. Interestingly enough, a description of Point Steele Beach is strikingly similar to that of North Beach, Graham Island, Queen Charlotte Group, B. C., as given by C. McLean Frazer in 1928. Dr. Frazer stated (Frazer 1930:14 1-142): "The

87 A comparison of usable weigh t to total weight fo r razor clams collected fr om Cordova Fig. 24. Sector 1, 1971.

8 8 0 r­ July (just prior to spawning) rl

0 N� 0 rl rl§ rl n 0 0§ rl

bO

� ..c: �- bD ·rl Q) :s: 20 Q) rl ..0 eel rJ) Ap ril !=J 0 00§ rl 15 0 r­� rl

0 \0§ rl 0 LJ")� 10 rl 0 -.:t§ rl 0 C'j§ rl 0 N§ 0 rl rl§ rl 50

100 150 200 250 300 350 400 Total He igh t (g) 88 Plate 5. Square sampling frame delineating an area of 5 sq. ft. (0.46 m2). The number 2 long-handled shovel shown within th e fr ame has a blade 1 fo ot ( 0. 3048 m) in length fo r conveniently excavating to that depth.

89 Pla te 6_ Sampling screen mounted on a wheelbarro w-type frame fo r washing substra te thro ugh to obtain young clams_ The screen is lifted out fo r removal of debris.

90 Pla te . O ted in skiff /(Jr ease in washing substrate 7. Small fJ rtab!e Ho me lite fJII/JlfJ moun through t!ze samuling screen.

91 Pla te 8. Co mplete view of th e screening operation at Rocks/ide Bar, Orca Inlet, ll'ith a portion of the southwest shore of' Hawkins Island in the backgro und.

92 Pla te 9. Razor clams collected by screening metlz od showing approximate range of cap turable size:

93 Pla te 10. Variations in size of 1-year-old razor clams collected by the screening method. Nu merals of the lo wer scale are in centimeters.

94 COAST

BACKSHORE FORESHORE

BREA.KER ZONE

�

BEACH SCARPS LOl-l TIDE

\!) Vl TERRACE

Fig. 25. Divisions of a ty pical beach. SLOPE OF FORESHORE :

1. Coarse sand beaches = As much as 10° to 15 °

2. Fine sand beaches = Usually 1° to 3°

FORESHORE

HIGH TIDE --- )))

\0 UP RUSH 0\ � COARS E MATERIALS

BACKWASH FINE MATERIALS (( ( } -- ...... LOW TIDE LOW TIDE TERRACE RIP CURRENTS \\_ Fig. 26. Basic structure of fo reshore. whole beach is directly exposed to the full force of the waves as they come from the open Pacific... As the beach is crescent shaped with the concavity of the crescent facing the wind, the effect of the heavy seas becomes much concentrated. . .. The slope of the beach is considerable, and in consequence, the intertidal area is seldom wider than 500 yards, even during the July spring tides. The 3-fathom mark is never more than 1 1/2 miles out and may be less.... The 5-fathom limit varies from 2 miles to 1/2 mile; the 10-fathom from 5 miles to 2 miles; the 20-fathom from 8 miles to 3 miles. The slope is such as to produce a heavy surf during a storm. The sand shifts very materially and during the spring tides, in many places large pools are left above low tide, when the tide is out, some of which have outlets forming runnels with quite strong currents. Above, at and near high tide, the sand is usually soft and yielding, but lower than this, when the tide is out, it becomes hard and smooth, except when it is intercepted by runnels."

The purpose of the Point Steele Beach investigation was to compare the frequency of occurrence of clams by tide level between this beach and that at Orca Inlet.

Tide levels were determined in the manner previously described for the Orca Inlet study plots, but probably were not as precise due to the uprush of the surf. Because of the heavy surf and breaker action encountered at Point Steele Beach (Plate 11), the -3 fo ot (-0.91 m) tide level could not he estahlish eci , for th e npmsh w::� sh erl over th i<: level ::�t extreme minus tides, although the upper tide levels became exposed.

Two series of study plots were established from approximately the -2 to the +5 foot (-0.61 to +1.52 m) tide level (Plates I 2 and 13). These were termed the A and B series. Due to the time and distance involved in reaching the site, each plot was made one-fourth of the size of the Orca Inlet plots, that is 5 by 50 feet (1.52 by 15.24 m). The fu tility of following the same procedure that had been used for the Orca Inlet study plots (i.e., repeated digging to remove the bulk of the clams followed by screening) was recognized early in the sampling because of the great number of small (<40 mm: 1- and 2-year-old) clams present. Therefore, since all plots in series 'A' and 'B' had been disturbed by digging, a third series of plots was established and termed 'C'. The 'C' plots (Appendix 2j ) were sampled solely by screening (Plates 14 and 15), except to remove large clams within the sampling frame before they could escape to deeper levels.

The great distances between some of the tide levels (Plate 16) and the necessity to use buckets to carry water for washing substrates through the screen (the use of the pump was preclusive due to surf and breakers and maneuvering the loaded wheelbarrow was too unwieldy) resulted in restricted sample sizes. It is felt the eight subsamples, providing 40 cu. ft. ( 1.13 m3) per plot which were collected under these circumstances would be representative of clam populations on this beach. Since each plot contained 250 cu. ft. (7.08 m3), the subsamples represented 16 percent of each plot. Unfavorable weather conditions prevented collection of the planned number of subsamples at the -2 foot tide level, however, six samples were obtained at that level and three samples were taken at the -1 1/2 foot (-0.46 m) tide level for evidence of transition of frequencies.

Following the Point Steele Beach sampling, minor studies were conducted at Katana and Softuk beaches, Cordova Sector 4 (Fig. 4, page 23), for the purpose of providing additional insight into the Orca Inlet and Point Steele investigations. Katana and Softuk beaches (Plates 17 and 18) are coastal breaker beaches somewhat protected from the prevailing southeast winds by Kanak Island and the Martin Islands, respectively. Tide levels were established as previously described. They ranged from the -2 to +3 feet (-0.61 to +0.91 m) relative to mean lower low water. For various reasons only three samples (taken in the same manner as at Point Steele Beach) per tide level per beach per tide could be collected.

97 Pla te 11. Surf at Point Steele Beach study site, located on the east coast of Hinchinbrook Island. Co mpare with Pla te 1.

98 Pla te 12. Study plot at Po in t Steele Beach site measured 5 by 50 fe et 0. 52 by 15. 24 m) with the lo ng axis parallel to the water line, i. e. , tide level.

99 Plate 13. Study plot at the Poin t Steele Beach site becoming exposed on th e ebb.

100 Pla te 14. To te-Cote 's were used to transport equipment fr om Boswell Bay to the Po int Steele Beach study site. Screening apparatus is lashed to this machine. Rip channel is in the immediate background with breakers in the distance.

101 Pla te 15. One- and two-year-old razor clams recovered by screening at the Poin t Steele Beach study site. As shown, th e fi ne, 16 mesh per inch (2. 54 em) copper screen is backed by 1/2-inch 0. 27 em) mesh galvanized screen.

102 Pla te 16. Distances between tide levels at the Poin t Steele Beach study sites were great compared to the Orca Inlet sites. To te-Gate 's portray the distance between mean lower lo w water (foreground) and the +1 fo ot (+0. 30 m) tide level.

103 Plate 17. Aerial view of Ka talla Beach, Cordova Sector 4, lo oking northwest.

104 Pla te 18. Aerial view of Softuk Beach, Cordova Sector 4. with the Copper River Delta in the background.

105 Since these beaches are in juxtaposition and have similar habitat characteristics and the sample sizes were small, results were pooled for purposes of analysis and correlation with the Orca Inlet and Point Steele studies.

Repetitive digging in the Orca Inlet study plots provided an estimate of the density of mainly large razor clams (580 mm) and revealed the manner in which they were stratified by tide level (Tables 23 and 24). The observed abundance of razor clams at the -2 and -3 foot (-0.61 and -0.91 m) tide levels was probably low because of the lesser frequency of minus tides suitable for examining plots in this tide range and the poorly drained substrate which allowed many clams to evade capture. Screening yielded an unknown proportion of the residual population comprised mainly of 1- and 2-year-old clams, and the density of screened clams was low, i.e., X = 0.01 clams per cubic foot (0.0283 m3) for the 1800 cu. ft. (50.94 m3) of substrate that was screened. Stormy weather, higher low tide heights and the passing season prevented screening of remaining plots, so utilization of the method for combining subsamples (Appendix 4) could not be meaningfully employed. Therefore, only the empirical data from dug clams will be considered here.

Tables 23 and 24 illustrate that in most instances frequency distribution of these larger razor clams by tide level was generally in the form of a quadratic curve with the mode noar tho zoro tido lovol. Sito t1 clam di[Jtribution data did not confom1 to thin particular form of curvilinearity because of the steepness of the site and its poor drainage characteristics. This resulted in puddling at the zero tide level and slumping at the -1 and -2 foot (-0.30 and -0.61 m) tide levels, causing poor capture conditions. Also, high clay content at lower tide levels probably reduced density and survival; this, however, will be discussed in detail in a later section.

Site 4 was the only sampling area that was screened from the +3 to the -1 foot (+0.91 to -0.30 m) tide level. This procedure altered the general shape of the distribution in such a manner that the mode shifted to the zero tide level. That is, the estimate of the total number of clams at the +3 foot (+0.91 m) tide level became 55, and the estimate at the zero tide level became 61.

Empirical data in Table 23 indicate that the trend of razor clam frequency of occurrence by tide level increased from a low at the +4 foot ( + 1.22 m) tide level to a high point in the vicinity of the zero tide level; the trend then decreased to the lowest tide levels sampled. These data were tested by dividing them into two groups; the +4 to +1 foot (+1.22 to +0.30 m) tide level which included all eight sites, and the zero to -3 foot (-0.91 m) tide level for Sites 2, 3, 4, 7 and 9. The original variables were transformed by an arcsin square root transformation then subjected to analysis of covariance (Tables 25 and 26). Based on these analyses it was concluded that no real differences existed among the adjusted and unadjusted treatment means and one regression line could be used for all observations, therefore, pooling of the Orca Inlet samples for comparison with data from Point Steele Beach and Sector 4 was warranted.

Sampling within the series 'C' study plots at the Point Steele Beach site revealed a very similar distribution profile as that for the Orca Inlet study plots, except that yield at Point Steele was proportionately greater at the +4 and -2 foot ( + 1.22 and -0.61 m) tide levels. Because of the obvious abundance of small (young) clams at the Point Steele site, a proportionate increase at the -2 foot (-0.6 1 m) tide level was expected, but the finding of clams at the +4 foot ( + 1.22 m) tide level came as a surprise. Theonly plausible explanations for the occurrence of clams at the +4 foot tide level at Point Steele were : (1) the tide level determinations at Point Steele were about 1/2 foot (0.15 m) in elevation above the actual levels; or (2) the tide levels were very close, but due to low clam densities

106 Table 23. Distribution of dug razor clams by plot per tide level ± mean lower low water from eight study sites in Sector 1, Cordova, Alaska, 1969.

Number of clams 2er __12_lot by site Tide level Site number ft. m. 2 3 4 5 6 7 9 10 Total

+5 +1.52 0 0 0 0 0 0 0 0 0

+4 +1.22 0 0 0 0 0 0 0 0 0

+3 +0.91 3 2 25 0 1 0 1 7 39

+2 +0.61 18 16 18 3 13 8 24 5 105

+1 +0.30 31 21 19 5 68 15 13 8 180

...... 0 0 23 13 21 14 69 22 30 12 204 0 --.) -1 -0.30 21 5 6 8 55 18 37 5 155

-2 -0.61 22 2 6 4 too 11 31 1 77 wet

-3 -0.91 9 2 3 too -- I 20 too 35 wet wet

Total 127 61 98 34 206 75 156 38 795

Identification of site number: 2 Little Mummy Island Bar 3 Erickson Bar 4 Canoe Pass Trail Bar 5 Shirttail Bar 6 Southwest Ocean Bar 7 Inside Ocean Bar 9 Rockslide Bar 10 - Northeast Concrete Bar Table 24. Distribution of dug razor clams by age per tide level ±mean lower low water from eight study sites (data lumped) in Sector 1, Cordova, Alaska, 1969.

Number of clams in their nth fu ll year of life

Tide level Age ft. m. 1 2 3 4 5 6 7 8 9 10 11 12 Total

+5 +1.52 0 0 0 0 0 0 0 0 0 0 0 0 0

+4 +1.22 0 0 0 0 0 0 0 0 0 0 0 0 0

+3 +0.21 0 0 3 6 15 10 5 0 0 0 0 0 39

0 00 +2 +0.6 1 1 2 7 9 27 21 31 6 1 0 0 0 105 +1 +0.30 1 5 22 26 41 44 29 10 1 0 1 0 180

0 0 0 6 14 31 55 60 32 5 0 1 0 0 204

-1 --0.30 0 5 28 10 50 28 25 7 1 1 0 0 155

-2 -0.61 0 0 3 2 16 19 19 10 3 1 3 1 77

-3 -0.91 0 0 0 4 6 14 3 4 1 3 0 0 35

Total 2 18 77 88 210 196 144 42 7 6 4 1 795 Table 25. Analysis of covariance to test for a difference in means (percent razor clams per tide level transformed by an arcsin square root transformation) and whether one regression line can be used for all observations from the +4 to the + 1 foot ( + 1. 22 to +0.30 m) tide level among eight study sites in Sector 1, Cordova, Alaska.

2 2 L X LXY LY2 LY'

Within each group (2) 5 86.8400 1520.7029 12.4658

(3) 5 84.2450 1482.0495 62.6055

(4) 5 47.0600 956.9746 514.0459

(5) 5 97.2400 2129.8352 238.7117

(6) 5 106.9600 26 17.8556 329.7683

(7) 5 98.8500 2181.6450 227.3S05

(9) 5 75.3700 175 1.7654 615.6381

(10) 5 55.7100 971 .9433 35 1 .2225 Among means 0 0 65.0709 65.0709

Within groups 40 652.2750 136 12.7725 2976.2056 Total 40 652.2750 13677.8434 3041.2765 s l = 12.4658 + 62.6055 +. .. .+35 1 .2225 = 235 1.8383 s2 = 2976.2056 - 2351 .8383 = 624.3673 s3 = 65.0709 s4 = 0 n = number of observations in each group = 4

ST = 3041.2765 k = number of groups tested = 8

Test for difference in means Test for one regression line

s3 + s4 s2 + s3 + s4 K - 1 _2 (k -- _-<-) _ F = --:::--'-'--�-- F = ---'--::;- l 8 1 + s2 s 1 k(n - 1) - 1 k(n - 2)

F = 0.0718; F.95 (7,23) = 2.44 F = 0.3350; F.95 (14, 16) = 2.375 Conclusion: no significant difference in means; one regression line can be used for all observations.

109 Table 26. Analysis of covariance to test for a difference in means (percent razor clams per tide level transformed by an arcsin square root transformation) and whether one regression line can be used for all observations from the 0 to the -3 foot (0 to -0.91 m) tide level among five study sites in Sector 1, Cordova, Alaska.

�x2 �xy �y2 �y·2

Within each group (2) 5 19.6600 119.0084 41.7053

(3) 5 54.4650 711.9883 118.7011

( 4) 5 49.5600 629.3604 138.1217

(7) 5 53.2800 626.0277 58.2761

(9) 5 10.6000 50. 1 965 27.7245

Among means 0 0 10.3430 10.3430

Within groups 25 187.5650 2136.5813 729.3561

Total 25 187.5650 2146.9243 739.6991

s l 41.7053 + 118.7011 + ....+ 27.7245 = 384.5287

s2 = 729.3561 - 384.5287 = 344.8274

s3 = 10.3430

s4 = 0 n = number of observations in each group = 4

ST = 739.699 1 k = number of groups tested = 5

Test for difference in means Test for one regression line

F k(n - 1) - 1 k(n - 2)

F = 0.0496; F (4,14) = 3.11 F = 1.1545 ; F (8,10) = 3.07 _95 _95 Conclusion: no significant difference in means; one regression line can be used for all observations.

II0 in Orca Inlet relative to the Point Steele site, the sampling procedure revealed no clams at the +4 foot (+1.22 m) tide level in Orca Inlet. Tide level determinations for the Orca Inlet study plots were considered to be highly accurate and I felt that at the time of their final determination, tide level locations in Orca Inlet and at Point Steele were as precise as could be obtained with the methods employed (as confirmed by U.S. Coast and Geodetic personnel, Anchorage, Alaska, pers. comm.); therefore, no adjustments were made to the data.

Point Steele Beach sampling data from the 'C' series plots are presented in Table 27. Means and standard deviations of these data, adjusted to 1000 sq. ft. (92.9 m2), were derived using the method in Appendix 4. In my opinion, based on extensive field observations, the 'C' plot data depict a very realistic frequency stratification by tide level. I felt that most, if not all, clams within sampling frames were captured, since 97.4 percent were 1- and 2-year-olds, hence readily obtained by the screening method described.

A curve was fitted to the Point Steele data (Fig. 27). As seen from the plot of data points, the empirical curve is rather complex and a general gamma (r )distribution curve was used to obtain the best fit (Appendix 5). The fit of this curve is fairly good, except at the +2 foot ( +0.61 m) tide level, where the estimate is too high, and at the zero tide level, where the estimate is too low. The fitted curve does, however, fall within three standard deviations of th� estimated mean number of clams for these tide levels and, therefore, has much relevance to population estimation (discussed later under Survey Techniques).

The Katalla-Softuk sampling yielded further evidence of the negative binomial relationship of the stratification of razor clams by tide level (Table 28).

Since a negative binomial relationship was evidenced between the frequency of occurrence of razor clams and tide level in each study, it was desirable to determine the closeness in agreement among each of the sets of data including the gamma distribution obtained from the Point Steele data. Empirical data from the three areas of study were divided into two groups as were the estimated gamma distribution data. The two groups consisted of: (1) data obtained from the +3 to the +1 foot (+0.91 to +0.30 m) tide levels; and (2) data obtained from the zero to the -2 foot (-0.61 m) tide levels. Because lower tide level data were not obtained from study plot number 6, Orca Inlet, this block of data was not included in computations. Each set of data within the two groups was converted to percentages which, in turn, were transformed by an arcsin square root transformation. In this format, the data were subjected to analysis of covariance. Results of this analysis for both groups strongly implied that there were no real differences among the adjusted and unadjusted treatment means, and that one regression line could be used for all observations in each group (Tables 29 and 30). Therefore, the gamma distribution derived from the Point Steele data may be employed as a valid and representative estimate of the proportion of razor clam density by tide level for the Orca Inlet, Point Steele Beach and Katalla-Softuk study locations.

Estimates derived from the Point Steele gamma distribution are provided in Table 31. This material will be further discussed under population estimation (see section on Survey Techniques). An extrapolation of the Point Steele gamma distribution to 30 feet (9.14 m) below mean lower low water is presented in Table 32. The validity of this procedure to estimate clam densities at depths greater than 2 feet below mean lower low water is substantiated, in part, by dredge studies conducted in 1971 during which razor clams were captured to depths of 66 feet (20.12 m) below mean lower low water. A statement by Keen (1963 ), who inferred that razor clams have been recovered from depths to 180

Ill Table 27. Distribution of razor clams by tide level ± mean lower low water from "C" series study plots at Point Steele Beach, Hinchinbrook Island, Cordova, Alaska, growing ;trea, 1971.

Tide levels Sample ft. +5 +4 +3 +2 +1 0 -1 -1.5 -2 number m. +1.52 +1.22 +0.91 +0.61 +0.30 0 -0.30 -0.46 -0.61 Total

1 0 0 6 12 26 27 19 25 16 131 2 0 2 5 20 46 2E 19 12 6 136 3 0 0 9 12 43 27 9 9 14 123 4 0 0 6 10 15 24 23 11 89 5 0 2 10 9 17 25 10 17 90 6 0 1 8 6 30 33 19 20 117 7 0 0 13 6 13 24 20 76 8 0 2 11 16 9 2C 20 78

Total 0 7 68 91 199 206 139 46 84 840 - - N Tide level Means Standard ft. m. per 5 ft. 2 (0.4645 m2) per 1000 ft.2 (92.9 m2) Deviation

+5 +1.52 0 0 0 +4 + 1.22 0. 8750 1'75.0000 70.0765 +3 +0.91 8. 5000 1700.0000 196.3961 +2 +0.61 11.3750 2275.0000 340.0367 +1 +0.30 24.8750 4975.0000 983.7519 0 0.0 25.7500 5150.0000 261.1786 - 1 --0.30 17.3750 3475.0000 356.4458 -- 1.5 -0.46 15.3333 3066.6600 982.0613 - ' --0.61 14.0000 2800.0000 403.3196 6000

5000

4000

(/) E res ..--u

4- 0 3000 S- Q) I ..0 ' E I I :::l ' :z: ' w 2000 'r /r 1000 '/ 0 = Point Steele Beach samnling data �

v = r Gamma distribution

+5 +4 +3 +2 +1 0 -1 -2 - 3 Tide levels (feet) relative to mean lower low water (0)

Fig 27. Comparison of a general gamma distribu tion curve fi tted to Po in t Steele Beach, Cordova, Alaska, ra zor clam fr equency of occurrence by tide level data. Table 28. Distribution of razor clams by tide level ±mean lower low water from Katalla and Softuk beaches, Cordova Sector 4, 1971.

Number Number Mean per Mean per Tide level of of 5 ft.2 1000 ft.2 Standard ft. m. clams samples (0.4645 m2) (92.9 m2) Deviation

+3 +0.91 2 6 0.3333 66.6600 42.1 426

+2 +0.61 5 6 0.8333 166.6600 61.4491

+I +0.30 7 6 1.1666 233.3200 120.1831

0 0.0 15 6 2.5000 500.0000 169.3044

-1 -0.30 13 6 2.1666 433.3200 120.1831

-7 -0.61 3 3 1.0000 200.0000 115.4G42

Total 45 33 7.9998 1599.9600 ± 276 .4704

114 Table 29. Analysis of covariance to test for a difference in means (percent razor clams per tide level transformed by an arcsin square root transformation) and whether one regression line can be used for all observations from the +3 to the +1 foot (+0.91 to +0.30 m) tide level as pertains to sampling data of (1) Orca Inlet study sites; (2) Point Steele Beach "C" seriespl ots; (3) Katalla - Softuk beaches; and (4) the gamma distribution derived from Point Steele "C" plots.

:Lx2 LXY :Ly2 :L y'2

Wilhin each group (1) 2 19.5400 207.2408 16.3350

(2) 2 22.3800 280.9875 30.5553

(3) 2 22.7800 265.7885 6.3243

(4) 2 20.6600 219.4 178 6.0000

Among means 0 0 0.03 57 0.03 57

Within groups 8 85.3600 973.4346 62.6433

Total 8 85.3600 973 .4703 62.6790

= 16.3350 + 30.5553 + 6.3243 + 6.0000 = 59.2146 s2 62.6433 - 59.2146 = 3.4287

= 0.03 57 s4 62.6790 - 62.6433 - o.o357 o 62.6790 n observations in each group 3; k groups tested = 4

Test for difference in means Test for one regression line

s2 + s3 + s4

_2_,( �k -_l-'-) __ F F = :::- S r k(n - 1) - 1 k(n - 2)

F = 0.0013; F (3,7) = 4.35 F = 0.0390; F (6,4) = 6.16 _95 _95 Conclusion: no significant differences in means; one regression line can be used for all observations.

115 Table 30. Analysis of covariance to test for a difference in means (percent razor clams per tide level transformed by an arcsin square root transformation) and whether one regression line can be used for all observations from the 0 to the -2 foot (0 to -0.61 m) tide level as pertains to sampling data of (I) Orca Inlet study sites; (2) Point Steele Beach "C" series plots; (3) Katalla - Softuk beaches; and (4) the gamma distribution derived from Point Steele "C" plots.

:z:x2 :Z:xy :z;y2 2: y'2

Within each group (I) 2 11.35 65.1 117 0.7004

(2) 2 17.57 154.44 13 0.0888

(3) 2 25.93 392.9162 56.7338

(4) 2 8.70 38.3971 0.5521

Among means 0 0 1.9052 1.9052

Within groups 8 63.55 650.8663 146 .0409

Total 8 63.55 652.7715 147. 946 1 sl 0.7004 + 0.0888 + 56.7338 + 0.5521 58.0751 s2 146.0409 - 58.0751 = 87.9658 s3 1.9052 s4 147.9461 - 146 .0409 - 1.9052 0

ST = 147.9461

= n = observations in each group 3 '· k groups tested 4

Test for difference in means Test fo r one regression line

F

k(n - 1) - 1 k(n - 2)

F = 0.0304 ; F.95 (3,7) = 4.35 F = 1.0317; F.95 (6,4) = 6.16 Conclusion: no significant difference in means; one regression line can be used for all observations.

116 Table 31. Regression estimates of razor clam frequency of occurrence by tide level on the low tide terrace derived from a gamma distribution fitted to Point Steele Beach ''C" series plot data, Cordova, Alaska.

(1) (2) (3) Tide levels Density in clams Relative clam relative to mean per 1 000 ft. 2 density expressed lower low water (92.9 m2) in proportion feet meters

+5 +1.52 0 0

+4.5 +1.37 14 0.0003

+4 +1.22 179 0.004 1

+3 .5 +1.07 653 0.01 50

+3 +0.91 1422 0.0327

+2.5 +0.76 2340 0.0539

+2 +0.61 3214 0.0740

+1.5 +0.46 3912 0.0900

+1 +0.30 4342 0.0999

+0.5 +0. 15 4506 0.1037

0 0.0 4424 0.1018

-0.5 -0.15 4165 0.0959

-1 -0.30 3772 0.0868

-1.5 -0.46 33 19 0.0764

-2 -0.61 2844 0.0655

-2.5 -0.76 2385 0.0549

-3 -0.91 1959 0.045 I

Sums 43450 I .0000

I 17 Table 32. Extrapolation of the Point Steele Beach "C" plot series gamma distribution of razor clam density by tide level from the low tide terrace to subtidal depths, Cordova, Alaska.

Tide level ±mean Estimated number of lower low water razor clams per 1000 ft.2 or feet meters 92.9 m2

+5 +1.52 0.00000 +4 +1.21 179.11539 +3 +0.91 1422.29688 +2 +0.61 3214.1 1499 +1 +0.30 4341.89063 0 0.00 4424.39844 -1 --0.30 3772.1 0059 -2 -0.61 2843.58154 -3 --0.91 1958.983 89 -4 -- 1.22 1259.85205 -5 -1.52 767.42944 -6 -1.83 447.39478 -7 -2.13 251 .53537 -8 -2.44 137.17865 -9 -2.74 72.89793 -10 --3.05 37.88243 -I I -3.35 19.30687 -12 -3.66 9.67301 -13 -3.96 4.77345 -14 --4.27 2.32401 -15 --4.57 1.11786 -16 --4.88 0.53 184 -17 --5.18 0.25054 -18 --5.49 0.1 1696 -19 -5.79 0.05415 -20 -6. 10 0.02488 -21 --6.40 0.01 135 -22 -6.71 0.00515 -23 -7.01 0.00232 -24 --7.32 0.00104 -25 --7.62 0.00046 -30 -9. 14 and greater depths, abundance less than 0.00001

118 feet (54.86 m) below mean lower low water, lends further credence to this procedure. The dredge studies are discussed later, under the section entitled Survey Techniques.

Estimated Upper Habitable Tide Levels

Table 33 provides estimates of the upper habitable tide level relative to mean lower low water for razor clam growing areas from California to the Bering Sea. This table was compiled from my data for the Cordova area, published data on tidal regimes and material presented by Tegelberg (1964 ), Bourne (1969) and Bourne and Quayle (1970). My estimates are based on the ratio of the uppermost habitable tide level in the Cordova area (+4.5 ft. or +1.37 m above mean lower low water) and the mean tide level at Cordova (+6.40 ft. or + 1.95 m) relative to mean lower low water, to the same ratios for geographical areas in question. Though speculatory in nature, these estimates appear to portray a realistic view of this parameter. Substantiating evidence is presented in the following section dealing with substrate and exposure.

Apparent Affects of Substrate and Exposure on Razor Oam Survival and Density on the Low Tide Terrace

The Copper River contributes a tremendous quantity of sediments to razor clam growing areas of Cordova, Alaska (Fig. 9, page 43). In 1958 Orca Inlet razor clam populations experienced heavy mortalities; cause of the die-off is unknown. Some local clam diggers attributed the mortality to heavy 'siltation' from spring breakup of the Copper River. Others thought that a mysterious 'green ooze' was the culprit. During 1971, a commercial razor clam digger called my attention to what was described as the same type of 'green ooze' and samples were collected and analyzed. They contained the expected constituents of aquatic bottom material including diatoms, sand particles, algae and protozoa. In addition, a nonpathogenic (to humans) variety of staphylococcus and nonspore forming, nonpathogenic (to humans) anerobic, gram-positive rods were identified. No mortalities were observed following this bloom, thus the 'green ooze' was probably not linked with the 1958 decline.

Heavy siltation may have been implicated to some extent in the mass mortalities. The Copper River discharges 107.5 x 106 metric tons of suspended sediments per year (Reimnitz, 1966 ). This river heads on the north flank of the Wrangell Mountains and its past history and present behavior is largely controlled by glaciers (Reimnitz, op. cit.). Its mountainous, glaciated drainage basin contributes a large amount of fresh rock flour and this river has comparatively low water temperatures, varying between 46.4° F. and 53.6° F. (8° C. and 12° C.) (Reimnitz, op. cit.). Chemical weathering is greatly retarded at low temperatures and with it the formation of clay (Jenny, 1941; In Reimnitz, 1966:44 ). Gravity cores taken by Reimnitz (op. cit.) on the Copper River Delta revealed an extensive zone of well-sorted, medium- to fine-graded sand interbedded with clayey silt layers. Discharge of an inordinately large volume of clayey silt material along the Copper River Delta during spring 1958 may well have occurred and may well have been linked with the clam mortalities.

The March 27, 1964 earthquake occurred at low tide when large portions of the tidal flats were exposed. An uplift of nearly 6 feet (2 m) was associated with the earthquake at Cordova. Tsunamis and seiches, as high as 24.6 feet (7 .5 m) at Cordova, eroded at least 29.92 inches (76 em) of surface sediment over large portions of the tidal flats (Reimnitz, op. cit.). At this writing, extensive tidal areas along Orca Inlet reveal exposed clay layers. These areas are located windward to poorly producing razor clam beds. It appears that surface currents remove clay fractions from exposed layers and redeposit

119 Table 33. Estimated upper habitable tide level (relative to mean lower low water) at various razor clam growing areas based on the ratio of the uppermost habitable tide level at Cordova, Alaska (+4.50 feet), and the mean tide level at Cordova, Alaska ( +6.40 feet).

Estimated upper habitable tide Growing area level

Polly Creek Beach (Cook Inlet, Alaska) 6.26

Swikshak Beach (Alaska Peninsula) 4.85

Cordova, Alaska 4.50

Yakutat, Alaska 3.73

Dixon Harbor (Southeast Alaska) 3.66

St. Paul Harbor (Kodiak, Alaska) 3.09

Izembek Lagoon (Bering Sea-Alaska Peninsula) 1.83

Masset Harbor (Graham Island, British Columbia) 4.64

Point Chehalis, Washington 3.38 Long Beach, Washington 3.09

Warrenton, Oregon 3.09

Port Orford, Oregon 2.74

Crescent City, California 2.60

Pismo, California 1.97

120 them in adjoining areas supporting marginal razor clam stocks.

In this study, I attempted to determine the relationship among clam densities, substrate, and tide level exposure at Point Steele Beach. One- and two-year-old razor clams can readily be found within the top 4 to 5 inches (approx. 10 to 12 em) of surface substrate in the Cordova growing areas during the spring and summer months. Surface cores on the low tide terrace were collected using a 12-ounce juice can with both ends removed. Thls provided substrate core approximately 2.50 by 4. 75 inches (6.5 by 12 em). Subtidal substrate samples were taken off Point Steele Beach with a Ponar grab ; depth of water was determined by fathometer.

A graduation of substrate grain size occurs along the beach profile due to the process of "slope sorting" and coarser materials are usually found at higher intertidal beach zones (U.S. Army, Corps of Engineers, 1966). This is illustrated, to some degree, by substrate collections from Point Steele and Swikshak beaches (Tables 34 and 35).

A multiple regression analysis was performed in regard to mean substrate diameter; exposure, as reflected by tide level (0 to +5 ft .); and mean number of clams per 1000 sq. ft. (92.9 m2) by tide level using Point Steele Beach data. Frequency of occurrence of clams was designated as the dependent variable, X 1 ; tide level and sand grain diameter were the independent variables, designated X2 and X3, respectively.

Thls analysis yielded a coefficient of multiple correlation, R1.23 = 0.9716 with standard deviation, S1.23 = 533. Coefficients of partial couelation were: q 2 = -0.9656; q 3 = -0.7076; and r23 = 0.7171. Utilizing the t-ratio to test the significance of the partial correlation coefficients it was found that t for q 2 = 5.4298; to.025 v3 = 4.541 (sign of t ignored for a two-tailed test). However, for r13 and r23, the t values were 1.7343 and 1.7821, respectively, which were significant only at the 0.2 level of probability. Therefore, although the degree of tide level exposure appeared to be a highly important variable, sand grain diameter, within the size range evidenced at the Point Steele site, could not be considered with assurity an important variable. Fig. 28 depicts the relationship among exposure of the low tide terrace, based on 150 morning tides from April through August 1971; mean sand grain diameter; and the abundance of clams by tide level. In regard to the analysis of substrates from different beaches (Appendices 6a to 6g) the reader will notice that in several instances where the percent materials passing through seive #200 is less than 2 percent, the 0.02 mm and, on two occasions, the 0.005 mm particle size, as determined by hydrometer test, were higher than the percent passing the #200 seive. Since the #200 seive opening is 0.074 mm it follows that the percent ) 0.02 mm must always be smaller. The reason this trend was not evidenced was because salt in the tide-sand samples was dissolved in the hydrometer solution making it heavier, so that the reading was higher by between 1 and 1 1/2 percent. Presuming this is all the error, the percent passing through the #200 seive can be taken as "true", less about 1 percent from the hydrometer readings.

) Sands were classified in the following manner. Coarse sand was that retained by the #1 0 seive after passing through #4 ; medium sand passed #1 0 and was retained by #40; fm e sand passed #40 and was retained by #200. Silts and clays passed through #200. Silt particles were considered to be less than 0.02 mm and clay particles were considered to be less than 0.005 mm.

) Significant differences in grain diameter distribution seemed to occur in sizes above those where hydrometer tests were needed. For example, in comparing sand from Point Steele

121 ) Table 34. Analysis of substrate obtained from Point Steele Beach, Cordova Sector 1, 1971, from +5 to -16.5 feet (+1 .52 to -5.03 m) relative to mean lower low water.

Tide level Mean Sand ft. m diameter (mm)

+5 +1.52 0.1812

+4 +1.22 0.1 783

+3 +0.91 0.1874

+2 +0.61 0.1 654

+1 +0.30 0.1635

0 () ()() 0.1681 -1 -0.30 0. 1633

-16.5 -5.03 0.1 623

122 Table 35. Analysis of substrate obtained from Swikshak Beach, Alaska Peninsula, September, 1970, at tide levels estimated to be between mean lower low water and the +3 foot (+0.91 m) tide level.

Percent materials passing through the respective screen

Sample Sample Sampl Sample Sample3/ Sample Screen Size la .!J ab 2a eY 2b 3a 3b

0.742 inch 100 100 100 100 100 100

#4 97.4 99.6 93.6 89.5 86.6 93.1

#8 97.0 99.0 90.2 86.7 85.9 92.4

#20 96.6 98.5 87.0 83.8 85.1 91.6

N w #35 95.9 97.8 83.7 80.8 83.6 89.9

#65 68.1 67.2 41.4 40.8 34.1 36.7

#100 19.3 18.2 10.4 10.5 6.2 7.2

#150 4.5 4.1 2.1 2.0 1.1 1.5

#200 0.7 0.6 0.4 0.3 0.2 0.5

<#200 0.04 0.04 0.04 0.04 0.04 0.33

--

Samples labeled "at water level." Jj Samples labeled "30 yards from water level." J:.l Samples labeled "50 yards from water level." }j 100 0.20 -·r 25 I '""'\ --- - Clams

Expos ure "'\ / 0 0 0 0 Sand 0. 19 / \ 20 \ uQ) c ( \ (IJ E I L E \ L �so 1 I :::J \ u L . \o I u Q) E \ 0 +- . 0 I EQ) 0. 18 (IJ 60 I \ I 5 +- (IJ 0 0 \ 0 · 1.!\ I >- u- u �- \ c c I \ Q) (]) :::J (IJ- E \ o- L · CJ) +-- I \ L(]) +- u 0. 17 40 I '\ I 0 c 2:' E (IJ :::J I \. (IJ N (j) (j) 0 0 I \. - c o_ ' u (\) X I 0 +- (]) (]) ' c 2: I ' (]) +- 0 u c I ' 0 ' L (]) (]) 0. 16 � 20 I 5 Q_ (]) I Q_ I I I _1 I - 15 0 0. I 6 5 4 3 2 I z -I -2 - 3 - 4 -16.5 Tide Leve ls

Fig. 28. Frequency of tide level exposure, mean sani grain diameter, and abundance of razor clams by tide level at Poin t Steele Beach, Hinchinbrook Island, Alaska. Beach, where screening yielded high densities of 1- and 2-year-old clams, and Concrete Bar, where no young clams have been recovered by screening or by other methods for five consecutive years, they would both classify as fine sands, but that from Concrete Bar was over 60 percent finer than #80 seive size (0.007 inches or 177 microns) and ± 3 5 percent finer than # 100 seive size (0.0059 inches or 149 microns). In other words, that from Concrete Bar was a graded fine sand. Concrete Bar also shows six to eight times as much substrate passing through the #200 seive. About 80 percent of Point Steele sand was predominantly one size, i.e., 177 microns.

Of further interest, Table 36 shows the mean diameter of substrate and the proportions of fines, silts, and clays at mean lower low water collected from several razor clam beds in the Cordova area. Neither 1-nor 2-year-old razor clams have been recovered by screening from Rockslide Bar or Concrete Bar for five consecutive years (1969 to 1973 ), indicating a very low level or a complete absence of these age classes. Very few 1- and 2-year-old clams were screened from Inside Ocean Bar. and Shirttail Bar over the same time period. All four areas contain >2 percent clay fractions . In comparing the proportion of clay fractions from areas where screening has and has not yielded 1- and 2-year-old clams, that is, Concrete and Rockslide fractions versus the fractions evidenced in the remaining locations listed in Table 36, t = 2.08>to.l; v8 = 1.86, thus establishing that the observed difference co nlcl h�vP �risPn hy r.h�nr.P in ]p.c:;c:; th::m 1 0 percf.'nt of triills. Tn addition, Table 37 presents the relationship between density of 1-year-old razor clams and the amount of clay fractions within the top 4 inches (1 0.16 em) of the substrate surface. As evidenced, a very significant coefficient of linear correlation is obtained. Therefore, on the basis of the data presented, the author feels that a critical region for lethal levels of fine substrate particles <0.005 mm in diameter may be approximately 2.2 percent of the total substrate composition. Levels of clay fractions in this proportion may cause suffo cation in early life stages of razor clams.

In regard to the overall analysis of the various substrates in the aforementioned tables, Jim Lindsey (Director, Soils Laboratory, Alaska Department of Highways, Valdez, Alaska, January 1972, pers. comm.) had the following comments. " ... There is no cohesiveness as we would define the term. In fact, they are excellent examples of cohesionless material. With respect to the property of stability or load impact resistance, these materials have plenty of that as long as they are laying as they 'want to' with surface in equilibrium, so to speak, with the rhythmic forces of the ocean. This stability is witnessed when one gallops a horse or drives a vehicle on the wet part of the beach. Any abmpt forms these sands might accidentally take would not withstand the first rain let alone breakers, but once even with the surrounding su rface this material should be the most stable of non-cemented fine grained mass es."

Thus far we have established that: (1) density of razor clams on the low tide terrace is stratified by tide level; (2) upper limits of the habitable range on the low tide terrace appear to be related to tidal regimes; and (3) data on substrate and exposure on the low tide terrace appear to tie (1) and (2) together. Now we will consider age, length, and growth-increment in valve length as they relate to habitable levels on the low tide terrace.

Age by Tide Level Hirschhorn (1962 :4 7) indicated that " ...co mmercial catches originating on off shore bars frequently contain older age groups in higher proportions than do inshore catches ....," but he presented no measurable data.

1 25 Table 36. Mean diameter of sand obtained from the mean lower low water level of several razor clam beds in the Cordova area during 1971, and the resultant proportions of fines, silts, and clays.

% 0.074 X to Diameter 0.020 % % (mm) (mm) Silt Oay

Point Steele Beach 0.1681 0.40 0.54 0.23

Softuk Beach 0.1 624 0.20 0.70 0.30

Big Point Bar 0.1579 1.13 0.13 1.60

Inside Ocean Bar 0.1571 1.53 0.43 2.00

Southwest Ocean Dar 0.1530 0.46 0.80 O.GO Shirttail Bar 0.1522 0.73 0.33 2.17

Katalla Beach 0.1471 1.00 0.40 0.60

Rockslide Bar 0.1334 3.83 0.60 2.27

Concrete Bar 0.1300 4.53 0.50 2.20

Canoe Pass Trail Bar 0.1 166 6.17 0.33 1.80

126 Table 37. Relationship between the density of 1-year-old razor clams per 5 sq. ft. (0.46 m2) at mean lower low water and the mean percent of fine substrate <0.005 mm at the same datum plane for seven growing areas in Cordova Sector 1.

X% Substrate <0.005 mm X No. clams/5 ft.2 X y

1. Point Steele Beach 0.85 22.47

2. Big Point Bar 1.60 1.66

3. Canoe Pass Trail Bar 1.80 1.00

4. Inside Ocean Bar 2.00 0.33

5. Shirttail Bar 2.16 0.00

6. Concrete Bar 2.20 0.00

7. Rockslide Bar 2.26 0.00

Coefficient of linear correlation, r = -0.9124

Testing for the significance of the correlation coefficient:

= rJN-2 = t =4.9846; t.Ol v5 4.03 � Conclusion: The observed value of the correlation coefficient is significant at the 1 percent level. Oay fractions appear to be critical variable.

127 To test Hirschhorn's observations, 482 razor clams from the Orca Inlet study plots were examined to determine if and to what extent the average age, as determined by counting the annual rings, varied by tide level. Age determination of razor clams by the annual ring method has long been employed as an indicator of age (references, page 42).

Analysis of variance of age (for dug razor clams in their nth year of life) by tide level strongly implied that older clams are found at lower tide levels (Table 38).

The regression equation, Y = -0.2257 X+ 6.7727, yielded the age quantities by tide level [where X at the +3 ft. (+0.91 m) tide level = 7; and X at the -3 ft. (-0.91 m) tide level = 1] with a coefficient of linear correlation, r = 0.8484 (Table 39). The correlation coefficient is significant at the I percent level. The importance and employment of this statistic as pertains to yield calculations will be shown later under Survey Techniques.

Total Valve Length by Tide Level Hirschhorn (1962:21) obtained samples fr om Oatsop beaches, Oregon, that " ... indicated a tendency toward larger shell size at lower beach levels, but slopes of regression failed to reach statistically significant probability levels (less than 5 percent) .... "

To determine if total valve length could be a function of the tide level from which resident clams were obtained, 288 specimens from the Orca Inlet study plots were examined. Measurements were recorded to the nearest millimeter with vernier calipers. All razor clams for this analysis were collected within a 6-day period, June 28 to July 3, 1969. It was assumed that no significant differences of growth increment in the length of the valves had occurred among the specimens from day one to day six.

Analysis of variance of unweighted razor clam valve length (mm) for dug clams by tide level definitely indicated that larger clams were found at lower tide levels (Table 40). The regression of unweighted razor clam valve length by tide level, Y = 4.45·17 X + 100.9671, [where X at the +3 ft. (+0.91 m) tide level = 1; and X at the -3 ft . (-0.91 m tide level = 7] has a coefficient of linear correlation, r = 0.8561. When equal weighting by percent abundance was applied to mean length weighted by age, the resultant regression, Y = 3.4455 X + 107.1320, (where X has the same values as above) yielded a coefficient of linear correlation, r = 0.8552. Correlation coefficients of both regressions were significant at the 1 percent level. Quantities from both regressions are found in Table 39. The importance and application of this statistic as it pertains to yield calculations will be shown later under Survey Techniques.

Growth Increment in Valve Length by Tide Level

Tegelberg (1964:77) presented data showing that growth increment is slower at the plus 3-foot tide level, " ... slightly slower at the minus 2.5 foot level"; and " ... best growth appeared to occur near the 0-tide level...."

An analysis of increment in growth of valve length by time period, relative to various tide levels and year classes of razor clams obtained from Orca Inlet study plots, produced a variety of results. It seemed logical to assume that razor clams at lower tide levels, having more nutrient-bearing sea water flowing over them than their cohorts at upper tide levels, would have more time to feed, and thus would attain a faster rate of growth. Oams from several different tide levels and study plots were examined to substantiate this assumption. Presumably because of small sample sizes study results were inconclusive (Appendix 7).

128 Table 38. Analysis of variance of razor clam age (years) by tide level as determined from study plots in Cordova, Alaska, Sector 1, 1969.

df Sums of Squares

Among means 6 115.6869

Within groups 475 1137.0206

Total 481 1252.7075

115.6869/6 F = = 8.0549 > F.99(6,475) = 2.80 1137.0206/475

Conclusion: Samples were drawn from sources whose average values differed significantly from each other.

129 Table 39. Regressions of razor clam age and total valve length by tide level as determined from study plots in Cordova, Alaska, Sector 1, 1969.

Tide Level Age Length (mm) Length (mm) (1 - foot elevations) (years) (unweighted) (weighted) 11

Plus three 5.19 105.42 110.58

Plus two 5.42 109.87 114.02

Plus one 5.64 114.32 117.47

Zero Jj 5.87 118.77 120.91 Minus one 6.10 123.23 124.36

Minus two 6.32 127.68 127.80

Minus three 6.55 132.13 131.25

r value 0.85 0.86 0.86

Equal weighting by percent abundance applied to mean length weighted by age . �/ Mean lower low water. .Jj

130 Table 40. Analysis of variance of unweighted razor clam total valve length (mm) by tide level as determined from study plots in Cordova, Alaska. Sector 1 1969 '

df Sums of Squares

Among means 6 25,252.2505

Within groups 281 123,216.9961

Total 287 148,469.2466

25,252.2505/6 F 9.5981 > F.99(6,281) = 2.88 = 123,216.9961/281 =

Conclusion: Samples were drawn from sources whose average values differed significantly from each other.

1 31 Fecundity

To manage a razor clam population so it is self-regenerating and capable of maintaining relative abundance in spite of delimiting ecological and exploitive factors (e.g., substrate and exposure and harvest, respectively), it is essential to understand its fertile egg production in terms of the age and size structure and abundance of that population. Obviously, before this can be determined it is necessary to measure egg production of individual clams comprising the population.

Probably the most accurate means of determining the total number of ova in the gonads of razor clams is that suggested by G. E. MacGinitie (Professor Emeritus, California Institute of Technology; pers. comm., 1971) . First, remove the ovaries and carefully excise the digestive tissues from them ; next, weigh the ovaries; then from various representative parts of the ovaries, cut off tiny pieces, weigh each on a microbalance, count the ova in each piece under a microscope, average the results and use this figure to compute the total number of ova in the ovaries. Repeating this procedure on clams of different sizes should give a close approximation of the ova produced. This method was not employed by the author due to budgetary restrictions, but is presented here for those who would like to apply it.

The following fecundity estimates were derived from indices of weight loss attributed to spawning. Fecundity estimates of razor clams from Copalis Beach, Washington, kindly furnished by Mr. Herb Tegelberg (Biologist, Washington Department of Fisheries, pers. comm., 1971) tend to substantiate these estimates.

The method for deriving the weight of a single razor cla.m ov1..1m is shown in Appendix 8. Higher coefficients of correlation were obtained from Cordova Sector 1 length-weight relationships than those from Sector 4 (Tables 21 and 22; pp. 83 and 84 ), hence fecundity estimates are based on the former. My estimates are based on the assumption that fecundity in the razor clam is proportional to the body weight [ see Beverton and Holt (1957) for discussion] . For estimates with growth in continuum, length increment for specific age classes was first calculated by time period fo r 425 specimens. Next, the seasonal growth in valve length from the last formed annulus was determined. Thus, specific lengths by age class were obtained which were then applied to respective regressions (derived from 187 specimens) for those particular time periods to determine related weights. Following this procedure, resulting weight loss was obtained (Table 41 ). Finally, weight loss by size class was converted to numbers of ova by size class from which regression estimates were made. Observed weight loss by size/age class is shown in Fig. 29.

By applying the regression equation in Fig. 10, page 50, to the necessary values for July 24, 1971 (i.e., seawater temperature, 48.6° F.; day 52), it was estimated that 55.83 ± 15.52 percent (.99 C.I.) had not begun to spawn. Conversely, it was estimated that 44. 17 ± 15.52 percent had begun to spawn. The observed weight loss was assumed to be a reflection of this activity. If it is further assumed that all clams spawn at a rate proportional to size, a ratio can be formed with the spawning regression data for July 24 and the observed weight loss shown in Fig. 29. For example, an observed weight loss of 0.89 g is comparable to about 2.3 million ova. Thus, if 2.3 million ova represent the average weight loss per female of 44.17 ± 15.52 percent of actively spawning clams of a specific size class then n ova per female should approximate the weight loss of 100 percent of size-specific completely spawned clams. In this manner lower, mean, and upper estimates were obtained with three standard errors separating the mean from lower and upper estimates (Table

132 Table 41. CalculaJed weight loss durlng the spawning period of razor clams from July 5 to July 24, 1971, in Cordova Sector I.

Pre- Post Post Pre- Spawning Spawning Spawning Spawning Mean Mean Mean Mean Weight Length Weight Total Net Length (grams) (mm) (grams) Weight Length at day at day at day at day Loss Gain 186.5.!1 186.5 203.52/ 203.5 (grams) (mm)

98.3444 66.904 79840 101.0628 65.57807850 1.32671990 2.7184 w w 111.9956 1 02.002 73 800 113.6768 97.463404 70 4.53933330 1.6812

126.9416 153.1 5352000 127.7950 144.49565000 8.65787000 0.8534

134.5454 184.86816000 135.3682 1 7 5.464 20000 9.40396000 0.8228

137.1998 197.05478800 137.9426 187.01 862000 10.0361 6800 0.7428

Pre-spawning mean lengths and weights recorded on July 5 and 6, i.e., 186.5 days from January I. ll Post spawning mean lengths and weights recorded from July 21 to 24, i.e., 203.5 days from January 1. ]:/ Fig. 29. The rela tionsh ip among razor clam weigh t, seawater temperature, and time with gro wth in con tinuum .fo r partial application to fe cundity estimates. r--

bJ) ...-' UJCO Ulf'-. ON

,-... � Seawater Temperature ( °Fahrenhei t) .woo >-. cr-.. .w <1) 38.9 4 .1 49 .0 48.6 '-" QJ N .C '"O 3 so .s 48. 8 � 6 bJ) .c Q) :>-. •rl 0 .w H <1J Q) .1-J bll CO U'"O ;3 cr-.. p If) Q)C'J •rl 0 '"0 � .w QJN >-. .c :> � Q) <1) .w� H� :>'"0 bJ) Q) � p >-. Ul >-. <1) .w Q) <1) .0 <1) > <1) ....:1 '"0 0'"0 200 ·�- 1 /"'-..... I 141.1 9.9 10 .20

,-... Ul t-138 .9 11.6 9.40 s / / ...... <1) H Age Valve Length (mm) bJ) nth At day At day w ...-' Year 1 112. // /"'-..... ll- 131. 1 3.8 8.60 -!::>. .1-J l SO s s .c bJ) 1 1. 2 ·rl 8 3 1 33.9 Q) ;3 7 127. 3 130.9 � <1) ./"" ___. l-121.0 21. 1 4.SS .w 0 6 117. 7 123.2 H 100 � r 112 .9 30.S 1. 33 99.9 104 .7 / s _,..--.....- so � 4 82 .4 86 .S ----- 82 .4 23.0 0.89

3 S9 .4 r

so 100 150 200 25 0 Time (Day s beginning January 1, 19 71) 42). Also shown in Table 42 are regression estimates derived from a length-fecundity relationship for Copalis Beach, Washington, razor clams calculated in 1939 by an unknown investigator. The Copalis Beach data furnished by Mr. Tegelberg (op. cit.) are based on a sample size of 19 clams, but it is unknown by what method the estimates were made. Mr. Tegelberg indicated that he was unable to procure the original data from which the regression was made. I obtained points estimated from the Copalis Beach regression line and determined the approximate slope of the line with another regression having a coefficient of linear correlation, r = 0.9516, and standard error of estimate, Sy.x = 3,777,434 ova. Estimates presented in Table 42 are rounded. It should be noted that the Copalis Beach clams ranged from 89 to 129 mm in total valve length and had a corresponding fecundity range estimated from 2.5 to 42.7 million, respectively. It is apparent that the lower estimates of fecundity obtained from Cordova Sector 1 compare favorably with those from Copalis Beach, hence the lower estimates will be considered more valid than the mean and upper estimates.

Mortality and Survival

Mortality and survival rates are of paramount importance in dealing with razor clam populations, especially in Alaska growing areas where productive spawning of strong year-classes is the exception rather than the rule. To manage our populations of varying year-class strength, maximum sustainable yield will fluctuate in accordance with successful cohorts and calculation of this statistic must be carefully applied.

Estimated rates of fishing mortality were calculated from the Little Mummy Island density indicator study (discussed later under Survey Techniques), in which 50 marked clams were planted at known locations and subsequently observed on 28 occasions. Based on the observed 35 surviving clams, ranging from 4.5 to 6.0 in. (114 to 152 mm) in total valve length, the mean percentage of clams that could have been captured (relying on 'show' alone) was 69.18 ± 19.55. This means that on an average day, when weather conditions permit digging at the Little Mummy Island site, one could expect that 49.63 to 88.73 percent of the clams in that area would be showing to varying degrees, and thus theoretically be subject to capture. Fortunately for razor clams, weather and 'show' conditions (discussed under Survey Techniques) in the Cordova area are such that low harvests generally prevail. Application of these fishing mortality rates to other areas falls outside the realm of this study, but may be used as a guide subject to the discretion of the investigator.

From the preceding, lower, mean, and upper rates of exploitation coupled with natural mortality can be calculated by a = m + n - mn, where a = total annual mortality rate, ) m = annual mortality rate from fishing, and n = annual mortality rate from natural causes (Ricker, 1958 ).

All of the 3 5 surviving clams that were marked for the Little Mummy Island density indicator study were listed in good condition and without old or new injury prior to planting them, except as indicated below: ) #14 - "Acceptable condition, but slightly weak."

#33 - "Acceptable condition, but has slight fracture at posterior of right and anterior of left valve."

) #3 5 - "Acceptable condition, but has slight fracture at anterior of right valve."

135 ) Table 42. Razor clam fecundity estimates from Copalis Beach, Washington, 1939, and Cordova, Alaska, 1971.

Estimated number of ova (millions) by size class Copalis Cordova Beach Valve length mean lower mean upper (mm) estimate estimate estimate estimate

40 0.3 0.4 0.7

50 0.8 1.0 1.6

60 1.6 2.1 3.3

70 2.9 3.9 6.0

80 4.9 6.6 10.1

90 7.8 10.5 16.1

100 7.4 11.8 15.9 24.4

110 16.7 17.I 23.1 35.4

120 25.9 24.1 32.5 49.9

130 35.2 33.0 44.5 68.3

140 44.4 44.2 59.5 91.4

150 57.9 78.1 119.9

160 74.6 100.6 154.5

170 94.6 127.7 195.9

180 118.5 159.9 245.4

136 #40 - "Acceptable condition, but has old damage in posterior dorsal region."

#44 - "Acceptable condition, but has slight fracture in posterior ventral region." There were six marked clams that were definitely known to have died during the course of the study. Three of these were listed in good condition and without old or new injury prior to planting them; the condition of others is indicated below:

#6 - "Very weak."

#19 - "Acceptable condition, but has new and old fracture at posterior of left valve."

#37 - "Acceptable condition, but has old fractures on both valves in the posterior region."

Theremaining nine clams that were not recovered but presumed dead consisted of seven individuals that were listed in good condition and without old or new injury prior to planting, and two described as follows:

#26 - "Acceptable condition, but has very slight fracture at posterior of left valve."

#49 - "Acceptable condition, but has slight fracture at anterior and posterior of left valve."

It should be emphasized that no clams were marked and planted in which mantle damage and drainage of body fluids were evidenced.

Upon examination of the survivors that were planted having slight injuries, #14 was found to be in visibly good physical condition; a nacreous layer had grown over the damaged areas of #33 and #35, forming chambers containing sizeable quantities of sand grains; and a nacreous layer had covered the damaged areas of #40 and #44 without forming chambers.

Data specifically from Little Mummy Island razor clams (See Survey Techniques, page 144) yield the following values:

Intercept = 6.118 L= 153 mm K = 0.426 k = 0.653 to = 2.55 A.95 9.58 From the above values the natural mortality rate of Little Mummy Island clams can be estimated by employing Taylor's formula in which the appropriate estimate for maximum natural mortality for simple population models is :

= e-Mt where t = A.95, or:

M 2.996/A.95

137 or: 2.996K M = -=-':.::--::-;;,.:-=--=-- 2.996 + Kt0

The maximum rate of natural mortality, so calculated, was 31.2 percent. Assuming all nonrecovered, marked clams were dead at the termination of the experiment and if the chi-square test indicates that the number of recovered weak and injured clams of both categories (recovered and nonrecovered) agrees with the null hypothesis, which it does, then the mortality rate is found to be 30 percent. However, if all weak and injured clams were excluded, the mortality rate is found to be 25 percent.

Oearly then the death rate observed with the marked clams does not exceed that derived by Taylor's formula and is well below the 1 - k value of 34.69 percent. I, therefore, concluded that the observed mortality of marked clams was probably more a fu nction of natural causes than the result of marking and handling.

Hence, using the value obtained from Taylor's formula, the total annual mortality rates for clams at the Little Mummy Island study area could be, respectively, 0.65; 0. 79 and 0.92, where a cannot exceed unity.

The value of r obtained in the Walford graphs (Figs. 18 to 21; pp. 76 - 82) and the value of e-Mt in the preceding did not seem appropriate as estimates of rates of annual natural mortality for use in life tables, because they appeared excessively low in view of the observed age structure in the Cordova growing areas. In addition, W. P. Breese (Assoc. Prof. Fisheries, Oregon State Univ ., pers. comm., 1971) estimates that the survival rate from initial fertilization of the ova to setting is 1 in 10,000. N. Bourne (Biologist, Fish. Res. Bd. of Canada, pers. comm., 1972), however, feels that survival is more in the order of 1 in 100,000. Therefore, survival rates for individual and composite cohorts from the Cordova growing areas were calculated using the equation:

A Nt + 1 s Nt

(Ricker, 1958), where N represents the number found, of each age, in a representative sample. Survival rates listed in Table 43 appear to be accurate for razor clams in the Cordova area and have been employed in the life tables presented in Appendix 9.

Negative and Positive Relocation of Marked Razor Oams

During the collection phase of the initial study plot investigation, Orca Inlet, 1969, razor clams were encountered near the outer boundaries of some plots. A few were marked and replaced in their original locations to determine if any lateral movement into the plots occurred. Specific sites where clams were marked were Little Mummy Island (four clams) and Erickson Bar (eight clams). No marked clams had been found in any of the study plots by the termination of the collection phase.

Subsequent observations following the winter of 1969-1970 revealed that the marked clams at Little Mummy Island were alive and had not been relocated from their measured locations. Marked clams at Erickson Bar were not found. Shifting of substrate had occurred at Erickson Bar as evidenced by the obliteration of the study plot perimeters. Several of the comer posts remained, but it was not possible to tell what comers they applied to or exactly where the other comers should have been. No such disturbances were evidenced at Little Mummy Island Bar.

138 Table 43. Survival rates of razor clams in the growing area of Cordova, Alaska.

Age, years (t to t+l) Survival rate

1 to 2 0.0909 or 0.0900

2 to 3 0.3030 or 0.3000

3 to oo 0.4029 or 0.4000

139 The 35 survmng clams of the Little Mummy Island density indicator study (Survey Techniques Section) had not relocated from their known locations in the 89 days following initial transplant. All six recovered clams that had died during this period were at their original locations. The fate of the nine unrecovered clams is unknown, but they were presumed dead and were probably at a greater depth than was excavated for their recovery.

During 1971, a density indicator study was conducted at Point Steele Beach (discussed later under Survey Techniques) in which 50 marked clams were planted at known locations. Only one live clam was recovered from its original placement location after a period of 78 days. Conversely, only one dead clam was recovered from its original placement location, but time of it:; death was unknown. One live clam was recovered 96 feet (29.26 m) in the direction of prevailing tidal currents from its placement location after a period of 88 days. The fate of the remaining 47 clams is unknown. Presumably, they were either deeper than 2.5 feet (0.76 m) that was excavated at each placement location during the search for them, or they had been relocated during storms.

Young razor clams approximately I 0 mm in valve length are capable of voluntary lateral movement along the exposed beach surface and are also involuntarily relocated by uprush and backwash of the surf. Voluntary movement appears limited to short distances of about 1 or 2 feet (30 to 60 em), apparently depending on the wetness of the substrate. Involuntary dislocations by uprush and backwash have evidenced relocations of up to I 0 feet (3 m). Small clams observed tumbling in the backwash rapidly controlled their movement by gaining a 'foot-hold' and reburying themselves as the wash passed over.

Large razor clams (>60 mm) are believed incapable of voluntary lateral movement and any obvious lateral relocations are felt to result from either rapidly shifting substrates or from dislodgement by rip- or long-shore currents. By hosing seawater over razor clam-bearing substrate for a few minutes, the substrate is rendered nearly liquid, causing th e clams to float uncontrollably in the matrix where they may be easily removed. I suspect that strong tidal- or storm-generated, long-shore currents probably act in a similar way, unless the clams have buried themselves to a great depth.

As a result of the Good Friday Earthquake of 1964 the landmass in the Cordova area uplifted and massive erosion occurred, rapidly stripping surface sediment over large portions of the tidal flats and exposing several species of molluscs (Saxidomus, Pro tothaca, Sp isula, Tresus, Clinocardium, Mya, and Macoma) which perished in great numbers. In 1974, their valves were still visible at low tide. Similar evidence of a large-scale razor clam die-off following erosion of the tide flats is lacking, however. Razor clams of pre-earthquake age are still living at intertidal areas where large-scale die-offs of 'other' clam species occurred. Whether the lateral relocation of razor clams, necessary to survive the uplift, was due to erosional forces only, or voluntary vertical movement exceeding the rate of erosion, or both, is not known.

Genetics and Larval Drift

A drift drogue study was initiated August 7, 1969, to determine drift and current patterns of the growing area waters of Cordova Sectors 1, 2, 3, and 4. Drift drogues are folds of international orange plastic resembling book covers. A styrofoam float is attached to the top inside fold and each bottom comer has a small galvanized steel weight affixed to it. Folded dimension of each drogue is 11 inches by 4 inches (28 by I 0 em). The drogues, when immersed in seawater, submerge to within 1/2 inch (1.3 em) of the top fold. When subjected to wind the fold turnsinto the wind and each flap opens affording maximum resistance. Recovery information was printed on the drogues and postage on

140 each was prepaid for convenient mailing.

During a 2-day period (August 7 and 8, 1969) 350 drogues were released, one every 1/2 mile (0.8046 km) from Observation Island, at the northeast end of Orca Inlet, to the base of Okalee Spit, near Cape Suckling (Fig. 9, page 43). Recoveries by the public commenced on August 9, 1969, and continued to September 11, 1970.

Of the 56 drogues eventually recovered, 84 percent were obtained from the southeast coast of Hinchinbrook Island between Point Bentinck and Hook Point. The Hinchinbrook recoveries represented 3 percent of the 180 open-coast releases (Point Bentinck to Cape Suckling, Fig. 9, page 43) and 25 percent of the 170 Orca Inlet releases. All Hinchinbrook recoveries were made between August 9 and November 30, 1969. Other recoveries were made at Big Mummy Island and Big Point (both in Orca Inlet), Okalee Spit and Green Island (Prince William Sound). Two additional recoveries were noteworthy. One drogue was found 1 mile (1.6093 km) southwest of Perryville, Alaska Peninsula (on November 15, 1969, following a heavy southeast storm) approximately 650 miles (1 046 km) from its release point at Kanak Island; and the second was recovered from Shields Point at Perenosa Bay, Afognak Island (on September 11, 1970) approximately 293 miles (472 km) west-southwest of its release point at Strawberry Reef.

The high percentage of recoveries between Point Bentinck and Hook Point on Hinchinbrook Island and speculation concerning drift of larval razor clams led to the establishment of a study site at Point Steele Beach, laying at the center of the recovery area.

Whether the heavy set of young razor clams evidenced at the Point Steele site (and not observed elsewhere) had any relationship to the high percentage of drogue recoveries in this area (suggesting shoreward current set), to larval drift, or was purely coincidental is not known. At any rate, the larval drift theory (discussed in the following pages) and drogue recoveries led the author to a razor clam growing area of high yield. Furthermore, the drogue recovered near Perryville was less than 10 miles from the razor clam growing area of Humpback Bay, the closest razor clam bed to the villagers of Perryville (according to H. 0. Kaiakakonok of Perryville, Alaska, pers. comm.). Al so, the recovery site of the drogue at Perenosa Bay, Afognak Island, was within 20 miles of the razor clam growing area of Duck Bay, Afognak Island, the only known razor clam-bearing beach on Afognak Island.

The following discussion of genetics and larval drift, stemming from observations of several thousand razor clams and the specific habitats from which they were obtained, is purely speculative. These observations suggest, however, that certain shell charact�ristics, such as shades of periostracal pigmentation and associated streaks and blotches and identations of the valves at specific anatomical regions or seemingly at random, appear to be associated with specific growing areas on a microenvironmental scale. These differences are so apparent, in fact, that a person familiar with the various growing areas can tell, with a fair degree of accuracy, from which bars or beaches clams were collected. Whether this is an expression of genetics or merely a reflection of habitat-attitude type (see glossary), or both would be, at the least, academically interesting to detennine. Of practical value, however, may be the linking of certain measurable characteristics with discriminant functions where the probability of overlap in growth patterns may present obstacles in surveillance. On the other hand, the enormity of such an undertaking on a statewide basis would probably overshadow its worth.

I believe that the specific gravity of seawater, that is to say its degree of salinity, has a profound effect on the extent of larval drift. Prolonged warm, dry weather is thought

141 to be more conducive to drift than extensive rainy periods which would, in my opinion, allow larval forms to reside within a few hundred microns ± of the substrate surface. Friction of tidal currents along the substrate may reduce the velocities in this microenvironment sufficiently to maintain, in part, certain gene pools.

However, W. P. Breese (pers. comm., 1971), who has cultured razor clams in a laboratory from ova through the free-swimming period, states: "I do not believe that fertilized ova or the subsequent larval forms can resist tidal currents." Dr. Breese further states: "Water temperature was maintained at approximately 14° C. with the salinity as high as could be obtained. Water was changed twice a week. Aquaria used were gallon jars to 150-gallon fiber glass tanks." Dr. Breese continued by relating: "Razor clam larvae, after the first 8-10 hours of life, can remain above the substrate surface during the free-swimming larval period" ... which ... "is 30 to 40 days dependent on the temperature."

Apparently, high salinities were used by Dr. Breese throughout his experiment. A crude analogy, however, would be to swirl a weak and a concentrated brine solution, each containing a potato. The potato in the concentrated brine will float, offering little resistance to the swirling currents, whereas the one in the weak solution may, at most, spin at the bottom of the container. This is not meant to liken a potato to a razor physics involved are clam larva, hut th e th e same. Sizes of ripe unfertilized razor clam ova and larvae to age 20 days range from 89 to 256 microns, respectively, according to Dr. Breese. By referring to Hjulstrom 's diagram (Hjulstrom, 1939; In Sverdrup et al., 1954:961), which shows the relationship between average current velocity in a river and sediments of uniform texture with velocities necessary for erosion, transportation, or deposition, it can be seen that the minimum average velocities required for transporting uniform material of the above-mentioned sizes, range from approximately 0.25 to 0.75 in./sec. (0.6 to 2.0 em/sec.), whereas the maximum average velocities range from approximately 10 to 7 in./sec. (25 to 18 em/sec.), respectively. It must be borne in mind, however, that the velocities given here are the average velocities across a transverse profile of a river and that the velocity at the bottom is less. Furthermore, nothing is known about the extent to which such transportation takes place along the sea bottom (Sverdrup, et al., 1954; U.S. Army Corps of Engineers, 1966).

The maximum average velocity of surficial tidal currents during the flooding tide in Orca Inlet is 2.07 m.p.h. (92.662 em/sec.) and maximum average velocity during the ebbing tide is 1.15 m.p.h. (51.4 79 em/sec.) (Tidal Current Tables, Pacific Coast of North America and Asia, 1971). We can roughly determine bottom velocities by the following method based on work done in confined freshwater channels having streamlined flows:

(1) The surface velocity is about 9/10 of the mean. (2) The mean velocity occurs about 6/10 of way from the bottom. (3) The skin velocity (due to a drag surface, i.e., the bottom) is about 1/4 of the mean. Based on the above, the maximum average bottom velocities in Orca Inlet during the flood and ebb tides would be approximately 10 in./sec. and 5.5 in./sec. (26 em/sec. and 14 em/sec.), respectively. However, the bottom of certain areas is very rough due to eddying and bottom velocities in eddies would probably be much lower. At any rate, from these approximate figures the possibility seems to exist that there may be certain niches where tidal currents are of sufficiently slow velocity that gene pools may become established.

142 Ford (1964) has done extensive work on polygenic factors evolving in isolation, especially as pertains to selection for spotting in the Satyrine butterfly, Maniola jurtina. Ford required a character that could be studied quantitatively in this species in order to compare populations and to detect changes in them. For that purpose he chose the number of spots on the underside of the hind wings and classified them by "first-order" differences, that is modal frequencies, and "second-order" arrangements. In the course of his studies, he found that there occurred a readjustment from one stabilized spot distribution to another, caused by ecological changes of specific types. These studies have shown that extremely powerful selection pressures are operating in nature.

To summarize, it may be possible to conclusively separate individuals of geographically distinct breeding populations by "first-order" differences and "second-order" arrangements of periostracal pigmentation, etc.

143 SURVEY TECHNIQUES

Density Indicators

For as many years as man has been involved with the razor clam he has probably wondered why, when he digs clams on one day, there appear to be more or less clams available to capture than on another day. Gradually, I suppose after repeated observations of this phenomenon on the same bed of clams, the expression was coined, "the clams were showing good today" or "that was a very poor clam show" or similar variations. A few old-time clam diggers in the Cordova area were said to have had a knowledge of whether or not the 'clam show' was going to be good or bad without venturing out to the bars, but this knowledge was either synonymous with lucky guesses or retained in ones' head, the secret remaining inviolate. By ruminating over the phenomenon of 'show' and wishing to define it in quantifiable terms, I listed all of the variables that appeared to be linked with clam 'show' which I could measure in some way. It appeared to me that, armed with a knowledge of these variables, new insight could be gained into population estimation of razcr clams. It was also recognized that this species displayed what appeared to be a defmite natural orderly arrangement in frequency of occurrence by tide level on the low tide terrace. I felt that by tying these two factors together with a simple sampling scheme a rapid method of accurately censusing razor clam stocks could be developed. The following account deals with this investigation to determine density indicators from an assortment of hydrological and meteorological variables and their relationship to 'true' abundance.

The Little Mummy Island Study

On June 17, 1970, 50 stakes numbered 1 to 50 were placed within the perimeter of the study plot located at the +3 foot (+0.91 m) tide level at Study Site 2, Little Mummy Island (Plates 19 and 20). All razor clams had been removed from this plot during 1969, and subsequent observations prior to emplacement of the stakes confirmed that no clams remained. The stakes were arranged in numerical order in two rows. The upper row was located 2.5 feet (0.76 m) in from the upper perimeter of the plot and the lower row was located the same distance in from the lower perimeter, leaving a space of 5 fe et (1.52 m) between the rows. Within each row the stakes were placed 3.5 feet (1.07 m) apart.

On the same day, 66 razor clams were dug then placed in a burlap sack which was fastened to a stake at the +I foot ( +0.30 m) tide level as the incoming tide prevented fu rther work. The following day, June 18, the clams were examined as to their condition and 50 were marked with numbers 1 to 50. Marking was done with a 'DREMEL Model 2 Moto-Tool' powered by a 'TRIPP LITE' power converter which was connected to a 12-volt automobile battery. Each clam was marked on the left valve and all were in seemingly good condition.

The clams were placed 2 feet (0.61 m) se�ward from their correspondingly marked stakes and positioned in holes dug for them so that the hinge or dorsal surface faced seaward. A period of 10 days was allowed for the clams to recover from their handling and relocation prior to observing their 'shows' and collecting data thought to be related to 'showing.'

Observations began June 29, 1970, and ended September 14, 1970. During this period 28 observations were made. At each observation I remained outside the perimeter of the plot and recorded the 'show' values of each clam. 'Show' values were rated at "0",

"1 " , or "2": designating "no show"; "slight show (small dimple)"; and "very apparent

144 Pla te 19. Nu mbered stakes at the +3 fo ot (+0. 91 m) tide level, Little Mummy Island Bar, used to locate marked razor clams fo r the density indicator study.

145 Pla te 20. The complete set of 50 numbered stakes fo r the Little Mummy Island density indicator study. The City of Cordova is barely visible at the upper righ t. The view is lo oking northeast up Orca Inlet.

146 show (clear siphon hole)", respectively. Each set of observations was double-checked. Following these observations, values of 1 7 of the 18 preselected variables (Table 44) were recorded on mimeographed forms at the site location. Value of the 18th variable, specific gravity of seawater, was recorded in the laboratory.

Specific gravity of seawater was measured with a 'KIMAX' 50 ml, 20° C. pycnometer and an 'OHAUS' scale ; relative humidity was derived from a 'BACHARACH' sling psychrometer; and barometric pressure was obtained from an 'AIRGUIDE' barometer. A 'TAYLOR' mercury thermometer was employed for the various temperature recordings; wind direction was derived from compass readings; wind speed and sky cover were estimated; and the other variables were evaluated from general observations.

Meteorological observations made at Little Mummy Island corresponded closely to the Federal Aviation Agency (F.A.A.) data recorded at Mile 13 (13 mi. or 20.92 km east of Cordova, Fig. 9, page 43) on the Copper River Flats. Since data from both locations were in agreement and the data at Mile 13 were recorded by highly sophisticated instruments, the meteorological data from the F.A.A. station were used in the analysis. At the termination of the experiment I collected the surviving specimens. Of the 50 clams originally planted, 35 survived, 6 were known to have died, and the remaining 9 were presumed dead but not recovered. Thus, the analysis was based on 28 observations of 3 5 clams. The survivors consisted of 10 females and 25 males. An individual summary of these specimens is given in Table 45.

Several stepwise regression programs were run on the data using a computer. It was believed that relative humidity, barometric pressure, specific gravity of seawater, and wind direction would probably rank as the four most important variables. In the first six runs the dependent variable changed six times, that is: (1) male x show; (2) female x show; (3) male + female x show; (4) male percent show; (5) female percent show; and (6) male plus female percent show. In runs 4, 5, and 6 the original dependent variable was transformed by an arcsin square root transformation. None of the six runs produced very high correlations, i.e., the highest was approximately 0.4. In the seventh run, all of the independent variables were considered for which there was a complete set of 28 observations. In addition to the four variables given above, this run included sand temperature, low tide height, level of tide during period of observation, water surface, tide attitude, and rain. Here again, an arcsin square root transformation was made on the original dependent variable. The correlation for this case was considerably higher, i.e., around 0. 7 5. Next, all observations were eliminated for which some of the independent variables were missing. This produced a total of 21 observations instead of the original 28, and additional variables to the 10 listed above were air temperature, seawater temperature, total sky cover, total opaque sky cover, wind velocity, and sunshine on plot. Again, the dependent variable, total percent show, i.e., the percentage of clams showing on the ith visit, or in symbols,

N1'-· * 100 35

where Ni is the number of shows observed on the ith visit, was transformed by an arcsin square root transformation.

From this output, water surface, tide attitude, level of tide during period of observation, low tide height, and seawater temperature appeared to be the fivemost important variables. When all five of these were included in the regression, a correlation of 0.82 was obtained.

147 Table 44. Variables and codes that were recorded along with "show" values of marked razor clams at Little Mummy Island, Cordova Sector 1.

Variable Code

(1) Date As indicated

(2) Low tide time As indicated

(3) Low tide height As indicated (4) Level of tide during the period of observation As indicated

(5) Tide attitude 1 (ebb); 2 (slack); 3 (flood)

(6) Specific gravity As indicated

(7) Relative humidity As indicated

(8) Barometric pressure As indicated (9) Total sky cover 0 (clear); 1 to 5 (scattered); 6 to 9 (broken); 10 (overcast)

(10) Total opaque sky cover 0 to 1 0 as estimated

(11) Sunshine on plot 1 (yes); 2 (no)

(12) Rain on plot (yes); 2 (no)

(13) Water surface 1 (calm); 2 (rippled); 3 (slight chop); 4 (heavy chop)

(14) Water temperature oFahrenheit as indicated

(15) Sand temperature °Fahrenheit as indicated

(16) Air temperature °Fahrenheit as indicated

(17) Wind direction 00 to 36 in relation to true North

(18) Wind speed Knots as indicated

148 Table 45. An individual summary of the 35 surviving razor clams that were observed at Little Mummy Island, Cordova Sector 1, from June 29 to September 15, 1970, for determination of density indicators.

Average Terminal Recovery show length Age depth at Show value Oam value (mm) (nth year termin s at terminus 1 y (9/14&15)l/ Numbers Sex 6/29-9/1 5 9/1 4& 1 5 of life) CCm) 1 M 1.00 144 8 24.13 2 2 F 1.93 152 9 19.05 2 3 F 0.96 142 8 17.78 2 4 M 1.46 144 8 17.78 2 8 F 0.45 142 7 24.13 0 9 M 1.57 128 8 16.51 2 11 M 0.82 132 7 25.40 2 12 M 0.86 130 6 22.86 1 14 M 1.00 129 8 15.24 2 15 M 0.86 136 7 30.48 1 16 M 1.21 137 7 12.70 2 17 M 0.89 133 7 11.43 2 21 F 1.71 144 7 17.78 2 22 M 0.97 120 7 21.59 0 23 F 0.82 133 7 20.32 2 24 M 1.36 133 8 16.51 2 25 F 0.76 126 6 17.78 0 27 M 1.28 122 7 17.78 2 28 F 1.64 126 6 20.32 2 30 M 1.03 117 6 17.78 0 32 F 1.50 115 6 11.43 2 33 M 0.79 126 6 16.51 0 34 M 1.04 117 6 21.59 1 35 M 0.93 125 7 25.40 2 36 M 1.54 131 8 25.40 2 40 M 1.25 116 5 26.67 2 41 M 0.96 130 7 24. 13 1 42 M 1.04 116 6 21.59 2 43 F 1.25 120 6 16.51 2 44 M 0.57 120 6 17.78 1 45 M 1.29 126 6 25.40 2 46 M 1.14 121 5 22.86 2 47 M 0.82 114 6 19.05 1 48 F 1.43 125 7 21.59 2 50 M 1.04 116 5 15.24 2

X = 128.23 X = 6.74 X = 19.96 C5 = 9.91 C5 = 0.98 C5 = 4.47

1/ Depth was from the surface to the posterior edge of the valves. 2/ Show values are indicated by: 0 = no show; 1 - slight show, small dimple; and 2 = very apparent show, clear siphon hole.

149 Of course, the more variables which are included, the higher the correlation, thus further variables were not included in the regression as there were only 21 observations.

I then decided to use mean show as the dependent variable in further runs because percent show did not take into account the individual show values. That is to say, a total percent show value of 100 percent could be given to the clams whether a faint dimple or a clear siphon hole was evidenced, whereas if all shows were faint (i.e., difficult to see) the mean show value would portray this and would, it was felt, have more meaning to other investigators. Mean show, therefore, is defined as the mean of the show values observed on the ith visit to the site. In symbols this would be:

35 1: Xij j=l 35 where Xij is the show value of the jth clam on the ith visit. Also, the author felt that greater precision could, perhaps, be obtained by lagging or advancing certain independent variables in time, relative to periods of observation. At an intuitive level, atmospheric pressure at sea level still seemed to be related in some way to clam show. Therefore, a cubic regression analysis of razor clam show data and atmospheric pressures at sea level lagged from two days in the past to two days in the future relative to observations, was performed. There was no evidence of any relationship of clam show with any of the lead or lagged relative pres:• ures except, perhaps, relative pressure of the day before, and that relationship appeared to be nonlinear. This regression "explained" only 38 percent of the natural variation L1 clam show, that is, a correlation of 0.617 was obtained, thus having very little predictive value. When the clam shows were divided into four equal groups with respect to the preceding days' relative atmospheric pressure, an analysis of variance showed that the four means were not significantly different.

In an attempt to find a better relationship, the first and second derivatives of relative atmospheric pressure on the day clam show was observed,and the average preceding relative pressure were calculated, but these variableswere not strongly related to clam show. Several nonlinear mathematical models were tried, to no avail.

Finally, a stepwise regression program was run on 21 independent variables (Table 46) of which the five most important (as mentioned previously) from the initial programs were included. Other variables were those of the same day as the observation and of the day before the observation was made. Four of these variables had not been recorded as part of the routine data collection. They were water vapor deficits and mixing coefficients of the same day and the day before, respectively. These last two sets of variables were stumbled upon quite by accident while the Computer Applications Analyst was attempting to derive relative humidity values from dew points. A short summary of their calculation follows:

At a given temperature, there corresponds a maximum water vapor pressure, em. The ratio of the actual water vapor pressure, ea, to em, or ea/em is the (actual) relative humidity. The difference em-ea is called the water vapor deficit, and is supposed to be important biologically since it is directly related to evaporation (i.e., the higher the deficit, the faster evaporation takes place). Both ea and em are in millibars. The mixing coefficient is defined by:

1 50 Table 46. Variables entered into a computer for a stepwise regression analysis to determine razor clam density indicators relative to periods of observation.

Standard Variable Mean Deviation

1. Water vapor deficit, day before 3.00760 1.50897 2. Water vapor deficit, same day 3.34008 2.45957 3. Relative humidity, day before 0.78388 0.09041 4. Relative humidity, same day 0.77949 0. 10929 5. Mixing coefficient, day before 0.00653 0.00071 6. Mixing coefficient, same day 0.00673 0.00092 7. Air temperature, day before 52.53571 3.42628 8. Air temperature, same day 53.57143 5.22408 9. Dew point temperature, day before 45.71428 2.96719 10. Dew point temperature, same day 46.46428 3.64622 11. Atmospheric pressure @ sea level, day before 101 2.46265 5.60623 12. Atmospheric pressure @ sea level, same day 1012.46973 5.82319 13. Mean clam show - value 1. 1 1714 0.36720 14. Sea water temperature, same day 52.22321 1.75243 15. Low tide height, same day --0.82857 1.34491 16. Level of tide during period of observation 0.23393 1.20462 17. Water surface value 1. 96428 0.63725 18. Tide attitude value 2.25000 0.92796 19. Wind speed, day before 2.64286 3. 18810 20. Total opaque sky cover, day before 8.35714 2.81812 21. Wind speed, same day 2.96428 3.90139 22. Total opaque sky cover, same day 8.35714 3.08 178

151 .622 ea m = (P-ea) where P = atmospheric pressure in millibars. The mixing coefficient, then, is just the ratio of the mass of water vapor to the mass of dry air.

A table of maximum water vapor pressures in air (units = em. Hg) versus temperature in degrees Centigrade was used to convert actual temperatures and dew points to water vapor deficit values. A third degree polynomial was used to give values not in the table, and to convert the units to millibars (Table 47).

From the input of the data in Table 46 the combination finally settled on includes nine variables. They were:

Water vapor deficit (Same day and day before) Air temperature (Same day and day before) Atmospheric pressure at sea level (Same day and day before) Low tide height (Same day as observation) Water surface (Same day as observation) Wind speed (Same day as observation)

The basis for eliminating other variables from further consideration is that at each step in the stepwise regression, one variable is added to the regression equation. The variable added is the one which makes the greatest reduction in the error sum of squares (Reference: Biomedical Computer Programs, W. J. Dixon, U. of Cal. Press, 1971; Name of program : B.M.D. 02-R, Stepwise Regression).

The multiple correlation coefficient is .897, with 80.5 percent of the variation explained. The standard error of estimate is .199. The regression is highly significant at P<.005 (F = 8.261; critical value at .005 for 9 and 18 degrees of freedom = 4.663 ). Moreover, the reader can be about 75 percent confident that all the regression coefficientsare different from zero. The coefficient which is most doubtful is that for air temperature on the day of the measurement. Its "t" value is (.0463 - 0.)/.0 192 = 2.4 1 which is significantly different from zero at P <.025. The 75 percent value mentioned above is conservative, and is arrived at using a critical "t" value at P::::::.O 15, since there are 9 separate two-tailed tests to be done, and 9 x 2 x .015:::::: .25. The number of degrees of freedom for these tests is 19 (i.e., 28 - 9). An analysis of variance of the selected variables, the regression, and the formula for converting expected mean show to the percent clams that were showing at the period of observation are given in Table 48. These regression equations will play an important role in the newly devised method for population estimation covered later in Methods of Estimating Population Size.

In simple terms, this regression tells us that clam show is highest on wet (low water vapor deficit), warm days with low atmospheric pressure, with high low tide heights, small water surface ranks, and low wind speeds. But this is not all. Oam show is more likely to be high when a wet, warm day with low atmospheric pressure follows a dry, cool day with high atmospheric pressure.

Table 49 illustrates how clam show is affected when one of the variables is increased by one standard deviation. The included variables are ranked in order of importance according to their relationship to clam show. The four most important variables are water

152 Table 47. Conversion table for maximum water vapor pressures in millibars from temperatures 4f f in Fahrenheit used to obtain the water vapor deficit. JJ ]} lJ 'iJ !i Water Water Water Temperature vapor Temperature vapor Temperature vapor degrees pressure degrees pressure degrees pressure Fahrenheit millibars Fahrenheit millibars Fahrenheit millibars

32 6.023 55 14.683 78 32.456 33 6.301 56 15.218 79 33.539 34 6.584 57 15.77 1 80 34.652 35 6.872 58 16.342 81 35.796 36 7. 167 59 16.932 82 36.971 37 7.468 60 17.541 83 38. 179 38 7.777 61 18. 171 84 39.419 39 8.094 62 18.821 85 40.692 40 8.419 63 19.491 86 41.999 41 8.753 64 20. 184 87 43.340 42 9.097 65 20.899 88 44.7 16 43 9.45 1 66 21.636 89 46.127 44 9.815 67 22.397 90 47.574 45 10.191 68 23. 181 91 49.058 46 10.578 69 23.990 92 50.578 47 10.978 70 24. 824 93 52.136 48 11.390 71 25.683 94 53.732 49 11.816 72 26.568 95 55.367 50 12.256 73 27.480 96 57.041 51 12.710 74 28.419 97 58.754 52 13.180 75 29.385 98 60.508 53 13.665 76 30.380 99 62.303 54 14.166 77 31.403 100 64. 139

11 Relative humidity = i.e., actual water vapor pressure divided by maximum water vapor pressure. To find the actual water vapor pressure use the value opposite the dew point temperature. J:/ To find the maximum water vapor pressure use the value opposite the air temperature. ]_! The water vapor deficit e _ e jj = m a. The mixing coefficient is defined by: m = whe�e P = atmospheric Jj pressure at sea level in millibars.

!if Formu la used: F = temperature in °Fahrenheit C = (5f9)(F-32) = oCentigrade Maximum vapor pressure in millibars 2 3 = (l0l3.2f76)(0.45 182 + 0.03715C + 0.00056C + 0.00004C )

153 Table 48. Calculations using mean show as an indicator of clam density: (a) analysis of variance of the nine variables selected from the stepwise regression for determining expected mean show; (b) the regression of razor clam density indicators to determine expected mean show; and (c) the regression to convert expected mean show to the percent of razor clams showing.

(a) Analysis of Variance

Source of Degrees of Sum of Mean Variation Freedom Squares Square

Regression 9 2.931 0.326 Residual 18 0.710 0.039

F ratio = 8.261 >F.995 (9,18) = 4.663

(b) The regression to determine the expected mean show is:

Expected Standard mean show -10.39327 Error + 0. 15290 [water vapor deficit yesterday] 0.04065 -- 0. 11681 [water vapor deficit today ] 0.03579 - 0.08250 [air temperature yesterday] 0.02124 + 0.04630 [air temperature today] 0.0 1921 + 0.03530 [atmospheric pressure @ sea level yesterday] 0.00836 - 0.02153 [atmospheric pressure @ sea level today] 0.00805 + 0. 11178 [low tide height today] 0.03219 - 0.23583 [water surface today] 0.06283 -- 0. 0288 1 [wind speed today] 0.01028 Multiple correlation coefficient = 0.8973

Standard error of estimate = 0. 1986

(c) The regression to convert expected mean show to the percent of razor clams that were showing is: 2 3 Y = 0.80304723 + 71.59731827 x + 0.68185597 x - 6.99670169 x where Y = percent of clams that were showing and X = expected mean show.

Index of correlation = 0.9675

Standard error of estimate = 4.9417 percent.

154 Table 49. How clam show is affected when one of the included variables is increased by one standard deviation and the ranked importance of the variables.

Change in show when variable is increased by Day in Relation to one standard Clam Observation Variable deviation Importance

Yesterday Water vapor deficit +.230 4

Today Water vapor deficit --.287

Yesterday Air temperature --.282 2

Today Air temperature +.242 3

Yesterday Atmospheric pressure +. 198 5

Today Atmospheric pressure --.125 8

Today Low tide height +. 150 6.5

Today Water surface --. 150 6.5

Today Wind speed --.112 9

155 vapor deficits, air temperatures and their trends.

The author feels that it is extremely doubtful that the multiple regression equation relating expected mean show to environmental factors could produce a mean show value of less than 0 or greater than 2. In addition, the regression relating expected mean show to percent of clams showing will not produce estimates of percent clams showing that will exceed I 00 percent. For example, a perfect show condition, if that is possible, would yield an expected mean show value of 2, which converts to 90.75 percent clams showing. Conversely, extremely poor show conditions would produce an expected mean show value of 0 which converts to 0.8 percent clams showing.

The Point Steele Beach Study

This study was undertaken to test results of the Little Mummy Island study and determine if other variables such as breaker strength and rip currents had a measurable influence on clam show. The reader will recall that relatively stable beach conditions were encountered at the Little Mummy Island site in Orca Inlet, where breakers and rip currents are absent.

On June 5, 1971, T set 50 stilhs, nllmhArerl 1 to <:;O ilt thP- +i fo ot (+0 Q1 m) tirlt> level on Point Steele Beach (Plate 21 ); the stakes were spaced 4 feet (1.22 m) apart. A few days later, the small squares of plywood bearing the numbers were removed from the stakes as the surf had caused a trough to form up-slope from the line of stakes. In place of the numbered squares, bright flagging was fastened to every fifth stake. When this was done, the trough filled in and did not form again. On June 8, 50 clams were collected, measured, marked from 1 to 50, and then planted 2 feet (0.61 m) seaward from corresponding stakes with their dorsal surfaces facing seaward. These clams ranged in valve length from 65 to 127 mm, having a mean and standard deviation of 93.91 ± 14.90 mm, respectively.

On June 9, clam #44 was found approximately 150 feet (46 m) seaward of the line of stakes and returned to its planted location. Show values were monitored regularly from June 10 to July 19, 1971, then intermittently due to frequent storms. The experiment was terminated on August 25 because of prevailing poor weather conditions. On this date, however, only specimen #1 could be found; it was recovered at its planted location. A subsequent search on September 4 resulted in finding of specimen #22 which had been relocated 96 feet (29.3 m) from its planted location and in the direction of prevailing tidal currents. On October 4, the original placement location of each clam was excavated to a depth of 2.5 feet (0.76 m). Only the valves of #44 were found, and they were in the same location where the live specimen had been replanted.

Nonrecovery of the remaining 47 marked clams was attributed to several intense storms that occurred during late July and August. When the site was visited on August 25, the study area was heavily pocked with deep current ripples (Plate 22). A recording thermograph that had been anchored in Jhe sand at mean lower low water could not be found. Similarly, a recording thermograph located at the -1 foot (-0.30 m) tide level at Katalla Beach, Cordova Sector 4, was searched for on the same date and not found.

Unfortunately, the data collected in regard to clam show and density indicators were valueless. Until the last good reading, conducted July 19, it was unknown how many or which of the clams were dead or missing. The study was of value, however, in relation to beach movement and relocation of marked clams. It was also a useful reference study pointing out the very real difficulties that may be encountered in estimating population

I 56 Plate 21. The Poin t Steele Beach density indicator study site with 50 numbered stakes was subsequen tly obliterated by tidal currents.

157 Pla te 22. Current ripples at the Poin t Steele Beach study site were evidenced fo llo wing storms.

158 size through mark and recapture methods.

Methods of Estimating Clam Numbers

In this section, four methods of estimating the size of razor clam populations will be discussed. They are, in order of presentation: (1) employment of density indicators and probability distributions on the low tide terrace; (2) stratified random sampling; (3) computations of probabilities and reapportionment; and ( 4) mark and recapture. The first method is useful for obtaining estimates of numbers of clams 90 mm or larger which, in the Cordova area, conespond to clams that are generally 5 years of age and older. The second method is of value for obtaining estimates of clams 35 mm or smaller when substrate is screened. The third method may be used to replace the second when insufficient time and/or unfavorable tides do not permit its use, but confidence intervals will be unrealistically low. The fourth method does not appear to have practical value in the Cordova area for reasons which will be discussed. In regard to those clams between 35 and 90 mm in valve length, corresponding generally to 3- and 4-year-olds in the Cordova area, a combination of digging and screening is advocated. However, since clams within this size range generally do not have readily apparent 'shows', but have the ability in wet substrate to escape capture, sampling must be confined to the upper, well-drained tide levels and the method outlined in Appendix 4 is recommended.

Employment of Density Indicators and Probability Distributions

The significant relationships of frequency of occurrence of clams by tide level and age and length by tide level were discussed in the section Population Dynamics and Habitat Relationships. In the section on 'Density Indicators' nine significant variables were found to explain "clam show" and pertinent regression equations were advanced for use in obtaining population estimates. By combining these measurable indicators of observed behavioral characteristics, a basically sound rationale can be established for application to censusing razor clam stocks.

By referring to Table 31, page 117, it may be seen that the relative density expressed in proportion (column 3) can be employed as an empirical probability density function for the study areas of Cordova Sectors 1 and 4. It is shown by analysis of covariance (Tables 29 and 30, pp. 115 and 116) that a single regression line could be used for all of these observations. The likelihood of similar frequency of occurrence by tide level distributions in other areas seems to be a reasonable and valid assumption. Limited data furnished by other authors (Hirschhorn, 1962; Tegelberg, 1964; and Bourne, 1969) tend to support this contention, though these investigators apparently did not recognize a distinct stratification by tide level. I have found that frequency by tide level of Pro to thaca staminea and Sax idomus giganteus (little-neck and butter clams, respectively) in study areas of Prince William Sound is in the form of a negative binomial distribution on the low tide tenace. H. Feder (Associate Professor of Zoology and Marine Sciences, U. of Alaska, pers. comm.) found a similar distribution of Pro to thaca elsewhere in Prince William Sound. Adherence, then, to a natural, orderly arrangement by tide level appears to conform with some natural law, at least for the above-mentioned species in the respective locations. Thus, for razor clams, where n clams are relocated to a new position on the beach, n others, it is assumed from elsewhere on the beach, are similarly relocated by the elements to reside in the former occupants' relative position, thereby retaining this orderly arrangement.

Bourne (1969: 1-4) describing conditions at Masset, British Columbia, stated: "The number

159 of clams producing shows at any one time depends on several factors, among them the state of the tide and the weather. It would be necessary to dig all the sand in a plot to a depth of 0.5 to I m to catch most of the clams." I requested N. Bourne and D. B. Quayle (Fisheries Scientists, Fisheries Research Board of Canada, Nanaimo, B. C.) to comment on the multiple regression of density indicators. Their comments (pers. comm.) were: "At Masset, frequently razor clams are quite deep in the sand and hard to dig. Diggers claim this means the winds will blow out of the west, causing a lot of surf and swells. It also means the pressure will be high and generally sunny weather. This phenomenon would seem to fit in with your theory quite well."

In a statistical sense, then, the empirical probability density function parameters for razor clams presented in Table 31 apply only to the locations from which they were derived and investigators in other areas must determine the probability density function parameters in their particular region of study. Similarly, the multiple regression of density indicators (Table 48, p. 154) is statistically valid only for the Cordova area for the period June 15 to September 15 and investigators in other areas would have to test the included variables for application to their region of study.

As an indication of the variability of razor clam show, Table 50 presents a summary of observed and calculated numbers of clams from the Little Mummy Island density indicator study. Oam show was given a value of 0 if there was no show; a value of 1 was given if a slight dimple was evidenced; and a value of 2 was given if a very apparent siphon hole was evidenced. Shows with values of 1 are detectable usually after a moderate amount of experience in the field and while the numbers in column 3 of Table 50 may seem fairly high, an inexperienced person would probably conclude with the numbers given in column 4, which are the values of a 2 value show; that is, the latter are easily detectable by an inexperienced person.

In order to employ this method, an index tide level is selected on the low tide terrace within the habitable range of the clams. The index tide level should be located in the upper reaches of the habitable zone to allow the substrate to drain for ease of capture during sampling periods coinciding with low hold-up or minus tides, and to allow comparatively more time for sampling than would be evidenced at lower tide levels. I suggest that the 0 (mean lower low water), + 1 foot ( +0.30 m), or +2 foot ( +0.61 m) tide level contours be chosen for the index in the Cordova area.

Sampling for a population estimate of razor clams residing at Big Point Bar, Orca Inlet, was conducted on August 24, 1971. The upper habitable tide level at this bar, due to its height, is the +4 foot (+1.22 m) tide level; that is to say, the top of this bar is 4 feet (1.22 m) above mean lower low water. The +2 foot (+0.6 1 m) tide level was selected as the index tide level; contours were located with hand level, leveling rod, and measuring tape. Fifteen transects, 50 feet (15.24 m) long and 150 feet (45.72 m) apart, were established along the contour of the index tide level. Within each transect a 5 sq. ft. (0.46 m2) sampling frame was placed on the substrate five times approximately 8 feet (2.44 m) apart, or every four steps, and all razor clams that were showin were captured. Thus, in a total distance of 2,851 feet (869 m), 375 sq. ft. (34.84 m � ) were sampled yielding a total of 20 clams as shown in the raw data (Table 51). The basic data are as follows:

160 Table 50. Comparison of observed and calculated number of razor clams with reference to the known location of 35 marked specimens from the Little Mummy Island study, Cordova, Alaska.

(I) (2) (3) (4) (5) (6) (7) (8) (9)

1 1.54 30 24 1.4545 84.85 35.35 33.55-38.49 33.41-37.54 2 1.60 32 24 1.3661 82.05 39.00 36.49-43.13 36.79-41.50 3 1.43 32 18 1.5620 87.64 36.51 35.25-39.05 34.57-38.69 4 1.11 28 11 1.1948 75.39 37. 14 33.75-42.50 34.86-39.74 5 1.29 25 19 1.2012 75.66 33.04 30.06-37.75 31.02-35.35 6 0.88 20 II 0.8090 55.47 36.06 30.08-43.17 33.11 -39.58 7 0.26 7 2 0.5709 40.60 17.24 13. 18-25.74 15.37-19.63 8 1.34 28 18 1.0859 70.40 39. 77 35.41-46.68 37.1 7-42.77 9 1.34 29 18 1.2375 77. 19 37.57 34.40-42.60 35.31-40.14 10 0.37 10 3 0.3588 26.26 38.08 25. 18-81.56 32.05-46.90 II 1.17 31 10 1.3879 82.78 37.45 35. 16-41 .25 35.34-39.83 12 1.31 26 20 1.2321 76.97 33.78 30.90-38.35 31.74-36.10 13 0.91 21 II 1.3223 80.49 26.09 24.23-29.09 24.58-27.80 14 0.46 10 6 0.4520 32.66 30.62 21.86-52.98 26.60-36.08 15 1.20 27 15 1.0140 66.81 40.41 35.46-48.35 37.63-43.64 16 0.66 17 6 0.7554 52.26 32.53 26.71-42.85 29.72-35.93 17 1.14 23 16 1.0929 70.73 32.52 28.99-38.10 30.40-34.96 18 1.03 23 13 0.9608 69.34 33.17 31.15-43.67 30.96-35.71 19 1.51 31 22 1.4732 85.39 36.30 34.55-39.40 34.32-38.53 20 1.09 24 14 1.1441 73.13 32.82 29.55-37.98 30.74-35.20 21 1.23 28 14 1.2784 78.83 35.52 32.75-39.94 33.43-37.89 22 1.54 29 25 1.4276 84.05 34.50 32.60-37.74 32.59-36.66 23 1.00 21 14 0. 7118 49.59 42.35 34.27-57.10 38.51-47.03 24 0.74 18 8 0.8738 59.22 30.40 25.81-38.05 28.06-33.16 25 0.80 21 7 0.9768 64.87 32.37 28. 17-39.15 30.08-35.04 26 1.46 31 20 1.3830 82.62 37.52 35.20-41.37 35.40-39.91 27 1.40 28 21 1.4650 85. 16 32.88 31.25-35.73 31.08-34.90 28 1.46 28 22 1.4886 85.82 32.63 31.13-35.32 30.85-34.62

Explanation of the numbered columns:

(I) Observation. (2) Actual mean show. (3) Observed number of all shows. ( 4) Observed number of 2 value shows. (5) Calculated mean show utilizing the multiple regression of density indicators. (6) Calculated percent clams that were showing utilizing the conversion equation. (7) Estimated mean number of clams; i.e., (7) = (3) (6) (8) Range of the standard error of the multiple regression; estimated number of clams. (9) Range of the standard error of the conversion equation as pertains to the estimated mean number of clams (column 7).

161 Table 51. Raw data from field notes for a population estimate of dug razor clams at Big Point Bar, Cordova, Alaska, 197 1.

Number of clams per sampling frame (0.4645 m2)

Transect Frame Frame Frame Frame Frame Total number Number #1 #2 #3 #4 #5 of clams 0 0 0 1 2

2 0 0 0 0 0 0

3 0 0 1 0 0

4 0 0 2 0 0 2

5 I 0 0 0 0

6 0 0 0 0 0 0

7 0 0 0 0 0 0

8 0 I I 0 0 2

9 0 0 0 0 0 0

10 I I 2 0 0 4

11 0 0 1 0 1 2 12 0 0 0 0

13 0 0 0 I I 2

14 I 0 0 0 2 3

15 0 0 0 0 0 0

Sum = 20 Estimated

Standard Standard Number of Oams Mean Deviation Error per 5 frames per transect (25 sq. ft. or 2.3225 m2) 1.3333 1.2344 0.3 187 per 1000 sq. ft. (92.9 m2) 53.3320 49.3760 12.7480 Hydrological and meteorological data were collected for August 23 and 24; that is, the day before and the same day of the sampling at morning low tide periods, then plugged into the multiple regression of denisty indicators to obtain an expected mean show value equal to:

-10.39327 +0.15290 (5.285, i.e., water vapor deficit August 23) -0.11681 (4.952, i.e., water vapor deficit August 24) -0.08250 (60, i.e., air temperature [°F.] August 23) +0.04630 (58, i.e., air temperature [op.] August 24) +0.03530 (997 .4, i.e., sea level pressure August 23) -0.02153 (1 006.1, i.e., sea level pressure August 24) +0.11 178 (+0.8, i.e., low tide height [feet] August 24) -0.23583 (2, i.e., water surface August 24) -0.02881 (03, i.e., wind speed [knots] August 24)

Theregression yields an expected mean show value of 0.64998483 ± 0.1 986 which, when plugged into the regression for converting expected mean show to the percent of clams that were actually showing, yields: 45.7070 ± approximately 12.5 percent.

From the estimates of clams that were showing, estimates of clams actually resident in the sampled area were obtained by dividing by the estimated fraction which could be expected to be showing under given hydrological and meteorological conditions, i.e.:

- - 53.3320 - 116.7002 clams per 1000 sq. ft. (92.9 m 2 ). Y 0.4S7 The variance of all subsequent calculations presented for this method in the following depends only on the variance of this estimate. Although there is no exact variance of this ratio, variance estimates will probably be adequate and may be assumed exact provided that one makes the questionable assumption that the Pi values are known exactly (i.e., not subject to error). This theory covers formulas for expected values and variances of linear combinations of random variables. For an example, see Theorem 7.2 of "Mathematical Statistics " by John Freund (Prentice Hall, 1962).

A set of probabilities derived from Table 31, p. 117, for this particular set of tide levels, that is +4 to -3 foot ( + 1.22 to -0.91 m) tide levels, is now obtained by dividing the relative density for the nth tide level from the +4 to the -3 by the sum of those respective tide levels, Thus, for the index tide level, p = 3214/43436 = 0.0740. Therefore, let: P· Probability of distribution for the ith tide level; 1 =

= Probability of distribution for the index tide level;

163 Ai = Area in m2 for the ith tide level;

v-y = Variance Y estimated by the following procedure: ( 2 N ) 2 = 2 V * y % clams showing (std. error) where N is the total number of clams captured;% clams showing is the calculated percent of clams showing in decimal form ; and std. error is the standard error of the mean derived from the raw data.

Thus, ( 40 ) 2 = 2 Vy 0.457 * (0.3 187) = 778. 1 292

Because the P(s that appear in the following expressions are assumed to be known without error, when in fact they certainly are subject to error, the associated variance expressions will produce minimum estimates (i.e., are biased low). Hence:

(1) the total estimated "true" frequency per 1000 sq. ft. (92.9 m2) is

P·1 L- * Y; where Y = 116.7002 PI (2) the total expected yield for the sampling area is

T *

(3) the variance of T is 2 (LPi Ai) 2 * v­ pl * 92.92 Y ( 4) individual tide level estimates will have variances 2 ( P·1 A· 1 ) * v- PI * 92.9 . Y Table 52 presents the population estimate of razor clams at Big Point Bar. If one is concerned about the accuracy of this esthnate, an analysis of Table 50 will reveal some interesting facts. Table 50 is an in-depth inspection of the method in that the multiple regression of density indicators and the conversion equation are tested 28 times on absolutely 35 marked clams of the Little Mummy Island study. A few calculations reveal, in regard to the multiple regression, that the true number of clams falls within one standard error in 71.42 percent of the trials; the true number of clams falls within two standard errors in 96.42 percent of the trials; and the true number of clams falls within three standard errors in 100 percent of the trials. As for the conversion equation, from which

164 Table 52. Population estimate of dug razor clams at Big Point Bar, Cordova, Alaska, 1971, utilizing probabilities and density indicators.

(1) (2) (3) (4) (5) (6) (7)

1.2192 to 3736.70 0.0041 6.4658 260.0736 62. 1657 1.1430

1.1426 2 to 7482.09 0. 0150 23.6554 1905.1903 455.3996 0.9906

0.9902 3 to 5891.82 0.0327 51.5689 3270.5545 781 .7640 0.8382

0.8378 4 to 4301.55 0.0539 85.0019 3935.8443 940.7889 0\ (..11 0.6858 0.6854 5 to 3180.54 0.0740 116.7002 3995.3676 955.0168 0.5334

0.5330 6 to 2050.84 0.0901 142.0904 3136.7560 749.7820 0.3810

0.3806 7 to 1990.01 0. 1 000 157.7030 3378.1539 807.4835 0.2286

0.2282 8 to 1920.49 0. 1037 163.5380 3380.7649 808. 1077 0.0762

0.0758 9 to 2050.84 0. 1019 160.6993 3547.5631 847.9776 -0.0762 Table 52. (continued)

(1) (2) (3) (4) (5) (6) (7)

-0.0765 10 to 2181.19 0.0959 151.2372 3550.8823 848.7710 -0.2286

-0.2289 11 to 1990.01 0.0868 136.8862 2932.2375 700.8957 -0.3810

-0.3813 12 to 1790. 14 0.0764 120.485 1 2321.6916 554.9563 -0.5334

-0.5337 13 to 1590.27 0.0655 103.2954 1768.2201 422.6595 -0.6858

-0.6861 14 to 1390.40 0.0549 86.5789 1295.7949 309.7352 -0.8382

-0.8385 15 to 538.78 0.045 1 71.1240 412.4888 98.5976 -0.9144

Sums 42085.67 1.0000 1577.0297 39091.5834 ± 2647.6022

Explanation of numbered columns: (1) Strata. (2) Tide level (meters) ± mean lower low water. (3) Area (m2). (4) Probability of distribution for the ith tide level. (5) Estimated " true" abundance per 92.9 m2 (1000 ft.2). (6) Mean estimate of the total expected number for the sampled area. (7) Standard deviation. the estimated mean number of clams (column 7) was subsequently calculated, the grand mean and standard deviation of column 7 is found to be 34.4150 ± 4.8269 clams. In regard to column 8, which is the range of one standard error of the multiple regression in numbers of clams, we find that the true number of clams is much closer to the lower estimate than to the upper estimate. That is, in 100 percent of the trials the lower range of the standard error averages 12.54 percent below the true number of clams, whereas the upper range of the standard error averages 20.11 percent above the true number of clams; such is the nature of this regression. As to the range of the standard error of the conversion equation, we find that the true number of clams falls within one standard error in 53.57 percent of the trials; the true number falls within two standard errors in 85.71 percent of the trials, within three standard errors in 92.85 percent of trials; and within five standard errors in 100 percent of trials. Therefore, bracketing of estimates can best be accomplished by utilizing the standard error of the multiple regression.

By utilizing three standard errors of the multiple regression on the Big Point data, we can be about 100 percent confident that the true number of clams falls within the range 23,043 to 378,624 clams and that the true number is closer to the lower estimate. Continuing to bracket our estimate, we can be about 96 percent confident (two standard errors) that the true number of clams falls within the range 26,083 to 94,863 clams, again assured that the true numher has a hi!!her probability of heing closer to the lower range. Furthermore, since our estimated grand mean (column 7 of Table 50) is very close to the true number of clams, and if we allow a ratio to be formed such that twice the standard deviation of the grand mean multiplied by the Big Point estimate, the product of which is divided by the grand mean estimate, i.e.:

39,091.5835 34.4150 * 9.6538 a more realistic approximation to the 95 percent confidence interval of the Big Point mean estimate is obtained, ranging from 28,126 to 50,057 clams, rather than 39,091.5835 ± 2(2,647.6022).

It may be argued that ease of comparison in a set of estimates through use of this ratio is gained at the expense of information. However, the ratio of the lower estimate standard deviation (column 8, Table 50) to the estimated mean number of clams (column 7) and to the true number of clams within the sampled area and under a diversity of environmental conditions is so nearly constant that the population standard deviation, I feel, may be assumed proportional to the grand mean and fiducial limit estimates (column 7, Table 50), hence proportional to population size (Reference: Snedecor, 1946). Estimates of age-class total are simple multiples of Y, hence their variance is the variance, Vy, multiplied by the square of the appropriate constant. Earlier, under Population Dynamics and Habitat Relationships, it was shown that age and size of razor clams are significantly greater at lower tide levels. Therefore, utilizing the regressions of age (Y = -0.2257 X + 6.7727) and length (Y = 3.4455 X + 107.1320) by tide level and by forming ratios, approximations were made of the average age and length by tide level. By utilizing the above procedures, an estimated age-density structure is realized for the Big Point area (Table 53). Lack of 4- and 5-year-old clams in the sample probably indicates that those two year-classes had poor survival success and will not contribute much to the fishery. Regression data indicate that clams older than 10 years of age would be found generally below mean lower low water; however, in order to sample for these older specimens a combination of extreme minus tides, i.e., -3 .5 feet (-1.07 m) and reasonable weather would be in order (a combination that does not occur with high frequency in the Cordova area).

167 Table 53. Estimated age - density structure of dug razor clams at Big Point Bar, Cordova, Alaska. 1971.

(1) (2) (3) (4) (5) (6)

3 0.05 5.835 199.77 1954.6 467.2100

4 0 0 0

5 0 0 0 6 0.05 5.835 199.77 1954.6 467.2100

7 0. 15 17.505 599.30 5863.8 1401.6301

8 0.50 58.350 1997.68 19546.0 4672. 1002

9 0. 15 17.505 599. 30 5863.8 1401.6301

10 0. 10 11.670 399.54 3909.2 934.4200

Sums 1.00 116.7002 3995.36 39092.0 ± 5202.6306

Approximate mean age = 8.34 years

Approximate mean length = 137.91 mm

Explanation of numbered columns:

(1) Age (nth year of life).

(2) Proportion of clams by age-class obtained during sampling. (3) Estimated "true" mean number of clams actually present along the index tide level per 92.9 m2. Column (3) = Column (2) x 116.7002.

(4) Population index; i.e., the estimated number of each age class between the +0.5334 and the +0.6854 m (+1.75 to +2.25 ft.) tide levels.

= 3180.54 x Column (3) Column (4) '92.9 (5) Mean estimate of the total expected number for the sampled area by age-class. Column (5) = 39092 x Column (2)

= (Column (5) entries)2 (6) Standard deviation. Column (6) v'! x 778.1292 116.7002

168 Hence, for estimated numbers of older age groups one must wait for favorable sampling conditions, though we can estimate the mean age and size at these tide levels as given above. Dominant year-classes, depicted by the 8-, 9- and 1 0-year-olds, should be available to the fishery for another 8 to 11 years, i.e., these clams live to be about 18 years old.

At this writing, it is unknown what effect intensive exploitation by hand, hydraulic, or mechanical diggers on the low tide terrace would have on the frequency of razor clams by tide level; hence, the probability density function parameters. Presumably, digger orientation on the low tide terrace with regard to competition, weather, and tide cycles would have a self-weighting effect. That is to say, the natural arrangement of razor clams in regard to density stratification by tide level would probably not be altered to a significant extent for a prolonged period of time. Heavy digging may tend to cause the density profile distribution to be somewhat flat-topped, but storms and annual beach cycles are expected to rearrange densities toward "normalcy" which, as I have shown, is skewed as a negative binomial. This, of course, is speculation and further studies are required to more fully understand the impacts of heavy exploitation on density profiles.

This method for estimating population size falls beyond the scope of classical statistical analysis. Due to the complexities involved by incorporating probability distribution functions, which in themselves arc estimates having d within vaiiau�_,e awl amuug a1eas, times, substrates, etc., variances as well, and a percent of clams showing value derived through two regression equations also estimated and having a variance, the population estimate, therefore, has considerable error and, with present knowledge of statistical procedures, a true variance is virtually impossible to estimate. Variances obtained in this method should be considered as approximations to the true variance.

Depending upon the degree of refinement of the variance approximations, one has the option of employing the rapid method given in the preceding, or expanding the given equations for greater accuracy as presented in Appendix 10. Critics of this method may argue that because calculation of a true variance is inestimable, only poor population estimates will result. I feel, however, that the method does yield valid estimates even though true variances are approximated; this is substantiated by earlier inspection of data in Table 50. Therefore, in my opinion, if the required number of sampling frames were placed at random and not stratified, if sampling were done with replacement, and if the same area of beach was sampled at close sequential intervals during a period when clam harvesting was curtailed, very reliable estimates could be obtained.

In growing areas having high clam population densities, this method has practical application. Once the probability density function parameters are known and the density indicator variables are tested, population estimates can be conducted rapidly by censusing upper habitable zones where lowest number of clams would occur.

To summarize, there are 10 steps in this method:

(1) Make environmental measurements at a site.

(2) Count shows and dig showing clams.

(3) Calculate "expected mean show " from multiple regression of environmental values.

(4) Calculate percent showing from "expected mean show" by cubic regression model.

169 (5) Calculate from (2) and (4) number of clams per unit of area.

(6) Determine proportions of clams at various tide levels from results of Table 31.

(7) Estimate densities at all tide levels from (5) and (6).

(8) Determine areas corresponding to tide levels.

(9) Estimate numbers at all tide levels from (7) and (8).

(1 0) Sum estimates (9) to get estimates of population on the beach being sampled.

Stratified Random Sampling

If each tide level of the Big Point Bar sampling area, described in the preceding, were sampled in the same manner as the index tide level the resultant scheme would constitute a stratified sample of the beach, with a simple random sample in each stratum. The only violation of this premise is that the seventy-five 5 sq. ft. (0.46 m2) samples were not taken randomly through the entire 2,850 linear feet (869 m) of beach. This is not a serious violation of the required assumptions, however, and can be ignored.

Thus, there were 15 strata, where the strata are by tide level. Since the samples were 5 sq. ft. (0.46 m2) in area, it is easier to work with units of 5 ft. or 1.52 m = 1 unit until the final stage. Thisme asurement unit will be termed a rod (abbreviated rd.); thus, 1 rd. = 5 ft. (1.52 m) and 25 sq. ft. (2.32 m2) = 5 rd.2, etc.

The following definitions and notations are used in the calculation:

Stratum: area surrounding transects.

h = stratum number. 2 2 Nh number of l-rd. units in stratum h (area in rd. ). 2 nh = number of l-rd. units sampled in stratum h.

Yhi = clam show (number of clams showing, i.e., captured or capturable but escaped) in stratum h, transect i.

N = total number of l-rd.2 units on beach (beach area rd.2).

wh = Nh/N = stratum weight. n h 2 y = 1 /nh 1: Yhi = stratum mean show per rd. . i= l 15 2 Yst = 1: wh Yh = beach mean show per rd. for entire beach. h= l

= the estimated variance

1 70 of clam show within stratum h. The standard deviation of clam show for stratum h is : sh = .JS2h 15 15 w 2 s 2 -1 w s 2 S2 ) = h 2: h h CYst � t1 wh N h=l where s2(yst ) is the variance of the mean clam show for the whole beach. The standard error of Yst is given by S(Yst)= V S2CYst) Estimated stratum h total clam show (clams/ft.2) or (clams/m2)

Standard error of stratum h total clam show (clams/ft.2) or (clams/m2)

Estimated beach total clam show (clams/ft.2) or (clams/m2)

= 5 NYst Standard error of beach clam show (clams/ft.2) or (clams/m2)

= 5 NSCY'st) Confidence limits for stratum total:

where t is from t table with nh-1 degrees of freedom. Confidence limits for beach total:

5N Yst ± ZNSCYst) where Z is from normal tables.

Of course, all this effort provides only an estimate of the total number of clams showing (i.e., captured or capturable at the time of sampling) for the beach - it does not give an estimate of the total number of clams that are actually residing at the beach. However, to be assured of a safer estimate of the total number of clams showing, the whole procedure should be done twice, once with high estimates and once with low estimates. The final estimate would be:

5NYst (low) + 5 NY'st (high) N average = 2

lower confidence limit = N average - 5 Z S

upper confidence limit = N average + 5 Z S

2 where S = 1/2 viS 2(Yst high) + S (y st low)

171 Obtaining the high and low estimates is, however, not a simple matter. If a regression is employed for c = clams/rd.2 in terms of observed show, f, based on a sample of n, for high and low estimates use:

regression: c = a + bf

f0 = observed clam show 2 CJow = a + bf0 - t 1 + 1 + (f0 - f) V n n 2 L: (fi - [) i=l

(1) t is from t tables, with n - 2 degrees of freedom.

(2) f is mean clam show (see regression output).

(3) n 2 2 L: (fi - 1) = (n-1) sf i=1

Where Sf is the standard error of clam show - see regression output - remember to square the Sf to get Sf2.

Chigh = a + bfo + t V 1 + 1 + (fo - f)2 n n 2 L: (fi - f) i= l

When the regression involves several independent variables, as was the case in the preceding method on probability and density indicators, the formula is much more complicated and will not be discussed. Hence, utilization of this method to estimate the total number of large clams (90 mm +) showing on the beach at the sampling period is sufficient and the confidence limits will indicate the researchers' estimate of the number of clams that were showing, not an estimate of the true number of clams.

Stratified random sampling is of value and I feel it furnishes reliable estimates of 1- and 2-year-old clams if substrate samples are screened. The number of samples (5 cu. ft. or 0.14 m3) that are physically obtainable depends upon habitat exposure, available manpower, and equipment. For the Orca Inlet study sites, which are protected from breakers, I alone was able to obtain 40 samples (40 cu. ft . or 1.13 m3), i.e., 20 samples per 1000 sq. ft. (92.9 m 2) study plot, or two tide levels per tide before the flooding tide inundated the plots. At these sites, washing substrate through the screen was facilitated by employment of a pump mounted in a skiff. On a beach exposed to breakers where use of a pump was not possible, a maximum of eight samples per tide level could be attained per tide if only two tide levels were to be sampled. This necessitated three men, one digging and two carrying buckets of water. On a breaker or a protected beach where all habitable tide levels were to be sampled (i.e., -3 , -2, -1, 0, +1, +2, +3 and +4), a maximum of three samples per tide level per tide could be attained if one man dug and three men carried buckets of water, or if one man dug and one man hosed the substrate through the screen.

The latter procedure was used on the bars in Orca Inlet as an index to clam density.

172 Three samples were taken randomly at each tide level at an index station. Index stations were initially selected at random for comparing year-class success among the various bars and subsequent sampling was confined to the same stations on a year to year basis. The proportion of the beach represented by each index station was estimated by the author; the greater the area represented, the greater the chance of error in the estimate. Therefore, in most instances, since screening occurred roughly within a 15-foot (4.57 m) wide corridor from upper to lower tide levels, this was considered to represent about 10 percent of that particular portion of the beach.

Screening at Big Point Bar, Orca Inlet, on July 9, 1971, will be used as an example of the procedure to follow in estimating the density of 1- and 2-year-old clams, though only 1-year-olds were evidenced. Raw data for the Big Point screening (Table 54) can be treated as a stratified random sample, depicted in Table 55. As shown in Table 55, the sample size for this area might have been larger. The number of samples that would be required to estimate, within 10 percent, the mean number of 1-year-old clams per rd. 2 is given by:

= 2 2 N ct ) cs ) (a y)2 where t is from the t tables with n-1 degrees of freedom, for a given significance level; s2 is the sample variance, a is the accuracy desired in describing the mean; and y is the mean number of clams in a group of n samples. Thus, at the 5 percent significance level, 536 samples are required to estimate the mean under these prescribed limits (y = M ± 10% ). Therefore, in order to obtain an equal number of samples for the Big Point sampling, 77 samples total or five samples per tide level would be required. Probabilities and Reapportionment

As stated earlier, this method can be used instead of stratified random sampling for screened estimates of 1- and 2-year-old clams, though confidence intervals will be unrealistically low. This method is of value, however, when only a limited number of strata are available ) due to time or tides. For example, n samples can be taken along one stratum and, from these data (using probability density fu nction parameters for the particular range of tide levels under study), estimates can be obtained for all strata in the sampled area.

A reasonable assumption seems to be that if few 1- or 2-year-old clams are evidenced upon screening, there are probably fe w 1- and 2-year-old clams in the general vicinity ) of the area where the screening was done, and vice versa. Furthermore, since there is no particular grouping of the clams other than a stratification of density by tide level, their distribution can be described as Poisson which, in turn, provides a close approximation to the binomial distribution since p is small (as evidenced in Table 52) and A. = 1.

Accordingly, if the raw data in Table 54 were treated such that only one or, at most, three tide levels were sampled, estimates of the entire sampled area could be made. In Table 56, I have assumed that sampling was conducted only at the 0 tide level (mean lower low water) and, as seen, only one probability density fu nction parameter (p.d.f.) has been accounted fo r. Estimated mean number of clams for the remaining tide levels is obtained by the ratio:

= 1.67 (column 3) ) y 0.1132

173 Table 54. Raw data for the Big Point Bar screening, July 9, 1971, Cordova, Alaska.

Number of 1-year-old clams per sampling frame (5 ft. 3)

Stratum Tide Level Frame Frame Frame Number feet meters #1 #2 #3 Totals

+4 +1.22 0 0 0 0

2 +3 +0.91 0 2

3 +2 +0.61 0 2 0 2

4 +1 +0.30 2 0 2 4

5 0 0.00 0 3 2 5

6 -1 --0.30 3 0 0 3

7 -2 -0.61 3 2 6

Sum = 22

174 Table 55. Estimated number of 1-year-old razor clams within a 15 0-foot ( 45.72 m) wide corridor, from upper to lower tide. levels, at Big Point Bar, July 9, 1971, using the stratified random sampling method.

2 2 wh s h 2 h N n Y w s w * w s h h hi h yh h h h ii 169.5 3 0 .19 0 0 0 0

2 267 3 2 .30 .67 .3333 .2100 .1000

3 144 3 2 .16 .67 1.3333 .2389 .2133

4 90 3 4 .10 1.33 1.3333 .0933 .1333

5 93 3 5 .10 1.67 2.3333 .1633 .2333

6 90 3 3 .10 1.00 3.0000 .2100 .3000

7 40.5 3 6 .05 2.00 1.0000 .0175 .0500

N= 894 n= 21 0.9331 1.0300

* wh = nh/n = sample weight . Yst = 0.8082 clams per rd. 2 for the entire beach (corridor). 1 1 S 2(- ) 2T (1 = Yst (0.9331) 894 .0300) 0.0433.

S CYst) 0.2080 95% confidence limit 5N hYh = and 5N hSh = h

0 0 0 2 894 771 322

3 482 831 348

4 599 520 217

5 777 710 297

6 450 779 326

7 405 203 85

5N'Yst = 3613 ± 5NS(Yst) = 930; 95% confidence interval = 365 175 Table 56. Population estimate of screened razor clams at Big Point Bar, Cordova, Alaska, July 9, 1971, using probabilities and reapportionment from samples obtained at mean lower low water.

(1) (2) (3) ( 4) (5) (6) (7)

+ 1.2192 to 0.00458 0.07 423.6 29.65 5.43 + 1.1430

+1.1426 to 0.01670 0.25 847.2 211.80 14.16 +0.9906

+0.9902 to 0.03638 0.54 667.2 360.29 18.11 +0.8382

+0.8378 to 0.05986 0.88 487.2 428.74 19.57 +0.6858

+0.6854 to 0.08222 1.21 360.0 435.60 19.70 +0.5334

+0.5330 to 0.1 0007 1.48 232.8 344.54 17.75 +0.38 10

+0.3806 to 0.11107 1.64 225.0 369.00 18.30 +0.2286

+0.2282 to 0. 11527 1.70 217.2 369.24 18.31 +0.0762

+0.0758 to 0. 11317 (m.l.l.w.) 1.67 232.2 387.77 18.72 -0.0762

--0.0765 to 0.10654 1.57 247.2 388. 10 18.72 -0.2286

--0.2289 to 0.09649 1.42 225.0 319.50 17.15 --0.3810

176 Table 56. (continued)

(1) (2) (3) ( 4) (5) (6) (7)

-0.3813 to 0.08490 1.25 202.8 253.5 15.41 --0.5334

--0.5337 to 0.07275 1.07 101.4 108.50 10.27 -0.6096

Sums 0. 11317 0.88683 4468.8 4006.23 ± 60.43

Explanation of columns:

( 1) tide level (meters).

(2) probability density fu nction parameter accounted for.

(3) p.d.f. not accounted for.

A (4) X no. clams/rd. 2

(5) area, rd. 2

(6) estimated no. clams/tide level.

(7) standard deviation, /npq.

177 which, when multiplied by the respective areas yields the estimate. This estimate indicates that the expected number of clams lies between 3,850 and 4,162 with a probability of 0.01 (60.43 times 2.576 = 155.67). However, if we had taken samples at the +2 foot ( +0.61 m) tide level the estimated number of clams for the sampled area reveals 2219 ± 115.89 at the 0.01 level of probability. Obviously, there is a large difference between these two estimates, but more important is the fact that both estimates are well within two standard errors of the stratified random sampling estimate given in Table 55. Greater precision and agreement would be evidenced with more intensive sampling.

If time and tides permitted only the 0, + 1 and +2 foot (0, +0.30 and +0.61 m) tide levels of Big Point Bar to be sampled by screening, the procedure to follow would be that given in Table 57. Here, column 4 is obtained by the ratio:

11 (column N = 3) 0.3064 which is divided by 3 (the number of samples taken per tide level) to obtain column 5. The sum of the products of columns 5 and 6 yields the population estimate, which, as seen, complements that obtained in Table 55.

Mark and Recapture

This method is not recommended for the Cordova area except on the most stable bars of which there are few due to shifting substrate and relocation of marked individuals. At any rate, perhaps the most important aspects of this type of study relate to answers to the following questions:

(1) What is the stratified frequency of occurrence profile on the low tide terrace? Determination of this profile is important in order to allocate for the planting of marked clams and for the subsequent sampling effort to obtain the marked to unmarked ratio.

(2) How stable is the growing area? A rapidly building or degrading beach is difficult to work on, to say the least. Also, a storm-washed beach can becomehighly altered and, in tum, possibly relocate marked individuals to formerly more or less productive sections.

(3) What is the source of recovery data? Highly distorted results of population estimates may occur if commercial and/or recreational catches are used as a basis for estimation unless the stratification of intensity of effort on the low tide terrace is known.

(4) What is the natural mortality rate of the studied population? Assuming marked individuals are not structurally injured by the marking process nor subjected to unnecessary stress (i.e., rough handling, over-exposure to air and sun, etc.), a reasonable estimate of this statistic can be obtained for specific age classes by planting them at known locations and subsequently monitoring their condition.

Once these basic questions are answered and their impact can be estimated with reasonable precision, the Peterson method or Chapman's adjustment to the Schnabel method may be employed. It must be remembered, however, that either method will always tend to underestimate the population due to the hydrological and meteorological variables which inherently bias the apparent abundance. If these variables are taken into account by

178 Table 57. Population estimate of screened razor clams at Big Point Bar, Cordova, Alaska, July 9, 1971, using probabilities and reapportionment from samples obtained at the 0, +0.30, and +0.61 m tide levels.

(1) (2) (3) (4) (5) (6) (7) (8)

+1.2192 to 0.00458 0. 1 644 0.0548 423.6 23.21 4.80 + 1.1430

+ 1.1 426 to 0.01670 0.5994 0. 1 998 847.2 169.28 12.67 +0.9906

+0.9902 to 0.03638 1.3058 0.4353 667.2 290.41 16.26 +0.8382 ...... -..l \0 +0.8378 to 0.05986 2. 1486 0.7162 487.2 348.93 17.65 +0.6858

+0.6854 to 0.08222 2.95 12 0.9837 360.0 354. 14 17.76 +0.5334

+0.5330 to 0.1 0007 3.5919 1.1973 232.8 278.73 15.96 +0.3810

+0.3806 to 0. 11107 3.9867 1.3289 225.0 299.00 16.48 +0.2286

+0.2282 to 0. 11527 4.1 375 1.3792 217.2 299.55 16.49 +0.0762 Table 57. (continued)

(1) (2) (3) (4) (5) (6) (7) (8)

+0.0758 to 0. 11317 4.0621 1.3540 232.2 314.41 16.85 -0,0762

-0.0765 to 0.1 0654 3.824 1 1.2747 247.2 315.11 16.87 -0.2286 .

--0.2289 to 0.09649 3.4634 1.1545 225.0 259.75 15.46 --0.3810

--0.3813 to 0.08490 3.0474 1.0158 202.8 206.00 13.89 00 0 --0.53 34

--0.5337 to 0.07275 2.6113 0.8704 101.4 88.26 9.27 --0.6096

Sums 0.30646 0.69354 4468.8 3246.78 ± 54.40

Explanation of columns:

(I) tide level (meters). (2) probability density fu nction parameter accounted for. (3) p.d. f. parameter not accountr�rt for. ( 4) estimated no. clams/3 rd.2 (ave. no. samples per tide level). (5) estimated X no. clams/rd.2 (6) area, rd.2 (7) estimated no. clams/tide level. (8) standard deviation, I npq. using the appropriate regressions advanced from the Little Mummy Island study, then more reliable estimates will be attained.

To determine the number of marked individuals and estimate the subsequent sampling effort needed to assess the marked to unmarked ratio, use the method described in Table 58.

Beach Surveys

During 1970, a survey was made of the major razor clam producing bars of Cordova Sector 1. The purpose of the survey was to delineate the bars and extent of their respective habitable zones for future reference in regard to population estimates and evolutionary changes of the bars themselves. In the past, clam industry officials sent teams of men in skiffs to locate better producing areas and sketches were made of bar outlines relative to fixed points of land. These crude sketches were designed merely to locate areas and were not done by triangulation. These old charts testify to bar evolution over the years and long-time clam diggers in the Cordova area also bear witness to these changes. Major producing bars of the past are now deep-water channels; protected areas now 4 miles from the coast were, in the late 1940's, pounded by breakers (Pierre de Ville, Carl Olson and Ed King, long-time Cordova residents and clam diggers, pers. comm.).

As noted in Plates 1 and 2 (pp. 38 and 39), the bars and channels of Cordova Sector 1 form a variable-slope l?�yrinthic network that precludes the comparatively easy survey method required of th - uniform-slope and unbroken lines of a surf-swept ocean beach depicted by the growinr; areas at Point Steele Beach (Plate 11, p. 98 ), Kanak Island and Katalla Beach (Plate 17, p. 104 ), Softuk Beach (Plate 18, p. 1 05), Polly Creek Beach (Plate 23) and Swikshak Beach (Plate 24 ).

In order to survey these beaches initially, several horizontal control stations, established by the U.S. Coast and Geodetic Survey, were located and marked with 4 by 4 foot (1.22 by 1.22 m) squares of 1/4-inch (6.35 mm) plywood painted \vith flourescent red paint. These markers could be seen with the naked eye from distances of approximately 5 miles (8 km). To further facilitate triangulation, a number of 30-foot (9.14 m) tall spruce saplings were placed at the +3 foot (+0.91 m) tide level of some study sites. The saplings were placed into holes drilled with an ice auger and anchored by wiring each to three sand-filled burlap bags or to three spruce bolts buried approximately 3 feet (0.91 m) deep in the substrate.

A skiff was used to travel from one triangulation point to the next. Essential tools consisted of: (1) a Suunto KB-14 fast accuracy compass with which horizontal angles to 1/6 of 1 degree could be obtained. The needle card of this compass stabilizes for reading in less than 1 second of time. This instrument was used in a hand-held position or rested on a Jacob Staff, depending upon wind conditions. (2) a hand level; and (3) a leveling rod to which was fastened a post whereby the rod could be placed erect at any point on the substrate without the need of a rodman.

Cross-triangulation to known points and tide levels produced a substantial series of points from which to plot the contours of the bars at the -3 foot (-0.91 m) tide level. Slope measurements taken at many locations facilitated the plotting of bar tops and the +4 foot (+1.22 m) tide levels (upper habitable range).

From the plotted chart (on file at the Cordova ADF&G office), areas, distances, habitat

181 Table 58. Method for allocation of sampling effort for razor clams in mark and recapture studies.

(1) (2) (3) ( 4) (5) (6)

100 653 65300 0.066 4 2

80 2340 187200 0.188 11 3

65 3912 254280 0.255 15

4

50 4506 225300 0.226 14

5

35 4165 145775 0.146 9

6

25 3319 82975 0.083 5

7

15 2385 35775 0.036 2

8

Sums 996605 1.000 N = 60

Explanation of columns:

(1) Stratum number where 1 = +4 ft. (+1.22 m) tide level and 8 = -3 ft. (-0.91 m) tide level. (2) Distance between tide levels. (3) Constant obtained from Table 31. ( 4) (2) X (3). (5) ( 4) expressed in proportion, which is the weighting for allocation. (6) Allocated sampling effort, i.e., [(5)j x N], where N = total samples desired and the smallest subsample must be >2 for determination of variance.

182 Pla te 23. Polly Creek Beach, west side of Co ok Inlet, lo oking northeasterly with Redoubt Po in t in the background.

183 Pla te 24. Swikshak Beach, northwest side of Shelikof Strait, Alaska Peninsula, looking northeast.

184 types, and biological communities are easily overlaid and convenient reference is made for population estimates.

Dredging

During July 1971, several drags were made with a dredge between Boswell Bay, Hinchinbrook Island, and Egg Island Channel (Fig. 3, p. 21) to confirm rumors, speculation, and statements regarding subtidal razor clam abundance. Keen (1963) stated that Siliqua is found to 30 fathoms (55 m); dungeness crab (Cancer magister) fishermen occasionally report live razor clams recovered from crab pots that had been stuck in the sand; and extrapolation of the Point Steele Beach gamma distribution (Table 32, p. 118) implied subtidal abundance. The objective was to dredge at 5-fathom (9.14 m) intervals (from mean lower low water) to 30 fathoms (55 m) or to where further sampling revealed no clams. This objective was not fully realized due to prevailing weather conditions.

The dredge I designed ran on skids 6 inches (15.24 em) wide by II feet (3.35 m) long and spaced 4.5 feet (1.3 7 m) apart. The combination digging-ramp section was 6.5 feet (1.98 m) long and 18 inches (45.72 em) wide, and was adjustable so the depth of cut could he controlled from I 0 to 18 inches (25.4 to 45.7 em). The I 0-inch (25.4 em) depth was used for all drags as deeper cuts caused too much resistance (water was not pumped to the cutting head). Substrate and clams rode up the ramp and dropped into a raised 2-foot- (0.61 m) square box lined with expanded steel mesh, which acted as a sand spiller. Remaining items passed into a double mesh bag, the outer bag was heavy 2-inch (5.08 em) mesh and the inner bag 1/2-inch (1.27 em) herring seine. Plates 25 and 26 show detail of the design. The dredge was towed by the Alaska Department of Fish and Game vessel Montague.

Since the dredge weighed approximately I ,400 pounds (635 kg) and the Montague was not specifically rigged to handle it, dredging could only be done when the water was relatively calm as too much rolling of the vessel would have compounded the hazard in the operation. As a result, due to weather conditions and other charter commitments, only four days were allowed for dredging.

A total of ten drags were made, the results of which are shown in Table 59. Each drag lasted about 30 minutes, and distances covered were estimated with a "Rangematic Distance Finder." Due to the variability of the bottom (sand, silt, clay layering), the distance covered by the drags varied considerably, ranging from 300 to 700 yards (274 to 640 m). This dredge was considered to be extremely inefficient, and all clams captured were damaged. Damage ranged from minor structural fractures to complete mangling. In some instances only the siphon was evidenced. This study, though brief, did substantiate the occurrence of razor clams to at least 11 fathoms (20 m) below mean lower low water.

185 Pla te 25. Top view of the razor clam dredge aboard the M/ V Montague.

186 Pla te 26. Razor clam dredge being swung over the side of the M/ V Montague of f Strawberry Poin t, Hin chin brook Is land.

187 Table 59. Results of subtidal dredging for razor clams, Boswell Bay to Egg Island Channel, Cordova Sectors 1 and 2, July, 1971.

Drag Number Number Area Depth (fathoms) razor clams

1 Off Boswell Bay 3 to 5

2 Off Boswell Bay 5 to 7 0

3 Strawberry Channel 11 to 13 3

4 Off Egg Islands 5 5 Off Egg Islands 5

6 Off Egg Islands 6

7 Off Egg Islands 5 to 7 0

8 Egg Island Channel 4 1/4 0

9 Egg Island Channel 3 1/2 to 6 2

10 Egg Island Channel 10

188 APPLICATION OF DISCRIMINATORY AND SEQUENTIAL ANALYSES AS AN ADJUNCT TO THE SHELLFISH SANITATION PROGRAM

Differentiating between two or more populations on the basis of multivariate measurements can be of distinct value in surveillance of approved and nonapproved razor clam growing areas in Alaska and perhaps elsewhere. With development of Alaska's shellfish sanitation program , fresh or quick-frozen razor clams (whole, unshucked) will, in time, undoubtedly be packaged and sold in plastic or paper trays sealed with transparent film . These clams will most likely be marketed through large chain stores intrastate and through similar outlets in National Shellfish Sanitation Program member states or nations. An adequate interception period will be designed to allow fo r: 1) checking origin should subsequent contamination by P.S.P. or pollutants occur; or 2) checking merely to determine the growing area fr om which the samples may have come to substantiate the effe ctiveness of the shellfish sanitation program with regard to controlled harvest areas.

I feel that the capacity to discriminate between groups of razor clams and classify them according to growing area (to the extent that the odds against the occurrence of error in classifying a respectable sample of suspect clams is in the magnitude of 1000 to 1 or greater) will serve a judicial fu nction in thwarting illicit operations. It must be emphasized, however, that cases in court utilizing the hereinafter described methods for razor clams are, as yet, untested.

I have found in numerous instances that significant differences in valve length are observed at the nth annulus among razor clams from different growing areas after attaining a certain age, whether of specific cohorts or from a composite sample from which specific annuli are measured fr om clams of varying age. Others have shown variation in growth of bivalve molluscs by area (Weymouth, McMillin, and Holmes, 1925; Tegelberg, 1964; and Bourne and Smith, 1972) but a search of the literature for employment of growth variation as a surveillance tool could not be found. Ideally, only clams of the same year-class (pure samples) should be used for best results in court due to the variability that may occur fr om year to year in growth increment as applies to any specific annuli chosen as characters. However, use of composite year-classes (composite samples) to obtain characters appears to be acceptable provided that sample sizes are large enough and proper weighting procedures are observed. Practically speaking, then, because of the difficulty that may arise in procuring a large enough pure sample and subsequently seizing enough specimens that conform to the year-class of the discriminants, composite year-classes are recommended from which to obtain characters for discrimination and classification.

Discernment of Annuli

One of the first problems to be encountered is correctly distinguishing specific annuli. Ages of razor clams fr om certain growing areas are often difficult to determine due to the heavy, darkened periostracum. The following method is offered to fa cilitate discernment of annuli, not only in razor clams, but other clam species as well :

(1) Remove the periostracum by brushing with a 40 percent solution of nitric acid.

(2) Rinse in cold, fr esh water.

(3) Immerse valve in a 50 ppm aqueous solution of Alizarin Red and allow to remain for 24 to 48 hours.

189 (4) Remove from Alizarin Red solution and immerse in a 1 percent solution of nitric acid for approximately 45 minutes.

(5) Remove from acid solution, rinse with cold, fresh water, brush off remaining film, and dry for age determination.

Annuli of razor clams and surf clams (Spisula) will show as definite light rings on the purplish background. For clam species without a periostracum (Pro tothaca, Saxidomus, Mya, etc.) only steps 3 to 5 need be observed after brushing away adhering substrate. On these species, allow the acid to etch away all surficial stain; this leaves a dark, hairline residue along the annulus.

I computed discriminant functions from a variety of annuli (utilizing three characters at a time) and found that the annuli which afforded maximum discrimination, in groups of three, were the third to the seventh. Next, it was useful to know how well five characters would work in discrimination problems. To this end, the lengths of the third, fourth, fifth, sixth, and seventh annuli of 1020 razor clams representing 30 growing areas (one from Masset, Graham Island, B. C.; the remainder from Alaska) were entered into a computer. Results indicated that the seventh annulus contains about 78 percent of the information; the third contains about 18 percent; the fifth contains about 7 percent; the fourth contains about 3 percent; and the sixth contains little or no information. Therefore, the third and the seventh annuli contribute approximately 90 percent of the information from the annuli data and for simplicity and practicality, it is suggested that attempts to discriminate and classify be limited to these two measurements.

The Problem of App roved and Unapp roved Growing Areas

There are a minimum of 4 7 known, geographically separated razor clam growing areas in Alaska; ranging to 1350 miles (21 73 km) apart (Fig. 8, p. 30). To date (1975), only three of these growing areas are approved for commercial harvest, yet all areas must be kept under scrutiny. Thus, a surveillance program is needed to discourage the harvesting of clams from unapproved areas and prevent unapproved shell stock from entering intra and interstate commerce. Patrolling this vast coastline on a routine basis is obviously an expensive task. Nevertheless, it must be done and this method of classifying clam stocks offers to enhance the overall effectiveness of the surveillance system.

Analysis of An Anticipated Typical Case

A harvester delivers to a packing plant N razor clams which he claims to have obtained from approved growing area #3. It is suspected, however, that the clams did not come from area #3, but from an unknown, unapproved growing area. Upon questioning, the suspect signs a statement that the supposed harvest location was in subarea C of area #3 . The regulatory official takes a sample of size n of the suspect's clams and attempts to discriminate between the means L3 and L7 of the suspected illegal clams and the tabulated values of clams from the indicated location of area #3. Depending upon the outcome of the calculations, the clams are allowed to be sold, or they are confiscated. There are two possible types of error.

Type I error (Producer's Risk): The clams were obtained at area #3, subarea C, but the regulatory official decides they were not� this case, the harvester suffers. The probability of this type of error is called a. It is obvious that this error should be small.

190 Again, smaller a will require larger sample size n. Type II error (Consumer's Risk): The clams were not obtained at area #3, subarea C, but the regulatory official decides they were. In this case, the public suffers (possibility of P.S.P.) and the shellfish sanitation program also suffers. The probability of this error, which is called i3 , should obviously be quite small. But to lower this probability the required sample size must be increased substantially.

The sample size, then, depends upon four quantities:

I. unacceptable quality 2. acceptable quality 3. producer's risk 4. consumer's risk and the following notation is used, as described by Moroney (1951):

PI = the acceptable quality, expressed as fraction defective.

a tho probability of rejecting a lot of thia uccoptablo quality.

p2 = the unacceptable quality, expressed as fraction defective.

i3 = the probability of accepting a lot of this unacceptable quality. It should be kept in mind that acceptable and unacceptable qualities are identified by criteria characterizing the fraction defective, that is to say, the percent error of misclassification for an individual associated with any group [as discussed by Rao (1952)] .

A decision to accept or reject a lot of clams may be relatively easy to make based on a small sample of, say, 15 clams with a= 0.01 and 13=0.0 1 if clams from two beaches, A and B, were:

A = (L3, L7) = (30, 130) and

B = (L3, L7) = (70, II0), but for the same a and 13, if L A=(L 3, 7) = (40, 110) and

B = (L3, L7) = (45, 115) the required sample size may have to be several hundred, in which case the effort expended to realize a significant difference would probably preclude its worth.

Determining levels of significance with the F distribution for discriminatory analysis is described by Moroney (1951) and by Rao (1952). Where threshold significance is evidenced, or where percent error of misclassification is unacceptable after comparing samples of size n = 30, use of a sequential inspections chart in conjunction with an average sample number curve is of particular value for decision making.

If we allow that PI = O.OI, a= 0.05, P2 = 0.05, and i3 = 0.05, then calculation of

191 the characteristic constants, h 1 , h2, and s follows by the method outlined by Moroney (1951), where, since a = 13 , then h1 = h2 = 1.7836; and s = 0.025. Acceptance and rejection lines are determined from these constants and appear in Fig. 30. Again, the characteristic constants are employed to construct an average sample number curve, which appears in Fig. 31.

When a decision cannot be made using samples of size n = 30, it is seen from Figs. 30 and 31 that the sample size must be increased to n = 70 before acceptance would be possible under the prescribed conditions of the operating characteristic (Table 60).

Examples of High Risk and Low Risk Areas

The razor clam growing areas of Cordova are considered to be low risk since commercial quantities of clams are all located in an approved area. Also, this entire area coincides with major salmon and crab fishing grounds and is under continuous surveillance. In addition, areas (on Fig. 8) #1, #2, #'s 4-6 and #'s 8-12 contain subsistence levels only and #3 would require offshore dredging that would be readily observed.

The razor clam growing area at Polly Creek is considered to be of moderately high risk due to the extensive razor clam-bearing beaches in the vicinity of Cook Inlet; that is, #13 (Nuka Island) to #19 (Augustine Island), specimens from which have not been routinely tested for the �re::::ence of P.S.P.

The razor clam growing area at Swikshak is considered to be of high risk due to error in misclassifying specimens from Halibut Bay (#48) on Kodiak Island which, together with razor clams from Alitak (#46), have evidenced high levels of P.S.P., i.e., 217 ug and 132 ug, respectively, during 1971 and 1972. Beaches are considered unsafe for harvest when the P.S.P. level reaches 80 ug/1 OOg.

Swikshak beach can be dissected into 1-mile (1.6 km) partitions in such a manner, however, that clams obtained from the middle of each of the four partitions on this 4-mile (6.44 kn1) stretch of beach can be classified to a certain degree, as shown in Table 61. The error of misclassification for razor clams between Swikshak A (the southernmost partition) and Swikshak B is as high as 28.77 percent. When the values of Swikshak C and Dare pooled, the errors of misclassification between Swikshak CD and Swikshak A, and Swikshak CD and Swikshak B are 0.01 percent and 31.56 percent, respectively. From Fig. 30 we see that the decision to reject clams from Swikshak A as coming from Swikshak CD is easy to make, whereas indecision will prevail until more samples are inspected for the Swikshak CD - Swikshak B problem.

Since increased sampling may not reduce the error appreciably, and it is of critical importance to make a decision, Rao (1952) provides a method in which the probabilities of wrong decisions are at assigned levels. In the example of the Swikshak B sample with 1r2 = 0.375 and the Swikshak CD sample with 7Tl = 0.625, it has been determined that the point of section (i.e., the critical value separating the individuals of the two groups) is 18.812 and if the discriminant value exceeds 18.812 the individual is assigned to Swikshak CD. The point corresponding to the 4.9 x 1 o-8 percent level of errors for the Swikshak B samples is :

18.729 + 6.51 D = 19.8370 D = 0.1702 and unless the discriminant value exceeds 19.83 7, specimens from sample sizes>30 cannot

192 lfl E ro - u

(]) - _o ro +- o_ (]) u u ro c :::J

'+-- 0

L (]) _o E \0 :::J w c

(]) > ·- +- ro - :::J t \ 119 E tes :::J E:O J o" \ 11\.) 2 � c t u

0�--��--�---.----.----P----�--�--�----�---.----P---�--��--�--�--� 10 20 30 40 50 60 70 80 90 10) I I 0 120 130 140 150 160

Cumu lati ve samp le size = n

Fig. 30. Sequential inspections chart fo r testing suspect lo ts of ra zor clam shellstock. 140

130

Q) _c +-

+- 120 CD

c 0

(f) II0

u Q) GJ u -

CD Eo. IOO CD OJ (f) c ·- GJ _c _c U+- 90 CD GJ c L · -

GJ U L GJ 80 0 · - '+- '+- Q) · - _o (f) (f) 70 u CD QJ- +- u u (f) Q) · - o__ E (f) 60 c+- c GJ (f) u E L CD GJ 50 - o_ u u '+- GJ 0+- CD 40 L-1- GJ (f) _o E ::J c 30

GJ Ol CD L 20 GJ Curve fitted by eye >

10

2 3 4 5 6 7 8 9 10

Percent misclassified in samp les ins pected

Fig. 31. Average sanztJle number curve fo r testing suspect lo ts of razor clam slzellstock.

194 Table 60. Operating characteristic for accepting lots of razor clam shellstock of different quality.

Lot fraction 0 = 0.01 s = 0.0250 = misclassified P I P2 0.05 1

Probability of h2 acceptance 1 (1-a) = 0. 95 hl � h2 = 0.50 B = 0.05 0 \0 VI i.e. Percentage of lots accepted is 100 95 50 5 0

When percent misclassified in 0 1 2.50 5 100 the lot is be asserted to belong to Swikshak CD, although provisionally they will be put into the Swikshak CD category as soon as the value exceeds 18.812. Similarly, the 4.9 x w-8 percent value for the Swikshak CD samples is :

19.920 - 6.51 D = 18.8120 and unless the value of the discriminant function is below 18.8120 the specimens cannot be asserted to belong to the Swikshak B group.

In a similar manner, assignment of individuals to Swikshak A or Swikshak B can safely be made at the 4.5 x w-8 percent level of errors, with rr2 = 0.565 and rr1 = 0.435, respectively, and where the point of section is 11.0319, indicating that individuals from sample sizes>30 can be asserted to belong to Swikshak A when the discriminant function value falls below 10.5071. And individuals can be asserted to belong to Swikshak B when the discriminant function value exceeds 11.03 19. That is :

10.5486 + 6.55 D = 11.0320 D = 0.0738 and 10.9904 - 6.55 D = 10.5070

Thcu:ofon�, lf d susved atlemvleu lu sell Haliuu l Bay clams under the pretense of coming from Swikshak C or D, a decision to reject this assertion could be made with ease. If, however, the suspect claimed that the Halibut Bay clams came from Swikshak A or B, as indicated in Table 61, there is insufficient evidence from the small sample of Halibut Bay clams inspected for this analysis to establish a difference and the regulatory official would have to rely on large samples, i.e., at least n = 70 or statements from individuals at known locations at the time in question, or both.

In summary, then, growth data of razor clams can be used in decisions to accept or reject suspect lots and sequential analysis provides additional input towards decision making. In general, however, all growing areas, approved and nonapproved, must be regarded as potential high risk areas and, therefore, must come under routine surveillance. Additionally, determination of lengths of annuli for discriminating between any two groups should be done by one person to insure consistency of measurements and interpretation of the annular rings.

196 Table 61. Results of discriminatory analysis applied to various razor dam growing areas in Alaska.

Percent Probable occurrence of wrong Test Sample Size F Value classification

Big Point Bar 1J 22 VS 35.24 > F.99 <2.6 X 10 -lO Polly Creek Beach Jj 30 Big Point Bar 22 VS 40.02 > F.99 <5.7 X 10 -5 Swikshak Beach, subarea A ]j 78 Polly Creek Beach 30 VS 12.14 > F.99 0.17 Swikshak Beach, subarea A 78

\Q Polly Creek Beach 30 -....] VS 17.54 > F.99 <2.0 X 10 -7 Augustine Island jj 30 Polly Creek Beach 30 VS 9.0�. > F.99 3.84 Nuka Island JJ 21 Swikshak Beach, subarea A 78 insufficient VS 0.59 < F.95 evidence to Halibut Bay 11 establish a !iJ difference

Swikshak Beach, subarea B 60 insufficient VS 1.35 < F.95 evidence to Halibut Bay l 1 establish a difference Table 61. (continued)

Percent Probable occurrence of wrong Test Sample Size F Value classification

Swikshak Beach, subarea C 45 VS 6.0E > F.99 0.01 Halibut Bay 11

Swikshak Beach, subarea D 55 VS 6.1: > F.99 <5.7 X 10 -5 Halibut Bay 11

Swikshak Beach, subarea C 45 insufficient VS 0. 1 ::: < F.95 evidence to Swikshak Beach, subarea D 55 establish a difference

Swikshak Beach, subarea CD 100 \0 -lO 00 VS 7.3L > F.99 <2.6 X 10 Halibut Bay 11

Swikshak Beach, subarea CD 100 vs 22. 1E > F.99 31.56 Swikshak Beach, subarea B 60

Swikshak Beach, subarea CD 100 VS 45.84 > F.99 0.01 Swikshak Beach, subarea A 78

Swikshak Beach, subarea A 78 vs 7.44 > F.99 28.77 Swikshak Beach, subarea B 60 1/ Cordova 2; West side of Cook Inlet 3; Alaska Peninsula 4; Lower Cook Inlet 5; Northwest Gulf of Alaska 6/ Kodiak Island SUMMARY

History of Commercial Harvests m Alaska

Alaska's commercial razor clam fishery originated in 1916 at Cordova. Subsequently, Swikshak Beach on the Alaska Peninsula and Polly Creek Beach on the west side of Cook Inlet were exploited. These three growing areas were the mainstay of Alaska's clam industry for many years. Problems with paralytic shellfish poison in canned Alaska hardshell clams became noticeably apparent during the 1940's and the impact of these problems on the razor clam industry were felt in the form of beach closures. Continued problems with hardshells resulted in a complete suspension of this enterprise in Alaska in 1954. During the 1950's severe competition from Atlantic Coast and Oriental clam packers hurt Alaskan and other Pacific Coast clam packers. Razor clam production in the Cordova area dropped sharply by 1960, but increased production from the Kodiak Island area maintained Alaska's overall production. Mechanized harvest equipment introduced in Alaska during 1963 was designed to offset increasing competition from foreign and domestic packers, but this measure failed to achieve its intended goal.

History of Toxicity Problems in Alaska The year that the Territory of Alaska became a member of the National Shellfish Sanitation Program (formed in 1925) is not known, but subsequent problems with butter clams resulted in Alaska's dismissal as a member of the N.S.S.P. in 1954. In 1963 the Alaska Department of Health and Welfare declared all beaches in Alaska suspect of containing poisonous shellfish, and during the following 7 years all clam growing areas in the state remained technically closed and unapproved for commercial utilization.

Funds became available to the Alaska Department of Fish and Game in 1969 to initiate investigations aimed at the eventual reopening of the three historic razor clam growing areas for commercial harvest, namely, Cordova, Swikshak, and Polly Creek. Background data on paralytic shellfish poison and sanitary conditions of the growing areas were gathered and assessed, and by April 1970, the three growing areas were approved for commercial harvest. However, fresh and frozen razor clams were limited to intrastate shipments only. Efforts were then extended to regain membership in the National Shellfish Sanitation Program. Requirements for readmission to the N.S. S.P. were as follows: (1) establishment of an effective surveillance system, (2) establishment of an effective monitoring program, (3) procurement of all data concerning paralytic shellfish poisoning in razor clams, ( 4) development of laboratory capabilities for rapid bioassays, (5) evaluation of growing areas for pollution potential, and (6) development of a memorandum of understanding among the State of Alaska's shellfish regulatory agencies. These agencies are the Alaska Department of Fish and Game, the Alaska Department of Public Safety, and the Alaska Department of Health and Social Services; the latter assuming overall responsibility for the program. During 1973, Food and Dmg Administration officials conducted sanitary surveys of the three previously mentioned historic razor clam growing areas. Alaska regained membership in the N.S.S.P. on February 24, 1975.

Razor Clam Biology

Razor clams are found in Alaska from the Southeastern Panhandle to the Bering Sea and Aleutian Islands. There are 49 known razor clam growing areas in Alaska.

]99 Sex ratios are 50:50 and the sexes display similar rates of growth. Attainment of sexual maturity depends more on size than age and about 65 percent of the clams achieve sexual maturity in their third full year of life. Spawning occurs when 1,350 or more temperature units (cumulative Fahrenheit degrees of the maximum daily deviation ± 32° F. that are observed from January 1 to the onset of spawning) have accumulated. The approach to the threshold of spawning is governed by time and temperature. During this phase of ripening, pH of the gonad changes from alkaline to acid. After spawning has begun, its progress appears to be primarily a function of temperature and the pH of the gonad gradually shifts back from acid to alkaline. Completion of spawning is a function of time, whereupon gonad pH reaches a level of alkalinity comparable to the initial stages of ripening.

Growth rates vary considerably among areas and very large clams are generally not the oldest. Some specimens collected in the Cordova area had attained the age of 18 years. Legal size of razor clams from the Cordova, Swikshak, and Polly Creek growing areas should be 4.5 inches (114 mm) in valve length.

Age-length-weight relationships are of value to management personnel in estimating biomass and year-class strength.

Frequency of occurrence of razor clams by tide level on the low tide terrace in the Cordova area is in the form of a negative binomial distribution having a mode at mean lower low water. Upper habitable range is at the +4.5 foot (+1.37 m) tide level and specimens have been recovered to 180 feet (54.86 m) below mean lower low water.

Substrates containing 2.2 percent or more of clay fractions may cause mortalities in early life stages of razor clams.

Age and total valve length are greater in razor clams at lower tide levels.

Fecundity estimates of razor clams 40 mm to 180 mm in total valve length range from 0.3 to 118.5 million ova per clam.

The natural mortality rate of Alaska razor clams is fairly low, resulting in survival to at least 18 years. Survival rate from 3 years of age to the asymptote is estimated at 0.4029 per year in the Cordova area.

Young razor clams 10 mm in valve length are capable of voluntary lateral movement along the exposed beach surface to about 2 feet (60 em). Large razor clams are believed incapable of voluntary lateral movement and any obvious relocations of these specimens are thought to result from substrate instability.

Drift drogues may simulate larval razor clam drift patterns. Recovered drogues were found at or near razor clam beds up to 650 miles distant from the release area. Certain localized conditions involving unique bar formatiotls, low salinities, slow current velocities, and concentrated eddying effects may allow the formation of pocket razor clam populations bearing gene pools which give rise to significant numbers of individuals having a similar unusual character (i.e., shell indentation or periostracal pigmentation) peculiar to that area.

Certain variables account for whether razor clams "show" or don't "show" . These variables are water vapor deficits, air temperatures and atmospheric pressures at sea level for the same day and the day before clams are observed; low tide height, water surface, and wind speed on the same day that clams are observed. These variables play an important role in population estimation.

200 Survey Techniqu es

The following five methods are available for estimating the size of razor clam populations: 1) employment of density indicators and probability distributions on the low tide terrace (this is of value in estimating the abundance of clams 90 mm and larger); 2) stratified random sampling (this is used for obtaining estimates of clams 35 mm and smaller when substrate is screened); 3) probabilities and reapportionment [this may replace (2) with adequate sampling]; 4) combining estimates based on dug and screened clams (this is of value in calculating abundance of clams less than 90 mm); and 5) mark and recapture (this is not recommended except on the most stable habitats).

Beach surveys can be adequately conducted by taking compass points to flagged horizontal control stations and triangulating to poles emplaced along the exploitable habitat on the low tide terrace.

Discriminatory and Sequential Analysis

Calculation of discriminants and utilization of a sequential sampling scheme based on probabilities of acceptance and rejection of lots is very useful in differentiating between two or more populations on the basis of the average length of the third and seventh annuli. With the development of Alaska's shellfish sanitation program, this method lends itself as an adjunct to the surveillance system.

201 APPENDIX 1. Age and length of razor clams dug commercially during 1969 and 1970 in the Cordova, Alaska, growing areas.

202 Appendix 1 a. Quartiles, means, and standard deviations of the age and length of razor clams dug commercially by P. Conrad, May 1969, at Rockslide Bar. 100

- -- N = 137 75 - -- --

X= 7.01 + 1. 19

25

5 6 7 8 9 10 11 12 1 3 14 15 16 17 18 AGE (years)

75 ------N = 1 3 7

X= 131.00 + 7.9992

so ------

25 ------

110 120 130 140 150 160 170 Length (mm)

203 Appendix 1 b. Quartiles, means and standard deviations of the age and length of razor clams dug commercially by P. Conrad, July 10, 19fi9,::�t the bar between Big and Little !v!:ummy Island. 10

7 ------

N = 205

X= 8.43 + 2.59 5 ------

,-.... t) ;>, (.) !=:

-�...... c;

8 7 ------· ------N = 205

X= 140 .48 + 10 .36

5 ------

2 ------

110 120 130 140 150 160 170 Length (mm) 204 Appendix 1 c. Quartiles, means, and standard deviations of the age and length of razor clams dug commercially by P. Conrad, April 19 and 20, 1969, at the bar between Big and Little 10 Mummy Island.

7 ------

I N = 389 I X= 8. 12 + 2.33 5 I I I I I I 93 I;

.\::;..... 5 6 7 8 9 10 11 12 13 14 15 16 17 18 ro AGE (years) ] 10 ...... ro '3 s 8 ) 7

N = 389

X= 135 .41 + 11. 42 ) 5

) 2

) 110 120 130 140 150 160 170 Length (mm)

205 ) Appendix 1 d. Quartiles, means, and standard deviations of the age and length of razor clams dug FP"s:r h 1 Q(';Q commerci<�llv., hv., .L - Fooi---l e Out.;:ii------le- uu l.;:l---<�ni�---l·, --Anr--ril- �, -- ..., _ ·

100

75 ------

N = 74

50 ------x = 1 o. 14 + 1.46

AGE (years )

N = 74 75 ------X = 128.73 + 8.24

50 ------

25 ------

110 120 130 140 Length (mm)

206 Appendix 1 e. Quartiles, means, and standard deviations of the age and length of razor clams dug commercially by C. Olsen, February 9, 1970, at Big Point Bar. 100 (Co rdova Sector #1)

7S ------N = 33

X = 6. 79 + 0.64

so ------

2 S - ----

(!) 9 11 12 14 16 17 .-:::; 5 6 7 8 10 13 15 18 ro 100 AGE (years) (i)1-<

7S

N = 33

X= 128.45 + 7.62

so

2S ------

llO 120 130 140 150 160 170 Length (mm) 207 Appendix 1 f. Quartiles, means, and standard deviations of the age and length of razor clams dug commercially by Wes Ladd at the bar bet\:t.'een Big and Little 1\1ummy Island, �,1ay 1970. 100

75 ------

N = 3 0

X = 8. 43 + 1. 50

5

25 ------

Q) > , ') ·- 5 6 7 8 9 11 12 .l..) 14 15 16 17 18 ...... 10 ro AGE (years ) v1..... o Q)

·-> ...... ro "3 s 8 7

N = 30

5 X= 138. 82 + 9.62

25 ------

llO 120 130 140 1.50 160 170 Length (mm)

208 Appendix 1 g. Quartiles, means, and standard deviations of the age and length of razor clams dug � ...-...... _.... o..,..,...;nll·n h·u ll./ T o.rlri 1\.T ��+h a$'1C�t ll:�CT 1\tfnrnrnu TC'l�J�nr1 �IJI-r 1\.tfg·u ")� 10.._-"70' .._. • ff . .L 'U..I.l t..ll.VU,::H .. ..._..U..L .J..U.U.J -..-...; ' \.IVJ11.111VJ.\..IJ.Q..l.I.J U J .L....<.t.UU' ..ltJ.l.f:, .l.l.L\A..l.l.l.l.l..LJ ..&.I,::U.U.J.J.'-" '

10

7

5

5 6 7 8 9 10 11 12 13 14 15 16 17 18 AGE (years )

7 ------

N = 30

X= 129 .88 + 4.50

5

2 ------

110 120 130 140 150 160 170 Length (mm)

209 Appendix 1 h. Quartiles, means, and standard deviations of the age and length of razor clams dug commercially by P. Conrad, Canoe Pass Trail Bar, June 2, 1970.

100

------7S

N = SO

+ X = 7. 82 0. 48

so

2S

s 6 7 8 9 10 11 12 13 14 15 16 17 18 AGE (years)

------7S

N = 50

X = 140. 36 + 7. 22

------so - -

------2S ------

llO 120 130 140 1SO 160 170 Length (mm) 210 Appendix 1 i. Quartiles, means, and standard deviations of the age and length of razor clams dug commercially by W. Ladd, Shirttail Bar #3, June 3, 1970.

100

7

N = 50

x = 8 • 88 + 1.2 6 5

,-.., 2 t,'2. "-'

;>. (.) � Q)

Q)& <1:1 Q) :> ...... 12 13 14 15 i6 i7 18 +-> 5 6 7 8 9 10 11 eli - Q) AGE (years) 1-< 10 Q)

.�+-> eli - ;::::s s

8 = 50 7 N

x = 130.46 + 8. 33

5

2

110 120 130 140 150 160 170 Length (mm) 211 Appendix lj. Quartiles, means, and standard deviations of the age and length of razor clams dug l't"'ln1n1Prro1<>1h, hu WPc <>nrl Mnllu T <>rlrl Tn nP Q 1 070 <>t Turin "Rnf'lrc _ ..._.. �.._...... -._..._ _...._._...... ,..J ._..J '' '-'V. _.._..__ .._,..._... '-' ""J ...... ---, "" '-'"".0...0."" .._., .l./I 'V'' o.A<'- A. •f.&..I.-.L ..._ ".....,...... l.'Oo.Uw 100

75 ------

N = 49

X= 9.16 + 1. 73 5

2 ,.-,

�'-' ;;.., (.) � <]) ;::l 0" <]) <1::: <]) 5 6 7 8 9 10 11 12 14 15 16 17 18 . ....:::. ro - AGE (years) <]) 10 1-< <]) . ....:::. ro - ;::l s 8 7

N = 49

X= 137.12 + 8. 82

5 ------

25 ------

Length (mm)

212 Appendix 1 k. Quartiles, means, and standard deviations of the age and length of razor clams dug commerciall�{ by L. 1vlax'vvell at Canoe Pass Trail Bar, 1970. 100

N = 267

X= 6.95 + 1.29

50 ---

5 2 - -

5 6 7 8 9 10 11 12 13 14 15 16 17 18 Age (Years)

75 ------N = 267

X= 130.78 + 9.24

) ------50 -

) 25 ------

)

110 120 130 140 150 150 170 Length (mm)

213 ) APPENDIX 2. Identification and description of razor clam study plot sites in Cordova Sector 1.

Site Number One

Location: Between Big and Little Mummy Island and on the west side of a dead-end channel that partially separated the bar from Big Mummy Island and Filipino Island flats at low tide.

Remarks: This site was abandoned due to its difficult accessibility at low water and poor drainage characteristics.

Site Number Two

Location: Approximately 200 yards northeast of Little Mummy Island on the west side of the main channel that separates Little Mummy Island from the bar between Big and Little Mummy islands.

Plo ls : Eighl plols were eslal>lisheu al 1 fo ul wHluUI iule1 vals fw m lhe -3 to the +4 foot tide levels. Each plot measured 10 by 100 feet with the respective tide level located along the center line of the plot (Appendix 2a). Total plot area = 8000 ft.2.

Slope: 1.75% (i.e., 1.75 feet rise per 99.98 feet of horizontal run).

Substrate: 99.952% fine sand.

Other mollusc members of the community:

Clinocardium nuttalli (1/4" to 2" approximately)

Spisula polynyma (1/2" to 4" approximately)

Macoma inconspicua (1/2" approximately)

Snail (not identified)

Site Number Three

Location: Approximately 2 miles west of Twin Rocks at the tip of a spit facing west on the main inside channel to Little Mummy Island. This area was called "Erikson Bar" by the author but it is not the same Erikson Bar as evidenced in 1939 and 1954 which apparently eroded to become "Surf Bar" in 1959 which, in turn, was obliterated by the 1964 earthquake.

Plots: Eight plots were established at 1 foot contour intervals from the -3 to the +4 foot tide levels. Each plot measured 10 by 100 feet with the respective tide level located along the center line of the plot (Appendix 2b). Total plot area = 8000 ft.2 . Slope: 2.62% (i.e., 2.62 feet rise per 100 feet of horizontal run).

214 APPENDIX 2. (continued)

Substrate: Not determined.

Other mollusc members of the community:

Macoma inconspicua (1/4" to 1/2" approximately)

Clinocardium nuttalli (1/2" to 2 1/2" approximately)

Macoma irus (3/4" approximately)

Site Number Four

Location: On the east side of the bar across the main channel from Canoe Pass trail. The site was on the west side of the dead-end gutter.

Plots: Seven plots were established at I foot contour intervals from the -3 to the + 3 foot tide levels. Each plot measured I 0 by I 00 feet with the tespedlve title level lut;atetl aluug the ceuter Hue of the plot (Appendix 2c). Total plot area = 7000 ft.2.

Slope: 6.97% (i.e., 4.31 feet of rise per 61.85 feet of horizontal run).

Substrate: 1 00% fine sand.

Other mollusc members of the community:

Macoma inconspicua

Spisula polynyma (to 5 " approximately)

Clinocardium nuttalli (1/2" approximately)

Macoma irus

Site Number Five

Location: Opposite Shirttail Point (Hinchinbrook Island) and in line between the White Alice Station and Little Mummy Island. This bar was called Shirttail Bar #1 by the author.

Plots: Nine plots were established at 1 foot contour intervals from the -3 to the +5 foot tide levels. Each plot measured 10 by 100 feet with the respective tide level located along the center line of the plot (Appendix 2d). Total plot area = 9000 ft.2.

Slope: 3.49% (i.e., 3.49 feet of rise per 99.94 feet of horizontal run).

Substrate: 100% fine sand.

Other mollusc members of the community:

Macoma inconspicua (1/2" approximately)

215 APPENDIX 2. (continued)

Clinocardium nuttalli (l/2" to I 1/2" approximately) (Many)

Mya arenaria (1 1/2 " to 2 " approximately)

Spisula polynyma (l/2" approximately)

Site Number Six

Location: Southwest Ocean Bar on the outside of the spit at the mouth of the new Pot Hole area.

Plots: Seven plots were established at I foot contour intervals from the -2 to the +4 foot tide levels. Each plot measured I 0 by I 00 feet with the respective tide level located along the center line of the plot (Appendix 2e). Total plot area = 7000 ft. 2.

Slope: 8.72% (i.e., 4.36 feet of rlsc per 50 feet of ltUllLuutdl 1uu). Substrate: I 00% fine sand.

Other mollusc members of the community:

Clinocardium nuttalli (1/4" to 1 1/4" approximately)

Site Number Seven

Location: Inside Ocean Bar. This site was in line with South Twin Rock and the Rockslide (located by the U.S.C.&G.S. horizontal control position "Joe" on the Southeast shore of Hawkins Island).

Plots: Six plots were established at 1 foot contour intervals from the -3 to the + 2 foot tide levels. Each plot measured 10 by 100 feet with the respective tide level located along the center line of the plot (Appendix 2t). Total plot area = 7000 ft.2.

Slope: 2.62% (i.e., 2.62 feet of rise per 100 feet of horizontal run).

Substrate: 99.73% fine sand.

Other mollusc members of the community:

Clinocardium nuttalli (1/2" to 2" approximately)

Macoma inconspicua

Mya arenaria (to 2" approximately)

Site Number Eight

Location: At the extreme southwest tip of Twin Rocks Bar.

2 16 APPENDIX 2. (continued)

Remarks: This site was established on May 6, 1969, and was destroyed by tidal currents by July 15, 1969. Further attempts at collecting data from this site were abandoned.

Site Number Nine

Location: Northeast of and across the main channel from the U.S.C.&G.S. horizontal control position "Joe" (which is located on the southeast shore of Hawkins Island).

Plots: Seven plots were established at 1 fo ot contour intervals from the -3 to the + 3 foot tide levels. Each plot measured 10 by 100 feet with the respective tide level located along the center line of the plot (Appendix 2g). Total plot area = 7000 ft.2.

Slope: 5.24% (i.e., 3.40 feet of rise per 64.9 feet of horizontal ru n).

Substrate: 1 00% fine sand.

Other mollusc members of the community:

Schizothaerus capax (6" approximately)

Macoma irus

Clinocardium nuttalli (to 3" approximately)

Spisula polynyma (to 5" approximately)

Mya arenaria (to 1" approximately)

Site Number Ten

Location: On the northeast tip of Concrete Bar (known as Quarry Bar in 1959) and in line with the rock quarry on Hawkins Island and Bluff Point on the mainland.

Plots: Seven plots were established at 1 foot contour intervals from the -3 to the + 3 foot tide levels. Each plot measured 10 by 100 feet with the respective tide level located along the center line of the plot (Appendix 2h). Total plot area = 7000 ft.2.

Slope: 1.75% (i.e., 1.75 feet of rise per 99.98 feet of horizontal run).

Substrate: 1 00% fine sand.

Other mollusc members of the community:

Sp isula polynyma (l/2 to 4") many

217 APPENDIX 2. (continued)

Clinocardium nuttalli (1/2 to 3")

Unidentified gastropod

Site Number Eleven

Location: Approximately 2 miles north-northeast of Point Steele on the east coast of Hinchinbrook Island.

Plots: Twenty-four plots were established by locating 3 series of plots designated A, B, and C 100 yards apart at 1 foot contour intervals from the +5 to the -2 foot tide levels. Each plot measured 5 by 50 feet with the respective tide level located along the center line of the plot. Total plot area was 6000 square feet. Plots A and B were hand-dug while each Plot C (Appendix 2i) was screened. Only Plot C data are used in the analysis as the heavy set of young clams precluded a hauJ-Jug eslilllate iu Plu t� A and B. Data from Plots A + B were used as controls for Plot C.

Slope: 0.38% (i.e., 0.38 feet of rise per 100 feet of horizontal run).

Substrate: 1 00% fine sand.

Other mollusc members of the community:

Macoma inconspicua ( 1 individual)

218 Appendix 2a. Therelative profile of site #2, Little Mummy Island Bar, and corresponding arrangement of study plots.

+6

+5 Study Plots

10 x 100 feet ( each) +4 ,------�

+3 [ �

H HU------··- --- rl t0 Q) +2 -1 - > \0 Q) I t-1 Q) '"0 +1 •ri H r I

z I -----�

-1

-2

-3 [ :=J

100 200 300 Slope Distan ce (feet) Appendix 2b. The relative profile of site #3, Erickson Bar, and corresponding arrangement of study plots.

+6

+5 Study Plots 10 x 100 feet (each) +4 [ I - - --- +3 I I

N N rl +2 0

- 1

- - - - 2 - . - I � - 3 ------I ------:=1

I 100 200 300 Slope Dis tance (feet) Appendix 2c. The relative profile of site #4, Canoe Pass Trail Bar, and corresponding arrangement of study plots.

+6

+5

+4 Study Plots

10 x 100 feet (each) ------, +3 tv --- ···· tv rl +2 l Q) :> I Q) ....:1 Q) +1 '"d ·.-4 H z

-1

-2

-3 ------

100 200 300

Slope Dis tance (feet) Appendix 2d. The relative profile of site #5, Shirttail Bar, and corresponding arrangement of study plots.

+6 Study Plots �0 x 100 feet (each ) +5 I J +4

+3

N N +2 c---·- N J +1 r - J rl (j) z > (j) r-:1 c-- ---·- -J (j) '"0 -1 ·,..j [:-; [---- I -2 I J

-3 ------

100 200 300 400 Slope Distance (feet) Appendix 2e. The relative profile of site #6, Southwest Ocean Bar, and corresponding arrangement of study plots.

+6

+5 Study Plots

10 x 100 feet (each) +4 -l------r· � +3 ------I -l t-0 t-:1 rl +2 w Q) > ------I Q) ------] ,...:1 Q) +1 ------'\j ·rl 1 !:-' -� z ------r- �

-1 ------I -]

-2 ______,- --]

- 3

100 200 Slope Distance (feet) Appendix 2f. The relative profile of site #7, Inside Ocean Bar, and corresponding arrangement of study plots.

+6

+5

+4

+3 Study Plots

�0 x 100 feet (each) N N +2 ..j:::. [� I

,-j +1 QJ :> QJ ....:1 QJ z 'U ·rl E-<

------·--·------, -1

-2 c- I

-3 ------· ------[- .. ------]

��--� ------100 200 300

Slope Dis tance (feet) Appendix 2g. The relative profile of site #9, Rockslide Bar, and corresponding arrangement of study plots.

+6

+5

+4 Study Plots

10 x 100 feet (each) - +3 ------I I .. . t0 +2 t0 VI I l

------, ,...., +1

---·------.., - 1

-2

------..__ --- -3 r ---�

100 200 300 Slope Distance (feet) Appendix 2h. The relative profile of site #1 0, Northeast Concrete Bar, and corresponding arrangement of study plots.

+6

+5 u- +4 Study Plots 10 x 100 feet (each) ] +3 ------c -----] -

-- tv +2 - tv ------I 0\ - ----]

- rl QJ +1 :> ------c - QJ ...:1 QJ z rc:l - -� ·r-1 ------I E-< -�J

------� - 1 - --] I

-2

-3 ------

100 200 300 Slope Distance (feet) Appendix 2i. The relative profile of the Point Steele study area and corresponding arrangement of sample frames.

+6

Sanp le "rames 5 s� uare f e et each

+5 ------0 0 D 0 0 0 0 D +4 �0000 000 +'3 ------� D 0 D 0 0 0 0

IJ f_; +2 ---J ------0 0 0 0 0 0 0 D

� + l > Q) DDODDDDO ,...:) � z ·ri ------t-< 0 0 0 D 0 0 0 0 -1 ------0 0 D D 0 0 0 0

-2 ------000 0 0 0

-3

0 500 1000 1500 2000 Slop e Dis tance (feet) APPENDIX 3. Growth rate of razor clams collected from a variety of growing areas Ill Alaska. Appendix 3a. Growth rate of razor clams at Rockslide Bar. Cordova Sector I.

Number Median Mean Standard 111 Age Ring Length Length Deviation Sample Years Number mm Illl1l lll l11

I 53 0.5 7.39 7.26 I.92

' I 53 1.5 - 23.82 23.84 4.93

I 53 2.5 3 4I.99 42.69 7.62

148 3.5 4 72.00 71.87 11.05

141 4.5 5 99.46 cn.23 12.38

110 5.5 6 I 12.64 112.43 10.79

56 6.5 7 I 21.00 120.50 9.52

18 7.5 8 128.20 126.00 7. 77

2 8.5 9 125.50 I 25.00

2 9. 5 10 I 31.50 131.00

2 I 0.5 I 1 134.50 134.00 Appendix 3b. Growth rate of razor clams at Inside Ocean Bar, Cordova Sector 1.

Number Median Mean Standard m Age Ring Length Length Deviation Sample Years Number mm mm mm

78 0.5 6.77 6.78 2.53

76 1.5 2 24.29 24.90 6.59

75 2.5 3 39.25 43.88 12.56

70 3.5 4 67.00 68.90 12.11

67 4.5 5 91.38 90.88 10.19

44 5.5 6 106.50 106.59 9.70

n () 'i 7 llS .:'iO 117.R3 R.oo 6 7.5 8 1 21.00 124.50 8.78

Appendix 3c. Growth rate of razor clams at Southwest Ocean Bar - Pot Hole Entrance, Cordova Sector I.

Number Median Mean Standard in Age Ring Length Length Deviation Sample Years Number mm mm mm

21 1 0.5 6.16 6. 17 3.00

21 1 1.5 2 26.69 26.54 7.34

204 2.5 3 53.24 48.93 13.34 161 3.5 4 75.70 72.23 12.88

119 4.5 5 90. 17 89.20 10.35

66 5.5 6 104.50 102.77 9. 16

18 (1 .5 7 1 1 1.00 111. 17 7.71

230 Appendix 3d. Growth rate of razor clams at Channel Junction Spit (opposite Twin Rocks), Cordova Sector 1.

Number Median Mean Standard 111 Age Ring Length Length Deviation Sample Years Number mm mm mm

17 0.5 7. 10 7.24 1.59

17 1.5 2 14.93 14.53 2. 57

17 2.5 3 35.62 36. 12 5.60

14 3.5 4 62.50 59.50 7.73

13 4. 5 5 80.83 79.69 8.23

12 5.5 6 95.00 92.83 7.86

() 6.5 7 115.00 112.83 b. /2 5 7.5 8 122.50 122.00 7.07

4 8.5 9 125.00 129.50 7.50

23 1 Appendix 3c. Growth rate of razor clams at Graveyard Bar, Cordova Sector I.

Number Median Mean Standard in Age Ring Length Length Deviation Samele Years Number mm mm mm

25 0. 5 7.48 7.36 1.83

25 1.5 2 15.75 15.80 4.07

25 2. 5 3 34.06 34.60 6. 13

25 3.5 4 60.42 58.80 9.79

23 4.5 5 83.75 84. 17 13.58

22 5.5 6 I 05.00 104.50 11.46

22 6. 5 7 116.67 116 .77 9.59

20 7. 5 8 126.00 125.50 8.38

16 8.5 9 131 .25 130.44 7.65

9 9.5 10 13A. 25 135.89 5. 15

Appendix 3f. Growth rate of razor clams at Shag Rock. Cordova Sector I.

Number Median Mean Standard in Age Ring Length Length Deviation Sample Years Number !11111 111 111 mm

36 0. 5 6.40 6.50 1.2 1

1 36 1.5 - I (1 .88 16.3 1 3.5 1

36 2.5 3 35.00 36.58 8. 11

35 3.5 4 60.3 1 60.86 9.5 7

27 4.5 5 84.58 82.93 6.46

15 5.5 () I 03.75 I 00.67 9. 74

23 2 Appendix 3g. Growth rate of razor clams at Twin Rocks Gut ter. Cordova Sector 1.

Number Median Mean Standard m Age Ring Length Length Deviation Sam12Ie Years Number mm mm mm

30 0.5 6.27 6.40 1.50

') 30 1.5 4- 16.70 16.90 3.92

30 2. 5 3 33.71 35.20 7.78

30 3.5 4 57.99 63.50 16.27

30 4.5 5 85.00 88.83 I 5.68

30 5.5 6 I 08.75 I 07.67 13.89

29 6.5 7 ILi .)b I.W ..n::S I I .6Y

25 7.5 8 130.83 127.40 I I.99

18 8.5 9 134.00 132.00 13.02

9 9.5 10 137.50 134.22 14.74

Appendix 3h. Growth rate of razor clams at Blind Gutter off Big Point. Cordova Sector I.

Number Median Mean Standard in Age Ring Length Length Deviation Sample Years Number 111 !11 lll lll 111 !11

30 0.5 6.78 6.63 1.14

31 1.5 2 15.81 15.36 3.31

30 2.5 3 35.00 35.00 7. 26

30 3.5 4 64.38 64.50 l 1.0 I

28 4.5 5 l 0 I.25 97.00 13.32

33 5.5 6 I 21.07 l I 9.88 9.30

22 6.5 7 127. 14 126.54 7.52

233 Appendix 3i. Growth rate of razor clams at Canoe Pass Trail Bar, Cordova Sector 1.

Number Median Mean Standard in Age Ring Length Length Deviation Sample Years Number mm mm mm

103 0.5 6.38 6.31 1.96

101 1.5 2 22.62 24.37 7.61

93 2.5 3 39.72 44.35 13.65

84 3.5 4 67.43 69.93 16.05

72 4.5 5 99.25 97. 17 13.12

35 5.5 6 116.88 115.31 8.42

9 6.5 7 125.50 124.67 8.67

Appendix 3j . Growth rate of razor clams at Hartney Bay, Cordova Sector 1.

Number Median Mean Standard Ill Age Ring Length Length Deviation Sam pie Years Number m111 111111 mm

32 0.5 6.77 6.62 1.1 1

'1 32 1.5 - 16.79 16.53 4.02

32 2.5 3 36.36 35.44 6.05

"l') _) - 3.5 4 63.75 61.53 12.52

28 4.5 5 83.75 86.82 18.00

13 5.5 6 108.75 105.85 16.43

9 6.5 7 I 26.25 I 23.67 10.54

234 Appendix 3k. Growth rate of razor clams at Northeast Concrete Bar, Cordova Sector 1.

Number Median Mean Standard in Age Ring Length Length Deviation Sample Years Number mm mm mm

39 0.5 6.31 6.07 1.73

39 1.5 2 23.62 23.77 4.98

39 2.5 3 39.70 42.85 11.44

39 3.5 4 71.50 73.69 17.71

34 4.5 5 104.71 104.26 11.76 17 5.5 6 120.62 119.53 10.56

13 6.5 '/ Ul.�U 13l.Y2 �. lU 7 7.5 8 135.50 136.57 5. 18

2 8.5 9 145.00 146.00 3.00

,... L. 9.5 10 148.00 149.00 3.00

10.5 11 155.50 155.00

11.5 12 158.50 158.00

)

)

)

)

235 Appendix 31. Growth rate of razor clams at Little Mummy Island Bar, Cordova Sector 1.

Number Median Mean Standard in Age Ring Length Length Deviation SamE1e Years Number mm mm mm

127 0.5 6.21 6.16 1. 75

127 1.5 2 23.69 24.25 9.00

123 2.5 3 43.22 45.42 13.13

114 3.5 4 75.80 75.74 14.59

101 4.5 5 100.58 99.00 12.31

75 5.5 6 119.45 117.96 10.71

59 6.5 7 1:29.89 130. 1-1 8.90

23 7.5 8 138.50 137.78 6.96

14 8.5 9 143.99 143.21 7.39

7 9.5 10 151.25 149.86 5.39

2 10.5 11 151.00 155.00 8.48

236 Appendix 3m. Growth rate of razor clams at northeast corner of Big Mummy Island, Cordova Sector I.

Number Median Mean Standard in Age Ring Length Length Deviation Sam,ele Years Number mm mm mm

30 0.5 6.42 6.53 1.48

30 1.5 2 18. 12 17.83 5.18

30 2.5 3 35.91 36.83 6.12

30 3.5 4 68.00 68. 17 9.63

30 4.5 5 98.33 97.50 10.36

30 5.5 6 117.00 116.00 7.00

24 6.5 7 126.67 126.38 5.27

7 7.5 8 128.75 128.43 5. 15

Appendix 3n. Growth rate of razor clams at Erickson Bar, Cordova Sector 1.

Number Median Mean Standard In Age Ring Length Length Deviation Sam,ele Years Number mm mm mm

61 0.5 7.59 7.31 2.47

60 1.5 2 27.40 27.05 5.55 ) 57 2.5 3 48.50 49.68 11.77

54 3.5 4 76.60 77.67 10.12

51 4.5 5 99.32 99.53 8.62

) 41 5.5 6 116.31 115.71 7.70

21 6.5 7 124.38 124.00 7.06

4 7.5 8 133.00 129.50 9.33

2 8.5 9 127.00 131.00 8.48

237 Appendix 3o. Growth rate of razor clams at Shirttail Bar # 1, Cordova Sector 1.

Number Median Mean Standard in Age Ring Length Length Deviation Same1e Years Number mm mm mm

34 0.5 6.37 6.68 2.88

33 1.5 2 26.50 27.64 7.80

33 2.5 3 47.50 49. 18 13.38

26 3.5 4 79.60 76.65 13.34

24 4.5 5 98.50 98.62 10.80

10 5.5 6 113 .00 113 .00 3.16

4 6.5 7 120.00 122.00 3.46

Appendix 3p. Growth rate of razor clams at Shirttail Bar #3, Cordova Sector 1.

Number Median Mean Standard in Age Ring Length Length Deviation Sam12Ie Years Number mm mm mm

50 0.5 6.60 6.68 2. 18

50 1.5 2 18.60 18.70 4.43

50 2.5 3 36.25 37.90 9.09

50 3.5 4 60.62 62.70 10.86

50 4.5 5 85.00 87.30 10.12

50 5.5 6 I 06.43 104.70 9.60

49 6.5 7 114.8 1 114.86 7.89

43 7.5 8 122.50 122.35 6.85

31 8.5 9 128.41 128.77 6.79

15 9.5 10 129.64 130.67 5.62

238 Appendix 3q. Growth rate of razor clams at Copper Sands, Cordova Sector 2.

Number Median Mean Standard m Age Ring Length Length Deviation Sample Years Number mm mm mm

7 0.5 7. 10 6.57 1.50

7 1.5 2 16.88 16.29 3. 19

7 2. 5 3 36.25 35.57 8. 11

7 3.5 4 55.83 55.57 7.89

7 4.5 5 76.25 77.00 9.64

7 5.5 6 87.50 89.86 10.97

5 6.5 7 102.50 102.00 11.40

5 7.5 8 112.50 110.00 9.27

239 Appendix 3r. Growth rate of razor clams at Outside Egg Islands, Cordova Sector 2.

Number Median Mean Standard in Age Ring Length Length Deviation Sam12Ie Years Number mm mm mm

74 0.5 6.98 6.97 1.61

74 1.5 2 16.12 15.38 3.42

74 2.5 3 34.62 34.70 8.51

74 3.5 4 58.89 59.23 10.07

74 4.5 5 81.67 81.12 11.60

74 5.5 6 99.06 97.14 10.49

74 (), .) I" 7 109.69 1 0�.35 9.05

73 7.5 8 117.50 116 .66 7.60

63 8. 5 9 122.68 122.32 7.86

51 9.5 10 127.32 126.90 7.38

29 10.5 11 131.94 130.96 7.47

9 11.5 12 131.50 129.78 6. 71

240 Appendix 3s. Growth rate of razor clams at Grass Island, middle, Cordova Sector 3.

Number Median Mean Standard in Age Ring Length Length Deviation Sam_ele Years Number mm mm mm

9 0.5 6.35 6.00 1.83

9 1.5 2 15.83 15.89 4.88

9 2.5 3 34. 17 36.44 10.91

9 3.5 4 62.50 60.89 9.94

9 4.5 5 88.75 85.89 6.57

9 5.5 6 1 01.25 99.78 7.86

7 6.5 7 1 11.25 110.57 5. 15

4 7.5 8 115 .00 115.75 7.40

24 1 Appendix 3t. Growth rate of razor clams at Strawberry Reef, Cordova Sector 4.

Number Median Mean Standard in Age Ring Length Length Deviation Sample Years Number mm mm mm

86 0. 5 3.60 4.98 2.48

86 1.5 2 23.24 22. 58 10.16

83 2.5 3 48.04 46.22 11.96

82 3.5 4 71.84 70.05 13.92

73 4.5 5 90.58 88.64 12.33

60 5.5 6 I 04.50 I 03.08 10.92

46 6.5 7 113.116 112.98 10.30

40 7.5 8 120.45 119.62 8. 73

27 8.5 9 126.50 125.52 8.48

12 9.5 10 130.00 127.42 8.77

4 10.5 11 125.00 132.00 12.75

242 Appendix 3u. Growth rate of razor clams at Softuk Beach, Cordova Sector 4.

Number Median Mean Standard m Age Ring Length Length Deviation Sample Years Number mm mm mm

89 0.5 4.39 5.56 2.43

89 1.5 2 16.53 17.11 8.07

89 2.5 3 40. 14 39. 19 11.85

86 3.5 4 61.88 60.90 14.29

80 4.5 5 82.50 81.06 14.06

57 5.5 6 100.31 98.23 10.89

54 6.5 7 110.31 109.04 8.31

51 7.5 8 116 .62 115.72 7.06

47 8.5 9 120.92 120.19 5.96

28 9.5 10 125.91 125.21 5.21

13 I 0.5 11 127.92 127.00 4.38

4 11.5 12 130.00 130.75 4. 14

243 Appendix 3v. Growth rate of razor clams at northwest end Katalla Beach, Cordova Sector 4.

Number Median Mean Standard in Age Ring Length Length Deviation Sam121e Years Number mm mm mm

30 0.5 5.96 5.97 1.60

30 1.5 2 24.54 26. 17 7.54

30 2.5 3 53.75 50.33 9.78

30 3.5 4 75.83 73.83 15.26

30 4.5 5 95.00 92.83 12.93

30 5.5 6 105.38 104.50 10.33

JO 6.5 113. /.) 113 . .)0 l U. l2

30 7.5 8 117 .69 118.50 9.52

21 8.5 9 121.67 123.55 9.21

8 9.5 10 134.00 132.00 8.29

244 Appendix 3w. Growth rate of razor clams at middle of Katalla Beach, Cordova Sector 4.

Number Median Mean Standard in Age Ring Length Length Deviation Sam12le Years Number mm mm mm

56 0.5 4.8 1 4.93 1.67

56 1.5 2 22.08 25. 12 17.53

56 2. 5 3 45.62 45 . 39 13.53

56 3.5 4 70.00 69.86 17.32

56 4.5 5 90.67 88.96 14.51

56 5.5 6 104.28 102.54 11.71

52 6.5 7 112.27 111. 04 9. 17

29 7.5 8 120.38 119.33 7.7 1

19 8.5 9 121.50 120.29 6.74

245 Appendix 3x. Growth rate of razor clams at southeast end Katalla Beach, Cordova Sector 4.

Number Median Mean Standard m Age Ring Length Length Deviation Sam12Ie Years Number mm mm mm

31 0.5 5.88 5.61 1.72

31 1.5 2 21.56 21.03 6.40

31 2.5 3 40.50 37.97 12.34

30 3.5 4 63.33 59.67 17.26

24 4.5 5 80.00 75.75 21.66

18 5.5 6 97.50 92.83 18.93

16 6.5 7 I 0'2.50 99.50 14.14

14 7.5 8 I 07.50 I 05.21 7.99

9 8.5 9 105.83 105.61 5.66

Appendix 3y. Growth rate of razor clams at northwest end of Kanak Island outside beach, Cordova Sector 4.

Number Median Mean Standard m Age Ring Length Length Deviation Sample Years Number mm mm mm

37 0.5 6.53 7.22 3.07

37 1.5 2 25.28 27.40 8.65

37 2.5 3 47.08 48.28 12.38

37 3.5 4 67.08 69.64 16.54

27 4.5 5 88.64 91.54 13.53

22 5.5 6 104.00 I 04.95 13.97

13 6.5 7 117.00 116.04 10.26

5 7.5 8 117.50 116.50 7.48

246 Appendix 3z. Growth rate of razor clams at Kanak Island - middle of outside beach, Cordova Sector 4.

Number Median Mean Standard in Age Ring Length Length Deviation Sample Years Number mm mm mm 96 0.5 6.06 6.11 2.31

96 1.5 2 25.71 24.66 7.00

96 2.5 3 43.44 43.77 12.18

94 3.5 4 64.88 64.92 13.20

76 4.5 5 86.40 85.95 13.74

72 5.5 6 98.93 98.94 10.79

57 6. 5 7 109.32 I 09.24 9 . 00 36 7.5 8 115.62 115.33 7.95

12 8.5 9 121.67 122.42 6.60

247 Appendix 3aa. Growth rate of razor clams at Kayak Island, Cordova Sector 4. *

Number Mean Standard in Age Ring Length Deviation SamEle Years Number mm mm

34 0.5 6.06 3.35

34 1.5 2 28.44 6.03

34 2.5 3 54. 12 7.30

33 3.5 4 77.06 7.43

32 4.5 5 91.16 6.39

32 5.5 6 101.44 6.67

32 6.5 7 107.91 6.29

25 7.5 8 111.92 6. 16

25 8. 5 9 115.08 6.05

22 9.5 10 1 18.54 5.79

19 10.5 1 1 121.42 6. 13

14 11.5 12 121.93 5.55

10 12.5 13 121.90 5.86

4 13.5 14 122.00 7.35

*Data collected by Rae Baxter, June 26-28, 1960.

248 Appendix 3bb. Growth rate of razor clams at Dixon Harbor, Southeast Alaska.* Number Mean Standard in Age Ring Length Deviation Sam,ele Years Number mm mm

19 0.5 11.21 3.74

21 1.5 2 29.86 6.10

21 2. 5 3 47.67 9.12 21 3.5 4 64.05 7.99

21 4.5 5 81.57 6.92

21 5.5 6 92.62 6. 17

21 6.5 7 99.05 6.38

21 7.5 8 l 05.48 5.36

21 8.5 9 111.00 5.49 21 9.5 10 113.90 4.92

20 10.5 11 116. 15 4.92

20 11.5 12 I 18.15 4.69

18 12.5 13 120.00 4.78

6 13.5 14 1 22. I 7 6.88 4 14.5 15 121.50 7.77

3 15.5 16 126.00 6.56

2 16.5 17 128.00 8.48

17.5 18 124.00

18.5 19 125.00

*Data collected by Rae Baxter, July 22, 1960.

249 Appendix 3cc. Growth rate of razor clams at Nuka Island, southwest end, Outer District Cook Inlet.*

Number Mean Standard in Age Ring Length Deviation Sam121e Years Number mm mm

24 0.5 4.67 1.27

24 1.5 2 28.58 6.21

24 2.5 3 55.96 6.52

24 3.5 4 79.04 6.35

24 4.5 5 95.88 6.47

24 5.5 6 I 09.71 4.72

24 b.) I Ib.I.J2 ).56 21 7.5 8 120.05 5.62

17 8. 5 9 123.94 5.63

9 9. 5 10 129.00 3.50

3 10.5 II 133.00 3.60

11.5 12 138.00

12.5 13 139.00

*Data collected by Rae Baxter, April 18, 1962.

250 Appendix 3dd. Growth rate of razor clams at Augustine Island, lower Cook Inlet.*

Number Mean Standard in Age Ring Length Deviation Sample Years Number mm mm

25 0.5 8.24 5.12

37 1.5 2 28.49 7.05

37 2.5 3 52.76 7.84

37 3.5 4 72.81 8.70

37 4.5 5 88.86 7.45

37 5.5 6 101.19 6.38

37 6.5 7 108.89 6.00

36 7.5 8 112.97 6.80

18 8.5 9 120.89 5.02

14 9.5 10 124.71 3.58

10 10.5 11 127.80 5.63

9 11.5 12 129.78 4.15

,- 1 " 0 12.5 l.J 130.67 5.12

5 13.5 14 132.80 5.12

4 14.5 15 133.75 5.80

2 15.5 16 131.00 5.65

*Data collected by Rae Baxter during June, 1959.

251 Appendix 3ee. Growth rate of razor clams at Polly Creek Beach, west side Cook Inlet.

Number Median Mean Standard in Age Ring Length Length Deviation Samrle Years Number mm mm mm

115 0.5 6.03 6.20 2.62

115 1.5 2 25 .94 25.74 7.31

115 2.5 3 55.39 53.20 13.61

115 3.5 4 81.86 79.89 20.47

115 4.5 5 102.62 100.24 14.75

112 5.5 6 114.32 113.43 11.05

104 6.5 7 121.63 121.04 9.48

99 7.5 8 128.41 128.74 9.22

93 8. 5 9 134.88 ] 34.82 8. 61 58 9.5 10 138.08 137.95 8.21

32 10.5 11 142.86 142.62 9.49

15 11.5 12 143.57 143.17 9. 57

252 Appendix 3ff. Growth rate of razor clams at Swikshak Beach, Alaska Peninsula.

Number Median Mean Standard in Age Ring Length Length Deviation Sample Years Number mm mm mm

48 0.5 6.00 6.44 2.60

48 1.5 2 27.22 27.31 7.25

48 2.5 3 58.57 59.08 17.32

48 3.5 4 100.00 95.33 17.18

46 4.5 5 120.48 116.89 11.46

37 5.5 6 133.00 129.09 9. 18

22 6.5 7 142.50 139.04 10.19

17 7.5 8 149.38 146.71 7.95

11 8.5 9 155.42 151.54 8.91

4 9.5 10 145.00 149.50 10.31

3 10.5 11 157.50 153.67 8.49

253 APPENDIX 4. Method of total estimation for a stratified sampling scheme when two subestimates are combined within 1000 ft.2 (92. 9 m2) index blocks.

To obtain the desired estimates:

Let

L·1 = estimate (by total count) of the number of large clams in the i-th block,

= S·I estimate (by sampling) of the number of small clams in the i-th block,

X· counted number of small clams in the j-th sample (i.e., j 1, 2, 3, J = ... , 20) of 5 ft.2 2 Then the mean number, Xi, of small clams per 5 ft. for the i-th block will be: - 1 20 = X 20 L X· j-1 J 2 2 To obtain Si expand 5 ft. to 1000 ft. by using the factor of 200, i.e.,

S·1 = 200 X 1 · 2 where Si is expressed in terms of number of small clams per 1000 ft. with Si referring to the i-th block.

The variance of Si is given by: V(S ) (200)2 V'X ' i = \ jJ i.e., 2 2 [20(LX ) - (DI:j) ] V(Si) = (200) ? 2� (20)( 19) } If we let {

Ti estimate of the total number of clams for the i-th block Then

T·I = L·1 + S·I And

V(Ti) = V(Si) (given by above formula). This yields an estimate of the total number of clams, and the associated variance estimate, for each of the 1000 ft.2 blocks. To obtain a single estimate of clams per 1000 ft.2 by combining the estimates for the different blocks, some "weights" must be chosen for

254 APPENDIX 4. (continued)

the different tide level blocks. The weights will represent the relative importance of the different tide level types (e.g., if the +1 fo ot tide zone composes 50 percent of the total clam habitat, then the + 1 foot block would receive a weight of .50).

Let

Wi weight for the i-th block. (Note that weights must sum to 1) T weighted estimate of total (large and small) clams per 1000 ft.2 for the index area

Then

2:-W1· T· T . 1 1

where lhe · pro duels W 1 T1 's are summed for all blocks.

V(T) =

These estimates apply - in a statistical sense - oflly to the index area. Inference from ) the index area to the total beach falls outside the realm of statistics and must be made at the researcher's discretion.

)

)

)

)

255 ) APPENDIX 5. Gamma distribution fitted to Point Steele Beach " C " plot series razor clam abundance by tide level.

A general gamma distribution curve, Z = rtse-vt which is zero at t = 0 and where r, s, and v are positive constants, closely resembles the empirical data (Fig. 27, page 113).

Model :

Let

X be tide level (feet) and

Y be clam abundance

= Then, for X +4, +3, +2, . . . , -1, -2, ... , -200, ... the best fit of

= b -c(5 - X) y a (5 - X) e

is wanted whore a, b, u!lll c un: pu:sitivc coefficients. Taking natural logs of both sides realizes

loge (Y) = loge (a) + b loge (X - 5) - c (X - 5) This linear equation can be fitted by ordinary least squares (multiple regression) such that

where

X 1 loge (Y)

A loge (a)

X2 loge (5 - X)

x3 5 - x

The linear multiple regression will give estimates of b and c directly, and a = eA.

Therefore,

a = 465.909 b = 4.36842 c = 0.95596

Index of multiple correlation = 0.9876

Standard error of estimate 0.2238

256 APPENDIX 6. Analysis of substrates obtained from Cordova and Polly Creek razor clam growing areas.

257 Appendix 6a. Analysis of substrate obtained from Point Steele Beach, Hinchinbrook Island and Concrete Bar (Cordova Sector 1) August, 1971 at the mean lower low water tide level.

Percent materials passing through the respective screen

Point Steele Beach Concrete Bar Lab Lab Lab Lab Lab Number Number Number Number Number Screen Size 810 811 823 824 825

#4

#8 100 100

#10

f. # 1 100 100 #30

#40

#50 99.8 99 100 99.5 99.6

#80 21 23 62 56 66

# 100 6 7 35 31 37 #200 1.7 0.7 6.5 7.2 8.0

Particle Size Percent material according to hydrometer test

0.02 mm 1.8* 1.8* 2.8 3.0 2.3

0.005mm 1.2 1.5* 2.3 2.3 2.0

Approximate specific gravity

2.73 2.78 2.80 2.79 2.77

*See ex planation page 121.

258 Appendix ob. Analysis of su bstrate obtained from Canoe Pass Trail Bar and Big Point Bar (Cordova Sector 1) August, 1971 at the mean lower low water tide level.

Percent materials passing through the respective screen

Canoe Pass Trail Bar Big Point Bar Lab Lab Lab Lab Lab Lab Number Number Number Number Number Number Screen Size 807 808 809 819 820 821

#4

#8

#10 100

#16 100 100

#30

#40 100

#50 IOO 99.5 100 99 99 99

#80 77 81 77 30 34 26

#100 46 46 43 I3 I6 II

#200 8. 1 I0.5 6.3 3.0 3.9 1.7

Particle Size Percent rnaterial according to hydrometer test

0.02 mm 2.2 2.4 1.8 2.3 2.0 1.9*

0.005mm 1.8 1.8 1.8 1.6 1.6 1.6

Approximate specific gravity

2.73 2.72 2.73 2.73 2.75 2.77

*See ex planation in test on page 121 .

259 Appendix 6c. Analysis of substrate obtained from Inside Ocean Bar and Southwest Ocean Bar (Cordova Sector 1) August, 1971 at the mean lower low water tide level.

Percent materials passing through the respective screen

Inside Ocean Bar Southwest Ocean Bar Lab Lab Lab Lab Lab Lab Number Number Number Number Number Number Screen Size 812 813 814 815 816 817

#4

#8

#10

#16 100 100

#30 100

#40 100 99.7 99.5 100 100 100

#50 98 97 97 99.5 99.3 99. 1

#80 34 32 31 38 40 41

#100 17 17 15 15 17 18

#200 3.9 4.6 3.4 1.7 2.0 1.9

Particle Size Percent material according to hydrometer test

0.02 mm 2.4 2.6 2.3 1.9* 2.0 2.3*

0.005mm 1.8 2.3 1.9 1.6 1.6 1.6

Approximate specific gravity

2.75 2.76 2.77 2.75 2.72 2.72

*See explanation in test on page 121.

260 Appendix 6d. Analysis of substrate obtained from Shirttail Bar # 1 and Rockslide Bar (Cordova Sector 1) August, 1971 at the mean lower low water tide level.

Percent materials passing through the resrective screen

Shirttail Bar #1 Rockslide Bar Lab Lab Lab Lab Lab Lab Number Number Number Number Number Number Screen Size 826 827 828 829 830 83 1

#4

#8

#10

#16 100 100 100

#30 100 100 100

#40

#50 98 99 97.5 99.6 99.5 99

#80 39 42 37 62 64 61

#100 19 20 16 30 29 32

#200 3.4 3.6 2.7 5.9 5.7 8.5

Particle Size Percent material according to hydrometer test

0.02 mm 2.7 2.4 2.4 2.5 2.9 3.2

0.005mm 2.4 2.0 2. 1 2.0 2.4 2.4

Approximate specific gravity

2.71 2.71 2.68 2.76 2.74 2.74

26 1 Appendix 6e. Analysis of substrate obtained from Little Mummy Island Bar (Cordova Sector 1) March, 1970 at random between mean lower low water and the +4 foot tide level.

Percent rnaterials passing through the respective screens

Sample Sample Sample Sample Sampl� Sample Sample Sample Screen Size #1 #2 #3 #4 #5 #6 #7 #8

0.742 inch 100 100 100 100 100 100 100 100

#4 99.94

N #8 0\ N #20 99.93 99.99 99.99 99.99 99.99 99.99

#35 99.98 99.97 99.89 99.94 99.95 99.96 99.94 99.96

#65 86.97 87.52 86.67 86.63 87.23 87.27 87.19 87.33 #100 20.02 21.05 20.32 21.26 20.83 21.66 21.19 20.84 #150 5.48 5.39 5.35 5.22 5.19 5.29 5.19 5.29

#200 1.99 1.93 2.01 2.10 1.92 2.03 1.95 2.12

<#200 0.00 0.001 0.001 0.00 0.001 0.00 0.00 0.00 Appendix 6f. Analysis of substrate obtained from Katalla Beach and Softuk Beach (Cordova Sector 4) August, 1971 at the mean lower low water tide level.

Percent materials passing through the respective screen

Katalla Beach Softuk Beach

Screen Size Lab Number 818 Lab Number 822

#4

#8 #10

#16 100 100

#30 #40 99

#50 99.8 95

#80 46 36

#100 21 14.5

#200 2.0 1.2

Particle Size Percent material according to hydrometer test

0.02 mm 2.5* 2.0*

O.OU)inm 1.6 1.3*

Approximate specific gravity

2.72 2.70

*See explanation in text on page 121.

263 Appendix 6g. Analysis of Polly Creek Beach (Cook Inlet) substrate obtained September, 1970 from a razor clam growing area at unknown tide levels.

Percent material passing through the respective screen

Lab Lab Lab Lab Screen Size Number 803lf Number 804l/ Number 8053 I Number 806±/

318 inch 100

#4 100 99 100 100

#8 99.5 93 99.5 99.9

#10 99.2 90 99.5 99.8

#16 98 74 99 99.5

#30 86 35 93 97

#40 68 19 86 82

#50 39 7 72 39 #80 11 2 30 7

#100 6 18 4

#200 2.3 0.98 3.3 1.5

Particle Size Percent rnaterial according to hydrometer test

0.02 mm 1.8 1.1* 2.2 1.8*

0.005mm 1.8 0.8 1.8 1.5

Approximate specific gravity

2.76 2.73 2.73 2.74

1 I Sample was labeled "only small clams, no large clams." 21 Sample was labeled "many small clams, no large clams." 31 Sample was labeled "many large clams." 41 Sample was labeled "many large clams, no small clams."

*See explanation in text on page 121.

264 APPENDIX 7. Test results of razor clam growth increment in valve length by tide level.

265 Appendix 7a. An analysis of growth increment in valve length by tide level for razor clams at Little Mummy Island study plots, Orca Inlet, Cordova, Alaska, 196 9.

Comparative growth increment from the sixth to the seventh annulus for members of the 1962 year class collected from the +3 t<:> the -2 foot study plot tide levels.

Analysis of Variance

df Sums of Squares

Among means 4 212.7112

Within groups 29 671 .0536

Total 33 883.7648

212.7112/4 F = 2.2981 < F.95 (4, 29) = 2.70 671.0536/29

Comparative growth increment from the sixth to the seventh annulus for members of the 196 2 year class collected from the +2 nd the -2 foot study plot tide levels.

Mean increment at +2 = 10.3750 mm; Mean increment at -2 = 16.6250 mm

t = 2.6890, v14 > 2.14 t.95; < 2.98 t.99

Comparative growth increment from the first to the second annulus for members of the 1961 and 1962 year classes collected from the + 1 and -1 foot study plot tide levels.

Mean increment (weighted by age) at +1 = 14.5208 mm;

Mean increment (weighted by age) at -1 = 18.7688 mm

t = 2.6153, v17 >2.11 t.95; < 2.90 t.99

266 Appendix 7b. An analysis of growth increment in valve length by tide level for razor clams at Rockslide Bar study plots, Orca Inlet, Cordova, Alaska, 196 9.

Comparative growth increment from the fourth to the fifth annulus for members of the 1963 year class collected from the +2 to the -3 foot tide levels.

Analysis of Variance

df Sums of Squares

Among means 5 78.2385

Within groups 50 1248.7437

Total 55 1326.9822

78.2385/5 F = = 0.6265 < F.95 (5, 50) = 2.40 1248.7437/50

Comparative growth increment from the fourth to the fifth annulus utilizing composite age classes (unweighted).

Number Tide Levels Mean Increment in Sample

+2 23.45 20 +1 19.82 11 z 26.14 28 -1 26.00 36 -2 26.26 31 -3 28.78 18

Tide Levels

+2 versus +1 F = 1.1833 < F.95 (19, 10) = 2.78 +2 versus Z F = 1.4716 < F.95 (19, 27) = 1.99 +2 versus -1 F = 1.9347 > F.95 (19, 35) = 1.90; t = 1.54, v54 < t.95 = 2.00 +2 versus -2 F = 1.6984 < F.95 (19, 30) = 1.94 +2 versus -3 F = 2.6269 > F.95 (19, 17) = 2.24 ; t = 2.73, v36 > t.99 = 2.72

267 Appendix 7c. An analysis of growth increment in valve length by tide level for razor clams at Inside Ocean Bar study plots, Orca Inlet, Cordova, Alaska, 196 9.

Comparative growth increment from the fifth to the sixth annulus for members of the 1962 and 1963 year classes collected from the +2 to the -2 foot tide levels.

Analysis of Variance

df Sums of Squares

Among means 4 228.2538 Within groups 33 635.4567

Total 37 863.7105

228.2538/4 F = = 2.9634 > F.95 (4, 33) = 2.66 635.4567/33

Comparative growth increment from the fifth to the sixth annulus using individual tests.

Tide Level Mean Increment -n

+2 13.6666 6 +1 13.7500 8 z 14.9090 11 1 -I 20.4285 7 -2 17.0000 6

+2 versus -2 t = 1.46 vl0 < t.95 = 2.23

+1 versus -1 t = 3.19 v13 > t.99 = 3.01

268 APPENDIX 8. Method for determining fecunidty in razor clams.

I. Average diameter of a single ripe, unfertilized razor clam ova = 90 microns.lJ II. Specific gravity of a single ripe, unfertilized razor clam ova = 1.04. Jj III. Formula for the volume of a sphere =

IV. Volume of a sphere of water with a diameter of 90 microns

3 3 = j(3.I4159)( 45) = 38I ,703.I85 u JJ 3 3 V. 1000 u 11 per mm .if or I,OOO,OOO,OOO u per mm 21 VI. I ,000,000,000 u3 38I,703.I85 u3 = x = 0.00038I70 mm3 I mm3 X

VII. 1000 mm3 0.0003 8I703 mm3 = X = 0.0000003 8 CC .§_/ I cc X CC

VIII. I cc water = Ig ]_/ or 0.00000038 cc water = 0.00000038g

IX. Specific gravity of water = I.O

X. 0.00000038g water x g razor clam ova Specific gravity of I = Specific gravity of I.04 X = 0.00000039g

XI. Average weight of ripe unfertilized razor clam ova = 0.39ug .21 XII. 0.00000039g Weight loss g = 1 razor clam ova x razor clam ova

As determined by W. P. Breese, Associate Professor of Fisheries, Oregon State 1J University, personal communication. 2/ u3 = cubic microns u = microns lJ4/ mm = millimeters mm3 = cubic millimeters JJ6/ cc = cubic centimeters g = grams 2.,/JJ ug = micrograms

269 APPENDIX 9

LIFE TABLES

The following life tables contain estimates of survival rates for each particular cohort utilizing survival rates as presented in Table 43, page 139. Data for the Orca Inlet tables are mainly from study plot information except as otherwise indicated; and data from Katalla and Softuk are from a combination of digging and screening. All sampling was done in a stratified manner except for the 1971 index tide level data for large clams, i.e., age 3 and older.

Ages 1 to 5 are considered to be prerecruit stock, therefore any levels of fishingmor tality would be applied after age 5 estimates.

It should be remembered that the following life tables were not constructed in the conventional manner (Quick, 1960) due to the superfluous nature of the latter. Also, each age-class survivorship corresponds roughly to the conventional Sl,x value, give or take a month or two.

270 Appendix 9a. Estimated yield of razor clams from Little Mummy Island Bar (northeast side) for 1000 feet of beach width between the -3 and the +3 foot tide levels with no fishing mJrtality (from study plot data).

Year Oass 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970

Year Frequency by Age Oass

s s 10/ 8/ ]_/ _§_/ Jj _j_/ )_/ 1969 lll62 I 54 2.115 4 -323 1077 508 800 446 246 1192 11 S* NS** 1970 25 62 62 129 43 1 203 320 178 98 28 0 1_1 I 1971 10 25 25 52 172 81 128 71 8 0 0 11 ? � j_/ N 1972 4 10 10 21 69 32 51 29 6 2 0 0 --.] -

1973 2 4 4 8 28 13 20 11 6 --

1974 1 2 2 3 11 5 8 5 3 0 0 Jj

1975 0 1 1 1 4 2 3 2 1 0 0 0 ·--

? 1976 0 0 1 2 1 1 1 0 0 0 0 1977 0 1 0 1 0

1978 0 0

1979

1980

S* Indicates that substrate was screened for these estimates. NS** Indicates that no screening was done.

Appendix 9c. Estimated yield of razor clams from Canoe Pass Trail Bar (on east side of bar) for 1000 feet of beach width between the -3 and the +3 foot tide level with no fishing mortality (from study plot data).

Year Oass 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970

Year Frequency by Age Oass

s s �I Jj jj Jj 5.1 ]_/ Jj Jj 1969 15 119 371 534 172 127 534 1074 s 1/ 1970 6 48 148 -�214 69 - 51 160 97 -3356 S*

1971 2 19 59 85 28 I 20 64 29 302 ll135 62 N -.) w 1972 1 8 24 34 11 8 91 1220

1973 0 3 9 14 4 3 36 366 .21 1974 1 4 5 2 1 14 146 .21 1975 0 2 2 1 1 2 1 6 59 I 1976 1 1 0 0 1 0 2 23

1977 0 0 0 1 9

1978 0 4

1979 1

1980

*S indicates that substrate was screened for these estimates. Appendix 9d. Estimated yield of razor clams from Shirttail Bar #1 (opposite Shirttail Point) for I 000 feet of beach width between the -3 and the +3 foot tide level with no fishing mortality (from study plot data).

Year Oass 1961 1962 1963 1964 1965 1966 1S67 1968 1969 1970

Year Frequency by Age Oass

NS NS* / 5/ 3/ �I Jj £ il 11 ll 1969 32 96 193 -434 64 -225 ? ? s 5/ 1970 13 38 77 174 - 26 90 ll212 01 S** I 5/ 1/ 1971 5 15 31 69 10 l - 36 1908 -3265

N 1972 2 6 12 28 4 14 I 572 294 -.) .j:>. 1973 1 2 5 11 2 6 ? I 229 88

1974 0 1 2 4 1 2 ? 92 35 I Jj 1975 0 1 2 0 1 371 14

1976 0 1 0 15 6

1977 0 6 2

1978 2

1979 1 0

1980 0

* NS indicates that no screening was done. ** S indicates that substrate was screened for these estimates. Appendix 9e. Estimated yield of razor clams from Southwest Ocean Bar (in bight) for 1000 feet of beach width between the -3 and the +3 foot tide levels with no fishing mortality (from study plot data).

Year Oass 1962 1963 1964 1965 1966 1967 1968 1969 1970

Year Frequency by Age Oass

s s Jj .§./ ]j Jj ll 1969 596 1608 Jj17 74 2107 568 0 s 1970 238 643 710 170 0 ll13 057 S*

1971 95 257 284 0 1175 ll 0

1972 38 103 114 lJJ 0 353 0 1973 15 41 45 53 54 11 141 0

1974 6 16 18 21 22 4 0 0

1975 2 7 7 9 9 2 0 Jj 0 1976 1 3 3 3 3 0 9 0

1977 0 0 0 4 0

1 1978 0 0 1 0

1979 0 0 0

1980 0 0

*S indicates that substrate was screened for these estimates.

275 Appendix 9f. Estimated yield of razor clams from Inside Ocean Bar (in line with Twin Rocks and the Rockslide on Hawkins Island) for 1000 feet of beach width between the -3 and the +2.5 foot tide level with no fishing mortality (from study plot data).

Year Oass 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970

Year Frequency by Age Oas�

s s �I 7/ 4/ / 2_1 Jj ]_ Jj ll 1969 729 -2065 2550 �2793 -364 1579 121 5829 s 5/ 1970 292 826 1020 -146 632 36 525 ll5738 4 S*

1971 117 330 408 447 58 14 157 5164 ll1815 3

1972 47 132 163 179 23 Jj 6 63 1550 1634 - . N -..l 0\ 1973 19 53 65 72 9 40 2 620 490 � 5/ 1974 7 21 26 29 4 16 I - 248 196 1975 3 8 10 11 1 6 0 4 99 1 Jj 78

1976 1 3 4 5 1 3 2 40 31

1977 0 1 2 2 0 1 1 16 12

1978 1 1 1 0 0 6 5

1979 0 0 0 3 2

1980

1981 0 0

*S indicates that substrate was screened for these estimates. Appendix 9g. Estimated yield of razor clams from Rockslide Bar (opposite the rockslide on Hawkins Island) for 1000 feet of beach width between the -3 and the +3 f)ot tide levels with no fishing mortality (from study plot data).

Year Oass 1958 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970

Year Frequency by Age Oass

s s 5 2. .§_/ -/ 1969 11_/29 1227 Jj571 798 425 jj11 7 11 73 1114 6 Jj 0 s 1970 12 91 228 319 170 t__=J47 29 44 0 1.1 0 S* 1971 5 36 91 128 68 19 I 12 13 0 0 1.1 0 N -..l -..l 1972 2 15 37 51 27 7 5 0 0 1973 1 6 15 20 11 3 2 0 0

1974 0 2 6 8 4 1 1 Jj 0 0

1975 1 2 3 2 0 0 0 0 0 I Jj 0

1976 0

1977 0 1 0

1978 0

1979

1980

*S indicates that substrate was screened for these estimates. Appendix 9h. Estimated yield of razor clams from Northeast Concrete Bar (laying within a line from the rock quarry to Bluff Point) for 1000 feet of beach width between the -3 and the +3 foot tide levels with no fishing mortality (from study plot data).

Year Oass 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970

Year Frequency by Age Oass

s s 12/ / 10/ 8/ 7/ 6/ 5/ 4/ 1 ll Jj ]_! Jj 1969 -48 0 -4 8 0 242 242 l94 l 798 242 0 0 0 s 1970 19 0 19 0 97 97 78 319� 97 0 0 0 Jj 0 S* 5/ 1971 8 0 8 0 39 39 31 128 39� - 0 0 0 0 Jj 0

N 1972 3 0 3 0 15 15 12 51 15 0� 0 0 0 0 -..J 00 1973 1 0 1 0 6 6 5 20 6 0 0 0

1974 0 0 0 0 2 2 2 8 2 0 0 0

1975 1 1 1 3 1 0 0 0 "'- 1976 0 0 0 1 0 0 0 0 0 0

1977

1978 0

1979

1980

*S indicates that substrate was screened for these estimates. Appendix 9i. Estimated yield of razor clams from Katalla Beach, 1971 for 3 miles of beach width between the -3 and the +4 foot tide levels with no fishing mortality.

Year Oass 1961 1962 1965 1966 1967 1968 1969 1970

Year Frequency by Age Oass

s S* 10/ 9/ 6/ 3/ 1971 67415 67415 33961 Jj339 6 1 3396 1 41011 660 20531J 50

1972 26966 26966 13584 13584 123198 18482

1973 10786 10786 5434 5434 5544

1974 43 15 43 15 2174 2174 2174 221� 1975 1726 1726 869 869 869 869 J.j 887

1976 690 690 348 348 348 348 3154 355

1977 276 276 139 139 139 139 1262 142

1978 110 110 56 56 56 56 505 57

1979 44 44 22 22 22 22 202 23

1980 18 18 9 9 9 9 81 9

1981 7 7 4 4 4 4 32 4

1982 3 3 1 1 13

1983 1 5

1984 0 0 0 0 0 0 2 0

1985

1986 0

*S indicates that substrate was screened for these estimates.

NOTE: Yield estimates for ages 3 to 1 0 are considered low.

279 Appendix 9j. Estimated yield of razor clams from Softuk Beach, 1971 for 1 1/2 miles of beach width (center of area lying opposite the tree-grass transition) between the -3 and +4 foot tide level with no fishing mortality.

Year Oass 1963 1964 1965 1966 1967 1968 1969 1970

Year Frequency by Age Oass

s S* 8/ ]_/ _§_/ 5/ 4/ 3/ 2/ 1/ 1971 65463 0 0 132846 0 l32846 53 1581 1249334

1972 26185 0 0 53 138 159474 112440

1973 10474 0 0 21255 0 63790 33732

1974 4190 0 0 8502 0 13493

1975 1676 0 0 3401 0 3401 5397

1976 670 0 0 1360 0 1360 4082 2159

1977 268 0 0 544 0 544 1633 864

1978 107 0 0 218 0 218 653 345

1979 43 0 0 87 0 87 26 1 138

1980 17 0 0 35 0 35 104 55

1981 7 0 0 14 0 14 42 22

1982 3 0 0 6 0 6 17 9

1983 0 0 2 0 2 7 4

1984 0 0 0 0 3

1985 0 0 0 0

1986 0

*S indicates that substrate was screened for these estimates.

NOTE: Yield estimates for ages 3 and 8 are considered low.

280 Appendix 9k. Estimated yield of razor clams from Big Point Bar, Orca Inlet, Cordova, Alaska, 1971, for 2850 linear feet of exploitable habitat at the west side of the gutter, starting at the entrance, with no fishing mortality.

Year Oass 1961 1962 1963 1964 1965 1966 1967 1968

Year Frequency by Age Oass

10/ 9/ 8/ 7/ 6/ 1971 3909 5864 l9546 5864 1955 Jj 0 il 0 1119 55

1972 1564 2346 7818 2346 782 0 0 782

1973 626 938 3127 938 313 0 0 313

1974 250 375 1251 375 125 0 0 125

1975 100 150 500 150 50 0 0 50

1976 40 60 200 60 20 0 0 20

1977 16 24 80 24 8 0 0 8

1978 6 10 32 10 3 0 0 3

1979 3 4 13 4 2 0 0 2

1980 2 5 2 0 0

1981 0 2 1 0 0 0 0

1982 0 0

1983 0

281 Appendix 91. Estimated yield of razor clams from Canoe Pass Trail Bar, Orca Inlet, Cordova, Alaska, 1971, for 2250 linear feet of exploitable habitat from base of easterly spit bearing westerly towards "Nat"*, with no fishing mortality.

Year Oass 1962 1963 1964 1965 1966 1967 1968 1969 1970

Year Frequency by Age Oass

9/ !}_/ 6/ Jj 3/ ]j 1 /** 1971 9350 0 Jj 0 93 50 0 9350 0 l8701

1972 3740 0 0 3740 1683

1973 1496 0 0 1496 505

1974 598 0 0 598 202 5/ 1975 239 0 0 239 0 0 239 0

1976 96 0 0 96 0 0 96 0 �32

1977 38 0 0 38 0 0 38 0 13

1978 15 0 0 15 0 0 15 0 5

1979 6 0 0 6 0 0 6 0 2

1980 2 0 0 2 0 0 2 0

1981 0 0 0 0 0 0

1982 0 0 0 0 0 0 0 0

* Nat is a horizontal control station established on a rock bluff prominence between Canoe Pass Trail and Canoe Pass.

** Considered to be a low estimate.

282 Appendix 9m. Estimated yield of razor clams from Inside Ocean Bar, Orca Inlet, Cordova, Alaska, 1971, for 1850 linear fe et of exploitable habitat starting at a point in line with Twin Rocks and the rockslide on Hawkins Island, working westerly with no fishing mortality.

Year Oass 1960 1961 1962 1963 1964 1965 1966

Year Frequency by Age Oass

11I 10/ 9/ 8/ Jj 6/ 5/ 1971 23648 0 35471 ll824 0 ll824 11824

1972 9459 0 14188 4730 0 4730 4730

1973 3784 0 5675 1892 0 1892 1892

1 974 1513 0 ?770 7')7 0 7C:,7 7')7 1975 605 0 908 303 0 303 303

1976 242 0 363 121 0 121 121

1977 97 0 145 48 0 48 48

1978 39 0 58 19 0 19 19

1979 15 0 23 8 0 8 8

":! 1980 6 0 9 3 0 3 -'

1981 2 0 4 0

1982 0 2 0 0 0 0

1983 0 0

1984 0

283 APPENDIX 10. Expansion of variance equations given on page 169 and presentation of a propagation of error formula to obtain greater accuracy in the calculation of the variance of the mean Vy.

The variance of T is:

and individual tide level estimates will have variances

2 *V-y + * V(PJ) + covariance terms.

The propagation of error formula is:

A ( 2 2N *(standard error of the mean number Vy 2 � (Decimal equivalent of % clams showing)) of clams per 5 frames per transect) ( ) 2 + 2N * mean number of clams per 5 frames per transect *Variance of the decimal (Decimal equivalent of % clams showing)2 equivalent of % clams showing

+ covariance terms.

284 GLOSSARY OF TERMS

Annulus - an annular growth ring; an-annulus; the laying down of close calcium formations in the valve indicating a decline or cessation of growth increment due to suspended feeding and/or cold water months.

Ecological genetics - deals with adjustments and adaptations of wild populations to their environment.

Ha bitat - attitude type - a razor clam bearing substrate which may assume an immense variety of exposures, i.e.: windward to or in the lee of prevailing winds; on the in-curve or out-curve of tidal currents; fed by slow tidal flows or by tidal bores; restrictive locations such as at the head of protected tidal gutters or nonrestrictive locations as on surf-swept breaker beaches; fast draining to slow draining; fine to coarse particulate stmcture; steep to shallow gradient; subject to rapid or slow annual accretion and degradation; strong localized eddies to absence of eddy effect; near fresh water drainage to several miles from fresh water drainage.

{pngth - thP ]Pngth nf th P r: wnr rl�m v�lvPs �s mP�smPrl in �ntPrinr- pnstPrinr rlirPrtinn ; the long dimensions of the valve.

Mouse Bioassay - supernatant liquid removed from a centrifuge of a mixture of blended clams and hydrolchloric acid are injected peritoneally into specific strains of mice. Duration of time from injection to death determines the level of P.S.P. Results are described by the number of micrograms of toxin per 100 grams of clam meat, i.e., ug/1 OOg.

P.S.P. - refers to paralytic shellfishpo isoning which is reputedly caused by the dinoflagellate Gonyaulax. If levels of the toxin are high within the clam, death to the human consumer may result, specifically by respiratory paralysis.

Sexual dimorphism - refers to the occurrence of two forms of individuals of the same cohort, irregardless of gender, whose average sizes and growth rates differ significantly, reflecting adequal rates of sexual maturity.

Show - also called apparent abundance due to the fact that not all razor clams that are present at a particular area cause themselves to be detected at the same time. The siphon of the razor clam is the detection mechanism which produces the show. Normally, when feeding, the tentacles of the incurrent and excurrent siphon lay nearly flush upon the substrate surface, indicating that the main body of the razor clam is close to the surface. When the tide ebbs, usually the razor clam will withdraw the tip of the siphon beneath the surface. As the bar continues to drain the razor clam withdraws its siphon more causing a depression or hole to form in the sand. This hole or depression is called "show".

When clams apparently suspend feeding and burrow to deeper depths before the bar drains there will be little or no evidence of show.

At other times a portion of the siphon may extend above the substrate surface. After the bar has drained to a certain degree the razor clam becomes locked in the substrate due to its inability to burrow in the now not fluid sand. Evidence of the siphon above the surface is not in conformance with the term "show" and would more correctly be termed "exposure".

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288 1931. Oam pack makes substantial gain, p. 165-166. -In Pac. Fish. Yrbk., 29(2), Consolidated Publishing Company, Seattle.

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- · ---=::--=-.,.,. 1933. Canned clams, p. 139-140. In Pac. Fish. Yrbk., 31(2), Consolidated Publishing Company, Seattle.

---=:c--:--:-· 1934. Canned clams, p. 147- 148. In Pac. Fish. Yrbk., 3 2(2), Consolidated Publishing Company, Seattle.

1935. Oam canning attains added stability in 1934, p. 155-157. In Pac. Fish. Yrbk., 33, Consolidated Publishing Company, Seattle.

----==---=-· 1936. Pacific clam canning advances sharply in 1935, p. 173-175. In Pac. Fish. Yrbk., 34, Consolidated Publishing Company, Seattle.

--=::--::--:-: ' - 1938. Pacific clam canning, p. 256-259. In Pac. Fish. Yrbk., 36, Consolidated Publishing Company, Seattle.

--,.,.---· 1941. Oams, p. 277-278. In Pac. Fish. Yrbk., 39(2), Consolidated Publishing Company, Seattle.

-· ------,::::-- 1942. Oams, p. 249-250. In Pac. Fish. Yrbk., 40(2), Consolidated Publishing Company, Seattle.

----==--"'..,-· 1943. Canned clams, p. 271-273. In Pac. Fish. Yrbk., 41(2), Consolidated Publishing Company, Seattle.

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---==---. 1945. Pacific clam canning, p. 279-284. In Pac. Fish. Yrbk., 43(2), Miller Freeman Publications, Inc., Seattle.

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-�,.---· 1947. Oams, p. 213. In Pac. Fish. Yrbk., 45(2), Miller Freeman Publications, Inc., Seattle.

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