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.