FEASIBILITY of ARTIFICIAL REEFS in INTERTIDAL WATERS by Andre

Home , Artificial reef, English sole

FEASIBILITY OF ARTIFICIAL REEFS IN

INTERTIDAL WATERS

Andre DeGeorges

A Thesis

Presented to The Faculty of California State University, Humboldt

In Partial Fulfillment

of the Requirements for the Degree

Master of Science

December, 1972 FEASIBILITY OF ARTIFICIAL REEFS IN INTERTIDAL WATERS

Andre DeGeorges

Approved by the Master's Thesis Committee

Chairman

Approved by Graduate Dean TABLE OF CONTENTS Page ACKNOWLEDGEMENTS ABSTRACT ii LIST OF TABLES iv LIST OF FIGURES vi INTRODUCTION 1 Study Plan 3 Prior Studies 3 DESCRIPTION OF STUDY AREAS 5

Humboldt Bay 5 Southport Channel 6 Fields Landing Wreck 7 Arcata Small Boat Basin 7 MATERIALS AND METHODS 12

Southport Channel 12 Fields Landing Wreck 16 Arcata Smalls Boat Basin 17

Fish Collections 17 Benthos 17 Plankton 18 Analysis of Data 18 RESULTS 28 Southport Channel 28 Fish Fauna 28 Attaching Organisms 28

Siltation 36 Page

Fields Landing Wreck 36 Arcata Small Boat Basin 36 Kinds and Numbers of Fish 36

Species of Potential Sport Fishing Interest 55 Seasonal Occurrence by Species 59

Kinds and Numbers of Invertebrates 59 SOURCES OF ERROR 68 Southport Channel 68 Fields Landing Wreck 69 Arcata Small Boat Basin 70 IMPLICATIONS FOR FISHERIES MANAGEMENT 71 Southport Channel 71 Fish and Invertebrates...... 71

Siltation 73

Fields Landing (A Simulated Intertidal Artificial Reef) 74 Pros and Cons of Intertidal Reefs 74 Future Utilization of Artificial Reefs in

Humboldt Bay 74 Arcata Small Boat Basin (Potential Intertidal Reef Site) 75 Species of Fish 76 Invertebrate Fauna 76 RECOMMENDATIONS 77 LITERATURE CITED 78 APPENDICES 83 ACKNOWLEDGEMENTS

I am greatly indebted to Dr. George H. Allen for bringing the subject of intertidal reefs to my attention and to the City of Arcata for their continued interest in the project. Editorial assistance and recommendations by Dr. Allen, Dr. Boger A. Barnhart, and Dr. M. J. Boyd were particularly helpful in writing this thesis. I would also like to thank Fred Glassey and Dr. John Demartini for their assistance in the identification of invertebrates. Thomas Lambert's identification of subtidal artificial reef invertebrates was greatly appreciated.

A large number of fellow students assisted in hook and line fishing, beach seining and in placement of reef structures. To all of these individuals, I extend my deepest thanks, especially to Jim Walker, Vic Tanny, and the Over-the-Hill boys. The California Cooperative Fisheries Unit provided space for construction and storage of experimental reefs, and aided in their placement in Humboldt Bay. ii

ABSTRACT Studies were undertaken in 1972 on the potential of artificial reefs in intertidal waters of Humboldt Bay, northern California. Underwater observations were made of two types of "low profile" reef structures, made of car tires, placed near an existing reef located in Southport Channel of South Humboldt Bay. Fish populations around an old shipwreck in intertidal waters of Hookton Channel in South Humboldt Bay were enumerated by sampling with rod and reel and by direct underwater observations. The "low profile" structure I designed proved effective in attracting fish and producing growth of attaching organisms. The structure was not subject to excessive siltation. The shipwreck attracted transient fish populations, with fish entering the area on the incoming tide and leaving on the out- going tide. Over-fishing an intertidal reef is probably more difficult than depleting subtidal reefs which develop a more resident population of fish. Fishing intertidal and subtidal reefs should result in greater fishing success if fishermen can be directed to them at times when seasonal abundance of fish are the greatest. Fish and invertebrates were studied at a proposed site for an intertidal fishing reef in a newly excavated small boat basin near the City of Arcata, located on North Humboldt Bay. Fauna was sampled over a nine month period using beach seines, plankton nets, and benthic grabs. I found evidence that nine species of fish spawn and that the larvae and juveniles of these species feed and grow for extended periods of time in the area. The larvae and juveniles of another eight species, presumably having spawned elsewhere, migrated iii into the vicinity of the basin to feed and mature. Overlying waters of the basin were abundant with plankton. Benthic fauna was low in diversity but high in numbers of individuals. The design of the artificial reef tested in Southport Channel would presumably be unsuitable to the Arcata Small Boat Basin due to a high siltation rate from the surrounding mud flats into the boat basin. iv

LIST OF TABLES

Page

1. Seine hauls for which catch figures were actual counts

and those involving estimation of catch from sub-

sampling (February-September, 1972) 19

2. Results of tests for independence of subsamples of

organisms taken in beach seine hauls at low tide in the

Arcata Small Boat Basin (April-September, 1972) 22

3. Example of calculations used in determining the number

of individuals per species in beach seine hauls 24

4. Chi-square tests to determine if there was a significant

difference between the number of species of fish and in-

vertebrates taken in seine hauls at low and high tide 26

5. Summary of observations made while diving on experimental

units and main reef structures of Southport Channel (May-

September, 1972) 29

6. Growth of attaching organisms on experimental units and

main reef structures of Southport Channel (May-September,

1972) 32

7. Number and species of fish caught and hours fished by

students with rod and reel on Fields Landing Wreck (Fall,

1971- March, 1972) 38 Page 8. Summary of underwater observations made on Fields Landing Wreck (June-September, 1972) 40

9. Number of fish collected in beach seines fished at low tide in the Arcata Small Boat Basin (February-

September, 1972) 41

10. Number of fish collected in beach seines fished at high tide in the Arcata Small Boat Basin (February-

June, 1972) 44

11. Number of fish collected in gill nets fished over a six hour tidal cycle in the Arcata Small Boat Basin (January-August, 1972) 47

12. Number of invertebrates collected in beach seines fished at low tide in the Arcata Small Boat Basin (January- September, 1972) 60

13. Number of invertebrates collected in beach seines fished at high tide in the Arcata Small Boat Basin (February-June, 1972) 63

14. Number of invertebrates collected by Eckman Dredge in

the Arcata Small Boat Basin (April-August, 1972) 65

15. Classification of invertebrates, by method of feeding,

collected in the Arcata Small Boat Basin 92 vi

LIST OF FIGURES

Page 1. Map of Humboldt Bay showing the general location

of study areas .... 2

2. Fields Landing Wreck, Hookton Channel, South Humboldt

Bay, at low and high tide 8

3. Map of the Arcata Small Boat Basin indicating the approximate area swept by the beach seine and where gill

nets were generally set 9

4. Arcata Small Boat Basin in June, 1972 at a -2.2 low

tide and in August, 1972 at high tide 10

5. low profile artificial reef structure, (PL), (March 1,

1972) 13

6. Low profile artificial reef structure, (AD), (January 14, 1972)

7. Sample splitter used to subsample fish and invertebrate

fauna collected from the Arcata Small Boat Basin 21

8. Copper rockfish, (Sebastodes caurinus), observing diver

off AD structure (July, 1972) 31

9. Underwater photograph of AD structure covered with the

hydrozoan, Obelia borealis (August, 1972) 33 vii Page

10. Underwater photograph of PL structure showing scant

growth of attaching organisms (May, 1972) 34

11. Underwater photograph of the AD structure showing the hydrozoan, Obelia borealis, and barnacle, Balanus

crenatus (August, 1972) 35

12. Breeding rock crabs, Cancer productus, on the AD

structure (June, 1972) 37

13. Number of surf smelt taken at low tide by beach seine in the Arcata Small Boat Basin (February-September,

1972) 51

14. Number of Pacific herring taken at low tide by beach seine in the Arcata Small Boat Basin (February-Sept-

ember, 1972) 52

15. Number of shiner perch taken at low tide by beach seine in the Arcata Small Boat Basin (February-

September, 1972) 53

16. Number of northern anchovy taken at low tide by beach seine in the Arcata Small Boat Basin (February-Sept- ember, 1972) 54

17. Number of staghorn sculpin taken at low tide by beach seine in the Arcata Small Boat Basin (February-Sept-

ember, 1972) 56 viii Page

18. Number of jacksmelt taken at low tide by beach seine in the Arcata Small Boat Basin (February-

September, 1972) 57

19. Number of topsmelt taken at low tide by beach seine in the .Arcata Small Boat Basin (February-

September, 1972) 58

20. Number of mysids taken at low tide by beach seine in the

Arcata Small Boat Basin (February-September, 1972) 66 INTRODUCTION

In 1971 the City of Arcata with funds from the California Com- mission on Small Craft and Harbors, dredged a sixty-foot wide channel to connect the .Arcata Channel to a small-boat basin excavated just west of the county landfill dump (Figure 1). The purpose of this construction project was to allow citizens access to North Bay, previously unavailable except through Eureka or Samoa boat landings. Montgomery (1971) reported on the feasibility of placing a fishing pier in the small boat basin by the City of Arcata based on a review of the literature. Montgomery identified potential sites for the placement of a pier, a fish-cleaning facility, and artificial reefs to increase the attraction of fish to the area. This plan forsaw much use of such pier fishing as the demand for places to fish increases. Pier fishing avoids the expense of boats or elaborate gear and is thus available to all segments of the community. Increased sport fishing is occurring in all of Humboldt Bay. The use of artificial reefs in different intertidal environments may be a management technique to assist in maintaining quality fishing for those fishermen who enjoy near-shore fishing. To obtain a better understand- ing and to realize the impact of artificial reefs in intertidal waters, extensive knowledge of the natural history of the fish in these waters should be examined before and after the placement of reefs. This will allow an assessment of the practicality of reefs in near-shore environments. The study presented in this paper examines the potential of artificial reefs to attract fish to intertidal environments in Humboldt Bay. 2

Figure 1. Map of Humboldt Bay,showing the general location of study areas. Study Plan My original experimental design called for the placement of artificial reefs in two intertidal channels located within the limits of the City of Arcata which extend southward into Humboldt Bay. Due to delay in receiving construction permits for works located in such intertidal areas, we could not proceed quickly with the placement of the reef. An alternate plan was adopted involving studies at three locations in Humboldt Bay: Southport Channel; Fields Landing; and a

small-boat basin located on the mud flats just west of the county landfill dump (Figure 1). The general objectives of studies at these three sites were as follows. In Southport Channel a subtidal reef of car tires already exists (DeWees 1970). I designed a "low profile" structure made of tires for use in intertidal waters. This structure was placed next to a unit of tires based on the configuration of the existing reef. Comparisons were made on the attraction of fish, attachment of organisms, and the rate of siltation between these structures.

It Fields Landing an old ship wreck (hull structure) lies in intertidal waters and sirmilates an intertidal reef. The kinds and numbers of fish found on this wreck could indicate the effectiveness of artificial reefs placed in other intertidal environments. The Arcata Small Boat

Basin is a potential site for artificial reefs. A knowledge of fish

and other fauna now in the area can aid in the future evaluation of

effectiveness of such structures to attract fish.

Prior Studies

An artificial reef may be described as any object placed in an underwater environment in order to increase the attractiveness of the 4 area to fish. The purpose generally is to improve the fishery of an area. The attraction of fish to sunken objects has been recognized by the Japanese for centuries as indicated by Oren (1968) in his extensive review of the literature. Prince (1972) and Lambert (1972) present current literature in reports of their studies on the attraction of certain fish and invertebrates to subtidal artificial reefs in Humboldt Bay. Design and construction of artificial reefs have been noted by Weeks (1972), Stone (1970) and Edmund (1967); however, these all deal with subtidal reefs. Very little is known of the ecology of the intertidal channels and mud flats along the perimeter of the Bay (University of Washington 1955), although a variety of studies have occurred in and around Hum- boldt Bay, some touching upon this environment Allen (1964) studied fishes in near-shore waters between Trinidad Head and the Eel River but did not include Humboldt Bay proper. Pierce (1965) studied fish in Humboldt Bay by seine hauls every two hours over a twenty-four hour period. Smith (1967) concentrated on embiotocid fishes of Hum- boldt Bay. Sopher (1969) performed a 12-month trawl survey of fishes in Arcata Bay. Porter (1964) studied larval flatfish off Humboldt Bay. Eldridge (1970) studied larval fish within Humboldt Bay, and Gore (1971) studied copepods from North Humboldt Bay. Keller (1963) studied the growth of eel grass, while Waddell (1964) examined the effects of commercial oyster culture on the eel grass beds. Thompson (1970) studied the physical characteristics of the Bay. Comparative studies of other west coast estuaries include those by Haertel and Osterberg (1967), Messersmith (1966) and Herald and Simpson (1955). DESCRIPTION OF STUDY AREAS

Humboldt Bay Humboldt Bay is located 40°451 north latitude, 124° west longi- tude. It is a coastal lagoon, 14 miles long and a maximum of 4 miles wide, impregnated by deep channels. It is separated from the ocean by two long narrow spits. The following description of the bay is from data presented in Allen (1964), Skeesick (1963) and Thompson (1970). Study plots are located in two sections of the bay: North Humboldt Bay near the City of Arcata (one study area) and South Humboldt Bay (two study areas). Humboldt Bay is characterized by a large tidal prism; on the average 44% of the mean high high tide volume being flushed into the ocean. Be- cause of this flushing, there is considerable mixing of the water column and a great influence by the oceanic water conditions. This mixing is characterized by nearly vertical salinities and isotherms. Salinities have varied between 28% in the winter (rainy season) to 1 34% in the summer. The water temperature varies between 3-18 C. Is a result of the high flushing rate, and upwelling of water along the adjacent coast considerable amounts of nutrients are carried into the Bay. Georgraphically, North and South Bays may be divided into tidal flats, channels and salt marshes. The predominant topographic feature of both bays are the tidal flats. These flats may be subdivided into two morphological units, high and low flats. The high flats grade bay-

1Data provided by the California Department of Fish and Game of thermograph records for instruments located in North Humboldt Bay. ward from an elevation of 4-4.5 feet adjacent to the shoreline to about the level of mean low low water (EM). The lower flats are those flats situated at or below MLLW. The high tidal flats are barren with the exception of the algal mats which cover these flats during the late spring and summer. The lower flats are characterized by eel grass (Zostera marina) beds. Higher flats predominate in Arcata Bay while lower flats predominate in South Bay. Both bays are traversed by channels. Four main channels carry tidal waters to and from Arcata Bay: Mad River Slough Channel, North Point Channel, Arcata Channel, and Bracut (Middle)Channel. Depths range from 3-4 fathoms in the lower reaches of the bay to 1-2 fathoms in the upper reaches. Southport and Hookton Channels are the two main channels draining South Bay. Depth variations are about the same as the channels in Arcata Bay.

Salt marshes once covered an estimated 8 square riles in Humboldt Bay. An estimated 80-90% of these former marshes have been eliminated

as a result of diking to create agricultural land filling to provide solid ground for roads and railroads. Elevation of salt marshes range from 5.5-7.0 feet above MLLW. In most places these marshes are separated from adjacent tidal flats by 2-3 foot wave-cut cliffs. Present marshlands are being gradually destroyed by wave action. Humboldt Bay appears to be losing its marshlands such as reported for other areas of

California (60% of the California estuaries destroyed as reported by Frey et al. 1970).

Southport Channel :Artificial Reef Southport Channel is one of the two main channels in South Humboldt Bay. It is primarily a mud and sand bottom environment, approximately twenty-five feet in depth. This channel is scoured by strong tidal currents resulting in extremely heavy siltation. My artificial reef structures were placed just off the northwestern end of an existing artificial reef located in and paralleling Southport Channel (Figure 1).

Fields Landing Ship Wreck An old ship hull is located about seventy-five feet southwest of a small-boat launching ramp at Fields Landing, in Hookton Channel, South Humboldt Bay (Figure 1). It lies in water varying from three to ten feet at various tidal levels. The wreck is positioned in an east-west direction perpendicular to the channel. The upper section of the wreck is always partially exposed and is almost completely exposed at low tide (Figure 2). From the edge of the channel, the wreck extends another 50-75 feet into the channel where the hull remains submerged at all tidal levels.

Arcata Small Boat Basin The Arcata Small Boat Basin is about one-hundred and fifty feet at its widest point during a minus -1.0 foot tidal level (Figure 3). Depending on the tidal fluctuations depth may vary from zero to seven feet (Figure 4). Parallel to the Old Arcata Wharf is a dredged channel which leads from the Arcata Small Boat Basin into Arcata Channel. Shal- low mud flats surround the channels and basin and produce high rates of siltation during outgoing tides. The mud flats of this area are of a clay silt or silty clay texture consisting of 45-60% clay, 40-55% silt and 5% sand (Thompson 1970). This area is dynamic. Sides of the dredged channel have already sloughed inward making navigation hazard- ous, especially at low tidal levels. Thompson (1970) indicates the 8

Figure 2. Fields Landing Wreck, Hookton Channel, South Humboldt Bay at low and high tide. 9

Figure 3. Map of the Arcata Small Boat Basin indicating the approximate area swept by the beach seine and where gill nets were generally set. 10

Figure 4. Arcata Small Boat Basin on June, 1972 at -2.2 low tide and in August, 1972 at high tide. 11

seasonal erosion and deposition of sediments nullify each other. During the winter months wave action, as a result of northerly winds, causes net erosion in Arcata Bay. From late spring, summer and into the fall months, when southeasterly winds are predominant, Arcata

Bay is sheltered from wave action which results in net accretion.

The filamentous algal mats present during the late spring and summer may also add to net accretion (Thompson 1970). MATERIALS AND METHODS

Southport Channel

In 1968 Daniel Gotshall (employed by the California Department of Fish and Game) in cooperation with the Eureka Kiwanis Club, placed a tire reef in Southport Channel (DeWees 1970). The reef was made of

"low profile" tire units joined together by polypropylene line. I constructed a similar "low profile" unit (PL), as described by Prince

and Lambert (1972) (Figure 5). In addition I designed a modified tire unit (AD) for use in the Arcata Small Boat Basin (Figure 6). One PL and one AD structure were placed adjacent to the main reef in South- port Channel for comparative stud.

The PL unit was constructed of nine tires stacked side by side.

A hole was drilled through each side of all tires. Re-enforcement bar

was run through the tires, one through each set of holes, and bent back-

wards. Finally., a hole was drilled through the top of each tire and a

number-ten can of cement was placed in the bottom of each tire. This

weighted the structure and allowed air to escape the tires when placed

in the water, letting the reef sink slowly to the bottom.

The idea for the design of the AD structure came as a result of

my diving observations while taking underwater photographs for my

fellow graduate students on the artificial reef in Southport Channel. It soon became evident to me that the fish tended to inhabit mainly

the openings of the structures. In that case there may be four to

five feet, if not more, of potential habitat which is not utilized by

the fish, with the exception as a place of retreat. The unit I de- 13

Figure 5. Low profile artificial reef structure, (PL), (March 1,1972). 14

Figure 6. Low profile artificial reef structure, (AD), (January 14, 1972). 15 signed, therefore has an increased number of openings per unit area, in hope of increasing the population of fish that might inhabit the reef.

The AD unit consisted of a rectangular cement base structurally designed so that it had the strength of a cement floor (Figure 6). The base had welded re-enforcement bar criss-crossing its entire length, overlying chicken wire. The welded re-enforcement bar pro- truded perpendicularly out of the cement base, with three rods on each side of the base and one rod on each end. Holes were drilled through the top and bottom of the tires, and two tires were placed on each piece of re-enforcement bar. Two tires were placed across the top of the structure and the rebar bent back to form a three- dimensional rectangular configuration.

The AD and PL structures were carried to their placement sites by a pontoon boat belonging to the CSUH Foundation. The AD structure was set on two greased two-by-fours nailed to a plywood board. Tire irons were used to lever the AD structure into the water. The PL structure, because of the nature of its design, could be rolled off the boat.

A total of seven dives were made to study these reefs beginning on May 5, 1972 and ending on September 3, 1972. Observations were conducted by SCUBA and underwater photography. Notes were taken with a grease pencil on a plexiglass slate. A systematic survey was made by counting fish along the upper tires and then the lower tires of the AD reef. Counts were then made on the PL reef. Separate counts were made of fish which swam about the two structures. After this initial survey, observations were made of the attachment of organisms, siltation 16

and of any other appropriate phenomena. Photographs were taken with

a Nikonis, using a close-up attachment and flash attachment. Photos were taken randomly of anything which might appear relevant to the

study or for later verification of recorded observations.

Fields Landing Wreck

Fish populations were studied through the combination of fishing with rod and reel, creel census, and underwater observations with

SCUBA.

A creel census box was placed at Fields Landing Boat Ramp in mid-

February, 1972. To the box were attached two water-proofed forms :

one form explained the project and the other form provided instructions

on how to report fish caught. Attached to the box was a pencil and

a booklet to aid the fishermen in identification of their catch (Miller,

Gotshall and Nitsos 1965). The box and a sign were attached to a steel pole which was cemented into the ground. The sign read "Fishermen

You Can Help Improve Near Shore Fishing. Fields Landing Wreck Attracts

Fish. Fill Out The Enclosed Creel Census Forms." The first com- pleted form received was signed "Aldo Leopold." By mid-March of 1972,

the sign was ripped off the metal post, and the pencil and identification booklet stolen. A short time later the box was virtually torn

apart. Only two valid forms were received, one by a CSUH student.

Consequently, voluntary creel census was replaced with a rod and reel

survey using voluntary student help, and personal SCUBA surveys.

SCUBA surveys were only possible when clearer water occurred in the

summer and early fall months. 17

Arcata Small Boat Basin

An effort was made to obtain an overall picture of the animal

communities in the intertidal channel and mud flats represented by

the Arcata Small Boat Basin (Figures 3,4). Preliminary sampling was undertaken in January, 1972. From February through July bi-monthly

surveys were conducted, except for single surveys in August and Sep- tember. Details of the study method employed follows. Fish Collections. A beach seine was used to collect fish. The

seine was 23 meters long, with wings 8 meters long and a bag length of

6 meters. The width of each wing was 3 meters and that of the bag 7 meters. Mesh size (stretched length) of the wing was 34 mm, and of the bag 10 mm. The seine was set from the bow of a fourteen foot motor boat.

The seine was set in a semi-circle about 33 meters from the landing

ramp. The setting of the net and its return to shore averaged ten

minutes. The area swept by the net was about 50 square meters.

A variable mesh-gill net was used to sample the overlying waters

for fish. The net was 3.7-meters deep with mesh sizes (stretched

length) between 10 mm and 37 mm. The net was set to sample half of

a tidal cycle, usually from low to high tide. Initially, the net was set immediately at the west end of the boat ramp and run in a north-

easterly direction. Midway through the nine month sampling period, sets were made across the "Dredged Channel" at the mouth of the boat

basin (Figure 3).

Fish collected by seine and gill net were preserved in 10-20%

formalin and taken to the university for further identification and

enumeration.

Benthos. A Ponar Dredge was used initially. The weight of the 18 dredge buried the instrument deep into the soft substrate. Conse- quently, it was discarded in favor of the lighter Eckman Dredge.

The Eckman dredge, though originally designed for use in fresh water, functioned adequately in soft bottom shallow marine environments(Hedg- peth 1957). Data taken from the dredge were examined qualitatively.

Quantitative information was gained from beach seine hauls.

Plankton. Samples were collected with a #17 plankton net having a mouth one-quarter meter in diameter, and nylon mesh approximately

.076 mm in diameter. Two tows were made on any one sampling date, in opposite directions along the same track of the "Dredged Channel". Each tow lasted about five and one-half minutes. Since the plankton net was not fitted with a flow meter, only relative abundance of species could be reported. Analysis of Data. Roedel (1953), Clemens and Wilby (1961), and

Miller et al. (1965) were used in the identification of fish. Common names are used for fish throughout this report and follow those in Bailey et al. (1970). Scientific and common names are listed in Ap- pendix IV. Light et al. (1967) was used in the identification of invertebrates. Plankton were identified by unpublished plates(2) and by Newell and Newell (1963).

Early in the study seine hauls caught relatively few animals so that all animals were counted by hand (Table 1). When large numbers of juveniles and larvae of fish and invertebrates began to show up in the catches, individual counts became impossible. I tried to obtain

(2)Plates supplied by Dr. George Crandell, Dept. Oceanography, CSUH, from drawings made while at Oregon State University. 19

Table 1. Seine hauls for which catch figures were actual counts and those involving estimations of catch from subsampling (February-September 1972).

Date of Actual Estimates of Relative Seine Haul Count Catch from Subsamples 2-4 x 2-25 x 3-10 x 4-8 x 4-22 x 5-7 x 5-28 x 6-24 x 7-6 x 7-27 x 8-19 x 9-16 x 20

a representative subsample for counting. First, I assumed that gallon jars containing unsorted specimens might be representative subsamples of the seine haul, since each species theoretically had an equal and likely chance of being placed in a given jar. A chi-square test for independence demonstrated that the jars were unrepresentative subsamples.

There are several possible causes for this bias. Heavier organisms may collect at the rear of the seine. Fish with poor swimming ability may be caught first. Also, during initial sorting students may tend to pick out the larger or more interesting specimens.

A second subsample method was to take a gallon of animals after the entire catch was thoroughly mixed in a wash tub. A chi-square test showed that subsamples varied considerably in kinds and numbers of organisms and were not representative of the catch in the seine hauls.

Next, I designed a sample splitter. Larval and juvenile sample splitters of Webb and Noble (1966) were too costly, so I designed a sample splitter which was inexpensive (Figure 7). 1 list of seine hauls sampled by this method is given in Table 1. Only in the haul of May

7, 1972 were subsamples independent (representative)(Table 2). A comparison of subsamples showed that the order of species ranked by abundance remained relatively the same. As was expected, the order of ad- jacently-ranked species fluctuated slightly from subsample to subsample.

Because I could not find a method to obtain independent subsamples from hauls with high numbers of individuals, I utilized the data from

all subsamples from each haul to estimate the total number of each species taken in a haul as follows:

For species with more than 100 individuals in a subsample, 100 individuals per subsample were weighed and the mean weight per individual 2

Figure 7. Sample splitter used to subsample fish and invertebrate

fauna collected from the Arcata Small Boat Basin. 22

Table 2. Results of tests for independence of subsamples of organisms taken in beach seine hauls at low tide in the :Arcata Small Boat Basin (April-September 1972).

Date of Sampling

4/22 5/7 5/28 6/13 6/24 7/27 8/19 Number of Subsamples 4 2 4 4 4 2 2 Chi-square Calculated 1000 10.8 >200 83.4 >100 *1 *1

(C-1)(R-1) 1 Degrees of 30 8 33 24 33 1 * Freedom

Chi-square * * Tabulated 43.5 15.5 4 36.4 44 1 1 Alpha, .05

Randomness no yes no no no *1 *1

1By this time it had been determined that the subsamples taken from the splitter were dependent. Therefore, the determination for independence was terminated. 23

of that species was calculated for each subsample. For a species represented by less than 100 individuals in a subsample, the total number was counted and its mean weight per individual was calculated for each subsample. The mean weights for each species in a seine haul were totalled and an average taken. This represented the average weight of one individual of a given species in the seine haul

(Table 3, D). Next, I totalled the weights that a particular species constituted in each subsample (combined subsample weights, Table 3, A). The percent by weight for each species was determined by dividing the combined subsample weight by the total weight of the subsamples (Table 3, B). The percent weight for a particular species times the total weight of the seine haul estimated the weight of that particular

Species in the haul (Table 3, C). This estimated weight divided by the weight of one individual of that species gave an estimate of the total number of individuals for the given species in the seine haul

(Table 3, E).

Total lengths and sexual maturity of fish were taken from a single haul each month.

Because of the lower numbers of fish taken in gill nets, it was possible to count and measure lengths of all fish.

Sorting and counting animals required many tedious man hours of work. Therefore, I needed to know whether it was worth the time and effort to sample at both high and low tides. A contingency table was set up and a chi-square test run to test the hypothesis that there was no difference between the species of both fish and invertebrates taken at high and low tides (Table 4). The test indicated no differ- Table 3. Example of calculations used in determining the number of individuals per species in beach seine hauls.

Combined Percent Estimated weight _Average Estimated number subsample weight of species in weight in of individuals weight in sub- seine haul. (B x grams of a in seine haul. (grams) samples. weight of seine single in- Species haul: 17,396). dividual. A B C D E Surf Smelt 220 5 870 0.52 1673 Herring 129 3 506 0.36 1405

Anchovy 1080 24 4239 2.57 1650 Staghorn Sculpin 2398 54 9420 7.79 1209 Starry Flounder 75 2 296 37.1 8

English Sole 158 4 619 9.0 69 Shiner Perch 254 6 998 17.1 56

Shiner Juvenile 12 0.3 47 2.0 24 Longfin Smelt 932 0.2 35 3.1 11 Salmon 10 0.2 41 5.1 8

Pholis ornata 0.8 0.02 3 0.8 4 Crago 51 1.2 200 1.3 154

Table 3. (continued)

Species A B C D E

Aglaja 0.8 0.02 3 0.025 125 Polynoidae 0.25 0.006 1 0.07 14 Gammarid 0.05 0.001 0.2 0.05 4

Gemma gemma 0.05 0.001 0.2 0.05 4 2

Livoneca calif. .65 0.02 3 0.09 35 5 Beetle: Fresh Water 0.1 0.002 0.4 0.1 4 Mysid 0.5 0.01 2 0.03 58 0.07 Corophium 0.15 0.003 0.6 9 Debris 30.4 --- ______---

Total Weight of subsamples1 4431

1Equals the sum of (A)

Table 4. Chi-square tests to determine if there was a significant difference between the number of species of fish and invertebrates taken in seine hauls at low and high tide.

Date of Number of Species Haul 1970 Fish Invertebrates High Low High Low Tide Tide Combined / Tide Tide Combined 2-4 9 9 18 13 10 23 2-25 5 9 14 3 8 11 3-10 6 10 16 9 10 19 4-8 10 17 27 3 12 15 4-22 10 12 22 2 9 11

Combined 40 57 97 30 49 79

Calculated

x2fish :1.21 x2 invertebrates : 8.49

Tabular

2x .05,9 4d.f.: 9.4 27 ence between the number of species caught at high or low tide, and that only the number of animals caught varied. Therefore, as noted previously, sampling at high tide was discontinued during the latter stages of this study. RESULTS

Southport Channel

Detailed observations on the seven dives I made to study the PL and AD reefs in Southport Channel are listed in Appendix I. The major findings are summarized in Table 5.

Fish Fauna. I observed five species of fish on the PL and AD reefs: copper rockfish, black rockfish, kelp greenling, white surfperch, and pile perch. In addition, another three species of fish were observed on the main reef: spotfin surfperch, ling cod, and striped surfperch. The AD structure had a resident population of 5-8 copper rockfish, while the fish within the PL structure were transient. Their numbers varied from dive to dive. Territorial behavior was exhibited on the AD structure: copper rockfish continually swam out in groups of three or four to investigate the intruding diver (Figure 8).

Attaching Organisms. Three predominant organisms were found attached to the PL and AD reefs: a hydrozoan, Obelia borealis Nutting,

1901; an encrusting tunicate, Didemnum cranulentum Ritter and Forsyth,

1917, and a barnacle, Balanus crenatus Bruguiere, 1789 (Table 6). The hydrozoan (Obelia borealis) covered the entire AD structure giving it the appearance of an "underwater shrub" (Figure 9). In contrast, the

PL structure was virtually devoid of the hydrozoan (Figure 10). It was not until settling of barnacles occurred that the PL structure began to equal the AD structure in the number of attached organisms. Barnacles replaced the hydrozoans as the predominant attaching organism on the AD structure (Figure 11).

It appeared that the abundant growth of hydrozoans on the AD -Table 5. A Summary of observations made while diving on experimental units and main reef structures of Southport Channel (May-September, 1972).

Date Number & Kinds of Number & Kinds of Attachment of Dive Fish on AD Structure Fish on PL Structure of Organisms Siltation General

May 5 8-10 copper rockfish Initially none-later PL:minimal growth Minimal No observations 8-10 juvenile black 5 juvenile black of the hydrozoan made. rockfish rockfish Obelia borealis, and encrusting tunicate Didenum cranulentum

AD:Obelia borealis pre - dominantes; reef appears as "Underwater shrub"

May 26 _AD predominates in number of AD:Hydrozoans so thick Minimal Visibility poor,

fish inhabiting, qualitative can barely see first live rock 2 only due to lack of air through tires; fish crab observed on 9 forced to utilize AD reef upper portion of structure

June 1 5 copper and 5 black rockfish PL:Growth increased Tires of AD No observa- yearling black rockfish hover slightly on PL due & PL filled tions made. over both AD & PL structures to settling of barn- to their low- acle, Balanus crenatus er rims. with silt AD:Growth of barnacle on AD not as great, due to already dominant hydrozoan Table 5. (continued)

Date Number & Kinds of Number & Kinds of of Dive Fish on AD Structure Fish on PL Structure Attachment Organisms Siltation General

June 22 AD:8 copper rockfish PL:2 copper & 2 black No change No change rock crab ob- rockfish served breeding on AD structure

July 28 AD:6-8 copper rockfish PL:Mainly juvenile black AD:barnacles be- No change Cearest water swim out to investi- rockfish coming domin- yet experienced. gate diver. Schools ant. Hydrozoan Visibility 6-8 of white surfperch & dying out ft. (main reef) juvenile black rockfish school of spotfin hover over both structures. surfperch, young- Pile perch & three pound of-the-year black black rockfish rockfish recruited August 3 No change No change Second settling of No change Nothing barnacles. Hydrozoans still hanging on in

interior of AD reef 30

August 12 No change No change No change No change School(main reef) of 20-30 recruited young-of-the-year black rockfish, Groups of pile perch, schools of white surf perch and yearling black rockfish

September 3 No change No change No change No change Adult & young-of- the-year striped surfperch seen for the first time (main reef) 31

Figure 8. Copper Rockfish, (Sebastodes caurinus), observing diver off AD structure (July, 1972). 32

Table 6. Growth of attaching organisms on experimental units and main reef structures of Southport Channel (May-September, 1972)

Type of Units

Experimental Units Main Reef Structures

AD1 PL2 PL3 4 HP

Date of mid- Early Existing Existing Placement January March

Major ypicalbserved In Hydrozoan Very Very Hydrozoan Heavy Little Little Heavy May

Major Fauna Hydrozoan- Barnacles Barnacles Hydrozoan- Observed In Barnacles Barnacles September

1Prototype low profile structure being tested for possible use in the intertidal waters of the _Arcata Small Boat Basin.

2Single tire unit, typical of the main reef, placed next to and compared to the AD reef.

3The typical low profile reef placed in 1968 as described by Prince and Lambert (1972). . 4 eHigh profile structures placed by Prince in the summer of 1971 33

Figure 9. Underwater photograph of the AD structure covered with the hydrozoan, Obelia borealis (August, 1972). 34

Figure 10. Underwater photograph of PL structure showing scant growth of attaching organisms (May, 1972). 35

Figure 11. Underwater photograph of the AD structure showing the

hydrozoan, Obelia borealis, and barnacle, Balanus crenatus

(August, 1972). 36 structure was conducive to the breeding of the rock crab, Cancer productus

Randall, 1839 (Figure 12). Breeding was observed only once on the PL structure, but I observed rock crabs breeding on two different occasions while diving on the AD structure.

Siltation. Siltation affected both structures. The PL structure, because the tires were in direct contact with the substrate, was affected more than the ID structure. The cement base of this structure kept the tires off the bottom. Even so, tires two feet above the bottom were filled to their lower rims with sediments.

Fields Landing Wreck Fish taken by rod and reel on Fields Landing Wreck from the fall of

1971 through June 13, 1972 are listed in Table 7. Observations on four dives made on the wreck during the summer of 1972 may be found in 'Appendix II and are summarized in Table 8. Hook and line fishing was at its best during the fall, winter, and early spring months. By late spring the catch per-unit-effort decreased.

Underwater observations indicated that during the summer months the shallow often-exposed section of the wreck is inhabited primarily by the juveniles of black rockfish and striped surfperch., The subtidal section of the wreck contained a more resident population of black rockfish.

Arcata Small Boat Basin

Kinds and Numbers of Fish. Kinds and numbers of fish taken at low tides by beach seine hauls are listed in Table 9, and at high tide in

Table 10. Fish taken by gill net are listed in Table 11. A discussion of size of fish caught and possible explanation of time of occurrence of fish may be found in Appendix III. 37

Figure 12. Breeding rock crabs, Cancer productus, on the AD structure

(June, 1972). Table 7. Number and species of fish caught and hours fished by students with rod and reel on Fields Landing

Wreck (Fall, 1971-March, 1972).

Date of Fishing 1 Species Caught 19712 1972 Fall - Dec. 1-4 1-22 2-14 3-1 3-12 3-17 3-27 4-16 4-30 5-13 Striped Surfperch - - 24 31 23 1 3 3 10 3 8 2

White Surfperch - 1 - - 3 - - - - - 2 -

Walleye Surfperch - - - - 2 ------1 38 Pile Perch - - - - 2

Redtail Surfperch ------1 2 - - 9 6

Copper Rockfish 1 ------

Black Rockfish - 2 ------

Ling Cod - 1 - -

Capezon - - 1 ------

Kelp Greenling ------1 1 - - - -

Staghorn Sculpin - - - - 1

Jacksmelt 5 15 Table 7. (continued)

Date of Fishing 2 Species Caught_ 1 1971 1972 4-16 4-30 Fall — Dec. 1-4 1-22 2-14 3-1 3-12 3-17 3-27 5-13 Number of Fishermen 1 2 6 2 3 1 2 1 1 8 6 5

3NR Time Fished In Hours NR3 NR3 1 2 1 1 3 1 2 1.5 2

3 Catch Per Hour NR3 NR3 NR 31 15 1 4 2 10 1.5 16 18 39

1See Appendix IV for scientific names. 2Specific dates not available. Data from personal interview. 3Data not recorded. Table 8. Summary of underwater observations made on Fields Landing Wreck (June-September, 1972).

Date of Dive Observations of Fish June 22 1. No schools of surfperch or jacksmelt were observed. 2.Juvenile black rockfish seen. 3.Two spotfin surfperch seen in the exposed section of the wreck. Subtidal section: schools of 2-6 lb. black rockfish, a few copper rockfish.

June 29 1. No schools of surfperch or smelt were observed. 2. Submerged portion of wreck: 20 black rockfish, a few speared weighing 1-1/2 lb. - 4 lb. 4 0 August 12 1. Juvenile black rockfish feed on algae on exposed section of wreck. 2.5 lb. black rockfish in shallow section of wreck. 3.10-20 black rockfish on submerged portion of wreck.

September 3 1. Two 5 lb. black rockfish and one 5 lb. ling cod in the exposed section of the wreck. 2. Schools of juvenile black rockfish and striped surfperch. Table 9. Number of fish collected in beach seines fished at low tide in the Arcata Small Boat Basin (February-September, 1972).

of Seining Date Species 3-10 4-22 5-7 5-28 6-24

7-6 7-27 8-9 9-16 3 Total S.05 2-25 4-8 6-21 4 % Staghorn Sculpin 345 102 307 104 160 1209 - 47 8 243 32 *6 2557 5.2 Y

Juvenile Surf Smelt 967 1777 3263 4461 13 1673 - - 38 - - - 20992 43.0 Y

Juvenile - - - W/Sp Herring - 3 1238 8555 1 1405 0 7 1 11210 23.0 4 1 Shiner Perch Male ------70 33 586 33 78 800 1.6 Su

Shiner Perch Female 0 3 61 45 142 56 0 298 183 586 7 162 1543 3.2 Sp/Su

Shiner Perch Juvenile - - - - - 24 0 181 26 4896 355 1959 7441 15.2 Su

Walleye Surfperch ------21 92 14 - 15 142 0.3 Su

White Surfperch ------24 13 47 3 0 87 0.2 Su

Topsmelt - - - 5 11 9 211 1 2 137 - - 376 0.8 Sp/Su

Jacksmelt - - - 6 4 10 32 0 - - - - 52 0.1 Sp/Su Table 9. (continued)

Species Date of Seining 5 Caught 2-25 3-10 4-8 4-22 5-7 5-28 6-21 6-24 7-6 7-27 8-9 9-16 Total3 % S.0.

N. Anchovy Larvae ------13 332 345 0.7 Su

N. Anchovy Juvenile - - 3 35 18 1650 - 67 51 34 40 73 1971 4 Sp/Su

N. Anchovy Adult ------87 39 - - 25 151 0.3 Su 4

Saddleback 2 Gunnel - 2 2 19 2 4 0 96 7 *6 21 *6 153 0.3 Y

Snake Prickle- back - - 3. ------1 0.002 0

Arrow Goby 1 3 9 ------13 0.03 W

Finscale Goby - - 108 26 131 • 1 - 1 - - - - 267 0.5 Y

English Sole Juvenile 134 99 77 56 31 69 - 34 7 14 - - 521 1.06 Y

Bay Pipefish - 2 2 - 4 1 - 2 2 17 - 23 53 0.1 Y

Black Rockfish------13 3 - - - 16 0.03 Su Table 9. (continued)

Date of Seining Species 43%Total Caught 2-25 3-10 4-8 4-22 5-7 5-28 6-21 6-24 7-6 7-27 8-9 9-16 S.0.5 Tom Cod ------0 0.0 0 Silver Salmon 2 - 1 ------5 0.01 0 King Salmon 1 ------1 0.002 0 Longfin Smelt 4 72 - 17 - 11 - 6 6 - - - 110 0.2 Y Speckled

Sanddab - - 1 ------1 0.002 0 4 3 Sand Sole ------0 0.0 0

Starry Flounder 10 8 6 - 3 10 - 2 4 108 5 7.7A 163 0.3 Y American Shad ------2 - - 1 - 3 0.006 0 Brown-Smooth- hound - 2 - 1 2 5 - - 10 0.02 Su TOtal2 10270 2080 5093 13338 529 6138 243 960 550 6687 511 2674 49087 1Plankton tow. 5 Seasonal Occurrence: Y, found over the entire sampling period; W, winter; Sp, spring; 2 Total number of fish collected in each seine haul. Su, summer; 0, occasional. 6 3 Total number f fish collected for a given species. Observed in catch but did not appear in sub-samples. 4 The percent which a species comprised of the total number of individuals for all seine hauls. Table 10. Number of fish collected in beach seines fished at high tide in the Arcata Small Boat Basin (February-June, 1972).

Date of Seining

Species Caught 2-4 2-25 3-10 4-8 4-22 6-13 Total1 % 2 S.0.3 Staghorn Sculpin 8 1 4 43 6 7 69 2.0 Y Juvenile Surf Smelt 588 947 515 25 36 1 2112 69 Y Juvenile Herring - 0.3 1 246 6 9 262 8.5 W/Sp

Shiner Perch Male - - - - - 11 11 0.36 Su 4 4 Shiner Perch Female 0.3 - - - 17 8 25 0.8 Sp/Su Shiner Perch Juvenile - - - - - 41 41 1.3 Su Walleye Surfperch - - - - 1 21 22 0.7 Su Su White Surfperch - - - - - 4 4 0.1 Top smelt ------Sp/Su Jacksmelt - - - 3 1 - 4 0.13 Sp/Su N. Anchovy Larvae ------Su N. Anchovy Juvenile - - - 0.5 6 374 381 12.3 Sp/Su N. Anchovy Adult ------Su Table 10. (continued)

of Seining Date Species Caught 2-4 2-25 3-10 4-8 4-22 6-13 Total1 %2 S.0.3 Saddleback Gunnel - - - 2 2 79 83 3.0 Y Snake Prickleback ------0 Arrow Goby - _ ------W Finscale Goby - - 0.3 11 14 - 25 0.8 Y English Sole Juvenile 6 1 2 2 2 5 18 0.6 Y 4 Bay Pipefish 0.3 0.3 - 0.5 - 1 2 0.07 Y 5 Black Rockfish ------13 0.4 Su Threespine Stickleback 4 - 2 1 - - 7 0.2 Y Tom Cod 0.3 - - - - - 0.3 - 0 Silver Salmon ------0 King Salmon ------0 Longfin Smelt ------Y Speckled Sanddab ------0 Sand Sole 0.3 ------U Starry Flounder 0.3 - - - 1 1 0.03 Y Table 10. (continued)

Date of Seining 4-8 %2 Species Caught 2-4 2-25 3-10 4-22 6-13 Total1 S.0.0 3 American Shad ------Brown Smoothhound ------Su

Total4 608 950 524 334 91 575 3081

1Total number of fish for a given species. 4 2The percent that a given species comprised of the total number of individuals for all seine hauls. 6 3Seasonal Occurrence: Y, found over the entire sampling period; W, winter; Sp, spring; Su, summer; 0, occasional. 4Total number of fish collected in each seine haul. Table 11. Number of fish collected in gill nets fished over a six hour tidal cycle in the Arcata Small Boat Basin (January-August, 1972).

Date of Gill Netting 1 Species Caught 1-8 4-8 4-22 5-7 5-28 6-13 6-24 7-6 7-27 8-19 Total3 4 % Staghorn Sculpin - 1 3 14 91 73 34 8 6 41 271 25.0 Juvenile Surf Smelt - - 23 - - - - 1 - - 24 2.3 Adult Herring 62 1 - 2 - 2 - - - - 67 6.1 4

Shiner Perch Male - - - - - 2 4 9 - - 15 1.4 7 Shiner Perch Female - 4 1 17 6 10 21 9 - - 68 6.2 Shiner Perch Juvenile ------2 1 - 25 28 2.6 Walleye Surfperch ------1 10 6 9 26 2.4 White Surfperch ------1 2 1 - 4 0.4 Topsmelt - 19 4 11 9 8 1 - 11 1 64 6.0 Jacksmelt - 42 6 4 10 - - - - - 62 6.0 N. Anchovy Larvae ------N. Anchovy Juvenile - - 50 230 7 7 - - 1 4 299 27.2 Table 11. (continued)

Date of Gill Netting 1 Species %4 Caught 1-8 4-8 4-22 5-7 5-28 6-13 6-24 7-6 7-27 8-19 Total3

N. Anchovy Adult - - 2 - - - 128 15 1 - 146 13.3

Saddleback Gunnel ------1 - - 1 0.09

Snake Prickleback ------

Arrow Goby ------

Finscale Goby ------4 English Sole 8 Juvenile - - 1 - - - - 1 - - 2 0.2

Bay Pipefish ------1 - - 1 0.09

Black Rockfish - - - - - 2 - - - - 2 0.2

Stickleback - - - - 1 - Threespine - - - - 1 0.09

Tom Cod ------

Silver Salmon ------

King Salmon ------

Longfin Smelt ------

Speckled Sanddab ------Table 11. (continued)

Date of Gill Netting Species1 Caught 1-8 4-8 4-22 5-7 5-28 6-13 6-24 7-6 7-27 8-19 Tota13 %4

Sand Sole ------Starry Flounder 2 1 ------3 0.3 American Shad ------Brown Smoothhound - - 1 - - 3 7 3 - - 14 1.3 2 Total 68 91 278 124 107 199 61 26 80 1098 4 9 1See Appendix IV for list of scientific names. 2Total number of fish collected in each gill net setting. 3Total number of fish collected for a given species. 4The percent which a l species comprised of the total number of viduals for all gilgill net settings. 50

Twenty-seven species of fish were collected over a nine month period (February-September, 1972). Six species (surf smelt, Pacific herring, shiner perch, northern anchovy, staghorn sculpin, and topsmelt), constituted the greatest numbers and biomass of fish. These species tended to be transient, coming into the area for 3-4 months before leaving. Although the number of topsmelt was not large, those caught were mature adults and thus contributed greatly to the total biomass. These species constituted 43%, 23%, 20%, 5%, 5.2%, and 0.8% respectively of the total number of fish taken in seine hauls at low tide from February-September 1972. Juvenile surf smelt reached a peak of about 10,000 individuals per seine haul in late February, 1972 (Figure 13). At this time they were the dominant species of fish constituting the greatest biomass. By late May, their numbers had decreased to about one-half making up 40% of the biomass by weight. it this time, they were co-dominant in numbers with the Pacific herring which reached a peak catch of about 8,000 juveniles in one seine haul (Figure 14). During this period herring constituted 16% of the total biomass of the seine haul be weight. By June, these two species of fish had moved out of the area and were replaced by shiner perch as the dominant species of fish. Shiner perch reached a peak of about 600 males, 600 females, and about 5,000 juveniles in late July 1972 (Figure 15). The shiner perch remained the dominant species of fish up to the termination of sampling. Two species of fish which may be of importance in contributing to the biota of the boat basin are the northern anchovy and the staghorn sculpin. The northern anchovy reached a peak of about 1,700 juveniles in late May, 1972 (Figure 16). The staghorn sculpin reached a peak of 51 (February-September, 1972). (February-September, 1972). Figure 13. Number of surf smelt taken at low tide by beach seine in the Arcata Small Boat Basin smelt taken at low tide by beach seine in the Arcata Figure 13. Number of surf 52 (February-September, 1972). (February-September, 1972). Figure 14. Number of Pacific herring taken at low tide by beach seine in the Arcata Smal1 Boat Basin herring taken at low tide by beach seine in the Figure 14. Number of Pacific 53 (February-September, 1972). (February-September, 1972). Number of shiner perch taken at low tide by beach seine in the Arcata Small Boat Basin at low tide by beach seine in the Arcata Small Number of shiner perch taken • Figure 15 54 (February-September, 1972). (February-September, 1972). Figure 16. Number of northern anchovy taken at low tide by beach seine in the Arcata Small Boat Basin anchovy taken at low tide by beach seine in the Figure 16. Number of northern 55 about 1,200 juveniles on the same date (Figure 17). Of minor importance were the larvae of the jacksmelt (Figure 18) and topsmelt (Figure 19), reaching a peak of 32 and 211 individuals respectively in plankton tows taken in early June, 1972. Species of Potential Sportfishing Interest. Six species of mature fish potentially of sport fishing interest were collected over the entire sampling period: adults of the Pacific herring, jacksmelt and topsmelt, northern anchovy, shiner perch, and brown smoothhound. Sixty- two ripe herring were taken by gill net in early February. There were 35 mature males and 26 ripe females. In early April mature topsmelt and jacksmelt appeared in the catch. They were collected by gill net. Of the 19 ripe jacksmelt there were 16 mature males and only 3 mature females. Of the 42 mature topsmelt there were only 5 ripe males and 37 ripe females. Eighty-seven mature northern anchovy showed up for the first time during late June. Gravid female shiner perch appeared in the catch in late April, reaching a peak in early July. Mature males which did not show up until late June, reached a peak at the same time as the female. Mature brown smoothhound were taken only in small numbers. Figure 17.Numberof staghornsculpintakenatlowtideby beachseineintheArcataSmallBoat Basin

(February-September, 1972). Number ofSc ulpin (in hundreds) 56 56 Figure 18.Numberof jacksmelttakenatlowtidebybeach seineintheArcataSmallBoatBasin

(February-September, 1972). Number of Jacksmelt (in hundreds)

7 7 5 Figure 19.Numberof topsmelttakenatlowtidebybeach seine intheArcataSmallBoatBasin

(February-September, 1972). Number of Topsmelt (in hundreds) 58 58 59

Seasonal Occurrence by Species. Fish were classified as to the time of year they were present in the catch as follows: species always present (Y); species found only during the winter (W); species found only during the spring (Sp); species found only during the summer (Su); and species of fish occurring only occasionally in the catch (0). Species classified as year-long (Y) include the juveniles of: the saddleback gunnel, finscale goby, English sole, bay pipefish, starry flounder, stickleback, staghorn sculpin, and surf smelt. With the exception of the staghorn sculpin and the surf smelt, these species appear consistently in the batch but in low numbers. Fish classified as winter and spring (W & Sp) and spring and summer (Sp & Su) include the Pacific herring, topsmelt, jacksmelt, shiner perch, and northern anchovy. There was a cyclical nature about many of these species. First the adults appeared heavily in the catch, with the larval and juvenile forms showing up in the catch some time later. Fish classified as summer only (Su) include the juveniles of the walleye surfperch, white surfperch, black rockfish, and brown smoothhound. Fish classified as occasional (0) include the tom cod, king and silver salmons, snake prickleback, arrow goby, speckled sanddab, sand sole, redtail surfperch, larval gobiids, and American shad. Kinds and Numbers of Invertebrates. The invertebrates of this area will be reported by three principal groups: benthic fauna, free swimming fauna, and plankton. A more detailed description of these groups may be found in Appendix III.

A list of the species of invertebrates and their numbers taken in beach seines at low tide are listed in Table 12, at high tide in Table 12. Number of invertebrates collected in beach seines fished at low tide in the Arcata Small Boat Basin (January-September, 1972).

Date of Seining Species Caught 1-81 2-4 2-25 3-10 4-8 4-22 5-7 5-28 6-24 7-6 7-27 8-19 9-16 Total3 %4

Cancer magister 2 - 2 - 1 - 1 - 8 0.02 Hemigrapsus oregonensis - 3 2 1 - 4 - - 2 - - 2 - 14 0.04 Crago franciscorum - 79 895 718 252 139 162 154 62 33 614 121 267 3496 11.0 6 Mysid - - 64 57 291 16813 9505 58 5 - 11 - - 26804 82.0 0

Protomedia sp. - 3 5 3 2 333 - 4 2 - 21 2 6 381 1.2 Amphithoidae 16 0.05

Corophium sp. - - - - - 78 14 9 - - - - 101 0.3 Livoneca californica - - - - 2 1 10 35 20 16 137 7 24 252 0.8

Paracerceis sp. - 2 0.1 ------2 0.006 Gemma gemma - - - 23 2 - 2 4 - 1 21 - - 53 0.2 Lyonsia californica - 22 2 14 ------19 23 80 0.2 Macoma baltica - - - - 6 - - - 2 1 - 1 7 17 0.002 Table 12. (continued)

Date of Seining Species Caug 1-81 2-4 2-25 3-10 4-8 4-22 5-7 5-28 6-24 7-6 7-27 8-19 9-16 Total &4

Aglaja sp. - 7 200 552 371 124 - 125 - - 35 1 - 1415 4.3

Polynoidae - 1 - - 2 39 2 14 4 - 40 5 15 122 0.4

Goniada sp. - 1 - - 1 2 0.006

Orbiniid sp. - - - 1 - 1 2 0.006

Spionidae ------6 1 Nereis sp. - - - 1 1 0.003 2 Phyllodocidae - 1 - - 1 - 4 0.01

Unidentified polycheates ------_ - - - _ - -

Nemertian 2 2 - 6 0.02 2 Total 2 119 1170 1372 933 1753 9700 403 99 51 895 158 342 32776

1 Takenht in gill net. 2 Total number of invertebrates in each seine haul. 3 Total sp.er of invertebrates of a given species collected at low tide.

4The percent that a given species comprised of the total number of invertebrates collected in seines at low tide. 62

Table 13, and by Eckman Dredge in Table 14. I separated benthic fauna into two assemblages; infauna, and epifauna. Infauna may be considered those organisms which live within the substrate. Epifauna may be considered as those organisms which live on or about the substrate. Infauna was composed predominantly of spionid polycheates (Table 14), which qualitatively over the entire sampling period appeared to form the greatest stable biomass. Spionid polycheates are both deposit feeders and filter feeders, consuming bottom deposits as well as sus- pended detritus (Barnes 1968). Other infauna were the bivalves: Lyonsia californica Conrad, 1837, Gemma gemma (Totten, 1834), and Macoma baltica (Broderip and Sowerby, 1829), and the gammarid amphipods, Corophium. Epifauna consists primarily of the shrimp, Crago franciscorum (Stimpson, 1859), the tectibranch, Aglaja; gammarid amphipods: Amphitho- idae, and Protomedia; polycheate, Goniada, Phyllodocidae, Eunereis, Orbiniid; crabs: Hemigrapsus oregonensis (Dana, 1851), Cancer magister Dana, 1852; and the isopod, Paracerceis. Mysids and the isopod, Livoneca californica Schioedte and Meinert, 1883-1884, a parasite of fish, were found higher in the water column (free swimming). Mysids (Figure 19) occurred in swarms reaching a peak catch of about 17,000 individuals on April 22, 1972. They appeared ripe with eggs and some contained sacs of unliberated zoea. Livoneca californica was recorded free in the catch and clinging to fish, especially shiner perch. It is my opinion that the free isopods were individuals which released themselves from their host upon capture. Predominant planktonic forms were the copepods Acartia clausii Giesbrecht, 1889, Acartia tonsa Dana, 1848, Eurytemora, and to a lesser 63

Table 13. Number of invertebrates collected in beach seines fished at

high tide in the Arcata Small Boat Basin (February-June, 1972).

Date of Seining Species 2 Caught 2-4 2-25 3-10 4-8 4-22 6-13 Total1 % Cancer magister ------

Hemigrapsus oregonensis 1 - - - - 1 2 0.4

Crago franciscorum 79 35 60 43 24 38 279 62.0

Mysid 6 4 6 34 24 26 100 22.1

Protomedia sp. 3 - 0.3 - - 17 20 4.4 Amphithoidae - - 1 - - - 1 0.2

Corophium sp. - - - - - _ _ -

Livoneca californica ------

Paracerceis sp. 1 - 0.3 - - - 1 0.2

Gemma gemma ------

Lyonsia californica 22 - - - - - 22 5.0 Macoma baltica - - - - - 1 1 0.2

Aglaja sp. 7 5 4 5 - 1 22 5.0 Polynoidae 0.3 ------Goniada sp. 0.3 - 0.3 - - - 1 0.2

Orbiniid sp. ------

Spionidae ------

Nereis sp. - - - - - 1 1 0.2

Phyllodocidae 0.3 ------

Unidentified polycheates ------64

Table 13. (continued)

Date of Seining Species Caught 2-4 2-25 3-10 4-8 4-22 6-13 Total1 %2

Nemertian ------Sea Anemonae ------1 0.2 Dragon Fly Pupae 0.3 ------Dragon Fly Nymph 0.3 ------Damsel Fly Nymph 1 - 0.3 - - - 1 0.2 Fresh Water Gastropod - - 0.3 - - - - - Total3 122 44 73 82 48 86 452

1 The total number of invertebrates of a given species collected at high tide. 2The percent that a given species comprised Nymphthe total number of individuals collected in seines at low tide. 3The total number of invertebrates collected per each seine haul. 65

Table 14. Number of invertebrates collected by Eckman Dredge in the

Arcata Small Boat Basin (April-August, 1972).

Date of Dredging Species Caught 4-22 6-13 6-24 7-6 7-27 8-19

Cancer magister ------

Hemigrapsus oregonensis ------

Crago franciscorum - - - - - 1 *1 Mysid - - - - - Protomedia sp. - 1 - 6 - _

Amphithoidae ------2 Corophium sp. #2 - - - - -

Livoneca californica ------

Paracerceis sp. ------

Gemma gemma - - 4 7 1 4 Lyonsia californica - - 6 8 3 9

Macoma baltica 3 2 - 2 - - Aglaja sp. - - - 2 - -

Polynoidae - - - - - 2

Goniada sp. ------

Orbiniid Ea - - - -

Spionidae #12

Nereis sp. - - - 1 - 3 * 1 Phyllodocidae - - - - -

Unidentified 1 Polycheates - - - - - * 1Species present but numbers not recorded. 2Rank of abundance of species, though numbers not recorded 66 (February-September, 1972). (February-September, 1972). Figure 20. Number of mysids taken at low tide by beach seine in the Arcata Small Boat Basin taken at low tide by beach seine in the Arcata Small Figure 20. Number of mysids 67

extent, harpacticoid copepods. These groups as individual species or in combinations, made up the greatest portion of the planktonic biomass by numbers and weight. Of lesser importance were larvae and nauplii of a few organisms. SOURCES OF ERROR

Southport Channel Poor water clarity in Humboldt Bay is a limiting factor en- countered by scientist using SCUBA techniques. In February and March, when artificial reef structures were placed in Southport Channel, visibility was near zero. The only light I could discern was from bioluminescent dinoflagellates. Because of my inability to make underwater observations on the structures until May, I was unable to specify exactly when the attachment of organisms occurred over this interval of time. It may then be questioned whether the contrasting difference in growth of attaching organisms between the ID and PL structures (Table 6) could have been due to the time lag difference in the placement of the structures (mid-January versus early March). Lambert (1972) found that January-March was a period of slight or no growth in his studies on the attachment of organisms to the PL structures on the main reef. The fact that the experimental PL and the main reef PL structures all showed basically the same succession and growth of fauna contrasting with the AD and high profile structures, indicates that differences in abundance of attaching organisms was due to struc- tural design and not to time of placement of the units. Poor visibility also can produce bias in estimation of kinds and numbers of fish present. Estimating the number of fish within the structures was not a problem. However, I noted that more schools of open-water fish were recorded under conditions of better visibility. Under-estimation could be related to several factors: decreased visibility to the diver and/or behavioral reaction of fishes. Decreasing 69 visibility may cut down the divers sight, decreasing his area of vision and therefore the number of fish he will encounter. Prince

(1972), however, noted that with decreasing visibility and strong currents at tidal changes, the fish tended to take refuge in the tires and thus would be counted as resident fish inside of the structures.

I personally believe it is a combination of both of these factors, for even at slack tide with a few feet of visibility, fewer fish were seen as compared to a clear day (four to eight feet of visibility) at slack tide. On a poor or clear day, as the tides begin to change, the populations of fish decrease in numbers, apparently to take refuge in the tires or to move elsewhere. Therefore, in comparing estimates of reef populations on given days or times of the year, physical factors may be the major controlling force in the fish populations, and should be taken into account when making population estimations.

Fields Landing Wreck A large part of the sampling of fish on Fields Landing Wreck was conducted by rod and reel. Biased results were evident from differences in the competence of the fishermen and bait employed. Very often students of poor fishing ability volunteered their services. This resulted in a lower catch per unit of effort than might be expected by a stand- ardized method of hook and line fishing (,Allen et al. 1960 and Men et al. 1970).

Bait also seemed to bias the catch: shrimp caught mostly surfperch, and anchovy caught predominantly jacksmelt.

Conditions on the Bay were also an important influence on the rate of catch. On a few days large waves developed during the sampling 70

period. In these shallow waters, I would expect the behavior of any fish to be drastically affected. This was very dramatically shown by a low catch on April 16, 1972. Estimation of fish populations by diving were subject to the same factors as discussed for Southport Channel studies.

!Arcata Small Boat Basin It may be questioned how representative the beach seine hauls were of the fish population. Since the area swept by the net covered at least 40% of the basin area, I believe the data collected were fairly characteristic of the fish population in the Arcata Small Boat Basin. Another question which might arise is why "Debris" was calculated in part A of Table 3. Although the seine haul was thoroughly washed, it was impossible to get rid of all of the debris. This residue debris became part of the total weight of the seine haul, and was present in the subsamples. Its presence affected the calculation of the total weight of the subsamples (Table 3), and the per cent that species constituted in the seine haul. Finally, in the calculations of the subsamples, all fish were treated equally regardless of size or weight. The only extremely large fish ever taken in sampling were collected by gill net. Thus I believe that figures given for combined subsamples are unbiased in this respect. IMPLICATIONS FOR FISHERIES MANAGEMENT

This portion of the paper will examine the potential fisheries management problems in using artificial reefs in intertidal areas. Detailed information of the biology of species taken in the study areas are presented in Appendixes I, II, and III.

Southport Channel (Subtidal Artificial Reefs) Fish and Invertebrates. From the number of fish alone, it is obvious that the AD low profile structure showed a greater potential for fish attraction. From my observations, it appeared that the copper rockfish, which resided within the PL structure, were transient. Their numbers varied with each dive. In contrast, the number of copper rockfish were constant on the ID structure suggesting permanent residency. This is also suggested by the behavioral pattern of the copper rockfish. They swam off the AD structure seemingly to investigate the intruding diver. The abundant growth on the AD reef acted as a food source for kelp greenling and provided living space for other potential food organisms. ,The increased food per-unit area would enable the AD reef to sustain a greater population of resident fish. I believe the one predominant reason for the greater attraction of fish to the AD structure was the increased number of living spaces (the tire openings provided for the fish). The AD structure with its many openings tended to slow down the strong tidal currents which provided a place where fish could take refuge, and in time, establish residency. The reduced current velocity also resulted in increased growth of attaching organisms on the AD structure. The PL reef failed to attract resident populations of fish and 72

attaching organisms, because the design (tires placed side by side forming a tubular structure) allowed currents to sweep unobstructed over and through the structure which made it very difficult for the fish to establish permanent residency. The strong currents, which scoured the PL reef, hindered the attachment of most organisms.

Barnacles, because of their adhesive cement, were the only attaching organisms which became well established on the PL structure.

In alternate explanation which may be working in conjunction with the strong currents to influence the growth of attaching organisms has to do with the idea of vertical surface areas (Reiner 1942). The

PL structure because of its large horizontal surface area allows for the collection of sediment. Attached organisms are easily buried by heavy silt deposition. On the other hand the AD structure, was constructed with a large vertical surface area, making deposition of silt less likely and the settlement of attaching organisms more likely. The settling of barnacles on the PL structure may be explained by their greater ability to tolerate sedimentation. Balanus crenatus larvae are also known to be photopositive and tend to seek exposed horizontal surface areas (Thorson 1964).

I feel that the placement of these structures was also important to their failure or success. The narrowest portions of both structures faced parallel to the channel and were directly in line with the tidal currents. The only openings of the PL reef are directly in line with the currents. If this structure had been turned perpendicular to the channel, the openings would have been excluded from the main force of the tidal currents. Probably, a more fitting shelter would have then been provided for the establishment of resident fish populations. Con- 73 versely, the AD structure was favorably positioned parallel to the channel. In this position, the current must penetrate five thicknesses of tire openings as compared to two thicknesses in a perpendicular position. Current velocities were reduced and provided favorable conditions for local fauna. Siltation. Siltation is heavy in Southport Channel. Many of the low profile reef structures placed by Gotshall in 1968 have been completely silted-in. As a result of siltation of low profile units the environment has changed from a low profile reef environment inhabited predominantly by copper rockfish, to a high profile reef environment inhabited predominantly by the more transient black rockfish (Prince and Lambert 1972). Even the high profile structures of the main reef have tires seven to eight feet above the substrate filled to the rims with sediment which is carried by the strong currents in the channel. Siltation on both the AD and PL reefs became evident within about five months after placement in the channel. I believe that over a period of time the AD structure can withstand siltation better because the tires are held off the substrate by the cement base. Thus it appears that the Ad structure is superior in all cate- gories: (1) in fish and invertebrate attraction, (2) in growth of attaching organsims, and (3) in reduced siltation. A disadvantage is the cement base which makes the structure slightly awkward to handle prior to placement under water. The AD structure has not been tested in intertidal waters. An artificial reef using the AD design needs to be studied in intertidal waters in Humboldt Bay. 74

Fields Landing Wreck (A Simulated Intertidal Artificial Reef)

Pros and Cons of Intertidal Reefs. Because the intertidal reef is inhabited predominantly by transient species of fish, (surfperch, and smelt), it might be more difficult to over-fish an intertidal reef population as opposed to a more resident subtidal reef population which may be depleted due to heavy fishing pressures (Prince 1972). Another advantage of the intertidal reef is its accessibility to the general public. Possession of a boat is required to fish the deeper channels of the Bay and ocean. A reef in intertidal waters adjacent to a pier may provide recreation for countless numbers of sportsmen and their families. Gotshall (1966) felt piers could potentially provide the most effective and inexpensive means to meet future sport fishing requirements in Humboldt Bay. Prince and Lambert (1972) reported placement of an artificial reef under a pier at Santa Cruz increased fishing success.

A disadvantage of intertidal reef fishing in Humboldt Bay is the reliance upon the tides. The best fishing occurred from one hour before high slack tide until about an hour after high slack tide. Fishing improves as fish are carried past the reef by the incoming tide, and as the fish leave with the out-going tide. This is even true on the subtidal reef of Southport Channel where the strong currents reduce the catch per unit effort. This results from the behavioral phenomena exhibited by the fish which move out of range of the fishermen's bait.

Future Utilization of Artificial Reefs in Humboldt Bay

It appears from the dives made on Fields Landing Wreck and on the main reef of Southport Channel, and from the rod and reel survey of the wreck, that many species of fish leave the shallows of the bay in the 75

late spring and summer months. They apparently move into deeper channels or elsewhere. Only juveniles utilize the shhllow section of the wreck during the summer months. The occurrence of white surfperch, striped surfperch, and pile perch on the main reef in Southport Channel seems to verify this hypothesis. This may partially explain the low summer catches of striped surfperch off the South Jetty (Smith 1967), and the disappearance of the schools of surfperch around Fields Land- ing. Pile perch which previously avoided the deep open mid-water channels of the Bay (Smith 1967) have been observed in schools on the subtidal reef in Southport Channel, probably as a result of a thigmotropic effect (the attraction of fish to a solid object). It is difficult to realize all of the ramifications of these artificial reefs and exactly how they alter the environment.

DeWees (1970) and Prince (1972) reported difficulty in catching fish by rod and reel in late fall through early spring. It seems that by fishing both the intertidal and subtidal reefs during the right times of the year the utilization of the available resources could be greatly increased. The subtidal reef should be fished in the late spring, summer and early fall when the catch per unit of effort appears greatest. Inter- tidal reefs in Humboldt Bay should be fished in late fall, winter, and early spring.

Arcata Small Boat Basin (Potential Intertidal Reef Site)

I believe the variation in numbers of fish and invertebrates taken at high and low tides is due to the shallowness of the Bay. The large tidal prism, exposes the mud flats, and concentrates the fish and epifaunal invertebrates in the intertidal channels. 76

Species of Fish. The intertidal channels and mud flats appear to be spawning and nursery grounds of the Pacific herring, topsmelt,

shiner perch, and very likely the jacksmelt, bay pipefish, surf smelt,

northern anchovy, brown smoothhound, and three spine stickleback. This

area appears to be a nursery ground of the English sole, starry flounder,

staghorn sculpin, black rockfish, walleye surfperch, white surfperch,

and saddleback gunnel. These species are all estuarine dependent, that is, in some period of their lives they inhabit the intracoastal waters and bays, lagoons and marshes (Skud and Wilson 1960). Of all of the above mentioned species only the English sole can be considered quasi- catadromous; that is the adults spawn off-shore, while the young move inshore to less saline waters (Skud and Wilson 1960). Invertebrate Fauna. Invertebrate fauna in the basin offer an abundant source of food for the many species of fish. It seems that if artificial reefs were placed in or around the basin that along with the already existing invertebrate fauna and organisms which would attach to the reef, there would be an abundance of food for any sport fish attracted to the area. 76

Species of Fish. The intertidal channels and mud flats appear to be spawning and nursery grounds of the Pacific herring, topsmelt, shiner perch, and very likely the jacksmelt, bay pipefish, surf smelt, northern anchovy, brown smoothhound, and three spine stickleback. This area appears to be a nursery ground of the English sole, starry flounder, staghorn sculpin, black rockfish, walleye surfperch, white surfperch, and saddleback gunnel. These species are all estuarine dependent, that is, in some period of their lives they inhabit the intracoastal waters and bays, lagoons and marshes (Skud and Wilson 1960). Of all of the above mentioned species only the English sole can be considered quasi- catadromous; that is the adults spawn off-shore, while the young move inshore to less saline waters (Skud and Wilson 1960). Invertebrate Fauna. Invertebrate fauna in the basin offer an abundant source of food for the many species of fish. It seems that if artificial reefs were placed in or around the basin that along with the already existing invertebrate fauna and organisms which would attach to the reef, there would be an abundance of food for any sport fish attracted to the area. RECOMMENDATIONS

1. Local sport fishermen should be informed as to the time of year and time of day that fishing success is most likely.

2. The Arcata Small Boat Basin is recommended as an excellent site for future ecological studies because of its access and available back- ground data.

3. Before reefs can be placed within the !Arcata Small Boat Basin, its potential as a sport fishing location should be discerned. Further dredging will be required to straighten out the sloughed in channels and basin edges. Bank stabilization structures should be designed which might also act as potential artificial reefs, such as jetties of rubble and clam shell.

4. As in the original study plan, the AD structure or some other units should be placed in or around sites within the Arcata Boat Basin, and a study made concerning the attraction of fish and invertebrates.

5. Additional study of artificial reefs in intertidal waters should take place in areas of minimal siltation, near piers and other access sites.

6. Further development of estuaries within Humboldt Bay should be kept minimal until more elaborate studies can be performed concerning the effects of destruction of the estuaries on the biological system as a whole. LITERATURE CITED

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Edmund, Norman W. 1967. Old tires: the ideal material for building fish havens. Edmund Sci. Co., Barrington, N.J. 16 p. Eldridge, M.B. 1970. Larval fish survey of Humboldt Bay. M.S. Thesis. Humboldt State College, Arcata, California. 52 p.

Frey, Herbert W., Ronald F. Hern, and Jack L. Spruill. 1970. Report on the natural resources of Upper Newport Bay and recommendations concerning the Bay's development. Calif. Dept. Fish and Game. 68 p.

Glassey, Dan. 1972. Identification and general food habits of the invertebrates of the Arcata Small Boat Basin. Unpublished manuscript for Intertidal Ecology, Dr. DeMartini. California State Univ., Humboldt, Arcata, California. 26 p.

Gore, Kenneth L. 1971. Seasonal and spatial distribution of copepods in North Humboldt Bay. M.S. Thesis. Humboldt State College, :Arcata, California. 58 p.

Gotshall, D. W. 1966. Marine resources of Humboldt Bay. p 23-26. In A Symposium on Humboldt Bay. Center for Community Development, Humboldt State College, Arcata, California.

Gunter, Gordon, 1945. Studies on marine fishes of Texas. Pub. of the Univ. of Texas Inst. of Marine Science 1(1): 190 p.

. 1950 Seasonal population changes and distribution as re lated to salinity of certain invertebrates of the Texas Coast, in- cluding the commercial shrimp. Univ. of Texas, Inst. of Mar. Sci., Pub. 1(2): 7-51.

Haertel, Lois and Charles Osterberg. 1967. Ecology of zooplankton, benthos, and fishes in the Columbia River estuary. Ecol., 48(3): 459-472. Hart, John Lawson and J. Laurence McHugh. 1944. The smelt (Osmeridae) of British Columbia. Fish. Res. Bd. Can., Bull. No. 64: 1-27.

Hedgepeth, Joel W. 1951. Obtaining ecological data in the sea. p 43-- 56. In Joel W. Hedgepeth (ed.), Treat. on mar. ecol. and paleoecol. Mem. Geo. Sci. Amer. 67(1): 53-86.

Herald, Earl S. and Donald A. Simpson. 1955. Fluctuations in abundance of certain fishes in South San Francisco Bay as indicated by sampling at a trash screen, Calif. Dept. Fish and Game. 41(4): 271-278. Hourston, Alan S. 1958. Population studies on juvenile herring in Barkley Sound, British Columbia. Fish. Res. Bd. Can. 15(5): 909- -949. Hulburt, E.M. 1957. The distribution of Neomysis americana in the estuary of the Delaware River. Limnol. and Oceanogr. 2(1): 1-11. 80

Icanberry, John William. 1971. Seasonal distribution of meroplankton in North Humboldt Bay. M.S. Thesis. Humboldt State College, Arcata, California. 48 p. Israel, H.B. 1936. A contribution towards the life history of two California shrimps, Crago franciscorum (Stimpson) and C. nigrieauda (Stimpson). Calif. Dept. Fish and Game, Fish Bull. No. 46: 1-26. Keller, Mathew. 1963. The growth and distribution of eel grass (Zostera marina L.) in Humboldt Bay, California. M.S. Thesis, Humboldt State College, Arcata, California 55 p. Lambert, Thomas R. 1972. Season of attachment, substrate preference abundance of colonizing organisms on an artificial reef in Hum- boldt Bay, California. M.S. Thesis, Humboldt State College, Arcata, California. . 1972. Food habits of fish along an eight fathom contour in a subtidal sand environment off Samoa, California. Unpublished manuscript for Benthic Ecology, Dr. De Martini, California State Univ., Humboldt, Arcata, California. 10 p. Light, W.R., R. Smith, D.P. Pitelka, Abbot and Frances M. Weisner. 1964. Intertidal invertebrates of the central California coast. Univ. Calif. Press, Berkeley, California. (4th ed.). 446 p. McBee, James T. 1971. Seasonal and spatial distribution of zooplankton in South Humboldt Bay. M.S. Thesis. Humboldt State College, Arcata, California. 81 p. Messersmith, James. 1966. Fishes collected in Carquinez Strait in 1961- 1962. p 57-63. In D.W. Kelly, Ecological studies of the Sacra- mento-San Joaquin estuary. Calif. Dept. Fish and Game, Fish Bull. No. 132: 133 p. Miller, Daniel J., Dan Gotshall, and Richard Nitsos. 1965. A field guide to some common ocean sport fishes of California. State of California, The Resources Agency, Calif. Dept. Fish and Game. 87 p. Misitano, David A. 1970. The early life history of English sole in Humboldt Bay. M.S. Thesis, Humboldt State College, Arcata, Calif- ornia. 50 p. Montgomery, Kinsley, V. 1971. Proposed Arcata public fishing pier - An evaluation of fishery potential. Unpublished manuscript for Fisheries 195, Dr. George H. Allen., Humboldt State College, Arcata, California. 14 p. Newell, G.E., and R.C. Newell. 1963. Marine plankton, a practical guide. Anchor Press, Tiptree, Essex, Great Britain. 221 p. 81

Orcutt, Harold George. 1950. The life history of the starry flounder Platichthys stellatus (Pallas). Calif. Dept. Fish and Game, Fish. Bull. No. 78: 1-64.

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Pierce, Allen A. Jr. 1965. A report on a 24-hour beach seining study conducted in Humboldt Bay, California. Unpublished manuscript for Fish- eries 195, Dr. George H. Allen, Humboldt State College, Arcata, California. 20 p.

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Washington, University of. 1955. Humboldt Bay, California - a literature survey. Univ. of Wash., Dept. of Oceanogr. 144 p. Work performed under Contract No. N 62305-303, U.S. Navy Hydrographic Office.

Webb, R.D. and R.E. Noble. 1966. A device for randomly sampling juvenile fish populations. Wash. Dept. Fish., Fish. Res. Papers. 2(4): 94-103.

Weeks, Ann. 1972. Fish cities, a new school design. N.O.A.A. 2(2): 25-29. Westrheim, S.J. 1955. Size, composition, growth and seasonal abundance of juvenile English sole (Parophrys vetulus) in Yaquina Bay. Oregon Fish Comm. Res. Briefs, 6(2): 4-9. APPENDIX I

UNDERWATER OBSERVATIONS BY SCUBA IN SOUTHPORT CHANNEL ON ARTIFICIAL REEFS IN SUBTIDAL LOCATION

Underwater observations at high slack tide by SCUBA on experimental reefs and the main reef located in Southport Channel were conducted from early May-September 1972. Details of observations are listed by date of each individual dive.

May 5, 1972

Initially, no fish were observed to swim within the PL structure.

Eight to ten copper rockfish and as many yearling black rockfish swam in and around the AD structure. Some time later five yearling black rockfish were observed on the PL reef apparently using it as a place of temporary retreat. Three kelp greenling were observed in the lower section of the AD reef. A number of the copper rockfish swam out forming a line parallel to the AD reef. They ventured from six inches to one foot off the structure seemingly to investigate me. The PL structure was virtually devoid of attaching organisms, with only a minimal growth of the hydrozoan, Obelia borealis, a few encrusting tunicates, Didemnum cranulentum; and one nudibranch. In contrast, the growth of 0. borealis was so great on the AD structure that the unit appeared as a massive underwater shrub. The same contrast was observed on the main reef (high profile structures compared to the typical low profile structures). The contrast was so great that the PL structure was barren in comparison to the AD and high profile structures. Silta- tion on the two structures was minimal at this time. 84

May 26, 1972

Much of this dive was spent in relocation of the structures and in securing a buoy which had been torn off on the previous dive. Location of the structures was extremely difficult due to the poor visibility.

Once again, I observed more fish on the AD reef compared to the PL reef. Because of my limited air supply actual counts were not taken.

It this time the hydrozoan bloom was so thick that the fish were forced to utilize the upper portion. The first live rock crab was seen on the

ID reef; previously only exoskeletons had been observed.

June 1, 1972

Five copper rockfish and five yearling black rockfish were observed within the AD structure. Yearling black rockfish hovered over both structures. Growth of attaching organisms had increased slightly on the PL structure primarily due to the settling of the barnacle, Balanus crenatus. Barnacles had also settled on the AD structure. They did not cover as great an area as on the PL reef due to exclusion by the already dominant hydrozoan growth. Some siltation had occurred. Tires of both the PL and AD structures had filled in up to the lower rims. There was some siltation on the cement base of the AD structure. The tires of the PL structure had settled slightly into the muddy bottom.

June 22, 1972

There were eight copper rockfish within the AD structure, and two cooper rockfish and two black rockfish within the PL structure. Three pairs of rock crab, Cancer productus, were observed breeding on the AD structure and three individuals moved about freely. 85

July 28, 1972

The clearest waters yet experienced in Humboldt Bay were present on this dive. Visibility ranged from six to eight feet, as compared to about two to three feet on an average day. Schools of white surfperch and yearling black rockfish were observed hovering over the structures. A three pound black rockfish and a few scattered pile perch were also seen. Six to eight copper rockfish were seen within

the AD structure.

The copper rockfish moved to the edge of the structure to observe

me. They never ventured more than a foot or two from the reef always

having an opening for a retreat. The PL structure was inhabited mainly by yearling black rockfish. Barnacles had become the dominant at-

taching organisms on the AD reef while the hydrozoans decreased in

abundance (see text Figure 11).

The amount of silt in the tires remained at the same level as on previous surveys.

On the main reef a school of young-of-the-year black rockfish were observed for the first time.

August 3, 1972

Typical visibility of a few feet was experienced on this parti-

cular dive. A second settling of barnacles covered many of the en-

crusting tunicates and were replacing the dwindling number of hydro-

zoans. .Although the hydrozoans covering the exterior of the AD struc-

ture had decreased, they were still growing successfully within the

structure. There was no change evident in the amount of siltation on

either structure. 86

August 12, 1972 It appears that the physical and biological changes which affect the AD and PL units reached an equilibrium since there were no ob- servable changes in such parameters as siltation, growth and abundance of attaching organisms, and numbers of fish within units. Schools of 20-30 juvenile black rockfish were observed on the main reef. A large number of pile perch, singly and in groups of twos and threes were feeding on the attaching organisms. Schools of white surfperch, schools of yearling black rockfish, and schools of large black rockfish swam actively about the main reef.

September 3, 1972 Basically the same observations as above were made on the dive of September 3, 1972. Adult and young-of-the-year striped surfperch were observed for the first time. A gravid pile perch was speared. A dom- inance of barnacles and a disappearance of hydrozoans was noted on the main reef. APPENDIX II

UNDERWATER OBSERVATIONS BY SCUBA ON A WRECK ACTING AS AN ARTIFICIAL REEF IN INTERTIDAL WATERS AT FIELDS LANDING

Underwater observations by SCUBA on Fields Landing Wreck were conducted from June - September 1972. Details of observations are listed by date of each individual dive.

June 22, 1972

I made my first dive on the wreck accompanied by Mr. Eric Prince.

The area around the exposed section of the wreck was devoid of the surfperch and smelt that had been caught previously by rod and reel.

Juvenile black rockfish and two spotfin surfperch swam around this area of the wreck. The exposed section of the wreck was covered with algae.

Eel grass was drapped on the wreck. Four black rockfish ranging from four to six pounds swam about the subtidal portion of the wreck. The subtidal section of the wreck is covered with sabellid polycheates and sea anemonae. Two copper rockfish were speared by Mr. Prince who estimated their age at three-years-old.

June 29, 1972

As before, I failed to observe any schools of transient surfperch or smelt. The submerged section of the wreck contained ten to twenty black rockfish. Four of these rockfish were speared, one weighed four and one-half pounds, the other three were about one pound each.

August 12, 1972

Juvenile black rockfish and striped surfperch swam about and fed on algae attached to the exposed section of the wreck. One black 88 rockfish estimated at five pounds weight was noted in this shallow portion of the wreck for the first time. Ten to twenty black rockfish were around the subtidal portion of the wreck.

September 13, 1972 Two five-pound black rockfish and a five-pound ling cod were observed again in the exposed portion of the wreck, in two to three feet of water. Juvenile black rockfish and striped surfperch were also noted. No schools of surfperch or smelt were observed. It is my belief the adult rockfish and ling cod were entering these shallows to prey upon the juvenile fish. APPENDIX III

NOTES ON MARINE ECOLOGY OF THE ARCATA SMALL BOAT BASIN

Size and Growth by Species of Fish Starry Flounder. Starry flounder ranged from 112-330 mm in Jan- uary and February, 131-186 mm in June, 29-208 mm in July and 35-111 mm in August. Young-of-the-year ranged from 29-81 mm on May 28, 1972. On July 27, 1972 young-of-the-year ranged from 82-107 mm. This agrees with Radtke (1966) who found one to two-year-olds between October through April in the Sacramento-San Joaquin Delta, which corresponds to the 111-330 mm sized starry flounders taken in the seine hauls. Radtke found young-of-the-year from 30-100 mm, as a result of winter spawning, dominant from May through August, approximating the time this size class appeared in our catches. Sticklebacks and Bay Pipefish. Three-spine sticklebacks ranged from 17-47mm in February, 1972; 20-53 mm in July. Bay pipefish were taken sporadically in very low numbers, the adults ranging from 120- 223 mm. Beginning on June 6, 1972, the adults collected were primarily females with eggs. Larval and juveniles were taken on June 13, 1972 ranging from 21-72 mm. No males brooding eggs or young were captured. Surf Smelt. Juvenile surf smelt ranged from 26-56 mm in February and 40-71 mm in May. Eighteen adults ranging up to 116 mm were taken in February, and one ripe male 146 mm in length was collected in July. Staghorn Sculpins. Steady increase in growth of staghorn sculpins were recorded as follows: February 4, 21-37 mm; March 3, 21-69 mm; April 8, 85-142 mm and on August 19, 85-162 mm. 90

Pacific Herring. Pacific herring were first captured in gill nets in February. They were mature adults ranging from 215-272 mm. Approxi- mately two months later on April 8, larval and juvenile forms ranging from 16-46 mm in length appeared in considerable numbers. Topsmelt and Jacksmelt. Adult topsmelt ranging from 243-311 mm and adult jacksmelt ranging from 289-352 mm occurred together in schools in April and May. Their appearance in accordance with the findings of Roedel (1953) implies a regular spawning cycle. During this period, a large number of egg masses were collected in the seine. I believe they were topsmelt and jacksmelt eggs. Larval forms began to appear in June in extremely high numbers in plankton tows. This agrees with Carpelan (1955) who found that topsmelt breed from March through August. Clark (1929) found jacksmelt to breed from November through March. It appears that locally there is some variation in time of appearance of larval forms. Within two to three weeks larval forms were absent from the catch, and were apparently carried off by the tides. On July 27, 1972 one hundred and thirty-seven topsmelt ranging from 22-53 mm were collected in the catch. One individual measuring 68 mm was taken in a gill net on August 19. No juvenile jacksmelt were ever collected. The juvenile topsmelt had characteristics typical of the adults; length of jaw and intro-dorsal fin scale counts. Larval forms were differen- tiated by the following characteristics: Topsmelt had ventral pigmentation on their gut. There was dorsolateral pigmentation on the gut with no set pattern. Total myomere count was less than 50. Jack- smelt had no ventral pigmentation on the gut, but three to four distinct melanophores dorso-laterally on the gut, dorsal to these there was more pigmentation. Total myomere count was greater than or equal to 50. 91

Shiner Perch. Ripe shiner perch, ranging in size from 100-149 mm, showed up in low numbers in the catch for the first time in the month of April. By May 28, juvenile forms ranging from 47-70 mm, began showing up in seine hauls, and increased in numbers in subsequent catches along with the ripe females. By mid-August, the juveniles ranged from 52-95 mm. Male shiner perch ranging from 107-112 mm were not taken until June of 1972. In June and July, the females were so ripe that young often were aborted as we sorted the fish from the seine. By late July males ranged from 106-131 mm, spent females ranged from 106-144 mm and juveniles and larvae ranged from 52-87 mm. Miscellaneous Species. Summer occurring fish include the walleye surfperch, ranging from 64-75 mm, juvenile white surfperch ranging from 64-88 mm, juvenile black rockfish ranging from 52-61 mm and juvenile brown smoothhounds ranging from 254-264 mm. Larval northern anchovy ranged from 35-43 mm, juvenile and non-ripe adults ranged from 81-160 mm, and ripe adults ranged from 121-154 mm.

Possible Explanation of Occurrence of Fish and Invertebrates by Species General Considerations. The benthic fauna in the Arcata Small Boat Basin resembles that of the Columbia River Estuary, a few species constituting the bulk of the potential food for feeding fish (Haertel and Osterberg 1967). These species include a spionid polycheate, whose numbers apparently were greatest of all epifaunal and infaunal forms. At times, Crago franciscorum, Corophium, mysids, and Aglaia make up a large percentage of the existing biomass. Table 15 gives an indication of feeding types Massey 1972). Copepods, apparently, make up the predominant biomass throughout the 92

Table 15. Classification of invertebrates, by method of feeding, col-

lected in the Arcata Small Boat Basin.

Feeding Type Organisms

Detritus Neomysis sp. Feeder Crago franciscorum

Protomedia sp.

Amphithoidae

Corophium

Carnivore Aglaja diomedia

Goniada sp.

Phyllodocidae

Paranemertes peregrinia

Eunereis longpipes

Polyinoidae

Suspension Feeders Gemma gemma

Lyonsia californica

Macoma baltica

Deposit Feeders Spionidae

Orbiniid

Paracerceis sp.

Scavengers Hemigrapsus oregonensis

Cancer magister

Parasite Livoneca californica 93 water column and are a readily avilable food supply. :Although the numbers of copepods are low relative to other bays and estuaries (Gore 1971), it appears from the high incidence of larval, juvenile and adult fish recorded in this area of the bay, that copepod numbers and biomass along with benthic fauna are sufficient for providing an ade- quate food supply. What brings these many species of fish and invertebrates into this area to spawn and rear? Gunter (1945 and 1950) believes the cycle of spawning, growth, and movement, bears a distinct relation to salinity. In fact, salinity lower than that characteristic of the ocean is a prerequisite in early development for many of these species. Shuster (1959) expresses the belief that shallow bodies of water are extremely productive, most of their volume being exposed to high light intensities. The surrounding marsh lands in North Humboldt Bay, although dwindling (Thompson 1970) may be an important source of vitamin B12 (Starr 1956) and other vitamins and minerals necessary for the growth of some phytoplankton (Provasoli and Pinter 1953). Therefore, indirectly these marshes may be necessary for the survival of the juvenile and larval fishes which feed upon the plankton. The eel grass beds which cover a large part of the Bay may be another important source of the essential elements. In late spring and summer algal mats which cover most of the mud flats may be important to increased production within the Bay. Land drainage may also be an important source of nutrients during the rainy season. Deep ocean waters brought into the Bay as a result of up- wellings are another source of nutrients. Saddleback Gunnel. Sudden increases of saddleback gunnels were found in mats of Enteromorpha tubulosa and E. clathrata which bloomed 94 and covered the mud flat area. The saddleback gunnel feeds on small crustaceans and mollusca (Clemens and Wilby 1967). The algal mats contained a high abundance of protomedia and juvenile Crago. English Sole. English sole are believed to enter the Bay as juveniles. Breeding takes place in the open ocean (Misitano 1970 and Westrheim 1955). No larvae were collected in our plankton tows or adults taken in the beach seines. Porter (1964) found a large number of larvae in the ocean off the mouth of Humboldt Bay, yet not in the bay proper. Eldridge (1970) found two advanced stages in thirty one- half meter plankton tows taken from December through March 1969. Sopher (1969) found a few juveniles in the bay by November 1969. He reported English sole in abundance by January 1969. Misitano (1970) did not find juveniles until mid-May, 1970. Apparently, initial near-shore entry varies locally from year to year depending on ocean conditions. Entry into Humboldt is evidently earlier than in more northern lati- tudes (Misitano 1970). Misitano (1970) considered sole over 50 mm as subtidal juveniles because no fish larger were taken in his seine hauls. Misitano reported this size class remains in twenty to twenty-five feet of water in North Bay at the junction of Mad River Channel and Arcata Channel. I seined juveniles on June 6, 1972 ranging between 96-113 mm and juvenile sole up to 114 mm in late July. It was not until mid August that this size class finally disappeared from the catch. Apparently the upper size range for subtidal juveniles is not as Misitano indicated for all areas of the bay. Starry Flounder. Orcutt (1950) found that starry flounder in the size classes fed on copepods, amphipods, polycheates and isopods. Species of these invertebrates are all found around the Arcata Small 95

Boat Basin, and offer a potential source of food. They may explain the use of this area as a nursery grounds by the starry flounder. Starry flounder frequent a number of habitats; they graze in one area and then move on (Orcutt 1950). This is probably one major reason why the starry flounder was not taken in larger numbers. Stickleback and Bay Pipefish. The size classes of three-spine stickleback and bay pipefish suggest the use of this area as a nursery grounds. The adult pipefish, especially the ripe females, may indicate breeding occurrence in the mud flats. Surf Smelt. The sequence of occurrence of juvenile and adult surf smelt indicates a possible cycle of spawning within the Bay. Juveniles come in with the tides and feed on the abundant copepods, which Blaxter (1965) reported they consume. Hart and McHugh (1944) found the surf smelt spawn all months of the year. From the occurrence of juveniles, spawning appears as a late fall phenomena in Hum- boldt Bay. At the time of spawning Hart and McHugh found the surf smelt at the heads of sheltered bays. The first indication of spawning was the occurrence of a few fish off the spawning grounds (Hart and McHugh 1944). This was possibly indicated by the adults taken in low numbers this past summer while collecting for the Pacific Gas and Electric Company along marked transects in Humboldt Bay just off the Company's nuclear power plant at King Salmon. Staghorn Sculpin. I believe that staghorn sculpin were in the area in high numbers during May to feed on Corophium which were found in significant numbers at this time. In examination of the stomach contents of seven staghorn sculpin ranging from 101 to 116 mm Corophium were predominant organisms in their stomachs. In some cases Corophium 96

constituted 100 per cent of the identifiable organisms. Porter (1964) found Corophium and Amphithoidae were second or third in occurrence in sculpin stomachs (depending on the size class of sculpins).

Pacific Herring, and Shiner Perch. It seems from the occurrence of ripe adults and juveniles, that Pacific herring, topsmelt, jacksmelt, and shiner perch are using the mud flats as a spawning and nursery grounds. Hourston (1958) found the eggs of the Pacific herring deposited on vegetation in the intertidal zone from mid-January thru

April. Hatching occurred within two weeks of deposition, and meta- morphosis into the adult from six to eight weeks. He found that the juveniles remained inshore until September or October, then migrate off-shore, where they were found until their third year when they joined the spawning stock as mature adults. It seems the juveniles leave the shallows of Humboldt Bay earlier than Hourston found, though further sampling throughout the bay will be necessary for confirmation.

The appearance of ripe female shiner perch before males suggests that breeding takes place elsewhere. Apparently females and males come into the mud flats to feed, and the females drop their young. Black Rockfish, Walleye and White Surfperch. Since no adults were caught of black rockfish, walleye surfperch, or white surfperch, apparently breeding occurred elsewhere. Juveniles come in with the tides to feed on the rich plankton of the area. Phillips (1964) reports that young rockfish are plankton feeders. From underwater observations of juvenile black rockfish around the shallows of Fields Landing Wreck and the South Jetty, along with the catch in seines in the Arcata Small Boat

Basin, it appears that the shallows of the entire bay act as a nursery for this species. No black rockfish were taken in the seine of July 27, 97

1972; yet on the dive of July 28, 1972 on the Southport Channel reef young-of-the-year were first observed. A school of twenty or thirty of these juveniles were observed while diving on August 12, 1972. This suggests that black rockfish use these shallows for rearing purposes, with recruitment into the main stock beginning by the end of July. Brown Smoothhound. I believe that the brown smoothhound uses this area of the Bay as a breeding and nursery grounds. An adult, 762 mm in length which appeared to be a spent female, was taken in a gill net along with six juveniles on June 24, 1972. Juveniles were collected from the end of May through the end of July. Northern Anchovy. Although the northern anchovy spawns throughout the year (Roedel, 1953), ripe adults did not appear in the catch in quantity until June 24, 1972. Previously, two adults were caught in a gill net on April 22, 1972. This sporadic occurrence of juveniles before adults, and then larval forms preceeding juvenile forms tends to validate Roedel's belief of continuous spawning. It appears this area is used primarily as a nursery ground, though some spawning may occur. Occasional Species of Fish. The tom cod, king and silver salmon, snake prickleback, arrow goby, speckled sanddab, sand sole, redtail surfperch, larval gobiids, and American shad were all classified as occasional. Tom cod, speckled sanddab and sand sole were predominant in ten otter trawls taken in shallow water off the Georgia Pacific and Samoa pulp mills in 1968 and 1969 (Lambert 1970). It appears the juveniles of these species were brought in temporarily by the tides or were attracted for short periods of time to feed on the fauna of the mud flats. Salmon may have originated from fish released from adja- 98

cent marine fish ponds during the seining period. Crago franciscorum. Crago were measured from the tip of the rostrum to the tail. On June 13, 1972, Crago franciscorum ranging from 40-66 mm were collected brooding their eggs. On June 24, 1972 juveniles ranging from 11-31 mm were taken along with adults. Juveniles were taken in preceeding seine hauls. This may indicate juveniles are using the mud flat area as a feeding ground. Since Crago were recorded throughout the sampling, it also indicates there is a resident population in these mud flats. This information agrees with Israel (1936) who found that C. franciscorum bred between December and June, often breeding twice during the season. Post larvae range between 7-15 mm with all Crago 37 mm or less being considered immature. Spawning as well as hatching of eggs occurs in deep ocean water of high salinities. Although this state- ment may be true, the brooding Crago collected over the mud flats indicates that some spawning may be taking place within the bay. Post larval forms are said to move into shallow water less than fifteen feet in depth on soft mud bottoms (Israel 1936). This agrees with the range class taken over the mud flats. As maturity approaches the Crago move into deeper waters. Mysids. The high occurrence of mature mysids indicates breeding has taken place. This agrees with Hulbert (1957) who suggests Neomysis originates in salt water outside the bays with inshore populations increasing from migrations from maturation and reproduction in estuarine areas. Bigelow and Sears (1939) found Neomysis to be one of the regular inhabitants of the inner portion of the continental shelf. Hulbert suggests a movement of the mysids up-estuary in the bottom layer of salt water. Thompson (1970) indicates a possible two layer system in 99

Samoa Channel though enough data is not presently at hand to verify this. Because of their avoidance of light, mysid are carried inshore by the salt water layer instead of being carried out to sea by the upper freshwater layer. If this situation exists in Humboldt Bay, it occurs during the rainy season. This is precisely the time the mysids appeared in the catch. The high incidence of mysids at low tide along with the large tidal prism indicates the mysids in Humboldt Bay are also actively swimming against the changing tides which create strong out-going currents. Similar to other fish and invertebrates, the mysids are concentrated in the intertidal channel at low tide. Copepods. The presence of copepods follows the sequence as described by Gore (1971) and McBee (1971) for Humboldt Bay. They found A. clausii predominant from January through April, decreasing throughout the summer months and peaking once again in October. Their high numbers during October are a result of the phytoplankton blooms and their tolerance to lower water temperatures, ranging from 13 degrees centigrade downward. The water temperature on April 22, 1972 was 13.1 centigrade. A salinity of 29% was recorded at this time. The water temperature on May 5, 1972 was 14.4 degrees centigrade, so it would be expected that A. clausii would be decreasing in numbers and A. tonsia, which prefers a temperature range between 14-18 degrees centigrade, would be increasing in numbers. This corresponds with the data I ob- tained. On June 13, 1972, a water temperature of 17.2 degrees and a weresalinity recorded. of 28.8% This temperature and reduced salinity favors A. tonsia (Gore 1971) and is substantiated by our data. On July 27, 1972 with a temperature of 18.3 degrees centigrade and a salinity of 31.7%, as would be expected, A. tonsia ranked number one 100

in abundance among copepods followed by Harpacticoid copepods and A. clausii. On August 19, 1972, however, with a salinity of 30.5%, and a temperature of 20 C, A. tonsia were found to be only slightly greater in number than A. clausii. The high temperature which extended past the preferred range of both species may have been enough to reduce sub- stantially the numbers of A. tonsia, bringing the two species of copepods towards equality in numbers. McBee (1971) gives the preferred salinity of Eurytemora as 5%.

15% . Gore (1971) found that it withstood salinities up to 29 per cent. Eurytemora begins dying out when the temperature regime ranges between 11-17 C (Gore 1971). Gore (1971) found Eurytemora peaked with

A. clausii and the spring phytoplankton bloom; it disappeared completely by May. My data indicate its presence in fairly high numbers by the middle of June, when the recorded temperature was 17.2 C and the salinity 28%. Eurytemora did not disappear until June 24, 1972 when a temperature of 18 C and a salinity of 28.9% was recorded. It appears that

Eurytemora is more eurythermal than previous data indicate.

Invertebrate Larvae. It appears that larval Corophium, recorded on April 22, 1972 probably resulted from the breeding of adult Coro- phium which were recorded in significant numbers at this time, both in beach seines and benthic grabs. The two peaks in polycheate larvae, on

June 6 and July 21 correspond with Gore (1971) who found large numbers around these dates.

Barnacle nauplii, recorded in low numbers in plankton tows on

June 2, 1972 and August 18, 1972, correspond with the settling of barnacles I observed on the reef in Southport Channel on June 1, 1972 and

August 12, 1972. APPENDIX IV

A List of Common and Scientific Names

by Family

Fish Species Mentioned in Text

Family Common Name Scientific Name

Atherinidae Topsmelt Atherinops affinis

Jacksmelt Atherinopsis californiensis

Bothidae Speckled Sanddab Citharichthys stigmaeus

Clupidae Pacific Herring Clupea pallasi

American Shad Alosa sapidissima

Cottidae Cabezon Scorpaenichthys marmoratus

Staghorn Sculpin Leptocottus armatus

Engraulidae Northern Anchovy Engraulis mordax

Embiotocidae Shiner perch Cymatogaster aggregata

Redtail Surfperch Amphistichus rhodoterus

White Surfperch Phanerdon furcatus

Pile Perch Rhacochilus vacca

Walleye Surfperch Hyperprosopon argenteum

Spotfin Surfperch Hyperprosopon anale Striped Surfperch Embiotoca lateralis

Gadidae Pacific Tom Cad Miccrogadus proximus

Gasterosteidae Three-spine Stickleback Gasterosteus aculeatus 102

Appendix IV (continued)

Family Common Name Scientific Name

Gobiidae Arrow Goby Clevelandia ios

Finscale Goby Lepidogobius lepidus

Hexagrammidae Kelp Greenling Hexagrammus decagrammus

Ling Cod Ophidon elongatus

Osmeridae Surf Smelt Hypomesus pretiosus

Longfin Smelt Spirinchus thaleichthys

Pholidae Saddleback Gunnel Pholis ornata

Pleuronectidae English Sole Paraphrys vetulus

Sand Sole Psettichys melanostictus

Starry Flounder Platichthys stellatus

Salmonidae Silver Salmon Oncorhynchus kisutch

King Salmon Oncorhynchus tshawytscha

Scorpaenidae Copper Rockfish Sebastodes caurinus

Black Rockfish Sebastodes melanops

Stichaeidae Snake Prickleback Lumpenus sagitta

Syngnathidae Bay Pipefish Syngnathus griseolineatus

Triakidae Brown Smoothhound Triakis henlei