Fish Foraging on an Artificial Reefin Puget Sound, Washington

GREGORY J. HUECKEL and R. LEE STAYTON

Table 1. - Length classes of fish collected fromthe study area off Edmonds. Wash., betweenAugust 1977 and December 1978.

The Study Area

The artificial reef is located off thewest shoreline of Edmonds, Wash., 24

Medium and large fish lover 121 mmforallthree species) foraged more on organismsassociated with the artificial reef than didsmall fish of the same species. Abundance ofpreferred food items of medium and largestriped seaperch and quillback rockfishassociated with the artificial reef was animportant factor in attracting large numbersof these species. Conversely. medium andlarge pile perch were largely absent from theartificial reef due to a lack ofpreferred fooditems.

with successional development of organ­isms growing on the artificial reefs.

This study was designed to determinethe degree of foraging by two embio­tocids (Embiotoca lateralis and Rha­cochilus vacca) and one scorpaenid(Sebastes maliger) on organisms asso­ciated with an artificial reef in PugetSound to increase our knowledge of thechanges in the structure of the fish com­munity during the reef's early stages ofsuccessional development.

Materials and Methods

'Greater than 100 tlsh, either schooling orsolitary. observed per dive.2 Less than 10 fish observed per dive.

km north of Seattle (Fig. 1). It was builtduring the summer of 1976, and is com­posed of 88 tire modules constructedfrom 10,000 discarded tires (Walton,1979). Five different configurations werespaced in groups on a flat sand bottom,occupying a total surface area of 1,450m2 in an 11- hectare area between 10 andIS m below mean lower low water. Theartificial reef lies 60 m offshore from ariprap breakwater and 200 m south of aferry pier. Algal and invertebrate growthon the artificial reef began during thespring of 1977 (Hueckel, 1980). Thesurface of the tires forming the artificialreef was covered by a lush growth ofalgae in which a dense population ofcrabs, shrimp, amphipods, and harpac­ticoid copepods took refuge.

Field and Laboratory

All fish were collected for this studyby spearfishing between August 1977and December 1978. Collected fish weredivided into three length classes (Table1). Large numbers' of striped seaperchand quillback rockfish were observed inthe study area and were speared exclu­sively from the artificial reef. Small pileperch also occurred around the artificialreef in large numbers, while mediumand large pile perch were scarce2

•

Schools (footnote 1) of medium and largepile perch were subsequently observednear the riprap and ferry pier pilings.Pile perch from all length classes werespeared from the artificial reef, riprap,and ferry pier pilings. All fish were

121-250 '251121-250 ~251121-200 ~201

~ 120-120

120

Length group (mm)

Small Medium Large

Striped seaperchP,le perchQuillback rockfish

Species

ABSTRACT- This study was designed todetermine the degree of foraging by stripedseaperch, Embiotoca lateralis; pile perchRhacochilus vacca; and quillback rockfish.Sebastes maliger. on organisms associatedwith an artificial reef in Puget Sound, Wash.Stomachs ofthese fish species, dissectedfrom609 fish speared on, around. and near theartificial reef between August 1977 andDecember 1978, were examined and thecontents were compared with organismspresent in the immediate area.

Gregory 1. Hueckel is with the WashingtonDepartment of Fisheries. 115 General Admm­istration Bldg.• Olympia. WA 98504. R. LeeStayton is at 157 2nd St.. Framingham. MA01701.

Introduction

Fishermen and scientists have knownfor centuries that fish are attracted tosolid objects. This knowledge has beenused to increase harvests by creatingartificial reefs on sand bottoms, therebyincreasing the numbers of economicallyimportant fishes in the area.

Many factors are important to thesuccess of an artificial reef in attractingfish, including the presence of food items(Breder and Nigrelli, 1938). Fager (1972)observed that organisms growing on ex­perimental1 m cubes off La Jolla, Calif..influenced the types of predators attract­ed to the cubes. Walton (1979) deter­mined that new tire reefs in Puget Sound,Wash., attracted a higher percentage ofsurfperch (Embiotocidae) and rockfish(Scorpaenidae) than adjacent tire reefs1 year older. He speculated that changesin the fish community are correlated

38 Marine Fisheries Review

Figure I.-Study area and location in Puget Sound.

SEATTLE

EDMONDS STUDY SITE

EdmondsFerry

Terminal

,

N

l'

100m

\\

"Artificial Reef Area _~ _

Rip-rap

N

l'40km

zc...uo

speared during the mid-morning hoursexcept in winter months. Striped sea­perch and quill back rockfIsh were takenat night during winter since their abun­dance was highest during this time. Nopile perch were collected during winterdue to their absence from the study area.

In the laboratory collected fIsh wereweighed, measured. and labeled. Stom­achs were removed and preserved withIO percent buffered FormalinJ

• Due totheir extremely small size, we defInedstriped seaperch and pile perch "stom­achs" as the anterior one- quarter of theirdigestive tract. Stomach contents wereemptied into Petri dishes and examinedunder a dissecting microscope (10-30X).Individual prey items were identifIed,blotted dry, weighed to the nearest0.001 g, and enumerated.

Prey items were ranked by the Indexof Relative Importance (IRI) developedby Pinkas et al. (1971). This index wascalculated as IRI = FO(N+ W), whereFO is the percentage frequency of oc­currence of each prey item, N is thenumerical percentage of each prey itemcontributing to the total diet, and W isits percentage of weight. IRI values forprey items in fIsh from each length classwere totaled, and were expressed as apercentage of the total IRI.

The substrate from which the fIsh werefeeding was determined by matchingprey items in the fIsh stomachs to theirrespective habitats. Habitats of prey weredetermined from benthic cores, planktonnet tows through the algae covering thetire surfaces, and visual observations.Prey items were assigned to one of sixdifferent categories: 1) ArtifIcial reef,2) riprap and ferry pier pilings, 3) infauna(on and in sand), 4) epifauna (free mov­ing. in reef algae and sand), 5) planktonic,and 6) unknown. Category 2 applies toonly those prey items from pile perchspeared around the riprap and ferry pierpilings.

To correlate feeding habits with preyhabitat we assumed fIsh did not migratefrom outside of the immediate area ofcapture during feeding. This assumption

Reference to trade names or commercial firmsdoes not imply endorsement by the NationalMarine Fisheries Service. NOAA.

seems justifIed since 1) striped seaperchand pile perch were observed feeding inthe same area over extended periods oftime; 2) prey found in the anterior gutsuggest recent ingestion; and 3) a lack of

extensive migratory movements by quill­back rockfish was shown by Walton(1979). However, a few stomachs frommedium and large striped seaperch andpile perch from the artificial reef con-

June-July /982. 44(6-7) 39

tained trace amounts «0.1 percent IRl)of contents foreign to the reef indicatingthey migrated from other areas afterfeeding. Infrequent occurrence of theseforeign contents suggests migrations areuncommon.

Feeding Observations

Observations of striped seaperch , pileperch, and quill back rockfish feedingaround selected tire modules of the arti­ficial reef were conducted during 845-minute periods. Twenty stations wereestablished, each station encompassingone side of a tire module (7.6 m\ andthe sand area (15.0 m2

) immediately infront of it. During each 5- minute ob­servation period, one of the authors satapproximately 3.3 m away from the tiremodule and observed fish feeding fromthe area. Each time an individual fishtook a "bite" from the substrate, thespecies and length class of the fish, andthe type of substrate were recorded. Carewas taken not to count the same fishfeeding more than once during theperiod. Striped seaperch and pile perchgenerally foraged in small aggregations« 10 fish) so that individuals could beidentified. Once an aggregation left thestation, it usually did not return withinthe observation period. Occasionally

larger aggregations (> 10 fish) foragedfrom the stations, in which case theremay have been some repetitive counts.However, this happened so infrequentlythat if there was any repetition, we feel itdid not have any significant affect on theresults of these observations. Quillbackrockfish individuals were easily identifiedas they always remained sedentary inconcentrations of not more than 10 fishper station.

Results

We identified prey organisms from 161striped seaperch, 190 pile perch, and194 quillback rockfish from seven dif­ferent phyla (Table 2\.

Striped Seaperch

We examined 27 small. 104 medium,and 49 large striped seaperch stomachs.Stomachs from 12 medium and from 7large specimens were empty (Table 3).

Harpacticoid copepods and gammaridand caprellid amphipods dominated thediet (98.5 percent IRI) of small stripedseaperch (Table 3). We classified theseprey organisms as epifauna since theywere present in algae on the artificialreef, and in sand. Small striped seaperchstomachs contained small amounts (1.0

percent lRl) of organisms which hadbeen observed only on the artificial reef,primarily barnacles, Balanus glandula.

Medium striped seaperch foraged onepifauna (43.6 percent IRI), consistingprimarily of gammarid amphipods andharpacticoid copepods; planktonic crus­taceans (42.8 percent IRI), consistingentirely of brachyuran crab zoea ob­tained during the spring months: andbrachyuran crabs (10.6 percent IRl) andB. glandula (1.3 percent IRl), from theartificial reef (Table 3).

Large striped seaperch fed from manyhabitats. Planktonic crustaceans (brachy­uran crab zoea) comprised 38.0 percentIRI; epifauna (primarily gammarid andcaprellid amphipods) accounted for34.8 percent IRI. Organisms associatedwith the artifIcial reef structures (pri­marily caridean shrimp and brachyurancrabs) made up 13.8 percent IRI, whileinfauna (primarily polychaete annelids)accounted for 12.1 percent IRI (Table 3).

Pile Perch

We collected 71 small, 77 medium,and 52 large pile perch; 19 small, 42medium, and 39 large pile perch werespeared from the riprap and ferry pierpilings: and 52 small, 35 medium, and13 large specimens were speared from

Table 2.- Habitats of organisms identified from stomachs of striped seaperch, pile perch, and quillback rockfish speared from the study area off Edmonds, Wash., from August1977 through December 1978.

Artificial reef

ArthropodaBalanus glandulaCaridea sp.

HippolytidaeEualus spp.Heplacarpus breviroslrisPandalus danae

Brachyura sp.Brachyrhyncha sp.

Cancer oregonens isLophopanopeus bellus

Oxyrhyncha sp.Pugetlia gracilis

EctoproctaMembranipora sp

MolluscaOdosloma sp.

ChlorophytaViva spp

PhaeophytaLaminaria saccharina

Infauna

AnnelidaPolychaeta sp.

ArthropodaOstracoda ICypridinidae)CumaceaTanaidacea

MolluscaCfinocardium nuttalliiPandora filosaTransenella lantillaPolinices lewisii

Epifauna

ArthropodaHarpacticoidaAcanthomysis sp.GammarideaCaprellideaPaguridea

VertebrataCottidae

Planktonic

ArthropodaCalanoida sp.EuphausiaceaBrachyura (zoea)

VertebrataAmmodytes hexapterusClupea harangus pallasii

Riprap/ferry pier pilings

AnnelidaSerpulidae

ArthropodaBalanus glandulaBrachyrhyncha sp.Oxyrhyncha sp.

Pugetlia gracilis

MolluscaMytilus edufisCollisella pelta

Unknown

ArthropodaCrustacea spMysidacea

MolluscaGasfropoda sp.

VertebrataTeleostei sp.

40 Marine Fisheries Review

Percent Index of Relative Importance (IRI)'

Table 3.-Stomach contents identified from striped seaperch speared from the artificial reef oNEdmonds, Wash., from August 1977 through December 1978.

Small Medium Large

In 27; Oempfy) In 104; 12 empty) (n ~ 49; 7 empty)

Taxonomic Classification

AnnelidaPolychaeta sp 09 116

Serpulidae 08 OA

ArthropodaCrustacea sp. 07

Harpactlcoida 585 4ABalanus glandula 0.8 13 OAAcanlhomysis sp. 03Tanaidacea 03 05Gammandea 353 39.0 28.1Caprellidea 4.7 02 6AHippolytidae 24

Eualus spp. 21Heptacarpus brevlfostns OA

Pandalus danae lABrachyura SP lOA 46

Brachyura (zoea) 42.8 38.0Brachyrhyncha sp 02

Cancer oregonensis 07Pugeltia gracilis 13

EctoprocfaMembran/pora sp 02

ChlorophytaUlva spp. 05

-Total 998 100.0 998

Habltaf classification

Artificial reef 10 11.9 13.8Infauna 03 0.9 12.1Eplfauna 985 436 348Planktonic 42.8 380Unknown 08 1.1

-- -Total 99.8 100.0 99.8

'Greater than 0.1 percent IRI.

June-July 1982, 44(6-7) 41

We collected 229 quill back rockfishfrom the artificial reef between AugustJ977 and December J978. Thirty weresmall. 99 were medium, and 100 werelarge. Empty stomachs were found in 2small, 19 medium, and 14 large speci­mens (Table 5).

Small quillback rockfIsh foraged pri­marily on caridean shrimp, Pandalusdanae, and brachyuran crabs from theartifIcial reef (51.8 percent IRI), as wellas planktonic euphausids and calanoidcopepods (34.1 percent lRl), and epi­benthic gammarid amphipods (12.4 per­cent lRI) (Table 5).

Medium and large quillback rockfighobtained 95.0 percent lRl and 92.5 per­cent lRl of their respective diets fromthe artificial reef, foraging primarily onthe caridean shrimp. P danae, andcrabs (Table 5). Planktonic brachyurancrab zoea contributed small amountsto medium and large quillback rockfishdiets (4.6 percent and 4.7 percent,respectively), obtained exclusively dur­ing the spring months.

Feeding Observations

Feeding observations took place onfour different days in September, Octo­ber, and November of 1978. During 7hours of observations, 353 striped sea­perch, 197 pile perch, and 4 quillbackrockfish were observed feeding (Table6).

Striped seaperch and pile perch wereobserved to forage in a grazing mannercharacteristic of many embiotocids(Turner et aI., 1969; Bray and Ebeling,1975). Search for prey items was con­ducted with the head directed towardthe substrate. Rapid pectoral fIn move­ments stabilized the fish and feeding bitesfrom the substrate were quick and dis­tinct. At times fIsh were observed tofeed interchangeably from tires andnearby sand. Feeding from the artifIcialreef was primarily from the algae cover­ing the tire surfaces. Through examina­tion of their stomach contents, fish wereshown to be picking small invertebratesfrom algae shelters. On numerous occa­sions, striped seaperch were seen pickinglarge pieces of algae from the substrate,followed by rapid mouth and opercular

Quillback Rockbshthe sand (68.1 percent lRI), and bar­nacles, B. glandula: mussels. Mytilusedulis: and limpets, Collisella pelta, fromthe rocks and pilings (31.1 percent lRI)(Table 4). Medium pile perch capturedfrom the artificial reef foraged basicallyon clams, T tantilla, and ostracods fromthe sand (92.7 percent lRl) with onlytrace amounts (1.4 percent lRl) of theirdiet originating from the artificial reef(Table 4).

The diet of large pile perch spearedfrom the riprap and ferry pier pilingshabitats consisted primarily of barnacles,B. f!,landula, and mussels, M. edulis (95.0percent lRI) (Table 4). Around the arti­ficial reef, large pile perch fed less onencrusting organisms (60.4 percent lRl)and more on sand-oriented organisms(34.4 percent lRI) than they did aroundthe riprap and ferry pier pilings.

the artificial reef. Empty stomachs oc­curred in one small, four medium. andfive large pile perch (Table 4).

Small pile perch collected from theriprap, ferry pier pilings, and the artificialreef used the sand habitat for their pri­mary source of food. Benthic crustaceans(ostracods and the clam Tf'ansenellatantilla) made up 93.3 percent lRl of thediet of small pile perch collected fromthe riprap and ferry pier piling habitats,and 87.3 percent lRl of the diet fromsmall pile perch collected from the arti­ficial reef (Table 4). Only 7.9 percent lRlof the diet of small pile perch collectedfrom the artilicial reef was obtained fromthe reef. and that consisted of the gas­tropod Odostoma sp.

Medium pile perch speared from theriprap and ferry pier pilings consumedclams. T tantilla. and ostracods from

movements resulting in ejection of thealgae into the open water. This processwas repeated several times by the samefish with the same piece of algae; thiswas probably a method of obtainingsmall invertebrates from the algae. Itwas not uncommon to find incidentalpieces of algae in stomach samples ofperch.

Medium and large striped seaperchfed more from the artificial reef than didsmall striped seaperch (Table 6). Themajority of pile perch from all lengthgroups were observed feeding from thesand (Table 6). Overall, the numbers ofstriped seaperch and pile perch observedfeeding during the observational periodsdecreased with increasing size of thefish.

The small number of quillback rock­fish observed feeding may be attributableto their preference for relatively largeprey items. Feeding by quillback rockfishis probably confined to short intervalsduring the course of a day or night. Oneljuillback rockfish was seen consuminga shiner perch. Cvmarogasteraggregata.immediately above the artificial reef.while the remainder were seen eatingthe caridean shrimp. P danae. on theartificial reef.

Discussion

Striped seaperch from all lengthgroups foraged primarily on small, non­calcareous epibenthic crustaceans. Mostprey items were present on the artificialreef and sand, making it impossible to

determine the specific habitat fromwhich these fish were feeding. Obser­vations of striped seaperch revealed thatmedium and large fish fed predominatelyfrom the artificial reef, and that smallstriped seaperch fed equally from bothhabitats.

The optimal foraging theory states "...an optimal consumer should be willingto expend more energy Ior time I to findand capture food items that return themost energy per unit of expenditure uponthem" (Pianka, 1974). Assuming stripedseaperch feed optimally, the net energygained per unit of feeding time expendedby medium and large striped seaperch isgreater by feeding over the reef than byfeeding over sand. This may be due, inpart, to the larger size, or density, of

Table 4.-Slomach conlen!s idenlified from pile perch speared from Ihe arlificial reel, riprap, and ferry pier pilings oft Edmonds, Wash., from August 1977 IhroughDecember 1978.

Percent Index of Relative Imparlance (lRI)

Small Medium Large

282 549- -999 998

NIA 7.92.3 NIA

933 8734.3 4.6

99.9 998

04

0.302

0.30.3

0.3197

703 32-99.7 999

14 NIANIA 95.692.7 4353

03

997 99.9

ArthropodaOstracoda (CypridinidaelBalanus glandulaMysidacea

Acanthomysis sp.CumaceaGammarideaHippolytldaePanda/us danaePaguridaeBrachyura

Brachyura (zoea)Brachyrhyncha

Cancer oregonenSISOxyrhyncha

Pugettia graci/is

MolluscaGastropoda

Collisella peltaLirularia IirulatusOdos/oma sp.Polinices lewisii

Clinocardium nuttall,Mytilus edulisPandora IilosaPectinidaeTransenella tantilla

Total

Habitat classification

Artificial reefRipraplferry pier pilingsInfaunaEpifaunaPlanklonicUnknown

Total

'Grealer Ihan 0.1 percent IRI.

Ripraplferry pier pilings(n 19:0emply)

65.1

4.3

23

ArtifiCialreef

(n 52: 1emply)

324

46

79

R,praplferry pier pilings(n 42: 2 emply)

26911 7

0310

03

04

0483

94

41 2

999

NIA31 1681

0.3

04

999

Arlificialreef

(n 35: 2 empty)

22102

0206

51

Rlpraplferry pier pllmgs(n 39: 2 emply)

02753

09

ArtifiCialreef

(n 13; 3 empty)

34564

2.0

0.2

2830

1.2

050.2

020.7

294

1000

604NIA344

5.2

100.0

42 Marine Fisheries Review

invertebrates that take refuge in the algaegrowing on the artifJcial reef in com­parison with those found on open sand.Assuming small striped seaperch alsofeed in an optimal manner. there was nodifference in the energy gained from theartificial reef or from the sand.

Throughout this study. striped sea­perch were present in large numbersaround the artifJcial reef. Walton (1979)observed that striped seaperch wereabsent from the study area prior to theplacement of the artifJcial reef, eventhough Hueckel (1980) discovered thatpotential prey items were abundant onand in the sand. Walton (1979) also notedembiotocids were the fJrst group of fJshto colonize the artifJcial reef, even beforealgae and invertebrates started growingon the tire surfaces, and that the averagesize of early colonizing striped seaperchwas smaller than striped seaperch on theolder riprap and nearby sunken boathulls, both of which were covered withinvertebrates and algae. Observationsmade by the author on a bare, newlyconstructed concrete reef in Puget Soundshow an overwhelming majority of 8,200small to only 76 medium and large stripedseaperch. Small striped seaperch appearto be attracted to artificial reefs forshelter or orientation; larger perch aresubsequently attracted by the presenceof organisms growing on the surface ofthe reefs.

Stomach contents from small pileperch captured from all habitats, as wellas the in situ feeding observations, indi­cated a diet composed primarily oforganisms living in or on sand. TheartifJcial reef, riprap, and ferry pierpilings provided very small amounts ofprey organisms for small pile perch, yetthey were observed near all these struc­tures in large numbers. Like small stripedseaperch ,small pile perch also colonizedthe artificial reef prior to the develop­ment of organisms on the surface of thetires (Walton, 1979), and were apparentlyattracted by the cover (or orientationpoints) offered by the artifJcial reef.

Few medium and large pile perch wereobserved around the artifJcial reef incontrast to many seen around the riprapand ferry pier pilings. Medium and largepile perch fed primarily on barnacles andmussels around the riprap and ferry pier

June-July 1982. 44(6-7)

Table 5.-Stomach conlents identified from quillback rockfish speared from the artificial reef offEdmonds. Wash.. from August 1977 through December 1978.

Percent Index of Relafive Importance (IRI)'

Small Medium Large

(n - 30; 2 empfy) (n gg; 1g empty) (n ~ 100: 14 empty)

Taxonomic Classification

AnnelidaPolychaeta sp.

ArfhropodaCrusfacea sp. 0.3

Calanoida 238Gammaridea 12A 0.3 0.7Euphauslacea t03Caridea sp 85 40 lA

Eua/us spp 2.6Panda/us danae 300 715 420

Brachyura sp. 12.2 15.3 46.7Brachyura (zoeal 4A 3.3

Brachyrhyncha sp. 0.5 1.0 03Cancer oregonensis 0.6 1 7Lophopanopeus bel/us 0.2Pugetfia gracilis 02

VertebrataTeleostei sp 0.5 lAAmmodytes hexapterus 02C/upea harengus pal/as, 1.4Coftldae sp. OA

PhaeophytaLammar;a saccharina 06

-997Total 993 99.9

Habitat classification

ArtifiCial reef 51.8 950 925Infauna 0.2Epifauna 12A 03 1.1Planktonic 34.1 4.6 4.7Unknown 0.8 lA

- -Total 99.3 999 997

'Greafer fhan 0.1 percenf IRI.

Table S.-Numbers of striped seaperch, pile perch, and quilfback rockfish feeding on the sand and arfificial reefoff Edmonds, Wash., during 7 h of observations.

Striped seaperch Pile perch Quilfback rockfish

Small Medium Large Small Medium Large Large

AR'S' --- --- ---Station AR S AR S AR S AR S AR S AR S

1 10 8 5 4 3 3 3 3 1 0 0 0 0 02 6 7 1 0 1 0 1 2 0 0 0 0 0 03 12 43 2 0 2 0 1 17 0 0 0 0 0 04 14 7 7 6 2 1 5 0 4 5 2 2 0 05 6 5 3 0 3 0 0 0 1 4 0 0 0 06 2 3 2 0 3 0 1 3 0 0 0 0 0 07 7 4 3 0 3 2 3 4 3 0 0 0 0 08 4 0 4 5 0 0 3 4 0 3 0 3 0 09 6 0 3 0 2 0 1 1 0 1 0 0 2 0

10 2 0 8 0 0 0 1 9 0 0 0 0 0 011 3 11 0 0 1 2 2 4 0 0 0 0 0 012 12 8 5 3 1 0 3 13 2 3 0 0 0 013 6 1 1 0 2 0 1 1 0 0 0 0 0 014 1 1 4 0 0 0 0 9 0 0 0 0 0 015 0 5 3 2 0 1 1 13 1 0 0 0 0 016 3 5 1 3 0 2 1 7 0 2 1 0 1 017 9 2 0 0 0 0 1 1 1 0 1 0 1 018 2 3 2 0 2 0 0 3 0 5 0 0 0 019 2 2 1 1 3 0 1 2 0 7 0 0 0 020 3 8 1 0 0 1 4 13 0 1 0 2 0 0- - - - - - - - --Total 110 123 56 24 28 12 33 109 13 31 4 7 4 0

Percent 47.2 528 70.0 300 70.0 30.0 232 76.8 29.5 705 36A 63.6 100.0 00

'Artificial Reef.'Sand.

43

pilings; around the artificial reef feedingwas proportionally more from sand.Barnacles and mussels heavily encrustedboth riprap and ferry pier pilings. Initialbarnacle population on the artificial reefwas rapidly depleted to low numbers bystarfish predation and mussels nevercolonized the tire surfaces. Subsequentalgal growth on the tires inhibited bar­nacle repopulation. The small populationof barnacles and failure of mussels toattach to the tire surfaces appear tohave created a food shortage for mediumand large pile perch on the artificial reef,suggesting these food organisms are animportant attractant for these fish.

Quillback rockfish foraged more onartificial reef associated food organismsas their size increased. Medium and largequill back rockfish obtained nearly 100percent ORO of their diet directly fromthe artificial reef. Walton (1979) observedthat the average size of quillback rockfishincreased over time on the artificial reef.Small quill back rockfish inhabited theartificial reef prior to algae and inverte­brate colonization, indicating smallerquillback rockfish were initially attractedto the artificial reef for reasons otherthan food. The proximity of small quill-

44

back rockfish to small crevices in theartificial reef and their quickness to dartinto these crevices when approachedsuggest they are benefiting from protec­tion offered by the artificial reef. Subse­quently. larger quillback rockfish wereattracted to the artificial reef followingthe colonization by shrimp (Hueckel,1980).

Summary

It was shown in this study the impor­tance of organisms growing on an arti­ficial reef to the diets of three PugetSound fish species. Medium and largestriped seaperch, pile perch. and quill­back rockfish were attracted to the arti­ficial reef more by the presence of fooditems than were the small fish of thesame species. The small striped seaperch,pile perch, and quillback rockfish usedthe adjacent sand areas and plankton toforage for much of their diet, whichemphasizes the importance of thosehabitats to these small flsh. The numer­ous hiding spaces in the artificial reefwere often used by the small stripedseaperch, pile perch. and quill backrockfish as a refuge and must aid inprotection from predation. The abun-

dance of preferred food items on theartificial reef for medium and largestriped seaperch and quillback rockfishwas an important factor in attractinglarge numbers of these fish species.Conversely, medium and large pile perchwere largely absent from the artificialreef due to a lack of preferred food items.

Literature Cited

Bray. R. N.. and A. W. Ebeling. 1975. Food,activity. and habitat of three "picker- type"microcarnivorous Iishes in the kelp forests offSanta Barbara, California. Fish. Bull., U.S.73:815-829.

Breder. C. M.. Jr.. and R. F. Nigrelli. 1938. Thesignilicance of differential locomotor activityas an index to the mass physiology of Iishes.Zoologica (N.Y.) 23:1-29

Fager. E. W. 1972. Pattern in the developmentof a marine community. Limnol. Oceanogr.16:241-253.

Hueckel, G. J. 1980. Foraging on an artiticialreef by three Puget Sound tish species. Wash.Dep. Fish. Tech. Rep. 53, 110 p.

Pianka, E. R. 1974. Evolutionary ecology. Har­per & Row, N.Y., 356 p.

Pinkas, L.. M. S. Oliphant, and I. L. K.lverson.1971. Food habits of albacore, bluelin tuna,and bonito in California waters. Calif. Dep.Fish Game. Fish Bull. 152,105 p.

Turner. C. H.. E. E. Ebert, and R. R. Given.1969. Man-made reef ecology. Calif. FishGame, Fish Bull. 146,221 p.

Walton, J. M. 1979. Puget Sound artiticial reefstudy. Wash. Dep. Fish. Tech. Rep. 50, 130 p.

Marine Fisheries Review