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FISH FOOD HABITS STUDIES

1ST PACIFIC NORTHWEST TECHNICAL WORKSHOP

WORKSHOP PROCEEDINGS ASTORIA, OREGON OCTOBER 13-15, 1976 WSMWO 77-2

WashingtonSea Grani Divisionof MarineResooroes EDITORS: CHARLES A. SIMENSTAD AND SANDY J. LIPOVSKY Universityot WashingtonttG-30 Seattle9tt195 WASHINGTON SEA GRANT Division ot Marine Resources WSG WO 77-2 ss.oo UniversityOf Washington HG 30, Seattle,Washington 98195 CONTENTS

ACigfceLEIXNEMS, vl I FOREIIORD. lx INTRODUCTORYADDRE'SS, . xI I I Afonso2'. Proter

SESSIONI: PURPOSEAND SAMPLING DESIGN fJJ~ xSavaralApproaches tothe Feeding Ecology ofFishes.. CraqorIf. CoiHiat Narltlc ReefFish Ccewunitles Soae Problems and a PossibleSolution. Ia ffioftotvfC. Stainer C~ A Studyof Fish FoodHab I ts as Relatedto the Biological Enrichmentof an Area, 19 JofstS. Stephens,Jr, ard JohnP. STffson SamplingCopslderatlops In the Analysis of FoodHeb Relationships. 25 corti a. a ith InteractionsBetveen Juvenile Salmon and Benthic InvertebratesIn the Skaglt Salt lasrsh, 51 COSPONSORSOF I IIE-WOFIKSIIOP Jomaaf Cangfatonand lama@ a. Sivith FishrnesResearch liisiiiuli, Elniversily ofWashington WashingtonSea Orant. Univrrsily of Washinglon Discussion:Session I . Purposeand Sampling Design... NaliOnaiMarine f iaherieaSeiviCD hiorlhwealand Ala ka I ishenesCenlei Edilcra.Charlea A Simenatad andSandy J Lipcvaky SupporllorIhis workshop aiiripublicalicn olIhe Proceediiigs wasprovided in partby giantnurnbera D4S-158-48 arid 04-T-f58 44021 frOm Ihe Nahonal Oceanisand Atrnoapherio Adminislralion lo the Washington Sca Grani PrO- gram SESSION?: PREDATORANDPREY COLLECTION FrequencyDistributions of FoodItem Counts In Individual I lsh Stomarhs., 167 AnEva! uat lan of Ueritlilt; Irivurfebrate Samvllng Devlees for Investigat ing FeedingHabits af Fish, Sibert and., Obrebeki Jack f?. soref DS Nivaluat Ion of Standirig5loi'I s of Ma Inn Re,niircrs I laid MethodsIor Sarrpllrvi DcnersafFish In the EasternBer ing Saa: Uslng a Statir- lrnphir I'oculit for» andOb ierv lng Their llehavfar NumerfcnlBulk BiomassModel BEM. ?e.James Allen 56 T. Eaevaatuand F. Favorite P~v AStorage Rel!!eval/ProeasingSystem for Stomach Snipl ing Inter+I dul caI t 'Jursh Macrabanthos... I '19 JamesE..onif h 63 Analysisand Other Fish Data. Charles4. Simanetadand Sarrk E. Dales Fuseing Habits and SrI e t I v i' y cl P feuronactI dc c!n itic 'J ' Discussion: Session4: DataMcnlpulotlon aed I'!osantntion.. .. I SO JtrvI ~ ShelI: 6 6 rriary cf I!as!aii h In Pioui ess,, .. 6 VenJg f,. 0!truss ioii: Sessi!n ? ',.vipI liiI af Benihi!. Predatorand Prni': SESSION5; INTERPREIATIONA?ID RESIILTS line OcI? It farsr t Su !pie!4 arI "nriplI iq Tech!Iques Al ti r niir Dlet OverlapsIn Compot iiiig F I sh Papii!ation. Impressfons of tlie Beiit'ius'? 69 In the IJanalac River Est»sry.. ,139 StevenDbrabaki and John Sihart. SESSlctf I; IAuORATDIIVPRJi.f IXIRE' AIJD I OFIJTIF ICATION A Bug s Eye y lcmof Fish Predation ,147 A LaLioia?art MethodI oi !Iie Aiiaftees of f lsh Stomachr'!intent Cy r fr lsvtriae andD le»u Ne»erlebKiiak and 'Pi.' I "she't 'prosentedby TonyPhillips! - Prellrrlnary Observationson Interactions BetuaenTwa Bottam-FeedingRays and a Cosmunltyof Potential Prey MethodsUsed In studying ! aodHabits af oregan's , .153 EstuarineFI'lies...... ,...... ,...... ,...... I ~ a cublil.tonal SandHabitat In SouthernCalifornia... JohnJ<,hnaan !.l ennA. V !rifiLari stem? TheP ey of Deep-.ea Macr»aridI IshesOif Oregon.. - Prey Organismsand Prey Camsu!il ty Composition of 163 Julie Ar.!1mb Ter' 82 Juvenile Sales!oldsIn HoodCanal, Washington...,,. CharlesA. Simenst

Iv ACKNOW L EDGMENT S

This workshopwould not haverun smoothly, I f at a II, without the help of several people and agencies. First, our thanksgo to personnelof the WaslilngtonSea Orant Program at the University ot Washington,who prepared work hop ftyer- and o'lher materIals arid served as the channel for oiir f lnances. Staff of the co-sponsors,the UnIverslty of Washington'sFisheries Ifesearch Insritutu and the National Marine Fisheries Service northwest and Alaska FI-li ri"; Center,are to be thankedfor assistingwith the piannlnqand programrnlnq. SpecI a I thanksgo to WashingtonSea Br aiit CommunI catIons who coo r dI naii."I the productionof these proceedings,Joseph T. Durkin of the Hammond Laboratory,and National MarineFisheries Service for coopi,ratingwit'i the co-chairmenIn plannlnq and providlnq muchof the audio-visual equip- ment, MaryLee Brownof the samelaboratory provided invaluable assis- tance with registration, last minute details, and these proceedings. Also, HerbJenlcke, National MarineFisheries Service at AukeBay, kindly loanedus his tapiis, whichwe,"- nxccpf iona l ly better than niir own, of the discussion sess'lons. Mostof all, wewish to thank the participants for provldlnq excellent presentations and stimulating d'IscussIona. FOREWORD

Ideasfor a workshopon Food Habits and Trophic Relationships of Pacific Northwestfish hadbeen kicked around for severalyears. They coulcsc< I duringa professlona!meeting in March1976, where reglona! food habits studieswere addressed superf'Ic !ally. Our'Ingthat meotirrg,and durinrj subsequenttelephone conversations, wediscussed the need for a workshop coveringthe presentstate of fish foodhabits studies, Asa result,the f Irst Pacif I cN<>rthwesf F shI Food Habits Studies Workshrrp wasdesigned to assemble West Coast biologists currently siudy lng fish foodhabits for Informa!discussions onsampling deslqn and techniques, analysisprocedures, andcurrent research. This type of researchIs sometimesnebulous each investigator doing things just a little differ- entlyy from everyone else. However,lf seemed to us that the time bar! cometo comparenotes, to discussthc meritsof varioustechniques, and 'Ina forumfor researcherswith problems, to get the advice of reglr>naf experts In the field. Flyerswore sent to peoplewho we ihouglrt might be In! erestod insuch a get-together,Originally we hoped to hold it at Harmond,Oreqon, where the NationalMarine Fisheries ServIce maintains a field stationin arr old CoastGuard building. Fromthe numberof responses,it soonbecame evidentthat the field stationcould not comfortablyhold the group, the orirrinaiexpectation was to hostabout 25-30, but registration eventuallyreached 50 people. So the workshop was expanded to 3 days andwas moved to theThunderbird Motel in Astorla,Oregon, where confer- ence,room, and restaurant facilities wereava!Iable. Despite Its remoteness,weconsidered Astorla an appropriate setting both because of Its scenicquality and because attendees would be Ies- likely to wanderoff to moreurban temptations as usually happens at meetingsin bigcltles. Weall cametogether' with a surprisingmin Imurn of late arrivals and no-shows,on October15-17, 1976. Onegotofto the knowrrrost each importantother and resulfseach other'sof thework. workshop Conversations was that rr.soarcirersextended into coffeeand meal breaks and well Into thenight. Thiswas the k'Indof

Ix 'I s it appearsthat this workshopwas e I f I f h,d I I 11 o k h interaction we had hoped for, and apparently achieved. success and In the future. Severalp eo p le suggosf ed c hanqes an in format and new rs ex ressed the op lnlan ia wor ni Other than a general I lmlt on length ~ there was no Ital t lcular format seful. Sflii oth rs Indi f d ti, I prescribed for workshop presenfaf lons. Thus, these proceedings represent than formarmal p resentatlons wouldd bethat useful. the next one slivuld be extended 'to' o a varIety of subjects, rather loosely organized around the tive session this wor ksho p was too short andt I ha 'I at e lorine waswei I received, the topics: 4 or 5 days. Although the Astor a oca or fl for the next meetinq. consensus was f oto move another scenic lai a on or Purpose and sampl Ing design Becauseth'Is type of researcrch i prog ro ressrss lowly,new Informal Inn i s niif Sampl1ng of benthic predators and prey: ilaw different =ampler generated fast as enau gh to warrant an annua mee ng. ere that we shou I d mee f ever y other year, whicii pii and sarnpl ing techniques alter our Impressions of the benthos respondentsIndicated t a f fhe f I rst meet liig, the next workshop ln fai a 1 1978. As co-chairnen ar e Laboratory procedures and Identlf Ication or anIze the 1978session. However, we hope that by we have agreedu wi fo I orga~I be welI enougheslubl lshed fliat ia the chairmanship fhen the group w n the v*r ious countr ies and state,. Data manI pul ation and present at lon andeditorship can be rotatedamong the v*r ous hi S WarkSha r eaui I ed f rOmthe peep1 ewhO Interpretation and resu!fs f I nai i y, the success of t » p f r their work end had par I Ic Ipaf ed. The ey s shared a a special enthusiasmor e r Although they cover the present at lons, the papers assembled here vary a wI II 'Ingnessto I istento newand d'Iff ercn 'I techniques. It wa this In length, format, and overal I organization. Hopeful ly, future pro- t madethis workshopso prof It- ceedings papers wl I I be more uni forni 'In format. The discussions half ardentparticipation by eachperson tha mae of each session! proved to be so meaty and worthwhile that we have able, transcribed these from tape recordings and have Included them here pretty much In their entIrety. Charles A Slmenstad

Because this was the first "gathering of the minds", we planned to spend Sandy 0 L I povsky a great deal of time discussing methodology--and Indeed we did, Unfa- rfunafel, even though flic rnerlfs and disadvantages of various techniques were discussed at length, a standardized method < If there ls one! was nat derived. We st I I I iieed to def Irie the prey dlmens1ons and weigiits, June l971 efc.--their pros and cons, and the appropriateness of each relal lve ta the questions being asked, Therefore we strongly bel leva thai ore outcome of the next workshop should be a handbook on methadol oqy of f lsh stomach analys'is, Widespread use at such a handbook could mean that results of studies a'ang the I'aclfl~ Coast of Canada and the United States, or anywhere else, miglif be more eas'Ily compared.

Another area that received much at tention, but that could nat be suf f 1- clenfly covered involved the statist ics used In testing the s igni f lcance oi dl f ferer t prey composlf lors. Several of the best sfal' Istical analysts In th1 f laid af fended and answered many questions; however, many more quest lons were posed In the process. The next meet lng should 'Inc liide at I east one entire session on the use of stat 1st I cs as appl led I'a f Ish pr ey compositions. Again, in Impsirtani byproduct could be a han

A th'Ird Item for inclusion in such a handLeok should bo a list of useful sources, key, etc., categorized by faxonomIc groups, used lii Identifying prey organisms, Alii i Ihe workshop a urvey,hen! wa, mal leiI to sl tendai' qurryliiq them abiiii lhelr oplriions of t1ie workstiz>p and their desires for unafher one, xl INTRODUCTORYADDRESS AlonzoT. Pruter, DeputyDIrector National hfarlneI'Isher-les Servf»e Northwest Frsher'les Center Seattle, WA

I wouldlike to welcomeyouto thefirsl PacificNorthwest Fish Food HabitsStudies Workshop. I th'Ink we obviously owe a realvote of tharlks to theco-chairmen, Sandy I.ipovsky and S ISlmenstad. It looksa. If theydeveloped a rea I yIr»ter est lng, and useful agenda and g ~ther»»»I»r»I>'od p fpart I cI pants.I understandthat you ' ve come a I I theway f r»rrrr SanDiego to Fairbanks;youcould actual ly renamethis workshop pacific Coastinstead of paclflc Northwestwith no problem. They even managed to producesome beautiful weather down here. I noticethat Sl and Sandyhave such a busyschedule outlined for youthat you are not goingto havemuch time to takeadvantage of the nice weather and lookaround. That's a shamefor those of youwho haven't been to Astoria beforebecause this city andthe surroundings have a lot of Interestirur thingsto offer. This'Is the site of someImportant commerc'laI fisheri» s, rn the ColumbiaRiver and nearbyocean waters. TheColumbia River has been used In manyways over the years; to produce flshl to producesand and gravel for buildings;and as a depositfor pollutants,The expression "unique" Is overworked today but I think I ~many ways, Astoria Is uniqueand has some important lessons for everyoneIf theywill lookai the situationclosely. I'maiways happy to returnto Astoria.As SI mentioned, I slarted my careerout here about 26 years ago with the Oregon Fish Commission; In fact,some of your agenda top'Ics bring back memories. I guess my flrsl errppsureto food studies was while work'Ing for theOregon Fish Comm- issionln Astorlaand I learneda fewlessons. I recallthat one of thethings we were doing In thosedays was studying the distribution andlife historyof theblack cod. I routinelyused to ridea lot of the commerciaI t raw lers out of Astor'lathat were fish Ing for PacificOcean perch;in thosedays the depth for Irawilngfor fhernwas generally fromIDO to about150 fathoms. The black cod were quite prevalent al thesame depths and over the same substrafe as the Pacific Ocean perch sothe trawlers caught a lot of themwith the'Irperch catches, I usedto lookat andcollect scales for aqcstudies and examine a Iol of stomachsso I thoughtI had a prettygood conception nf the feedin»j

xi i I andConservation Act by the U.S.Congress a coupleof monthsago. As habttsof blackcod. Ilowever,a fewyears iater a groupof us returned youundoubtedly know, this extendsthe fishing liinlt of theUnited States with a different organization,oii a contractwith the AtomicEnergy ovt to 200miles off thecoast. T'he effecttve date of Implementation Cainmlssionto da some deep-wafer trawling off themouth of the Columbia of that 200m'Ile limit Is March1st of 1977and to complywith terms of RIverfn the ColumbiaRiver canyon,We found b'lack cod c mviionfydown that Act ft Is necessaryto developmanagement plans to governall of to depthsof 400to b00fathoms. Looking at the StcmachSfram black tlie foreignfisheries that w!Ii booccurring with'In 200 mlles of theU.S. codat thosedepths showed an eiit truly differentfssdfng sltuatlon-- after MarshI of 1977.Although the Actestablishes regional councils cannlbalfsm among other things being quite common, In the deepwater aroundthe countryto devetapmanagement plans there was not enoughtime onehad a greatsimp! if icatlonof the demsrsalcommunity of black cod for thesecouncils to be formedand develop the necessarydetailed andSebastolobus alascanus, scorpaenidrattal I s beIngthe dominant planson such a shorttime frame so the Departmentof Commerce was forins, 'I suppose,because of that greatsimplification of community assignedthe taskand lt filtered downto the NationalMarine Fisheriss structure,the feedinghabfts af blackcod were entirely different at Service--onlyfor the foreignfisheries aspect. So iiow at the Northwest those depths than In shallow water. andAlaska Flsherles Center In Seattlewe' ve beenvery busily engaged In Evenafter this episode,ln the mid-fgbU's,we did soniwof thefirst mld- developingthese plans covering nine different fisheries extending all watertrawl tng with largemid-water trawls for hakeoff Astorla,Oregon theway from the Bering Sea down to CalIfornia,including s wideverlafy andWashington, snd we learned another lesson. Tlie stomach contents of speciessuch as groundflsh, shrimp, tanner crab, king crab, snails of the hakewere qul te dl f fsreritwhen they weretaken on tlie bottomor becauseJ apanhas a smallsnail fishery in the BeringSea!, and high whenthey were taken In thewai.sr column; hake undergo dlurna I migration, seas salmon. A researcherneeds to havecomplete geographic coverage iii his samples Theksy thing that wehave to determineIn relationto eachof these to really beable to generalizeabout the speciesIn quest'lon.Other- plansIs themaximum sustainable y'laid for eachspecies and the wise,one had better conftne his Interpretationto the limited part of equilibriumyield at currentpopulations' densities, and levels. How the range with which he is dealing. In doingthis--because of the lack of data--wehad to lookat eachof Therewas another exciting discoveryIn termsof goodstudies, so con- thesespecies and fisheries as lf It existedin a vacuumandas If it troversial at the time that manypeople would not acceptlt. In the wasnot a memberof a communityof organisms that Interrelateto each early 1950's,Or. Fukvhara,with our laboratoryin Seattle,was the other,competing for foodand preying on each other, Webaslcalty Ignored f'Irst Americanscientist, to myknowledge, ta go out with the Japanese thesefactors, not ovt of Ignorancebvt for a lackof understandingof mothershipfishery ln the NorthPacific, Gulf of Alaskaarea. This the 'Interrelatlansh'Ips,arid that's notgood. The result of that ls to ls a gitlnetfishery, as many of youknow, and Dr. Fukuhara looked at realize less foodpotential fromthe particular systemyou' re looking a lot of sackeyesalmon stomachs and fovnd that theywere feeding at thanyou could realize If youunderstood the relatfonshipsbetween predom'Inantlyonfish andsquid, Many people wouldn't believe that thedifferent animals and organisms In ths system,So, to me,that Is becausesockeye salmon were known to beplankton eaters. ButIt was oneof the veryrelevant aspects of whichyou are going to bs talking true that ln that part of the Gulf of Alaskasockeys salmon do feed the rest of this week.The things you are do'lng now and in the future extensivelyonfish, smelt,myctophlds, andsquid. Again the lessonIs makeyav ail potentiallyextremely valuable contributors to the~hole prettyclear, either qual'Ify your remarks in terms of thegeographic management area. coverageof ths animal or besure that you cover the entire range of Weneed ta knowmare that Justwhat a particularspecies is eatingat the animal, a particulartfme of pointIn space.We need to knowthe food habits at differentsizes and ages, particularly at the larval stages,which Thesame sorts of tessonsemerge wlien one thinks aboutthe sampling probablyare the crftical stagesfor determiningyear class strength. gearItself. Youobviously need to knowthe selective characteristics Oneof the keyfeatures of goodmanagement ts the ability to predlct-- of the gearyou are using in orderto properlyInterpret what you see. andwe can't dothat verywell now. It seemsto methat foodstudies I seeby your agenda that these kinds of topilcsare Included and It 'Is aimedat critical life stages,such as the larva'Istages, could help us extremelyfitting for a workshopof thils sort. I noticealso that your understandthe inechanlsmsbehind year classes. In add'Itfonto year agendaIncludes a discussion of food cha'In dynamics or troph Ic classstrength, I think wsneed to knowa lot moreabout rates of trans- relationships,or eco-systemstud les or whateveryou want to call 'lt. fer of energybetween trophlc levels. Weneed to knowthe effect of This,to me,Is extreme'lyimportant and gives the neededperspective to se'lectlvefishing, ar targetingon a particular specieswithin a commvn- food habit studies. fty, onthe growth and survival of thenon-targeted species, the com- I mustconfess that I probablyfeel this wayso strongly right now petitorsand predators in thatsystem. We need to knowthe effects becauseof a personalexperience In whichI' ve recentlybeen Involved, of the physicalenvironment itself onthe growthand survival of the andam still, that hssto dow'Ith passage of the FisheryManagement elementsin the canrnunilty.When one begins to addup a'll the thingswe

XV x lv needknowledgeto know Isthroughit becomes a prettyreaI mui obvioust I-disc i thatpiinary the approach,only way tocoordlncrt achieve lngthatthe SESSlON t efforts of manyresear chers. It 's anawesome taskbut It canbe dorre and'Ithink we have the tools with which todo It. Oneofthe biggest heps is the field of eco-system dynamicsand modeling thatIs Just PURPOSE gettingpofendlalstarted.by being Iable think tothat's help us--fair Into the say. area Thisof food field studies,has a forgreat example--toIdentify some ofthe crltIcal species orelements Inthe AND SAMPLING differentsystems. I think enough is known about modeling al-the present DESIGN timeto at leastpoint us In directions thatw'Ill save usa lotof time elementsbyfilling of lncormnunitles the gaps ofthat knowledgeappear fortohave those theparticular greatest speciesImpact orordriving forcewithin the systems. I'm glad to seeyou are going to havesome discussionof this in your workshop, Soagain I certainly commend aI Iof you for coming tothis workshop. I knowdiscussed.that when Youyoumay Inot eave gohere away you allw'I agreeingI I behappy tow'Ithuse thethe samethings Identicalyou methodsbodyeisain is your doing studies upand butdown I bettheyoucoast will and go theiraway rationaleknowing whatandevery- lt seemstome with that kind of startit's oniya matteroftime until youcome tocommon agreement ontechniques andmethods, maktng the resultsup and down the coast comparable to each other,

PARTICIPAIVTS SESSION LEADER: Gregor M, Cailliet Howard Horton Richard G. Stainer John S Stephens Jr xv I Gary Smith James L. Congleton James E Smith SEVERALAPPROACHES TOTHE FEEDING ECOLOGY OFFISHES Gregor M. Cailliet MossLanding Marine Laboratories MossLanding, CA

TheInvestigation of f ishfood habl ts is becomingvery popular amongresearchers in such fle I dsas ecology, Ichthyology, andf sherl I es biology.It Is notthe Intention of thisshort paper to reviewthis rapidlygrowing field, but rather to brief iy presentseveral approache- to studyingfish feeding ecology that we have utilized In studying fishesfrom three dist'Inct habltats: the deep-sea bas'Ins off Santa B b,Clif I, I hihth ~ Idt f1 I ~hl *tllbl lf I ly~ thyI g Id I d Pt I hi ~l. It fly llyt phld ~I werestudied Ca i I I let 1972a,b!,the Monterey Submarine Canyon, where we hp I tlg t dt ~ bf fl h fh~lfl b I I Pp I tl *" lt relatedto theloca'I trap f ishery

BRIDGE HmCmlrml %%« I mOm%r~ OCEAN IO lffmmm %%0 % ~

W %OOO%%I NO.IOOmm! mmrmm%% Iwm I

I OO ~ 924m m %%m mm%~ EAH

. oro I ~ %mm!~ ~~ R %F4 mm! 'O Figure7. I .R.I. diagramsfor themore conm!on prey I temsof three O OO OO OO I AO speciesof f'latflsh at two locationsnear Elkhorn Slough from an unpublishedmanuscript by D. Ambrose!. Prey codesare not Figure5.f an andStd.Dev.! IIand 8 valuesforpreY of fourspecies explaineddue to lack of space,but are evel lable fromthe author, of flatfishfroro two statians near Elkhorn Slough from an unpub- I lshedmanuscript by D. Ambrose!. OCEAN OCEAN BRIDGE I mmmmmmm c' %mmom %%' 292 rmmmmmw W %%I ~ %OI ~ ~ ~ %%~ % ~ ~ %I%% m '%'I %I' %~ %P %P % ~ % ~ 1 I

I

".c r' I m"

Figure8. Percentby number $P! of avail ableprey taxa, proportion in diet ! R! of these taxa, and electlvity Ind'lees E! showing the !-etio of j P to gR In three speciesaf f 1atf ish from two locations near Elkhorn Slough from an unpubiished manuscriptby D. Ambrose!.

Ma or Prey Gro«pie fo MBIDrPray Graupln !B Figure6. Percent frequency ofthe major prey groups fount Inthree speciesof f la!f Ishfrom two locations near Elkharn Slough from anunpub I ished manuscript by D. Ambrose!. 13 Traphl c CampI exI ty

Narltlc reef food webs are good examples of extremely complex trophlc i ~Ier- actlons. Trophlc 'Interactions bat~can naritic reef flshe- can be concrp- tually organized Into successive degrees of Interac!ion dependingon resow direct the Interaction is. fhe only direct, or first deqree trophic lrrrr r- actlons are predator/prey relationships in which food enerqy is actuallv tranaferred frOm one organism tO another. In this camplex fOod web euCh pred- ator/prey Interaction represents an Indirect, or lower degree, Interaction at NFRITIC REEF FISH COrlMUNITIES -SOMFPROBLEMS laaSt tO SOmeextent with every Other Organism In the cornmunily, Tlrib ANOA POSSIBLE SOLUTION trophlc complexity obviously leads ro very difficult conceptual and methorlo- Iaglcal problems for those who seek to understand these corrnrunlties,

Ricrrard G. Stainer These dl f I lcutt les are further compounded when the dyrramics of tronhlc iirror- Dept. of Fisheries 4 Wildlife, Oregon Stat ~ University ~ct lons are cors i dered, Neri tie reef food «ebs are probably based mai rely on Corva lls, OR ~xogenous organ ic materfal--that which has i ls origin elsewhere. Planktonic organisms I.e. ctenophores, f ish larvae, and invertebrate lar vae! aird rvnl I pelagic fishes I.e. herr lng CZupea haz'enguaj and smelt fThafese!rt!rrfa Extensive diversity nmcnqtire nor i 1ic r lshes of the norf hcesre~n Peelf ic Oceanls characieri.,tie and apparently uniquefo rocky reef habitats MiI ler pad j frauen ! probab I y const I tuf e lhe major I ty of f hi s exogenous orgarr lc pr e- and Gelbel, !973!, Muchis still unknownabout the biology of Individual ductionn, The fluctuation of the quart I ty and qua I ity of this energy sour' e fish speciesinhabiting these reefs andabout the interactionsbetween these Is partly responsible for the dynamic nature of ner Itic reef food web.. In speries. Thepurpose of this paperis to explainhow fond habitat studies this sense, the dynam1cs of these food webs are determined by factors ext rln- can be usedto help urrder;tarrr!the communityeco ogy of nerI tie reef f Ishes. Sic to the corrnrunfty. There are also factors Intrinsic to the corrrmunliy In mypresentation I wI II attemptto developa conceptualframework for which part I y determine Its dynamic trophlc srruc ter e, one af I he eros ev i

This dynamic trophlc structure has direct relevance fo discussions of rtxr- The Communiiy Concept munlty Stability. SyStemS are Stable, that iS, they perSiSt thrOugh rrieir capacity to change. This concept ot system stability clearly encompasses The fundamentalI>asis of the communitycontopt in ecolo!y is that coextensive other meanings of stability such as environmental predictability and system popuopulaons a interact with eachot'her and with their environmentsthrough the response to external perturbations. Because community stability uitimalely transfer of energy and materials. determines the productlvfty of a nnrltlc reef community, those persons In someways It is difficult andln other waysIt Is very useful to consider responsible for manag1ng this resource should orient their Inrerests toward rierltlc reef fishes es constituents of a neritir reef comrrunlty. Thedif- understanding what regulates the stability of these communities. f i cu!t i es are mainly In corralder ing these organismsas constit uting somesort of discrete community«hich can be consideredseparately from other suchcom- Trophlc structure and composition of these cornmun1ties change on several munities. Sucha considerationwould entail muchmore information than Is scales of time and space and therefore notions of system stability must be nowavailable on the territoriality and movementpatterns of the constituent placed In some context of time and space. What regulates corrwrunlty stability species. This, however,is not within the scopeof the presentdIscussion. on an evolutionary time scale cannot possibly be perceived on dally, seasonal, Theuf'Ility of the communityconcept to the disc.usslonhere Is that, because ar annual time scales. Similarly, stability reguiaf lon of these shorter of the complexity of nerltic reef food webs,an adequateexplanation of the time scales cannot possibly be perceived In an evolutionary perspective, feedingrelationShipS of thesefish populationSiS prObrrblybest apprOached Several mechanisms have been proposed to be individually responsible for trre fromthe perspectiveof an interactingfish community VInogradov '1971!. stability of a community, Some authors consider trophlc-web complexity Increase conrmunlty stqbl I fty MacArthur 1955; Elton 1958!, whi le other cr rr- slder trophlc complexity to reduce or have little effect on community stability Turnbull and Chant 196I; DebaCh 1964; Paine 1969; !lay 1971; Steele 197'!. Others have suggested that parameters such as time-lag Wangersky and Cu»nirig- ham 1957!, threshold ferdlng responses Holilnq 1965; Steeie 1974!, Iiie history pattern Murphy 1968!, and spatial heterogeneity

14 15 WlI san19691 are the maJordeterminants of communitystabl I lty. W'Ithlnthis and weights which can be used ta back calculale relative growth rates uf framework it becomesvery confusing to discuss what Is responsible for the fish species which, within the context ol a t lsh community, can lead lo stab i I i ty of ner it 1 c reef communlt les. emp'Ir ical general lzatlons concerning interactions between these popula- tions, A mare adequate explanation of the productivity and resource utllfzatfan within these ccnysunltles wl!1 came fram accurate determina- An Approachto ConceptualizingNerltic Reef Fish Cafmnunltles tions of stock densiltiles, thel fluctuations' and how these fluctuations are correlated with environment parameters, It wiii probably be many Nlanyproblems 'In concepfualizlng nerltlc reef fish communities exist because Years before we can obtain such Information, but thIs will be a necessary successivedegrees of trophic interactions operate simultaneouslyand vary task If we are to successfully manage this resource. The utility af temporally and spatially. Data collected on the food habits of nerltlc reef Booty and Warren's Isociine theory Is that, within fhis framework, Ihe;e fishes can lead 'inductively only ta very partial generalizations concerning relationships will become much more visual and usable to us. their spatially and temporally variant relationships. Indeed,even lf data could be collected which represent' all passible states of every component of this complexsystem, the conceptualproblems In Interpretation wouldbe Conclusion almost Impossible to deal with. However, a fundamenta'Ichallenge far science Is to explain the pt>enomenaof complex systems In ail of their dynamic states. Dne of tha most important attrilbutes of such a theoretical approach is Albert Einstein 940! suggested that what ls necessary ta explain such dfver that ilt should, for Its domain, help us see the fundamental problems phenomenais a "logically un'Iformsystem of thought" ln which individual mast demanding exp'lanatlon and lt should suggest the most promising phenomenamust be correlated with theoretic structure. Theexplanation and approaches to their explanation. Thus, within a framework such as that functional significance of natural phenomenacan probablybest be understood provided by Booty and Warren's Isacllne theory, we can adequately assess In the context of a generally applicable theory. This nation is supported what questions are worth answarilng w'Ith regard to nerltlc reef fish by Carl Hempel966!, a contemporaryphllosophet af science, whowrota: cazanunIti as. It is clearly seen w I thin this framework that spatial and tempora I var let Ion of t'roph lc rel at lonsh I ps among these fish pape I a- .'If science were ta limit llself to the study of observable tlons is essential In our understanding of how these systems might phenomena,lt wouldhardly be able to formulate any precise and respond ta external parameters such as upwetilng, fishfng pressure, and qeneral explanatory laws at all, whereas quantitatively precise marine pollution. and comprehensiveexplanatory laws can be formulated in terms of under lying princlp'les, finally, It is dangerous to believe that we can ever perceive a sysfem lz, precisely as It fs and so we must remain open to new and creative Onegeneral iy appI i cabletheory, formula'led by Bootyand Warren n.d. ! ta 'P. thought and appraaches to science, Einstein 940! being th th t'- explain the dynamicsof resourceufi I ization In biological sysiems,represent> c Iaan tha t he e was, admitted that, at best, theoretical knowledge was a passI bie approachta undersfand ing these compI ex communities. Their theory "hYpothetlcai, never ccmpl etc ly f lnal, and always subJectu ec t o ques on af resourceutl I! zatlan employscomplex eats of non-iineafiso.lines proJectef-' and doubt". on successivephase planes as a time-invarianl, general explanallon of the cont lnuous f lux af interdependent var lab! es. Iliere I s gr~nt ut I I I ty of such a theoretical frameworkIn which to consider systemssuch as neritlc reef Literature Cited fish communities. This theoretical frameworkeliminates conceptual difficult- iess such as deciding whet'hera population Is regulated by density-dependent Booty, W.14., and C.E. Warren, n.d. A general theory of productivity and or density-independentprocesses, or deciding wi>ethercommunity stability Is resource utlllzat lan. Dept. Fish, Wlldl., greg. gtate Univ,, achievedby mechanismsi ~ frinslc or extrinsic ta the species Involved. In a Corvallls 57 pp Unpublished manuscript! very general way, it subsumesthe temporally and spatially variant phenomena Debach, P., ed. 1964. Biological control of Insect pests and weeds. which characterize neritic reel fish systems. Reinhold, New York, N.Y. B44 pp.

Elnsteiln, A.E. f940. Consideratfons concerning the fundaments of Applicatlan of Theory theoretical physics. Science 9I:487-492, Weare naw in the process of collecting data an these spatially and temp- orally variant faad relationships anmngfishes inhabliinq neriii reefs Elton, C.A. 1958. The ecology of invasions by animals and plants. adjacent to DepaeBay, Otegan. Arialysis of these data stvzuldprovide a Methuen, London. IBI pp, I» el iminary base for understandingthe productivi ly and resourceuti I ization wilhi» ifieSe COmmunltle.by helpinq un See whaf fnnd zeSaurceSarn being utilized by which fishes, Weare aisa callectinq otoliths, sc.dies, lengdhs, I I 17

16 HempI e, C,G. 1966.Phl losophy of naturalscience, Prent Ice Hal l, Inc., Erigiewood Cliffs, N.J. 116 pp, lolling, C.S. 1965, The functional responseof predators fo prey density and 'Its role in mlmcryand population regulation. Mem. Ent. Soc, Can. 45:5-60. Llss, W.J., and C.E. Warren. ii.d. On a possible form o future fisheries theory. Dept. Fish. Wlldl., Oreg. State, Univ., A STUDVOF FISH FOODHABITS AS RELATED Corvallls. 57 pp. Llnpubllshed manuscript! TO THE BIOI OGICAL ENRICHMENTOF AN AREA

MacArthur, R, 1955. Fluctuations of animal populations nnd a measure John S Stephens Jr John P. El I ison of community stability, E<.o ogy 36;533-536. VANTUNAResearch Group and Southern Cal I fornla Edison of Occidental College Thermal Effects Laboratory May,R.h'I. 1971. Stability in rnultispeciescommunity models. Math, Los Angeles, CA Redondo Beach, CA Bioscl. 12:59-79. Since 1966, the VANTUNAResearch Group of Occidental College has been Miller, D,J., and J,J. Geibei. 1973, urnmaryof blue rockflsh and examining the f I sh fauna of King Harbor, Redondo Beach, Ca I I forn I a. In tingcod life hlslorles; a reef ecolagystuiy; and giant kelp, 1974, Southern Cal I fornia Edison Company began sponsor Ing this research Vacrccyetie pyziferc, experimerils iri MontereyBay, CalI forn la. as a part of their research and development program In thermal effe Is. Calif. Dept. Fish Game, Fish Bull. 158, 137 pp. Eiiison discharges warm eff luent from their steam electrical generating plant Into the outer portion of tlils harbor, Murphy,G. I, 1968. PatfernsIn I 1fehistory aridthe envlronnient. Amer. Nat. 102i391-404. Utl I iz ing quent f tat ive diver I sobathl c transects run month l y at prescr ibi stations and depths within and adjacent to the harbor and at comparative Paine, R.T. 1969. A note on trophlc complexitynnd communitystability. sites an the Pal as Verdes Peninsula, Cata I ina Island, and 'In Santa Monlr Amer. Nat. I03:9I-93. Bay, we have demonstrated that both numbers of fish as well as numbers af species are significantly higher at King Harbor than at the adjacent Slmberlotf, D,S, and E.O, Wilson, l969. Experimeiital zoogeoaraphy hab Itats studied Figs. I and 2, Table af Islands. Thecoionlsation of emptyislands, Ecology50:278-295. Since 1974, we have attempted to analyze factors that could contribute Steele, J.H. 1974. The structure of marineecosysiems, Harvard to thfs observed blolaglcal enrichment, A number of factors would appoai UnIv. Pres, Cambridge, Mass. 128 pp. to represent probable sources of enrichment; therma! discharge; upwelifr from the adjacent submarine canyon; the artlflc'lal reef qualftles of the Turnbuil, A.'L., andD.A. Client, 1961, !he practice and theory of harbor breakwater and Its protection of Inshore waters, and possibly blologica! control of InsectsIn Canada.Can, J. Tool. 39;697-793 enriched food resources. The f Irst two factors, which result In con- siderable thermal diversity, have been demonstrated to affect fish comm- V inogradov, M.E. 197!, Studies In the I ife acl lvity of oceanic unity diversity Terry and Stephens 1976!. Comparative studies In biological systems. Pages 1-9 In M,E, Vlnogradov, ed. Life adjacent harbors Los Angeles, Santa Monica, Newport, etc.! Indicate thai actlvlty of pelagic connnunit!es in the ocean tropics. Israel Progr. the artificial reef quality of a breakwater does enhance fish numbers Sc1. 'Trans., Jerusa lem, 1973. and that protected waters Step'hens et al. 1974! do support large popula- tions, especially of juvenile and subadu it fish. However, as none of Wangersky,P. J., andW. J. Cunningham,1957, Time lag In prey predator the above comparative localities support populations of comparable s!ze popuI at lan modeI s. EcaI ogy 38: I 36-139, or diversity to that of Kfng Harbor, either thermal or food resource enhancement or a combination of these factors appear fo be Important !ti sustaining the observed Ichthyolog Iral enrichment.

Wfth thils In mind, In 1975 we began a study of food habI is of King Hnrhni f shes 'In order to resolve the role food resources might play in the Ichthyofaunal enrichment observed at the study habitat, Prel iminary

18 19 studies had been conducted by C. ferry unpubl.! ut I I lz'Ing surfperch examined by a variety of means. Basic growth char acterl st lcs for each populations within the harbor. Her emphasiswas placed on the function important specIes are being estimated by atol 1th examlnaf ion. Olol i the of food special fzat ion In resource dfv I sion. This emphasis is maintained fecundilty are examined on a I I specimens col 1 ected for storrrach conl enf in our current dos fgn but has been supplemented by addi tfona1 approaches analysis. Juven1les of sel ected groups of ecolog lca I Iy important specI es whlch are more spec I f Ical I y directed towards the total enrichment piet ure. are being maintained ln our laboratories and w II I be used during the next Resource separation certainly can enhance diversity and perhaps allows year ' s food convers ion stud I cs. T'hese s iud i os w II I be carr fed out a I mare effective resource utllizatlon, therefore the maintenance of more three temperatures representing the thermal variation wl thin the harbor. dense fish populations. Observations of resource separation llrrough Estimates of food util lzatfon using prepared standardized foods! wil I stomach content analysis and fish feeding observations alone, however, be developed. During Year I of thils study' Ehrlich restricted his cannot' satisfactorily resolve these possible effects though they may efforts to grunion and top srrrelt because of ease of rafsing these fish demonstrate conclusively that resource separation exists. from egg ta adult. He was able to show a strong correlat1on between preferred temperatures and assimilation efficiency Ehrlirh, pers. rorrm.!. In 1975, we began a mul tifareterl approach to food resource problems in Estimates of food conversion can then ult1rnately be correlated wllrr KIng Harbor bbsed an Catlry Terry's original work with the Emblotocldae. feeding observations I.e. bites/minute!, grazing observations epifaunal The first phase involved expansion of her gut content studies to al I growth with and without grazers!, fish growth, esilmaies of biomass of col lectabl e ici~thyofaunal elements ~ in order to place her original harbor fish populations, and estimates af reproductive energy drain and observations within the total framework of the "harbor communltyn, fish recruitment.

Specimens were col I ected for stcmach content anal ys Is with gl I I nets, The afm of this study Is nat wanly to del ermfne the role that food re- spears, and traps, lish feeding habits were analyzed by rllver observation sources In King Harbor might p Iay In the ichthyofaunal enrichment ol fhe and underwater cfnephotogr-aptry. Approximately 30 of 45 commonresident area, but to u It ilmately develop an i chthyocurnmunI ty resource model a Ionq specfes are included within these analyses. At present we have developed the lines developed by Parrish 975! which wi I I define the role, if a preliminary classification of King Harbor fishes using four basic any, that thermal effluent plays iln this system. categories: eplfaunal grazers, pesclvares, planktlvores, and herbivores Table 2!. We are now subjecting these data to discriminate analysis utl'llzing Occidental's IBM 376 computer. Literature Cited

Dietary preference data will also be run against Edison's data collected I err I sh J D 1975 Mar lne Troph! c Interact fons by Dynamic S imui at ian on invertebrate distributions within the harbor. In add fon, our of Ffsh Species. Fish Bull., 73: 695-715. divers are seasonaliy sampling the epifauna to give us a qualitative Index of changes In invertebrate canlrrunlty structure. Previously Stephens, J.S., Jr,, C.B. Terry, S. Subber, and J. Aiierr. 1974, determined fish distributional data depth, temperature, habitat, Abundance,Dilstrlbution, Seasonality, and Productivity of the season, etc. can be correlated with toad resource distributions; a Fish Populations in Los Angeles Harbor. 1972.-73. Allen llancock high concordanceof these data would appear to reflect an interdependence Foundation and Sea Grant PublicatIon. 42 pp. of d Ist r I b ut I ons. Terry, C.B. and J.S. Stephens, Jt. 1976. A Study of the Orientalion of Periodicity of feeding activity has been rnvestlgated by both diurnal Selected Emblotocid I ishes to Depth and Shifting Seasonal and nocturnal diving surveys. 'Levels of eplfaunal grazlrrg, the dominant Vertical TemperatureGradients. Bull. Sa. Calif, Acad. Sci., feeding fn King Harbor, are being investigated by fish exclusfon experi- ln press. ments. The effects of fish exclusion cages on unmodffied eplfaunal growth as well as eplfaunal establishment succession! are being examined at several depths and localities with the harbor. Our ffsh cage experi- ments are supplementedby regular diver observations and detained stomach examinations of species observed as Important grazers ln the area of the cages. Analysis of the caloric content of major epl faunal dietary elements began In 1975. These bomb calorimetric studies wl I I continue seasonal ly and as adequate quantities of food Items are collected.

Levels of food intake, assimilation, food conversion, and growth are being

20 21 Figure I . Average number of f I sh observed per transect at King Harbor and Palos Verdes. K I V .e.s s.rKs rs~ I I. Numberof species ann meanabundance at KIng Harbor compared ,orr to Palos Verdes and Catalina Island IQI ~SI ~ I-i 477 mean/station mean/transect S-447 mean var. mean var.

King Harbor 19,1 30.8 12,4 20.6 «QQ KU Palos Verdes 13.4 7.8 8.4 1.4

Catalina Island 14.7 6. 5 K 10.6 2.6 7 ZQQ

IQQ Ind I v I duaI s

number/ number/ mean/station mean/transect station transect KQIITH mean var. mean var.

Figure 2. Number of fish species observed per King Harbor 834.4 206116 245.0 28497.6 72 198 transect at King Harbor and Palos Verdes. Palos Verdes 308.5 71001.4 108.9 9384.9 6 21 Catalina Island 572.4 43059.7 157.2 4898.6 22 100

IP I- 4 4 e 47 ss44 b 4 a

Kss4II Pe polesVsress

K 4 Q ~sr sess 4 I I Is 4 Is J I 4 4 Q II GsI 4 F I'GKIH IPI4

22 23 Table 2. Trophfc categories of fish trom KIng Harbor using pret imlnary dietary analysis data>

Seconder Carnivores, etc. Herbivores Pianktonotro hs Grazers enerai! Predators SAMPLINGCONSIDERATIONS IN THE ANALYSIS HermosiZZa Hngraulie Bhacochi lus Paralabraz OF FOODWEB RELATIONSHIPS Cirella A! Chrvrmis toeotee clathratue" ffedialuna A! Seriphus Phanerodon Paralabrax Gary B. Smith Hypeoblennius Sebaetee furoatus nebulifer Q, T lfat I oneI Mar f ne F rsher f es Service gilberti mystinus J ! Hypsurue Parala br

25 "4 size of the eyes,and the structureand size of teeth, jaws, andgill Interval rakers DeGroot, 1969;Yazdan I, 1969;Gosl Ine, 1971;Ebe ling and Callllet, 1974, Hobson, 1974!. The me0hodof samplInq must be evaluated as a potential sour~a of blas. 5peclmens coiiected In towed net samplers plankton nets or trawls! 13ehavloralobservat lans in fhe f I aidand laboratory can also provide kcy may feed an unusual prey with the net, or have unusual items lorced int!! Informationfor the claSSIf icat Jon af feedingroles: howis foodobtained, their guts Judklns and FIeminger, 1972!. Samplingmethod and dlffr ran- andwhat are the act'Jvltycycles of predatorsand prey7 Is the predatoran effects of sampling depth must also be considered In assesslnq the actI vesearcher, or doesit sit andwait? Areprey se J ectedv lsua I ly, occurrences of empty stomachs. or by tactile perception? Is feeding off- or on-bottom? Theselection of samplesilze far determinatlansof proparfions of prey If sampling Is to becon!Iucted examlninq food composl t ion and/or feeding occurrences can be based upon a reiatlon of sampling theory and survey rates, then an Important behavioral observaf I on ls the determination of objectives for preclslon of estimates Cochran, 1963!. The frequency of predataract'Ivlty pafturns. does aadlnqfni lowa dial cycle, or Is It occurrences/non-occurrencesof a prey specieswithin stomachsamples continuous'7Numerous ate and Clelland, 1959!. andWei sh, J 968;l absan, 1965, 1924; Hshould be recognizedas d'Istlnctly different from estimatesof feeding rates. 1. Iieting of Food Items; Vhct is eaten? Thechoice of the units of measure numbers, volu!nes, wet weights, airy In the simplest analysis, feed'Jngrelationships can be describedas the weights, elementalweights, or energyequivalents! mustbe basedupon I 1staf p!ey speciesfaund within predatorstomachs examined. A measure a relation of researchobjectives and cost. It Is Importantfo recagnize of the f idellty of eachconnection Is fhe food Item's frequency cr fhat d if erent I ypesof measurementsmay g Ivs markedI y d Ifferent results proportion>of occurrencewithin stomachsamples. Holden and Raitt, 974!. If meaningfulresults are to be obtaJned, caretul attent ion mustbe BIases In the dei'ermlnation of relative food composlilon inr Jude: givento surveydes ign Cochran,1963! . A specI f lc targefpopulation I ! read I! y digested prey may be underestimated; ! problems in tiie mustbe Identified, andrelated to variafions of predatorand prey In enumeration and measurementof f ragmentaland amorphousmateri a Is bothtime andspace. >hedistr ibut'lonof sampling,and sampling effort mucus,detritus, chItin, bivalvesiphons, etc.!; and! the potential =numberand s Jzeof sampI es!, must be related ta averalI research Influences of discontinuous feeding patterns must be considered. obJectIves. Randomizationshould be Incorporatedso that each Individual fish In the target population and samples! has an equalchange of B. Feeding R!ztee! Bo a much ie eaten? selection. Asopposed to the collection of large single samples,the useof smal er Interpenetrating subsampfesenables assessment of variance Although the Impl led objectives of most feeding studies are to determine within sampling periods. feedJng rates energyor materiaI f lux t-l, or prey mortality I. ! and the relative contributions af Individual foad sources to these rate Sincethe qualitatlve compositionof food ingestedIs frequentlyrelated few studies of marlne fishes have convincingly estimated natural rates oi to predatorsize Ty er, 1971,1972; Daan, 1973; Jones, 1975!, It Is food Ingest I on or predat ion Lasker, 1978; TrevaI I ion FTAL., 1970; often desirable to subdivide the sampledpredator population on the basis Dean, 1973!. af size class ntervais. The size of the sampletaken fram each Interval shouldthen be proportional to the numberof Individuals within eachs'Ize- food consumptlan rates can be esf imated by three principal approaches;

26 27 peGroot,S,J, 1969. Digestlve Systemand Sensorla i Factors In Relation < I! direct measurement» of prey abundance before and after predator to the Feeding Behavior of Flatfish Pieuronect I formes!. addition/exclusion I. of Prey Selection Hobson,E.S. and J.R. Chess. '1976.Trophic Interactions AmongFishes and The terms "specialist" and "generalist" have frequently been used to Zooplanktersnear Shoreat SantaCata'Iina Island, Cd»lifornla. compare the feeding characteristics of different predators. With ln- Fish. Bull,, U.S. 74: 567-598. surveys, these descr I pt lans have meaningful applications with def In lt ion! for comparing the number of prey species, d lstrlbutlon of amounts of HoldenP J.J, and D.F.S. Raitt. 1974. Manualof F lslieries Scierire, Part each prey, and range ln prey sfzes observed among different foragers. 2. Methodsof Resource Investigation and TheIr Application. Meaningful use of the terms "select ivlty" or "food preferences" must be FAO, Fish, Tech. ~Pa. 115. 214 p, assessed in the context of relative prey availabllitles. Relative Jones,R. 1975. SomeObservations on Competitionbetween Some Gadold prey availabliltles may, or may not, be related to prey abundances. If Fish 'pecies. Symp. Changesin North Sea FIsh Stocks and comparisons are to be made of food resource use and division between Their Causes, Aarhus, Paper No. 48: 1-10. predators, stomach analyses should be restricted to individuals co- occurrlng within samples Jones, 1975!. Judkins, D.C. andA. Flemlngcr. 1972. Comparisonof ForegutContents of SPE t SI III Ght I df ~ tCII tl dAIA* Stomachs. Fish. Bui l., U. S. 70; 2i 7-223. LITERATURFCITED Keast, A. and L. Welsh. 1968. Daily FeedingPeriodiclties, f'oodLiptak Al len, M.J. 1974. Functional Structure of Darnersal Fish Communities. Rates, and Dietary Changeswith Hourof Day tn SomeLake Fishes. Southern Cal I fornla Coastal Water Research Project, Annual Report. J. Fish. Res. Bd. Canada 25'. 1133-1144. p. 69-73 Lasker, R. 1970. Uiiiizatlon of Zooplanktonby a Pacific Sardine Allen, M.J. 1975, Regional Variation in the Structure of Fish Communities. Popuiatfon In the California Current. In Steele, J.H, ed!. Southern Californfa Coastal Water Research Project, Annual R~eort Marine Food Chains. Oliver d Boyd, Edinburgh, p. 265-284. p. 99-102. Pearcy,W.G. and J.W. Ambler. 1974. FoodHabits of Deep-SeaMacrourid C h, W G. 1963. S~tl 7 6 Ict . Wil 9 I 5 N f 413 9 Fl h ff th 0 g C t. ~0-3 fl . 77: 745-759. DprandN. 1973. A Duantitative AnalySI s of the FOOd intake Of NOrth Sea S th d. 7 R 6 1975 ~EI I I M t'I 4 . Ch 9 *~ 6 ff II, 1 d. Cod, Gadus rrrarhua. Neth. J. Sea Res. 6: 479-517. 391 p. Davis, G,E, and C.E. Warren, 1968, Estimation of Food ConsurnptIon Pates. In Rlcker, W.E., ed!. Methods for Assessment of Fish Production in Fresh ~aters. IBP Handbook No. 3. P, 204-225, 29 28 Tt.MW.W ~ C.CI II d.1959,~dtf dSh t tSttltl« INTERACTIONSBETWEEN JUVENILE SALMONANO BENTHIC INVERTEBRATES Interstate, Illinois. 171 p. IN THE SKAG'ITSALT MARSH

Trevalllon, A., R.R.C. Edwards,and J.H. Steele. 1970. Dynam'Icsof a James L. Congleton and James E. Smith Benthic Bivalve. In Steele, J.H. . Marine food Chains. WashingtonCooperative Fishery ResearchUnit, Callege of F'Isherles Oliver d Boyd, Edinburgh, p. 285-295. University of Washington, Seattle, WA Tyler, A.V. 1971. Monthly Changesin StomachContents of Oemersal Fishes In PassamaquoddyBay, N.B. Fish. Res. Bd. CanadaTech. Objectives, Sampling Oeslgn, and Prellmilnary Results ~Re. 288. 119 p. This pas ast spring and surrmrerwe conducted preliminary sampling of fish and Tyler, A,V. 1972. FoodResource Dilvls ion AmongNorthern, Marlne, berrthlc invertebrates 'In the salt-mudflat system of the lawer Skaglt R iver Oemersalt I shes. J. Fish, Res. Bd. Canada29: 997-1003. In Puget Sound, Washington. During the spring and summermonths, the nu- merous small tidal streams that dissect the surface of the delta In this Wl, W. 19th. Sff t f ~ft 9 t th I ~C area supported very high populations of starry Flounders Ptfzt chtye Springer-Veri ag, N.Y. 298 p. etc[ lrztrre!, staghorn scuiplns Mptcccttue azwrratue!~ three-sp'Ine stlckle- baCkS GrZeteZVreterreacrrlerrtrre!, and the juvenileS af Chum Orrcanhyrrehue Windell, J.T. 1968. FoodAnatysls andRate of Olgestion, In Ricker, keta!w chinook . tehrmrytecha!, and pink . gcrbrrechWz!salmon. The pur- W.E. edi. MethodsFor Assessmentof fish Production In Fresh poseof our samplingwas two-fotd. First, we wantedto obtain a general Waters. IBP HandbookNo. 3. p. 197-203. p lcturec ure ofo utl I ization of the delta area by fish and to assess the impact o fe their predatlan an populations of the benthic Invertebrates which ccm- Yazdanl, G.M, 1969. Adaption In the Jaws of Flatfish Pleuronectlformes>. prlse a large proportion of theilr diet, Second, the study allowed us t o J. Zoot. Load.> 159: 181-222. evaluate various approaches to sampling which may be useful for future research. In this preliminary work we have concentrated our efforts on juvenile chum and chfnook salmon.

Fish sampling techniques After experimenting with traps and with a 25-m beach seine, we found that a 7-m wide by 2-m deep beach seine with I/8-Inch meshwas both effective and practical. It was light enoughto carry on foot, and suitably sized far sampling 5-to 10-m «Ide ttdai streams. Most af our sampling was done in Index Slough, near the South Fork of the Skaglt River. Weestablished 6 stations at 80-m intervals along its length and made 10-m hauls during low tide periods. The effective spread of the 7-m seine was about 5 meters. Fish were Ident'Ifled and counted ln the field. Selected samples were subsampled; the subsamples were preserved and returned to the lab for diet analysts and length-frequency measurements.

Results Large numbersof chumand chinookwere present In the tidal streamsin late Apr' rll and early May. There was a sharp decline ln early May Figure Ii; the peak outrnlgrat ion may have preceded our Inltla'I sampllng. Our pret lminary diet anatys'Is of chumsalmon Indicated active feeding in the tidal streams. The values for percent ful iness of stomachs, shownin Table I are general ly quite high, although the f ish at station 5 had nat fed as much as those at the other 2 stations. Since station 5 had the highest ish density, tt ls tempting at thlS t'Ime ta speculate that this dtfference may reflect Intraspeciflc competition. 30 At severe I fi s hsamp ling stations we have established 4 transects alonq Most of the dist Items fefl into each of whhl c hwe t are a kingng 5 benthic cores at mont ly to bimonthly interva Is. three categories: Two of these transects are located wfthln the stream ln ares of prssumamabl y 100 1. Corop&umeafmovt'e, a tube dwel- high predation pressure, and the other 2 are pieced on the adjacent marsh, ling amphlopabundant ln the h redatlon pressure fs assumed to be relatively low. Fish sampling in 50 de I ta. tidal streams will continue to be by seining at low tide, with add tlonal trawling or co I I ec tin ing by other methods on the adjacent marsh and mudf fats 2. Harpactfcafdcopepods, which were at ghl h tide to quantify predatfan pressure outside the streams.. m . A A d dla agram- ram- Important numericall y In the metic representation of our sampl ilng scheme Is shown in F igure 2. stomachs, but accounted for less than 5$of the total dry weight 10 of the diet . 3. Adults, larvae, and pupaeof insects. Oursprilng sampling has led to many specific questions about the effects fish predation may have on the in- vertebrate populations. For example: What fs the Intensity of predatlan Apr,30Nay 11 N~ay7 ~y 31 and what Is Its effect on the abun- danceand sfze distribution of prey FigureI. Esflmated densilty of organisms, both in Fidel streams and pjgure 2. Typical 1ndex Slouch section abowtng juvenl I echum and chinooksalmon on the adjacent marsh7 Can the In- aefne core sample and travel traneeera In index Slough, Spring, f976 vertebrates In tidal streams support Fish per IOOm2 this predation pressurethrough re- productionalone, or does Irrrnfgra- tion from the flats play a role In Samp Ifn ng wwlif be conducted throughout the next year to monitor fish popula- maintaining tidal stream invertebrate populations'. tl ons an nd to gather data on Invertebrate populations before, durin ' g, and after the strong spring pulse In predator abundance. Evenv ntu ua II y w we ho p e to Planned future work refine this approach to estimate the carrying capacity of the salt marsh for juvenile salmon. Toanswer these questions, basic Iffe historyilnformation f' required for the preyspecies concerned. We are obtaining this datafrom two sources: ffrst, studieson the carrwrunity structure of saltmarsh benthic Invertebrates;" Application of Information to Fisheries Management Problems second,benthic sampling conducted concurrently with our fish sampling. Mast of the streams and rivers entering Puget Sound have--or once had--salt TableI, Fcregutcontents dry weight as percentdry bodyweight! of chum marsr h ss oOf g reater Or leSSer eXtent In the tldevater Zone. All Of theSe salmoncol lected from 3 IndexSlough Stations on Apr1 I 30, 1976 streams and rivers also support runs of one or morere o of p the 5 s acies of Pacific salmon, Fishery bfologlsts have sometimes noted large numbers of STATION juvenile salmon in sa'lt marsh streams R. Orre'll, 1976, personaI cornrrunfca- S.D. RANGE ttl on ! b u t svvldence e for utllfzatlon of marsh food resources by salmon has been lac kl ng. . 0 ur I nItlal samplfng on the Skagit River delta spring, 1976! 10 3.88 indicated that large numbers of chum and chinook fry werer f fee edln ng In n e the 10 5.18 I . 96 2.46 7.71 marsh. Wedo not yet knowhow long the fish reside In the marsh, or what portion of t t o a I c hum d an c hinook outmlgratlon is Involved. However, the 10 2.04 I .62 0.18 - 5.04 high density of fry observed fn tidal streams fn late April rang nq rom 200 to over 800 fry per IOO m at some stations! and the higher percentage f fr with full stomachs suggest that the Skaglt salt marsh may be an Im- portant foraging area for downstreammlgrants, More detailed e a e Information on the feedln of salmon fry fn salt marshes wlii be valuable to agencies "Ph,D. Thesis research of J .E. Smith with responsibility for managementof salmon resource, for several rea~ons,

32 First,if survivalof outmiqrantsis enhanced bythe presence of salt marsh habitat,this provides a strong argument forpreservation ofmarshlands. In A tabulat o n of al I the publ I s~aI d I iterature would undoubtedly demon;trate theabsence ofhard evidence weighing Infavor of marsh preservation, a that over 95 of the research comp et ed on sasaimanid fis'hes ' ' has de~it «i i I largeportion ofPuget Sound's marshlands havealready beendredged, fii ed, the freshwater p hase of the I I fe cyc Ile. . Y e, t mortalftymo rates during the orotherwise altered. Reclamation afthe Skaglt de tafar farmland began ln estuarrlne ne or "early caasta!" phase of o e the life e y cycle are believed to be ex- the1800's; today less than twuniy percent of the origina marshes remain. treme I yhl g h and very var I abl e from rom year to year IParker, 1968; Ro oya al Iu i?I TheGreen and Puyallup River marshes havebeen obliterated byindustrie BespIie the technical d Ifflcultles,cu e much more effort must be put n o development,andmuch of the Snohomish RIversalt marsh hasbeen altered by Identifying the factarst th a t edetermine erm the estuar'Ine survial o fj 'uvenile landfills andlog raft storage. Because ofcontinuing piassure fordevel- salmon. ofopment salt of marshes remaining is essential.delta areas, documentation of theecological importance f 11ER*TURf C ITED Thesecond major point I. thatunderstanding ot Interactions be ween Juve- n1I esalmon andtheir prey in the sal t marsh,andbeyond inthe main estuary, Fei ier, R,J, and V.W. Kaczynskiski .. 197'5. Si ' zee select lwe predation by juvuni .ni le Ie wouldiacilitate devetopment ofoptimal rearing-and-release strategiesfor chum cafmon 10nccrh nchua Petal on epibenthic prey n uge artificiallypropagated salmon, For example, thetiming of releasesof J. Fish. Res. Bd. Canada 32: 1419-1429. hatcheryfish shoutd be such that adequate natural food ls availablewhen theyenter the estuary, At present we know very little aboutseasonal Parker, R.R. 1968. Mat Ine mormar alit a i y sc SChedules Of pink Salmon Of the Bella changesi nthe abundance ofestuarine preyorgan I sms, In< ontrsst, Japanese Coola River, Central British Columbia. J. s . es. chumsalmon culturists are reported to carefully moniltor the abundance of 25: 757-794. zooplanktonilnnearshore waters and to releasefry only when conditions are judgedfavorable fortheir survival. It Isnot possible tospeclflcaf y Royal, L.A. 1962. S urv vlv va I In n the estuaries, a most critical phase, Identify the benefits derived from th sprocedure, butcerta nlytheJapanese Western Fisheries, September 1962. pp. 16- I chumsalmon program hasbeen anoutstanding success, andhigh fry-to-aduft survival rates have been achieved. 0nvelopmentof opilmal release strategies for hatchery fish will alsore- quireeknowledge of the carrying capacity of salt marshes andof thelittoral theirzoneinfeeding theestuary, activity «here Fe Puget lerandSound Kaczynskl, chum and1975!. pink salmonFoad availabilityfry concentratein saltmarshes andin the littoral zone may constrain thenumber of fry that shouldbereleased Inany river system orpart of the Sound. Although pro- ductionnof«ild chum andpink salmon Inthe Puget Sound region fspresently muchbelow historfca peak levels, artificial propagation ofchum salmon may ilncreaserapidly from the present level of about 20million fry per year to over500 million fry peryear within the next decade. The f lsquaily River systemalone ls believedto have enough available spring water to Incubate 600to 700million chum eggs. Mare realistically, ff the number ofchum fry utilizingthe f isqualiydelta Is Increasedby150 to 200million, how will populationsof preferred prey organisms, suchas Comphium ealmcnie, be affected?And If thegrowth and survive I of fry ls progressivelyreduced dueto increasedlntraspeclfic competition for food, at «hatpoint will ad- dlflonalinvestment Inhatchery facilities cease to becast-effective? Theseare important questions, since a "crash"enhancement programcould easilyovershoot theoptimal production level. The return af adultsfrom a releaseof chum salmon fry Is notknown for4 years,and even a strongdown- «arttrend In fry-to-adultsurvival would not be conclusive without 4 ar5 yearsof data. Hence,a rapid expansion of hatchery fac!Iitles could contleveli hasnue without been exceeded.contravention for9 to 10 years after the opt Imal production

34 35 Juvenlle salmonIn estuaries. Hecited the caseof the ColumbiaRiver where freshwater predators end 20 ml les upstream of the mouth and sa I I- water predators don't usually enter the estuary. If predatorsare the cause of the mortal itfes, might they be yearl lng f fs'h feeding on the downstreammigrants? Or perhaps might the mortal lties be related ta ava I lab f I fty of food? Durkln continued the discussion of availability af food as a limiting factor by suggesting that perhaps the yaung chinook and chumwere over- utlilzing what ls available, He thought that perhaps the fish fed on Cezxrpfrirrmsa]rrkrrris

Joseph Durkln ~ondered what might bee caus I ng obser ved mor t aI I ries of 37 mentas feeding groundsmight be the basis for r e as s or preserving these areas. He wonderede any If an studiess udlesexisted where such nearshore habftats did not Callllet mentioned that he had used a slmflar net to study assemblages exist but wherepink andchum fry exist, feedln erh of fish associated with draft kelp In Monterey Bay, California. They Heaisa wondered lf feeding ina nearso e en ro en wasactus fy part encircled the drift kelp wfth a small Boston whafer and pursed the bottom e r e hlstor1esor merelyan adaptatlan to a articular ment. Conglefonthought that fiI o a par cu ar envlron- up a sh were able to adap t eto the resourcesr withiln a particular ecosys stem. sm. lier erb ert Jaenlckeasked haw lang chum fry Slmenstad returned to an earl I sr thought about food being a I lmitirrg w rema n In theseshallow, estuarine areas. Heth It .d th factor ln early life histories of fish. He emphasized that rates and Bristol Bay wherhere socksyesmolt move several hundred mlles siawl In cold rations have really not been studied at all. Same literature on rates sunrnersbut faster fn warmsummers. Thiss speed of rnlgratfa» seemed to an

39 CaI I letsupported this by saying that there ls aiso a considerablegroup of I Iterature coming from the f lshlarvae culture section at National MarineFisheries Service In LaJolla, Callfornla ReubenI.asker and John Hunter!.ffe especial I ycited papers on Engrautf'e mordaz, Most of the work Is laboratory work. Congletonmentioned that veryfew researchers have tried io combinefield andlaboratory studiles. One mfght, for example,get estimatesof evacuationrates In the laboratoryand apply them to consumptionrates derivedfrom actual field observations.Slmenstad agreed thai simultaneous studiesof a communityshould be Initiated. Prey corrnrunlty composition Is a very important thing to know. Laevastusuranarfzed by saying that studyneeds had been aired but we oughtto orderthem by priority. Hethen suggested that might be one of the goalSof the filsh foodshabits studies workshop. Oneof the Ilmltfngfactor s of anystudy, of course,fs funding.Re- searchersshould carefully consider the benefit/cost ratios of any proposaland use research time and dollars wisely. AN EVALUATIONDF !3ENTHICINVERTEBRAI E SAMPLING DEV ICES FOR INVESTIGATINGFEEDING HABITS OF FISH

Jack Q. Word Southern California Coastal Water Project El Segundo CA

Benthic invertebrate samplers and the information gained from their use can be extremely valuable to research conducted on feeding habits of fish. These samplers provide complete and undamagedspecimens which can be accurately identified, and the data produced can be used to formulate detailed pictures of the communityof organisms present In and on the surface of the sediment. This evidence of exist'Ing community structure coupled with Inventories of the stomach contents of particular fish species can be used to determine select lv'Ity In patterns of feeding for the fish species in question. How- ever, manyof the benthic samplers in use today do not function In the same manner, and as a result, unequally represeni both the types of specIes and number of Individuals captured. Therefore, data are somewhat b1aserI by ihe type of samplingdevice employedand caution mustbe used ln attempting direct' comparisons betweenorganilsms foun4 In the stomachcontents of fish and those depicted by corrmrunitymembers In benthic grab samples. The pur- poseof this paper Is to review the results of a field comparisonof benthic samplers and to discuss the inherent attributes and problems associated with several types of commonlyused sampling devices as they relate ta research on fish feeding habits. Our study focused on three major types of benthic sampierss: benthic greb samplers eg. VanVeen, Smith-Mclntyre, Ponar, Slrlpek, and OrangePeel!, deeperpenetrating samplingdevices

Figure Ia. Orange Peel Figure If- Smith-hkclntyre Figure lb ~ Bar frlpeed Van Veen

I i qure I d. Pnnar

FIgure Ig. Box Corer 45 Methods

Cur field s t udy wasconducted dur ing 2 crufses In th I t. f 1974 Word et al. e w n er o and 1975 e a . 976!. Biologicaldescriptions af an areaofo o bott om are di rect- p n uponthe numbersand kfnds of organismspresent in benthic samples.Focused on; 'I! Horizontaldistribution patterns Investi t d b takln g epl '!0 r lcate 0.1 sq m samplesat a shallow 2.0 ! Pd t gaeti y Santaa MonicaBay, Ca I Ifarnia; and2! Verticail distribution patterns;deter- rnfned through the analysisof benthiccore sampfes. 4 cmI n arne di t er taken s a ons, each represent lag a di f ferent sed1 mentt ype f I gure2 and Tab I ee . I! . Six x core samples from each station were sectioned at de th tervals ai 2, 5 10 200, and 30 cm, and the organismspresent In eachof the sub-sampleswere identified and enumerated.The e adat a on th e number of spe- cles an and indlvlduaisin v ua s from fr eachsample were combined ta determineth b of re I i e num ers p 'cate samplesand the depth of penetration requ uired re to o oobt a n species accountln g percent for over 90 of the Individuals at each station. Addltlon- al analyseswere made to predict semi-quantitativelyy ecom the combined ne e ffec t sof pressure waves, leakaea age, e and and surface disturbanceon the organismssampled Word et al. 1976!.

Onthe basisof thesecollections, certain crit'erie wareformulat ormu a e d andd used for selectfn ng th e most effective grab sampler, The more efficient devices are characterized by the fal lawing features: Consistent sampling of the samesirrface area Consistentsampling below the depthwhere the majorityof species and spec1rnens occur 3. Minimumsurface disturbancecaused by pressurewaves 4. Ml»imumdisturbance due to leakage

Horizontal Distribution Patterns

Horizontal distrfbutiorr patterns of marinne b en thl c inver. ' t ebrates have been studiedat manystations in a variety of manners Greene, 1975; Smilth and Greene,1976! Boesch, 19731 Cassle and Michael 1968 Fa r 19 method of me o o describing the biota at a benthic station Iss oto colin co nc t . refrlicate Ii samp les on at a conf inedarea until the asymptoticpoint of speciesacqulsltlan has beenreached. It has also beensuggested that this oint b indicate e he the numbernu of repficates required to adequatelydescribe a benthic station Jones, 1961!. fr"waver, How the numbersof species prepulationlevel . of thevarfou- species collected - ona a»ant yses'I station, on the i»» h!i I ion tn the analysf; of fire speciesaequi sf I inn curve

46 tfe found that the asymptotic point of the speciesacquisi- tion curve had been reached Ot OI after 10 replicate samples had ! 3 SP been taken at the shallow, sandy St/cc6551'! = 6: P IL 4 7 tc9 station. This indicated that Ot SAI,IPLIIS '0CIO I/I IO en IO replicate samples were not wtt c3 79 ID IO Ot adequatefor capturing all those QEOt +- 4 +. SI speciesthat could occur at this station Figure 3 a!. However. 60 I/I C7 O vt In 0 an additional anal ys'Is performed 5 on these salne sample~ showed L v7 that those new species added by L Itt I- 43 tD I each add It iona I replicate did C e Gt Q L Q Q Q X Q +2 npt OCCOuntfar a large prOpor- 33 2 tlon of the lttdiv'Iduals. For 0 example, the average of zo second samples contained addi- 19 tional species account Ing for IO 0 only 10 percent' of the 0 L IO 'Indlv'Iduals Figure 3 b>, 1 2 3 4 5 6 7 6 9 IO 0 C 0 C V Q I/I I 41 86PI.ICA=.6 CL 0 IO Ol V IOI I/I 0 Irt '0 0 Q +-0 mQ Q Fven sophisticated analytical Q V C L 7 Cl f techniques eg. Smith and L lit Greene, 19761, In which species 700 Ot V 0 >I 0 W Q 0Irt I/I Q ct Q E L or stations are clustered to- L IO IO L ~ IZs- m 47 90 C7 Q 67 Ct I/7 gether basedupon their rela- '- u/ ol '0 tive simliaritiles in distr Ibu- Il. 2 0 an c s7v V 4 99 O. 0 C Q tion are most sensitive to E E 00 L IO 0 8 Q ltt L E E C I Gt E c Q those species that accourtt for 29 I/I 0 ~ L Q-IO 0. CTIC CQ +-Q2 a I 90 to 95 percent of the total +- vt I g + lo u/ z et p 0 IOI/7 IO Q nutober of individuals sampled. o C C w ~ CIO v- ~ Q 0 'L 0 0 L O. Since the second sample yields sp v- In V C7Ltt C7 OILII I/I Q 0 E 'N s7 tn v species which account for t t 0 I 4- In tc tt. 40 C CI 0% 0 I/s 5 3 3 percentof the fauna, it would 0 0 appear that for most purposes, I/I 30 L IV a single sample or at most two. W 47 Q V CLE will capture the majority of Ill 20 the fauna occurring at this 0 0 ID to n/ 0IO type of station. It should be 10 IO 0 e/ tn '' Ct emphasIzedthat different con- I- r- 0 I/7 Ot clusions regarding the number 1 2 ~ 6 6 3 9 9 10 of repllcates needed can be 7IBPLICATES L 2 derived from the type of CI N analysis conducted, but it is 0 Figure 3, Species acquisition a! and pere tn 0 tnIn in 0In In Ct our opinIon that useful descrip- I- tt7V tt7In ftl tNIIn tn numerical acquisition bt cu/vet t ve information fs obtained with successive replication nf sampll sIngle 0.1 sq m benthic samples for at lease soltne substrate types C 0 Ot /O Vertical Distribution Patterns IO Q I- I/I 1he 3 stations sampledto study the vertical stratification of organisms deptttswith In the sedI mentvaried In sedimenttypes and In sumpI I ng denttt, from 12. t to 260 mi. In general, we foundthat althouqhorganisms burrowed 48 49 moredeep I y within the f incr sediments,about 9O percent n o of th e species and individuals were present r in the upper IO cmof sedlment at el I st t I sampled

, a a s a ons

Physical Functioningal GrabSamplers

Certainmechanicai attributes of grabsamplers affect ec th e I<- ability to cap- 'g sms, Someof these are: pressurewaves t d b DD durin crea e y he samP ler g its descent, leakageof sodimenta n d an I maI s nom f oiieningS In the device, and disturbanceof the sampleance it ls BD Haime, McIntyre 19fl ! . p e ance s contained within the sampler 70 uantification of the effects of the fi icu It, , We used information ono eseIhe reiatilve mechanical variables ls extremely dif-

Pentop ra oie aou.ied Fas F4le Good, Far, Good, Comparisonof Major Categoriesof Beiithic Samplers 2 23 I Gooif, Poor, 2 I I ftt h ,agaI eucced 3 Asdescribed In previoussections, the dl I fererilsampi ing devices obtained G cod. Fair. pair. G and, iocapt it netanlol ICON 63-66'4 Poar Pons Good di Iferentf elativeabundances of organisms based upon their pencilation 2 2IOON I gotf 20.100nr 48ICON ae e c .tai I cgi ~ 10014 within the sedimentand also uponthe surface area sampled. 'tie 4 area~ tt: Ihi1d iiictct nayn vary ae much ac 50+.

52 53 Comparisonsof ihe 3 majorcategories of berithlc samplers benthic grab de- , n intertidal vices, deeperpenetratilng birrrowers or boxcoring devices,und the shallow A.D. Michael. 1968, Fauna and sediments of an inte penetrating epibenthic sleds! will be discussedin this section, mud-flati 'A multivariate analysis. . xp. Benthicgrab samplers, eg. thechain-rigged Van Veen! efficiently sample Fager E.W. i957, DetermI nation on and analysis of recurre gro p ' the infaunalorganisms to a depthof approximately10 cm in mostsediment Ecology 38:586-595. types. Thesesamplers are the generalist,that Is theycan capture the ma- 1975. Multivariate analysis of benthic eco-sy.'iem; jorfty of differentanimals livilng on and in thesediments but they cannot ite EPA T sk R t G t I 80II' 2! 85 be usedto selectively samplethe deeperdwelling organisms or thosethat a inar ne wastewater discharge site. live on the uppermost surface of the sediment, A,D. Mclnt re. 197 . Methods foi the study of marine Toobtain Information on oiganisms living deeperin thesediment a different benthos. IBP Handbook No, 16, 7 Mary e one o typeof samplingtool shouldbe used such as the anchordi edge oi- the box I, A uanf tatlve evaluation of iihe benthic launu iif corer. Thebox corer is drivendeeply within the sedimentas a result of its weighand inomentum onbeing lowered to the bottom.These samplers are Point Richmond, California. Universi y o veryeffective at capturingorganisms to depthsof about40 cm. Theanchor 67!:2I9-320. dredgesamplers are drfvendeep yw!thin the sedimentas a result of the forceof the vesselpulling against a leverwhich forces the dredgizInto the ries S. Greene, 1976, Biological communitir n niiar bottom,also to depthsof about40 cm. However,both of thesesamplers are submarine outfall. Journal Wat, Poll. on , e typIcaltysmal In sampledsurface area and as a resulttend to misssome ot Aug , 1976 1894-1912. the moremobile and sparsely distributed invertebrates. wl ln and A.J. Mearns. 1976. A comparulive f ield d In Souttiern Ca! i fornie Theepibenthic sleds collect material froma minimaldepth aboutI cm! of field study of benthic sain p lin' 9 devices use penetrationover a widearea of sampling,and therefore are integrative benthic surveys. EPA Task R epo ort EPA Gran R801152. samplers.These devfces wlii collect moresurface dwelling animals and those device mobileInvertebrates such as themlcrocrustacea that ereable to escapethe al corn arison of grab sampling device ., motecommonly used benthic samplers because they are towedover larger areas Coastal Water ResearchProject, Annual Report andare more lilkely to encounterand capture these animals. In the final analysis, wehave to considerwhat we want to learn fromour samp!Ing.After lookingat the stomachcontents of the fisii speciesof interest,we can get an idea of thetypos of species,the sIze categories of the food,and whether it Is stationaryinfauna, or a inovableepifauna. If a comprehensiveinvestlgution of numerousfish Is required,thon a moregener- alizedapproach is necessary,and the useof a VanVeen sampler is advisable. If, on the other hand,the Investigationcenters around species of fish that feedprimarily on epifauna or that feedon deepburrow I ng formsof i nverte- brates,then an eplbenthic sled or deep-buirowlngsampler might be preferable. ln this paperwe have presented information on benthic sampling devices, the organismsthey collect, andhow these samplers can be usedto assist 'Invest- igations Into the feedingtiabits of filsh. It Is hopedthat further research andcollaboi ation betweenfishery andinvertebrate b Ologfstswill broaden our understandingof the useof thesefools in investigatingfaunal re ationshlps in the marine environment.

EITERATIJRECITED Doesch,D.f. 1973. Classificationand community structure iif ma:rokenfhos in iiamptonRoads area, Vli giriia, MarineBiology 21, 226-44, used a baited freo-vehicle automatic cine camera rvey demersal organfsms and to observe tho behavior of thn>se organisms willh respect to the otter trawl Allen 1975>. ELOMETHODS FORSAMPLING DEMERSAL FfSH POPULATIONSANOOBSERVING THEIRBEHAVIOR Relative Selectivity of Methods

James Alien We have conducted quantitatIve surveys of demersal organisms In Santa Ilonica "outhern Cal lforn Bay uslnq 4 methods otter trawl, rod-and-reel, set-iino, and phofograph; EI Segundoeg undo, astal WaterResearch project taken by divers; Allen 1975!. Ih lrty-one species of fishes were ohser> ~ I in photographs of the discharge pipes in Saf>ta Monica Bay

Rod nnd reel sampling on soft-bottoms yie'Ided 15 species, and setline sa>nplin>7yield- Whilepopulations of shallow wafer or anlsms ed ll species. A total of 23 species were taken by both hank-and-line rnefh- equ pment, deepwaterog demersal nb an o e yby ods, with only 4 species In commof>between the 2 methods; spiny dogfish g nerally be sammp I e d y b remotemethods. A numbrsaI rand bef>thicor Dani sms must Squc Zue cu'.eftfthiaa!, sableflsh AnopZapo»fafimbria!, white croaker Geuyu>k. be usedto obtain I nt erma tl on on the o uiatl umer of sampllnqmethods can mue Zineatua!, and Pacific sanddab Cit!>ariehthya aovdidua!. In conifasl, organisms. Thee ab'a jec t Iveof this paperp pIs to ons descr andibe behaviorth of demersai 87 species have taken In Santa Monica Bay by otter trawl surveys conducied tivity of thesemethods s annd t od escrlbe b the t e cr e e relative sel ec- by the Coastal Water Project. Photographic and hook-and-line methods yield- proprlate for obt a In ng different t esb ypes of o of methadsthat are ap- ed only 2 species that' were not taken by otter tra~l In this area: Pacific Informatian n on o th ese organisms. yp population and behavioral hagfish Eptat> etue etouti!, taken by setllne, and an unidentified ronquil >fat>>Z>u>MZZaap.! observed In the photographs. Both species have been MethodsForsampl lng the lar ger or anisms I ivl taken by otter trawl elsewhere. More species were taken per station by organ> sms> vng nearthu boitom fa I I Into + egor es--capture methods and obset I methodsresult . u in n thehe organismar anism being brought etvatlanalto the surface fnethods. le Capture otter traw I < 10, 4t 0, 4! than by rod and ree I 3. 6 - 0, 5! and set I ne whereasobservational methods allow the or anism ' cad or alive, .3 0.7! methods, although time spent on the station var led considerably ur e n ts natural environment. otter trawl, 10 minutes; rod-and-reel, 4 hours; and setllne, I hour!, Capturemethods used by the Co,>stal Water Resoar h Setiines were most etfectlve at sampling wide-rangif>g species that forage on the bottom; the set inc did not sample rockflsh populations. Rad-and- m- ft-> headropeand have a 1.25cm-.5 w u.o In> cad-end a r reel fishing into schools located by sonar was effective at catchlnq spec ies n; esetrawl s areqenera1 I ytawed at 4.6kmv'hr . 5 kn>a such as rockfi shes that range higher off the bat lorn and are generally cia>np- ms e a . 1976!. Wehave used 2 h ed. Otter trawls were most effective at sampling smal'I bottom fishes such fo sample demersaI soft-bottso - o> ~ f I shes Al I enet al. '1975!;>ook-and-line ! methods as flatfish' sculplns, and small r ockf Ishes. IDD-hookset Inc acrosscross th he bait»mb it to catch the s e I We laild a range of the trawl th t I h p cies w thir> the vertical Although we caught a proportionate! y greater number of large f I shes with fish located b a m g t avoidthe net and! wefished schools of y sonar in the general vlcinit of the hook-and-I lne methods than with the atter trawl, hook-and-1 ine catches rod and reeil too collco ec t speciesthat either dwelly o the In trow stations with usually fell within the size ranges sampled by otter trawl. The hook-and- the vertical rangeo fe th trawl or are hlghl clum edn the water column above Ilne catches showed that more large bottom-feeding fish mostly sp'Iny dog- be frequentlymissed by the trawl, y mpe and therefo> e might tlsh! occurred ln shallow water than was indicated by olier trawling. We have also us used a numberof observationalmetf>o>!s Incl Photographic sampling was effective at showing the species particularly ve s an remoteobservat irns frome o free- I 9 os invertebrates that cannot be taken by hook-and-line! found on hard substrale and television cacanreras. .. 0'Divers have hot ree-vehilc e cine cameras areas such as outfall pipes! that cannot be trawled, This method was also out ail p I espes in Santal ion i ca Ray to p100 ographedm usin SCL! marinee >A organisms! around very useful fn showing where the organisms are living--information of this water and two-mann » »bme.rsibies me.rsiblesin deep water Allenq .i, ei equal. prncnt1976!, in We she have I low sort is almost always lost by capture sampling techniques. The disadvant- aqeS of photographic Samplinq Incl>fde the dlfflcul y ln making aCCurale identifications of organisms observed and In getting .Ize estilmates on sr>me species.

>6

57 Videotapes of otter trawls In action suggestedthat manyof the fishes and invertebIates encountered escape the nets. Largerer fish is s pecles such as the PacI f I cI ange s hark Squatinacalifornica! havebeen observed to swimiiito OI VI the net, becomeentangled and later swimout before the nel .. re r i vi I . a I c les often swimup andover the net. Sisaller bal!om spLLies cOl IO Vl L such as speckledsanddabs, Cithorichthys stigmaeus!swim w irn,el I igi hli I yof o f l lie ie L e CD bottomIn front of the net, trying ta outswimIt, furbots Pleuroniohth!fs OI E +. CD E CO0 rv sp.!,p., which ' are oftenft buri b ' e, ed jumpVer t ICalI yI rOmthe botlnm when I Illi IIL c- L0 l Q onl to f el I with'In It. Sea pens and tube-dwel I ing polychaeles, W C- vC0. approaches, on y o a wi n O which have a certain d gree of attachment to the botlom, are not well we sam amp led. ICC m I Oi t d t dl f f .rent behavioral and ecoiaqical iii formation Lc Sampling me ho s or 0 Different sampling meII io ds leld y e di f ferelit types of behavlor a I and ecialogical I I d I th presence of large predators in lie area arid the Cjl L Information nc u ng e I/I + 0 die I activity patterns, foraging behavior, and food preferericeo i r reri 0 I IO ID 0 species. ce V> rv rtl E o Large preredators--large ors-- a fishes that prey uponsmall speciesnormally caught in ai small otter trawls are not frequently captured In thesee trawls. . p In arl, aIO c this is due to their ability to outswimthe net at the speedstawed, as men- m d b e. In addition, however,this Is alsa due to the low densities IO of their populations. Largebottom-foraging species genera r II y q re u1re a Vl Z Vl m c CD L. larger foraginq space t o 0 bl'ain enough large food liems! than da smaller Vi IO OC d th ur in low densities. Information on the presence oof Oi 17 m o species and us occur in ow Ol 0 to cD 0 thesespecies In an arearan beobtained by attract ng em o a ai D p resenue o Iaige I P ar Ific sleeper sharks Somniosuspacificus! In deep«alar Oiv- t k own until liiey were phataqraphedby Lai O CO ln southern California was no nown un 0 ai free-vehiclecameras lsaacs and Srhwarzlase 1975!. Wehave found hiqher c 0 densities of spiny d og fish is Squa uaLus us aacnzithias!, swell shark CephaLoscyLLium 0 d areas O Vl verltriosumi,i and b sa I ef i i ssh AziopLoporlvafimbria! in I requentI y t rawle areas VI than was indicated' f d b y the trawls. Set-!inesalso indicatedhigher ensi 4I o of splaydogf I shon the shelf t!lan wasindicated by trawling. L. Oi CD c 0 L Oi OC Vl VI I I- f!ieL activity--d! fferences In dial act ivt ty amomong f I shes in the f ie Id lieve IL +- L ID 0 Vl ID + Ccl beenobserved by divers usingSCUBA equipment in shallowwater Starckand V- Lo 1965 1968, 1974!I but dlel activity differences among IO V- deeeep ~sterwa e species havebeen less frequently observed. Ba e ren-vn iir 0 cameras 'left on the bottom for 24 hours g hour or hourh r! have ave shown s diel differences in several species SCCWPP L c- e 19!. At a 23-mstation senorita OoryJ'uLiscaLifornica!, y 9 IV+. c C hoterus v ichoLsi!and blue rockf I sh Ssbastesmystinus! were act ive IO 0 er rackfish Ol ur In the da «hi le treef I sh Sebastss sezriceps!, copper +. +. L o IO IO 0 Se bas tss Bs cnurilfus!and swell shar k CephaloscyLLium Verctrioaum! werc ac I Ive IO+. VI VI L I ht. Television camerasdropped to fhe bottom at nl g ht have shown Vl o E C L. only at n g . e IO CI Vi 0 CCI raff Ish HydroLaguscolLiei! activelyforaging and individualin p' ink seaperch +. Oi 0 m +. oB Q IOCO ZaLBIIIbiusr osaceus! resting on the bottom. Trawlstawed on !he samesta- al + LIO E c crl vi In the da and at night haveshown few majoI catch difference IO e Ol tlons during the ay an a nig I r iminate bet ween spec ies tiia I ai e vi+1 presumablybecause the trawl doesnot d scr minae e w oIO IO Ol or Sl i htl burled in Ihe IO ac tive ive or inactive nac generally seekingrefuge on or 'q y IO 0 Ee lo+- bottom!. Major differences Include increasedab u n dances . ~ ofp s otted I.ii k-lei m 0 CLg I Vl

58 59 Cfri arrrtcrytori!, ratf i sh !iyjrorayus c'ofliei!, and nor ihern lampf ish Steno- rac!riusleuoopsarrrs! atnight. Cask-eels general ly burrow lrria the sediment f th g ni sms ln the l r natura I envl ronmen drrrilngtheday and are Ihus unavailable lotrawl", whereas theother species samplin ng ggives ve more infarmatlon on the behavior of the species ln their nat- probablymove Into the trawl areas from cio per water at nlgirl. ural env I ronment , u b t Identifications e can be less accurate, and fewer meusur- able data are gathered. A combination of sampling metirodsh thon then wouldwuu r y Ir'ld Forargingbefrauior~-absorvot lorraI orrci hook-arrd-I I noteclrni qrros irave shown d f-I the most behavioral and ecological Information on deepwalar demur' al fi erencesIn foraging behavior arrroncg demersol fish . 5 I I . I 'k, fishi sh,sab ief ish, treef i oh, copper r'ockf i sir, and Pac I icf sleepershark have beenobserved crrr Is Ing above thebottom searching forfood Items onthe bot- blterature Cited tomin bolted camera f ims,i whi le Ca! i for nia scarp ionfish Sooi r t tt ! aveoen observed to ambush prey fr om I hebottom and shor tbel rFaenaI yrocrcf rfuI sh a a Allen,Al , M,J, 1975. Alternative methods for assessing fish populatiorrs, Sebastesjorrfcuri! tnactively pursue small nektonic organisms Inthe wafer Annual Report for the Year Ended 30 June 1975. Southern California column,I argo sebi efI shwI II b le i Intoa Isr go, dead bait f sI hand sp ln Coastal Water Research Project, p. 95-98, theirbodies untI Ia chark of flesh ls lornoff I saacsI and Schwarz lose19751 whilePacific hagfiSh Sptatretrus stouti! wiii slide a knotd rwn their bod- Alien, M.J., J.I3. Isaacs, and R.M. Voglin. 'I975, Hook-and-Iino survey af ies,farcing s!Ime onto the bait and thus protecting thefOOd Item rom Com- demersal fishes In Santo Monica Bay. TM 222. Southern Cailfarnir peItors such as sableflsh. Video tapes have shown spotted cusk-eels cruis- Coastal Water Research Project, 23 p. ngslowly above the bottom, dragging tlreir barbel s along the bat fr>rrr. The twohaok-and-I I nemel irods deimanstrated a dI ferencef in foraging behavior ~ M,J. H, Pecorel I I and J. Word. 1976. Mar ine arr!onl sm- a;;ncirrir rl amongthespecies taken; setl lne catches were dominated bywide-ranging bottom with outfall pipes In Santa Monica Bay, California J, Water Poilu t. foragerswhile rod-and-reelcatches were domilnated bywater-colum f I Control Fed. 48:1881-1893. rockroc ffishes I such as bocacc lo cSebaetee paueiepirrie! andverml I ionumn ror-kf1sh crag ng Sebaeteerrrirriatue!. Hobson, E.S. '1965. Diurnal-nocturnal ocilvity of some Inshore fishes in the Gulf of California. Copela 1965:291-302. Foodprefererraee--by usingdilfferen l types of balt,some ilndlcalion of food preferencescanbe determined. WhaleDover sole A!icroatomue P uif' ! d Hobson, E.S. '1968. Predatory behavior of some shore fishes In the Gulf of Cail fornia, U,S. Fish Wl idl. Serv. Res. Rep. 73, 92 p. stripotalas ai lnI therockfish balled Sebaeteecomers studyaazieotar! was consumedwas consumed. Inone-fIflh Presthe bl tline Ir that I on th e rrockflsh make the species less desirable uto . r d resumaI Ih ly DoI lie spines Hobson, E.S. 1974. Feeding relationships of teleostean fishes on coral whwhichch has h no sharp spines. Sp I ny dogf I sh, sab eI preef I sh, and a orsPac If onI c hagfDover I solsh were e, reefs In Kana, Hawaii, Filsh, Bull., U.S, 72r915-1031. e onlyspecies observed eating the balt. Capture methods, ofcourse, gen- erally providethe best food habit information because thestomach contents Isaacs, J..D. . an d R.A. . . S c hwartz war lose. 1975. Active anima ls of the deep-seo of the fishes taken can be e>

Conclusions Mearns, A.J., M.J. Allen, L.S. Word, J.Q. Word, C.S. Green, M,J. Sherwood, and !3. Myers. f976. quantitative responses of demersal fish and Ofthe 3 generalmethods Iotter trawl, haok-and-line, andobservational tech- ben thl c nver il t ebrate corrinunlties to coastal municipal wastewater nlquesl,otter trawls are probably thebest method ofsampling smallbottom discharges. Final Report, EPA Grant R801152, Vol.I. II, 67 p,, , Vol. o fisheson soft-bottom areas--the trawls yield the greatest number of species 179 p. andnumbers of individuals fromwhilch additional measurements andanalyses canbo made, Smalf atter trawls probably donot efficiently sample large, Shutts ~ R. 1973. Cinematography on the ocean f loor. AAm, . CiCinemato e g. . 54:462. fast-swirtrningspeciesor species that burrow Inthe sediment. i.arge ~pauses foundaver soft-bottoms areoften more effectively taken by hook-and-line Southern California a orn a Coastal Water Research Project. 1973a. The ecology uf techniques.Ofthese, setlines more effectively sample larg 'd- the Southern California Bight: Implications for water qua I it y marrore- a omeeders, which may escape the net; fishing by rod and e,reel wi e-rangIn schools ng ment. TR 104. Southern California Coastal Water Research Project, 531 p. locatedbysonar is a moreeffective way to catch the highly clumped rock- is esthat may be missed bychance In a trawl.Photographic andhook-end- Southern California Coastai Water Research Project. 1973b. IIaited camera Iinemethods are both effective at samplilngrocky bottom areas. observations of demersal fish. TM 207, Southern California Coastal Water Research Project, '10 p, Samplinqmethods suchas otter tr jwlor hook-and-I inef Ishlng allaw accurate irlentific:ationof specimens andmeasurement ofsize, ercomlnat Iorrror diseases, andanalysis of stomachcontents, although they give iiittle informationasto

60 61 SouthernCalifornia Coastal Water Research Project. 1974. Db" a baited a e moviecamera. Annual Report for theyear Ended 30servatlons J 197 with SouthemCal i fornla CoastaI WAter Research Project, p.n e 45-52. une 4. Starck,W.A., II., andW.P. Davis. 1966, Niighf habits of filshesof AlligatorReef, Florida. Ichthyol. Aquarium J. 38:313-356.

SAMPLINGINTERTIDAL SALT MARSHMACROUENIFIOS ContributionNo. 80'from the Southern Callfornii n a Co as t aI atel-W ResearchProject.

James E, Smith Washington Cooperative fishery I

My thesis work Is the analysis of the convnunity ecology of the benthic- in- vertebrates of the salt marsh-mud let system at the mouth of the Ska lit River In Puoet Sound, Washington. The river delta Forms Skagit Day, a 25-Ir rx- panse of sand and mudfiats ringed with salt marshes. Most of the perimrtor of the bay Is diked. Numerous smail tidal streams cut deeply through the emergent marsh, spreading out and beccmlng shallow on the unvegetated flats. During the spring and summer, the tide streams contain large numbers of prrd- atory fish, particularly starry flounders PLntto>rthya ateLLotua!, slnghorn sculpins Leptocattue arrrrrztue!, threespine sticklebacks grzstemsteus aouLeatus!, and the juveniles of chum Oncorhyrrchus kata!, chinook r!. tshasybeo>rzz!, and pink . gorfrrraofra! salmon, As part of my study, I arr attempting to determine the Impact of juvenile salmonid predation on the populations of the benthic Intertidal Invertebrates,

ln planning the benthic sampling phase of my study, I had to consider .ix major problems commonto any soft-bottom sampling program; I! core depth, > screen size, > size of plot or lenqlh of transrct!, ! Froquvnrr sampling, ! core area, and > number of samples per plot or transect. wanted to select a sampling procedure which would allow me to sample as rrrany of the prey species as possible and to provide enough individuals per sarrrpie to make accurate population estimates and reasonably powerful statistical tests. I am reporting here the processes by which I chose my techniques for benthos sampling,

Core Depth

took 10 cores, separating them Into three depth intervals: 0-4 cm, 4-8 cm, and below 8 cm, The total depth of each core was 15 cm. The results are shown In Table I,

63 62 TableI Vertical distributionof benthicInvertebrates. Data frcm 10 cores were pooled. I had !ittie time to consider It In depth. In the course of other preiiimlnary wor k ,I a h d t ak e n several sets of samples aver variously sized areas. Since sampI est a kenen ovover an area of 3 to 4 square meters had shown approxroxiinatel nia e y the same spec I esIt compos lan as samples taken over severa 1 hundred square me!ers, 0- 4cm I assumedthat the dominant patch size was probably less than several nialers. 4 - 9 cm Below 8 cm I chose to locate samples along a 15-meter 0 feet! line ~ since tiil wa...a Total number 966 convenient length along which ta sample. It was small enoughta sample quick- ' 41 26 'Iy> but large enoughto prevent superimposing successive sampleson previous Percent 93.5 2.5 saimpi e I ocat I ans.

Sinceover 974 of 'the animals occurred abave 8 cm, I decidedto sample only frequency of Sampling to that depth. To det ermI ne popu I at'I n parameters such as reproductive times, seasonal trends ln abundance, and growth over time, sampl'Ingmust be daric at close Inierv*ls Screen S'Ize relative ta the life span ot the Individual arqanlsms, Since mast af the in- vertebrates I am samPIIng are sma'll and short-lived an the order of a yiarl ~ Scr.eensize Is a trade-offbetween efficient sampling and efficient labora- decided to sample monthly, torytreatment of thesamples. 1 wantedto sample asmany of thesmaller species,including Juveniles, as passible and yet pass enough sediment and detritusta expeditesort i ng. I tried severalmesh sizes rang in from4. 0 Core Area a 0. 9 rnmand found that the smallest mesh sizes, though very efficient at As a result of the extremely dense populations of macrofaunaon the rnuijflats, retainingmast juveniles. passed very little sediment.I decided to choose 2 thatmesh size which would sample a high prapartlon of the Juveniles of two I found that laboratoi-y processing of standard 0.25-m samples was too slow. speciesof amphipods,Anzang>zrrzrrrzrue nnnfervznnlue andCnrnphlurrr eulmorrie, whichoccurred frequently in stomachcontents of Juvenilesaimanld fish from I d I t I t bing which took ca~as of 38. 5 cm, but w thI the, creen the lowerSnohomilsh River. Theresults af successivescreen'ines 1 fo size I wished to use .297 mm!, this stl I I sarnpled so many animaIs triatri I it i sarrps arr es con ain Ing these amph Ipods thrauuh three mesh sizes are shownln was impr'actlcaI to take morethan 2 cores per station, In general, uri less Table 2, nd rec I s lan are sacr I f Iced, I f i s lief I er to deer ease sampin: i ze and Increase the number of samples, This provides a e er Table2. Efficienciesof threemesh sizes in retainingthe ariphipads variance of the population. Cnrnphr'rxmerzfurrn>rze and7I>rzeng>zr>rnnrue cnzrfervf r nlue. Dataf rom In order to just ilfy my choice of a smaller i arer I wished fa use fourcores were pooled. Both adu its andjuveni les werepresent. plastic tubing!, I took a series of 18 samples in which I nested sinali cires st oi the large cores with Retained C. arzlmn>ri e u>n>ifpr'l>1.aolrrs inside the large cores. Comparingthe species by 0.99 mm that of the smail cores, I found that every peel a sampled by the large :ares 0.297 mm 0.175 mm 0,99 rrmi 0.297 irim 0,175 mm was also sampled by tlie small cores. Apparently no species was sa rare that Tata I the small cores missed it. Also, no species was better able to escape 'Idiom number 136 100 0 142 56 0 the small cores. Percent 57.6 42. 4 0.0 71,7 28. 4 0.0 Edqesof corers passingthrough substrate trigger avoidanceresponses in many d t nd ush down animals that should have been included in the care. Since the ratio of circumferenca to area Is larger or a sma core The0.197 mm meSh refairied l00$ of the amphlpadS.Since li pa' edmuch Of n for a lar e one, this edge effect causes smaller cares to uridernstimate the Substrate, I chOse thi . SI ve, invertebrate abundances. I found that, for the mas a un an sampled,the o posite wastrue; the large cores underestimatedabundaiii:e:. I elleve that this was due to the greater difficulty in sort'Ing the m >luriai Size at Plot f romthe e a lar g e COres. Apparently any edge effect waSSmail cOmparedto thiS e ffec . t. . ma S II e r samples often cause an increase In variance. w ln orderto decidethe scale over which samples are ta bc taken,same knowl- found f h* f f oi. . th e ma 5 mastma abundant spec .' i e, , ' the var i ancxs r a lcu I ate d fram the edgeof thescale of patchinessis required. This ils a cr>mplexiuestian and sriiaiI cores were never significantly graarer f hah fho;e i a icui e iim> large cores M ase SeS Raiikl ike Te,i for !ISP>rS laii-Me'lian Ilnknown ar rlrw 1»1, cc = .05!.

64 Consideringtheabove results, I decided the5.07-cm core was appro r late for my sampI 1ng pr ogram. p pr a e or 5E ;IIFNCF1 Numberof Samplesper Plot or Transect To

Corophir

67

66 FEEDINGHABITS ANO SFI ECTI V fTYOF PLEURONECTIDS ON THE OREGON SHELF: A SUMMARYOF RESEARCHIN PROGRESS

Wendy L. Gabriel School of Oceanography,Oregon State University Cervaflls, CR Thepurpose of this on-goinqstudy ls to investigatefeeding habits of flsheS acceciatedwith either Doveror Eng ish sole. In partfcular, 3 aspectsaf feeding habits in each fish communityare being consildered:I! vertica! dis- tribution of macrofnfaunawilhin the sediment as sampledwith a boxcorer!, DISCUSSION; SESSION2; SAMPLING OF BENTHIC PREDATORS ANOPREY: andthese organiSms' availability as fish food2! diel periodicity of HOWDO DIFFERENTSAMPLERS AND SAMPLINGTECHNIOUES p'euronectldfeeding, and 3! seleciivity of foodspecies and sizes by ALTEROUR IMPRESSIONS OF' THE BENTHOS? pleuronectids.

The sampling plan was designed to determine what potential food "choices" Steve Obrebskf mentioned that while the benthic sampler used Is Important, were available to demersa fish. What invertebrates does a fish actually the method by which the sample Is processed is just as important. For "seew In fts environment? To assess the benthic macrofauna, we used a 0. I ~ example sieving a fresh samplemight allow the slimy, smaller organisms Bournebax corer and a 0.2 5m2 Hessler-Sandia box corer, To ample macro- to slip thraugh the mesh while preserved animals are stiffer and less epifauna, we used an eplb enthlc sled. To col lect f l shee frcm the samearea, I lkel y to pass t" rough He further mentioned that a sieve size of 0.5 nvn we used a 3m beam trawl. may nat have a great eff Iclency for recovering numbersof organisms.

Two stations were Intensively sampled. SG-27 4 26.0'N 124'14.3'W C2m J Im Alen I presented presen a brief overvie~ of the SouthernCal I farnla Coastal deep, sandbottom!, an area of high catchesof Pacific sanddaband English WaterResearch Project SCCWRP!.The group wasestab I 'ishedto study the e sole; and SG-294 05.0'N, 12435.0'W, 112m deep,silty sandbottom!, an ecologyof the SouthernCalifornia Bight andthe sourcesand effects area whereDover sole is abundant. Samples,taken day and nIght, Included of pollutants In the area. Thefunding comes by wayof the southern 18 beamtrawls, 4 eplbenthlc sled hauls, and 20.0.1 m2 box cores at each California counties. station. R dl SCCWRP'suse of the underwatertowed camera system, Bob Feller For studies of vertical distrlbutfon of wacroinfauna, cores were sectioned at cgerk d If ng th grouphad ever reversedthe direction of the camerasso t a I-cn Intervafs for the f irst 'IOcm, ~ ">2-cm Interval s for the next IO cm and n aid 4 cm Intervals for the remainder of the core. Each section was then washed it recorded the fish's behavior whenapproached by the net. Allen sa througha I-nvnsieve screen, If the numberof sections werereduced, that Insteadof that they hadattached it to the bridle to observefish artifiacts, contamination, and sample loss would probably decrease. behavior. He agreedthat somefish are able to escapethe net. Usually'alf fishes froma trawl werepreserved, Ta Insure rapid pre- BruceHlliaby wonderediif anyof the attendeesused the flotation method servation of stomachcontents, formaldehydesolution was injected Into the for Initial sorting of benthic samples. Jfm Smith replied that In hfs body cavity with a size 16 hypodermicneedle. Whole fish were then stored case the substrate wastoo full at organlcs sa that by the time one had In formaidehyde solut!on. the proper concentrationof sugar or other materials! everythin ng ln n e the tray floated. JackWord added thaf flotatlon or elutriation methodsare Problemsar fee out of the scafe of the sampI Ing program. Thearea bound- It ble for molluscs. Hlilaby then wonderedif a combinationof ed by trawl tracks and box cores wassmal I .5 km2for SG-27;'l4.8 km2for unsu a 't too SG-29!, and each station was occupied only 30 hours. Patchiness effects flotatian and hand-picking might work. Word added that he Isn oo maybe present, since areas of box coring and beamtrawling overlappedbut crazyabout f Iotatlon techniques.One technique that Is comingInto wider did not coincide. use Is the elutrlator or "bubbler." Alr and water are jetted up e column conte ning the sample,forcing the lighter animalsover the top of the columnonto a collecting screen. Whl'leth'Is methodIs adaptableto sand andgravel substrates,It doesnot workfor vegetation. Noneof the attendees had any goad system for sorting animals from vegetative materfal. TaivoLaevastu suqgested that benthicstudfes should be examined to see lf

68 69 researchers could reduce the spec1f lefty of Invertebrate i dentn caif icatl ans. their guts. F'Inally, he measuredthe overlap In particle size dlslribu- He t s ated that working on benthic samples Is very tfme consumlnonsum ng an d we shoulds ou examinethe goals of our projects to see lf they can be achfeved f ion between species and at the sametime determIned, by nearest neighbor- with less time spent, This time couldthen be devotedto other things. statistlcal technique, the differences in spatial configuration, fhe Jlm Smithwas asked how he avoideddisturbing the area In which he takes general result wasthat those species«1th the highest diet overlap erc core samples. He replied that he trfes to prevent taking cores within least likely to be nearest nefghbors, For example, two spfonfd palyzf/eefus, one largo and one smail, occur 'In similar areas. When they do occur near 5 cmof a previous core. DIsturbanceof the samplingarea Is dfffi cu lt t o avo1dsince one is alwayskicking up sandand mud, whir:h are then each other, the larger one whips with its paips and tears the palps fram carried by currents to other parts of the sampiIng area. the smaller one. Small spionlds, when close to large spionids, mnvr: away and therefore are nat nearest neighbors. Referringto anearlier suggestfonof usingexclusion cages, Obrebskl Joseph Ourkln mentioned that he had observed Pacific sanddabsfeeding on askedlf any of the benthic organilsmswere mobile. Smithm pep Il e.d a th t hee e beli eved v some ot the tube-dwelling amphlpodsand polychaetesmoved fish in the area of the mouth of the Columbia River. Allen agreed lb at he had observed similar behavior In Calffornla bui Gabriel had not luuk d aroundbut he wasn't absolutely sure. Others in the room agree d th a t ese animalsdo leave their burrcws for varying periods of tfme, Obrebski at enough fish to say yet. Ourkln also had noticed an Inshore/offshore then convnentedthat exclusiloncages mfght not be an effective tool. Smith migration of somedemersal fishes. For the moment,nat muchd Iscussian repifed that he wasaware of the prob!emsand hopedta comeup with same was heard on this subject It was brought up a little later>. correction factors. Glen Van Blaricom brought up the subject of core samp!es once again and Obrebskithen mentfonedthat a student, RalphJohnson, studied Tamales said that a fellow student at Scrlpps recommended laying them on their Bayand foundthat benthic communltlesare often associatedwith certain sides after collection to avoid traveling by the animals, thereby affecting sedimenttypes. Therefore,the speciesdiversity of a particular benthic the I r normal spat la'I d fstr I butlon. If an animaI responds to gravity, it sampleis dependentonthe patchinessof the substrate.Some organisms can without changing Its vertical position. Word said that they set the are associatedwith severaI sediment types while othersare morespeci f 1- samples ln dry ice and freeze them as fast as they can. Feller mentioned cally associatedwfth oneor two. Onemight consider sampling the sur- that freezing can "pop" someof the soft-bodied animals, which ruins them raundilngsediment along with the fish and benthic Invertebrates. for later Identifications. Ward suggested capping the sample tightly but agreed that frozen samples are difficult to identify. Another problem Feller askedhow Oregon State Unversity's samples are preserved,to which arises with large or long animals. Whenthe core is sectloned, these WendyGabriel replied that they are washedthrough a I-nvnmesh screen, animals may appear in several of the subsections. Haw does onn place Ihe put In formatIn, then changedto alcohol. anImal'? This should be standardized although many people now use heads as indicators of total body placement. Wardwondered about the value of geological analysis of sedimentunder the current technfqueof droppingthe sedilmentsIn hydrogenperoxide and Sandy Liipovsky mentioned a problem with polychaetes falling apart afler baf I ing ouf the organ les. He claims that the invertebr t. d 't being stored In the stomachs. The cambilnatfonof digestive fluids and thata in kind oof substrate,they see the detritus,vegetat lan, etc. Current I y, formalin is dynamite fa saft-bodied animals, Wordagreed but Gabriel however,there Is no better technique. It might be worthwhilefor some- uses a technique whereby the guts themselves are not injected but rather one to workon a newtechnique for sedimentanalysis, the stomach cavity, missing the gut. The entire fish is then stored in formalin in case a student later decides to do a marphometrlc study. They Gabriel conznentedthat "... In someInstances, If you can Identify sediment use a 10$ formal'!n and seawater preservative. Upon hearing that, Word frcm the geoioglee I point of view, that wl I I g fveyou someclues ta the reccvanended that they lo~er the strength to 5$, then rinse the samples dynamicsof the watermass movement fn that area." For example,different and convert to alcohol, Gabriel mentioned the volume af fish and lack of grain sizes mightbe foundbehilnd banks, In areasof upwellfng,associated time for conversions to alcohol. with deepwater currents, underwater transport systems, etc. Thesethings mayaffect the short scale distribution af species. A discussion of buffers followed, Feller mentioned Hexamethaline ielrnmine wh'Ich works fine but Is expensive. Word expressed the views of many by ObrebskI pointed out that BobWhit lash af WoodsHole recent 1 ycompleted saying that Borax works just fine and Is cheap. There also Is some a thesis very pertinent to this questionof dfstrilbutfon of Infaunal natural buffering by seawater, which also reduces the osmotic change organIsms, mostly polychaetes,and their relationships to sediments. He experienced with formalin-freshwater mixtures. tookcores very carefully from Intertidal areas, froze them, and very carefully sectlonedthem. Thenhe measured the three-dfmenslona1pasltlons baevastu discussed that ln many ways epifauna may be more important as of the organisms,sampled the sedimentaround them, and the sediment fish food than infauna. Little quantItative Information is known aba«i epltauna such as seasonal migrations and year-to-date changes In nbu»dunce.

70 71 Lookingat seasonalmlgrat lans of somedumersa I f lsh, weassume that It trying to quent I fy the data. It Iso' f possibfo since the area coverr Is relatedto scmethlngphysical as temperature,rains, storms,etc. can't be measured and we don't even usual ly observe how the s le1 PerhapsIt Is theepf fauna that is sensitiveto envlronmeniafsignals and travel lng or If It has tipped on one runner, or It ft Is digging into the demersalfish, In turn, follow the eplfaunaifood sources. Gabriel the sand and sampl'Ing benthic 'Invertebrates, etc, cameback with anothertheory to explain someof the Inshore/offshore migrations,Perhaps during storms, the fish move offshore, sacrificing thefr foodrations for stability, expeciallyIf theilr habitat trasbeen In relatively shaflowwater. In colderwater, the metaboliicrequ Irements wouldbe lower and the fish could afford to reducethe food ration. This maybe more desirable to a fish thanbeing covered up every few days by actfons, Slmenstadreturned to the problemof sampflngeplbenthos by explaininghfs problemof trying to sampleln an areanot suitable for an epibenthlcsled. Someof the problemsare shallowwater, nursery areas, uneven bottoms' eelgrass,etc. Hisgroup Is experImentlng with an eplbenthlc pump which, whenImproved, may be a veryuseful sampler. It capturesthe Juveniles of someinvertebrates as weil as the eggsof harpactlcoldsand gammarlds. Obrebsklwondered if pumping through a rotormight the organisms. Theanswer was yes but somepumps have collection chambersahead of the rotor unit andsome ne~er models are diver-held"vacuum"-style. The vacuumpumps are not too good in deep water, however, WordIntroduced a new subject by statfngthat sometimesIt Is Interesting to go beyondIdentifying animals by sorting themby sexcomposition. As an exampleof this, he stated that somemale cumaceans and ostr aco d s ar e peela ag I cI dwe Iers while the femalesare benthic. If one examinesa stomach f uI! ! of males

I 72 73 SESSIOIV LEADER: PARTICIPANTS: Robin LeBrasseur T on y P hill i ps Beverley Kask John Johnson Julie Ambler Catherine Terry John P, Ellison A LABORATORYMETHOD FORTf EANALYSES Ol FISH STOMACII CONTENTS

Beveri ay Kask and John 5ibert

Maferials and Methods laboratorryteeirnirfwe after the stomach s hadbeen dissected f rom f frr f sh,I theywere dried, using a damptowel, we I ghedon a Mottler PI62balance and putIn PetrI dishes.These were I II ledwith water arid p acedI on a mmgrid undera dilssectlngmicroscope. Surgical scissors were used to openthe stomachanda subjectiveestimate was made of the percent capacity uti I ized bythe food bolus. The contents were then removed from the stomach usirig a probe.Gentle agitation usua I yI separatedthe food i turnsand spread I Iiem In thedish. IJslngthe grid as a guide,the samp le couirl then be miived back andforth underthe microscope.Each f leld wasexamined and ind i vlij»aI food itemswere ident I fled and measured to the nearest miI Iimetre. Manfpular i on of thefood organisms wasminimal and was usually necessary only when temptingto makeidentifications. The percent of the contents In niiaiivanced State of digestionwas estimated subjei tivel y. . Wh. ere subsampllng of the stomach contents was necessarary, due to its volume, or large numbersof diet fo be used In analyzing the results, These include calcu lal ion of ltii lr~- items, a Folsom plankton sp I ' i tter er wasused, Subsamplinguas continueduntil quency of occurrence of each food organism by spei-ies, group, or ;ize r,iii!e 100 of thedominaiit food organisms could be counted, or un'il thevolume and calculation of the biomass of each food Item, per fish or In to!al In- reacheda moremanageable Size. Ailernatel in caSes formation may be gained on energy rsquiremenis and food chain Iiu.ture;, o sma oodorganisms e,g. tunicates, the subsampilngwas carried both w Ithin the estuaries and in the open waters. By uf I I izliii! IIu uzi outby counting crily a poitioii of thedish. In bothmethods, the total num- guidelines fo measure the food organisms and those taken In lhe ziioiil,iiihluii taws, a comparison may be made between the food species ave i lab le end I liase f acier. The wei ht of ated by multiplying by the appropriate sp ! il9I ftl taken by the f lsh. Once fami I iarl ty iS gained In using the keyS to t lie g of the dampstomach shel I was recordeil aiiaiid thl s va ue, subtracted from the we wel g I it of the ful I stomai;h,gave the weight of ths food various food groups, the time required for anal ys Is Is greatly reduced. TheSe methOdS have been a practical success and were used to describr i!li ,7ee a~ing nndann!yance Of nnbn--reaarding Of datawaS Oi diets of f I sh f roin the Eraser Env I ronmuiit Cariada, 19!S !, Nanaima Lnv i raci- on whichthe iiameof the toedorganism, the numLieiand IIgliial iy on Iab sheets ment Canada, 1 974 !, CampbeI I Goodman and V room, 'I 974!, Squamisli Erivi r unmeant !owevsr,this provedto betoo cumbersome whenhandling engths were written. Canada, 1972!, Somass Kask and Parker, 1974!, and Cowi chan in preparation! stomachs. Handtabulation andfypl f t. bl large numbers af estuaries. hoursof preparation.Consequently p ngilt o wasa necessary es foi pub!to ic«lion required many cordingfarms and devise a codeto handlethe analysisodesign computed re- stomach analysis data. ! amounts of LITERATURECITED Environment Canada. 1972. Effects af existing and proposed industrial Oneach coding sheet were recorded the samplamp lnng area,area gear, stcit lon number, development on the aquatic ecosystem of the Squamish Estuary. I I,heries species o of sh f1 s analyzed,length mm!and weight gm>oF th~ f I h of the stomach s o e s , the number Service, Vancouver. stomach,scale number,age, capacity of thee sstomach omac, > the weight mg! of the stomach fullu sand empty,the percentageof the content th a t 1974. An environments I assessment of Nanalmo Port el ternal ives. Lands were dl Directorate, Ottawa. gested,and the numberof foodcategar les. s. Each ac food ood category con- slsted of a catec gory or codeco e, the is size I range mm!and the nvmbercounted. Lip 1975, F Isher les resources and food web components of ths Fraser Ri ver to 23categories could be listed from any one stomach analyzed. Estuary and an assessment of the Impact of the proposed expansioii ai the Vancouver International Airport and other developments on these resources. Thecategory code itse I f wasdesigned to incI vdef Issh , ph y to op I ankton,kt zoo- Fisheries and Marine Service, Vancouver. plankton and benthos.os. F our separatesections of the codewere set up, based on a threebyte alphanumericcade. Thefirst sectiec an, num b er-number-number, Goodman, D., and P.R. Vroom. 'l974. An assessment of the Impact of proposed nc u es the ish of the marine~stars of this coast, sfartlnar ng withw and 001 marina development an the fisheries resources on the Campbe'll River endin g w with 999. . e Th pagenumbers from Pacific Fishesof Cand b k 973! wer aa y ar Estuary, Environment Canada. fisheries and Marine Service Tech. Rep. wereassigned to eachspeciles. Approximatela e y spaces 300s have been Pac/T-74-13. reserved ata e the endof the cods for freshwaterspecies. 999 f I t "fish eneralu. T s g ven a g . he secondsection ls reservedfor the benthos,and the Hart, J.L. 1973, Pacific Fishes of Canada. IiSh. ReS. BOard. Can. Bull. codes are given as number-letter-n ter-number,e!icompassing 2 600 spacesfrom OAO !io. 160;740 to 929. his section Is not yet in use, Themain bod of fh d I letter-number ils the y o e co e, etter- e sectioncontaining the phytoplankfon,zooplankton, Kask, B.A. and Rabert R. Parker, 1974. Data Record. Alberni Inlet fishes, foramlniferans, radiolarlans ci April 23 to July 20, 1971. Their distribution, species, size/age com- others. There are 6 760 s a ciilates, coeienterates, annelids and many p ces In this section,and it expandsinto fhe next, position, and stomach content. Parts I and 2. Fish Res. Board Can. letter-number-number,whichcontains another 2,600 spaces. MS Rep. 1311: Spacingof assignedcodes was arranged so as to allowfor f eac group,e.g. copepods.Identifications a owmay orthus uture bs carried e>pension to group, species, or even life stage.

Discussion

While inifiali y requiring re u r' the expenditureoF

79 examinethe digestive tract of al I fish from the top of the esophaq>r-to the junction abovethe pylor1c caeca. I put stomachcontents Intr>a wrlrh ti iy ai I or J,rr>isms and record my findings. I organlre mydata for a I-year period of time 1July 1975-.lulyI'r] >! I know total numberof food items for each species of fish and from Ih,>l I METHODSUSED IN STUDYINGFOOD HABITS OF OREGON'S ESTUARINEF ISHES can computepreferred food Items for each species by percent. for example; examined71 starry flounder stomachsand found 851 food itoms. Preferr-ed food Items were as follows: corophid amphlpods53.6'4 ~ gammaridamphipr>rjs 13.65~ juvenile clams II.54 and so on. John Johnson Oregon Deoartment of Fish and Wildlife P>ad3 basic sources of reterence materi~i. I used the third aditi ~rr !I Ti I lamook, OR L!ght's Manualwhich is an excellent sourceof informationon invertebrates of the centrat California coast as well as the Oregoncoast. Joarr I'iyn pro- vided me with copies of detailed drawings of organisms she anlicipaterl miqhi My name ls John Johnson and I am w1th the Oregon Dep~rtment rf Fish and Wild- be found in Tiilamook Bay and I found these mast useful. I oftentinr, life. I am nvolved with the Tillamook estuary study, which Is a flnflsh anr referred to a reference collection of organisms found in Tillamook fray which shellfish distribution and abundance study. was composedby myself and Margaret Toner, OSUgraduate studr>nl. Along with our normal duties I started examining the stomach contents of var- Here are somegray areas I have questions about. I would like to knowhow to ious species of fish out of curiosity at first. I recorded my findings In stop the digestive processmore rapidly tlran I do with present method.;. vague terms 'like snails, shrimp, pili bugs, etc. Our first annual report wa< would I Ike any suggestIons you may have that would speed up the examination due and I wrote a short section about the food habits of fish In Tlllamook process. Wespear black rockflsh along jetties uslnq SCUBAgear; however, Bay. Suprlsingly many people thought this type of work enhanced our project would be Interested In finding other ways to capture rockflsh In areas like In general and I was encouraged to continue the project ln a more organized ibis. manner. Here are somehelpful hints for beginners starting work In stomachar>alysis, was a wi ldl I fe major at Oregon State University and I did not have one Goto experts and ask for pointers in ail phasesof the process, Find and course In invertebrates, so I knew I needed hei p from experts. I went to use all keys you can get your handson which pertain to the food organisms Joan F Iyn, Oregon State University, and Sandy Llpovsky, National Marine F1sh- you happento be workingwith. I have foundmy referenceco!Ioctlr!n lo be er les Serv I ce. They were both very pat lent and eventua I I y tiiey started me a real time saver In the keying process. ln the right direction.

I' ve been working with stcmach analysis, on a part-time basis, for over a yea now but still consider myself a beginner at best. I will explain the pro- cedure I use for examining fish stomachsand give commentson gray areas have questions about. I will give some suggestions that may help some of you that might be beginners as I am.

I am examlnlno 5 species of fish: chinook salmon> starry flounrier, English sole, surf smelt, and black rockfl .h; most of the fish examined are juveniles Wecapture fish us'Ing g I II nels, Prewls, beach seInes and SCUBAqear.

Juvenile starry flounder and English solo are preserved In a 10$ formalin .nlulion while chinook ar>rt rockiish are injected wIth pure formalIn to stop the digestive process as sour> as possible,

81 somean lmai s a i wayswere In the enter'lor part af the stainach, whli ii would imply feeding in the net. Copepadswere suspected, but they weie fou«d from the anterior to the posterior part af the gut. The numberof each pi ay taxa was recorded,but the variety of prey andpresence or at>;rnce in the predator was more Important Tabi e 2, Pearcy and Amb'ler19!. A higher percentageof unidentI fi ablegut contentsai.curred In ,in,lI I i ratta I Is than ! arger f I sh of 'Ihe samespeci es TabI e 4, I'iinrev iri I 4mbI or THE PREY DF D EEP- S EA MACROURI D FISHES 1974!. The unidentifiable mater Ial was cal led "grungeu arid in Ill .' oases OFF OREGON ihe orig'In Identified: orange crustacean remains from pelagic crustaceans, fish or squid eyes, f Ish scales and vertebrae, andmud. h fi wr omruonI y I i i' s J uI I e W. Amb1 er occurr'Ing Items remained a mystery such as hooks and "copper w School of Oceanography Oregon State University Corva I I Is, OR Identification af Prey Species For food habit studies of fishes, it Is helpful to be familiar with the This paper discusses the problems of Identifying prey of deep-sea potential prey, For the macrauridflSheS, bentiiiC i«vertebra!es aught macrourid f ishes. The results of this food habits study are pubf ished in beam trawl s and meso- and bathy-pelagic nekton caught in mi ii-wafiir by W.G. Pearcy and J.W. Ambler n Deep Sea Research21: 745-759, 1974. trawls were major prey Items see Table2, Pearcyarid Ambler 1914!. The prey of the deep-sea niacrourlds includes manytaxa that Inhabit the SampI es were el so observedfrom a plankton net towedabove the beam deep-sea floor and meso- and bathy-pelagic waters. Several major taxa trawl, However, there was I Itt I e corre I el ion between copepodspc c ies were Important prey; crustaceans, echlnoderms, molluscs, polychaetes, In the f lsh stomachsand those In the plankton nets. Gaussia prlncc~s and fishes. Taxa also observed Included: foramlnlfera, nemutodes, caught ln the p Iankton nets wasnever observed In the f ish stomaciis, echlurolds, and plants, With such a wide varfety of animals and the ilncompietenessof deep-sea taxonomy, several groups were given ta Identification of the prey to species may not always be necessary. From specialists to Identify. However, experience in sorting and Identify'Ing food habit studies, one wants to discover the major taxa af pray and its benthic invertebrates from beam trawls helped preliminary Identifications. habitat, Wewanted to know if the macrourlds ate eplbenthas, Infauna, Recently publisheit references will facilitate future faxanamlc work for or nekton. It may be adequate to knowthat a particular species and mast of these animals. s Ize class of rattail eats deep-sea palychaetes and holathuroiiis i a!her than nekton. But, with In a major taxa, somespecies may be mare impor- tant food Items than others. I or example, the rattails only ate two of Data Recordeij for Each Fish Observed the haiofhuroid found In Cascadla Basin, Species ident Ificatlori of pelagic prey such as shrimpsand cephalapods was correlated with the For r«aciourids, aii important fact Is whether tiie sfomnch Is everted, full, distribution of these anima!s In the water column. The occurrence of or errpfy, Since the swlmbladuer of a rattail expand wlie« brought ta these mesopelagicanimals in ihe guts af the rat fai'is raised questions the surface, the stix«ach Is often everted. The percentage f everted about their feeding behavior. Da rattalis migrate ta mesapelailii waters stomachsvaries irilh species of macrourid lable I, Vearcy and Amb!er or do they eat the mesopelaglc animals as carcasses? 19?4!, Data on fullness of the stomach in terms of I/4 ~ I/2, 3/4, or full were subjective and not very useful. The sIze anu spei:les of The fol I awingis a I I st of taxonomicreferences which are generalenoi gh macrourld observed were very Important, bei-ause food habits changed with for Ihe bioiog1st whaIs a no«-special1st. For deep-seapoiychaetes, these factors Table 4, Pearcy and Ambler 1974!. holothurofds, copepods, and amphipods, taxonomic special ists are essential. These references were recommendedby people working with The most useful data far describing food habits were wet weight and these taxa an projects at the Schoolof Oceanography,Oregon State frequency of occurrence of the prey taxa. Wet weights give relative University, Corvallis. Importance of the major taxa wh'Ichoften Include several species. Frequency of occurrence data can iepresent each species and type of prey, The wet weights aid not correspond very well w1fh frequency of occurrence Genera I Table 3, Pearcy and Ambler 1974!, fhe prey species of larger mai.rourlds dominate by wet weight, when all size classes of a species ure combined. Smith, R. I,, and J. T. Carlton, eds. 1975. Light 's manuaI; Intert I dal The position of the prey In the stomachwas also recorded ti: discover If invertebrates of the Central Cal lfornla coast. University of Cal i farnia Press, Berkeley. 716 pp.

B2 83 Polychaetes Crustaceans Hancock,DanI I. 1969.Bathyal andAbyssal Poiycaete annel ida! from Copepoda thecentral coast af Oregon.M,S, thesis. Oregon State Brodskll, K.A. 1950. Calanoida of the Far Fastern Seas and Pale Un!versi ty, Car va1 I ..I 121pp. Keyto species! th USSR. Zaologica I Inst itute of the Academyo S Hartman,Olga.1968. Atlas of the Errantiafe Polycaetaus AiineliJsfrom of the USSR. No, 35. Moscow. 441 pp. Irarislated f r«iii California.Alian Hancock Foundation. University af Southern Russian by israel Program for Scientific Translations, California,Los Angeles. 628 pp. keyto species! Jerusa ere, 1 967. AvaI I ablefram U S.. Departmentof Commerce, I h for Federal Scientific and Technical information, Hurtmnn,Giga. 1967. AtI aso the Sedentarl ateP yc!rani il auAnnnl I ds Springfield, VA, 22151. key to species.! fromCal I amia, Al lan ilancack I auridaf loii,Irrri var s iy i ot Owre, and Maria ioyo. 1967. Copepads of the Ilarlda Current. SOuthernCali for»la, La. Angeles. 812 pp, ke>tO siiecleS! Fauna Car!baca, No. I. . pp. 1 37 . Very qoad adaptatian reer Rase's key ta genera.! Molluscs Rose, M. 1933. CopepodesPei aglques. Paul LechevaI ler, Paris. Abbott,R.Tucker. IDUB. Seashoils ofNorth America. A guide to 374 pp. In French.! tofield species!Identiflcatlori. olden Press, NewYork. 280 pp, key Ajrrp hEpode Abbott,R.Tucker. 1974. American Saashells: Themarine mailusca of theAtlarific and Pacific coasts afNorth America. VanNostrand Bernard, J. Laurens.n . 1969. The Faml I lns and Genera of Marine ReinholdCo., New York. 663 pp, Keyta species of shelled GammarildeanAmphlpoda. U.S. National MuseumBulletin in 771. molluscs.Descrlptloris of cephalapod species.> 535 pp. Key to genera.! Ak!mushkln,1.1. 1965. Cephalopods of theSea of the U.S.S.R, T ames E, and Hans-Eckhard Gruner. 1973, The Families and Generae t of Hyperl Idea Crus acea: . Am mp hlpoda!. Smiihsonlan AkademlyaNaukSSSR, Instltut Okeanalogili Translatilan>, Contrlbut ions to Zoology, Na. 146. 64 pp. Descript ion af 223pp. Help ulfor squidbeak Identiif Ication.! faml I les and genera. ! Clarke,M.R. 1962. The I dentI ii cation ofCephal opodnBeaks" andThe Relat1onshipbetween Beakand Size and Total Body Weight. Dickinson, John Josepse h 1976. Twa Zaogeographlc Studies of Deep-Sea Bullet ln of theBrit I ahMuseum hiatural History! Zoology, !3enthic GarnmarldAmphipods. Ph.D. Thess'Is. s. Ore regon on State 18 IO!: 421-480. Partial keyta famlI les.! University, Co rva I I I s.. 117 pp. Includes species I rats for stations in CascadIa Basin,! Keen,A.Myra and Eugene Coen. 1974. Marine MolI»scan Genera af WesternNorth America. Stanford Universfty Press, Stanford, 126pp. Keyto generaof shelled molluscs only.! Decapode Roper,Clyde F,E., Richard E.Young andGilbert I . Voss. 1969. An Rathbun, Mary J. e ta I . 1904, Decapod Crustaceans of the Northwe'I I Ifustr'ated Key ta thef'aml I les of theOrder Teuthoidea Coast of North Amerlca. Harriman Alaska Series, V o I. X, Crustacea. 337 pp. key to species.! 32 cephatopada!. pp. Smithsonian Contributions to Zoology, No.13, Schmitt, Waldo L. 192!. The Mar fne Decapod Crustacea of Cal! farrila. Young,Richard E. 1972.The Systemat!cs andAreal Distribution of University af Cal lfarnfa Press, Berkeley, 470 pp, PelagilcCephalopods fromthe Seas off SouthernCalifornia. key to species.! SmlthsonfanContributions toZoology, No.97. keyto spec es> Wasmer, Robert Allen. 1977. Zcogeagraphyof pelagic shrimps Natantla: P enae nae idea ea anda Carldea! ln the North Peel flc c econ. Ocean. Ph.D. Thes1s. Oregon State Unlvers I ty, CarvelI ls s, 237 . pp. key ta species.! Eehinodezrna

HoI othu roles

Carney, Robert. 1976. Patterns of Abundance and Relaf ive Abundance of Benthic IIal at hurolds or> Cascedl a Bas1n and Tuft 's Aby";a I F'I aln ln the Northeast Pacl f ic Ocean, Ph.O. Thesis. Oregon State University, Corval I Is. 180 pp, No key.!

Ophi ura I ds STOMACHANALYS I S METHODOLOGY:STILL LOTSOF gUESTIO'NS

Kyte, MIChael ~ A. 1971. ReCerr OphiurOIdea OCcurring off Oregorr, U,S.*, Pages 65-83 In Ecological Studies of Radlaact iv i ty in the Columbia River Estuary and Adjacent Paci f ic Ocean. Progress Catherrne Terry Report I July 1970 through 3O June 1971. Submitted to College of Fisheries, University of Washington U.S. Atomic Energy Corlrrisslorr Contract AT 5-1! 2227. Seattle, WA Schoo I of Oceanography, Oregon State UnI vers I ty, Cor va I I I s. Out of print. key to species,! There are two objectives In this presentation: One ls to describe lhr. rne- thodology currently being used In our food web studies at the University af Fishes Washington's Filsheries Research Institute. The second is to bring up for discussion someof the questions and problems for which we haven't found adequate solutions. Hart, J,L. 1973. Pacific Fishes of Canada. Fisheries Research Board of Canada, Bu'Iletin 180, Ottawa. 740 pp. key to species.! Methodology Iwamoto, Tornio, and David L, Stein. 1974. A Systematic Review of Adjacent Waters. Bulletin of the California Academy of Sciences, Preaerrrafionof apeoirrrene,F ishto be kept for stomachcontent analysis are No. Ill. 79 pp. key to speciles.! placed In 10$buffered formalln In the field. With larger fish, formalin is Injected Inta the abdominalcavity within 15 minutesof capture, Theamount Ml I ler, Daniel J., and Robert N. Lea. 1972. Guide to the Coastal of formalin injected is recorded and iits weight Is subtracted from that of Fishes of California. Fisirerfes Bul let ln 157. State nf the fish when the fish Is weighed. Fish are returned to the field lab where Cal I fornia, The Resources Agency, Department of F Ish and Game. length, weight, and sex data are recorded. Small fish are taggedwllh a spec'imennumber and a station location code. The tag Is placed underthe key to species.! operculumand up throughthe mouth. Stomachstrom larger fish are dissected from the abdominal cavity, cutting as close to the esophagusas possible and cutting j »t posterior ta the pylorus, The esophageal end is tied by a string with a tag labelled as abave. Laboratorypremed re.The stomachls removedfrom the fish and drieri off. A dampweight Is then taken to the nearest tenth of a gram. The entire stomach contents are removedand placed in a dish and the empty stomachis weighed. By subtraction this provides a total stomachcontents ~eight In- cluding unidentifiable material and fluid. An evaluation of the stomach fullness ls madeand given a number scaled from I empty to 7 distended!. The stomach contents are placed In a dish marked w1th a grid and sarled, separating all unidentifiable matric from recognizableprey orgarrisms.A subjective evaluation of the stage af digestion sca'ledfrom I all unident- ifiablee! to 6 no digestion! is made at this time.

86

87 Prey identification is madeto the lowest taxonomic level possible given the seemsessential that we knowexactly what species of gamr»arid,are bring prey- digest'Ive state und the ab'Ility of the sorter. For example, crab and shrimp ed upons ince there I s sucha great d Ivers I ty of gammari ds I Iv Ing I r>a wit!a fairly easy to identify lf they are Intact, so these are faken to species variety Of habltatS, A por,Sible alternative would he to Irlentlfy lhe func- if possible. Polychaetes are generally beyond recagnitlon but wa try to take tionall role eg. pelagic, epibenthic, benthic:! of a prr>y argar>is>r>wr>sr e rnorph- these to tamlly If we can. Amphlpodsare carried ta suborder garrmarids, aiaqical characters, are definitive. This, however,definitely camplicafes caprellids, and hyperilds I but no further, No attempt Is madeto Ideniify coding thses organisms. a!her small crustaceans beyond the groupings of harpactlcold, calar>old, and cyclopaid copepods, rnysids, cvmaceans,tanaids, and euphausllds, Isopods ln addition to the taxonomic dift levity, there is the complical inri fr».lr>r r>f are taken to suborder when possible. Hlalluscs are often relatively easy to d1fferent levels of digestion. It Is frequently impo sible ta ideality 3 Identify and are taken to genus and species, though Identification as a prey item beyonda broadcategory becauseof the advar>cedstage af di la.,fion qastropod, pelecypod, or amphlneuran fs most common. It Is In. If ln other stomachs we can identify organisms ta specirs levnI how does one analyze the data? Do you thraw out ail sperlmens for whl>h the After prey have been sorted into groups and identified, they are counted. prey are too we!I d!gestedto be recognizableas Individual specie.,? Counting can be a problem If the prey are pieces. In this case only a whole organl sm Indicator--l.e., someihir>g tr>e anima I has one of--Is counted. For frrganiamepurta--how do you makecounis of prey organismswhich hy !heir example, heads for crustaceans, opercula or apical whorls for gastropods, ture are not eaten whole sucl> as pieces of a Igae, sponge, hydrol d., br yozaans, hinge areas for pel ecypods, centra! disks for ophlura iris, and Ar I stot le's holothurald gl I Is? Wehave been making very subjective e ! 1«>a!a; of «! a! i lanterns for echlnoilds, When a prey was not eaten whole and onl y a par t was "bite-sized" and then counting pieces this size. This Is quite arhi trary and Inqested, the parts are counted and given special coding that indicates that In somecases Impossible to da. Recently, we had an Fyrr>phrgabir>r»r;fr»r> it was only a par t. This Is especla I ly useful for f I sh that prey on cia>n WhlCh WaS full Of SheetS Of VfVrZ and PrZrf>fr>JZVZend there WaSna way IO eSFI- siphons and don't take the whole clam. mate a numberof bites of algae taken. In cases like this, our current methodof trying to get both counts and weights breaks down. After the prey organisms have been sorted Inta group- and counted, the weight of each taxonomic unit 'Is obtained to the nearest thousandth af a qram, The stomach contents are then placed In vials and kept for possible further Subsampllng identlficatlon of someof the difficult prey groups, such as gammarld Canyou svbsamplewhen the stomachIs packedw 1thtiny prey? Whenstomach amphipods, by experts in those taxonomic fields. contents are removedfrom the stomach and placed ln water, they da nai spread out nice and even!y. Instead they tend ta be very tightly clumped and one Stomachana lys I s data are recorded on computer-format farms wl th 10 dig'lt needs ta careful'ly tease the organisms apart. It 1. the separation of the numeric codes for both predators and prey F'Igures I a ib Ic! prey that takes the time with these guts. If we wereto simply take half af the stomachcontents and analyze them, we run a fairly high risk of error Time element for guts. Analyzing fish stomachcontents using this method ls because the distribution af the prey organisms within the gut content often slow work. 'Weaver age '! hr /stomach. This average Is only thi s low when we Is not random. It Is fairly commonto see clumps or bands of cer.tale prey include the time It takes to da an empty stomach, which Is about 5 mInutes, types In the stomachcontents. For example,with a plankton feeder, mastof The minimum time we spend when a fish "a s food in its stomach Is about 20 the stomachcontents may be a mixture of copepods, Oikapieum, chaetognafhs, minutes. Juvenile flatfish and large rockflsh eating large prey organisms usually fit Into thIs time cateaary, The maximumtime we spend per full gut and fish larvae and have a wide band of nothing bvt myslds placed somewhere Is 4-5 hours for large fish ca!lag lots af small prey. Th'ls is commonfor In the stomach contents. adult embiotocids and processing time for these fish Is very lonq. For example, one Embiotoea fates'alia I did recently had 915 grmmarid ampipods In Theseare the questionsthat we stl I I haveabout how It is best to do fish its gut and took 5 to separate and count all the organisms. stomachcontent analysisand I hope that they wiI I be part of the discussion that follows. Problem Areas

Identification. How far must you carry prey Idenlificatlc n2 Ideally, Ident- Iflcat ion should be made to the .>Pucieslevel except where damageby diges- tion has destroyed the specific ct>ar*cters. I'ractically, this is uxlremely difflcr>lt because of the taxonomic difficulty of many of the prey groups, The sorted prey would have to be given to experts in each taxa~amic field, a single ernblotocid may have 800-900 gammarid ar»phipod in its gut and it would likely take several months just to ider>tify these organisms form one stomach. yet If we' re looking at ir>terspeclfic competition for food, lt

89 EC0LOGYRIIO OISTRIBUTION OI PINKYsoISID I ISIIL'S I'ore ',2e0, 0 aI g Coylegeof Ilsheriesfplsheries ResearchInstitute Steaaehexaa.-prey freq. Oniverslty of ifashlnaton

V Vt Species

prey organlsa taxa iinitial sortinn!

Prey species final deterainatlon!

geo

4I I @SO

4 D V4 4DOI Spar 2

I D y D egg. D 2 w <48 '4 I' I 4 4 FigureIb. r-IomachoonIysls fo"

91 I4IUI Pa.

x Z

METHODOLOGYUSED IN STOMACHCONTENT,ANALYS I S

John P. El I lson Occidental Col lege end Southern Cal Ifornia Edison Thermal Effects Laboratory Los Angeles, CA

At King Harbor, one aspectof our researchprogram is to examinethe f .uding habits of approximately30 speciesof fish. Thesef lsh Include epi faunal azers pesclvores I planktlvores and herblvores. Their stomachconte~ts are being examinedin order to determineiheir diets and these data will be ana- 0 4- I yzezed with Occidental's IBM 376 computer using a program for discr'Iminate Vt analysis. These results will 'In turn be correlated «Ith field observe tons, Vl tg The proceduresand methods used for the collections and handling of the fish Irr are as foliows. 1. The fish are collected by SCUBAdivers using gill nets, pole spears W I- and collect'lng bags. WUI- I- VIX 2. After capture, the fish are placed into a bucket without water and are U. allowed to suffocate. A solution of 20$ formallne ls then Injected into X Q JU the gut to stop the digestiveprocess and preserved in a 10$formalin- sea water solution for at least 4B hours. Z III O I IU I 3. The fish are then rinsed in running water for 2 hours arId afterward UJ P UJ placed In 704 isopropyl alcohol. U WIE 4, The fish are weighed, their lenqth ls taken, and they are lissecled tp 0 Z Z0 VI remove their StOmaChand InteSt irre, and their Sex IS nated, OILZ X O I- I- 5, The contents of the stomachand Intestine are examinedseparately with a IllO IUVI variable power dissecting microscope. The food 'Items are keyed out to tx IU the lowest taxon feasible and their number is noted along with their UIZUI I/I estimated percent volume. U- Becauseof the relat I veiy poor condition of the food Items in the ilnres fine, U IU only the data fromthe stomachcontents are usedin the statistics'I analysis. Q IJJ The information from the intestine Is used only In complI ing a I i st nf food O U IUIUO organisms for the tish.

92 The usn of dl scr iininnf e analysis a II owsus more leeway than manyother statis- t ical tests, in that both eriuinerated and measured dale may be uti I ized. For exainple, the diets of 7 or nor e f ish may be compared usin:I such data as recon- sti ucted welglit ol the pr oy pecles. volumetric displaceinent, percent occur- rence, percerit volume of sloinuuii, uti:, a! wel I as the nurneroiua! occurrence oi the food Items. Just a measured data provides a more vul id Interpreta- f ion of gut ariilysl s so a statistic employing this type of data will result in a more useful test of difference or similarity.

In calculating our variable we muliiply aha rumber of each faad Item In the load grc ups by their estimated nnrcent volume iiopefully ihls will enable us to weighthe purely ni meri caI data In order to get a rriiire valid r epresen- fatlon of the relative value af the various food groups. DISCUSSIO'N;SESSION 3I LABORATORYPROCEDURES AND IDENTIFICATION Another advantage of di scriminate anal ysii s is that any ane fish need not have every food group repiesented ln its stomach. This allows lhe rale»tlon nf minor food groups in Ilia ana I yeIs r st her than I'he ir conihlnat i on into Theimportance of a

95 Dave Levy mant oned the problem of dropping f Ish espec a I tt Id ! considered stomach analysis methods Including many of the same problems being dlrrec t iy Into formaI ln for presevat Ion as It w II I often Induceregurgl ta diSCuSSed. He COntlnued that ICES and FAO haVe alSO reviewed theSe methOdS tlon and an ntermedlate anesthetic is necessar and that European literature should be checked, espec'lal!y the documeniat Ion y ~ of food habits varlab'It ty In space and time. He also noted that thor' Is crying need to summar'Izethe existing data on fish food habits and orlent Bruce Mi ler requested Information of thee Nanalmana mo group regarding prey cocodln ng errors. v Kask verified that they ran crass references current and future studies on more practical Information, cl ing the luck of amongtheir stomachexaminers with no silgnlfilcanterrors, thoughHealey knowledgeof North Pacific squid resources as either food organisms thonselves notedthat thIs is difficult becausesubsequent exaenlners ended up with or regarding their prey. fewer and fewer organismsto Identify. Sandy Llpovsky asked the Nanalmo group If they used a wet weight: dry weight Backto a dl'scussIon of measuringweights, J lmCong etonasked I f anyone conversion factor no! and whether anyone had looked at annual or seasonal hadInformation showing a progressive decrease In dry we ghtwith preserva- variations ln such a relationship. No one knew of any data. tion In formal n. CalI Iiet ment onedthat zoariclds shrank101 d th foodor ganlsms 5$ to Oxfor a fewdays, but thendecline s ran quickly an e r John El! san mentioned that separation of the food bolus without breaking up the animals can be a problem and said that Re1sh's people used an extremely taperedof f; hesuggested using a vo umetrlcInstead of a gravimetric f ne~eshed screen to wash lt over, separating the food organisms wlthnul too method,c'Itlng the drying of Oikopleurato essentiallya y nathna In ng. . Johnson o nsan suggesed that the volumetric methodwas too time-consuming. much damage. He also sa d that he had never observed speared fish regurg'Itat- Slmenstadsaid that the volumetrIc methodwas also less precisethan Ing and that allowing them to "suffocate" appeared to be preferable to direct taking weights, and Terry thought you tendedto contr/bute morewater preservation In formalin as far as reducing the chance of regurgitation. ta the volume when you added an organIsm. Stephens concurred. Considerlng stomachfullness, Cail let mentionedthat In studiesof Lolilgo Word asked if anyone had ever seriously 'looked Into nel contamination of fish stomachs,use of fullness indexfrom 0 to 4 prov dedgenerally the same stomach contents, by consumption of e'Ither net-caught Items or other fishes' regurgitated! food Items. Laevastu reported the Incidence of large and small conclusions as the percent fatal dry we ght with fewew dl" screpanc I es. Robinn eBrasseur L said he had oncetried measuringthe maximumvolume of pollock being caught In trawls and the problem of interpreting the evident salmonstcmachs by pouring mercuryin them, but that they alwaysdistended cannibalism. and subsequently exploded before they got full; their studies did show that the maximumstomach fullness of chumsalmon In the wild was6$ to Word also mentioned the superiority of Keen and Coen's ukey to the geuerau for ident I fylng small pelectpods, ?$, whI Ie experlmentaI laboratory feeding situations wenten as h I g h as 14 t o 15$of bodyweight. CaI Ilet wonderedabout the useof subJectlve sca es, especially the problemsof "grey areas" with iona scales. Terry Primed by a coffee br eak, the part I cI pants entered into a I I vely discuss lan explainedthat of their sevenvalue fullness scales, only four wereused concerning the optimum level of taxonomic I dent If lcat ion of pr ny organisms, Word presented the view from the taxonom!st's angle, that prey should be very often and the others represented extreme cases not t yp cali ca y en- en- countered. Ident'If'led to species, In fact all the way to sex If the stage of digestion permits. H'Is argument was that there are. often distinct life history ar I-IerbertJaen icke said he hadused the volumetr c methodof Yenchersand ecological differences ln congenericsor betweenthe 9 and 0 of the same Herberts, measurlng zoopI anktondry weight over volumebut that It was species specifically citing amphipods and cumaceans>,which would imply t ime-consumingand prone to error becauseof the needto pooI samples, differential exposure to predation. He maintained that the prey should be taken ta that level and lumped back up according ta life history Information, S lbert simply asked If anyonehad done anything usefu w Ithe th percen t fullnu ness Index; I.e., whymeasure It? LaBrasseursuggesled that It and that One ShOuldn't "Slap SOmewherea'IOng the raute and Say, okay, thiS could be mareuseful ta record fullness as a percentageaf the fish's Is the most time-applicable approach to looking at stomachs," weight, Others questioned the feasibility of this time-consuming and expensive approac SteveObrebskl compared the subJect'Iveful nessIndex to that for percent as most of us are Involved In ecological rather than taxonomic studies. cover used by terrestrial ecolog Ists, saying that It had been shown Several suggested compromisesIn these analyses. Simenstad recommendeda two- that there weres Iqnlf cant differencesIn the estimate,depending upon t I ered system where subsaenples of representat I ve prey were retained after a the observer, producingan elementof error, He sugqestedthat It would detailed sorting counts and weights> procedure, to be ldentif I ed further by probably be wiser ta ga to same other method. a speclallst. Unfortunately, as several pointed out, quite often the specia- list never gets them, Stephens suggested going to species when possible Lauvastu reminded the group Nial the Abderhaldenseries I-' thr German according to the stage of digestion, as often as passible. This would then i aeidbookof Biolaq caI k ethads, whlch wnsproduced In Europeln the 9PO's require using the data In several ways, elimlnatinq data from certain kinds of analysis, especially since the precision of the data "simply dependson the! purpose of the analysis aeiyway."

96 97 Legrasseurwandered aboutthe cost of suchprsc I sion, est lniat lng that, given be to use cluster analysis to focus ef forts on maJor organisms In the a $25/hrspec laI st1 takilng40 hr persample, a 20 f lsh sump l ewould bring communI ty. the cost of $20,000per sample!Word replied that the s see everery thin ng, that a a severailstaaed sorting processguafantees Ihat the While /Illen Indicated that species which coexist in the softbottom demorsal comnunlt les tend to have dl fferenl' foraging behavior, Stephens ar

99

A PROGRAI4FORSTANDAROIZ INGTHE IDENT IFiCAT ION OF I4ARINE INVERTEBRATES

Jack Q. Word SouthernCalifornia Coastal WaterResearch Project El Segundo, CA Aroundwastewater discharge sites ihe typesof organisms,their population sizes andtheir d striI butlanai patterns are beingused to determinethe ex- ient of changein the environment Smith and Green, 1976>. In l973, the CoastalWater Project examined the ecologyof the SouthernCalifornia Bight, particularlyemphasizing alterations In the kindsof animalsliving around thesedischarge sites. It wasthought that comparativeanalysis of these datawould provide valuable information, lt waslater determined,however, that not all of the changesobserved ln speciescomposition were actually dueto environmentalchanges; Instead, some reflected Inconsistenlnr In- accurateIdentlficatlons of someof the over4,000 pecles of Invertebrates In southernCalifornia. Wordand Charwat, 1974; Word, 1975; Word, et al., 1976!. In order to correct this problem and increase the value of these dala, started the Taxonomic Standardization Program to facilitate the exi.liange of taxonomic Information and promote uniform identlficatlon amongl50 practic- Ing southern California taxonomlsts, This programstandardizes the level of Identification and the name-used foI eachparticular speciesthrough a series of publications andworkshops with various taxonomic experts. Workshopsare typically scheduled every 2 months at which presentations are madeand keys are distributed among30-40 par- ticipants. After the formal presenfationsthe group of organismsunder dis- cussion are looked at in the laboratory and the keys critically examined. information presented during the workshops, Including the keys, any modifica- tions to them, and new taxonomic information are then published in the bl- thiY~P* di ~ iih i i Si d di ti i~ hl t i *iid to over 200 participants in the program, The proceedings are meant to be stimulants for interest In a particular group of animals and hopefully the Interest created wi I I result In commentsabout particularly dl f f1cul f cnup- lets In the keys or specimenswhich do not fit the keys. Theyare addition- ally intendedto provide up-to-date, accurate taxonomicinformation,

Contribution Number 7R, Southern California Coaslal Watnr Research Project IO3 pal.semenritteri Holmes,1B95 CommasName - No omman c name in use. Anoutgrowth of the Proceedingsis our I inaldocument on i danii f ication of speciesgraups, The invertebrates of SouthernCallforrfia Coastal Waters Word andCharwat, 1975, '1976!. Thesevolumes Include ail the necfssaryInforma- tion Ieg. flrgures,keys, glossaries,etc.> requiredby the non-experttax- onomistto quilcklyand accurately identify specimens af the «peclescontained In eachbook. All 'Informationon eachspecies has beenconfined to a single page,contained in a looseleafbinder IFIgure Ia and Ib>. This will allow us ia revise, add, or delete species fram the volumes withaui r eqult Ing a complete revision of the publication. Webelieve that the main reason for the successof this programhas beenour d!rect interactionwith the sc'lentistsdaing the identifications, Byusing the knowledgeaccumulated by these scientists and thrauqh its sharlnq af the workshopsall of theactive participants ln the programhave Improved their Identification abilities and increasedtheir efficiency. Manyof the s stematlcproblems recognized In past yearshave been corrected affd the analy emys Is andcamper i son of datacol lecteci by the manydi f ferentorganlzat I onsn In southern Cali farnl a Is becoming feasible.

L ITERATIJREC ITED

Smith, Robert W. and Charles S. Greene, 1976, Biological communities near submarine outfall. Journal Water Pollutlan Control Federation, Vol 48, Mo. 8, Aug. 1976 pp. 1894-1912. additional DiagnosticCharacters: Southern Cai I fornfa Coastal Water Research Project. 1973. The ecology of Color: Translucentwhiter egqswhen the Southern California Bight: Impl'Ications for water quality management. presentare pinkish in color TR l04, March 1973, 531 pp. Size Rane: upto 4 cmin t otal len th Ward Jack 0 197w Invertebrate taxonomy program Southern Calffarnia H bitat: lffcommon rocky intert.idal and Caastai Water ResearchProject, AnnualReport 1975, pp. 67-66. a 'brackish water inhabitant. o f bath coasts of Saga Calrfarnra. Word, Jack 0., Brad L. Myers, LesI 'le H. HarrIs. 1976, TaxonomicStandard- It has been found in southern i zation Program. SouthernCa I i for ni a Coastal Water ResearchProgram. CalifOrnia at San DiegO Bay. Annual Report 1976, pp . Ig5 196. Y ~ 1 '1 PP ,* fin Word, Jack 0, and Danuta K. Charwat. 1974. Taxonomic standardization. 1 ily P,pp 1Yi.d ~ . P a Southern Califarnfa Coastal Water Research Project. Annual Report 1974, of. the family Hippolytidae have pp. 53-57. tsultisegrsentedcarpi on the 2nd walking leg. Word,Jack 0. and DanutaK. Charwateds. 1975. Invertebrates af Southern California coastal waters I. select groups of annelids, arthrapads, Miscellaneous Bapyrrd »op ad p arasites echlnaderms, and molluscs. Southern California Coastal Water Research are commonlyfound under the Project, August 1975. carapacenear the branchiai chamber. Word, Jack 0. and DanutaK. Charwat, 1976. Invertebrates of Southern California coastal wafers ll. Natantia. Southern California Coastal Water Research Project, May 1976, 238 pp,

Figure la. Samplespec i essheet s e fromkeys ta invertebratesnl SouthernCalifornia caastaiwaters

104 105 itt ' 1 * ~ legS

SYNONYffS Leander ritteri Nahili 1901, Nan pelae eemonritterr? Rethbun 1910, oi Schmitt l939. D ISTR IB a TION RANGE:Fram San Diega, Calif. tO Magda- lena Bey,and f.n the Gulf of Calif to Guaymue Fram intertidal ta 30 m From Halmee I&95: Sen Diegox California. F REqUFIVCYQUFIVCYDISTRIBUTIONS OFFOOD ITEM COUNTS IN INDIVIDUAL FISH STOMACHS ram Rathbun 1904: San Bertolame B d Magdalene Bay, Baja Californi La Paz Harbor, Gulf of Catifarnra Slbert rom authara ' data. Algadanez ayl Gueymua, Sonara, ffexiea intertidal Departmentof the Environment,Fisheries and Marine Service zone!. Paclf'lc Biological Station, Nanaimo, B.C. Obrebskl University of the Pacific, Pacific MarineStation, Dillon Beach, CA

Stcmachcontents analyses are conductedfor manyreasons, The results of suchstudies are usually statementsabout the suite ot food Itemsconsumed by fish andstatements about the amountof a particularfood Item consumed bya particularspecies of fish In relationto anotherspecies oi fish or latlon to the samespecies, taken in a different sample. Thestate- mentsabout rangeof food Items preferred are rarely, If ever, pr esented in a simple,clear, quantitativefashion. Similariythe statementsconcerning t f ti ular food item are rarely accompaniedby tha additlon- al lnformat!onrequired to evaluatethe sIgnificanceof anyobserved r vad dld f- ferences. These ese observat'lans are not necessarily Intendedas critic sms but rather should be taken as commentsand reflections on the compex y of the problem. In this paper,we report someprelim'Inary results of workin progresson the variatlan of stomachItem counts betweenIndividual stamachs. Thepurpose is three f oId: : I! t o" ge t a feel" for the range af variation In a rather d of data 2I to search for a methodof representingthe central tendencyand dispersion for stomachcontents data; 3! to explorer the statis- specimen tlcal propertiesof the data prior to the applicationof multivariate number la pi 0301004001 pattern-recogn Itlon on techniques. Wedo not proposeany definitive solutions ta the problem,but wemay indicate somepromising avenues or ur or Inquiry.

Methods Thedata cons1 stof the resuIts of the d ssectI i onand anal ys Is of approx.i- matey 17,000fish stomachscollected from 7 estuarineareas an the Slrait of G eorg Ia. a. The e i fish species involved are principally juvenile saimanid,, herring, stickleback c e perch and sculplns. Thesedata warecol lec e< 106

107 usedfor thepreparation of environmental Impact statement I I ti pro p osed d evelopmentsv In the Frasei,Nanaimo, Campbell and sC n I reh a on to estuaries Goodmanand Vr e an ow c an River study beginsa secondmanand

Results

stomachsThefinal aredata summsubset r' < onsists of 1,712 fish stomactis. Thecontentscon en s ofof theseth dlfferen a izedIn Table3. Iliereare evident -Iml Ia r't i ies an d erences.but the significanceof someof thee erences differenc Is Impossible o evauae romthe data presented, excepton the basis ofIntuition. FigureI. Mapstations ofthe Nanalmo Riverestuary showing sampling Thecharacteristics of the .One of thebest-known contagious distributions s r u ons is s theth

I D9

108 4IO DO oaa JJODD OD -o oooo«I«oa ~ ~ '0 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ O' 0 0 0 D 0 0 ln 0 D IPI0 « ~O IPIO 0 O' 0 CO0 4 lrl Irl VI 10 cu AI

Table I. List of fish sper Ies included In the data set aacoaar DDDAJDDr Daaaa Herr ilng ppl~ul ~ 0 ~ ~ ~ ~ ~ ~ ~ ~ 0 ~ 0 ~~ ~ 0 ~ ~ ~ Chum salmon 0 0 0 D 0 co~ OOOO«ODDOO ~ DOWlJJf«c«i Chinook salmon Coho Salimn Thrcesp inc st ickleback Shiner perch car ov D O LACO CO Ln PA ccl cl 0 O O~ ~ ~ o ~ ~ ~ ~ Prickly sculpin IA uI «7I AJ0 o 0 «0 cr ««0 0 0 0 0 IJl«0ui Irle Pacific staghorn sculpin o IO Al

Table 2, Ranking of food Item by count, bilomass and Incidence Dr D«ooruonloa oooo Ipl0 0 AJ0~ LJ ~ ~ ~ 92 ~ 0 ~ ~ ~ ~ ~ ~ ~ ~ 0 ~ C DD0AI O 0 «O«27 0 0 0 0 ru 0 0 0 0D COD IA RANK ce 4 «Al O' IO Cate or Count B Ioir«a ss Incidence

I. Harpactlcold copepods I rhlD « IO«co 4I ««PP«co «PPIAJ D 0 0 o 0 0 92 ~ 0 t ~ ~ ~ 0 ~ ~ ~ ~ 2. I I I 10~1k 2I 3 5 ~ ~ ~ ~ ~ r 0 ~ S oac7cn 3, Unidentified egg J: CODD«rhrI 00 «76rhm«q-OO 0 coO' 68 5 142 ««7 4. Anlso ammarus spp. 8 5. 01 6 5 103 ID 6. C~LI p p. 0 D D 7. ~«h I l. 111 109 «7 4« l el«aine m«uoDDJ «ocu ~ e ~ ~ CL 105 6 19 ~ ~ ~ 0 ~ ~ ~ ~ ~ ~ 0 ~ ~ ~ 0 LAID E0J 8, Shrimp larvae 15 'u COO' «7tu 0 AJ0 ««0 0 0 0 IA «0 ul «D JJ Lh 9. Ch lronomld '!arvae Jp ~ PlW 14 7 9 7 Ch VI 10, Zoea II 192 Irl II. Herring larvae 29 8 L I 12. Unidentified fish coa oo PV Ail «0 Lnrpl a JJ 0 «pn pnppl 0 Iph ~ ~ ~ ~ Lo «J larvae 26 3 g 0 ~ ~ ~ e ~ ~ ~ ~ ~ '0 ~ ~ ~ 0 0 AJAJ 124 IA o 0 0 ~ clap 000000«000 «a I 13. Oiptera IR 20 D AI 14. Cur sp. 7 IQ 15 206 Eo IS. Cyrp s 26 + 16. ~C* h p. 15 137 9 20 0 CCtCO 0 Vl O 0 0 O 5 17. Pseudocalanus minutus 18 J«COO O'0 o o ul o' o r o ~ ~ ~ e ~ ~ ~ ~ ~ 23 Jc ~ 0 o ~ ~ 0' ~ ~ ~ ~ ~ ~ 0 0 «0 0 Al ul I 0 0 18. Fish egg 27 14 16 Al Al co O 0 0 0 ih 0 rpI 0 0 JI ul 19. Centro a es abdomlnalls 12 21 Al Al 0 29 +. 20. 0 I h 23 22 14 V7 Irl crl «0 «JJ o o. z 4 ~ Z E0 u Q0 Q 0 Z caz z 0 Q ~ cn LJ uJ «/I Q o. « I-5 4 crp«EZ Q 0 Irl A u. X 4 «Q LO ~ OO. 0L Vl O. 6 O Qvvo. < Q ILJ 7- 7 I/I cVI«0 e 7 I'~ 2Crl O. ChPJ CC ILI IJ LI I VCl I' J JL «L LLj Il l -7 I I I ~ COILJui2 6 oIl o ll & o M 2 LJ«L LP I I- «s- ca Lrp«vl G COI- WLJZQ Q 05 VpW ;I" Q C3>- Iki .. Z 'W«c «LD a LJ w o z a. 0«eQ ~ 7 Z IA 0 2 7 e Il O «DIPPY 0 C>X mh«Y Q IP,LP LJ A ra « z «Q 92c«o w E o 0 ci SzzA.Q>~X QWMWO LJ g J- Q 0CLJ LJW Cl X. D I I 0 prickly Stag. Herr, Chum Stickl. Chin, Shiner Coho sculp. sculp.

009 Harpac. . 076* . 138 . 139 .021* . 062* . 011 . 103 I Tunicate .022+ .065* .034* 499 I I'H«tt 7 egg . 016* .014* .017 00 Anisogam. . 114 .096 .096 .080 . 100 .069 .860 .552* I'HIIV C. Slee. .023 .044 .023 .027 Ccroph. .067 .095 ,067 . 099* .024 1.004 .533 g. pac. ,032 ,031 .025* .026 I shr tlap l. .061 .D45 .030% .027 V P Chir. 1, ,028 .059 .Ol.3 ,021 .D12 .079 .099 0 I ~IN tl tP~ Zoea . 085 .06109 .085 .023 .016 .018 t- Herr. l. . 012 . 017 .060 .131 P IP TH«00IP 8 Pt II.F. L. .044 .023 .073 TtI tPt' ' ~0 Diptera .177 .066 .083 .029 Euryt. . 011 .Dl7 .025 CypEis. . 106 .OS4 .120 .054 .011 .059 r 9 2 gxos ph. .015 .024* .033 .323 .214 TOT.II CIOVPCHI to 0 I 2 9 T D 9 P. mistutua ~ 015 .010s .027 HPDPPCTICDID'9 I 9 TO«PEN[ IIV Fish egg .088 .071 .068 Cent. .011 .010 Parath. .082 .OSS .035* tto. of 267 402 302 184 285 106 116 50 9tt4 stomachs 009 90 Ertc«CC9~ CH 9TIC«LEDP C« >0

Table 4. Values of the patameter of the negative b Inomlal dist rlbutlon. Asterisks PI Z 'Indicate cases where departure from expected ls significant at the TO «920 0~ O P <.05 level by a Chl-squared test for goodness of fit. I3ianks occur O92 where there were Insufflclent data ~ 000i9 '~ 00 0HP lbll TP 4 0 rl 0 0 204' 10 ~V ~' 00 O r« 0 00200 IEIO I 42' 220

f 0 I 2 2 ~ 9 9 I ~ 9 ~ 9 2, T 9 9-22 COPOPHIIVr9'IONPC" I'ID I Q 92IlIPPCTICOID'9 I 9TOVPCH I~ tD I

Figure2. I-llstogramsof the frequencyof counu t s In Individual fish stomachs

112 TheChil-squared statistics on the hlstograms Fig. 2! Indicatethe goodness of f It of ths datato the NBD.Table 4 containsmaxilmum I lkel ihood estimates Bliss anf Fisher, 1953!,of the parameterk of the NBD,The agreement of the datawilth the NBDseems generally good, although not as goodas onewould Iiks for certain keycombinations of fish andfood species eg. harpactlcoldsln shiner perch and chinook salmon!, Oneof the desirable properties of the NBDis that two other well-knownfre- quencydlstrilbutlons can be derived as limiting casesof the NBD Fisher et al. 1943!. In particular, If the parmeterk ils zero, the limiting caseIs Fisher's logarithmic series distribution LSD!. It can be seen from Table 4 that most valuesof k ar'erather low, suggestilnq that the LSDwould more ac..curately rep- EVALUATIONQFOF STANSTAND!NGSTOCKS OF MARINERESOURCES IN TIIE EASIERNBERING SEA; resent the data. Thils dfstribuiton has been widely used to describe the USINGA STATIC-TRQPHICNUMERICAL BULK BIOMASSMODEL BBM distribution of individuals in speciesand fts parametershave been shown to behaveIn sucha wayas to suggestreasonable biological Interpretations, Williams' 1964!. Hopefullywe can have the samesuccess In this application, T. Laevastu and F. Favorite National Marine F I s hsr I es Ssrv I ce Northwest and Alaska 1 'Isher les Center Seattle, WA Conclusions

The usual methodof summarizinga set of data Is to c.alculate the mean I.s. ABSTRACT% arithmetic average>and ths variance i.e, meansquared deviation! and these twostatlstilcs canbe shownto containas muchilnformatlan as the original St an dl ng stock size of any marine ecologl g raup I s de p endent, recru It men t on ecosystem internal cansumptlon an growth, and on mortality data provided certain assumptions about the data are satisfflsd. In this tes. Growth-rate data are generally avaflabie, as are flshin ' g and natural case, these two statistics are woefully 'Inadequate. The bars on the hfsto- ystem internal consumption can be deter- gramsIndicate the meanand 99$confidence 'limits. If the samplesize were it rate estimates. e ecos smaller, one caufd accept a hypothssilsof zero msarr,which Is clearly a mis- mnemined b yfood requireme~ts for growth an d for o maintenance! and composition of food of all componentst f o e the marinema ecosystem. A static-traph1c numer- representationn of the data. Clearly, a better way to summarizethis kind of onsum I ir;n I data mustbe found. Thesedata are not normally distributed and no reason- Ical Buik BIomass Mod e I that computes the ecosystem interne I consumirl ir;n s prograrrrrred and uses an Iterative techni que to derl ve pi aus ibl e standing able transformation can makethem so. The solution will probably !Ie fn the ca I rou s, using growth anr mor a i y properties of some other dist "lhutlon function. Modelcomputations indicate that the availabilityi abl'Iit oof oo food 'Is s e the mainm,' factor Iim Itl ng th e size of standing stocks of most ecological groups above herb- ition of LITERATURECITED Ivorss; the need f arf ur th er research on faod coef f iclents, comprs food, and feeding habits Is emphasized. Bliss, C. I. and R.A. Fisher. 1953, Ffttlng the negative blotomiac Model results ind I cat s a th t; ; on I ! anl y a smaI I fract ion of the annuaI piryto- distribution to biological dale. Biometrics 9:176-200. e a Ic Plankton productfon s used directly by herbivorouszooplankton arrd pe g EnvironmentCanada. 1974. An environmental assessmentof NanafmoPort fish <10$!, and theh bulk u o of this production must go to a rsgsnsrel ion cycle alternatives. Lands Directorate. orsn Ink to o e the bottom o where It ls consumed as detritus b ybenthos en os Table I!; EnvironmentCanada. 1975, Fisheries resourcesand food webcomponents of 2! the estimated consumption of zooplankton Is s considerably higher than the the Fraser River estuary andan assessmentof the Impactsof the pro- standing stock and pro d ucti an as ascertained from avail able data! woul d permit, Indlcaatln ng that a s the pr resent quantitative zooplanktonon data are de- e- posed expansion of tire Vancouver International Airport and other n in the sea; and 3! there must be developments on these resources. FIIMS f'clsntIc and/or starvatlon is rather corrmron n s sea; considerable standing stocks of squids anand smsmal I elagic p fish Pacl f ic Fisher, R.A., A.S. Corbet and C.B, Williams. 1943. The reiaticn betweenthe herring, Ctrrpea rrarerrgrzapa f.laei ei; capel in, /rfaf fetus vi l Tosue; smelt,It famll am y numberof sprcies and the nuruirerof individuals in a random sample of an animal population. J. Anim Ecol, 12r42-58. te a er b Lasvastu and Favorite is too lonq far reproduction in Goodman,D. and P,R. Vraom. 1974, An assessmentof the fmpnct nf proposed the proces ngs. ct with I fi urs and table are marinadevelopment on the fi"heries resourceson the C,rrnpr.eliRiver m lets a er has been r eproduced as a Northwest nnd estuary. Environmsnl Carraria, F&MS, Tech. Rep. PAC/I -14-13. p s ~ o p p p Alaska Fisheries Center Processed Report and Is availa s y wr nq WI iIi vms,C.B, 19<4.Pal I ri ri~ i. r>ihu Ira I:mr n ain rfrrr r.. fr >rlrrrrl r. I're"' .324 pp. authors.

114 115 OsmelI idee; etc. ! In theBer Ing Sea 1>3.5 ton/km and ca 6 ton/ uponthem. s y e oodrequirements for other ecolog'Ica I ggr oups graz I ng

Plausible standln BerlnSea are g stocksof variousecological groups Inn e th eas t em coefficients9 presented, of the fish In general,It canbe postulafed uae that a cfoodth fishIs more efficient e s In food bothutillzatlon!for growth andthan maintenance! assumed heretoforearelo~er and !.e,, thata considerablepart of thebiomass of fish Is I r which have hl g h th coefficients.o sngrowJuveniles sFigurerecruilmentI,Schematicfcod fdiagram for BBMmodellow

maJor contribution --- ---minor contrl but ion

117

116 Table t. Annual meancansumptlons, siandlng stocks, and rne A STORAGE/RETRIEVAL/PROCESSING SYSTEM FOR STOMACH ANALYSIS turnover rales kg/km2! In EasternBering Sea as AfID OTHERFtSH DATA with SBMmadel!

Ciarles A. Slmenstad and L~rry FisheriesResearch Institute, Universityof Washinqton !faathly Ann Seattle, WA Ecological group standing stock cons urs Elaborate,ecosystem-wide env'Iranmental surveys generate a profusion of blo- Phytoplankton ,000!~ l.OOF000 36 I h b h ndledonly by computers.Such large databsses lo Ical data which am canIex e when an they e deal with the In-depthexamination of the Zooplankton 00!+ 20 000 Interactionsp r between y p components of various troph c eve s an r copepods, euphausids ! shipto thedriving variables and nutrient Inputs responsible fortheir e. This is certainly the casewith foodhabits studieswhere the Megaloplankton 3,800 maintenance.d'Ietof an Individual h s s cerpredator a n can be relatedto I ! ph ysicsical and chemlca'I squids, etc.! I ment 2! temporaland spatial aspectsof predation, pa rarne f e rs I n theI f env ranme th n uild or communityof whichthe predaforis a part SnraU. pelagic A.sh 8,200 12 4!3! theth compositioncornosit'lon oand e abundance gu of the availableie prey re communltcommuny, , andan 5! the herring, etc.! e compos f Ifi s andcohorts. In thesecircumstances t bilithe a ' y prey spectra o conspec c to interpret a speciesi ' o bserve d diet dependsupon the efficient retrieve'I of Large pelagic Fish T60 datasubsets frcm a large,diverse data base and subsequent Input into a salmon, etc. ! processing system. Benthos 200,000 25 wouldlike to describebriefly a datamanipulation system presently being t Fl h I Researchinstitute at the Universityof Washington, predatory benthos! 0 000+ 48 developed a si d er t h es die data fram an extensive surveyof nearshr!~e which i s des gne Itl a an I rthern Puget Sound,including multi species f oad ROundpi sh marine fish corsnun es n no 9,800 habits information. Flat fish 4,700 Objectives af the System Others 14 The data manlpu I ati on an d processingsystem, called SSRP,Is designedta facilitate: 1/ All exclude Fishery 1. Screeningof the data for unacceptablevariable values 2/ Standing crop/consumption excluding Mshery! 3/ mg/m3 7. Sortingaf fish data

118 119 4. Interfacing of these dale subsers with processing prograpns providing thesort keys th directoryserve as pointers to otherda ta blocks statistical summarization I i f t randomretrievals and slow serial re- n the data base. By combn ng as '5. Input of the sunmfary values inta programmed plotting rout Ines. trlevals, onecan economically extinct almostan y smal I data subset 1

Indirect retrieval functions are a composite of random and serla! functions and operate as follows. First, a random function ls used ta extract a small LITERATUREC ITED data block, called a directory, from the data base. The directory contains 1971, UPDATEReference Nanua I . ContraI Oafa non-sort key variables specifying callection and environmental Information, Contro'I Data Corporation, In addit'lan to the sort keys. Then a serial function which may operate on CorporationTechnical Pub'Iicatlans Department. any variable Is applied ta the directory to obtain a subset of the directory, 75. RIRS:a randomizedInformation retrieval system. ca'lied the sub-directory. The subset of sort key values which occur In the Gales, L. E, 19 sub-directory then guides a random retrieval function which extracts all Universityof WashingtonNORFISH Report Nl 39. , p. 14 data blocks from the data base whose sort keys match a portion of this subset. University of Washinghl t on.. 1973,SIMPLOT User's Manual University ol Washington ComputerCenter Document W 00071,56 p.

121 120 I !, SSRPSTSTEM STRUCTURE 4LI J LIPJ.'I Idl L>uu' a 1, I'I XYV' L LLJ VIYLCwu u c 7 0 0 u 0 0 i» v lf 'u 0 a Lcl 0'I I I 0 uu 0 ce'C Zz4n 4ace uu ~z fdoacc ~ 4ccuucc cl: ~I ~ I ie CCC 401 VvLLn au' JQ 0 'I v 0 0I I'0 I I I I I I~ I I I I I I I I I I I I I I 01 [--4 II V I 4 fl 4 4 rl 0 0' I I I OO I a 4 4 4 I ~ a a LJLJ 0 C 0 II I t fd LICcu vaa w w,aCaI C0 r.ciu w I L 0 0 I ~aL a0 aI 0.frau Oa a I OO .:"4; I92 I Wul4 u ~ 'ed vvica I I lu.ad I I Y tI 0I 0C cduzzdzaad coccddoc=a. uz Ir coa add

I I Z 0 0 4 I I I- '0 I 1-92- 0 I- I 4 4 4 4 4 4 4 ~I 4 4 4 V4 1 Z IO lut 0 I 4 4 4 OC4 4 4 4 QCI I mZt Z 0 I , V'vppvvv vv v 4Juccco ldlvuVIWLJY Juoccouulvull LJldW I VCt atDOcul OdlOOLIOQIC ~ O. I Z Z it C 0V 4 E OI I I I I ull0 0 1 i I I o 3 iII 0 ~ 4 0lJ I' IwWala 4WX 4 L 4IL092 Yvu ~Lwwn 4 YJ Lol-IQQI-P zzuud4v CCZ* plea Z Pt 'LI0 u u I 0 VJvl c 0 'z Z 0 0 X 0 4 4 0 0 0 V iooV14 OcluJuana tlnltalauuaa 0 VIXX 0 ' J J JQJa 4Q i I ~ I ~ tWI w44XXcoz 0I I4 I XI C I IC 41 I 92 492 4 0II I0 ltI 920 uI IL.' 4I Iu 4 I I4 I I I I I u I I 4 o0' e 0 IpV 4 4 NIL0', 0' lr fv tv 0a 4 4 4 I I tl, 0.0 J I~ I I IZ~ I VlI I L 0 4 I pv'v pu'u'll'upu v'4'v' I ' I ++I I I f I I I I Pl [ ~.I [ ~.I I I I 'I ! IVX I 000 0'lf O'lf 0'0'0 r'0' 0 0'0 0 O'0 0'O 0' O. 0 O 0C I 44 4 4 4 IJVl It o I filler NNaa 4 r4 4p,aaaaN!L 4 I 4 4 4 a N 0 Z ~ I Nf4fu I 01IV NIV X.I 0tr ~ ~ Z 0,'I IZ ~ ~ ' Il 0 0 C C fuIV IIIV' 41 t a a 0 4 ItII IIII I 0 I 0 ~ I- ul I 0'QCLoDCOCowotuaaaaaau aaoe 0 ~ f.v ptf V oo u Iro o LP Ifo Ira If4If 4'p v Irv Ip0 II v 0 If v 0 v I- t IJ I I I XoID uW ~ ~ CX J ~ 0 O. ~ C

123 Figure l. Oyerai I sfruoture eftd operetlon of the system

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fj29 Sibert replied, "Distr ibutions are similar except that the effects of lumpingdata g 1vemore zeros and high numbers, I f you reducesamp1 o size, It sti I I retains the general shape. If you lookedat a thousand f ish, al I cal lected on the sameday at the samelocat ion at the same f ime,you wouldstl I I f ind a positively skeweddistribution.n pbrebskl remindedthe group that mostdistributions of benthic organisms look skewedand that is one reasona negative binomial is a widely used distribution. The usual procedure is to normalize the data «ith the Iogtransfarmatlon and use the log-transformeddata, keepinqin mind that the log of zero doesn't exist and lt is necessaryto add I lo each numberbefore transforming 'lt. Slbert reinforced his earlier thoughts DISCUSSION:SESSION 4; DATAf4ANIRJLATION by slating, "You'd be better off lo use statistics appropriate to that AND PRESENTATION particular distribution or usea non-parametricmethod." JohnStephens asked, "For example,could one use the slope of the curve Respondingto questionsabout the newSouthern rn Cal lforn orn la Coastal Water Research Project SCCWRP!taxancmic k of the frequency d'Istr lbut ion?" Sibert suggested that sometwo-par mneter axancmic keys, Jack Word explailned that formuiae could be used to descrIbe such a curve. Stephens then asked, alth oug h th e keys emphasizep southern the so Gali fornia groups, the SCCWRP staff is addi uWhywould a benthic population necessarily approximalethat particular s a s adding northern Cal 1fornla groups and I sI nc I udln onl rel lab le I iterature references. He said that th g frequencydlstrlbutlon7n Obrebskirepl ied "Becausethe organismsar.e d d s up h group, e.g., Volume2 Shrimp! Includes lnter- patchlly distributed and,when you sample for patchydiistributions, some eet In depth, Including midwatershrimp. Threeof the 2 sampI es have very few organismsand other sampleshave a large numberot project peopleare Involved In taxonom'Icstudies--not a h1 h erc organisms.The variance af the distribution is the sumof the deviations As to subsequent volumes Word h h from the mean, Whenyau have high patchiness, then that variance is high or says he has: andyou havea situation wherethe variance ts very high In proportion to an ophlurold key 6 species! completed, the mean." Although this Is from the point of view of communitysamp!Ing, "usually the samplingd'Istrlbutlon reflects the actual dlstribut1on of organismsIn space," If the organismsare distributed at randem,some a mlcrocrustacea din u been used, for Instance, by Lloyd In an article on something called th k ho I th fl t t o k "meancrowding" which was in the Journal of Animal Ecology in 1967--ro rleal with the problem of describing the patchIness of organisms in n pu s ing ls Increasingand appears feasible at this time. space. Obrebsklpointed out that the underlyingdistribution In this During a discussion of the Im Ilca patchInesssif'uatlon wasthe negative binomial. Overall, the patchy CaI I I I et mp cat lons of a lot of zeros In data, Grereg character of most sampling situations Is something that people should be e asked of John S'Ibert whether, evenn ougthou h th e mean of a group of numbers Is a measur f t aware of because It detracts from the procedure of estimation which they' re ure o cen ral tendency, lsn't It stlls a I fact that, if In a skewed array of dataa a, th e mean is a tot less because f using. zeros'? Callllet further asked If It didn'tn t ststill reflect that In a lot of guts studied there were not v GregCal I I iet suggestedthat indlvlduaI stomachconi.ents are not adequate ere were not very manyanimal s7 5ibert re p Ie led th a t samplersof prey Items. Perhapsone wayto overcometh Is wouldbe to th e median is simply half the dlstas ance n a total ran g ed an doesn t have any meaning, Steve Obrebski su pool guts, say ln 5-gut intervals, so that the chanceof havingone uggested normalizing transformatlons frequencyclass dominatethe data wouldbe less. Si Siimenstadobserved a o at nature but indicated that skewedewe distribution and large numbers of zer os s tillcreate problems, that It would be Intr lgu'Ing to measureovera I I prey distributions on the basis of an entilre fish school, I.e., C matc aster sp. or Juvenile BobFeller askedSibert, "Are distributions of a lar e chum salmon, compared to individuals passing hrough the same prey geo o « oe community. Callilet agreed and also suggested that if one did that, It erent than from 4-to 5-month pooled data7" might be possible to use parametricstatistics andmeasure central

130 131 tendency to see If ranklngs were slmiifar. of t fmebvt the overaI I diet compositionsremain bas Ical I ythe same.Ile Gary Smith noted that the problem of comparing s igni f leant dl f ferences dfd examinesummer-winter differences In whltefish diets andfound, nrrt fn propart'lons Is muchmare easi ly handled; f.e., the occurrences or surprisingly, slgnff fcant differences there. nanoccurrencesaf food items In the stomachsovghf ta fol low a binomial probablI ity dfstrlbutfon. Thenone can look vp the corrfldence Intervals Obrebskinoted that severalpapers by RogerGreen In Ec~olo dacurnerrted graphlcaI Iy, Graphicdeterminations can a Isobe usedta determinethe the useof the discriminate function In ecalogica I appI icat lons, I.e., samplesize required Pomeet proportion I fmlts whenone has predetermined effact of temporaI changes In environmentalvar labl es that affeet the precfslon objectives. structure of biafog Ical conmrunlties. Jack Word asked Jahr! Eliison wlrether he showedthat the two fish des- Ell'isonsaid that he Is nowInvolved In a project rgatherlngdata frown cribed In hfs studywere feeding differently. El Isanreplied that, f

132 133 lower limits Indicate d that a e the wholew conr>iunltychanges when fish moved all agreed thai the measures of diet composition to a large extent de- d d th conmionItems of 77 total species, e po yc a. pend upon the question being asked, If ane is Inquiring about the In and grazed own s coiimi selectiveness af the predator, it is necessary to know the size and specieswere preferred!. number of Items; If It's the "Importance" of a prey I am, you need a d th t f I h stomachcould be treated I ike any select lvn comblnat Ion of numbers, volume and frequeiicy of occurrence; and ff it' s Al lenler--trawl, suggested grab,tha aetc. s ssuch om that a lot of thesame community regarding the nutritional or troph'Ic role of a prey item, biomass se I d t th data, CalI Iiet pointedout ih,il this and/or caIarlc values are required. Calli Iel painted out that many ct I what H tub I di d I the ~Eco1o974! pap dis Ion of these parameters are alI combined in the Index nf Relative Importance d that each 'Indivlduai stomachwas nar I.R,I.!. of lizard food habits. He assume a e ch wauI d ria1 a random samplI eb u t y a very seselect sample;an Individual stomachwould ria have all the prey It ems, buf u when stomachswere pooled, there was a Returning 'to the quest lan af the appl lcabi I I ly of the I rophlc madel h th I d tomachswould represent the total assamembia q e described by I aevastu, Sfelner mentioned tliat there ni e uiidarnsnta I pooint at wh'Ic e poo e s of prey thatt were were founfound In n sths populat1onas a wholeand at thar time problems associated with these types of models, that they are dynamic Id comparetwo species, two locations, etc., c., Caillietai i suggusied only as a thermostat on tlie wali Is dynamic. A fhermasrat has a fixed you cou camp n re assemblages, from rate and the energy going through ls modulated aroiind t hat, whereas, that this points out several waysof comparingp y presence/absencedata, whwhich c s is wwhat s a lat of the similarity indices biomass estimates are variant temporally and spatially such that, as use,to tha useof proportions. Aswe' ve seen'however,however Slbert's er s Steiner noted, "Even If your b Iomass estimates are right on the nose, th t b the ranksby proportionsaren't so realIstic. then you' re still not dealIng with dynamic terms because your 'system' lk illustrated a may e Caliiist went on to pointi t ou t that a lf we can get around the specific Is being driven by static Inputs, e.g., biomass values, qi owth co- t b Slb t and generatesome ranks, then wewe' Ill e be efficien'ts, etc.." Laevastu described details of how he thinks the prroblem brought ou y er able to compareranks k b y s I mI larltyar Indices that deal with relet lvs model compensates far temporal changes although there are some options h t nd our uss of rank correlation techniques. that would be difficult and expensive to handle, Iike considering proportions, and thus ex en our uss year classes of dominant species. As It Is now, it has taken 30 hours d th various stat istical techniquesappl i cableta on the CIX 6500 to run Just one cycle! rau t thenanal aut sls. ne Cal eI I1st questionedthe possibiI itles of usinga i diff t i dim Allen questioned the validity of always lumping prey Items according stwesndifferent predators, setting up one predator as the exexpec ected.s to taxonomic characters, which he saw as leading to many errors, d makln It an hi x N contingency. RabinLaBrasseur Instead' he praposed,i syslem of grouping predators according to re iicate ump samples, mentions d that a they were using Chf-squareto test r ep ca p morphological characters Indfcatlve of the predators' food hab'Its. Thus, If the t'irst wasthe sameas the last; ass t I turns our each p sip once you had the predator and the food items Identified to species, you tosample see was an e Independent one.Callllet said that a lotof similarity could sort out the prey organisms with appendages whicii indicate active havebeen used In taxonomicsiudies to comparean arrayof swi>rmers, burrowers, crawlers, etc.. Allen went on to suggest that If er i c rac ers In one speciesto another; pserha p s y ou could think you were to take this approach you might not need fo ildentify a prey eln re categories, Calliiet also noted t a organism to Its taxonomic limit; yau would look at the prey organism's of these In terms of be ng prey morphology as an indication of its activity in the environment. e wasa a er in Ecologyby Sale 975!, who lnc u e Eucl i dian distance which 'Is ththe sum umafa ths praport lan of a prey item in Cailliet cited another example, Brooks and Dodson's classification of t m'Inus the sumof the proportions'Iof that ItemIn anotlier capepods into size c'lasses and comparison of predator mouth size and redator! and derived significance 'levels to compsare p re y s pecles s'lze of copspods eaten. Obrebskl recounted his experience with the f f I h . WendyGabriel mentioned that Overton Brooks and Dodson data, He calculated the dfversity Indices! af composltlan In ree s ss. en ortions as , OSU!has dave'lopeda programtreating proportions ua'lewifedn and "alswltelessu lakes to test the hypothesis that selective Forest Ecology,th I f the angle betweenthe two vectors is a pt sdatlon would affect the plankton crmmiunIty by increasing diversity. vectors, ion where coeff elclent; cos ne Obrebskl o brought up the useof I4arasia s At that time no one had developed equations for calculating expecta- a matrix format BobFeller suggestedusing tions and variance for the Shannon-Wiener function so they cou/dn' t f the ardfnatlon classification tschn'Iques,0-mode an -moe, detect significant differences. Obrebskl found that 'ff you corrected sama o e a u h as Pools 974!, for 'lake size and depth which affect diversity!, lakes with alewlfes out li ne d ln n e the basic statistical ecology texts s c bskl noted the uss of the scaled Koimogarovs tai a istic which cari be did have higher diversities. Co'iln Levlngs told how he used mean we'Ights Obre s no e distr Ibutions but, given a large enougtisample of prey faund in flounder stomachs to generate frequency histograms of used to testI I size t el frequency wes shaw sdi r fferenl u on sign'II icanl f fgures. Caiiiieia i e numbers af organisms 1n specific weight categories. He compared size, will almas a ways s a ues i.e. S sarman and histogram curves for «hat was In the guts versus what was In the environ- askedd aba u t the useof rankcorrelation techniques, i., p ment grab samples! and found that It coincided during several months, Takfng it further, Levlngs discovered that cutting off t' he upper and

134 135 KendalI; Simenstad recommended thata ccmblnaf ionof rankcor relation and overlapIndices using Shannon-Wiener!, bothof whichhave establ ished testsof s Ignif icance, may be necessary to detect shl fi s ln preyorgenl sm rank and diversity of the prey spectre.

136 DIETOVERLAPS IN COMPETING F 'ISHPOPULAT IONS IN THE NANAIMOR'IVER ESTUARY

StevenObrebski, University of the Pacific, Pacific MarineStation Dillon Beach, CA JohnSlbert, Departmentof the Environment,Fisheries andMarine Service pacific Biological Station, Nanalmo,B.C. Anexpanding ecological theory concerning factors affecting the composition andstabilIty of natural communitiesexists seeMay, 1974; Cody and Diamond, 1975;Goodman, 1975 for recenf reviews! and a major goal of ecology Is to test its validity. For example,when sufficient Informationon resource utiiizatlon by competingspecies and resourceproduction is available, Ihe useof competition theory to pred'Ict speciesabundance Is feasible Pulliam, 1975!, lt Is of related practical Interest to knowthe degreeto which marinefish competefor food resources, For insfance, the stickleback is knownto be an Importantcompet'!tor for food of the sockeyesalmon Foersier, 1968!. Fish food habit studies might not only provide informailon for test- Ingecological theory but alsofor op1imlzlngfisheries management procedures If methodsfor m'Inimizingcompetitive food utllizatlon by other fish anden- hancinggrowth of exploitedfish populationscould be developed.Could selective removalof adult stlcklebark Improvegrowth rates of younqfinger- ling sockeyesalmon 'In lakesor Juvenilesalmon in estuaries'?With such Ideal longrange research goals In mindour purposeIn this paperis to out- line someof the problemsof measurIng food resourceover'Iap In co-occurring populationsof variousfish speciesln the NanaimoRiver Estuary on Vancouver Island, B.C,, In Canada. Samplesof 9 speciesof fish werecollected ln the NanaimoRiver Estuary In 1972-1974.Generally beachselnes wereused In shallow interf Idal areas andpurse seines ln subtidaiareas. Dataon diets of fish collectedevery 2 weeksbetween March and July, 1973are available. This information forms the basis of the present analysis. Details of samplingprocedures and Ident'Iflcatlon are available In Anonymous974!. The data Include 79 samplesof Individualfish specieswith countsand biomass measurements of qut contentsfor over 100diet species. Thetish sampledwere herring, spinest Ickieback,shiner perch, Pacific sand lance, prickly sculpin, I'acific staghornsculpin and Juvenile chum,chinook and cohosalmon. Thesampling stations are shownIn Sibert andObrebski these proceedinqsl. Four stations , 13, 14, and 15! were in deeperwater andwere sampled w'lfh

139 Leest squares fits to thedata graphed yielded correlation coeffilcients of a purse seine. The remainderwere Intertidal and weresampled by beachseine p,49for an exponentialregression and 0.68 for a powercurve, boihcoeff1- and pole ret at low tide. , cientsbeing highly significant p <0.001!. Wechose the powercurve to rep- resentthe relationshipbecause of the highercorrelation. The great amount Wewere interested in measurIng the amountof competition for food resourcesresour ef scatteraround the regressionshould also be noted. Onthe basisof this between the Juvenile salmon and the other 11sh species sampled. To estimate ~na ys Is weeliminated samples Involving fewer than 10 fish In comparisons diet overlap we used an index oi association due to I>iorislta 959!. The z>fdiet overlapto reducethe effectsof smallsample size In underrepresent- Index C Is wherex and y are measures ng th e numberof diet Items. Since the index usedis basedon the number 2 Px z items In commonwe wanted to decreasepotential variation in overlap due c> to variation In sample size. + gp Caiculat lansof CZfor f Ish col l ectedin the Wanalmo Ri ver Estuary are sum- marizedin TableI from whicha fewsingle speciespair results are omitted. of the propOrtionsof the I toed CategoryOr item IS speciesx end yy> ra- spect1vely. The data used wus the percent biomassof diet iter>s for all Inspecctlon on oof the table showsthat C varied from 0 to 0.99. Of particular items representedby 0, If or n>oreof total b1omassin a partlcul }r fish interest I s the recurrenceof very high Indexesof overlap betweenchum species. The Index C varies from 0 when there are nn food ite>ns in conn>on salmonand 3-spined st icklebackIndicating that at timesthese 2 specles io 1 when ail food Items are commonto both species and occur. In the same share are manmanyof their food Itemsand take them In slml I ar proportions as meas- proportions, d b food biomass. Wechose to focus on feeding relailonships bet~ace fhure 2y fish. Calculationsof C for all datesand localities for chum A serious problemtn any comparisonof diet overlap betweenany two species salmonese and st I ckI ebackwer e madeirrespective of samples Ize. Therresu ul ts results from the sensitivity of iten>abundance to the numberof specimens aresummarized ln Table 2. To test the potential effect of smalI sample from which the dial list is obtained. In Figure i we plotted ti>enumber of In reducingC we calculatedcorrelation cofflcients betweensample size diet Items in samplesof fish speciesagainst the number'of fish uponwhich ~ ze n the diet list wasbased. The results suggesteither an exponentialor power andCZ ln twoways. First, correlations between thesum of numbersof both curve retationshlp betweennumber of itemsobserved and Iisi> samplesize. speciesof fish andC werecomputed. Then, correlations between the number 20 f arer speciesand C weremade. The correlation coetficients were not slg- onif rare leant In bothcases, suggesting that sampI e size Is not a seriousproblem in this casealthough it shouldbe kept in mindthat a correlationcoefficient wouldhave to exceed0.5 to be slgnlf leant if basedon 14pairs of compari- sons. Inspectionof Table2 indicates that onehalf of the estimatesof overlapare 0.80or higher. Whilediet overlapbetween the 2 speciesis often very high, tempo~elvariations are often considerablealso. Varlatlons I C within spec'lessampled ln different localities are also evident. Chum cn salmonand stick leback In subtI daland lntert ldaI stat lonsare comparedfor c> the I- 15June 1973 sample In Table3, Whilechum and stickleback In sub- 10 tldal localities havean indexof overlapof 0.99, within speciesoverlaps for the 2 speciesfrom the different stationswere 0,13 and0.23, respect- IL ively! Theseconsiderable excurslons In diet overlapand variations within »I acies from dl f ferent local lt les suggestthat rap'Id andextensive changes nn specln feeding es behavior may be taking pieceover short periodsof time. The E K foregoinganalyses emphasize the needfor standardizationof sample size be- fore extensive surveysof feeding competition betweennatural fish popula- tions are made.Recurrent high valuesof CJstrongly suggest that the stlcklebackIs an Importantcompetitor for foodof the chumsalmon, but how reliable Is this measureas an Indicator of competitiont It mIght be con- 0 20 40 60 80 100 320 t40 jecturedthat If foodresources are not limited~ andif feedingefficiency In part densitydependent, mixed species groups might Increase feeding ffUMBKB OF f ISB f! efficiencyof both species. For Instance,mixed populations of chumand Figure i. Relationship between the number of Items observod In the diet of st!ckleback,feeding on benth'Icfaunas, might Increase food availability a sample of f1sh and the number of fish upon which the esiiimate of diet Item for bothspecies by Increasingd1sturbance of the substratesurface. Both number is based

140 141 TABLE 1 TABLEI CONTINUED!

DIET0VERLAP BETWEEN FISH SPECIES IN NAFIAII40 RIVER ESTUARY, B.C. IN 1-15 June 1.973 Subtidal Stations 'MAYTO JULY, 1973 Legend: 3SST-3-Spined Stickleback; CHIN- Chinook ; SHPE-Shiner 3SST CHIN COHO Perch;PAST- Pacific StaghornSculpin; PRSC- Prickly Scul fn; HERI- Herring;Morisita's measure CI is usedthroughout. No comparisons HRRI 43 0. 99 C.z4 are madewhere one oF a pair of fish is representedby less than 10 74 specimens; *! - 0.01Ca~0,001; **! - Cx

COHO PAST coHO 15 CHUM 18 0,81 0,81 0,02 0.12 16-'30 June 1973 Subtidal Stations 3SST 44 0, 0'3 0.97 0.12 3SST CHIN SHPE 26 0,04 0,13 HERI 100 0.07 0.12 0,18 COHO 0.13 CHUM 52 0. 80 PAST 26 3SST 70 88 1 -15 June 197'3 Intertidal Stations e e e vevv $$R s $4 sz ~

CHUM 0.21 0,05 TABLE 2 3SST 71 0,25 DIET OVERLAPBETWFW CHUM SALMON AHD 3-SP!NED STICKLERhCK cHIN 32 Data Intertidal Localities Subtidal Localities Runner 16-30 June 1973 Intertidal Stations C A CHUM '3SST cl CHIN SHPE PRSC PAST i-j 5 March 73 18 18 0.95 ISST 17 0. 35 0.>6 0,07 16-31 March 73 26 3 CHIN 13 0, 5'3 o,69 1-15 April 73 0.08 SHPE 13 0. 31 0.39 16-30 April 73 zi 5 0,04 PRSC 78 0.72 1-15 May 73 12 0.96 29 2 0.10 PAST 11 16-31 May 73 44 0,81 O.21 74 33 0. 99 1-15 July 1973 Intertidal Stat iona 1-15 June 73 16-30 June 73 2 17 0,00 70 0. 80 SHPE PRSC 1-1 5 July 73 1 17 0,03 MERI 23 0,08 0,39 16-31 May 74 1O 3SST 17 0. 17 0,14 SHPE 144 0,60 TABLE 3 PRSC 30 WITHIN SPECIES BETWEENSTATIOHSOVERLAP 1 - 15June 1973, CAfor Intertidal I! andSubtidal S! Localities CHUM vs,I! CHUH -S! 0,13 CHUM vs,I! 3SST I!- 0.21 3SST I!vs, 3SST S! 0,23 CHUM vsS!~ 3SST S!- 0,99 BXR s '5 5N--8 ~ 0 1-5-5 v ~ v 1

t42 143 species would then have high diet overlaps but par artltl on resources in some the st I ckleback,chum are specla I Ists, concentrat ing on fewer food Items ro o er way. n FIgure 2 we present another method for comparing the feedin get mostof their food. Thus,while the measureof overlapfluctuated con- of these 2 species. Food items for the times listeds e ln n a 1 bl e 2 2 were arrang- siderably, being high only half the time, chumspecIalized morethan stlckle- ed for each sspec ecfes es according to the order of decreasing !rnportancance as I n- 'a backln 70$ of the casesexamined. Wehave no informationabout the actual dicated by their contribution on to the percent of total biomass In the diet, locations of these potentfaily competingpopulations while they are feed!nq. Succeedlngbiomass percentages for these serially arranged Items w z Whendiet overlap is high, It would be of interest to know if the species u till he sums accumulated to 90% or more of total biomass. The successive feed In dIfferent places or at different times. sums were p otted agafnst the serially arranged items In Fi ure Z. Th n of the 14 cases the chum salmon required fewer llems to The foregoing analyses Indicate that rapid changes ln diets of fish species accumulate 90$ or more of Its biomass. This suggests that In comparisonto can occur in short periods of time. While chumsalmon and stlckleback harl hfgh overlaps C - O,SO! In half the samplesanalysed Table 5!, the rnsi oi the time overlaps were skewedtowards rather low values '. < O.Z!!. Olel 90 h- overlaps shift radir ally and frequently and are slewed tower d. el thrr high r . low values. Whenfeeding special izat ion 1s comparedswi tching in the degree of spec!al I zat1 ona Iso occurreda thouqhI the churnappear ed generally to be more speclai Ized than the stlcklcback. There Is evidence for the existrf>ce of short-term functional responses to changesIn prey density involving switch inq of attacks by predators to con- centrate disproportionately on the moreabundant prey burdock, Avery, and Smyth,1975!. Wernerand Hali 974! showedthat size selectionof prey In the bluegll! sunfish Is related to optimal allocation of time spent on seat-ch- ing andhandlfng prey. At lowprey abundances different sizes wereeaten as encounteredbut at high denslfles larger prey wereselected, Ivlev 961! surrmarlzesdata showingthat at low densities fish electlvlty for food items decreasesto zero. Beukema !968! foundthat an importantcharacteristic of stlckleback prey searchingbehavior was its non-randommovement. The fish avoidedre-visiltlng areas recently foraged'most fish restricting their ac- tlvltfes to areas where prey were abundant. Keenleyside 955! found that sticklebacks guidedeach other to areas of high prey density! Thesestudies 'Indicatethat complexbehavioral factors haveto be consideredin interpret- ing fish diet data. Wespeculate that group.oi fish speciesfeeding In areas like NanaimoRiver Estuarymight not only partition resourcesIn varir>us ways Schoener, 1974, revtew! but couldchange their feedinghabits radically and >.apidlyover short periods of time or over short distances associated with rapid changesin food densIty andcomposlt !on. In mixedgroups nf fish diets maynot only changeas a result of competitive interactions between speciesand changes ln foodavailability. It Is possfblethat mixedspecies groupsmfght facilitate their joint feedingefficiency. For instancedense mixedgroups of fish could makemore benthic prey available by sufficient d'isturbanceof the bottomthan wouldordinarily be available at lower densities of only one feeding species. Suchpossibilities could be evaluatedfrom experimentaland field observationsof feedingof mixedgroups of species. F lgure 2 Feeding selectivity and special i zat Ion In chum sa lmon o! and 5-spined stickleback o!. Cumulative percent biomass of food I!eras ls LITERATURECITED plotted against food items arranged serially In descendin d Anonymous.1974. Environment,Canada. Environmental assessment of Nanaiirno tion too o total a ood fo biomass. I Note that It general ly takes fe~er food Items Port alternatives. Lands Directorate, Canada, to accumulate 90$ or more of total food biomassss In n e th c hum I salmon than in the stlckleback, Beukema,J.J. 196B, Predationby the three-spinedstlckleback Gaatezv>stews acufeatueL.!. The 'Influenceof hunqerand experience, Behaviour5l:1-126.

144 145 CoCody, M.L. . . and J.M. . . Olamond Eds.!. . . 1975, , cology E and evolution of cornnun es. Belknap Press, Harvard University, Cambridge, 545 pp.

Foerster, R.E. 1968. Thes soc socks eye e salmon, Orfaarhyr!cue rfer!ra. Bulletin 162 Fl s heries r Research Board of Canada. Ottawa, 422 pp.

Goodman, 0. 1975. The t hoary of diversity and ptabliity rslaiionshlps In ecalogy, Ouart. Rev. of Biology 50:237-265. A "BUG'S-EYEnVIEW OF FISH PREOATION Ivlsv, V.S. 1961. Ex xperlmental ecology of the feeding of ffshes. Yale University Press, blew Haven. C.O. Lev I ngs EnvironmentCanada, F'Isheries and Marine Service Keenleyslde, M,H.A.' '1955. Some aspectsspec s ofo s the scschool fng behavior of f ish. Behavior Br183-248, W. Vancouver, B.C, May, R.M. 1974. Stability and camplexitp exi y n fn model d ecosystems. Princeton 0,institute Levy of AnimalResource Ecology, Unl vers I tyof Brit I shColumbia UnIversity Press 265 pp. Vancouver, B.C. Moros i ta, M. 1959. Measur inng i nnt erspeciflc association and similam ar ft y bet ween corrInunI t I es, Mem. FFac. Sc I . Kyushu Unilv. Ser. E. < BioI >3: 65-80. Understandingthedynamics of marine food wsbs involves aneiucidat Iorr af Murdack, W.W., S. Avery and M. E.B. Smyth. 1975, Switchin thefates of blamnssproduced byInvertebrates. Thorson 966! concluded fish Ecolo 56.'1094-'I'105 thatf sh predationhad a minorInfluence on the population dynamics of ma- rineInvertebrates, but data gather'Ing In many local studies emphnsizss Ibis Pui I I am H,R, 1975. Coexistence of s parrows: : a test of community theory. particularroute

146 147 "./n contrast, thepopulation dynamics ofan Atlantic arnphipod phntis reirrhItrr!i! These features seem to "buffer" th eamhlp p od p opulatlon form the effects of ilyingIn marine,subtidal habitats, reflects the effects of seasonalfish saimonld predation.n. Lif e istory h' observations on A. eonfetnrieolusn show that predationbyw Interflounder peeudopleuronectes ccnericanus! .evinqs, 1 97rl!. biomass increase Fl g, a can occur at seasons when u flounders,which were 'the most abundant f'Ish predator ln the studyarea, r h 00 o !r @no fr us !ceta! t ! are most abundant ln the estuary Aprl I- Ismigratedto the habitat when the amphipod population wasdominated byovid- May; Goodmanand yroom, 1972!. Juvenile amphipods Fi<,'q, lb! are the main ouesfemales. The predators removed these large individuals, thus contrib- prey for the young chum salmon.n. C o ttld ds maInl Le to utingto 0 decllne ln b'lomass FIg. 20, b!. P.rein!randi hasfow rofuqIIs In oI Jo fl hnl . 0 I orsi n he th esfuary Lev ln io Ita habitat.The amPhlPod builds diminutive burrows, bui I islevel-bIII tI»4 invertebrates are rare In th e estuary. t muddyhabitat Is relatI ve'lyunstructured, sothat the species Is moreacces- sibleto predation.The habitat Is subtldal,so fIsh predatorscan operate moreconsistently. Several predatory species of invertebrates e.g, nereid -JL!vranile Salmoi!lds-~ polychaetesand nemerteans! are present, Oatson mortal ity routesare required to ca I culatesecondary production, end I t ls of interestto comparethe siqni f 'Icanceof the vari ous factors for thetwo

AnisegernqraruS00nforvICOI05 P. IEO P porcsnrowsprorr ~ ftmorpp 40 -I Prcantjpwm505 ~0 D IP 50 ~0 O ~ I 4 PO O V 5o Crr 0 50 ~PI I 500 4 o Io C rl ~ I 50 CE

500

Ioo OEC. PPII Pco. 040 tr tr 592 50 15 5 IP 10 ~ tl I'pc4 IP»5 DEC p*w pE5 Iopt ~ rppt r44rc 4PII 04» 'VHE ruuy Wo. FigureIb, TemporaI changes in frequency of ]uveni les and ovi ger ous for»ales for A. eonferuicafws at theSquaml shestuary con l ra I sector!, Juvr.ni le, Figureg a. la Temporal change In b Iomas definedas organisms passing through a 1.7mm mesh screen. oT tt .S q Ish estuary central sec or!. Sam qua rats at low tide In sedge rhizome mats d 951 fid f' It f or eac sampleare shown.

149 148 I wenZZIao>!SSoo>ela W'>>SH 0 0 IP amph1pods.For a given time Intel-va!, lnstanteousmortal ify late m! can be dissected as follows; An>',acga»znaruaconfer uo'.cc>t»e > 'm = Sp + Cp+ Ap + I. f N, where Sp= salmonpl edatI on,CP = cottid predatI on, AP= avian bi rlion, L = loss term dueto tidal "export" from the esii>ary, and N = "linlurul" mortality disease, senescence!. Vu ji P!>obo'erein!layoff: m = Fp + Ip + N, where OI5 OlD 0IO F = flounder predatilon~ I = Invertebrate predation, and N Is as aiiove. 20 0, L 0 C MeaSurementOfthe lOSSterm far the > StuarlneamphlpOd ISa majcrdi tl ieulfy, OlO 3 0 given the vagaries of estuarine circulation. 4l O'0O w c Tidal creekspenetrate the marshhabi tats at the Squamishestuary, ai>l;. A '0 0 PI+ beachseine was used to blockthe seawardend ot the>.reek. At higli 0 0 Ol 0 0 'OOlL C L 4uvenille churnsalmon conditioned In the I aborafo>p to a vallety of prey were ol I 3 pl0 IOt. Introducedbehind the net. Throughcareful selection of timesand tides, ex- IO' lit OC-'0 perimentslasted up to 14 hours, spanninglight and dark conditions. lish Il Ol Cl 0 collectedat lowtide whenthe cre>.kdrained, and about 20$ of experimenlal OlI IiI/I C! 0 Io fish wererecovered. Morefish could he recoveredIf concreteor woodenrlms L C 0wa OO 0 C II C,X wereconstructed, Preliminary results showthat juvenile chumsfed mostly on 0 0 IOl 0 2 O 0 COlII the organismsthey werecondftloned to. Thetechnique could be used to C O.>- C Ol0 C u> R ~ L OO determinerates of a numberof feeding processese,g. consu>nptlon. WORN II> w 3 Ll O a CIO .C IOL 0 e' C IJ0 0 >3I- ol Q LITERATURECITED C C N Crl0 c 'OIO L C 3 C L c Ol0 Goodman,D, and P.R. Vroom. 1972. Invesfi getIon into f ish utl I ization of the Pi I, i c 0 $e-~8 ~ IOIII Inner estuary of the SquamlshRIver. EnvilronmentCanada, Fisheries arid O''3 IO III Ol 0 MarineServilCe, VanCOuVer, B.C. TeChnICa I RepO>t NO. 1 972-I 2. 52 pp, C 3 0 O IOg IO O Levings, C. D. 1973. intertidal benthos of Squamish Estuary. F Ish Res. 0 L0 C0 L p Board Can. Manuscript Report No, 1218. 60 p. e '33 F II! I. 0> L R;0 1974. Seasonalchanges in feeding and particle seilection by winter floulider >I Pae»dople>oronecbeeamer>',can»eJ. Trans. Amer, Fish, Soc. 103:828-8U,

i IO 1976. I>!ver diversion and Intertidal benthosat the SquamishRiver delta, 8 itlsh Coiumpla.o 0 Pp. !93-204 in Skreslet, S., R. Lelnebor, J,B. L, Alalthews, and E, Skashaug Eds.!. Fresh Water on the Sea. Proc. Symp. Influence 0 Fresh Water Dutf ow on Blologlcai Processes in Fjords and Coastal Waters, 22-25 April 1974, Gel o, Norway. Assoc, of Norwegian Dceanographers, Oslo, I II Ol CI>>nIJ> l>>I>lJI 4 »aJ» f»i>Q Iuea>ad Muus, B.J, 1967. The fauna of Danfsh estuaries and lagoons. Distribution anil ecology of dominating species In the shallow reaches of the mesehaline rr>ne. Meed. fra Danmarks Fisk,-og Havunders, NY Series! 5 I!:3 I?.

>ivy, D. 19 6. M.SC. Th eS I SIn n progress. Inst. of Animal Resource Ecology, linlversity of B.C. Vancouver' B.C. I i' >I ll J>fill Sananders, H.L. 1968. Marine benthicc vers divers lt: y: a comparnt I ve study. Amer Natur. 102:243-282.

Taylor, R.J. 1976.976. UalueU of clumping to prey end the evolutlonar re of ambush predators. Amer. Natur. 110: 13-29.

Thorson, G. 1966. Some factors Influencinn uenc ng the he recruitment and establ ishment of marine benthlen c communities. Netherlands J, Sea, Res. %!:267-293, PRELIMINARYOBSERVAT IONGON ! NTERACTIONG Ware, D.M. 1972, P redat'ion by ra!nbow trout Salmoa o Ifdzfrdnerf qf I: the Inf luencm BETWEENTWOBOTTOM-FEEDlhIG RAYSAND A of hunger, prey densitens y, and prey r size. J. F Ish. Res, Can. 29.'1193-1201. COhf4UNITYOFPOTENTIAL PREY I'N A SUBLITTORALSANDHABITAT INSOUTHERN CALIFORNIA

Glenn R, VanBlarlcom Scrlppsinstitution of Oceonoqraphy, A-OQB LaJolla, CA Thedevelopment of standard techniques for fish diet evaluation Is a vltaistep toward the understanding of a larger Issue, ihe nature of Interactionsbetween fishes and the communities theyexploit for food. Thepreferential removal of certain kinds of preyfrom a broadspectrum of potentialprey can have a keyrole In determining demographic and distributionalpatterns ln preycommunItles forexample, Brooks and Dodson,1965!. Direct observation of prey consumptIon byfishes Is difficultto accomplishona regular, quantitative basis. As a result, stomachcontent study ls a primarytool for describingfish diets, However,anInvestigator relying exclusively onstomach content data assumesthatthe impact of fishpredation ona potentialprey assemblage canbe fully characterizedIn terms of preyeaten by the fish. This assumptionmaybe inappropriate forcertain systems Invo'Ivlng demersal predatory fishes. Duringsome three hundred SCUBA dives on the subtldal sand plain near LJ II,C Itf I,Ubh, I hb*dthd tlgyU~lh h II ~I

153 152 I ln its f ina I form. This work was supported by a dactora I research Improve- 'lhhl I. P I~ IPIP y lt F* dl Bt I, td~lh, h ment grant, NSF !fOCE76-05812from the National Science Foundation, PreyCategory Frequencyot Meanf per Mean$ Valutyle Methods Importance Occurr nce !5! Stomach ef Stamhgh Rank Al I benthic sampling and behavioral observations were done af the primary 2 206.0 92.5 study site directly offshore from the Scrlpps Institution of Ocean- ~Ntt I P 20 ography in LaJol la. The study site Is sixteen meters deep with a bottom of wel I-sorted fine sand of low organic carbon content < 0.25K>, and B~lh I d* 3D 8. 67 43,3 Is roughly midway between the Scrlpps and LaJol la submarine canyons, occldentalls ~RU Rays used for stomach content evaluation were collected at or near the 1,0 100.0 main study site by spearing or with bat!am-anchored set line; checked Harenactis 10 at 2-3 hour hou IIntervals. Stomachs were removed immediately after collec- attenuate tion and fixed ln 104 formaldehyde solution for 1-2 days, then dissected 2 y and analyzed. For each prey species, numbers of indlvlduals and 25.0 90. 0 percent of total stomach content volume we r e d et erm I ned. . Prey species ~Dls lo uncinate 10 imporiance was Inde> ed by multiplying prey frequency percent of all IN t non-empfy stomachs which contained the species! by mean percent' volume 40.0 of stomach contents for the given species. Pectlnarla 20 caI!forniensls Benthic anima! densities were determined by collecting replicate sets M~t n=2 or 3> of hand-ape! ared cores. The cylindrical c~r c rers rs wwere f o wo t 6 2.0 23. 3 s zes large: 0.018 m surface area; small: 0.008 m area, both ~k* t t penetrate 10-12 cm into Sediment!. Cored sodlmentS were scrd!ened meSh 2 17.0 25.0 openings 0.5 mm!, fixed In 10$ formaldehyde solution for I-Z aays, then 7 tie! M~IP 20 stored In 70$ Isoprapanoi prior to sorting and countlnq. Coring 3 5.0 50.0 techniques were used ta asse s recovery of benlhlc populations IF! both Plnnlxa sp. 10 natural and simulated holes formed by hand-fanning bottonh sa»ds until 10.0 the dlmens'lans of natural holes were obtained! ray disturbance sites. Unidentifiable 40 SmalI corer arrayS were used to deteym inc the SpatIal extent of faunal polychaete parts disturbance associated with ray f2 eding halos far both Myilobatls corer 6.0 .0 y h I Flg * II d ~U 10 tie! Anchlca I urus 20 accldentalis Rates of ray disturbance were determined In two permanent conti guous uous g~l meter belt transects at fhe maly! study area. Extanl ray p'lfS 4.5 10. 0 weie marked with small stakes such tha! on a subsequent resurvey Cancer sp. 20 usually 2-5 days later! new pits could be counted and measured, allowing computation of a disturbance rate, expressed as percent of total 2 18.0 20.0 transect area disturbed per day. MonocuI sp. 10 20.0 Decapod megalops 2.0 Results larvae 5.0 20.0 The ten prey categories most important in the diets of a modest sampling ~AIheus ciamator 10 ~UI I I =I II ~~ d Myl I 0 tl I =yhl are shown in Tables i and 2. 0 kl gt~ Table 3 lists the ten most numerous benfh Ic spec'les In large cores collected In J une-August 1976 fram the maIn study area. Data In Table 3 are for cares taken In "baseline" lacat lons, I.e., in areas which have I! Emptystomachs n=l ! excludedfrom data, ! GammarldAmphipod, ! not received recent disturbance from feed Decapodcrab, ! Coelenterate,! Pol ychaete annel id, ! Fiolathurinn Ing rays. None of the important echlnoderm,! Cumaceancrustacean, 8> Decapodshrimp

154 Tab i e 2, Pr Inc I pal Prey Items Found In Stomachs of M~llobat I s cal I lorn leg Table 3. Abundant BenthicAr61ma ls from Core Sampi lnq of PrimaryStudy Areal Importance Prey Cateelory Frequency of Mean ¹ per Mean 4 Volume Stomach er Stomach Mean ¹ per Range Frequency Rank Occurrence $ Species Mean Abundance Core Le>>to~sna~>lasp. 64 5.3 59.3 Rank ~ph 6 I 79.6 21-133 100 83.0 Lollcao o~talescens 27 4.5 Barnard Be.rrya 7 I ll~tl l9 B 10-28 100 Dphiuroldea 27 2,2 31. 0 ~Da'I I Large uniden- 18 1.3 16.1 5-27 100 tifiable bivalves B~dheteruro us Unidentifiable 13.9 5-17 100 pOlyChaete parts Rutlderma rostrate ~Jd 9 Llstrlolobus 14 35. 0 elodes ~hll B~ 5 ~ 1-22 100 Fisher Holmes h I pll 4.5 1,0 40. 0 Moselle tumlda 5.5 2-10 100 Carpent~er> 2 ~C 4.5 I.O 70.0 ~dh I ld I 9 ~ 4,5 1-1 I 100 ~ I Locklngton Medlomastus acutus 4.5 0-8 83 ~H*9 UnI dentl f lab I e 1.0 10. 0 fish parts hhballa u ettensls 4.1 1-12 100 C'lark> IO ~PhI I o~sad I x 23. 0 1.4 7 0-9 83 ~tor re Bd d I II p. 4,0 tfaisono 10

I ! Basedon 12 large surface area 0.018 m2 !core samp'les forcrustacea ~ 6 largecores for other species., ! GammarIdamphipod, ! Bivalvemol lus ! Ostracodcrustacean, ! Polychaeteannel ld ! Leptostracan crustacean, > Coelenterate I! Empty stomachs I'agurld decapod crab, ! Decapod shrimp, ! Mat Ine angiosperm plant

156 157 foadspeCieS for eitherray appearS in the I ist Ofabundant ben'litic fauna.WIth the exceptionsof Monocutodessp. f = 614!,derapt>d mega'lopslarvae t = 25$!,and I eptosynaptasp. f = I6$!,none of thc p I II tdhd I g~yg th lpg I ~th "baSelprey splneu COre SampleS, and mO t hadfrequenCleS Of ZerO. Data trcfg coresamples taken In a numberof locationson the subtldalsand hab'Itatnear LaJoila suggest that the preferredprey are un Iformfy rare ratherthan occurring in isolatedhigh-density patches such patrtfied;s mightexplain the Importance of the prey species if rayswere ably lo locateareas of locaI Iy highabundarhcs '!. Data from vert Ical ly parI il.ioned coresindicate that virtually all infauna Including most sped Ie . Ocm foundin TablesI J 2! I ivewl tttln 5 cmof tho sedirrlentsurfacn. Iltu, RAY it Is doubtfulthat 0herareness of the exploitedspecies Is an artifact of inadequatecorer penetratlon Into the sediments. Mostof the preferredprey species Ior bothrays have body s resI m,yflr timeslarger than any of thespecies listed In Table3. Thusthc nvusl. commonbenthic species may escape consumption by foragingrays as a Figure I Sarnpl lng layout of PyZt.obdzbra cabr.fozvrtccr disturbance site, SmalI COnSequenCeOf their SmallSiZe. HOWeVer,data fram COre SampleS circles represent positions of cores relative to the ray hole. Distances shown fromnatural and simulated ray holes of varyingages suggest, when were measured between the ray hole center and the inner edge of each core. comparedwith "basellnew samples, that ray disturbance has importanI andcomplex effects on populationsof the abundantspecies, F Iure 2 showssurrrned abundances of benthic crustaceans in tri p lestI c setsof largecore samples taken fr om natural ray hot es and "basni i rye" areasduring summer 1976. All rayholes sampled were newly farmed in the permanentbelt transectsbetween 14 and 16 July 1976.No ray holewas sampled more than once. Datashow an initial depre sinnof crustaceannumbers in ray holesrelative to undisturbedsedirnerlts. Ten L!200 dayslater, the surrined densities had recovered, butindividual species K abundanclesIn the ten-dayray holesamples differed considerably from O "baseline"cores, with numbersof thegammarid amphipods ~Snchelidium O p., M I d p., U I I t II d B d d A i~d ~ht B ~ d *dl g I I I d tl g I I I the recovery.In the 31-daysamp I es the crustaceanfauna of the ryay D 100 disturbancesites c:loselyresembled "baseline" abundances, both irl B summeddensity and In numbersand ranks of componentspecies. O A simlI ar pattern appeared In a raydi sturbance simulation expcrlmcry 1 X rundur ing winter 1976. On f ivedates rept l catepairs of coreswt:re takenfrom s imuiated ray feedingp Its dugon 29 Jan. ! andadjacent undisturbedsands. Figure 3 showsthat the Initial depletiono sufnmud crustaceannumbers was followed by a recoveryphase In whichabundances 10 JULY 1 AUG 15 AUG exceededbaseline levels. Threeof the four specieswhich were early colonistsof naturalray holes IJ.entalladurus was the exception!plus Flqurc2. Recoveryof benthic crustaceans srimof atI species!tnnatural t th lth phlpodM~I p. d th Ul raydisturbance sites. Samplemeans from disturbance sites are represented tenuisZImmer! were responsib'le forthe over-compensation in thesimu fated byopen circles and solid lines, those from adjacent undisturbed areas by dist'urbance pits. Theexcess summed crustacean level s andthe tl if!h drnsi- crossesand broken lines. Verticalbars show ranges for each!riplicate t ies of earI yco loni z ingspec i cs pars i sted through a secondsamp I in: date,22 days after the disturbances were made. The 33-day samples sample set. showednoImportant differences In thecrustacean fauna of disturbedand

159 undisturbed sediments.

The response of combined palychaete densities to simulated ray disturbance, shown In Figure 4 was somewhat different than that of crustaceans, Numbers were Initially depressed by the disturbance event and recovered slowly, Iz: 200 converging with undisturbed dens Itles In the 22-day samples. Abundances O of component polychaete spec'les In disturbed and undisturbed sands were Cl similar at the time the sunmed densities canverged. CD 5 tl pl* y ll*td I I dl gh*l* f d by~01 h pit dl 20 I d~MI btl I dl ~ 5 I p idd ld tht I 100 the areal extent of disturbances appraxitnately corresponds to the visual ly perceived dimensions. These pal terns were consistent for al I Cl crustacean, bivalve and polychaete species which were sampled In numbers z sufficient to determine spatial patterns.

Nine pairs of trar sect surveys were made to determine rates of ray disturbance to the sediments by foraging rays. The mean rate was 0.55$ f FEB of bottom area disturbed per day range: 0-1.69$!, with highest rates occurring during the warm water months of August and September In both Figure3. Recoveryof benthic crustaceans were Included In the smal I radius mode, suggesting thtp~ oh I I prt tth M~I btl fb thl cotmnunity disturbance.

Discussion 30 A system described by Orth 11975! ls similar In many ways to the situation 1 have discussed for southern California. Orth has descr'ibad the for- OCD O glg tt ltl fg p f y ~Rh t b ! hi h frequent the shal low sediments of Chesapeake Bay during summer months wC and employ foraging techniques described by Ifilgelow and Schroeder, 19531 15 hih PP *tly b th I h b d I ~ ~UI h h 0M~I btl llf I . 0 Igth f 9731 g g p f a a R. bonasus damaged or el lminated large si ands of eel grass Zoster a marina l, to the cons I derabl e detriment of associated epi f aunaI and Z infaunal assemblages, whl le digging far their preferred bivalve prey. Stomach content study showed that most species reduced ln abundance were unimportant as prey for R. bonasus. 0 FEB

Data trom my preliminary work in southern California iend support to the notion that feeding activities by two rays In a sublittoral sand bottom Figure4. Recoveryaf benthic polycltaetes sum of all species!In simulated community provide predl«fable physical dlsturbanceS 'lO tide rays. As ray disttfrbancesites. Symbolsare the sameas thoseIn Figure3, a resu1t, rigorous e~perlmentaI testing of this hypothesis ls now under- way. Techniques Include thr. controlled use af large cagd.' which protect areaS of fire bof lorn In rhe malrt study area frOm tire dlsrulttiue effeCtS ol foraging rays. Repl i cate sets of experltnental and control ca tes are now In place and w II I be sampled In early November, 1976. These

161 160 studiesare beilng supported by expandedcollect fons of raysfor more satisfactory dietary chaFacterlzation and b xt I of benthic fauna. n y ex ens ve core sampl lng It Is apparentthai theeffects of predatoryfishes on the structures of ccmmurrit les of potentlel preypopul ations cannot, In scnrecases, be adequatelydescribed by analysisof stomachcontents. A full d g a fish s functionin a preycommunity requiress ~ u knowledgeUn er- of the impactof foragingact ivlty onpopui at lons which are not f d as f ood. Thus, the 'Improvementof f1sh diet a»aI f ical technle no pre erred be accomp anied ' b yex expandedstudies on the natureand conseq f fish feeding behavior. nsequences o

L IT ERATUREC IT ED PRFYORGANISMS AND PREYCOMMUNITY COMPDS1T ION OF JUVENILE SALMONIDSIN HOODCANAL, WASHINGTON Bigelow, H.B. and W..C. Schroeder, 1953. F lshes of the Western North A4ant ilc. Part I I. Sawflshes, Guitarf ishes, Skates and Rays. SearsFoundat ion for MarineResearch Y I LI I It Charles A. Slmenstad a e n vers y, New Haven, Fisheries Research Institute, Unlver s'Ity of Washl»gton Brooks,J.L,, andS. I, Dodson,1965. Predat ion, Body S ze,I and Compos I- Seattle, WA tion of Plankton. Science, 150: 28-35, Orth ~ R.J,, 1975. . Destruction of Eelgrass, Zosteramarina, by the For the past 2 years, Investigators at Fisheries Research institute have con- C Ry.~Rhi t b ., t th Chb-p k B ducted intensive sampling of migrating juvenile salmonlds, principally chum Chesapeake Science, 16; 205-208. salmon and pink salmon , gorburrcfrrz!, during their early marine life In northern Hood Canal, Washington, These studies have Walford, L.A., 193'5.The Sharks a»d Rays of CalI fornia. CalI forrria been funded from the OICC Trident Environmental Monitorl»g Program. The Departmentof F shI and Came,F shI Bu!I etln 45: 1-66, objectives of these studies are to monitor the movementof juveniile salmonlds along the stretch of Hood Canal which Is the site of the U.S. Navy Tride»t submarine base; and to evaluate the potential impairment to this migration caused by actlvlties associated «Ith the construction ot piers, wharves, and docks along the base's Hood Canal shoreline, including the effects of dredq- Ing, of the Impact of the installations themselves, and of the proposed 24- hour lighting of the shoreline environs at these taclllties.

in conjunct1on with this sampl lng program, representative specimens of juve- nile salmonids were retained for quantitative stomach analyses in order to document' the importance of near shore shallow subllttora! and »critic prey organisms in the cr'Itlcal early marine IIte of these fish.

In addition to the v'lew of the juvenile salmonilds' early marine habits from the "Inside out" via analysis of the stomach contents, preliminary sampling of epibenthlc and neritlc plankton communities was also attempted i» order to relate the spectrum of prey organisms consumed fo those »available" in the nearshore environment at the time of migration.

The purposes of th'Is paper are briefly to descrilbe I! the techniques we flrrd optimum In sampling juvenile salmonids during their early marine residerrce, 2! an epilbenthlc suction pump which we utilized to sample epibenthlc nla»k- ton, 3> the prey organisms consumed by those fish during their migration along the northern Hood Canal shoreline, and 4! the composition of thn sha!low subl'lttoral eplbenthlc and »critic plankton assemblages as samirlrd by the eplbenthlc pump. 162

163 b th ! nd substrate e, q., qravel, cobble, androck unavali.!bli! MATERIALSANO MET»-OO'S over the ben os an to corers !. . so, Al It can sampleat any position In the water column P>edator Collection a sledge>and cari provide an accurate >«n!sure of the qiinnt I tyof w,!Iiii strained. Two i«ethods were n»cessary In our juvenile sal>nonid collertlons--beaah sein- t F I . I > con,isted of a sol f-priining, gasoline-power> d, ing and tow >iet I ing. Tiins» i«ulh~!ds eiiabled us to csi!Iuri bi!! h scliooled The pump sys em g. 'I t d I inkiui s 5,.1 -cm -1 nc h! centrifugal pumpwhIch draws ~ater andassoc a e p in vis early i »S ident I 1Sh In iiie 40-60-«>mS IZ» range dur1 >i>Zciayl iqht w!ien they 25.4- 0-inch! conleaf expanderInto a 5,!-cm f iexible p as i, migi ates th> ough the shoie! lne shal lows, and Iar>!e> f ISh In !he 70-100-mm through a . -cin hose, 0 nce th roug I! the pump the wafer samplepassas through a seal»i!-reg- size range whirk oi copy t I«' iiiii' I 1I r: wa> ers !arthur' oi fs'ho e at n lght. t t I I I f I meter Into a double stainless steel cy I ndei n w ister, d tota . z ng I ts owmo were e suspended. Tlia nets wereof 505-»and 20>i-v 1he beaCh Seine iS the Same One uS»d in the In tituie'S nOrth Puget SOund 2 nested conica ne s were I ~, I hi and Strait of Juan de Fuca b,iseli ie studies: 37 m 20 fi! long, equipped meshsizes with area/aspectratios of I:2.54 andI:5.3, respectively, hi w! th '18-m 15g-ft ! lori I, 3 i«m I I- I/8- inch! r«esli win>J», anif a 0.6 m x 2.4-m x epibenth'ic organisms were i etaIii»d in standardnet bucketswith window 2.3-m bag of 6-i«>n I/4-in<>i! «x!sh, T>ie riet as used i>i tlie juveni le salmonld screen of appropr ate mesh size. studies is equipped with 1 iota! lon sufficient to keep the riet f Ishing along I t wasoperated from aboarda 26-ft boat maneuveredwithin the sur face. The nets were,et by smaI I boat di>r ing day I I ght I ow slack tide, The pump ng sys em 30 m away from and parol i»I Io thi! boacii, and wore retrieved to the beach by about15 m ofthe beachand ai!chored. SCUI>A-equIpped diversthen proceeded hand at approx 1 >«ately 10 m/«iin. T iie I ines a I I ached to the pol es at the end to surveythe bottomand to placeat randoma I-m diameter metal hoop of each wing were initially >>au!ed from positions 40 m distant until 20 m . 14m area>over a representativearea. Thepump was started and the of line had beer> retrieved; the, net was than >-.Iosed down !o a 12-»> open lnq suctiontl hoseh d en was as passepassedto the divers whomoved to the chosensampiliig and retrieval to tfie beach compleied. his net could sample all shoreline location. Upon a s I gnaI from rom the boat the divers beganto movethe expander habltats except those rharaclerlzed by very dense eelgrass or kelp oi with coneabout IO cm off the surfaceof the benthoswithin the samplinga>ca, large boulders. "vacuumIng"the epibenthicregion, FourproJectlng bolts on the expander wereused to stir 1'hevery surfacelayer of the benthos,Several seconds Tow net collections were i«ade with a 3-m x 6-m IO-ft x Z'!-fl! surface trawl, after the diver hadinitiated the suctionsampling, the 2 nestednets wore with mesh sizes grading from 76 «m> inches! at the mouih fo 6 mm I/4 inch! !thin the steel cyl inder. This lag time ensured tliat at the cod end. This net is towed ai night between 2 vessels at approxl- the waterand organisms within the pumpingsystem at the star ng ime mateiy 4 I m/hr for 10-minute tows alonq esiabllshed transect lines, both assedthrough before the netswere In placeand filtering. Onehundred parallel to shore !approximately along the -6 m depth contour ! and fn zigzag umed throu h the nets before the nets wereremoved and thi. transects across the cana!, - I I I d t stop samp!ing. Organl sms were removed f romtha a p,!n I!nkton net cupsand preserved ln 5'gbuffered Formalin in labeledd PUC Jars. ars. Fish destined for stoinach ionteiits analyses were retained in anesthetic and preserved In 10$ buffered Formalin with the abdominal wall slit. The samp'I I ngcess process wasw repeated for 3 repllcates,the samp'I'Inghoop beinq movedto a newarea of sfmllar substratefor eachsample.

Prey Organism Collection In the labors t oryth e ep Ibenthlcplankton samples were transferred to $ Isopropy I I a co h o I an d stained with rose bengaldye, stirred, and allownii to Earlier preliminary studies of the diets of juvenile salmonlds In north liood sit for at least a weekso that organiismswould be completey s a nc . e Canal Kaczynskl, et al. ~ 1973; Feller and Kaczynskl, 1975; Slmenstad, fn organ i smsthen were en separatedfrom the sediment and det r Itus In the sa«iple, press> had indicated the iinportance of eplbenthic plankton, especially t d t the lowest t'axonomlcleve'I possible by exam'Ination rougi a crustaceans. Unforfunate1y, there fs little information on the epibenthlc dissectingmicroscope, and total countsand weights to nearese r st 0,01 ! ware plankton communities of tlie shallow sublitioral regions of Pugot Sound. obtained for each taxon. They cannot be effectively sampled with traditfonal sampling 1echnlques such as plankton net Paws or wiih intertidal transect cores or quandrant sampling; nor do more appropriate epibenthic samplers such as the several developed Stomach Analyses eplbenthlc sledges Holme, 1971> appear to be efficient gears when used in shallow waters, Stomach cont ent s o f th e ju ' venl le salmonids wereann I yzedaccording to a sysemat t I c,t san dard a ized quenti tatlve procedure,described ln de>!i I !iy After the success oi an eplbenhhlc pump sampler used by rel ler ani> Kaczynskl Cath Terry cari ier In the courseof this work;hop, 'liis»!> o pr;» I'775!, a suction pump utilized for sampling nearshore plankton 'In the the numericaland grav !metr I cco>«posit ionof preyorqa>ii sms contai>ied in Aleutian islands Burgner, et al., 1969! was modified to sainpfe shallow sub- the s tomac h the degreeof fii! inessof the stomach,arid the state of iiltoral epibe>ithic pianktoii. The advantage of this type of sampler Is that digestion of Its contents. the researcher can sample In almost any habitat ft does not have to be towed

164 165 STEEi CYLINDER g,BASF Sampling Sites Ourlnq peak mlgratlo

RESULTSAhlD OISCIJSS!O!!

LJCTIC!N Prey Organismsof Juvenile Saimonids As Indicated

167 166 SEINE rs

Z Q

II1I jr1 1Ir I I'1'II1II1I 1 II1II I I1 11'I' -' SITES PREYCOlvrPOSITICN

Representativefr ev siss position of ] uvenile chrrs,Oncor hywahus ks ia, and piirl salmin, P, ENTH! C/NERI T IC rfostruechrr>in shallow sublittor al a! and ner'itic b! waters of HoodCanal, Washington, PI ANKTON PUMPING April-Hay ~ 1'376~ Bench neirre, tovr net, and cplhentlric pliankton pumi anmlrling sites along Bangor annex replan of pood Cana! rrt 1 lized fnr collection of rsiprar ing ]rrvenile aalrrasnidaand epilrentlr tr prey assemhlaprs 169 168 calanafd capepods,and leptostracansas they got larger, while fhe chumsap- ld epods gammerl d amphipozls, oral their eggs aro a II sampi"I peared ta continue their feeding preference for harpactIcolds, although with the pump, though with a wldo range In var iabl I ity. s w e inc leptostracans had also 'Increased In Importance in the chumdiet, dence of these crustacean eggs 'In the predator's stomach, the occurronca oi separatesep t od a s ao egg cases in the pumpsamples pz>ses a problom. F th>I < Nighttimetow net catchesIndicate that larqor juvenile salmonldsoccupy the the umping process 'Is separat'Ing the eggs fi am iho ovllosr» nerit c waters off the HoodCanal shoreline, aI/houghnot In denseschools are much more freely avai labia In the environment than wo as>urn|1. as foundalong the shallowsublittoral duringthe day. Nerltic-occurring these eggs are muc mo j uvon le chumsand pinks were more catholic in their diet and tended to These pump samplesI I a so I od ca I ate e that it may be feasible to detect the ch;>n-I- concentrate upon larger pelagic organisms. There stfii was considerable con- Ing abundancesof oplbenthlc plankters with t lmeand seasonas welI tribution by harpactIcofd copepodsand gammarld amphfpods but they mayhave I I lustrate definite e n e n Interhabitat e differences in avai fable epibenthic prey. beena remnantaf daytimefeeding fn the shallowsublittoral, dependingupon I s carl also provide 'Intact spec/mens necessary for eva ua inq whenthe ffsh sampleswere obtained, Clupeid larvae were ilmpartantIn the The pump samp es ca dieis ot neritic chumand pink salmonin April, typically dominatingthe prey the life histories of many of the more important plnnkters, compositionby bilomass. Approximatelya monthlater, decapodand clrrfped Plankton pump samples es from rom nern it fc waters are def in i tel y more diverse i hen larvae, insects, and calanoid copepodshad replaced fhe fish larvae as the from I l>el>e shashe I low ow subsu I lttora I, though not nocessari ly more vari able. v u r most Important prey organisms, At this time the diets of neritlc chumsand or not It samplesmany of the larger, more mobile ccmpo nents of the noriiir. pinks had becomeslighrly moredivergent, with chumsconsuming a greater plan kt on ava Ilabfe a e to juvenl'le salmonids Is fhn question. Far Instanr,o, percentage biomass of calanold copepodsand decapod larvae while pinks had I d some decapod larvae may not bo represented n e sa p consumed more clrrlpod larvae. fish arvae an som proport i on t oth e I rccurrence a In the environment ~ or perhaps no at a Again, ththl s may b ea a function unc moro of the patchy distributionti n f o oso thoso Eoibenthfc Plankton Populations plankton than of the sampler itself.

Preliminary sampling af shel low sublittoral epibenthic plankton with a mod- ! 1led suction pumpindfca+es that, with someImprovements, this systemmay Juveni'le Saimonid Oiets and "Ava'liable" Prey Organisms provide a valuable sourceof quantitative Informationabout the composition A pre i iminary comparI son of juveni I e chuma nd p Ink salmon p rey organism" with oi prey organismsavailable to juvenile salmonids. As a tool for sampling II s ectrum ot epibenthic and nerltic plankton available for con- neritic plankton, however, it may need further reconsideration or somo f ' Ile salmanld modifications in sampling desiqn. sumption Fig 4! suggests some Interesting aspects o juven ,e feedinq behavior.I . I nlh e ssha a I low ow subl i ttora I, juvenl le sa lmonlds pr oforen- tially consume th e sma smaller e less abundant harpactlcoid copepods rather r»e»he numerIcal and qr avfmefrlc co~posft,an of ep>p b d t mmarid amphipods. Although the Incidence o Iqam- am- plankton at 2 shatlow subilttoral sites and I neritic si te at Hoodlanai, marid eqqs suggests that the salmon may attemp'1fo prey upon adult qammnriammnrids,s, March-May1976. The abundanceof organl smsI s shownfor both the 206.u b, bl t ingest them becauseaf the amphlpod'ssize or and the 505-umesh samples, and for the larger organismsreIalned by the they may oo e a e o ng tivity. Despite the f ac-t th a t the eplbenthic pump samp'les did not illustras e 505-pmesh net, biomassi Indicated wherepossible. f I . t t racans these small crustaceans also formed a a reat9 abundance a ep os P f th I kters consumed In the shallow subllttara!. i he composition of our samples t aken at the Tr I dent base wa s imiI ar to the large percentage o e p an campositionfound by Feiier andkaczynski ig! in their epibeothicsampling I I .-f din 'uvenile salmonlds consumed several organisms which either of Dabob Bay~ Hood Canal. Nerlt c ee nq ju were nat aounuanb d t mponents componen of the nerit Ic plankton or were n e ' y sampled by the pump--e.g., um--e.g., cclriped larvae, clupeiid larvae and nsects. s. Al- Total numbersof organisms sampledby the epibenthic pumpare within reason- Il th important prey In this feeding realmm arer larger er than an those In able variatlon < 50>fof mean! over the 5 replicate samples taken at each mast a e the shel low su blitt ora I wh'Ich may be because of the larger sizes ol tho site, Valuesfor the total biomassof organismsretained by the 505ip mesh tions. net are considerablymore variable, whichmay be due to the lack of precision nerltlc salmon and nighttime feeding behavior In I'Imlted light condi on of the weilghing instruments when very low wefghts are Involved. Principal salmonidprey orqanisms are effectively sampledand, in somecases, Summary haveacceptable values of varfablllty about the samplemean abun I I y of the mean.Whether this is a fault in the samplfnqtechnique, or is gen- Id copepods. I.ar qor salmon zfroaled uinely descriptive of the spatial distribution of ciu.,tered populationsof smatl crustaceans such as harpactlco than 50-55 mm, aro prone to feed In nerItfc waters upon larqor pl >nkto> -. orqanisms Is not clear at this time. We intend to make further modifications c pump sampler h*S boen Shownto pr<>v'Iziz to the sampling design in order to reduce variabfiity attributabln fo the Inciudlnq fish larvae, An epibenthl sampiinq technique,

171 170 In a reasonablequantitative sample of the avallabfe eplbenthlc pier>kton &Pl"0 nI aI assemblageln the shallow subltttoral feeding envfrons of theJuvenile ~pl& l&n In salmonlds,Nerit Ic planktonsamples tended to be lessrepresentatfve PI l&1 E of the spectrumof preyorganisms ave Itable to nerftfc-feed'ngsalmon, nr In Comparisonof salmonid prey composition with epfbenthfc and nerltfc In In planktoncomposltlorf suggests that smallerdaytfme-feeding salmori are C preferentfally,or functionally,consuming the largerorganisms In 0 the preyspectrum. Further sampling, and mare detailed, must be +- In C I performedto elucidatesome af the factorsinvolved In this apparent 4&IPPPII In n selectivityand to evaluatebetter the relativeavailability of the different prey organfsms «Ith time. ~ &%IS&1 a 0 +- In ~ 1&4 L ITERATURE C ITEO P44n Lrn 4 4&&&44 c L a. Burgner,R,L., K,K.Chew, J.S. Isakson,O.A. Math lsen, P.A. Lebedn 1k, ~4+ DIn c R.E.Norris, C.E. O'Clair, M.M, Peck, C.A, Slmenstad, P.N. Sl attery C 0 In andG.J. Tutmark, 1969. Research Program on MarineEcology and Pal3 rrI Oceanography,AmchItka Island,Alaska. Annual Progress Report, +.0 July I, 1968-June30, 1969.Prep. for BettelleMemorial inst., Ih BM1-171-128,76 pp. 1I 3 In Fefler,R,Jlp and y.W. Kaczynskl. 1975. Sfze selective predafion by a 0 c Juvenilechurn salmon

171 00000 0 0 Table 1. Tax» composition of epihsnthic planlrton sampled by epibenthic 0 0 0 0 OQ 0 0 pumpat three sites in ilood canal, I arch-Hsy 1976. Values +I LI LrLI Cl II II are per lDD gallons pumped, cia e +I» e Iv EI e! 44rmcc 0 0 s 00000 p QOQO 0 0

Hacgina l uhar f piling nerit fc! 5-3-76 CC Q Cc I 0 0 lll r 206-u meshnet 505-u meahnet LCI QOQ CD4 Q P 0 0 0 rc ImIV P 0 w m Atundance Abundance giornoas lrI Cl+I CICl mlCl LI II Ll Lr ' I ~ III +I ~ + II I o rmrmp OO r Imp I OOI 0000 clnPO Cammarid arlphf rods 0.3 + 0.6 4.0 I 3.6 0,01 i 0,02 drCV 4 d 4 d Q p cl I!I CC Calmaaridamphipod epgs 10,0 + 4.4 0.7 i 1,2 Q I IL! Amohipod 0.7 + 0.6 * Captell id amphfoods 0.3 + D.6 cr r trarpsct icold conepode 31.7 + 25. 3 C ~ crclr Or 4 iisrpact ico id eggs 2,7 i 2.5 o v 0 e 400 0 Cslanoid «opepoda 8.0 s 5.6 4.3 + 2.9 4 El elC Ll rl LI rl +I LI Cyclopoid copepods 3.3 + 2.1 s~C lrlvl 0 0 0 Leptostracans 1.3 + 1.5 1.3 + 1.5 g Q Cumaceans 1.D + 1.0 O Isopods 0.3 i 0.6 Annelids 13.3 + 7.5 G.or r o.02 Annelida part» 3.3 + 4.2 * Hematodes 0.7 + D,6 157+211 0.01 + 0.01 0 Decapodlarvae D.7 t 1.2 cl e e Decapodzoea 4.D L 4.4 A ul Decapodmegalops 1.0 t 1.0 t Decapodnauplius 8,3 + 1.4.4 j Crust»ceo nsuplius 11.3 + 12.7 Crustarea ceps 15.3 + 26.6 vo C CC d C frt iped is 1.7 t 2.1 D.D2 i 0.03 s I! 0 Vl I I u O rrr Cirriped is larvae 1,3 L 1.2 D.3 L D.6 Oul c!C Qlv 0 0 4 Cirriped ia juveniles D,r L1,2 a ClCl +I +I Ll Cirriped is parts 8.3 68 r nr PI mrO 0 dI C Cl Q PI o Batantia 0,3 + 0.6 0.01 + 0.02 I 0 4 0C'I Pr iapul id epgs 61.0 4 105.7 Castropods 0.3+ 0.6 Nudibranchs 07+06 0.04 + 0.06 * Divalvia 1.3 + 2.3 4 11O Sivatvia juveniles D.3 i D.6 IV 440' LI * CI Cl &finioae let!i»i juv, 4.7 + 1.5 4.7 i 2.9 Ll +I ClLl Cl I circ!u 1 us 0 7 i 0 6 * rnI 0 I ca * I ttydrozoans 0.3 t 0.6 cvw C!0 W 92 0 0 I 0 Sampletfean 344,0 + 126.4 167.7 t 47.4 0.17 + 0.06 I I I !Negligible ueipht, c 0.01 g. e 4 I V Lt C I d Cl el I la ~ ! ! I V o 4 m v v s n s d CLC4 m»IQ O.O s w5 'dLI n S le4ov c! Ieo ~I le e CI u C I L. e oou m n. m med4 'o v e d u d V V 'd !r C m 4 e C o I 4dgd44 '* 4 4 V LI cl u mrv I11 o O IC e * m s m oI 4 a.! c 4I o u I o 4 R.K. v d 4 el el'a l o d a. 41 u ! L s e I g hsu4 44 4p 4 4 4 X I exp 4mO 0 O I! 0 0 e-

174

175 0 tt 4 0 0 0 0 o 0 o 0 0 0 41 +I +I U U ~ +I tl U 0 0 0ft p 0 0 0 0 0

I ta O 0 0 fS O If92ft aflft dl tt 0 ta I ra W 0 'D tl +I +I +I +I W +I tl ta +I tl tl +I tl IMPORTANTASPECTS OF FORAGINGBEHAV IOR ANOFFEOlhlG MORPHOLOGy I 0 dar I ta IDOL n IN RESOURCEPARTITIONING STUDfES OF F ISMES I 0 afa afalal 0 0 0 0Fl 0 ~I Ll M James Al len 4 U D 'aD 0 Southern Cal I fornia Coastal Water Research Project dl El Segundo, CA 0 Ar waa-4+00 0000 IDIO tl tl ta tl t4 tl ~ I tl +I tl +I 44+I +I I wl f dal O!ltaID 0 ta 0 4 0000 0 WOO The range of food Items that a fish can potent I al ly eat is largely determin- ed by Its foraging behavior and feeding morphology. Resourcepartitioning amongmost coexisting species of demersa I f ishes In southern Cal I fornia ap- ft pears to be the resuii of differences In foraging behavior and feeding morph- I0 0 0 0 0 oiogy Allen, !974!. A description of the forag'Ing behavior of manyspecies' 0 0 o 0 0 +I ~ however, does not occur In the literature, perhaps because this behavior may ~ +I tl tl d U +I seemobvious or unimportant. The objective of this paper Is to emphasize 44 dt '0 CU4c w D0 0 0 0 ft the Importance of foraging behavior and feeding morphologyin resource par- 0 0 0 titioning studies and to describe the types of behavioral and morphoioqical Udl U Information that might apply to these studies. The information I have In- z tl cluded in this paper appears to account for the coexistence of species In 4! t4 ad souther« California fish communities and 'Is further elaborated In DA resolirrp O H O ap ap 0 O partltionlnq mode!of southernCalifornia demersalfish condnu«ittes" I D tl +I +I +I tl +I tl +I tt +I +I I P Allen, manuscript >. m d I t tl 8 I I meir 0 O tt Da0 0 0 afa f< 0 0 O nI va After examining the species that coexist In recurrent groups Fager 1957, 1963! formed from different sets of data and at different levels of assoil.I- tl tion SCCWRP197 3>, I believe that differences amongspecies In Ioraglnq la- 0 tt afa tt ft td havlor or In morphologythat al- UI aal 0 0 0 lows selection of food particles with different qualitiles

176 represent the foraglng behaviorof a f lsh relet lve to thai' of other coexlst- ing or similar species. Themoi phology of anorganism, on tiie other hand, The die! time of foraging is also Important in determining !lie rang» r placeslimits uponits behaviorand therefore often determinesthe behavior items encountered by a f lsh. Two spat i a! ly coexI sting species that -r a!i In for whichthe speciesIs bestadapted. 4s most species are In sameway a s lml lar manner would encounter d I f ferent aod organisms If one specli s Icr- morphologicallydifferent from eachother, the Importantdifferences are ages during the day and ona species forages at night. The t lme of i!i 1liit thosewhilch allow a givenspecies a foragingbehavior that 1sdifferent fram species forages is determined In part by the sense organs that I 1 usi I i lo- that of othercoexisting species s'light morphological differences among cate prey and by the activity patterns of the prey organisms thai il I, .t spatially separatedspecies may be of less Importancethan the spatial adapted ta eat. SpeCieSthat fOrage at night Or In deeper water! rsdf 6»!id separation itself!. either larger or smal ler eyes depending upon whether they locate tlii i r -xistuseful for a! low them a greater mob! I I ty than species without swlmbladders. estimating the arian at ion of tiie 1 siii with respect to the bottomara thase Occasionally species forage In a similar manner ta other caexlstinq spec!i s; speciesthat live entirely on the bottomor In the water column, these species gener a 1I y show differences In structures that a I Inw harn 1 a eat Theorientation of a specieswith respectto the bottomls often associated different types af food part I c les. Differences In feud I ng struc liiri s I ul I with Its search-and-capturebehavior. The major types af search-and-capture Into two categor I es; I ! s I ructures re I at i ng to the s ize af the par c I c un- behaviorfound among demersal fishes includethe fallowing: I! ambushin gulfed and 2! structures relating to the type of parlicle engulfed. he first 2! stalking; 3! pursuing;and 4! searching.To ambuaf means to lie ln ng;walt category can be divided into three major fccding types: I! filter fc~ders, for prey. Anambushnt- expends relatively little energysearching for prey 2! e g Ifers and 3! reducers. Ft'.Ltizr feeders feed primarily on ionrl par-flcies andrelies on the preycomIng near enough to be captured. I'or !his reason, that are very small relative to the mniith size of the fish I.e. nnrh»v!csnv . !, mostprey organisms are rather act!ve, Toetafk meansta approacha prey These f I shes slave the food particles out of the water by means of el iini! i iid organismnear enouqh for pursuitar ambush.A stalkerhas to nxiiendenergy gl I irakers. Engulfera feed on food particles that approximate the size af searchingfor prey I'hat, once ocated,ls quite capableof escape,either the mauth. Large or sma'1 I part I c les can be enguI fed but extreme I y smaI I par- by flight or retreatto cover as in tubicolauspolychaetes!, To pueeue ticles cannot be separated from the water and food particles la! ger t!idn the meansto overtakeand capture. This behaviorIs relatedto stalking and mouth usually cannot be reduced to mouth-size particles. The size nl flir. generallyinvolves a preyorganism that mayescape by flight. Ta search particle engulfed generally increases as the species qrows becauselhn mouth meansta lookfor preyorganisms. 4 searcheroften expends much energy size Increases with the size of the fish; different species, however, stiaw loakingforfood organisms that, oncelocated, are not likely to escape, different rates af increase of mouth size relative ta body iength. Reduneve Oftenthese organisms are hiddenar lievebody structures I.e. shells! that are capable of reducing a large food particle down ta a size that can be en- maymake them Inedilble to most species. In genera , searcliersare oriented gulfed In the mouth. These species often have cuffing teeth I.e. same towardthe bottomwhnn foraging for food parfilcuiariyutilizing sess>!e species of sharks! ar moveabie tooth plates hagfish!. The Incisor-like andInfaunal prey organisms!, while the othersare orientedtoward the water- teeth of the opaleye Gsnelfa isigrfrane! allow It to cut off bits a i" sile calumn utiilzlng planktonic and nektonic prey! or-io both the water co!umn algae. and the bottom utilizing epi auna, nekton, and plankton!. The second cateqory Incliides,prcial izatlnn af the mauih and dier ~ lviI Ii ii-t for particular food Items. This includes I! qenerallsts and 2! sp~rlnlists

I78

9 that are adaptedfor crushingand gr!ndlng hard Items. Mostspec les are con- s ered to be generalistswithiri the rangeof Itemsavailable to them. How- ever, hard itemstaken must be swallowed whole and thus th . I as efficientc en a at u ufillzln i Iz ing this foodsource oas us sper-.les with ese tructurns spec es areadapt natd for crushln th saape g t ieseItems, Crushing structures can exilst In n e the jawj t ee th ra s, same sspeciesof shark!, pharyngealteeth pile perch, !!rma>irzhth Vaccrz! or tootoa hedpiiaryngea I sacs~ ., Stvorrrotetrfoe!.These spec Irm~a 1 ir ht yef in a similarm lar manner m as r!enarallsts but beable to usea dilf >ereritfood resource, Taadequately describe the sort of fr!ragingbehavior that a Ilaws s e coexI sf then re ul- ows species to THE FEEDlh!GBIOLOGY OF THE BAT RAY, >rlyliobrztr.a co>t forrrica en requI res 4 numberof approacliesinc iud i ng InI eerences nce" rom morph- o Iagva ari aridstomach ana I ysi s, wriendirect obsarvatirrn I not avaI !ah le. IN TOMALESBAY, CALIFORNIA pre a on af f i sh staiuac!icont ents wit n respect to t lie food habits of t!ie t 1ah would probabl y also be gr'eat ly facI II tatedI f somrreffart Is d!rected taward deSCriblng tha farag inq be!iaviar Of tiie f iSh. Stephen Karl and Steven Obrebskl University of the Pacific, Pacific Marine Station, Dillon Beach, CA LITERATUREC!TE.D Allen, M.J. !974. F unctionalstructure of demersalfish cr!mmunit les. Annual The bat ray, frfy>,tobrztie oafzforrrt.oo Giii, occurs from Oregon to the Gulf of report far the yearended 30,!«ie 1974. SouthernCalifornia Coastal'Water Ca!lfarnla and Is common In California bays during the spring and summer. ResearchProject, p. 59-73, MacGlnltie 935! observed that during Its feeding activities the bat ray can dig channe'Is up to 'I meter wide, 50 cm deep and 4.5 meters Iong In benthic Fag er , E.W. . . 1957. . Oetermlnatlnn and ana!ysls of recurrent qroups. E I substrates, In Intertidal sand fiats In Tomaias Bay, California, circular 38;586-595. ca ogy pits up ta I meter In diameter and 20 cm in depth are made by bat rays in late summer. >n some areas over 50'$ of the sand flat surface Is covered with Fager'E.W. 1963. ConraunIt iesof organisms,In M.N.Hill ed.!,The sea, bat ray pits. This recurrent seasonal d!sturbance of the substrate due ta yol 2, p. 415-437. John Wiley and Sons, NY bat ray predation on benthic coimnunit les may be Important in affect lrig their structure and faunistlc composition. In preliminary studies of the effects Hobson>obson,E.S. 1968. Predatory behavioraf someshare 1 aliasi In the Gulf af of predatlan on benthilc corrmrunlties In Tome!ca Bay, we were interested in CaI Ifornla. U.S. F lahWild!, Serv.Res. Rep. 73, 92 p. obtain!ng Information about changes In diets af bat rays In relation to size. Souther'nCaI ilfern la CoastaI Water Rasear chProject. 1973. The I colagy of Stomach contents from 422 bat rays were obtained ln Tomales Bay during the theSauthern Ca!I fornla BIght; ImpI lcat lons for waterqua I ity management. annual Shark and Ray Derby on July 12-13, 1975. Data from this sample are TR 104, reparted here. AII specimenswere caught by hook and line In TornalesBey. SouthernCalifornia Coastai Water Research Project 531 p. The rays were brought In live and weighed to the nearest half pound wlltiin 1 0 hours or less fram the t I me of capture. The rays were evl scerater> r!n arrival and stomach contents were removed and preserved in $ forma!ine In seawater. After 3 days the stomachcontents were transferred Into 70$ Contr!bution No. 79 fromthe SouthernCal I fornlaCoastal Water Research Project. ISapropyl alcoho'!. All diet ItemS were Identified within 3 WeekS al the col- lection time. The length and width or diameter In cylindrical organisms! of ali !dentlfiable diet items were measured to the nearest millimeter. The most commonlyused baIt for catching rays were frozen anchovies, squid and the echlurold, Ureohia oaripo. U. oarrpo used as balt that was found in the stomach was easily differentiated from that eaten alive by the rays. The wormsused as balt were always flat, having lost their natural, rotund shape, and were also tarn or punctured and muchpaler In color. U, coupo eaten alive main- tained their red or bright pink coloration and live shape and never sliowed signs of tearing or perforation. Surprisingly, no partially digester! U. coupe were ever observed. Manyof the orqanisms found In the ray stem!re!is were o dlslntegrated as to preclude their identification or use In as! imiles of their contr>but ion by weight or volume to the total dirt. Somespecies,

16! 180 such as the pol ychael ps 5br!ne!'eretetr'au!v! >Hercof ipr! Indistinguishable and their cour>l, were combined, A few squid ar squid frag- ments were present in some rays, but since squid were used as >sit and could not be dl fferent lated I lkn V. caupo, they were not counted. TI>e clams Presue >!uttaZZii and Snaidomuerutalli were ldenl i f i ed ej fher f ><>m shel I fr ag- ments or from siphon 1 ips r!lo and places of the fool, Livo clams col- lected in TomalesBay were examinedlo obtain diagnostic criteria Ivr the ITZM5 5! OM5«5 soft parts, We are indebted to the Palaluma California> !utdoar sr»en's Club 10 ~ Iris! for their generoushelp in providir!g for the cvlleclian of thi, ,.!rnple. Ray 'EM5 Richardsonhelped In manyways with organization and callectior! of samples, 515ISS<> Wealso thankPacific MarineStation graduatestudents wha hell>ad < ollect camper ison with the largestIs>pale whi!ez'eis tetraura!r 2 14; Vzechie caupo, 99; Saaidowee nuttalli, l91; Vpogebia pugctteneie, 74; Priapulus nudus, 65; 2'reeue 40 iQ nuttalli, 34; Ca>seerepp. TC. grani Lie and C. anthonyi! 21; Zfemigrapeuenudue, 12; Lietriolobus pelodee, 3; l>facomasecta, 2; 10 tacoma naeuta, I; and Stylatula elongata 50 The third edition of Ligh'I''s Manual was used to Identify the above Invertebrates Smith lir Pr!spplprsrpss and Carlton, 1975!. K I 0 Ifo s igni f icant correi el lons between prey size 10 and ray size were found for individual species 10Se 5000 Se 50 0 10 00 50 r>0 50 or the total suilte of dilet items combined, 0 10 50 50 40 50 lk l-lowever, examination of frequency distribu- 5005>SMyr 5!0» «0" e0fi'llsM wz5 5 050II P tionss of pt oporl lans of particular items in the diet of weight groups of rays or by per- cent of stomachs containinq a particular Figure 2. Proportionsof food Items in size groupsof Hyliobatie rali for rri ',!s 0 0 10 203040 5060 follow'Ing trends ln bat ray diets. Bath percentagesof stomachconte'Ining particular Itemsin the weiqhI Vzechis caupo and Treeue nuttalli Increase group Indicated. KILOGRfiIIIyf EfG f17 In Importnnce with increaslnq bai ray size, GROUP whi la P!iapulue rrudue <1ndpal ychaei es drzcI"pa in irnportanr.e ir> la! ger rays. PoI ychaetpeep F i 0<>re I We I ght d I" tr I li! ' pear I o have e ency ol occurrence I ir>n!i of bat rays c I assroi,ebia pugetteneie

l83 I82 remains unchanged, its frequency In stcmachs Increases «11h size. No clear trend Is apparent far Satidomuenut talli or Cancer epp. and the In his szudyof bat ray dIets In TamalesBay, Ridge 963! combined data for Fietrolobue and lfemigrapeueare Insuf f lc lent to Indlc >te any weightclasses so asto haveequal numbers of Individualsln each weight trends. The data suggest that there might be a relatively abrupt change class. Thus, his smallest size group Includedrays up to I kg In weight In diet In female rays above 30 kg in weight. Rays above this critical andthe largestgroup combined rays between15 and 50 kg, This procludes size appear to special lze In feeding on Treaz>e>z»ttal li and Ureohie comparisonsof our datawith h'Is f lndlngs.However ~ his largestsize eaupo, two of the largest and deepest burrowing organisms In TomalesBay groupup did showan increasein occurrenceof largerclams, shrimp and echlurolds. 'Hareover,Ridge i dentl f ied over 66 speciesof benthie c benthic communities, organismsIn ray stomachs,with 17species of polvchnefesIdentifiable to Comparisons of male and female bat ray diets for spec Imens 15 kg In genus.Our much shorter list af diet Itemsis probablydue to our u ing weight or less were made using data on the numbers of stomachs containing a sampletaken on 2 daysduring the yearwhile hfs samplesoccurred different diet items. The data are shown In Table I. The Items were throughoutthe year. In addition,we were obliged ta userays kept olive ranked in order of decreasing abundanceand a spearman rank carrelation upto 10hours allowing for digestionof manyitems before preservation coefficient was calculated. This was not significant rs = 0,29!. On while Ridge preserved stomachs immediately after capture, the basis of this small amount of data we conclude te ntatlvely that diets of male and female bat rays below 15 kg In weight are Thereare na estimatesof the size af the feedingbay ray papu>tie»s in not different. TomalesBay. Of 90 rays taggedat the beginningof June, 1915 in The foregoing Information suggests that as Jf!jliobatie ealifornioa Increases TamalesBay ~ ane wasrecaptured In the bay 2 weekslater end2 we>e In size, larger, deep-burrowing organisms becomeIncreasingly important captvredIn SanFrancisco Bay, 40 miles southof TamalesBey, I mavin in the diet. The species that becomevery commonln rayS greater than later. These results are useless for population size estimation nnd 30 kg In weight, Ureoftieoawpo and Treeewe n»ttalli, are both deep- suggestthat h lqhmigration rates would not allow effective mark-re capture burrowlng organilsms. U. eaupo occurs In U-shapedburrows downto I meter estimates of abundance. Anecdotal obse>vations by TamalesBay fisherr>en In depth and T. >tuttalli Is knownto burrow dawnto 0.5 meters Fitch, indicate that schoolsof rays numberingIn manyhundreds can samoiimes 1953!. Wecan only speculate about the reasons for this change. Perhaps be observedIn shallow waters. Scmebelieve that manytens of thousands there are mechanical consequencesassociated with large size that permit of rays might be present ln late summer.The extensive disturbance large rays to burrow deeply and feed efficiently on larger benthic dueto ray feedingIn Intertidal areas-suggests that subtidalpredation organisms. mightbe equally high. About18$ of our sampleconsisted of raysqrea ler th 30 k ln we'ight. Largehf. califor»ioa havebeen observed by divers Table I. Frequencies of food Items in stomachs of male and female off Catalina Island, CaI ifarn la . Our I ng the I r feeding act i vll I os >ey Myliobatie oalifornioa 15 kg or less ln we'Ight excavatedeep depressions and attract manyother fish which feed on the organismsthus exposed R. Schmltt, Departmentaf BiologyUCLA!, There- fore, It 'Is likely that bat ray feedingIn TamalesBay might eisa muke morefood ava'liable far other speciesof fish. Duringshallow wate>dives Food S ecles Females Hales In TcmalesBay we observed that Urea!>iecaupo burrows were frequently used hidingplaces for sma!Icrabs, particularly lien>igrapeue epp. Thissuggests Llstrolobvs elodes that bat raysmight also Indirectly regulateabundances of smal'I crabs by affecting the abundancesof Ureehie. Theseobservations suggesi that Saxidomus nuttaiil perlmetal stud'lesof effects of bat ray predatlanon benthicco»Inunlty structure should Include studies of Indirect effects on other pre n or 21 populations. HemI ra sus nudus L ITERATURE C ITED U ebla u ettensls FItch, J.E, 1953, Commonmarine b'Ivalves at Callforn la. Fish. BulI, Palychaetes 16 No. 90. State af Ca!Ifornia, Dept. of Fish and Game, 102 pp. ~Uh i MacGlnit le, G,B, 1935, Ecologicalaspects af a Cali fornlamar'ine estuary. Amer. Midi . Nat. 16:629-765. Tresus nuttalf1 Cancer s~.

184 185 RIdge,R.N. 1963. Foodhabits of the bai ra rom arnees Bay,Cal lfornla. Master'sThesis, Unlversliy of Callfornla, Berkeley. 56 pp. Smith,R, I. andJ.T. CarI tan eds.! . 1975.Light 's Manual;In fert fdel invertebratesof the Central Cal I fornlaCoast. Third Edi flan, UnIver sf ty of CalI for»laPress ~ Berkeley, 716 pp,

D ISNESSION: SESSION5: INTERPRETATIDN AND RESULTS

Immediately after Steve Obrebskl's presentation, Jack Wordasked about the terrebel ld worm used In his studies. Oberbskl said that It was Kupolmniaczeecentie and noted that the guts af the warmswere always paiatable; It was either the body or tentacles that weren't palatable. And with other terrebelfds, if the body Is protected then only the tentacles are unpalatable, and usually 'lt lives In a hard tube and has a very rapid escape response. Obrebski afso mentionedthat his responseto the question, "Why in the devil doesn't somethingget eaten when ft's very abundant7" especially If It's exposed and active, Is to get scmeoi the critters and the fish, starve the fIsh for 5 days, and put some of the critters 'In the tank; If they don't get eaten, then they are unpalatable. Gary Smith said ',hat, in analyses of diet overlap and potentla'I campelillo», the key requirement is to Iaok at the food s >pply. Thus, without a food 11mitatlon there's na competition, but the abundance and availability of food items are very difficult to measure. Obrebski replied, "I don' I th Ink that food Iimitat'ion, per se, Is the criterion because, as yau know from looking at Ivlev's curv~es, he Issue Is the maxlmlzatilon of feeding ef f Ic I ency, Then, If a species Is feedI ng with a competitor that Is s Imuitaneaus ly reducing the dens fty of the organ fsms being fed upon, such that lts efficiency decreases

IBG I87 Askedhow he dughales In sedimentto dupI icate those created by rays, planktonpump underwater, but that they couldnot detectany organl Glenn Van Blar1com replied that he just used his hands In the samemanner re ac ting ng to o athat as such. BabFel ler suggestedIncreasing the f II terinq that the rays usedtheir "wings," Ife wasalso askedwhether swimming ef f iciency to prevent c logging! by Increasingthe surfacearea of ethe activity hadany ef'lect on canwiun!Cvsampling areas, VanBiai leamreplied mesh relative to the mouth opening. that lf definitely was a problem and worth worrying about. IIi tried to confine h Is swinimlng act lv It Ies to cartaIn carr I ders and anI y r eachout JohnElf ison questionedthe val fdlty of Obrebskl'suse of the teim of these In order to minimizedisturbance. JohnStephens asked "preference"to implythat the f ishwas, ln someway, passing up ane food Van BlarIcom about the frequency of -related dist urhnnce In fhat Item for another, "whenconsider'Ing diets of 2 different fish, you really habitat. It apparently Is frequent during the winter, thaughrare in the needto look a lot c'loser at the benthosof the water column,wherever summer. John Fiiisan asked about related sand transport and Vari Blarlcom their food Is, before you use this term . . ." He suggestedthai wehave said that they had stakes placed In the study area and iiiese rtldn't to be morecareful In use af "preference," "selectivity" and termsof showmuch var ! atI qn; when I f d Id occur, It appeared to b ~assoc I ot ed w Ith that nature, Obrebsklagreed that his use of the termwas Imprecise. th occurrence of major sforms, His data showedthat In someinstances there is similarity in faad Itimi-, and sometimesthere Is considerabledissimilar'Ity. Hewent an to cite Si S lmenstadasked whether cert;.In areas had higher densl I fes of holes, a paperon bluegill predationon Daphrri.awhich was relative ta this Van Bier leam repi fed Chef Chere was no indication of any - referred problem;1 hepaper addressed some theories about what It is thai I oraqei s areas ~ I .e., a eel ai Ive I y randem act iv 1ty, optimize,I.e. whatsize rangeof food itemsls beingoptimized. One o fepo the points smmade In I'hepaper was that theseC lsh,when presenter> ~ Iiii Obrubski asked I f there was any indicaf loii of how much of the reer el fment a new, dl fferent size rangeof organisms,could almost InstantaneousIy ta the disturbance s I tes was sett I ament or mi grat ion; Van filar iran sa Id adapttheir behaviorso as to optlml ze their foragingIn this canfext, that, although they werejust generating that data, It appearedthat This Illustrated whywe shouldn't reaily Interpret anythingunless wr've at least for crustaceans and paI ychaetes, It was via migration. hada chanceto seethe fish da somethingto diet Itemsoffered In e tunk or, optlmally, in a natural situation. Thegenera I discussIon started wlfh questionsaf Slmefistadreqardlng performance of the plankton pump. John Slbert wondered how much of the ElI fsonasked I f It wasn'tmore of a questionof avaI lablI ity, Obrebskl pumpsample camefrom outside the I-m sampling ring. Simenstadsaid suggestedthat It's undoubtedlymore complex than that lt ls quife that the divers wha manipulated the suction cone had obser ied a few possiblethat organisms,If they're offered elternat'IveItems, «I I I animals being sucked from outside the sarnpllng area and that they were switchto optimizeboth an itemsand size classesand their behaviorwill considering going to a cylinder In order ta be!ter isolate Ihe bottom also be affectedby the presenceor absenceof othercompeting speci~a sampling area and prevenf lafera! contamination. The larger question Is through behavtorai Interactions. the percentage of the total available eplbenth'Ic plankton which is sampled In a single 100 gal. 200 gal. 300 gal etc. sample and whether Alongthe samefine, GarySmith also wonderedabout the useof food organisms are differentlally available fo the pump. Sibert also asled compositionas ev'Idenceof competition,optimizatilon or partltlonlnq whetherthe I -m2ar ea samplewas subsarnpl ed; S lmensfad replied that three strateg'lesof predatoryspecies, Hethought that therewas a good I/10 subsamples,with replacement, were used to characterize the whole chancethat, If food ls abundant,It's Just a result of chanceencounters sample although It was a difficult tradeoff becauseyou need enoughto of foodparticles, not partitioning or selectionbut rathermorphalaqles, provide the necessary biomass estimates but, by that time, you' ve almost behavior, etc. Obrebsklsaid that, If you postulate a randomencounlei got too many to count. modelto explainthe abundanceof a particular foodor an organism,then givena fixed morphologyand forag I ngbehavior, there « III st I II be The questionwas raised about the camparabfI Ity af I hepump samples with consequencesas the amountof a particular Itemwill dependupon a core samples. Slmenstadsaid that they hadn't madeany direct camparfsans variable encounter rate. Thus he suggested that once you !now these yet, especial ly since not many investigators had resorted ta a sieve th I ngs,on I y thencan you make statements about compet ft ion . Jim A IIon size as small as 200 u. Wordrecanmiended that they not be toa concerned postulatedthat whenfood Items are In verylow density, then It probably with different penetrations of the suction "field" In various substrates Is a matterof preyavaliablifty but, If you've gat a largenumber of becausemost of the organisms of concern occur In the upper few centi- species,representing a variety of escaperesponses, then It ls of same meters anyway. advantageto a predatorspecies to madlfyIts behaviorsuch that It optlmlzes Its predation on certain food Items. Wordalso askedwhether or not the pumpsystem In operation madeany noise underwater; Slmenstad said that the divers could hear or feel! the Stephensrecounted his experiencesobserving Rhacaehilue ueaea to gasoline engine powering the pumpsa It was Impossible to say if 'the determinewhether ! t wasa grazer or select ive feeder. BecauseI 1 Is ~ne pumpitself wasnoisy. RobilnLeBrasseur commented that they can fiear their of the least active anddoes the mostsearching, a diver can actually

IBB 189 observe eye movements. He described how they makea numberof PARTICIPANTS approachesto food I teaiis before f inn I Iy consumingone such that you can count bites/minute. Whenhe eventually lookedat their diet, they were Al I en, Merri I I James Cong eton, Jiia largely taking sraali molluscs. O1horspecies which approache

190

191 Stainer, Richard G. Healey, Mike Lev lngs, Col ln Obrobskl, Steven University of the Pacific Department of Fisheries Fisheries and Marine Service Environment Canada and Wiidl'Ife Bioiogilcai Station Fisheries and Marine Service Pacific Marine Stat!on Dillon Beach' CA 94929 Oregon State University Nanaimo, B.C. Biological Station Box 352 04! 758-5202 4160 Marine Drive DepoeBay, OR 9734! West Vancouver, B.C. Z7V IN6 Paulson Alan Hostou, Howard 04! 926-6747 Institute of Marine Sciences University of Alaska Stephens John Department of Fish and Wlldllte Department of Biology Oregon State University Levy, Dave Fa I r banks, AK 9'! 701 907! 479-7671 Occidental College Corvalils, OR 97331 Institute of Animal Resource Ecology l600 CampusRoad University of British Columbia Ph'I I I i ps Anton Los Angeles CA 9004 Jaenlcke, Herbert Vancouver, B.C.

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