Mercury Testing of Sport/Food Fishes within Humboldt Bay · 2018-05-21 · Mercury Testing of Sport/Food Fishes within Humboldt Bay Project Purpose and Need Mercury advisories have

MercuryTestingofSport/FoodFisheswithinHumboldtBay

FinalReport

April2018JenniferKalt,HumboldtBaykeeper,Arcata,CA

RossTaylor,RossTaylor&Associates,McKinleyville,CA

PreparedforHumboldtBaykeeper600FStreet,Suite3#810

Arcata,CA95521

FundedbyCaliforniaEnvironmentalProtectionAgency

EnvironmentalJusticeSmallGrantStateofCalifornia

Disclaimer:ThestatementsandconclusionsofthisreportarethoseoftheGranteeandnotnecessarilythoseoftheCaliforniaEnvironmentalProtectionAgency,itsemployees,ortheStateofCalifornia.TheStatemakesnowarranty,expressorimplied,andassumesnoliabilityfortheinformationcontainedinthesucceedingtext.

HumboldtBaykeeper–MercuryTestingofHumboldtBaySportFishes–2018 Page1

Acknowledgements

HumboldtBaykeeperwouldliketothankthemanypeoplewhocontributedtotheHumboldtBayMercuryAssessment:

RossTaylorofRossTaylorandAssociates:Consultingfisheriesbiologistandavidfisherman,Rosscontributedtoallaspectsoftheproject,includingstudydesign,processingsamples,dataanalysis,reportwriting,andoutreachtosportanglers;

JasminSegura,HumboldtBaykeeper:Anglersurveys,Spanishtranslationandinterpretation;

TedHernandez,VincentDiMarzo,TimNelson,andPatriciaTorresoftheWiyotTribe:Inputonsamplingdesignandrecommendations,harvestingclamsamples;

MitchFarro,DarrenWard,PatMoorhouse,DougEpperley,IshanVernallis,ToddKraemer,andMikeWilson:Volunteerfishermenwhocollectedmostofthesamplesanalyzedforthisstudy;

PhilGlenn:Charterboatcaptain;

MaryAnnHytkenandallofherstudentsandassistantsatEnglishExpress,anon-profitEnglish-as-a-SecondLanguageschoolinEureka,CA;

MikeBuettner:Graphicdesign;

CoastSeafoodsCompany:Oysterssamples;

CEBAMAnalytical,Inc.ofBothell,Washington;

themanyanglerswhopatientlyansweredourquestions.


MercuryTestingofSport/FoodFisheswithinHumboldtBay

ProjectPurposeandNeed

MercuryadvisorieshavebeenissuedformanymajorwaterbodiesinCalifornia,includingcoastalareasofNorthernCalifornia.HumboldtBayiscurrentlydesignatedasanareainneedofasite-specificfishadvisory(Smithetal.2016).In2012,theNorthCoastRegionalWaterQualityControlBoarddeterminedthatHumboldtBaydidnotwarrantlistingformercuryimpairmentunderCleanWaterActSection303(d)basedonmusseltestingdoneinthe1980s(NCRWQCB2012).However,thatsameyear,areportwasreleasedshowingthatLeopardSharkfromHumboldtBayhadthehighestmercurylevelsinastatewideassessmentofcontaminantsincoastalfish(Davisetal.2012),indicatinganeedforfurthersamplingofcommonlyeatenfishcaughtinHumboldtBay.

Background

FishconsumptionisthemajorrouteofmethylmercuryexposureintheUnitedStates(ATSDR1999).Formanyyears,mercuryadvisoriesfocusedprimarilyonwhichfishtoavoid.Aresultofthisapproachwasthatmanypeoplesimplyeliminatedfishfromtheirdiets,especiallypregnantwomen.

Therearemanyhealthbenefitsofeatingfishthatislowinmercury,PCBs,andothercontaminants.Fishishighinproteinandlowinfat,andisanimportantsourceofomega-3fattyacids,whichsupporthearthealthandbrainfunctions(Silbernageletal.2011).Inrecentyears,concernshavebeenraisedaboutgenericfishadvisoriescausingharmbyencouragingpeopletolimittheirfishconsumption,therebylimitingthebeneficialeffectsofeatinglow-mercuryfish(Verbrugge2007).

Methylmercuryisapowerfulneurotoxinthatcancauselossofcoordination,blurredvisionorblindness,andhearingandspeechimpairment.Atlowerlevelsofexposure,moresubtlesymptomsinadultsarenumbnessortinglinginthehands,feet,and/oraroundthemouth.Developingfetusesareparticularlysensitive,andcanexperienceslightdecreasesinlearningabilities,languageskills,attentionand/ormemoryfunction(Silbernageletal2011).

Methylmercuryaccumulatesinthebody,andmagnifiesinlarger,olderanimalsthateathigheronthefoodchain(Davisetal.2012).Butreducingmercuryexposurefromfishconsumptioncanlowerthemercurylevelsinbloodandhairsampleswithinafewmonths(Bose-O’Reillyetal.2010).Thisisespeciallyimportantinformationforwomenofchild-bearingage,sincetheycanreducetheirbabies’mercuryexposurebyeliminatingfishwithhighmercurylevelsfromtheirdiets.


Themostvulnerablepopulationsarepeoplewhoeatalotoffish,includingrecreationalandsubsistencefishermenandtheirfamilies,tribalmembers,HmongandotherAsianresidents,Latinoresidents,andpeoplewithlowincomesthatfishtofeedtheirfamilies.Anothergroupatriskincludespeoplewithhighincomeswhocanaffordtoeatalotofexpensivefishsuchastuna,swordfish,andsushi.Thereareincreasedconcernsforpeoplewhomayconsumemanymealsfromonelargeanimal,suchasrecreationalandsubsistenceuserswhofreeze,smoke,orpressurecookandcanfishtoeatallyearround.

Mercuryisanaturalelementfoundinsomerockandsoil.Humanactivities,suchasburningcoalandtheuseofmercurytominegold,alsoaddmercurytotheenvironment(Smithetal.,2016).Atthistime,therearenoknownlocalsourcesofmercuryintheHumboldtBayarea.MercurywasusedinhistoricgoldminingintheKlamath,Trinity,andRussianRivers,butisnotknowntohaveoccurrednearHumboldtBayorintheadjacentEelandMadRiverwatersheds.ThemercuryintheHumboldtBayregionisthoughttooriginatefromcoal-burningpowerplantsinAsiaandelsewhere,whichisemittedintotheatmosphereanddepositedacrosswesternNorthAmerica.ArecentstudyfoundthatcoastalfogdepositsmercuryathigherlevelsthanrainwaterinCentralCalifornia(Weiss-Penziasetal.2012).PreviousStudiesintheRegion

Aspreviouslymentioned,a2012reportfoundthehighestlevelsofmercuryinCaliforniacoastalwatersinHumboldtBayLeopardShark(Davisetal.2012).TheaveragemercurylevelsintheseLeopardSharkfromHumboldtBaywas1.66partspermillion(ppm)–morethanthreetimesOfficeofEnvironmentalHealthHazardAssessment’s(OEHHA)“donotconsume”levelforwomenunder45andchildren(KlasingandBrodberg,2008)andmorethantwentytimestheadvisorylevelusedtodefinesubsistencefishing(GasselandBroberg2005).Onastatewidelevel,surveyresultsindicatethatthereissignificantmercurycontaminationincoastalareastocauseriskstohumanswherevertheycatchandeatlong-livedpredatorfish(KlasingandBrodberg,2008).

In2005,HumboldtBaykeeperteamedupwiththeWaterkeeperAllianceandtheEnvironmentalQualityInstituteatUniversityofNorthCarolina,Ashevilletosamplethreeimportantlocalfishspecies:ChinookSalmon,AlbacoreTuna,andLingcod(Evenson2006).TheChinookSalmonwerecaughtinthePacificOceanjustwestofHumboldtBay.TheAlbacorewerecaughtapproximately90mileswestofEurekaandrangedinsizefrom22to31pounds.LingcodwerecaughtoffthecoastofCapeMendocino,relativelyfarfromanyknownindustrialsourceofmercurypollution,andthesefishrangedfrom6to25poundsinsize.ResultsofHumboldtBaykeeper’spreviousmercurytestingareincludedintheResultssectionofthisreport.


Methods-SpeciesSelectedforTesting:

FortheHumboldtBayprojecttheprimarycriteriaforselectionoffocalfishspeciesincluded:

• ThespeciesiscommonlyfishedforinHumboldtBayandkeptasafoodsource.• ThespeciesresideswithinHumboldtBayforasignificantpartoftheyear.• Thespeciesisrelativelylong-lived,thusmoresusceptibletobioaccumulationoftoxins.• Thespeciesisalreadyassociatedwithmercuryhealthadvisorieswithincoastalwaters

ofCalifornia.• Thespeciesisanimportantindicatortostatewidetrackingofmercurylevelsduetoits

widedistributionandabundantpopulations.

Thefishspeciesmeetingthesecriteriaincluded:

LeopardShark(Triakissemifasciata)–isaspeciesofHoundshark,commoninbaysandestuariesalongthewestcoastfromOregontoMexico.Theyaremostlyfoundinshallowwater(<4metersdepth)andoftenforageonmudflatsduringincomingtides.Fooditemsincludeclams,shrimps,crabsandbonyfishes.MostLeopardSharkshavehighsitefidelityandtendtoremaininarelativelysmallgeographicarea,whichhasledtogeneticdivergencethroughoutthespecies’distribution.LeopardSharksarecaughtbybothcommercialandrecreationalfisheries,forfoodandtheaquariumindustry.Whenhandledandprocessedcorrectly,themeatisconsideredexcellenttablefare.LeopardSharksareslow-growingandlong-lived,withfemalesreachingmaturityat10-15yearsandanestimatedmaximumlifespanof30years.LeopardSharksareknowntohavehighlevelsofmercury(Davisetal.2012).ThisspeciesiscommontoHumboldtBay;oftenupintotheMadRiverSloughandtheArcatachannelintheNorthBay.

BatRay(Myliobatiscalifornica)–isaspeciesofeagleray,commoninmuddyandsandysloughsandbaysfromOregontotheGulfofCalifornia.Batraysareeuryhalineandcantolerateawiderangeofsalinities.BayRayscangrowupto200pounds,butmostfishaverage20-30poundsinweight.Commonfooditemsaremollusks,crustaceansandsmallfishwhichtheyforageoffofthebottom.Theserayscanalsodigdown20cmtoexposeburiedpreysuchasclams.BayRaysareapopularsportfishinbayandpierfisheriesduetotheirlargesize,fightingcapabilitiesandarealsocommonlyeaten.Thewingshavelargeamountsofmeatthatmustbecleanedandprocessedquickly.Maximumlifespanhasbeenestimatedat20to25years.BatRaysareknowntohaveelevatedmercurylevels(Davisetal.2012).ThisspeciesiscommonthroughoutHumboldtBay.

CaliforniaHalibut(Paralichthyscalifornicus)–isalarge-toothedflounderspecies,distributedfromWashingtonsouthtoMagdalenaBayinBajaCalifornia.Thisflounderspeciesiscommoninbaysandnear-shorewatersandisanextremelypopularsportfishduetoitsexcellenttablefare.MostadultCaliforniaHalibutresideinwaterdepthslessthan30meters.Juveniles


commonlyrearinprotectedbaysandadultsopportunisticallyinhabitbayswhenforagefishareconcentrated,suchasinHumboldtduringthesummerof2016.Californiahalibutcangrowupwardsof50pounds,butmostsport-caughtfishareinthefiveto20poundrange.UsinglightlineandlivebaitismostproductivewhenfishingforCaliforniaHalibut.Femalesmatureataboutagefourtofiveyearsandtheirmaximumlifespanisapproximately30years.CaliforniaHalibutareknowntohavemoderatelyelevatedmercurylevels(Davisetal.2012).Aspreviouslymentioned,thisspeciespresenceandrelativeabundanceinHumboldtBayisinfluencedbyavailabilityofforagefishsuchasanchoviesandsardines.CaliforniaHalibutweretargetedheavilyinHumboldtBayduringthesummersof2016and2017.

Lingcod(Ophiodonelongatus)–isthelargestmemberofthegreenlingfamily,Hexagrammidae,andisdistributedalongthewestcoastfromtheGulfofAlaskasouthtoBajaMexico.Theyaregenerallybottom-orientedfishassociatedwithrockyreefsindepthsof20to100meters.Lingcodarelargelynon-migratory.Theyareapopularsportfishduetotheirlargesize,aggressivenessandexcellenttaste.Lingcodcanexceed100poundsinweight,but10to30poundfisharemostcommon.Femalesmatureataroundage3to5yearsandcanliveupto20years.Maleshaveamaximumlifespanofaround14years.Lingcodareknowntohavemoderatelyelevatedmercurylevels(Davisetal.2012).InHumboldtBay,Lingcoddistributionismostlyrestrictedtotherockyhabitatofthejettiesandfisharecaughtbybothshore-basedandboatanglers.

ShinerSurfperch(Cymatogasteraggregata)–isthemostwidelydistributedoftheSurfperchspeciesinCaliforniawaters.ShinerSurfperchprefercalmwatersofbays,oftenassociatedwitheelgrassbedsandaroundthepilingsofdocksandpiers.ShinerSurfperchcanalsotolerateawiderangeofsalinitiesandcanbefoundinthelowerreachesofcoastalrivers.Thesefisharenotlong-livedanddonotfeedhighonthefoodchain,thusprevioustestinghasshowntheirmethylmercurylevelstoberelativelylowwhencomparedtootherspecies(Davisetal.2012).ShinerSurfperchwereincludedinthisstudybecauseitisapopulartargetspeciesofdockfishermen,iskeptforfoodandpreviousstudieshaveshownthisspeciestobethebeststate-wideindicatorspeciesforbaysandharborsbecauseofitswideandcommondistribution(Davisetal.2012).

Thesefivespecieswereoriginallyselectedasthestudy’sfocalspecies,yettheexactlistofspeciestestedwasmodifiedoncethestudywasunderway.Speciesaddedtothestudyincluded:WalleyeSurfperch(Hyperprosoponellipticum),Jacksmelt(Atherinopsiscaliforniensis),BlackRockfish(Sebastesmelanops),Horseneck(orFatGaper)Clam(Tresuscapx),PacificLittleneckClam(Protothacastaminea),MarthaWashington(orButter)Clam(Saxidomus

gigantea),andOystersfarmedinHumboldtBay.


WalleyeSurfperchweresampledinsteadofShinerSurfperchbecausewewereunabletolocateanyconcentrationsofShinerSurfperchinHumboldtBay,whereastheWalleyeSurfperchwereabundantarounddockpilingswhereshore-basedanglerswerefishing.ThesedocksandpilingswerealsofrequentedbyJacksmelt,sothisspecieswasincludedformercurytesting.BlackRockfishwerecaughtwhilefishingforLingcodalongHumboldtBay’sjettiesandwereincludedinthesamplingbecausethisisatargetspeciesforpeoplefishingfromthejetties.ThethreespeciesofclamswereincludedbyrequestoftheWiyotTribe,whosemembersfrequentlyharvestclamsfromtraditionalsitesinsouthernpartsofHumboldtBay.Thefarmedoysterswereincludedbecauseoftheircommercialimportancetothelocaleconomy.

Methods-FishSamplingandProcessing:

FishsamplesfortheHumboldtBaymercurystudywerecaughtwithsport-fishingtackle,followingcurrentregulationssetbytheCaliforniaDepartmentofFishandWildlife(https://www.wildlife.ca.gov/regulations).Wereviewedfederalandstatecollectionmethodologieswhichstressedtheimportanceofproperhandlingandpreparationoftissuesamples,thussamplingwaslimitedtoapre-screenedgroupoffishermenthathadpreviousexperienceinbiologicalfieldsurveysanddatacollection.

MethodsusedtohandlefishandpreparesamplesfortestingwereconsistentwithmethodsdescribedintheEPAdocumenttitled,GuidanceforAssessingChemicalContaminantDatafor

useinFishAdvisories.Volume1:FishSamplingandAnalysis(U.S.EPA2000).However,onedeviationfromtheU.S.EPAmethodswasnottestingcompositesamples(amixtureoffleshfrommorethanonefish),becausetheuseofarangeofsamplescollectedbyvariouspersonsatvarioustimesandlocationswaspotentiallynotsuitableforcompositetesting.Also,testingofcompositesamplesrequiresahigherlevelofqualitycontrolinobtainingandhandlingsamples,aswellasamorerigorouschainofcustody.Theexceptionwastheshellfish;compositesampleswereanalyzedforallfourspeciesincludedinthestudy.

Oneofthemostimportantaspectsofthisprojectwashowfishwerehandleduponcapture,asexemplifiedbythefollowingparagraphintheU.S.EPAdocument:TheprimaryQA

considerationinsamplecollection,processing,preservation,andshippingproceduresisthe

preservationofsampleintegritytoensuretheaccuracyoftargetanalyteanalyses.Sample

integrityispreservedbypreventionoflossofcontaminantsalreadypresentinthetissuesand

preventionofextraneoustissuecontamination.


Thesesteps,asrecommendedbytheU.S.EPA,werefollowedwhenhandlingandprocessingfishcaughtinHumboldtBayfortesting:

1. Allfishkeptforatissuesamplewerecaughtaliveandwerefreeofcuts,lacerations,tumorsandotheropenwounds.Wereleasedanyfishthatappearswounded.Allfishthatwerenotoflegalsizewerealsoreleased.

2. Allequipmentusedformeasuring,holding,processingandstoringfishand/ortissuesampleswerecleanedwithdetergentandrinsedwithdistilledwaterpriortoprocessingeachfish/tissuesample.

3. Toavoidcontaminationwithmeltingiceincoolers,sampledfishand/orfiletswereplacedinwaterproof(zip-lock)bags.

4. AlthoughtheU.S.EPAdiscouragesfieldprocessingoffish(i.e.filletingandbagging),whenthiswasdone,extracarewastakentoavoidcontaminationwithanysourcesofgasoline,diesel,oilsandgrease.Allknives,cleaningboardsandgloveswerethoroughlywashedbetweenfieldprocessingoftissuesamples.

5. Individualfishoftheselectedtargetspecieswererinsedinambientwatertoremoveanyforeignmaterialfromtheexternalsurface.Largefishwerestunnedbyasharpblowtothebaseoftheskullwithawoodenclubormetalrod.Thisclubwasusedsolelyforthepurposeofstunningfish,andwascleanedtopreventcontaminationofthesamples.

6. Oncestunned,thefish’stotallengthwasmeasuredincmormm(Figure1).ForBatRay,measurebodylength,lesstail/whip.Wholefishwereweighedwitheitheradigitalhangingscaleoradigitaltrayscale.

7. Photosweretakenofeachprocessedfish.Atleastonephotohadsomethinginthephotoforscale(suchaspersonormeasuringdevice).

8. Fieldprocessingwasdoneimmediatelyandfilletingwasconductedbyanexperiencedfisheriesbiologist.Priortofilleting,hands(orgloves)werewashedwithsoapandrinsedthoroughlyinambientwater,followedbydistilledwater.Specimenscameintocontactwithnon-contaminatingsurfaceonly.FishwerefilletedonaPolytetrafluoroethylene(PTFE)cuttingboardthatwascleanedproperlybetweeneachprocessedfish.Carewastakentoavoidcontaminatingfilettissueswithmaterialreleasedfrominadvertentpunctureofinternalorgans.Anydarkmuscletissueinthevicinityofthelaterallineshouldnotbeseparatedfromthelightmuscletissuethatconstitutestherestofthemuscletissuemass.

9. Afterfilletingandskinningthefish,wecutoffapiececlosetoeightouncestoonepoundinsize(225to450grams),weighedthissample,blotdried,wrappeditinaluminumfoil,tapedit,andplacedthesampleinsealedzip-lockbag.Thisbagwasthenstoredinacleancooleronice.Thesamplesbagswerepositionedinthecoolersothatmeltedice-waterwasunabletoinfiltratethebags.Thebagswerealsoclearlymarkedwithspeciesandcaptureinformation(fishspecies,totallength,weightofsample,


capturedate,capturelocation)withatagconsistentwiththeU.S.EPAprotocol(Figure2).Thistagwasinsertedintoeachsample’szip-lockbag.

10. Afteradayoffieldsampling,allzip-lockbagsoftissuesampleswerestoredinafreezer(at-20oCor-4oF).Formethylmercurytesting,CDFWstandardsstatedthatsamplescanbefrozenforuptosixmonthspriortolaboratorytesting(EPA2000).

11. Fielddatasheets–weusedtheU.S.EPAfieldformwithonemodification:numberingthefishindividually(suchas,Lingcod#01)andignorethe“compositesample”sectionofthedatasheet.Also,weightofthewholefishandtissuesampleweightwasentered.Datasheetswereprintedonwater-proofpaperforfielduse.Aftereachfieldday,thedatasheetswerescannedandsavedasPDF’s.

12. FieldEquipmentlist–theHumboldtBayprojectusedalistconsistentwiththeU.S.EPArecommendationsforcollectionoftissuesamplesinthefield(AppendixA).

Figure1.Exampleofmeasurementoftotallength(fromU.S.EPA2000).


Figure2.ExampleofU.S.EPAsampleIDlabelandlabelinstructions(fromU.S.EPA2000).

Forthemostpart,skinlessfiletsoffishweretested,consistentwiththefleshnormallyconsumedbytheHumboldtBayanglingcommunity.TheU.S.EPA(2000)statesthat,“usingskinlessfilletsforassessingmercuryexposuresformembersofthegeneralpopulationandmost

recreationalfishersismostconservative.Becausemercuryisdifferentiallyconcentratedin

muscletissue,leavingtheskinonthefishfilletactuallyresultsinalowermercuryconcentration

pergramofskin-onfilletthanpergramofskin-offfillet.Inaddition,fewconsumersinthe

generalpopulationeattheskinofthefish,whichjustifiesitsremovalforanalysis,particularly

whenmonitoringconcernsaredirectedsolelyatmercurycontamination.”However,theexceptionwastestingskin-onmeatofWalleyeSurfperchandJacksmeltduetotheirrelativelysmallsizeandthefactthatthesefishareusuallypreparedwithskin-on.Thetissuesamplesizeofafiletfromeachcapturedfishwasbetweeneightouncesandonepoundandwasweighedwithadigitaltrayscale.Again,theexceptionsweretheWalleyeSurfperchandJacksmeltbecauseoftheirsmallsize–eachsamplefromthesefishconsistedofaheadedandgutted


carcass,similartohowthesespecieswouldbecleanedpriortocooking.Theseheadedandguttedcarcasseswereweighedtothe0.1poundsonadigitaltrayscale.

Methods-TissueSampleTestingandReporting:

TissuesamplesweresenttoCEBAMAnalytical,Inc.,locatedinBothell,Washington.CEBAMAnalyticalwasfoundedin1995byDr.LianLiangandspecializesintheanalysisandspeciationofmercuryinvarioussamplesusingmodifiedEPA1630andEPA1631Methods.TheHumboldtBaytissuesampleswereanalyzedforbothmethylmercuryandtotalmercury.Ofthetotalamountofmercuryfoundinfishmuscletissue,methylmercuryoftencomprisesmorethan95percentandisalsothemoretoxicform(Bloom,1992).Severalstudieshavegenerallyshownthatasfishage,mercuryconcentrationsintheirfleshincrease,includingconcentrationsofmethylmercury(U.S.EPA2000).Becauseofthesereasons,totalmercuryisusuallyanalyzedformostfishstudiesandassumedtobe100percentmethylmercuryforthepurposesofconservativeriskassessment(Smithetal.2016;Davisetal.2012).ThefishsampledfromHumboldtBayhadmethylmercuryvaluesthatwere81%to96%ofthetotalmercury.Ourresultsarereportedaslevelsoftotalmercuryinpartspermillion(ppm),consistentwithotherrecentassessmentscompletedinCaliforniacoastalwatersbytheSurfaceWaterAmbientMonitoringProgram(Davisetal.2012)andtheOfficeofEnvironmentalHealthHazardAssessment(Smithetal.2016).

ThetotalmercurythresholdsusedfortheHumboldtBaystudywereconsistentwithAdvisoryTissueLevels(ATLs)developedbyOEHHAandSWAMP(KlasingandBrodberg2008;Davisetal.2012;Smithetal.2016).TheOEHHAfishadvisoryprocessconsidersboththehealthbenefitsoffishconsumptionandtheriskfromexposuretothechemicalcontaminantsfoundinfish.Benefitsareincludedintheadvisoryprocessbecausethereisconsiderableevidenceandscientificconsensusthatfishshouldbepartofahealthy,well-balanceddiet.Thus,theATLsconsiderboththetoxicityofthechemicalandthepotentialhealthbenefitsofeatingfish.OEHHAusestheATLstodeterminethemaximumnumberofservingsperweekthatconsumerscaneat,foreachspeciesandateachlocation,tolimittheirexposuretothesecontaminants.TheOEHHAestablishedthreeATLthresholdsbasedageandsexbecausefetusesandchildrenaremoresensitivetothetoxiceffectsofmethylmercury.TheATLsforthesensitivepopulation,includingwomenwhomightbecomepregnant(typically18to45yearsofage)andchildrenarelowerthanforwomenover45yearsoldandmen.ThelowerATLvaluesforthesensitivepopulationprovideadditionalprotectiontoallowfornormalgrowthanddevelopmentofthebrainandnervoussystemofunbornbabiesandchildren(Smithetal.2016).

The“donotconsume”mercuryATLforchildrenandwomenuptoage45is0.44ppmandforwomenoverage45andmenis1.31ppm.The“consumenomorethanoneservingperweek”ATLforchildrenandwomenuptoage45isbetween0.15and0.44ppm.Foranadult,one


servingisconsideredaneight-ounceuncookedskinlessfilet(fourouncescooked).Aservingforachildishalfthat(fourouncesuncookedandtwoouncescooked).OEHHA’sthirdATLformercuryis0.07ppmwasalowerboundthresholduntiltheATLtablewasupdatedinNovember2017.ThenewtableaddedATLsforfour,five,six,andsevenservingsperweek(KlasingandBrodberg2008).

Results–MercuryLevelsofFishTestedfromHumboldtBay

InAugustof2016,HumboldtBaykeeperenlistedtheservicesofCaptainPhilGlennandhisboattheBluefintoassistincollectingfishforthestudy.Ontwohalf-daytripswecaughtfivelegal-sizedCaliforniaHalibut,threeBatRaysandoneLeopardShark.NumerousundersizedhalibutandBrownSmooth-houndSharkswerecaughtandreleased.AdditionalsamplinginSeptemberof2016conductedbyRossTaylorandAssociates(RTA)resultedinsamplesfromtwomoreBatRaysandaLingcod.ClamsampleswerecollectedinSouthHumboldtBaywiththeassistanceoftheWiyotTribeonMarch30,2017.AdditionalsamplingbyRTAoccurredonJuly3rd,21stand27thandonSeptember24thand29thof2017.Duringthesefivesamplingeffortsthefollowingsampleswereobtained:fourLingcod,twoBlackRockfish,fiveWalleyeSurfperch,twoJacksmelt,andoneCaliforniaHalibut.FarmedoysterswereharvestedinNorthHumboldtBaybyCoastSeafoodsCompanyinEureka.

ThesixCaliforniaHalibuttestedrangedinsizefrom4.8poundsto36poundsintotalweight(Table1andFigure3).FiveofthesefishwerecaughtnorthoftheSamoaBridge,andthesixthfishwascapturedsouthoftheSamoaBridgeneartheCoastGuardStation(Table1andFigure3).Thesesixfish(includingduplicatetests)hadtotalmercurylevelsbetween0.094and0.354ppm,andanaverageof0.204ppm(Table1andFigure3).Mostofthesevaluesarewithinthe“nomorethanoneservingperweek”ATLrangeforchildrenandwomenundertheageof45.

FiveBatRaysweretestedandthesefishrangedinsizebetween7.6poundsand48poundsintotalweight(Table1andFigure3).AllfiveBatRayswerecaughtnorthoftheSamoaBridge.Thesefivefish(includingduplicatetests)hadtotalmercurylevelsbetween0.121and0.423ppm,andanaverageof0.276ppm(Table1andFigure3).Mostofthesevaluesarewithinthe“nomorethanoneservingperweek”ATLrangeforchildrenandwomenundertheageof45.

FiveLingcodwerecaughtwhilefishingalongthenorthandsouthjettiesattheentrancetoHumboldtBay.Thesefishrangedinsizebetween3.6poundsand9.2poundsintotalweight(Table1andFigure3).Thesefivefish(includingduplicatetests)hadtotalmercurylevelsbetween0.1459and0.5405ppm,andanaverageof0.3157ppm(Table1andFigure3).Fourofthesevaluesarewithinthe“nomorethanoneservingperweek”ATLrangeforchildrenandwomenundertheageof45andthefishthatweighed9.2poundsexceededtheATLof0.44ppm(donotconsumeforchildrenandwomenuptoage45).ThefiveLingcodcaughtalongthe


HumboldtBayjettieshadconsistentincreasesoftotalmercurywithincreasedbodyweight(Table1andFigure3).HumboldtBaykeepertestedthetotalmercurylevelsoffourLingcodcaughtin2005intheoceannearCapeMendocino.Thesefishrangedinsizefrom6.2poundsto25.4poundsintotalweightandhadtotalmercuryvaluesbetween0.362and0.910ppm(Table1andFigure3).ThethreelargestfishwereabovetheATLof0.44ppm,thedonotconsumelevelforchildrenandwomenuptoage45.

FiveWalleyeSurfperchwerecaughtfromtheHumboldtBayRedwoodTerminalDock,locatedonthewestsideofthebay,southoftheSamoaBridge.Thesefivefishrangedinsizebetween2.2ouncesand2.8ounces,withrelativelylowtotalmercuryvaluesof0.1004to0.1360ppm(Table1andFigure3).

TwoBlackRockfishwerecaughtalongthesouthjettyattheentrancetoHumboldtBay.Thesetwofishweighed2.4and2.1pounds,withrelativelylowtotalmercuryvaluesbetween0.1320and0.1340ppm(Table1andFigure3).

OneLeopardSharkwascaughtinthenorthsectionofHumboldtBayinthechannelthatheadsnorthtowardsArcata.Thisfishhadatotalweightof20.4poundsandatotalmercurylevelof1.292ppm(Table1andFigure3).ThisLeopardSharkhadthehighestleveloftotalmercuryofthe34samplestestedfromfishcaughtwithinHumboldtBay(Table1andFigure3).OtherrecentstudiesthattestedLeopardSharkscaughtinCaliforniaallresultedinhighlevelsoftotalmercury(Smithetal.2016;Davisetal.2010).

WealsoincludedthetotalmercurylevelsoffiveChinookSalmontestedbyBaykeeperin2005becausetheimportanceoftheoceansalmonfisherytoNorthcoastanglers.Thesefivesalmonrangedinsizefrom4.7poundsto8.5poundsandallhadrelativelylowtotalmercuryvaluesbetween0.027and0.051ppm(Table1andFigure3).

TheaveragemercuryconcentrationintheAlbacorecaughtoffHumboldtCountycoastwas0.110ppm.TheseresultsareconsistentwithastudyofalbacorecaughtinOregonin2003,whichfoundaveragemercuryconcentrationsof0.14ppm(Morrisseyetal.2008).

TheshellfishtestedformercuryincludedHorseneck,Littleneck,andMarthaWashingtonclamsandoystersculturedinHumboldtBay.Alltheshellfishsamplestestedwerebelow0.07ppmandconsidered“safetoeat”inregardstototalmercury(Figure4).


Table1.HumboldtBaymercurytestingresultsforeightfishspecies.

CollectionDate

Species Lab’sTissueSampleID#

TotalLength(inches)

WholeWeight(pounds)

TotalMercury(ppm)

SampleLocationandDescription

8/24/2016 CaliforniaHalibut CAHAL-001 24.0 5.4 0.130 NorthofSamoaBridgeinwestchannel8/24/2016 CaliforniaHalibut CAHAL-001-D 24.0 5.4 0.138 NorthofSamoaBridgeinwestchannel8/24/2016 CaliforniaHalibut CAHAL-002 23.6 5.4 0.094 NorthofSamoaBridgeinwestchannel8/24/2016 CaliforniaHalibut CAHAL-003 22.8 4.8 0.206 NorthofSamoaBridgeinwestchannel8/24/2016 CaliforniaHalibut CAHAL-004 22.8 5.1 0.152 NorthofSamoaBridgeinwestchannel8/24/2016 CaliforniaHalibut CAHAL-005 24.8 5.7 0.354 NorthofSamoaBridgeinwestchannel8/24/2016 CaliforniaHalibut CAHAL-005-D 24.8 5.7 0.342 NorthofSamoaBridgeinwestchannel9/24/2017 CaliforniaHalibut CAHAL-006 45.5 36.0 0.220 NearCoastGuardStation8/20/2016 BatRay BATRY-001 28.3 48.0 0.396 NorthofSamoaBridgeinwestchannel8/20/2016 BatRay BATRY-002 15.0 7.6 0.160 NorthofSamoaBridgeinwestchannel8/24/2016 BatRay BATRY-003 23.2 24.4 0.383 NorthofSamoaBridgeinwestchannel8/24/2016 BatRay BATRY-003-D 23.2 24.4 0.423 NorthofSamoaBridgeinwestchannel8/26/2016 BatRay BATRY-004 19.3 15.2 0.322 NorthofSamoaBridgeinwestchannel8/26/2016 BatRay BATRY-005 20.1 15.8 0.121 NorthofSamoaBridgeinArcatachannel8/26/2016 BatRay BATRY-005-D 20.1 15.8 0.128 NorthofSamoaBridgeinArcatachannel10/20/2016 Lingcod#1 LCOD-001 22.5 3.6 0.1459 Southjetty10/20/2016 Lingcod#1duplicate LCOD-001-D 22.5 3.6 0.1461 Southjetty7/21/2017 Lingcod#2 LCOD-002 29.1 9.2 0.5405 Northjetty7/21/2017 Lingcod#3 LCOD-003 26.0 6.8 0.4055 Northjetty7/21/2017 Lingcod#3duplicate LCOD-003-D 26.0 6.8 0.4198 Northjetty7/29/2017 Lingcod#4 LCOD-004 25.3 4.9 0.2681 Southjetty9/27/2017 Lingcod#5 LCOD-005 26.4 6.5 0.2839 Southjetty


Table1(continued).HumboldtBaymercurytestingresultsforeightfishspecies.

CollectionDate

Species Lab’sTissueSampleID#

TotalLength(inches)

WholeWeight(pounds)

TotalMercury(ppm)

SampleLocationandDescription

2005 Lingcod LCOD-1-2005 N/A 25.4 0.910 OceannearCapeMendocino2005 Lingcod LCOD-2-2005 N/A 20.2 0.853 OceannearCapeMendocino2005 Lingcod LCOD-3-2005 N/A 10.6 0.599 OceannearCapeMendocino2005 Lingcod LCOD-4-2005 N/A 6.2 0.326 OceannearCapeMendocino

7/03/2017 WalleyeSurfperch#1 SHSPR-001 6.9 2.6oz. 0.1171 RedwoodTerminalDock7/03/2017 WalleyeSurfperch#2 SHSPR-002 6.5 2.8oz. 0.1105 RedwoodTerminalDock7/03/2017 WalleyeSurfperch#3 SHSPR-003 5.9 2.2oz. 0.1125 RedwoodTerminalDock7/03/2017 WalleyeSurfperch#4 SHSPR-004 6.4 2.3oz. 0.1004 RedwoodTerminalDock7/03/2017 WalleyeSurfperch#5 SHSPR-005 6.1 2.4oz. 0.1360 RedwoodTerminalDock7/29/2017 BlackRockfish#1 BLRCO-001 14.9 2.4 0.134 Southjetty9/27/2017 BlackRockfish#2 BLRCO-002 13.3 2.1 0.132 Southjetty9/27/2017 BlackRF#2duplicate BLRCO-002-D 13.3 2.1 0.133 Southjetty7/03/2017 Jacksmelt#1 JSMEL-001 10.6 4.6oz. 0.0762 RedwoodTerminalDock7/03/2017 Jacksmelt#2 JSMEL-002 11.0 6.2oz. 0.0821 RedwoodTerminalDock8/24/2016 LeopardShark#1 LEOSH-001 52.0 20.4 1.292 NorthofSamoaBridgeinArcatachannel

2005 ChinookSalmon CS-1-2005 N/A 4.7 0.046 Ocean-westofHumboldtBayentrance2005 ChinookSalmon CS-2-2005 N/A 5.0 0.051 Ocean-westofHumboldtBayentrance2005 ChinookSalmon CS-3-2005 N/A 6.7 0.045 Ocean-westofHumboldtBayentrance2005 ChinookSalmon CS-4-2005 N/A 8.5 0.027 Ocean-westofHumboldtBayentrance2005 ChinookSalmon CS-5-2005 N/A 6.8 0.048 Ocean-westofHumboldtBayentrance


Figure3.HumboldtBaymercurytestingresultsforeightfishspecies.


Figure4.HumboldtBaymercurytestingresultsforfourshellfishspecies.


Results–AngerSurveys:

Atotalof80shore-basedanglerswereinterviewedtofindoutwhichfishspeciespeoplecatch

andeatmostfrequentlyfromHumboldtBay.ThesesurveysfocusedontheDelNorteStreet

PierandseveraldocksinEureka,theNorthJettyinSamoa,andtheMadRiverSloughBridgein

Manila.TheDelNorteStreetPieristheonlypublicfishingpierinHumboldtBay,andisavery

popularfishingspot(Figure5).Inaddition,anglersurveyswereconductedinSpanishatabilingualhealthfairinFortunaandatEnglish-as-a-Second-Language(ESL)classesinEureka.

AnglersurveyswerealsopostedonlineinbothSpanishandEnglish.

Figure5.TheDelNorteStreetPierinEurekaistheonlypublicfishingpierinHumboldtBay,and

wasthesiteofthemajorityofanglersurveysconductedforthisstudy.TheCityofEureka

estimatesthat10to15anglersusetheDelNorteStreetpieraday.


Mostpeopleeatwhattheycatchorfeedittotheirfamilies,althoughsomearefishingforbait

tofishinoceanwaters.Ofthe80anglerssurveyed,fivesaidtheyeatleopardsharkfrom

HumboldtBay.Themajority(62)saidtheyeatshellfishfromthebay;ofthose,55eat

Dungenesscrabandrockcrab,41eatoysters,24eatclams,and19eatmussels.Whenasked,

“HowmanytimesdidyoueatfishfromHumboldtBayinthelast30days?”theanswersranged

from0to13.ThenumberofyearsanglerssurveyedhadbeenfishinginHumboldtBayranged

from“thisismyfirsttime”to“mywholelife”(Figure6).

Thecookingmethodspeopleusedincludeddeepfry,panfry,bake,grill,andboil.Ofthe63

respondentswhosaidtheycookfishtheycatchinoil,onlyfoursaidtheyreusedtheoil.Only

eightrespondentssaidtheyfreeze,can,orsmokefishtobeeatenthroughouttheyear.The

majority(57)removedtheskin,whilesevendidnot.AfishermanfromShelterCovewhowas

interviewedsaidhehadelevatedbloodlevelsofmercuryfromconsumingfresh,frozen,and

cannedfreshrockfish3-4timesaweek.Hisdoctoradvisedeliminatingallfishfromhisdietfor

threemonths,afterwhichhisbloodlevelsofmercurydeclined.

Figure6.ThenumberofyearsthatrespondentstotheanglersurveyshavefishedonHumboldt

Bay.


Recommendations–ConsumptionGuidelines:

TheultimatepurposeofthisstudyistoprovidethepublicwhofishinornearHumboldtBay

informationaboutmercurylevelsinthefishtheyandtheirfamiliesconsume.Theguidelines

providedarebasedonOEHHA’srecommendednumberofservingsperweekforthetwo

previouslymentionedpopulations:(1)womenundertheageof45andchildren,and(2)women

olderthan45andmenolderthan18yearsofage(Table2).Ocean-caughtChinookSalmonhad

thelowestmercurylevelsofthelocallytestedfishandaresafetoconsumeatasubsistence

levelof20to28mealspermonthbyallpeople(Table2).BecauseofthelowerATL’ssetfor

womenundertheageof45andchildren,allotherfishspeciesshouldbeconsumedatlower

frequencies,andinthecaseoflargerLingcodandallLeopardShark,avoidedalltogether(Table

2).

Table2.Averagemercurylevelsinpartspermillion(ppm)forfishspeciescaughtinornearHumboldtBayandguidelinesforconsumption.

Species AverageMercury

Levels,ppm

RecommendedServings*perWeek,

Women<45&Children1


Women>45&Men1

Oysters 0.026 7 7

Chinooksalmon 0.043 5 7

Clams 0.045 5 7

JackSmelt 0.079 2 7

LocalAlbacore 0.110 2 5

WalleyeSurfperch 0.115 2 5

BlackRockfish 0.131 2 4

CaliforniaHalibut 0.192 1 3

BatRay 0.281 1 2

Lingcod<10lbs. 0.330 1 2

Lingcod>10lbs. 0.787 AVOID 1

LeopardShark 1.476 AVOID AVOID*Servingsizes:adults=8ouncesuncooked(4ouncescooked);children=4ouncesuncooked(2ouncescooked).1OfficeofEnvironmentalHealthHazardAssessment’sNov.2017AdvisoryTissueLevelshttps://oehha.ca.gov/media/downloads/fish/report/atlmhgandothers2008c.pdf


Recommendations–FurtherTesting:

Basedonthestrongpublicinterestreceivedafterwereleasedourresultsviaradiointerview,

localnewsprint,tablingatseveralcommunityfunctions,socialmedia,andinputsolicitedfrom

tribalmembersandsportfishermen,thereappearstobeaneedforfurthertestingoffish

consumedbyHumboldtBaysportfishersandWiyotTribemembers.Aliteraturereviewof

mercurystudiesconductedthroughoutthePacificNorthwestrevealedawiderangeofmercury

levelsforfishandshellfishalsopresentinornearHumboldtBay(Careyetal.2014;Davisetal.

2012;Dykstra2008;SWRCB1998)(Table3).

Inquiriesaboutthemercurylevelsinlocally-caughtPacificHalibuthavebeenmadeby

HumboldtBay-basedsportfishers.Otherrequestshaveincludedtestingoflocallycaught

Cabezon,ChinaRockfish,GopherRockfish,andCopperRockfish.PacificLampreyisaspecies

harvestedatthemouthoftheEelRiverbyWiyotTribemembers,andthereisinterestintesting

lampreyformercury.Finally,wewereonlyabletoobtainasinglelegal-sizedLeopardShark

fromHumboldtBayandwouldliketotestseveraladditionalfishtohaveabetterunderstanding

oftherangeofmercuryvaluesinthisspecies.

Table3.Averagemercurylevelsinpartspermillion(ppm)forfishspeciestestedthroughoutthePacificNorthwest,alongwithOEHHA’srecommendedconsumptionlevels(KlasingandBrodberg,2008).

Species AverageMercury

Levels,ppm


Women<45&Children1


Women>45&Men1

Sardines 0.013 7 7

Anchovies 0.017 7 7

Mussels 0.041 5 7

DungenessCrab 0.074 2 7

PacificHalibut<40lbs. 0.202 1 3

PacificHalibut>40lbs. 0.606 AVOID 1

Cabezon 0.474 AVOID 1

ChinaRockfish 0.643 AVOID 1

GopherRockfish 0.760 AVOID 1

CopperRockfish 0.835 AVOID 1*Servingsizes:adults=8ouncesuncooked(4ouncescooked);children=4ouncesuncooked(2ouncescooked)


LiteratureCited:

ATSDR.1999.ToxicologicalProfileforMercury.AgencyforToxicSubstancesandDisease

Registry.CentersforDiseaseControl,U.S.DepartmentofHealthandHumanServices,Atlanta,GA.

Bloom,N.S.1992.Onthechemicalformofmercuryinediblefishandmarineinvertebrate

tissue.CanadianJournalofFisheriesandAquaticSciences49(5):1010-1017.Bose-O’Reilly,S.,K.M.McCarty,N.Steckling,andB.Lettmeier.2010.MercuryExposureand

Children’sHealth.CurrentProblemsinPediatricandAdolescentHealthCare40(8):186–215.

Carey,A.J.,L.A.Niewolny,J.A.LanksburyandJ.E.West.2014.ToxicContaminantsinDungenesscrab(Metacarcinusmagister)andSpotPrawn(Pandalusplatyceros)fromPugetSound,Washington,USA.WashingtonDepartmentofFishandWildlife.

Davis,J.A.,J.R.M.Ross,S.N.Bezalel,J.A.Hunt,A.R.Melwani,R.M.Allen,G.Ichikawa,A.

Bonnema,W.A.Heim,D.Crane,S.Swenson,C.Lamerdin,M.Stephenson,andK.Schiff.2012.ContaminantsinFishfromtheCaliforniaCoast,2009-2010:SummaryReportonaTwo-YearScreeningSurvey.AReportoftheSurfaceWaterAmbientMonitoringProgram(SWAMP).CaliforniaStateWaterResourcesControlBoard,Sacramento,CA.

Evenson,F.2006.MercuryIsn’tRisingInNorthCoastCommercialFish.CurrentsMagazine,

Spring2006.HumboldtBaykeeper,Eureka,CA.Gassel,M.andR.Broberg.2005.GeneralProtocolforSportFishingSamplingandAnalysis.

CaliforniaOfficeofEnvironmentalHealthHazardAssessment.CaliforniaEnvironmentalProtectionAgency,Sacramento,CA.

Klasing,S.andR.Brodberg.2008(UpdatedATLTableNovember2017).DevelopmentofFish

ContaminantGoalsandAdvisoryTissueLevelsforCommonContaminantsinCaliforniaSportFish:Chlordane,DDTs,Dieldrin,Methylmercury,PCBs,Selenium,andToxaphene.CaliforniaOfficeofEnvironmentalHealthHazardAssessment.CaliforniaEnvironmentalProtectionAgency,Sacramento,CA.

NCRWQCB.2012.FinalCalifornia2012IntegratedReport(303(d)List/305(b)Report)

SupportingInformation,RegionalBoard1-NorthCoastRegion.https://www.waterboards.ca.gov/water_issues/programs/tmdl/2012state_ir_reports/00001.shtml.


Silbernagel,S.M.,D.O.Carpenter,S.G.Gilbert,M.Gochfeld,E.GrothIII,J.M.Hightower,andF.M.Schiavone.2011.RecognizingandPreventingOverexposuretoMethylmercuryfromFishandSeafoodConsumption:InformationforPhysicians.JournalofToxicology2011:1-7.

Smith,W.,H.T.Pham,S.Klasing,M.Gassel,andS.Murphy.2016.Statewideadvisoryforeating

fishfromCaliforniacoastallocationswithoutsite-specificadvice.OfficeofEnvironmentalHealthHazardAssessment,Oakland,CA.59p.

TurtleIslandRestorationNetworkMercuryCalculator:

http://seaturtles.org/programs/mercury/U.S.EPA.2000.Guidanceforassessingchemicalcontaminantdataforuseinfishadvisories.

Volume1:Fishsamplingandanalysis,3rdedition.Report#EPA823-B-00-007.Verbrugge,L.A.2007.FishConsumptionAdviceforAlaskans:ARiskManagementStrategyto

OptimizethePublic’sHealth.AlaskaScientificAdvisoryCommitteeforFish,AlaskaDepartmentofPublicHealth.

Weiss-Penzias,P.S.,C.OrtizJr.,R.P.Acosta,W.Heim,J.P.Ryan,D.Fernandez,J.L.CollettJr.,

andA.R.Flegal.2012.TotalandmonomethylmercuryinfogwaterfromthecentralCaliforniacoast.GeophysicalResearchLetters39:3804-3809.


AppendixA.Recommendedequipmentlistforcollectingtissuesamplesinthefieldfor

methylmercurytesting.Developedforboat-basedsamplinginHumboldtBay,California.

1. FieldLogbook.2. Datasheets.3. SampleIDlabels.4. Clipboard.5. HandheldGPSunit(orboat-basedunit).6. Depthfinderonboattomeasuredepth(s)atcollectionlocation(s).7. Indeliblepens.8. Collectionequipment–rods,reels,bait,lures,landingnet,club,etc.9. Digitalcamerafortakingspecimenphotos.10. Measuringdevice–tapeorboard.11. Scaleforweighingfish.12. Scaleforweighingtissuesamples.13. Filetknivesandsharpeningstone.14. Aluminumfoil–extra-heavyduty.15. Freezertape.16. Gallonzip-lockbagsfortissuesamples.17. Foldingtableforprocessingfishandsamples.18. Plasticsheetortarptocoverfoldingtable.19. Cleaningboard.20. Coolerwithicefortemporarystorageoftissuesamples.21. Liquiddishsoap-forcleaninghands,knivesandotherprocessingequipmentbetween

samples.22. Distilledwaterforrinsinghands,knivesandotherprocessingequipmentbetween

samples.Severalgallons(atleast).23. Papertowels(twoorthreerolls).


APPENDIXB:PHOTOGRAPHSOFSAMPLEDFISHFROMHUMBOLDTBAY


FigureB-1.BatRay#1(weight=48.0pounds)caughtonAugust20,2016.

FigureB-2.BatRay#2(weight=24.4pounds)caughtonAugust28,2016.


FigureB-3.BlackRockfish#1caughtonJuly29,2017alongthesouthjettyofHumboldtBay.

FigureB-4.BlackRockfish#2caughtonSeptember27,2017alongthesouthjettyofHumboldtBay.


FigureB-5.Lingcod#2(weight=9.8pounds)caughtonJuly21,2017alongthenorthjettyofHumboldtBay.

FigureB-6.Lingcod#3(weight=6.8pounds)caughtonJuly21,2017alongthenorthjettyofHumboldtBay.


FigureB-7.WalleyeSurfperchcaughtonJuly3,2017.

FigureB-8.WalleyeSurfperch#1-5caughtonJuly3,2017.


FigureB-9.LeopardShark#1(weight=20.4pounds)caughtonAugust20,2016.

FigureB-10.CaliforniaHalibut#3(weight=5.1pounds)caughtonAugust24,2016.

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Mercury Testing of Sport/Food Fishes within Humboldt Bay · 2018-05-21 · Mercury Testing of Sport/Food Fishes within Humboldt Bay Project Purpose and Need Mercury advisories have