(PPT) The Green-Eyed Survivor Dogfish Shark Life History & Populations in the Gulf of Alaska - DOKUMEN.TIPS (2023)

The Green-Eyed Survivor Dogfish Shark Life History & Populations in the Gulf of Alaska. Cindy A Tribuzio School of Fish and Ocean Sciences University of Alaska Fairbanks Juneau Center. In Cooperation With……. Alaska Department of Fish and Game. NMFS AFSC Auke Bay Lab. Outline. - PowerPoint PPT Presentation

  • The Green-Eyed Survivor Dogfish Shark Life History &Populations in the Gulf of AlaskaCindy A TribuzioSchool of Fish andOcean SciencesUniversity of Alaska FairbanksJuneau Center

  • In Cooperation WithAlaska Department of Fish and Game

    NMFS AFSC Auke Bay Lab

  • OutlineSharks in AlaskaDogfish Biology and Fishery InfoProjectObjectivesData CollectionObjective Results and ConclusionsCurrentand Future Research

  • Gulf of Alaska Sharks8 shark species, 6 families12+ skatespecies, 2 families1 chimera, ratfish Hydrolagus colliei

  • Gulf of Alaska SharksBlue Shark, Prionace glauca

  • Gulf of Alaska SharksFamily LamnidaeMackerel sharksGreat WhiteSharkCarcharodon carchariasSalmon SharkLamna ditropis

  • Gulf of Alaska SharksBasking Shark, Cetorhinus maximus

  • Gulf of Alaska SharksSleeper Shark, Somniosus pacificus

  • Gulf of Alaska SharksBrown Cat Shark, Aprisurus brunneusCookieCutter

  • Gulf of Alaska SharksRaja familyBig SkateRaja binoculataLongnoseSkateRaja rhina

  • Gulf of Alaska SharksBathyraja family

  • Spiny Dogfish, Squalus acanthias

  • Geographic Distribution

    Worldwide distribution in temperate coastal areas

  • Dogfish Biology

    Worldwide distribution in temperate coastal areasSmall size (upto 1.3m long) and long lived (100 years)

    Stigma of being a Nuisance SpeciesEcologically important as bothpredator and prey

  • Common PerceptionsConsidered a nuisance speciesNationalFisherman, Nov 2004:

    Dogfish are wolves of the sea

    Blames dogfish for the decline in more desirable species such assea bass, porgies and baby codfish


  • Cultural Importance

  • Qqaaxhadajaat, the Dogfish WomanA woman went traveling with herhusband. She used to make fun of the dogfish. They went to visit asmall rock in the sea. When they were out there, the dogfish, whosehome the rock was, came and took the woman down into the sea. Thereshe discovered that the dogfish were really people. They had takenoff their dogfish blankets. After she had stayed in the house forsome time, fins began to grow upon her arms, her legs and her back.Her husband was searching for her everywhere, but he was not ableto find her. After a number of years he found her. Her face hadremained unchanged; but fins had grown on her arms, on her legs, onher back, and on her head. She never returned. Ever since that timeher family have used the dogfish crest, and their house is calledDogfish House.

  • Size and Age of Spiny DogfishHeight: 44 in, 112 cmHeight: 39in,99 cm

  • Size and Age of Spiny DogfishMitch, Age 5Height: 44 in, 112cmClint, Age 3Height: 39 in,99 cm

    Spiny Dogfish, Age 5Length: 13 in, 35 cmSpiny Dogfish, Age3Length: 11 in, 28 cm

  • Size and Age of Spiny DogfishMitch, Age 5Height: 44 in, 112cmClint, Age 3Height: 39 in,99 cm

    Spiny Dogfish, Age >100 years!!!Length: 44 in, 112 cmSpinyDogfish, Age 48 years!!!Length: 39 in, 99 cm

  • Reproductive BiologyFemales mature at ~35 yrs~22 monthgestation, 7-12 pups averageFecundity and offspring survivalincrease as female ages/grows larger

  • Commercial Shark Fishing

  • North Atlantic ExperienceThe situation:Fishery developed rapidly(1988), was stable for a short period then declined

    40 years of fishery independent survey data

    Commercial fishery targeted large individuals, landings weredominated by mature females

  • North Atlantic ExperienceThe problems1988-2000: average size oflanded female dogfish dropped from 4 kg to 2 kg and 95 to 79cmAlmost no recruitment after 10 years of fishingpressure1989-2003: fishery removed nearly 213 K mt of spinydogfish, biomass of spawning females dropped by 75%, total biomassof the population dropped by about 30%

  • North Atlantic ExperienceThe resultsFew large females availableto reproduce, small females producing pups with lower survival

  • North Atlantic ExperienceThe resultsFew large females availableto reproduce, small females producing pups with lowersurvivalReduction in the number of juveniles recruiting tomaturity

  • North Atlantic ExperienceThe resultsFew large females availableto reproduce, small females producing pups with lowersurvivalReduction in the number of juveniles recruiting tomaturityNMFS declared over fished in 1998

  • North Atlantic ExperienceThe resultsFew large females availableto reproduce, small females producing pups with lowersurvivalReduction in the number of juveniles recruiting tomaturityNMFS declared overfished in 1998Atlantic States MarineFisheries Commission adopted catch limits of a 4 million poundbycatch cap quota and 300/600 pound trip limits for the 2005-2006fishing season

  • North Pacific Ocean FisheryCommercially fished for over 100years

    University of Washington Digital ImageCollectionwww.sharkinfo.com

  • North Pacific Ocean FisheryBritish Columbia and Washington Statemanage transboundary fishery independentlyWashington State fisheryis larger (tonnage) than BC fisheryStock assessments in WA showdecreasing abundances, reflected in catch. Opposite in BC.

  • North Pacific Ocean FisheryFishery Characteristics:Targetslarger females for size and ovariesMost products exportedinternationallyValuable marine export (with increasing marketpotential)

    WA fishery generally targets inside (Puget Sound) dogfish, BCfishery targets outside (Coastal) dogfish

    Outside dogfish more migratory, where inside dogfish tend tostay within home region (Strait of Georgia or Puget Sound)

    Puget Sound and Strait of Georgia dogfish cannot be solddomestically for human consumption

  • Current Status of Alaskan FisheryFederal bycatch fishery inKodiakYakutat Bay: bycatch retention up to 35% of total catch inhook and line fisheries, retention up to 100% of total catch in setnet fisheriesCook Inlet: targeted fishery via Commissioners Permitbegan in April 2005

  • Fishery ConcernsShark fisheries are generally notsustainableLife history (late mature, low fecundity) does notsupport fishery

    Ecological impact of fisheryDogfish may have valuable role inecosystem

  • Urgency and Management IssuesRegular bycatch in commercialfisheriesLonglineTrawlSeasonal bycatch in commercialfisheriesSalmon fisheriesSport fish bycatch

  • Urgency and Management IssuesNo estimates of bycatch mortalityand its impacts on dogfish populationsIncreasing fishing pressurein federal waters where allowed as other speciesIncreased pressurein AK state waters for commercial fishery

  • Need for ResearchNo stock assessments of spiny dogfishLittleinformation on region specific biology and ecologyWhat levels ofharvest might be sustainable?Is a targeted fishery eveneconomically feasible?

  • Alaskan Dogfish ResearchProject funded by NPRB and NMFSFellowshipStudy began in July 2004 and planned though2007Cooperative with UAF, UW, NMFS, and ADF&G

    Goals:Estimate demographic parameters, stock assessment Developconceptual model of life historyDescribe food and feeding habits(food web model)Analyze age/size composition dataExplore historicalbycatch for trends in abundanceInvestigate inter-lab variation inaging techniques

  • Data CollectionSize, sex and maturityReproductive InfoStomachContentsAgeBlood

  • Measurments

  • Male Maturity

  • Female Maturity

  • Female Maturity

  • Reproductive InfoTiming of reproductive eventsEmbryo size anddevelopmentSex of embryos

  • Pregnancy

  • Pregnancy Timeline

  • Stomach ContentsGross ID in fieldContents stored in Formalin andreturned to lab for specific ID and sizes of food items

  • Age and Blood2nd Dorsal Spine for agingBlood for reproductivehormones

  • Survey MethodsSport FishingYakutat BayHomer/Cook InletLonglineCross SoundYakutat BayNMFS Sablefish SurveyOthersADF&G surveysin SE Alaska, Prince William Sound, Cook InletNMFS biennial trawlsurveyVarious commercial bycatch

  • Sample Locations

  • Sport FishingHalibut fishing techniquesHerring/Salmon BaitChum:dogfish scraps, herring, rockfish and salmon scraps ~16% of totalsamples

  • LonglineSablefish fishing gearSquid or Herring Bait~84% of totalsamples

  • Early Results

  • Sport vs. Longline

  • Pupping Season23 Pregnant females sampled223 total embryosGrowthrates from Ketchen, 1972

  • Pupping Season23 Pregnant females sampled223 total embryosGrowthrates from Ketchen, 1972

  • Fecundity

  • Stomach Contents

  • Stomach Contents

  • Gulf Bay

  • Future Sampling PlansNew sampling toys:2006:Cordova, CopperRiver Salmon bycatchHomer/Cook Inlet sport fishing and Ninilchikset net fisheryNMFS Sablefish surveyADF&G Kamishak Bay andPrince William Sound surveyYakutat Bay, aerial and trawl

  • Expected Project OutcomesDescribe seasonal size and agedistributions, reproductive patternsGain better understanding ofdogfish feeding ecology and food web dynamicsEstimate regionspecific stock assessment parameters Estimate GOA abundance fromparameters Build inter-agency cooperation

  • Other dogfish projectsTagging study Dean Courtney, NMFS

  • Other dogfish projectsStable Isotope/Feeding Ecology AlexAndrews, UAF

    Socioeconomics of a potential fisheryJason Gasper, UAF

    Creel census and bycatch sampling with ADF&G

  • Thanks!NPRBNMFS AFSCNMFS Auke Bay LabDean Courtney, ChrisLunsford, Brian VanWinkle, Dave Clausen, Mitch LorenzADF&GWillyDunne, Ken Goldman, Bob Johnson, Scott Meyer, Tory OConnell, ScottPegau, Charlie Stock, Charlie Trowbridge, Mike Vaughn, Gordie WoodsF/V Alaskan LeaderF/V Kingfisher-Chris and Natalie Ekstrom, KyleDickersonF/V Sea View-John EthridgeF/V Winter King-Rex Murphy,Holly VanPelt, MikeyF/V Ocean Prowler

    Top picture shows size measurements taken on all dogfish, PCL,FL, TLnat and TLextBottom Left is Clasper Inner Length measurementfor males onlyBottom Center is mature, fully calcified clasper withspine extendedBottom Left is immature, short and flexibleLeftGrouping:Left three pictures are mature female reproductive tracts,farthest left is female in earliest stages of pregnancy with largecandle containing multiple embryos in uterusLeft Center is femaleabout halfway through gestation with 5 free embryos inuterusLeft-Right is female in between pregnancies, with emptyuterus and large ovary with ova ready for ovulation.

    Right grouping:Immature female reproductive tracts. All havesmall ovaries, undeveloped shell glands and narrow uterus.Leftimage is stages of pregnancy as seen by embryo developmentRightimage is male embryo, shows that claspers can be identified earlyin gestation.Spines are cleaned and dried for aging.Serum isseparated from blood for assays of reproductive hormonesCrossSound, Yakutat and Cordova to Kodiak LL SurveyTop Right picture isherring bait perfectly bitten through by dogfishBottom Rightpicture is chum bucketSummary of all samples taken to date

    Comparisons of sport and longline catches26% of samples fromsport fishing, 74% from longlineIn sport fishing, 17% were malesand 83% femalesFrom longlining, 30% were males and 70% femalesFromsport fishing, 87% of males were mature and 23% of females werematureFrom longlining, 72% of males were mature and 20% of femaleswere matureTL of embryos was used to determine how far intogestation they were, using growth rates published in Ketchen,1972.This gestation age is used to estimate a date of parturition,assuming a 22 month gestation.From 9 pregnant females and a totalof 40 pups, the pupping season is estimated to occur in March andAprilTL of embryos was used to determine how far into gestationthey were, using growth rates published in Ketchen, 1972.Thisgestation age is used to estimate a date of parturition, assuming a22 month gestation.From 9 pregnant females and a total of 40 pups,the pupping season is estimated to occur in March and AprilNumberof food types increases greatly with number of stomachsexamined.

    This is only rough field ID, detailed analysis isforthcoming.

    Stomachs from open water tended to have more pelagic food types,while stomachs from bays or protected waters had more benthic foodtypes.

    Chum and bait are most common food items, even canabalismVideois NMFS intern Brian VanWinkle during May sampling trip to YakutatBay

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