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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.

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Presentation on theme: "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."— Presentation transcript:

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2 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

3 In Cooperation With…… Alaska Department of Fish and Game NMFS AFSC Auke Bay Lab

4 Outline  Sharks in Alaska  Dogfish Biology and Fishery Info  Project Objectives  Data Collection  Objective Results and Conclusions  Current and Future Research

5 Gulf of Alaska Sharks  8 shark species, 6 families  12+ skate species, 2 families  1 chimera, ratfish Hydrolagus colliei

6 Gulf of Alaska Sharks  Blue Shark, Prionace glauca

7 Gulf of Alaska Sharks  Family Lamnidae Mackerel sharks Great White Shark Carcharodon carcharias Salmon Shark Lamna ditropis

8 Gulf of Alaska Sharks  Basking Shark, Cetorhinus maximus

9 Gulf of Alaska Sharks  Sleeper Shark, Somniosus pacificus

10 Gulf of Alaska Sharks  Brown Cat Shark, Aprisurus brunneus  Cookie Cutter

11 Gulf of Alaska Sharks Raja family  Big Skate Raja binoculata  Longnose Skate Raja rhina

12 Gulf of Alaska Sharks Bathyraja family

13 Spiny Dogfish, Squalus acanthias

14 Geographic Distribution  Worldwide distribution in temperate coastal areas

15 Dogfish Biology  Worldwide distribution in temperate coastal areas  Small size (up to 1.3m long) and long lived (100 years)  Stigma of being a “Nuisance Species”  Ecologically important as both predator and prey

16 Common Perceptions Considered a nuisance species National Fisherman, Nov 2004:  “Dogfish are wolves of the sea”  Blames dogfish for the decline in more desirable species such as sea bass, porgies and “baby codfish”

17 Cultural Importance

18 Qqaaxhadajaat, the Dogfish Woman A woman went traveling with her husband. She used to make fun of the dogfish. They went to visit a small rock in the sea. When they were out there, the dogfish, whose home the rock was, came and took the woman down into the sea. There she discovered that the dogfish were really people. They had taken off their dogfish blankets. After she had stayed in the house for some time, fins began to grow upon her arms, her legs and her back. Her husband was searching for her everywhere, but he was not able to find her. After a number of years he found her. Her face had remained unchanged; but fins had grown on her arms, on her legs, on her back, and on her head. She never returned. Ever since that time her family have used the dogfish crest, and their house is called Dogfish House.

19 Mitch Age: 5 Clint Age: 3 Size and Age of Spiny Dogfish Height: 44 in, 112 cm Height: 39 in, 99 cm

20 Size and Age of Spiny Dogfish Mitch, Age 5 Height: 44 in, 112 cm Clint, Age 3 Height: 39 in, 99 cm Spiny Dogfish, Age 5 Length: 13 in, 35 cm Spiny Dogfish, Age 3 Length: 11 in, 28 cm

21 Size and Age of Spiny Dogfish Mitch, Age 5 Height: 44 in, 112 cm Clint, Age 3 Height: 39 in, 99 cm Spiny Dogfish, Age >100 years!!! Length: 44 in, 112 cm Spiny Dogfish, Age 48 years!!! Length: 39 in, 99 cm

22 Reproductive Biology  Females mature at ~35 yrs  ~22 month gestation, 7-12 pups average  Fecundity and offspring survival increase as female ages/grows larger Photo by Rustin Director

23 Commercial Shark Fishing

24 North Atlantic Experience  The 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 were dominated by mature females

25 North Atlantic Experience  The problems……  : average size of landed female dogfish dropped from 4 kg to 2 kg and 95 to 79 cm  Almost no recruitment after 10 years of fishing pressure  : fishery removed nearly 213 K mt of spiny dogfish, biomass of spawning females dropped by 75%, total biomass of the population dropped by about 30%

26 North Atlantic Experience  The results  Few large females available to reproduce, small females producing pups with lower survival

27 North Atlantic Experience  The results  Few large females available to reproduce, small females producing pups with lower survival  Reduction in the number of juveniles recruiting to maturity

28 North Atlantic Experience  The results  Few large females available to reproduce, small females producing pups with lower survival  Reduction in the number of juveniles recruiting to maturity  NMFS declared over fished in 1998

29 North Atlantic Experience  The results  Few large females available to reproduce, small females producing pups with lower survival  Reduction in the number of juveniles recruiting to maturity  NMFS declared overfished in 1998  Atlantic States Marine Fisheries Commission adopted catch limits of a 4 million pound bycatch cap quota and 300/600 pound trip limits for the fishing season

30 University of Washington Digital Image Collection North Pacific Ocean Fishery Commercially fished for over 100 years

31 North Pacific Ocean Fishery  British Columbia and Washington State manage transboundary fishery independently  Washington State fishery is larger (tonnage) than BC fishery  Stock assessments in WA show decreasing abundances, reflected in catch. Opposite in BC.

32 North Pacific Ocean Fishery  Fishery Characteristics:  Targets larger females for size and ovaries  Most products exported internationally  Valuable marine export (with increasing market potential)  WA fishery generally targets inside (Puget Sound) dogfish, BC fishery targets outside (Coastal) dogfish  Outside dogfish more migratory, where inside dogfish tend to stay within home region (Strait of Georgia or Puget Sound)  Puget Sound and Strait of Georgia dogfish cannot be sold domestically for human consumption

33 Current Status of Alaskan Fishery  Federal bycatch fishery in Kodiak  Yakutat Bay: bycatch retention up to 35% of total catch in hook and line fisheries, retention up to 100% of total catch in set net fisheries  Cook Inlet: targeted fishery via Commissioners Permit began in April 2005

34 Fishery Concerns  Shark fisheries are generally not sustainable  Life history (late mature, low fecundity) does not support fishery  Ecological impact of fishery  Dogfish may have valuable role in ecosystem

35  Regular bycatch in commercial fisheries  Longline  Trawl  Seasonal bycatch in commercial fisheries  Salmon fisheries  Sport fish bycatch Urgency and Management Issues

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38  No estimates of bycatch mortality and its impacts on dogfish populations  Increasing fishing pressure in federal waters where allowed as “other species”  Increased pressure in AK state waters for commercial fishery

39 Need for Research  No stock assessments of spiny dogfish  Little information on region specific biology and ecology  What levels of harvest might be sustainable?  Is a targeted fishery even economically feasible?

40 Alaskan Dogfish Research  Project funded by NPRB and NMFS Fellowship  Study began in July 2004 and planned though 2007  Cooperative with UAF, UW, NMFS, and ADF&G  Goals: 1) Estimate demographic parameters, stock assessment 2) Develop conceptual model of life history 3) Describe food and feeding habits (food web model) 4) Analyze age/size composition data 5) Explore historical bycatch for trends in abundance 6) Investigate inter-lab variation in aging techniques

41 Data Collection  Size, sex and maturity  Reproductive Info  Stomach Contents  Age  Blood

42 Measurments

43 Male Maturity

44 Female Maturity

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46 Reproductive Info  Timing of reproductive events  Embryo size and development  Sex of embryos

47 Pregnancy

48 Pregnancy Timeline

49 Stomach Contents  Gross ID in field  Contents stored in Formalin and returned to lab for specific ID and sizes of food items

50 Age and Blood  2 nd Dorsal Spine for aging  Blood for reproductive hormones

51 Survey Methods  Sport Fishing  Yakutat Bay  Homer/Cook Inlet  Longline  Cross Sound  Yakutat Bay  NMFS Sablefish Survey  Others  ADF&G surveys in SE Alaska, Prince William Sound, Cook Inlet  NMFS biennial trawl survey  Various commercial bycatch

52 Sample Locations

53 Sport Fishing  Halibut fishing techniques  Herring/Salmon Bait  Chum: dogfish scraps, herring, rockfish and salmon scraps  ~16% of total samples

54 Longline  Sablefish fishing gear  Squid or Herring Bait  ~84% of total samples

55 Early Results Year Sampling Location Start Date TypeMalesFemalesStomachsBloodSpines 2004 Yakutat Bay 7/27/2004Sport GOA Cordova- Kodiak 8/9/2004LL SE near Sitka 2/16/2005LL Cross Sound 4/21/2005LL Yakutat Bay 5/8/2005LL /24/2005Sport Cook Inlet 6/25/2005Sport Yakutat Bay 6/27/2005LL GOA Ketchikan- Cordova 7/9/2005LL Totals

56 Sport vs. Longline SportLongline Total # Samples 161, 16% 831, 84% Males in Sample 28, 17% 266, 32% Females in Sample 133, 83% 565, 68% Mature Males 13, 87% 124, 60% Mature Females 21, 23% 66, 24%

57 Pupping Season  23 Pregnant females sampled  223 total embryos  Growth rates from Ketchen, 1972

58 Pupping Season  23 Pregnant females sampled  223 total embryos  Growth rates from Ketchen, 1972

59 Fecundity

60 Stomach Contents

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62 Gulf Bay

63 Future Sampling Plans  2006:  Cordova, Copper River Salmon bycatch  Homer/Cook Inlet sport fishing and Ninilchik set net fishery  NMFS Sablefish survey  ADF&G Kamishak Bay and Prince William Sound survey  Yakutat Bay, aerial and trawl  New sampling toys:

64 Expected Project Outcomes  Describe seasonal size and age distributions, reproductive patterns  Gain better understanding of dogfish feeding ecology and food web dynamics  Estimate region specific stock assessment parameters  Estimate GOA abundance from parameters  Build inter-agency cooperation

65 Other dogfish projects  Tagging study  Dean Courtney, NMFS $200 REWARD For Electronic Tags in Spiny Dogfish Not to Scale

66 Other dogfish projects  Stable Isotope/Feeding Ecology  Alex Andrews, UAF  Socioeconomics of a potential fishery  Jason Gasper, UAF  Creel census and bycatch sampling with ADF&G

67 Thanks!  NPRB  NMFS AFSC  NMFS Auke Bay Lab  Dean Courtney, Chris Lunsford, Brian VanWinkle, Dave Clausen, Mitch Lorenz  ADF&G  Willy Dunne, Ken Goldman, Bob Johnson, Scott Meyer, Tory O’Connell, Scott Pegau, Charlie Stock, Charlie Trowbridge, Mike Vaughn, Gordie Woods  F/V Alaskan Leader  F/V Kingfisher-Chris and Natalie Ekstrom, Kyle Dickerson  F/V Sea View-John Ethridge  F/V Winter King-Rex Murphy, Holly VanPelt, Mikey  F/V Ocean Prowler


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