application of the dumb tag technology

Transcription

1 Aggregation, exploitation and scales of spatial variability... of bigeye and yellowfin tuna in the Central Pacific:. application of the dumb tag technology

2 Hawaii Tuna Pelagic Fisheries Research Program University of Hawaii Tagging Project David Itano Kim Holland Steve Kajiura Gary Eldridge Randy Kosaki Gary Dill

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4 Necker 160 W 155 W Nihoa Main Hawaiian Islands Kauai Niihau Oahu? Molokai / Lanai / Maui 20 N Hawaii???

5 30 N Fishing grounds - the Hawaiian Ridge 25 N Kure Midway Atoll Pearl & Hermes Salmon Bank Lisianski Northwest Hawaiian Islands Laysan Maro Reef Gardner Pinnacles French Frigate Necker B1 Nihoa Offshore weather buoys Inshore FADs Isolated reef or atoll Main Hawaiian Islands 20 N Kaula Rock Bigeye 1 B3 Cross Seamount Johnston Atoll B2 B4 15 N W 170 W 165 W 160 W 155 W 150 W

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7 Hawaii s Tuna Fisheries Longline Bigeye, yellowfin, albacore Pole-and-line Skipjack, yellowfin Troll Yellowfin, skipjack Charter, commercial, combination recreational/subsistence/p-t commercial Handline Yellowfin, bigeye, albacore Palu ahi - daytime handline (med Yellowfin) Ika shibi - night time handline (large Yellowfin) Offshore handline (small/medium Bigeye, yellowfin)

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11 Tag releases and recaptures (HTTP to October 31, 2000) Bigeye Yellowfin Total Releases Recaptures Recapture Rate 14.99% 13.12% 14.08%

12 30 N Fishing Grounds & Tag release areas Midway Atoll Northwest Hawaiian Islands 200 mile Exclusive Economic Zone NWHI Longline prohibited zone MHI Longline prohibited zones Throughout the year October 1 - January N B1 Main Hawaiian Islands 20 N Johnston Atoll B3 Cross Smt B4 B2 15 N W 170 W 165 W 160 W 155 W

13 Length Frequency of releases 3000 Number of fish BE YF >130 Fork Length (cm) Range Median Mode Mean Std Dev Count BE YF

14 Area Midway Recaptures from releases made at these areas Total releases BE return rate (%) YF return rate (%) Total return rate (%) % 0.8 % 0.8 % B1 - Nihoa I. Oahu FADs Big Island FADs Offshore FADs Cross Seamount NMFS Archival % 14.6 % 14.8 % % 26.0% 25.7% % 15.9 % 15.9 % % 21.8 % 18.5 % % 18.7% 15.4% % NA 15.6 %

15 Necker NOAA B-1 Nihoa 160 W Movements from offshore 155 W FADs Main Hawaiian Islands Kauai Niihau Oahu Kaula Rock Kaena Pt. Molokai / Lanai / Maui Penguin Bank Bigeye 1 20 N Keahole Pt. Hawaii Hilo Bay NOAA B-3 Cross Seamount South Point NOAA B-2 NOAA B-4

16 Necker NOAA B-1 Nihoa Yellowfin and bigeye movements 160 W 155 W from Cross Seamount Main Hawaiian Islands Kauai Niihau Oahu Kaula Rock Kaena Pt. Molokai / Lanai / Maui Penguin Bank Bigeye 1 20 N Keahole Pt. Hawaii Hilo Bay NOAA B-3 Cross Seamount South Point NOAA B-2 NOAA B-4

17 Movements from Cross Seamount 35 N 30 N 25 N 20 N 15 N 170 W 160 W 150 W 140 W 130 W 10 N 120 W

18 Necker NOAA B W To Big Island 155 W Nihoa Main Hawaiian Islands Kauai Niihau Oahu Kaula Rock Kaena Pt. Molokai / Lanai / Maui Penguin Bank Bigeye 1 20 N Keahole Pt. Hawaii Hilo Bay NOAA B-3 Cross Seamount South Point NOAA B-2 NOAA B-4

19 All recaptures by association Bigeye 741 Yellowfin 645 Total 1386 % of Total Seamount Offshore 63.3% FAD Inshore FAD % 11.7% Bank or Koa Unassociated Total % 2.9%

20 Main Hawaiian Island recaptures by association Un Log FAD Bank or koa Total BE YF Total % of Total 1.9 % 1.3 % 82.6 % 14.2 %

21 150 E 160 E 170 E W 160 W Midway releases JAPAN 30 N Minami Tori Shima HAWAII CNMI Wake Johnston 20 N Guam Marshall Islands 10 N Palau Federated States of Micronesia Palmyra Line Islands PNG Nauru Kiribati Howland & Baker Jarvis 0

22 150 E 160 E 170 E W 160 W 150 W 140 W 130 W JAPAN All recaptures Minami Tori Shima HAWAII 30 N USA Mexico CNMI Wake Johnston 20 N Guam Marshall Islands 10 N Palau Federated States of Micronesia Palmyra Indonesia PNG Nauru Kiribati Howland & Baker Phoenix Islands Jarvis Line Islands 0 Solomon Islands Tuvalu Tokelau 10 S Australia New Caledonia Vanuatu Fiji W&F Cook Islands SamoaAm Samoa Tonga Niue French Polynesia Pitcairn

23 Recaptures by gear and flag Gear Type Area Fleet Bigeye Yellowfin Total Mix HL/Troll Inshore HW Mix HL/Troll Offshore HW Handline Inshore Ika shibi HW Pole and line Inshore HW Pole and line Offshore JP Longline Offshore JP Longline Cross HW Longline Offshore HW Purse seine Mexico US

24 points of interest Significance of Aggregation and Vulnerability Seamounts FADs Inshore aggregation areas or Ahi Koas Role of Hawaiian Archipelago as FADs relatively local behavior of bigeye and yellowfin Large data set on Cross Seamount estimates of interaction, residency, exchange rates, N, F Bigeye - wandering offshore, between different vulnerability points, and then?? Yellowfin - inshore and offshore movement?

25 Cross Seamount tag attrition rates 80 % recovery be yf More Days at liberty

26 Mean size of recaptures by fishery 125 Mean fork length (cm) Bigeye Yellowfin 0 Pole and line HL/Troll Inshore HL/Troll Cross HL Ika shibi LL Cross LL Offshore Fishery

27 Depth distributions from archival and sonic tags Bigeye Yellowfin

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29 What do we have? Species specific data for BET and YFT Fine scale recapture date and location and school aggregation Ability to track the vulnerability of both species, seasonally and by area as they grow and recruit to different fisheries = data for analyses

30 Relevant publications Holland, K.N., Kleiber, P., Kajiura, S.M., Different residence times of yellowfin tuna, Thunnus albacares, and bigeye tuna T. obesus, found in mixed aggregations over a seamount. Fish Bull. 97, Itano, D.G., and K.N. Holland Movement and vulnerability of bigeye (Thunnus obesus) and yellowfin tuna (T. albacares) in relation to FADs and natural aggregation points. Aquat. Living Resour. 13:1-11. Sibert, J., Holland, K., and D. Itano Exchange rates of yellowfin and bigeye tunas and fishery interaction between Cross Seamount and nearshore FADs in Hawaii. Aquat. Living Resour. 13: Holland, K.N., S. M. Kajiura, D.G. Itano and J. R. Sibert Tagging techniques can elucidate the biology and exploitation patterns of aggregated pelagic fishes. Proceedings of the Symposium on the Charleston Bump. Trans. Am. Fish. Soc. (In Press).

31 NMFS archival tagging of bigeye

32 FAD Tagging

33 Keep those tags coming!! Thanks to: PFRP Hawaii s fishermen United Fishing Agency Midway Phoenix Corporation National Marine Fisheries Service, Honolul Department of Aquatic Resources US Fish and Wildlife Service NMFS Pago Pago, American Samoa Secretariat of the Pacific Community Forum Fisheries Agency Inter-American Tropical Tuna Commission National Research Institute of Far Seas Fisheries (Japan) National Fisheries Research & Developmen Institute (Rep of Korea) National Taiwan University

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