Aggregation, exploitation and scales of spatial variability... of bigeye and yellowfin tuna in the Central Pacific:. application of the dumb tag technology
Hawaii Tuna Pelagic Fisheries Research Program University of Hawaii Tagging Project David Itano Kim Holland Steve Kajiura Gary Eldridge Randy Kosaki Gary Dill
Necker 160 W 155 W Nihoa Main Hawaiian Islands Kauai Niihau Oahu? Molokai / Lanai / Maui 20 N Hawaii???
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 180 175 W 170 W 165 W 160 W 155 W 150 W
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)
Tag releases and recaptures (HTTP to October 31, 2000) Bigeye Yellowfin Total Releases 7665 7469 15134 Recaptures 1140 980 2131 Recapture Rate 14.99% 13.12% 14.08%
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 31 15 N B1 Main Hawaiian Islands 20 N Johnston Atoll B3 Cross Smt B4 B2 15 N 180 175 W 170 W 165 W 160 W 155 W
Length Frequency of releases 3000 Number of fish 2500 2000 1500 1000 500 BE YF 0 20-29 30-39 40-49 50-59 60-69 70-79 80-89 90-99 100-109 110-119 120-129 >130 Fork Length (cm) Range Median Mode Mean Std Dev Count BE 29-133 58 53 61.45 14.37 9181 YF 20-143 55 48 58.05 17.52 7960
Area Midway Recaptures from releases made at these areas Total releases BE return rate (%) YF return rate (%) Total return rate (%) 2257 0 % 0.8 % 0.8 % B1 - Nihoa I. Oahu FADs Big Island FADs Offshore FADs Cross Seamount NMFS Archival 244 20.0 % 14.6 % 14.8 % 738 23.5% 26.0% 25.7% 1261 15.7 % 15.9 % 15.9 % 3074 17.5 % 21.8 % 18.5 % 9606 13.5% 18.7% 15.4% 77 15.6 % NA 15.6 %
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
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
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
Necker NOAA B-1 160 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
All recaptures by association Bigeye 741 Yellowfin 645 Total 1386 % of Total Seamount Offshore 63.3% FAD 354 40 Inshore FAD 85 216 439 256 20.1% 11.7% Bank or Koa Unassociated Total 4 40 1179 40 23 1009 44 63 2188 2.0% 2.9%
Main Hawaiian Island recaptures by association Un Log FAD Bank or koa Total BE 2 3 40 4 49 YF 4 1 216 40 261 Total 6 4 256 44 310 % of Total 1.9 % 1.3 % 82.6 % 14.2 %
150 E 160 E 170 E 180 170 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
150 E 160 E 170 E 180 170 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
Recaptures by gear and flag Gear Type Area Fleet Bigeye Yellowfin Total Mix HL/Troll Inshore HW 31 144 175 Mix HL/Troll Offshore HW 1044 717 1761 Handline Inshore Ika shibi HW 9 32 41 Pole and line Inshore HW 3 86 89 Pole and line Offshore JP 0 1 1 Longline Offshore JP 8 7 15 Longline Cross HW 59 1 60 Longline Offshore HW 33 9 42 Purse seine Mexico US 0 1 1 1187 998 2185
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?
Cross Seamount tag attrition rates 80 % recovery 70 60 50 40 30 20 10 be yf 0 30 60 90 120 150 180 210 240 270 300 330 360 More Days at liberty
Mean size of recaptures by fishery 125 Mean fork length (cm) 100 75 50 25 Bigeye Yellowfin 0 Pole and line HL/Troll Inshore HL/Troll Cross HL Ika shibi LL Cross LL Offshore Fishery
Depth distributions from archival and sonic tags Bigeye Yellowfin
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
Relevant publications Holland, K.N., Kleiber, P., Kajiura, S.M., 1999. Different residence times of yellowfin tuna, Thunnus albacares, and bigeye tuna T. obesus, found in mixed aggregations over a seamount. Fish Bull. 97, 392-395. Itano, D.G., and K.N. Holland. 2000. 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. 2000. 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. 2000. 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).
NMFS archival tagging of bigeye
FAD Tagging
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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