PFRP PI Meeting 2008
David Itano1, Kim Holland2 and Kevin Weng3
1 Pelagic Fisheries Research Program, University of Hawaii at Manoa 2 Hawaii Institute of Marine Biology, University of Hawaii, 3 University of Hawaii at Manoa, School of Earth Science Technology Hawaii Tuna Tagging Project (1995- 2001) (archipelagic scale, conventional dart tags for Movementbigeyeof bigeye and yellowfin and yellowfin tuna) within the Hawaii EEZ and between major fishing grounds. (exchange rates)
Interaction à direct gear interaction / concurrent interaction à sequential or growth interactions à spatially segregated interaction
Exploitation rates and differential vulnerability (local fishing mortality) of tuna around seamounts and FADs
Aggregation effects - retention rates of bigeye and yellowfin tuna around seamounts, FADs and local HTTP: objectives and outcomes
17,986 bigeye and yellowfin tagged @ 53:47 ratio à 12.6% overall recapture rate
Bulk transfer model developed to describe tag loss by all means … between offshore FADs/seamount, inshore areas and offshore LL fishery à Estimated transfer (movement) rates à Estimated size and species-specific M and F rates
Calculated residence times and exploitation rates
Provided a closer definition of fisheries and exploitation patterns 150 E 160 E 170 E 180 170 W 160 W 150 W 140 W 40 N
USA JAPAN 30 N MEXICO
Minami Tori HAWAII Shima
Wake 20 N CNMI (US) Johnston (US)
Guam Marshall Islands
10 N Federated States of Micronesia Palmyra Palau (US)
Howland & Indonesia Nauru Kiribati Baker Jarvis 0 Papua New Guinea (US) Line Phoenix Islands Islands (Kiribati) (Kiribati) Tuvalu Solomon Islands 10 S WF SamoaAmerican Fiji Samoa Cook Islands Australia Vanuatu French Polynesia New Niue 20 S Caledonia Tonga Pitcairn (U.K.) New Zealand 180 170W 160W 150W 140W
Yellowfin in red Bigeye in blue 30N
20N
Johnston
10N
Palmyra
Line Islands 160 W 155 W Necker NOAA B-1
Nihoa Main Hawaiian Islands Kauai
Niihau Oahu
Kaula Kaena Pt. Rock Molokai / Lanai / Maui Penguin Bank
Bigeye 1 20 N
Keahole Pt. Hilo Bay Hawaii NOAA B-3 Cross Seamount South Point
NOAA B-4 NOAA B-2 Meanwhile, changes in Hawaii-based tuna fisheries A decline: in effort in the surface fisheries for juvenile bigeye and yellowfin on the Cross Seamount and offshore weather buoys;
The development and expansion of a deep-set short longline fishery on the Cross Seamount to target larger bigeye tuna and seamount associated pomphrets;
An increase in the setting and exploitation of privately set FADs close to the main Hawaiian islands, primarily aggregating and harvesting sub-adult bigeye tuna;
increased harvesting of very small yellowfin tuna from the inshore Hawaii State FADs;
A steady increase in tuna longline effort by the domestic fishery due to conversion of swordfish effort and a steadily increasing number of hooks per tuna directed set.
Increasing fuel costs The HTTP 2: Justification
HTTP concentrated on interaction issues relevant to the Cross Seamount and offshore weather buoy fishery (YF and BE)
The Cross seamount handline fishery has evolved, shifting to short longline gear and multi-species targeting
Nearshore issues relevant to Hawaii domestic fisheries remain unresolved
Need to update movement parameters, M and F estimates and examine AREAS and SPECIES under-represented during the HTTP
Lack of knowledge of skipjack resources when they may become increasingly important to local fisheries
Continued uncertainty as to the ‘connectivity’ of tropical tuna between Hawaii and the broader WCPO biomass HTTP2: objectives
1) update estimates of fishing mortality (F), ‘natural’ mortality (M) and movement parameters for yellowfin and bigeye tuna in Hawaiian waters while deriving initial estimates of M and F and movement parameters for skipjack. à To include a continuation of existing PFRP tagging projects to define the typical home range for “Hawaiian” tuna using sonic, archival and PAT tags, à … with a greater emphasis on areas and species under- represented during HTTP, i.e. bigeye tuna found around the main Hawaiian Islands and targeted by the private FAD fishery, and yellowfin and skipjack tuna on FADs and near shore aggregation sites,
à … with increased emphasis on tagging unassociated or near shore bank associated tuna schools with both conventional dart and acoustic tags. HTTP2: objectives
2) Document the FAD-associated temporal and vertical behavior of skipjack tuna. à Using acoustic pinger and depth reporting tags on receiver equipped FADs with à … simultaneous releases with yellowfin and bigeye tuna to provide species-specific comparisons in mixed aggregations.
3) Determine the diurnal vertical behavior of bigeye tuna and lustrous pomphret (Eumegistis illustris) associated with the Cross Seamount.
à Using acoustic depth reporting tags on all three species in simultaneous seamount residence, à … which will require deployment of acoustic receivers on bottom- mounted acoustic release systems. a comparison between HTTP and HTTP2 Project outline
Species à Skipjack, yellowfin, bigeye, lustrous pomphret (Eumegistis illustris) Tag types (conventional, acoustic, archival, PAT) Release sites à State anchored FAD system à Private bigeye FADs à Banks (koas) à Open water areas à Cross Seamount Release timetable à 2 years, start late 2008 Project outline Tagging platforms Fishing gears and methods Key personnel à Holland, Itano, Weng Data processing and analysis à Integrated with PTTP Oahu R
Honolulu
20 km Cross Seamount
Pomphret funding from NMFS 20km 40km
0m
200m
400m 38kHz
600m
0m
200m 120kHz
400m
19:00 21:00 23:00 Cross Seamount acoustic images (R. Domokos, NMFS) 120kHz 38kHz Cross Seamount acoustic 21:30 20km images (R. Domokos, NMFS) 22:30 25km 23:00 30km 1000m 200m 200m 800m 600m 400m 400m 0m 0m Cross Seamount acoustic tagging and imaging
2km 4km
200m
400m 38 kHz
600m
11:40 12:00
Cross Seamount acoustic images (R. Domokos, NMFS) Nearshore FAD Issues Interrupt normal movement routes ? Decrease catches in traditional koas and fishing grounds ? Increases vulnerability of very small tuna “Burn out” an area, reduce productivity ? Private FADs à Selectivity à Seasonality à Bigeye behavior SPC – PACIFIC TUNA TAGGING PROJECT
Cruise 1 and Papua New Guinea Central Pacific: Tuna Tagging Project Cruise 1
HTTP 2
Cruise 1 Cruise 2: Micronesia, Marshall Islands to Wallis and Futuna Mahalo