14 th PICES The vertical and horizontal distribution of bigeye tuna (Thunnus( obesus) ) and yellowfin tuna (Thunnus( albacares) ) related to ocean structure Eun Jung Kim 1,2, Suam Kim 1, Dae-Yeon Moon 2 and Jeong-Rack Koh 2 1 Pukyong National University 2 National Fisheries Research & Development Institute
Introduction The tuna fishing area in the Tropical Pacific Longline Fishing area Purse seine Warm pool fishing area NINO3.4 High density area
deph Schematic vertical distribution of tuna tspecies in Pacific
Skipjack tuna & environmental factors E130 E150 E170 W170
Bigeye tuna (Thunnus obesus) Yellowfin tuna (Thunnus albacares)
Objective To find the response of spatial & vertical distribution of bigeye & yellowfin tuna related to the oceanographic condition
Horizontal distribution of bigeye and yellowfin tuna
Fishing data Materials & Methods About 200 Korean longline vessels Jan. 1999 Dec. 2000 Catch numbers of bigeye and yellowfin tuna georeferenced in 5 grids of latitude and longitude. Fishing gravity centre of CPUE(G) FISHING in AREA month j G j = i L i (C ij /E ij )/ i (C ij/ E ij ) www.themegallery.com
Results Seasonal change (3 months) of fishing centroids N 0 Bigeye tuna 2000 jun-aug 1999 mar-may 2000 march-may 1999 jun-aug 1999 sep-nov 2000 sep-nov 1999-2000 dec-feb 5S 170W 160W 150W 140W 130W N Yellowfin tuna 0 2000 jun-aug 1999 mar-may 1999-2000 dec-feb 1999 jun-aug 2000 sep-nov 1999 sep-nov S 2000 march-may 170W 160W 150W 140W 130W
240 130W 230 220 150W 210 200 170W 190 180 170E Results Monthly change of centroids Longitudinal centroids Latitudinal centroids yellowfin 4 bigeye 4N 2N 2 0 2S -2 4S -4 6S -6 Jan-99 Mar-99 May-99 Jul-99 Sep-99 Nov-99 Jan-00 Mar-00 May-00 Jul-00 Sep-00 Nov-00 Jan-99 Mar-99 May-99 Jul-99 Sep-99 Nov-99 Jan-00 Mar-00 May-00 Jul-00 Sep-00 Nov-00 yellowfin bigeye r=0.449 (<0.05) Not significant What causes this change?
Results Longitudinal centroids & SST of NINO3.4 E 130W 230 225 140W 220 215 150W 210 205 160W 200 195 170W 190 Yelloiwfin tuna SST in NINO3.4 Longitudinal centroid of yellowfin 28 27 26 25 24 23 230 225 140W 220 215 210 205 160W 200 195 170W 190 SST in NINO3.4 Longitudinal centroid of bigeye 28 27 26 25 24 23 1999-01 1999-03 1999-05 1999-07 1999-09 1999-11 2000-01 2000-03 2000-05 2000-07 2000-09 2000-11 1999-01 1999-03 1999-05 1999-07 1999-09 1999-11 2000-01 2000-03 2000-05 2000-07 2000-09 2000-11 W r=-0.465 (<0.05) E 130W 150W Bigeye tuna (C ) W (C ) Not significant
Results Seasonal change (3 months) of fishing centroid N 0 Bigeye tuna 2000 jun-aug 1999 mar-may 2000 march-may 1999 jun-aug 1999 sep-nov 2000 sep-nov 1999-2000 dec-feb 5S 170W 160W 150W 140W 130W N Yellowfin tuna 0 2000 jun-aug 1999 mar-may 1999-2000 dec-feb 1999 jun-aug 2000 sep-nov 1999 sep-nov S 2000 march-may 170W 160W 150W 140W 130W
Results Anomaly of SOI (Southern Oscillation Index) with longitudinal centroids E 130W 230 225 140W 220 Longitude 215 150W 210 20 15 10 5 0 SOI 205 160W 200 W 195 170W 190-5 -10-15 Jan-99 Mar-99 May-99 Jul-99 Sep-99 Nov-99 Jan-00 Mar-00 May-00 Jul-00 Sep-00 Nov-00
Vertical distribution of bigeye and yellowfin tuna
Materials & Methods Schematic view of a basket of tuna longline gear Sea surface Float line Float Main line Branch line hook
Materials & Methods Fishing data One fishing vessel, Sinyoung 53 August 1999 October 2000 Catch per hook of 211 sets of longline setting FISHING AREA www.themegallery.com
Materials & Methods to calculate the depth of each hook Yoshihara formula (1951,1954) D j =h a +h b +L{(1+cot 2 φ ) 1/2 -[(1-2j/n) 2 +cot 2 φ ] 1/2 } No. of hook Dept h (m) 1 2 3 4 5 6 7 8 (17) (16) (15) (14) (13) (12) (11) (10) 120-190m 191-260m 261-330m 331-400m 131 164 207 247 286 322 351 372 379 9
Materials & Methods Environmental data (TAO buoy data) (http://www.pmel.noaa.gov/tao/index.html) Subsurface temperature (0-500m)
Results CPUEs of bigeye and yellowfin tuna in four depth 120-190m 191-260m 261-330m 331-400m 0 3 6 9 (No. of fish/1000 hooks) yellowfin bigeye
SOI anomaly August September, 1999 20 15-50 -100-100 10 5 0-5 -10-15 Jan-99 Mar-99 May-99 Jul-99 Sep-99 Nov-99 Jan-00 Mar-00 May-00 Jul-00 Sep-00 Nov-00-150 -200-200 -250-300 -300-350 -400-400 -450-500 -500 1800 1850 1900 1950 2000 2050 2100 2150 2200 2250 2300 2350 160W 150W 140W 130W October April, 1999-2000 May August, 2000-50 -100-100 -150-200 -200-250 -300-300 -350-400 -400-450 -500-500 1800 1850 1900 1950 2000 2050 2100 2150 2200 2250 2300 2350 160W 150W 140W 130W -50-100 -100-150 -200-200 -250-300 -300-350 -400-400 -450-500 -500 1800 1850 1900 1950 2000 2050 2100 2150 2200 2250 2300 2350 160W 150W 140W 130W
Summary Spatial distribution with season was not clear, but catch locations of both species look coherent longitudinally. Bigeye tuna seem to distribute further east than yellowfin tuna. El Niño might affect on the longitudinal fishing grounds of both species. However, yellowfin tuna response more sensitively to the environmental change than bigeye tuna.
Summary Bigeye tuna located in deeper depth than yellowfin tuna. When the SOI was negative (i.e., thermocline was shallow in the western area), the tuna distributions seemed to be located more in the western area, and vice versa. The vertical movement was not clear from our study.
Future study Use of more vertical data over longer period Investigation on distribution of several tuna species under dynamical ocean structure
Part 3. Bait selectivity
Materials & Methods Bait were used Mackerel Horse mackerel Squid Sardine Herring
Results & Discussion 1 0.8 fish/100 baits 0.6 0.4 0.2 0 mackerel horse mackerel squid sardine herring bigeye yellowfin
Results Bait selectivity of bigeye tuna 120-190m 2 3.6 1.8 4.3 2.1 190-260m 5.4 6.9 5.9 6.3 2.7 260-330m 7.2 9 6.8 8.9 8.4 330-400m 7.2 8.4 4.6 7.3 6.2 0 10 20 30 40 50 (no. of fish/1000 bait) mackerel horse mackerel squid sardine herring
Results Bait selectivity of yellowfin tuna 120-190m 3.7 9.3 3.1 4.9 4.2 190-260m 5.2 6.4 4.3 5.8 4.6 260-330m 5.7 6.1 4.1 5.4 3.3 330-400m 2.5 5.1 2.4 5.2 3.1 0 10 20 30 40 (no. of fish/1000 bait) mackerel horse mackerel squid sardine herring
Summary Sardine and horse mackerel are the efficient bait for bigeye and yellowfin tuna. The order of bait efficiency is not change even the depth difference in both species.