The GIS method application for the stock assessment of walleye pollock and the Northeast Arctic cod O.A. Bulatov, B.N.Kotenev, G.S.Moiseenko,, V. M. Borisov Federal Research Institute of Fisheries and Oceanography (VNIRO), Moscow, Russia
Objective: to assess the fishable biomass of walleye pollock and NE Arctic cod in 1998-2007
VESSELS DAILY REPORT (VDR) INCLUDE FOLLOW INFORMATION: DATE OF REPORT LATITUDE LONGITUDE TARGET SPECIES CATCH AMOUNT TYPE OF FISHING VESSEL TYPE OF FISHING GEAR TIME OF THE FISHING OPERATIN
NUMBER OF VDRs SUBMITTED FOR THE SURVEYED AREA IN 1998-2007 ( (walleye pollock) YEAR The Sea of Okhotsk 1998 4,694 1999 3,527 2000 3,748 2001 3,294 2002 2,301 2003 3,517 2004 1,808 2005 3,192 2006 2,557 2007 2,809 Total 31,447
NUMBER OF VDRs SUBMITTED FOR THE SURVEYED AREA IN 2000-2007 2007 ( (NE Arctic cod, Barents Sea) Year \ Number of VDRs Total number of VDRs Number of VDRs with the known trawl type Percentage of VDRs with the known trawl type (%) 2000 36,797 14,458 39.3 2001 31,118 13,220 42.5 2002 23,716 11,236 47.4 2003 20,095 11,052 55.0 2004 22,111 13,712 62.1 2005 21,746 10,969 50.5 2006 25,485 14,381 56.5 2007 (IY-YIII) 15,647 10,766 68.8 Total 196,715 99,794 50,7
DIFFERENCES BETWEEN GIS 1.1 AND GIS 1.2 VERSIONS GIS 1.1 VERSION (POLLOCK) GIS 1.2 VERSION (COD) VESSEL TYPE ALL LARGE VESSELS 8 TYPES OF MEDIUM VESSELS (SELECTED FROM 17) TRAWL TYPE 8 TYPES OF MIDWATER TRAWLS (SELECTED FROM 12) 6 TYPES OF BOTTOM TRAWLS (SELECTED FROM 35) CATCHABILITY COEFFICIENT 0.4 0.3
NUMBER OF VESSELS' DAILY REPORTS VS VESSEL TYPES ( (NE Arctic cod) 6000 5000 number of VDR 4000 3000 2000 2000 2001 2002 2003 2004 2005 2006 1000 0 SRTM nonserial TSM Orlyonok (pr. 333) SRTR Barentsevo more (pr. 1332) SRTM Zheleznyi potok (pr. 502Э) SRTM Vasily Yakovenko (pr. 502ЭМ) vessel type STR Alpinist (pr. 503) SRTM Barentsevo more (pr. 1332) SRTM Ivan Shanykov (pr. 2198)
P n i i = 1 k = Qi ( q x ); P - is the fishable biomass, tons; Q(i) - is the area of each square (i), km²; x(i) - is the mean actual catch in each square (i), t/h of trawling; q - is the area of trawling (determined through multiplication of the trawl horizontal opening by the distance covered), km² k - is the catchability coefficient (which totaled for walleye pollock 0.4 (Shuntov et al., 1988) and for cod 0.3 (Serebrov, 1988). Areas of polygons (each square) were determined with the GIS software ArcView 3.2 (ESRI) The monthly biomass was found as the arithmetic mean biomass for 10-days periods (pollock) and 15-days period (cod)
2000 DENSITY DISTRIBUTION (t/h( t/h) ) OF WALLEYE POLLOCK IN THE SEA OF OKHOTSK IN MARCH 140.00 150.00 160.00 2005 140.00 150.00 160.00 50.00 55.00 60.00 2001 140.00 150.00 160.00 50.00 55.00 60.00 50.00 55.00 60.00 2006 140.00 150.00 160.00 50.00 55.00 60.00
The grid of ichthyoplankton stations in the Sea of Okhotsk (April-June) 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 138 140 142 144 146 148 150 152 154 156 158 160 162
ASSESSMENT OF FISHABLE BIOMASS BY GIS AND SPAWNING BIOMASS BY ICHTHYOPLANKTON METHODS ( (walleye pollock,, the Sea of Okhotsk,, thousands ton) B AVERAGE = 4416 B AVERAGE = 2874
ASSESSMENT OF FISHABLE BIOMASS OF WALLEYE POLLOCK IN THE NORTH OF OKHOTSK SEA BY DIFFERENT METHODS (thousands ton)
FISHABLE BIOMASS AND CATCH OF NORTHEAST ARCTIC COD IN 1977-2006, thousands ton (data from AFWG Report 2007) BMAX BMAX cmax cmax REMAX
DENSITY DISTRIBUTION OF NORTHEAST ARCTIC COD IN BARENTS SEA 0.00 10.00 20.00 30.00 40.00 50.00 60.00 2002 0.00 10.00 20.00 30.00 40.00 50.00 60.00 2004 75.00 75.00 70.00 70.00 65.00 65.00 1-15th July 1-15th July 0.00 10.00 20.00 30.00 40.00 50.00 60.00 2002 0.00 10.00 20.00 30.00 40.00 50.00 60.00 2004 75.00 75.00 70.00 70.00 65.00 65.00 16-31th July 16-31th July
DENSITY DISTRIBUTION OF NORTHEAST ARCTIC COD IN THE BARENTS SEA (2007) 1-15th July 1-15th August 16-31th July 16-31th August
MONTHLY MEAN AND AVERAGE FISHABLE BIOMASS OF ARCTIC COD, '000 t B AVE = 2.32 MIL. T APRIL-DECEMBER 2000-2006 APRIL-AUGUST 2007 B AVE = 2.97 MIL. T
ASSESSMENT OF THE FISHABLE BIOMASS OF NE ARCTIC COD IN 2000-2007 2007 (April-August) August) BY GIS METHOD AND IN 2000-2006 2006 BY XSA METHOD B = 2443 B = 1290
ASSESSMENT OF TOTAL ALLOWABLE CATCH (TAC) OF NE ARCTIC COD IN THE BARENTS SEA, thousands ton TAC AVE = 700 TAC AVE = 431
ASSESSMENT OF SPAWNING BIOMASS OF ARCTIC COD BY TRIPLE ISVPA AND XSA METHODS IN 2000-2006 2006 (thousands ton) AVERAGE BTISVPA = 562.8 AVERAGE BXSA = 442.9 21% 35% 64% 9% 13% 6% 8%
The stock assessment of walleye pollock, thousands ton Method The North Okhotsk Sea GIS (BULATOV, MOISEENKO, IN PRESS) PRESS XSA (SHERSHENKOV, MAGADANNIRO) Dynamic model (BABAYAN, VASILYEV, VNIRO) 2233 (2002-2007) 2007) 1407 (2002-2006) 2006) 1796 (2002-2007) 2007)
The stock assessment of Northeast Arctic cod in the Barents Sea in 2000-2007, 2007, thousands ton Method GIS (BULATOV ET AL., 2007) TISVPA (VASILYEV, BULGAKOVA, 2007) XSA (ICES AFWG Rep., 2007) Fishable biomass 2443 (2000-2007) 2007) 1632 (2000-2006) 2006) 1290 (2000-2006) 2006) Spawning biomass - 563 (2000-2006) 2006) 443 (2000-2006) 2006)
Conclusions In 2007 the fishable biomass of walleye pollock in the Okhotsk Sea and NE Arctic cod in Barents Sea according to the GIS method estimations exceeded 5.7 mln.. t and 3.0 mln t, respectively. Based on the new pollock and cod biomass the TAC could reach 1.2 mln t and 1.0 mln t, respectively, in 2007. However, recommended TAC for walleye pollock based on ichthyoplankton method was 0.5 mln t. and for cod based on XSA method was 0.4 mln t.
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