SCRS/2008/103

STANDARDIZED BLUEFIN CPUE FROMTHE JAPANESE LONGLINE FISHERY IN THE ATLANTIC UP TO 2007

K. Oshima, Y. Takeuchi and N. Miyabe1

Summary

Abundance indices from the Japanese longline fishery in the Atlantic including the Mediterranean Sea were provided up to 2007. Indices were developed for three areas; west Atlantic, central Atlantic and east Atlantic including Mediterranean Sea. The indices were standardized with delta-normal model with random effect. West Atlantic index exhibited considerable fluctuation without any trend. The abundance in the east Atlantic had fluctuated until the early 1980s and then exhibited a decline reaching the lowest point in 1996. It recovered since then and 2001 data point located at about a half of what it was during the early 1980s. Abundance index from the central Atlantic was high in 1996 but went down thereafter and stayed at about the average level in 2001.

Key Words Bluefin tuna, stock abundance, catch and effort, CPUE standardization, Generalized Linear Mixed Model, delta-lognormal model, longlining

Introduction The Japanese longline fishery is very unique in its operation. Namely, it has long and wide coverage of the bluefin distribution in the Atlantic as well as in the Mediterranean Sea (the geographical coverage) by this fishery (Fig. 1). These facts are considered the most important advantages in providing abundance trend for this species. Longline fishery is often considered passive gear and there is less factors to be considered in the standardization of CPUE than the other active gears such as purse seine. Nonetheless, there has been many changes in its fishing areas, seasons and operational modes, which make the interpretation of CPUE from this fishery difficult. Fortunately, most of information necessary for that has been obtained from this fishery. Since the 1998 assessment session of ICCAT, additional variances were estimated for the west Atlantic 1 NRIFSF. 5-7-1, Orido, Shimizu, Shizuoka, 424-8633. Japan. oshimaka@affrc.go.jp

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index by means of treating some interaction terms as random variable (Anon. 1999). This paper provides updated abundance trend of the bluefin stocks in the Atlantic (Miyabe 1993, 1995, 1997, 2001 and Miyabe and Takeuchi 1999) through the CPUE standardization by the application of Generalized Linear Modeling technique.

Data Data were extracted from the Japanese longline fishery catch and effort data compiled from logbook data by the National Research Institute of Far Seas Fisheries (NRIFSF) from 1976 to 2007. Information on number of hooks between floats (NHBF) were recorded since 1975. Data on materials for main and branch lines were available since 1994. The catch and effort data were disaggregated, namely, set by set (daily) data. Generally speaking, data coverage has been high at more than 90 %. The period for which standardization was conducted was determined by the magnitude of bluefin catches in each area. The catch history by the Japanese longline fishery dates back to much earlier period but those data before the mid 1970s were mostly came from different areas (mostly tropical waters) from the current fishing grounds and there was no size data accompanied. It should be noted that the fleets are very mobile and have modified their operational practice and fishing technique. In this study, CPUE from this fishery was standardized for traditional three areas where fishing was currently taking place; west Atlantic (off US and Canadian coast north of 35° N), central Atlantic (between 45°W and 5°E and north of 38°N to 65°N in the east Atlantic), and east Atlantic (30 to 40N, off Gibraltar to western Mediterranean Sea). The indices of these three areas are hereafter referred to as west, central and east indices. Central index is shorter in its history and has started since around 1990. The other two have a longer history since the mid 1970s. The area covered by central index was extended towards east to 5°E in longitude in order to cover data that was not used at the last analysis. Similarly, the area for the east index was slightly expanded to cover some marginal data. The size of fish caught and fishing season are different in these areas. These are the reasons why the indices are estimated separately. In general, the size of fish are small to medium (130-180cm), medium large (>170 cm) and large (>200 cm) for west, central and east indices, respectively. Similarly, the fishing season is November to February, August to March, and March to July for the same areas. Age(s) specific CPUEs were not estimated due to several reasons. In some cases there are not enough size data. Actually, size samples were strengthened by the effort of the Japanese

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Government. However, many data were provided by various sources including industry as well as the Marine Research Institute of Iceland (Ms. Droplaug Olafsdottir pers. comm.) Thanks to the Icelandic authority for allowing us to use size data measured on the Japanese boats operated in the Icelandic water. These data were used to develop catch-at-size.

Dimension of CPUE/Area

West Central East (including

Mediterranean Sea)

Years 1976-2007 1990-2007 1975-2007

Month Nov.-Feb. Aug.- Mar. Mar.-Jul.

Beginning or mid-year

Beginning Beginning Mid-year

Geographical extent

30-50N, 45-80W (Fig. 3, upper

panel, areas 1-24)

38-65N, 30-45W 40-65N, 5E-30W

(Fig. 3, upper panel, areas 31-35)

30-45N,45W-25E (Fig. 3, lower

panel, areas 1-9)

Number of sets is tabulated in Tables 1 – 3 by year, season, area, materials for the main and branch lines, and NHBF. Total number of observations extracted are 57,566 (west CPUE area), 78,456 (central CPUE area) and 61,214 (east CPUE area). During the recent years, the largest observation was exerted in the central CPUE area and has increased for the past 5 to 6 years. The number of observation is declining especially in November and December in west CPUE area, while that of February and March increased. This is due to some shift of fishing effort to the central Atlantic in November and earlier closure of fishing season by reaching quota. Area of fishing has shifted since around 1990 primarily due to a closure of fishing in US EEZ. The fishing season in the central CPUE area has become earlier year after year, and fishing has declined after December. The changes in fishing gear were similar among three areas; nylon material has become major material for both main and branch lines, and hooks between floats increased slightly from 4-6 to 7-8.

Methods This paper followed the CPUE standardization methods in the last assessment (Miyabe et al 2006). Year, month, area (Fig. 4), main, bran and NHBF were considered as main effects in our model and an interaction between month and area was maintained as a random effect. Information on material for main and branch lines is only available since 1994 and classified as either nylon or other materials. For data before 1994 it was assumed that all were other materials. In order to keep the interaction in the model, some observations in neighboring strata (month and area) were aggregated. Categories in each main effect adopted in the model are shown below. Delta-lognormal model (Lo et al. 1992) was applied for standardizing CPUE in this study, because the database used included many zero-catch

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observations. Formula of logistic regression model of the 1st step model is as follows:

Log Intercept Year Month + Area +Main + Bran + NHBF + Month*Area+ Error1

pp= + +

− (1)

where Log(p/(1 − p)) is logit function, p indicates ratio of positive catch; Main, Bran refers to materials of main and branch lines, respectively; and error is assumed to be distributed binomially. The formula of lognormal model of the 2nd step is as follows:

Log CPUE Intercept + Year + Month +Area +Main + Bran +NHBF +Month*Area + Error= (2)

where LogCPUE indicates natural logarithm of catch rate, that is number of PBF per 1000 hooks; Main and Bran effects are the same as one in the 1st step; and error is also assumed to be distributed normally. The fitting was conducted by GLIMMIX macro and MIXED procedure of SAS/STAT package (Version 9.1) for the 1st and 2nd step, respectively.

Main effect / Area West Central Atlantic East Atlantic (Area 5 + Med.)

Year 1976-2007 1990-2007 1975-2007

Season (month) Nov, Dec, Jan, Feb Aug.-Nov, Dec, Jan, Feb+Mar

Mar, April, May, June

Area 5 areas (Fig. 3) 5 areas (Fig. 3) 6 areas (Fig. 3)

Material of main line Nylon, others (since 1994)

Nylon, others (since 1994)

Nylon, others (since 1994)

Material of branch line Nylon, others (since 1994)

Nylon, others (since 1994)

Nylon, others (since 1994)

Hooks between floats 5– 13 (individual) 4 - 7, 8 - 12 hooks 4 - 7, 8 - 13 hooks

Results and discussion Results of type 3 test for positive catch ratio (1st step) and CPUE of positive catch (2nd step) are shown in Table 4. All the main effects except for year and NHBF are not always significant at 5% significant level. Over-dispersion was observed in the 1st step with large dispersion parameters of 4.33, 5.08 and 5.16 in the west, central and east Atlantic, respectively. Consequently, it might be necessary to incorporate additional random effect such as vessel ID (individual difference) in order to reduce over dispersion. Residual patterns of positive CPUE in the 2nd step were slightly skewed and indicated right-tailed shape (Fig. 4). Additionally, the residual distribution in the central Atlantic had two modes. There were large fluctuations in observed and predicted proportions of positive catch in West Atlantic

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(Fig. 5). Annual proportion in West increased after 2005 and remained high until 2007. On the contrary, the proportions in Central and East Atlantic showed flat yearly trend compared to that in the west. Observed CPUE of positive catch in the east and west Atlantic fluctuated without any trend during 1976 – 2007 and it increased remarkably in 2007 in the west (Fig. 6). On the other hand, CPUE in the central Atlantic exhibited flat trend. Standardized CPUE based on the Least Square Mean are shown in Figure 7. In the west Atlantic, the abundance showed gradual decrease with large fluctuation from 1976 to the early 1980s reaching the lowest in 1986. It recovered since then and exhibited slight increase after 2001. In 2007, it had increased remarkably, but the confidence interval in this year was wider than those in other years. This increase and wide confidence interval might be due to the small number of observation in 2007 (Table 1). Therefore, estimated CPUE for 2007 is considered to have low reliability. Overall abundance in the east Atlantic showed considerable fluctuation. The abundance in the east Atlantic declined after 1976 as well as that in the west and reached the lowest in 1996. After that, it increased and in 2001, recovered at the equivalent level to that in the early 1980s in 2001. In 2006, it increased again after a decline during the 2001 – 2004, but it again declined in 2007. In the central Atlantic, the abundance index reached the highest value in 2006 and decreased thereafter and remained at the average level since 1999.

References Lo, NC-H, Jacobson, LD, Squire, JL. 1992. Indices of relative abundance from fish spotter data based

on delta-lognormal models. Can. J. Fish. Auat. Sci. Vol. 49, no. 12, pp. 2515-2526. Anon. 1999. Report of the ICCAT SCRS bluefin tuna stock assessment session (Genoa, Italy –

September 14 to 23, 1998). Bluefin tuna – Detailed Report. ICCAT, Col. Vol. Sci. Pap., 46(2):1-191.

Anon. 2001. Report of the ICCAT Workshop on bluefin mixing. SCRS/01/020. 32pp.

Miyabe, N. 1993. Standardized CPUE of Atlantic bluefin in the eastern Atlantic and Mediterranean Sea obtained from the Japanese longline fishery. ICCAT, Col. Vol. Sci. Pap., 40(2):310-316.

Miyabe, N. 1995. Updated standardized CPUE of Atlantic bluefin caught by the Japanese longline fishery in the eastern Atlantic and Mediterranean Sea. ICCAT, Col. Vol. Sci. Pap., 44(1):335-339.

Miyabe, N. 1997. Updated standardized CPUE of Atlantic bluefin caught by the Japanese longline fishery in the Atlantic. ICCAT, Col. Vol. Sci. Pap., 46(2):102-117.

Miyabe, N. and Y. Takeuchi. 1999. Updated Atlantic Bluefin CPUE from the Japanese longline fishery

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in the Atlantic. ICCAT Col. Vol. Sci. Pap., 46(1):130-140.

Miyabe, N. and Y. Takeuchi 2003. Standardized bluefin CPUE from the Japanese longline fishery in the Atlantic and Mediterranean Sea up to 1999. ICCAT, Col. Vol. Sci. Pap., 52:1130-1144.

Miyabe, N. and Y. Takeuchi 2006. Standardized bluefin CPUE from the Japanese longline fishery in the Atlantic and Mediterranean Sea. SCRS/2006/97.

SCRS/2008/103

Table 1 Number of longline sets by various strata for West Atlantic CPUE standardization. Observations were aggregated by month, area (prefixed by A), materials of main line (M1=others, M2=nylon) and branch line (F1=others, F2=nylon), number of hooks between floats (prefixed by B). Area definition is shown in Fig. 3. Year is fishing year.

Year Nov Dec Jan Feb A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12 A131976 347 322 266 208 9 1 0 0 0 0 0 0 163 196 2 0 01977 551 545 561 238 3 5 2 0 0 0 0 10 85 542 176 0 01978 516 559 388 56 0 4 0 5 0 0 0 3 208 244 98 0 21979 755 680 758 179 0 2 0 0 0 0 0 24 242 774 122 0 191980 1103 1083 683 170 0 9 0 0 0 0 0 4 152 321 131 54 01981 1554 1573 905 341 0 0 0 0 0 0 0 17 237 404 339 220 101982 1778 843 206 116 1 1 1 0 0 0 0 35 336 206 133 52 01983 806 620 546 425 0 0 1 0 0 0 0 0 151 170 200 10 01984 619 599 549 217 0 0 0 0 0 0 0 0 45 175 71 9 11985 723 873 677 358 0 0 0 0 0 0 0 0 76 287 55 5 01986 688 641 551 53 0 0 0 0 0 0 0 0 19 129 85 5 361987 912 944 710 42 0 30 11 0 21 7 0 0 10 318 287 1 01988 891 869 651 364 0 1 0 0 0 10 0 0 27 458 507 41 111989 807 1078 530 247 0 0 1 126 333 51 0 0 3 198 344 6 01990 673 782 765 301 0 0 5 57 299 81 0 0 0 63 171 37 151991 516 491 541 169 0 0 0 20 40 133 4 0 0 9 18 51 51992 313 719 398 2 0 0 0 0 41 21 3 0 0 6 9 1 101993 664 622 343 53 0 0 0 0 0 0 0 0 0 4 5 2 01994 336 575 533 92 0 0 0 0 0 0 0 0 0 17 9 9 261995 239 217 112 1 0 0 0 0 0 0 0 0 0 0 25 3 01996 41 371 70 0 0 11 0 0 0 0 2 0 0 0 11 0 01997 73 614 133 0 0 0 0 0 6 34 28 0 0 0 3 0 01998 31 747 375 33 0 0 17 0 26 5 0 0 0 8 79 1 31999 337 649 295 157 0 0 3 90 107 77 114 0 0 0 1 4 22000 347 568 204 153 0 0 0 23 99 31 112 0 0 2 5 0 02001 190 688 245 164 0 12 1 67 250 128 146 0 0 0 0 1 22002 646 841 327 398 0 22 7 96 245 393 159 0 0 27 29 0 72003 166 503 131 174 0 112 10 5 126 181 117 0 0 0 0 0 32004 41 158 506 258 0 72 2 77 173 77 99 0 0 30 42 5 12005 10 243 851 806 5 195 0 118 204 127 64 0 0 543 124 5 12006 0 152 612 430 18 140 4 89 208 173 47 0 0 39 165 2 02007 2 17 32 46 4 9 0 0 0 0 0 0 0 21 13 5 1Total 16675 20186 14454 6251 40 626 65 773 2178 1529 895 93 1754 5191 3259 529 155

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Table 1 cont.

Year A14 A15 A16 A17 A18 A19 A20 A21 A22 A23 A24 M1 M2 F1 F2 B4 B51976 0 14 268 19 7 442 19 0 0 3 0 1143 0 1143 0 0 9711977 0 5 90 197 175 520 85 0 0 0 0 1895 0 1895 0 108 14741978 0 5 24 186 54 677 8 0 0 1 0 1519 0 1519 0 22 13991979 11 9 105 472 83 474 35 0 0 0 0 2372 0 2372 0 4 19431980 3 3 70 1060 657 550 25 0 0 0 0 3039 0 3039 0 584 19891981 3 6 201 844 559 1290 214 0 0 0 29 4373 0 4373 0 91 26501982 0 0 46 67 198 1534 322 0 0 0 11 2943 0 2943 0 16 12231983 0 0 50 845 158 752 38 0 0 0 22 2397 0 2397 0 77 5731984 2 0 51 945 251 342 86 0 0 0 6 1984 0 1984 0 0 4321985 1 1 212 577 187 1063 164 0 0 1 2 2631 0 2631 0 55 431986 11 0 23 326 67 977 236 0 0 0 19 1933 0 1933 0 0 211987 0 0 170 669 241 662 161 0 0 2 18 2608 0 2608 0 0 261988 0 0 311 786 258 344 11 0 0 0 10 2775 0 2775 0 0 51989 0 0 126 414 416 504 113 0 0 1 26 2662 0 2662 0 39 01990 0 0 59 461 515 585 128 0 0 0 45 2521 0 2521 0 10 01991 0 0 103 357 172 601 121 0 0 11 72 1717 0 1717 0 40 151992 2 0 16 172 215 629 163 0 1 1 142 1432 0 1432 0 34 01993 0 0 13 352 378 849 67 0 0 0 12 1682 0 1682 0 0 361994 0 0 6 308 245 630 282 0 0 0 4 1525 11 1464 72 1 251995 1 0 0 220 95 146 75 0 0 0 4 514 55 382 187 0 331996 0 0 25 54 15 138 177 0 0 0 49 151 331 192 290 0 01997 3 0 7 58 29 251 186 0 0 0 215 109 711 195 625 0 11998 30 0 0 154 38 224 355 0 0 0 246 156 1030 163 1023 0 01999 3 0 0 14 23 366 427 0 0 0 207 76 1362 193 1245 73 02000 1 0 1 166 48 493 235 0 0 0 56 39 1233 83 1189 0 02001 0 0 0 1 3 270 112 0 0 1 293 6 1281 19 1268 0 02002 10 0 0 14 14 314 230 0 0 0 645 70 2142 168 2044 0 02003 13 0 0 2 5 108 209 0 0 0 83 0 974 0 974 0 02004 0 0 0 18 10 64 273 0 0 0 20 79 884 32 931 7 02005 5 0 20 42 91 172 194 0 0 0 0 66 1844 229 1681 0 02006 0 0 1 132 17 73 72 0 0 0 14 18 1176 100 1094 0 02007 0 0 0 3 15 24 0 0 0 0 2 0 97 0 97 0 0Total 99 43 1998 9935 5239 16068 4823 0 1 21 2252 44435 13131 44846 12720 1161 12859

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Table 1 cont.

Year B6 B7 B8 B9 B10 B11 B12 B13 B14 B15 B16 B17 B18 B19 B20 B21 Total1976 172 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 11431977 313 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 18951978 95 0 0 0 3 0 0 0 0 0 0 0 0 0 0 0 15191979 378 28 0 0 19 0 0 0 0 0 0 0 0 0 0 0 23721980 384 51 28 0 3 0 0 0 0 0 0 0 0 0 0 0 30391981 998 279 94 107 154 0 0 0 0 0 0 0 0 0 0 0 43731982 781 180 116 136 334 117 40 0 0 0 0 0 0 0 0 0 29431983 1242 117 174 0 209 0 5 0 0 0 0 0 0 0 0 0 23971984 1345 70 20 6 65 19 6 0 0 5 16 0 0 0 0 0 19841985 1414 987 0 25 6 3 46 49 3 0 0 0 0 0 0 0 26311986 742 831 198 0 59 5 0 77 0 0 0 0 0 0 0 0 19331987 1083 1269 138 10 30 0 27 0 25 0 0 0 0 0 0 0 26081988 115 2326 275 0 14 0 10 30 0 0 0 0 0 0 0 0 27751989 383 1777 270 14 108 21 50 0 0 0 0 0 0 0 0 0 26621990 382 1961 132 0 17 0 14 0 0 5 0 0 0 0 0 0 25211991 147 1165 277 0 1 1 0 45 25 1 0 0 0 0 0 0 17171992 219 830 279 26 14 0 0 3 3 5 19 0 0 0 0 0 14321993 295 1066 208 25 46 0 6 0 0 0 0 0 0 0 0 0 16821994 175 1048 197 76 0 0 14 0 0 0 0 0 0 0 0 0 15361995 2 191 207 76 28 28 0 0 4 0 0 0 0 0 0 0 5691996 15 127 237 91 9 0 0 0 0 3 0 0 0 0 0 0 4821997 22 166 344 131 53 68 0 34 0 0 0 1 0 0 0 0 8201998 0 322 645 85 101 32 0 0 0 0 0 0 0 0 0 1 11861999 59 129 855 47 108 0 53 21 37 56 0 0 0 0 0 0 14382000 3 120 639 256 116 51 33 48 0 6 0 0 0 0 0 0 12722001 6 133 808 61 162 20 20 7 0 50 8 0 12 0 0 0 12872002 0 60 1398 369 205 2 127 29 3 0 0 19 0 0 0 0 22122003 0 26 333 259 85 1 64 0 0 89 72 5 40 0 0 0 9742004 0 105 442 231 47 0 0 0 0 16 33 11 58 0 0 13 9632005 2 12 704 923 73 0 32 29 19 80 13 0 23 0 0 0 19102006 0 2 471 431 78 0 48 17 12 16 35 0 84 0 0 0 11942007 0 0 3 87 7 0 0 0 0 0 0 0 0 0 0 0 97Total 10772 15378 9492 3472 2154 368 595 389 131 332 196 36 217 0 0 14 57566

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Table 2 Number of longline sets by various strata for Central Atlantic CPUE standardization. Observations were aggregated by month, area (prefixed by A), materials of main line (M1=others, M2=nylon) and branch line (F1=others, F2=nylon), number of hooks between floats (prefixed by B). Area definition is shown in Fig. 3. Year is fishing year.

Aug Sep Oct Nov Dec Jan

Year Feb Mar A31 A32 A33 A34 A35 M1 M2 F1 F2 B3 B41990 0 0 61 206 308 195 143 23 930 0 6 0 0 936 0 936 0 0 01991 6 82 241 742 1147 360 158 28 2761 0 3 0 0 2764 0 2764 0 16 01992 0 75 776 1800 1310 546 193 31 4537 179 15 0 0 4731 0 4731 0 105 791993 16 355 1219 1372 878 349 61 15 1334 2600 77 254 0 4265 0 4265 0 0 291994 0 25 473 933 769 390 152 17 1573 1185 1 0 0 2738 21 2647 112 79 01995 0 119 293 646 459 134 27 0 314 259 232 873 0 1300 378 854 824 0 01996 61 610 1228 931 255 0 0 0 289 454 3 2339 0 945 2140 997 2088 1 01997 166 2051 1671 1573 130 15 0 0 996 1062 46 3502 0 1007 4599 1232 4374 0 01998 651 1469 2297 1849 68 3 0 0 316 928 8 5021 64 683 5654 720 5617 4 01999 1205 1827 1945 685 145 10 0 0 287 715 4 4474 337 383 5434 1031 4786 114 02000 877 1510 1838 1594 1168 49 24 0 1884 941 79 3974 182 561 6499 489 6571 6 02001 637 1230 1685 1679 158 148 78 96 920 1282 15 3447 47 297 5414 326 5385 3 02002 490 1070 1643 868 159 92 29 26 1202 678 22 2357 118 188 4189 542 3835 0 02003 270 941 1390 949 36 0 0 18 139 141 39 3255 30 125 3479 194 3410 0 02004 610 1252 1625 1536 1160 23 0 0 361 333 866 4644 2 420 5786 360 5846 75 02005 262 1113 1723 1947 1427 132 0 12 738 135 2569 3174 0 362 6254 604 6012 0 02006 256 825 1479 1490 1096 110 3 81 967 365 978 3030 0 226 5114 595 4745 0 02007 22 148 534 415 354 88 0 3 133 18 740 673 0 95 1469 95 1469 0 0Total 5529 14702 22121 21215 11027 2644 868 350 19681 11275 5703 41017 780 22026 56430 23382 55074 403 108

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Table 2 cont.

9

Year B5 B6 B7 B8 B9 B10 B11 B12 B13 B14 B15 B16 B17 B18 B19 B20 B21 Total1990 6 326 458 77 45 24 0 0 0 0 0 0 0 0 0 0 0 9361991 87 929 980 415 82 133 55 17 5 37 3 0 0 0 5 0 0 27641992 170 2165 1534 428 34 113 0 36 0 2 5 52 5 0 0 3 0 47311993 93 3445 508 25 26 30 6 73 13 0 10 0 2 5 0 0 0 42651994 17 2125 400 5 0 0 0 133 0 0 0 0 0 0 0 0 0 275919 5 68 741 474 280 115 0 0 0 0 0 0 0 0 0 0 0 0 16781996 0 156 1639 1089 198 2 0 0 0 0 0 0 0 0 0 0 0 30851997 0 253 3039 1967 193 55 8 10 0 12 16 0 0 53 0 0 0 56061998 59 21 4352 1698 174 4 8 17 0 0 0 0 0 0 0 0 0 63371999 1 184 2451 2814 60 47 0 48 0 0 79 19 0 0 0 0 0 58172000 1 76 2682 4004 254 13 0 24 0 0 0 0 0 0 0 0 0 70602001 0 49 2054 3231 212 86 5 71 0 0 0 0 0 0 0 0 0 57112002 0 0 637 3463 201 61 15 0 0 0 0 0 0 0 0 0 0 43772003 1 1 333 2957 312 0 0 0 0 0 0 0 0 0 0 0 0 36042004 0 1 706 4618 673 124 5 0 0 0 0 4 0 0 0 0 0 62062005 7 2 392 5231 910 59 0 0 0 0 15 0 0 0 0 0 0 66162006 0 0 366 3925 928 109 4 3 0 0 4 0 0 1 0 0 0 53402007 0 0 0 1426 138 0 0 0 0 0 0 0 0 0 0 0 0 1564Total 510 10474 23005 37653 4555 860 106 432 18 51 132 75 7 59 5 3 0 78456

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Table 3 Number of longline sets by various strata for Central Atlantic CPUE standardization. Observations were aggregated by month, area (prefixed by A), materials of main line (M1=others, M2=nylon) and branch line (F1=others, F2=nylon), number of hooks between floats (prefixed by B). Area definition is shown in Fig. 3. Year is fishing year.

Year Mar Apr May Jun Jul A1 A2 A3 A4 A5 A6 A7 A8 A9 M1 M2 F1 F2 B31975 272 770 1611 246 273 862 1369 14 14 232 294 267 115 5 3172 0 3172 0 3421976 148 765 762 118 268 116 938 1 3 81 390 268 259 5 2061 0 2061 0 831977 137 247 503 397 207 151 721 0 10 174 268 157 10 0 1491 0 1491 0 771978 317 307 205 129 12 340 216 4 33 308 21 44 4 0 970 0 970 0 01979 133 201 224 165 48 47 365 0 47 202 37 63 10 0 771 0 771 0 1681980 209 387 323 18 4 268 444 0 7 39 62 104 17 0 941 0 941 0 191981 300 339 190 34 15 269 238 0 1 209 112 45 4 0 878 0 878 0 41982 78 323 585 481 327 27 172 16 43 944 327 261 4 0 1794 0 1794 0 01983 186 612 690 621 195 139 307 0 75 1331 196 243 13 0 2304 0 2304 0 991984 361 947 998 517 271 225 605 3 17 1301 325 500 94 24 3094 0 3094 0 861985 44 693 704 86 42 36 193 58 4 400 71 717 73 17 1569 0 1569 0 531986 143 700 716 122 16 64 517 0 41 519 157 336 63 0 1697 0 1697 0 01987 241 590 429 93 12 112 587 9 6 197 179 229 35 11 1365 0 1365 0 01988 392 909 684 127 56 18 786 56 8 762 227 220 63 28 2168 0 2168 0 01989 239 636 424 80 16 18 737 60 22 370 43 93 51 1 1395 0 1395 0 01990 327 772 613 276 14 213 787 44 84 696 72 102 2 2 2002 0 2002 0 01991 183 739 779 553 60 360 328 44 338 984 157 102 0 1 2314 0 2314 0 251992 200 1057 1132 1038 276 778 209 31 560 1663 256 161 31 14 3703 0 3703 0 1201993 213 799 716 486 134 768 49 46 330 710 68 203 115 59 2348 0 2348 0 131994 182 1134 1093 31 4 666 107 50 354 510 155 280 136 186 1971 473 1639 805 01995 222 1293 1394 284 0 496 502 1 297 1073 378 68 184 194 1807 1386 1349 1844 31996 349 1262 1679 4 50 1145 398 21 252 475 71 552 148 282 784 2560 667 2677 01997 920 1493 1083 24 0 1247 1078 3 357 373 164 201 29 68 530 2990 506 3014 01998 912 1480 856 21 25 547 1493 33 148 470 183 20 100 300 398 2896 503 2791 681999 379 662 667 0 7 149 786 30 77 156 48 18 117 334 89 1626 166 1549 02000 400 577 407 0 0 139 450 22 103 297 12 123 121 117 11 1373 76 1308 02001 248 578 431 0 0 85 287 86 131 214 8 107 131 208 144 1113 81 1176 02002 389 405 771 0 0 441 17 151 53 192 1 217 97 396 107 1458 130 1435 02003 158 431 799 6 0 126 132 53 17 172 6 278 141 469 100 1294 100 1294 02004 33 328 609 2 0 22 67 137 8 130 0 272 171 165 51 921 72 900 02005 346 756 995 1 7 249 401 87 21 211 262 412 462 0 187 1918 222 1883 02006 364 359 308 0 0 189 393 147 6 37 1 258 0 0 77 954 90 941 02007 20 113 165 0 0 4 28 5 0 23 21 217 0 0 64 234 64 234 0Total 9045 22664 23545 5960 2339 10316 15707 1212 3467 15455 4572 7138 2800 2886 42357 21196 41702 21851 1160

- 12 -

03

- 13 -

5 1620 958 252 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 28991976 1278 557 91 0 52 0 0 0 0 0 0 0 0 0 0 0 0 0 17931977 909 265 229 6 0 0 5 0 0 0 0 0 0 0 0 0 0 0 12841978 500 31 77 179 5 46 132 0 0 0 0 0 0 0 0 0 0 0 9581979 438 115 22 15 13 0 0 0 0 0 0 0 0 0 0 0 0 0 7231980 389 226 265 37 5 0 0 0 0 0 0 0 0 0 0 0 0 0 9371981 447 93 189 96 46 0 3 0 0 0 0 0 0 0 0 0 0 0 8631982 1033 454 136 0 0 46 63 6 56 0 0 0 0 0 0 0 0 0 14671983 1622 157 141 43 15 21 180 25 1 0 0 0 0 0 0 0 0 0 21091984 2318 155 285 58 63 22 41 48 6 0 12 0 0 0 0 0 0 0 28231985 1189 112 96 0 0 46 23 37 13 0 0 0 0 0 0 0 0 0 15271986 1360 98 78 51 8 20 8 16 55 0 0 3 0 0 0 0 0 0 16811987 960 128 114 31 66 3 19 10 34 0 0 0 0 0 0 0 0 0 13531988 1912 45 7 21 102 42 0 15 2 0 2 20 0 0 0 0 0 0 21121989 1003 161 60 53 12 21 0 11 12 13 36 11 0 2 0 0 0 0 13791990 947 651 81 63 55 0 4 0 28 82 1 83 3 4 0 0 0 0 19881991 1266 520 296 122 20 0 45 0 2 5 4 0 2 3 0 4 0 0 22541992 1998 663 545 245 80 0 0 3 22 3 3 4 4 0 9 0 4 0 34271993 1248 413 457 54 102 0 6 15 14 3 7 16 0 0 0 0 0 0 22141994 1512 668 232 13 16 0 0 0 1 0 0 0 0 2 0 0 0 0 24401995 551 782 1459 114 171 0 6 0 37 0 26 0 1 5 38 0 0 0 31931996 78 512 1720 771 83 30 19 7 54 23 7 11 0 14 1 14 0 0 32941997 0 72 711 2053 373 88 13 49 23 59 22 22 7 28 0 0 0 0 35201998 0 0 257 2197 723 18 0 0 7 4 0 1 0 2 17 0 0 0 32691999 0 19 172 1317 197 10 0 0 0 0 0 0 0 0 0 0 0 0 17082000 0 27 182 887 213 8 7 0 1 0 0 19 0 0 40 0 0 0 13842001 0 32 173 669 349 27 7 0 0 0 0 0 0 0 0 0 0 0 12572002 0 0 336 750 407 72 0 0 0 0 0 0 0 0 0 0 0 0 15652003 0 0 316 662 303 32 74 0 0 0 0 0 0 0 7 0 0 0 13942004 0 0 128 440 219 79 99 0 0 0 6 0 0 1 0 0 0 0 9722005 0 1 69 508 1260 204 12 0 0 0 22 29 0 0 0 0 0 0 20982006 0 0 0 188 507 180 16 0 42 0 0 10 33 4 51 0 0 0 10312007 0 0 0 181 109 5 0 3 0 0 0 0 0 0 0 0 0 0 298Total 24578 7915 9176 11824 5574 1020 782 245 410 192 148 229 50 65 163 18 4 0 61214

Table 3 cont.

7

Year B4 B5 B6 B7 B8 B9 B10 B11 B12 B13 B14 B15 B16 B17 B18 B19 B20 B21 Total19

SCRS/2008/1

SCRS/2008/103

Table 4 Statistical results from GLMM analysis for positive catch ratio (1st step) and CPUE of positive catch (2nd step). West Atlantic Type 3 test of fixed effect for proportion of positive catch Effect DF DF Chi-square F Value Pr > ChiSq Pr > F

ym area m

branbr

ear 31 278 103.69 3.34 <.0001 <.0001onth 1 278 3.1 3.1 0.0784 0.0795

4 278 59.11 14.78 <.0001 <.0001ain 1 928 0.17 0.17 0.6792 0.6793

1 928 0.22 0.22 0.6359 0.6368 928 177.94 22.24 <.0001 <.0001

Type 3 test of fixed effect for LogCPUE with positive catch Effect DF DF F Value Pr > F

ym

ear 31 261 3.08 <.0001onth 1 261 3.66 0.0569a 4 261 13.1 <.0001

ain 1 29000 23.68 <.0001n 1 29000 0.06 0.8092

8 29000 6.03 <.0001

are m

brabr

Central Atlantic Type 3 test of fixed effect for proportion of positive catch Effect DF DF Chi-square F Value Pr > ChiSq Pr > F

ym

ear 17 179 63.95 3.76 <.0001 <.0001onth 3 179 64.12 21.37 <.0001 <.0001

3 179 42.55 14.18 <.0001 <.0001ain 1 454 1.82 1.82 0.1777 0.1783

1 454 5.53 5.53 0.0186 0.01911 454 18.15 18.15 <.0001 <.0001

area m

brannpb

Type 3 test of fixed effect for LogCPUE with positive catch Effect DF DF F Value Pr > F

ym

ear 17 169 4.29 <.0001onth 3 169 40.62 <.0001a 3 169 1.77 0.1545

ain 1 57000 81.76 <.0001n 1 57000 3.48 0.0621

1 57000 11.44 0.0007

are m

branpb

- 14 -

SCRS/2008/103

Table 4 cont. East Atlantic Type 3 test of fixed effect for proportion of positive catch Effect DF DF Chi-square F Value Pr > ChiSq Pr > F

ym area m

brannpb

ear 32 450 123.02 3.84 <.0001 <.0001onth 3 450 27.05 9.02 <.0001 <.0001

4 450 152.72 38.18 <.0001 <.0001ain 1 471 22.99 22.99 <.0001 <.0001

1 471 0.83 0.83 0.3614 0.36191 471 55.13 55.13 <.0001 <.0001

Type 3 test of fixed effect for LogCPUE with positive catch Effect DF DF F Value Pr > F

ym

ear 32 422 9.65 <.0001onth 3 422 24.71 <.0001a 4 422 21.3 <.0001

ain 1 44000 15.35 <.0001n 1 44000 4.78 0.0287

1 44000 12.98 0.0003

are m

branpb

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SCRS/2008/103

- 16 -

Fig. 1 Monthly distribution of bluefin catch by Japanese longliners by 1-degree square.

SCRS/2008/103

used

Fig. 2 Area definition developed at the workshop on bluefinmixing in 2001. The division between area 4 and 5 (secondline from the top) is used in this study apart from the original

definition.

Fig. 3 Areas considered in the CPUE standardization. Upper panel indicates areastratification used for west CPUE area and central CPUE area. Numbers from 1 through24 and from 31 through 35 denote for these area, respectively. Lower panel shows thesame information for east CPUE area. Numbers indicate original area stratification

in Tables 1-3.

- 17 -

SCRS/2008/103

Fig. 4 Residual distributions in the 2nd steps of CPUE standardization with positive catch. Upper panel, West Atlantic; middle panel, Central Atlantic; lower panel, East Atlantic.

- 18 -

SCRS/2008/103

Fig. 5 Observed and predicted proportion of positive catch observation. Upper panel, West Atlantic; middle panel, Central Atlantic; lower panel, East Atlantic.

- 19 -

SCRS/2008/103

Fig. 6 Observed and predicted CPUE of positive catch set. Upper panel, West Atlantic; middle panel, Central Atlantic; lower panel, East Atlantic.

- 20 -

SCRS/2008/103

Fig. 7 Standardized CPUE with 95% confidence intervals and nominal CPUE. Upper panel, West Atlantic; middle panel, Central Atlantic; lower panel, East Atlantic.

- 21 -