Cerviño-López, S. (Santiago)

Domínguez-Petit, R. (Rosario)

Jardim, E.

Saborido-Rey, F.

Sainza-Sousa, M.C. (María del Carmen)

English

Cerviño, S. (Santiago)

Saborido-Rey, F. (Francisco)

Repositorio Institucional Digital del IEO

 1 BENCHMARK 2010   WORKING DOCUMENT ABOUT MATURITY OGIVES ANALYSIS OF EUROPEAN HAKE FROM SOUTHERN STOCK Rosario Dominguez-Petit1, Santiago Cerviño2, Fran Saborido-Rey1, María Saínza2, Ernesto Jardim3  (1) Institute of Marine Research (CSIC). Eduardo Cabello, 6. 36208. Vigo (Spain) (2) Spanish Institute of Oceanography (IEO). Subida a Radio Faro, 50-52. 36390. Vigo (Spain) (3) Institute of Fisheries and Sea Research (IPIMAR). Av. De Brasilia. 1449-006. Lisbon (Portugal).  INTRODUCTION  The Data Collection Regulation (DCR) programme covers extensive sampling of maturity data (Reg EC No1639/2001). The maturity stage is an important biological parameter to be used in the calculation of maturity ogives (and therefore of Spawning Stock Biomass), for the definition of the spawning season of a species, for the monitoring of long-term changes in the spawning cycle, and for many other research needs regarding the biology of fish. Taking into account that the proportion of resting females during the peak of the spawning season is lower than the rest of the year, in the Workshop on Sexual Maturity Staging of Hake and Monkfish, held in Lisbon (Portugal), 21–24 November 2007 it was agreed that maturity ogives should only be based on data collected during the peak of the spawning season (ICES, 2007). Since then, sampling effort has been focused between December and March.   On the other hand, maturity ogives has been traditionally estimated considered both sex together. Nevertheless, it is known that males mature earlier than females, at lower sizes and probably at lower ages too (Alheit and Pitcher, 1995; Ungaro, 2001; Piñeiro and Saínza, 2003).  Overestimation of L50 leads to underestimation of SSB with the consequent impact on assessment and management measures. Because of these, the aim of this study is to estimate maturity ogives using different pool of data (sex combined and only females) from the peak of spawning and from all year around to study effect on L50 estimates and impact on assessment and management.   SAMPLING  All specimens included in this study came from Galician Shelf. The Bay of Biscay, Portugal and the Gulf of Cadiz data were excluded because historical data series are short and/or incomplete. Besides, in the case of the Gulf of Cadiz, historical data presents inconsistent results.  35,598 European hake specimens were caught and sexed during the period 1982-2008 (16,746 males and 18,852 females. Annual distribution of samples was not homogeneous, fluctuating between 143 individuals caught in 1987 and 3067 individuals caught in 2008 (Table 1). Length distribution was not homogeneous either between or within years. In some years most of specimens belongs to the same length range and some sizes were undersampled (Table 2 and 3).  Length-weight relationship was plotted for all year, excepting for those year when weight information was not available. No important differences between annual curves were observed (Figure 1) that means there are no relevant changes between studied years.   2 Table 1: Number of mature and immature males and females sampled per year .  Year Males Females Total Immature Mature Immature Mature 1982 40 168 61 159 428 1983 69 99 103 46 317 1984 216 252 264 277 1009 1985 648 473 628 386 2135 1986 82 154 108 141 485 1987 54 55 32 2 143 1988 456 193 369 80 1098 1989 384 238 322 243 1187 1990 1011 572 1138 186 2907 1991 299 254 406 186 1145 1992 496 131 528 20 1175 1993 170 48 160 21 399 1994 407 160 478 67 1112 1995 591 571 526 106 1794 1996 225 266 369 238 1098 1997 505 158 652 134 1449 1998 330 176 491 55 1052 1999 239 261 369 64 933 2000 179 202 270 124 775 2001 175 96 259 52 582 2002 282 208 603 237 1330 2003 364 585 933 927 2809 2004 170 458 763 930 2321 2005 415 537 772 472 2196 2006 588 496 927 247 2258 2007 95 67 214 18 394 2008 539 839 1203 486 3067 Total 9029 7717 12948 5904 35598  3 Table 2: Sampled males length distribution per year.   Year Length (cm) <5 5-15 15-25 25-35 35-45 45-55 55-65 65-75 75-85 >85 1982 0.00% 0.00% 0.00% 9.50% 58.60% 31.00% 1.00% 0.00% 0.00% 0.00% 1983 0.00% 0.00% 3.00% 41.10% 39.90% 15.50% 0.60% 0.00% 0.00% 0.00% 1984 0.00% 0.00% 4.70% 41.90% 23.50% 27.60% 2.40% 0.00% 0.00% 0.00% 1985 0.00% 0.10% 14.50% 38.20% 38.50% 7.90% 0.70% 0.00% 0.00% 0.00% 1986 0.00% 0.00% 1.30% 32.20% 47.50% 18.60% 0.40% 0.00% 0.00% 0.00% 1987 0.00% 0.00% 0.00% 26.10% 55.90% 16.20% 1.80% 0.00% 0.00% 0.00% 1988 0.00% 1.50% 30.40% 43.90% 20.90% 3.20% 0.00% 0.00% 0.00% 0.00% 1989 0.00% 0.00% 32.30% 30.70% 23.60% 13.00% 0.30% 0.00% 0.00% 0.00% 1990 0.00% 0.50% 37.10% 34.70% 22.10% 5.40% 0.30% 0.00% 0.00% 0.00% 1991 0.00% 0.00% 28.20% 30.60% 27.50% 13.50% 0.30% 0.00% 0.00% 0.00% 1992 0.00% 0.00% 31.80% 40.20% 22.20% 5.40% 0.50% 0.00% 0.00% 0.00% 1993 0.00% 0.20% 37.50% 35.10% 22.00% 5.20% 0.00% 0.00% 0.00% 0.00% 1994 0.00% 12.20% 24.60% 33.60% 26.40% 3.00% 0.10% 0.00% 0.00% 0.00% 1995 0.00% 0.00% 22.20% 40.60% 32.00% 4.90% 0.20% 0.00% 0.00% 0.00% 1996 0.00% 0.20% 18.70% 26.80% 42.50% 11.70% 0.20% 0.00% 0.00% 0.00% 1997 0.00% 1.10% 32.20% 35.10% 26.10% 4.90% 0.60% 0.00% 0.00% 0.00% 1998 0.00% 0.00% 31.50% 39.00% 24.80% 4.50% 0.20% 0.00% 0.00% 0.00% 1999 0.00% 1.50% 18.10% 32.90% 44.80% 2.70% 0.00% 0.00% 0.00% 0.00% 2000 0.00% 2.00% 24.90% 34.50% 34.60% 3.40% 0.50% 0.00% 0.00% 0.00% 2001 0.00% 0.00% 32.50% 35.00% 27.50% 5.00% 0.00% 0.00% 0.00% 0.00% 2002 0.00% 0.00% 32.40% 30.40% 33.20% 3.80% 0.20% 0.00% 0.00% 0.00% 2003 0.00% 0.20% 10.60% 38.30% 42.10% 8.30% 0.50% 0.00% 0.00% 0.00% 2004 0.00% 0.00% 12.80% 39.40% 38.20% 7.70% 1.80% 0.10% 0.00% 0.00% 2005 0.00% 0.00% 10.90% 41.90% 42.30% 4.40% 0.40% 0.00% 0.00% 0.00% 2006 0.00% 0.10% 24.70% 35.90% 30.30% 8.80% 0.30% 0.00% 0.00% 0.00% 2007 0.00% 0.00% 39.30% 35.00% 21.50% 4.30% 0.00% 0.00% 0.00% 0.00% 2008 0.00% 0.00% 19.30% 37.40% 29.00% 13.10% 1.10% 0.00% 0.00% 0.00%   4 Table 3: Sampled females length distribution per year.  Year Length (cm) <5 5-15 15-25 25-35 35-45 45-55 55-65 65-75 75-85 >85 1982 0.00% 0.00% 0.00% 8.60% 7.20% 26.70% 52.90% 4.50% 0.00% 0.00% 1983 0.00% 0.00% 2.00% 61.70% 5.40% 6.70% 22.10% 2.00% 0.00% 0.00% 1984 0.00% 0.00% 2.20% 43.30% 9.10% 17.60% 26.40% 1.30% 0.20% 0.00% 1985 0.00% 0.00% 15.50% 30.20% 15.70% 21.20% 16.70% 0.70% 0.00% 0.10% 1986 0.00% 0.00% 1.60% 25.70% 14.10% 32.50% 23.70% 2.40% 0.00% 0.00% 1987 0.00% 0.00% 0.00% 32.30% 21.00% 1.60% 21.00% 16.10% 6.50% 1.60% 1988 0.00% 0.70% 27.60% 45.20% 17.10% 7.10% 2.20% 0.00% 0.00% 0.00% 1989 0.00% 0.20% 25.50% 23.50% 9.40% 28.50% 11.90% 1.10% 0.00% 0.00% 1990 0.00% 0.10% 38.90% 35.90% 16.80% 5.90% 1.90% 0.40% 0.00% 0.00% 1991 0.00% 0.00% 25.90% 31.20% 15.30% 21.90% 5.80% 0.00% 0.00% 0.00% 1992 0.00% 0.00% 37.80% 40.10% 17.30% 2.70% 1.60% 0.40% 0.00% 0.00% 1993 0.00% 0.00% 36.70% 36.50% 16.70% 7.30% 2.40% 0.20% 0.00% 0.00% 1994 0.00% 0.20% 22.00% 38.30% 27.20% 9.30% 2.90% 0.00% 0.20% 0.00% 1995 0.00% 0.00% 17.70% 39.80% 29.50% 6.90% 4.70% 1.40% 0.10% 0.00% 1996 0.00% 0.00% 15.10% 18.50% 33.60% 22.50% 8.50% 1.80% 0.00% 0.00% 1997 0.00% 0.70% 23.10% 30.70% 22.80% 14.00% 6.50% 1.60% 0.50% 0.00% 1998 0.00% 0.20% 19.40% 37.20% 26.40% 12.60% 3.40% 0.90% 0.00% 0.00% 1999 0.00% 0.40% 22.40% 21.70% 40.70% 11.20% 3.40% 0.20% 0.00% 0.00% 2000 0.00% 1.00% 22.00% 30.40% 25.50% 15.20% 5.30% 0.80% 0.00% 0.00% 2001 0.00% 0.00% 32.80% 29.80% 21.40% 11.40% 3.60% 0.90% 0.00% 0.00% 2002 0.00% 0.00% 17.00% 23.50% 28.40% 26.80% 4.20% 0.00% 0.10% 0.00% 2003 0.00% 0.10% 7.90% 16.70% 22.00% 26.50% 24.90% 1.90% 0.10% 0.00% 2004 0.00% 0.00% 4.80% 17.10% 21.50% 32.50% 20.80% 2.90% 0.50% 0.00% 2005 0.00% 0.00% 9.50% 31.10% 22.10% 21.00% 14.20% 1.80% 0.20% 0.10% 2006 0.00% 0.10% 21.30% 35.70% 18.00% 18.60% 6.20% 0.00% 0.10% 0.00% 2007 0.00% 0.00% 39.40% 12.30% 11.20% 26.40% 9.90% 0.80% 0.00% 0.00% 2008 0.00% 0.10% 16.20% 27.60% 21.10% 23.40% 10.40% 1.10% 0.10% 0.10%   Figure 1: Annual length-weight relationships (1982-2008) both sexes combined.  a)  Length (cm)Total WYear: 1982Year: 1983Year: 1984Year: 1985Year: 1986Year: 1987Year: 1988Year: 1989Year: 1990Year: 1991Year: 1992Year: 1993Year: 1994Year: 1995Year: 1996Year: 1997Year: 1998Year: 1999Year: 2000Year: 2001Year: 2002Year: 2003Year: 2004Year: 2005Year: 2006Year: 20070 10 20 30 40 50 60 70 80 90-1000010002000300040005000600070008000    5 MATURITY OGIVES (1982-2008)  To estimate maturity ogives all data were checked and those outliers considered sampling errors were removed. Maturity ogives were estimated considering different pools of data:  - Maturity females data from all year around whose length was extrapolated to length at 1st January using growth parameters estimated with tagging data from IFREMER:  L∞ 128.35 K 0.168 to -0.215 b -0.1544298 a 19.8215949   - Maturity females data considering only specimens caught between December of year i-1 and March of year i.  - Maturity males and females combined data considering only specimens caught between December of year i and March of year i+1.   Data were fit to logistic model:  bLabLaeeP  1   Where P is the probability to be mature and L is length in cm. Mean maturity length (L50) was estimated as:  baL 50   Table 4 shows both logistic curve parameters and L50 estimated for each year using the four different pool of data. Differences of L50 estimated using different methods can be higher than 10 cm, depending on individuals size distribution, sex proportion and/or considered months and growth rates.  Figure 2 shows annual variation of L50 based on samples from December to March from both, sex combined and only females maturity data. As expected, due to earlier maturation of males, L50 was significantly lower if males were included in maturity ogives estimates.  When L50 based on female length data extrapolated to 1st January using both sets of growth parameters were compared to L50 estimated based on December to March female data, temporal trends were rather different. The highest differences between L50 (> 5 cm in 8 years from 28 years serie) were observed when ogives estimated using female length at 1st January based on fast growth parameters and ogives estimated using only females caught between December and March were compared. Variations between other methods, in general, did not show differences higher than 5 cm. Differences might be due to sampling effort. Before 2007, sampling was not focused on the peak of spawning, so, in some years number of sampled females caught between December and March was scarce, length biased or even nonexistent. Since 2003, because of the existence of different research projects focused on hake, database is more exhaustive and complete; this may explain why data are more similar during this period.  Figure 3 shows that L50 based on females does not show the same trend when both methods are compared.     6 Table 4: Annual logistic curve parameters and L50 basing on different methods.   Year Length at Jan-1 (fast growth) Dec-Mar females Dec-Mar mixed a b L50 a b L50 a b L50 1980 -13.696 0.273 50.3       1982 -17.788 0.395 45.0 -41.742 0.942 44.3 -22.973 0.623 36.9 1983 -12.917 0.321 40.2 -13.567 0.332 40.9 -18.373 0.547 33.6 1984 -11.241 0.306 36.8 -19.513 0.455 42.9 -17.457 0.467 37.3 1985 -15.207 0.400 38.0 -27.787 0.663 41.9 -19.800 0.612 32.4 1986 -11.969 0.317 37.8 -25.621 0.579 44.3 -13.595 0.376 36.2 1987          1988 -11.356 0.359 31.7 -63.354 1.623 39.0 -12.536 0.420 29.9 1989 -9.676 0.272 35.6 -58.744 1.517 38.7 -11.097 0.310 35.8 1990 -7.259 0.198 36.6 -14.603 0.357 40.9 -15.008 0.427 35.2 1991 -8.190 0.238 34.4 -57.894 1.505 38.5 -23.621 0.697 33.9 1992 -15.414 0.433 35.6 -12.684 0.295 42.9 -14.511 0.443 32.8 1993 -16.046 0.433 37.1       1994 -9.137 0.232 39.4 -11.703 0.269 43.5 -11.820 0.330 35.8 1995 -8.952 0.218 41.1 -12.516 0.270 46.4 -9.243 0.250 36.9 1996 -4.905 0.123 40.0 -17.968 0.495 36.3 -12.423 0.378 32.9 1997 -10.089 0.225 44.9 -12.166 0.285 42.6 -9.502 0.276 34.4 1998 -7.253 0.156 46.6 -26.276 0.660 39.8 -18.349 0.521 35.2 1999 -7.567 0.187 40.5 -12.284 0.268 45.8 -5.361 0.178 30.2 2000 -18.276 0.459 39.8 -106.428 2.516 42.3 -14.059 0.377 37.3 2001 -11.942 0.277 43.1 -10.689 0.239 44.8 -10.269 0.249 41.3 2002 -5.752 0.148 38.9       2003 -11.863 0.288 41.2 -24.466 0.555 44.1 -4.598 0.146 31.5 2004 -7.160 0.179 40.0 -10.031 0.207 48.5 -4.280 0.120 35.7 2005 -7.568 0.196 38.7 -33.343 0.765 43.6 -6.429 0.181 35.6 2006 -7.821 0.183 42.7 -12.170 0.281 43.4 -11.163 0.330 33.9 2007 -11.087 0.269 41.2 -9.259 0.201 46.1 -2.816 0.067 42.0 2008 -9.914 0.240 41.4 -29.431 0.686 42.9 -8.342 0.235 35.5      7 Figure 2: Annual L50 based on individuals sampled between December of year i and March of year i+1. Orange line represents L50 based just on females and red line represents L50 based on both sexes.  1980 1985 1990 1995 2000 2005 2010L50253035404550   Figure 3: Annual L50 based on: a) female length at the 1st January calculated using fast growth parameters (red line) and length of females sampled between December of year i and March of year i+1 (orange line).  1975 1980 1985 1990 1995 2000 2005 2010L50303540455055    CONCLUSIONS  Differences in L50 (>10 cm) estimates has been observed depending on method. Historical data collecting was not focused on the peak of spawning, so, the reconstruction of data series based on this criteria is difficult. However, since 2003, when hake database was more complete, differences in L50 were lower.  - The use of new growth parameters leads to L50 decreasing between 3 and 5 cm depending on the year, affecting to SSB figures and trends.  -Two methods for female maturity estimation were tested. One with yearly maturation corrected to first of January and other, based on data collected during the peak of the spawning season following ICES (2007), recommendations. The second one has the disadvantage  of scarce data some years. Preliminary results shows that both methods produce different trends. Further work is needed to decide the better one.  On the other hand, maturity ogives has been traditionally estimated combining both sex maturity data, but attending the present results, this proxy leads to different trends and a reduction of estimated L50, that may bias  SSB estimations.    8  FUTURE ACTIONS Nowadays, the three laboratories involved in hake assessment: AZTI, IPIMAR and IEO, are taking histology samples to validate macroscopic maturity ogives. Even historical data series from the Bay of Biscay and Portugal are short and incomplete, this information is very important to improve maturity ogive estimates (Domínguez-Petit et al. In press).   Next step will be to repeat this study using data from the Bay of Biscay and Portugal in the framework of small scale project focused in data from the last 3-5 years.  Considering that individuals from these two areas belong to the same stock that Galician specimens, results should be similar. If so, all combined data could be considered in the assessment. Different results would indicate spatial difference within the stock, and then, it would be necessary consider these areas separately.  The objective of this work would be to compare L50 estimates between different calculation methods within and between areas, and to analyze their implications in the European hake Southern Stock assessment and management.   REFERENCES  - Alheit, J. and T.J. Pitcher. 1995. Hake: fisheries, ecology and markets. Chapman & Hall. London. Fish and Fisheries Series. Vol. 15. 478pp.  - Domínguez-Petit, R., Saínza, M., Silva, L and Morgado, C. In press. Importance of histological information in the assessment of Southern Stock of European hake. Marine and Coastal Fisheries..  - ICES. 2007. Report of the Workshop on Sexual Maturity Staging of Hake and Monk (WKMSHM), 21–24 November 2007, Lisbon, Portugal. ICES CM 2007/ACFM:34. 82 pp.  - Piñeiro, C. and M. Saínza. 2003. Age estimation, growth and maturity of the European hake (Merluccius merluccius) from Iberian Atlantic waters. ICES Journal of Marine Science. Vol. 60: 1068-1102.  - Ungaro, N.; N. Vrgoc and P. Mannini. 2001. The biology and stock assessment of Merluccius merluccius (L.) in the Adriatic Sea: an historical review by geographical management units. FAO Scientific Cooperation to Support Responsible Fisheries in the Adriatic Sea (Adriamed). Italia.: 12pp.   

Maturity Ogives Analysis of European Hake from Southern Stock

Domínguez-Petit, Rosario

Cerviño, Santiago

Saborido-Rey, Francisco

Sainza-Sousa, María del Carmen

Digital.CSIC

http://www.repositorio.ieo.es/e-ieo/bitstream/10508/3584/1/WD3_shke_MaturityHake_Dominguezatal.pdf

Maturity Ogives Analysis of European Hake from Southern Stock

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