Castro, J. (José)

García, D. (Dorleta)

Patiño-Alonso, B. (Baltasar)

English

Repositorio Institucional Digital del IEO

WD presented at Benchmark Workshop on Southern Megrim and Hake (WKSOUTH) ICES, Copenhagen, Denmark, 3–7 February 2014  Compilation of LPUE series of the Spanish set-longline fleet targeting hake in non-Spanish European waters Castro1, J., D. García2 and B. Patiño1 1 Instituto Español de Oceanografía (IEO): jose.castro@vi.ieo.es 1 AZTI-Tecnalia    ABSTRACT During the last WGHMM, a problem was identified in the assessment of northern hake in relation to the scarce information on abundance of large fish in the setting of the SS3 model. So, the inclusion of LPUEs from commercial fleets catching adults, i.e. longline or gillnet, was proposed as a possible solution to be investigated. The current working document provides the compilation of LPUE series of the Spanish set-longline fleet targeting hake in ICES Subarea VII. This fleet is compounded of vessels larger than 100 gross registered tonnes (grt) which develop a homogeneous fishing strategy targeting hake alongside the slope of the European western shelf. Although the number of hooks used by trip is not available throughout the time series, the stability of the set-longline fishing tactic makes reasonable to use fishing days as suitable effort unit.   INTRODUCTION The Spanish set-longline fleet operating in non-Spanish European waters is currently composed of two fleet segments whose fishing rights were established under the “Adhesion Treaty of Spain to the European Community” in 1985 (Castro et al., 2011). The first fleet segment is formed by vessels larger than 100 gross registered tonnes (grt) which are allowed to operate in European western waters (ICES Subareas VI and VII, and Divisions VIIIabd), and whose fishing activity is mainly focused on exploiting hake (Merlucius merluccius).  The second fleet segment includes vessels smaller than 100 grt which are restricted to operate in non-Spanish waters of the Bay of Biscay (ICES Divisions VIIIc). Besides, these vessels develop more diverse fishing tactics exploiting not only hake but also conger (Conger conger) or deep-water species as forkbeards (Phycis spp.) and lings (Molva spp.). During the last WGHMM, a number of problems were identified in the assessment of northern hake in order to be analyzed during the WKSOUTH benchmark (ICES, 2013). One of them makes reference to the little information on abundance of large fish in the present setting of the SS3 model. So, the incorporation of CPUE from commercial fleets catching adults, i.e. longline or gillnet, was proposed as a possible solution to be investigated during the benchmark. IEO has been providing to ICES landings, effort and LPUE for the Spanish set-longline fleet operating in Subarea VII for three Galician ports: Burela, Celeiro and A Coruña. However, this data was presented in annual bases, with the only objective to give LPUE series to illustrate trends of hake abundance. 1  WD presented at Benchmark Workshop on Southern Megrim and Hake (WKSOUTH) ICES, Copenhagen, Denmark, 3–7 February 2014 Therefore, the compilation of length frequency distribution (LFD) of quarterly landings of the Spanish set-longline fleet targeting hake in ICES Division VII was developed as inter-seasonal work between WGHMM 2013 and WKSOUTH 2014 meetings.  MATERIAL AND METHODS A dataset was compiled from the commercial data sampled by IEO for the Spanish set-longline fleet operating in ICES Subarea VII: length frequency distribution (LFD), landings and effort by quarter and landing port. Four were the main ports covered, three in Northern Galicia (Burela, Celeiro and A Coruña) and one in Asturias (Avilés). This last one was irregularly covered, so the respective time series was rejected from the final compilation. Length frequency distribution could only be recovered backwards to middle 90’s, so the final Spanish longline LPUE series ranges from 1995 to 2012. RESULTS A Coruña set-longline fleet shows a pronounced decrease in effort since the beginning of the time series (2016 fishing days in 1995 to an average of 300 fd throughout the period 1998-2012), while Burela fleet shows a strong increase mainly since 2005 (Table 1; Figure 1). The Celeiro fleet seems to be stable throughout the time series (around 5000 fd average). The three fleets give similar LPUE means: 0.90 t/fd in the Burela fleet, 0.95 t/fd in the Celeiro fleet, and 0.88 t/fd in the A Coruña fleet. After combining these three fleets, the average LPUE of the recovered period (1995-2012) was 0.93 tons by fishing day (Table 2).  LPUE of hake for the Spanish set-longline fleet operating in ICES Subarea VII shows three different periods in trends (Figure 2): a stable period with an average of 0.81 t/fd throughout the first fourteen years (1995-2008), a three-year period with a marked increase of 66% (2009-2011), and a pronounced decrease (44%) in the last year (2012).   The average of quarterly landing size shows a seasonal increase: 56.3 cm, 57.1 cm, 58.4 cm and 59.8 cm from the first to the fourth quarter, respectively. The annual mean landings size also shows an increase throughout the time series, from 55.4 cm in 1995 to 61.6 cm in 2012 (Figure 3).  DISCUSSION AND CONCLUSIONS The decrease observed in the effort of A Coruña fleet started at the beginning of 90’s, and it is directly related with the start of the longline fishery in Celeiro and Burela ports. This transference of vessels supports the idea to join the three ports in a common LPUE, a well as the similar LPUE mean observed in the three longline series.  It is known the importance of standardization of effort in a longline LPUE, which is strongly dependent of the number of hooks used by trip. Unfortunately, this information has never been collected, so that it is now unrecoverable throughout the time series. However, interviews with skippers describe the Spanish set-longline fishery targeting hake in European western waters as a very homogeneous fishing tactic throughout the period recovered here, without changes due to technological improvements or new management measures. Therefore tons by fishing day can be an optimal candidate of LPUE for this longline fleet. Besides, the practical lack of discards observed in this logline fleet (Pérez et al., 1996) makes reasonable to use landings (LPUE) as proxy of catches (CPUE). 2  WD presented at Benchmark Workshop on Southern Megrim and Hake (WKSOUTH) ICES, Copenhagen, Denmark, 3–7 February 2014 These longliners use an average of 90 hooks per set and 120 sets by haul (Fariña, 2013). Haul fishing starts hauling the lines between 2:00 and 4:00 pm, and begins to be collected in the morning (between 9:00 and 11:00 am). This process continues throughout the day and once completed, a new fishing haul starts. Thus it can be considered that Spanish longliners use around 10000 hooks by fishing day. Sardine, herring or mackerel are used as bait. A trip consists of about 5.3 fishing days in Subarea VII and the most common depth in the trips is located between 250 and 400 m deep. Regarding the obtained LPUE series, the increase observed since 2009 may be related with the high recruitment calculated for 2007 and 2008 (ICES, 2013). Nevertheless, the 3 consecutive years of low recruitment do not seem to produce any decrease on the 2010-1011 LPUEs, which are still increasing. Probably related with this, the increase in the yearly mean size in the last two years of the time series makes to think that older individuals from the 2008 cohort year have been coming into the fishery until 2012, when the LPUE decrease again to the historical mean.  The increase in northern hake SSB observed in the last assessment results is considered the consequence of the 2007-2008 good recruitments as well as the high growth rate estimated by SS3 model (in agreement with the growth rate estimated from tagging data: de Pontual et al., 2009). Though these recent trends are consistent with increasing landings and LPUEs, it is considered that the respective rate of variation may be over-estimated, and the inclusion of tuning information about large fish may help to stabilize the SSB estimates. The time series (1995-2012) of hake LPUE provided here for the Spanish set-longline fleet fishing in ICES Subarea VII is a good candidate to be tested in the WKSOUTH 2014.  References Castro, J., M. Marín, G.J. Pierce, and A. Punzón. 2011. Identification of métiers of the Spanish set-longline fleet operating in non-Spanish European waters. Fisheries Research, 107: 100-111. Fariña, C. 2013. Informe técnico intermedio del proyecto “Estudio sobre el rendimiento y captura por especie en la pesquería española de palangre de fondo en la división VIa del CIEM” (2010/ARM/1281/007). Instituto Español de Oceanografía, 27 pp. ICES. 2013. Report of the Working Group on the Assessment of Southern Shelf Stocks of Hake, Monk and Megrim (WGHMM), 10 - 16 May 2013, ICES Headquarters, Copenhagen. ICES CM 2013/ACOM:11A. 719 pp. Pérez, N., P. Pereda, A. Uriarte, V. Trujillo, I. Olaso y S. Lens. 1996. Descartes de la flota española en el área del ICES. Datos y Resúmenes. Vol 2. NIPO : 251–96–013-X. de Pontual, H., Groison, A.L., Piñeiro, C., Bertignac, M. 2006. Evidence of underestimation of European hake growth in the Bay of Biscay, and its relationship with bias in the agreed method of age estimation. ICES Journal of Marine Science, 63: 1674–1681.      3  WD presented at Benchmark Workshop on Southern Megrim and Hake (WKSOUTH) ICES, Copenhagen, Denmark, 3–7 February 2014  Table 1. Revised series of landings (t), effort (fishing days) and LPUE (t/fd) of the Spanish longline fleet operating in ICES Subarea VII by landing port: Burela, Celeiro and A Coruña.  Landings (t) Effort (fishing days) LPUE (t/fd) Year Burela Celeiro Coruña Burela Celeiro Coruña Burela Celeiro Coruña 1995 2273 5209 2507 2772 6420 2160 0.82 0.81 1.16 1996 3245 5988 2111 3636 6720 1668 0.89 0.89 1.27 1997 2299 4174 830 3540 5040 900 0.65 0.83 0.92 1998 1639 2817 292 3000 5184 372 0.55 0.54 0.78 1999 1982 3447 323 2964 4624 396 0.67 0.75 0.82 2000 2282 3699 281 2928 4440 276 0.78 0.83 1.02 2001 3034 3383 229 3672 3756 276 0.83 0.90 0.83 2002 2399 2841 214 3732 3984 300 0.64 0.71 0.71 2003 2514 3386 192 3612 4404 300 0.70 0.77 0.64 2004 3255 3990 280 3852 4596 312 0.85 0.87 0.90 2005 3074 4177 199 3507 3930 288 0.88 1.06 0.69 2006 3639 4372 256 5184 4572 312 0.70 0.96 0.82 2007 4367 5039 271 5796 5040 340 0.75 1.00 0.80 2008 4058 4302 233 4884 5184 324 0.83 0.83 0.72 2009 5146 4959 214 4536 4624 192 1.13 1.07 1.12 2010 9141 7630 322 5736 5556 375 1.59 1.37 0.86 2011 10908 9672 443 5988 5172 350 1.82 1.87 1.26 2012 7464 6612 218 6984 6720 363 1.07 0.98 0.60 AVERAGE       0.90 0.95 0.88  Table 2. Landings of hake (t), effort (fishing days) and LPUE (t/fd) of the Spanish set-longline fleet which operates in ICES Subarea VII (Burela, Celeiro and A Coruña ports together). Year Landings (tons) Effort (fishing days) LPUE (t/fd) 1995 9988 11352 0.88 1996 11343 12024 0.94 1997 7303 9480 0.77 1998 4748 8556 0.55 1999 5753 7984 0.72 2000 6262 7644 0.82 2001 6647 7704 0.86 2002 5453 8016 0.68 2003 6092 8316 0.73 2004 7526 8760 0.86 2005 7450 7725 0.96 2006 8268 10068 0.82 2007 9676 11176 0.87 2008 8593 10392 0.83 2009 10319 9352 1.10 2010 17092 11667 1.46 2011 21022 11510 1.83 2012 14294 14067 1.02 AVERAGE   0.93  4  WD presented at Benchmark Workshop on Southern Megrim and Hake (WKSOUTH) ICES, Copenhagen, Denmark, 3–7 February 2014 Figure 1. Effort (fishing days) of the Spanish set-longline fleet operating in ICES Subarea VII: by port (Burela, Celeiro and A Coruña) and total (the three ports together).  Figure 2. LPUE (tons/fishing day) time series (1995-2012) of hake for the Spanish set-longline fleet operating in ICES Subarea VII.  Figure 3. Evolution of the hake mean landing size (cm) in the Spanish set-longline fleet operating in ICES Subarea VII.  0 2000 4000 6000 8000 10000 12000 14000 16000 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 Burela Celeiro Coruña TOTAL Spanish set-longline effort (fishing days) in VII 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 NHKE LPUE of the Spanish LLS fleet in ICES Subarea VII 48.050.052.054.056.058.060.062.064.0199519961997199819992000200120022003200420052006200720082009201020112012NHKE mean landings size in Spanish longliners 5  

Compilation of LPUE series of the Spanish set-longline fleet targeting hake in non-Spanish European waters

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