This  paper  presents the  available  information  of  the  Red  seabream  (Pagellus 
bogaraveo)  fishery  in  the  Strait  of  Gibraltar  and  updates  the  documents
presented in previous years  with the information  from the last  analyzed  year,
2012.  The  document  presents  data  about  landings,  LPUE,  length  frequencies 
and  also  some  biological  information  about  the  species  growth  which  should
be useful to fishery management considerations.Versión del edito

Acosta, J.J. (Juan José)

Farias, C. (Carlos)

Gil, J. (Juan)

Soriano, M.M. (María del Mar)

English

This  paper  presents the  available  information  of  the  Red  seabream  (Pagellus 
bogaraveo)  fishery  in  the  Strait  of  Gibraltar  and  updates  the  documents
presented in previous years  with the information  from the last  analyzed  year,
2012.  The  document  presents  data  about  landings,  LPUE,  length  frequencies 
and  also  some  biological  information  about  the  species  growth  which  should
be useful to fishery management considerations

Gil, Juan

Acosta, Juan José

Soriano, María del Mar

Farias, Carlos

Digital.CSIC

The Red seabream fishery in the Strait of Gibraltar: update of the available information from the fishery statistics and some considerations about the current knowledge on the target species growth

Repositorio Institucional Digital del IEO

 1 Working Document presented to the ICES Working Group on the  Biology and Assessment of Deep Sea Fisheries Resources  ICES WGDEEP - Copenhagen 14 - 20 March 2013 This Working Document has not been peer-reviewed by ICES WGDEEP and should not being interpreted as the view of the Group. The Working Document is appended for information only.  The Red seabream fishery in the Strait of Gibraltar: update of the available information from the fishery statistics and some considerations about the current knowledge on the target species growth. Juan Gil, Juan José Acosta, Mª del Mar Soriano and Carlos Farias Centro Oceanográfico de Cádiz  Puerto Pesquero. Muelle de Levante s/n 11006 Cádiz, Spain  Abstract This paper presents the available information of the Red seabream (Pagellus bogaraveo) fishery in the Strait of Gibraltar and updates the documents presented in previous years with the information from the last analyzed year, 2012. The document presents data about landings, LPUE, length frequencies and also some biological information about the species growth which should be useful to fishery management considerations.  1. Introduction and fishery description Since the earlies 1980´s an artisanal fishery targeted to the red seabream (Pagellus bogaraveo, namely “voraz”) have been developing along the Strait of Gibraltar area (ICES IXa south). This fishery has already been broadly described in previous Working Documents presented to the ICES WGDEEP (Gil et al., 2000; Gil & Sobrino, 2001, 2002 and 2004; Gil et al., 2003, 2005, 2006, 2007, 2008, 2009, 2010, 2011 and 2012). Spanish red seabream fishery in the Strait of Gibraltar is almost a monospecific fishery with one clear target species which represents the 74% from the total landed species which constitutes a fleet component by itself (Silva et al., 2002). The Instituto Español de Oceanografía (IEO) began the study and the fishery monitoring following the request from the Fishermen Corporations. In 2006, 2008, 2010 and 2012 different assessment trials were attempted within the ICES WGDEEP (ICES, 2006, 2008, 2010 and 2012). The main objective of this paper is to provide an updated summary of the available fishery information and some considerations about the growth of this deep-water species in ICES area IX to the 2013 ICES WGDEEP meeting.  2 2. Material and methods Fishery information was gathered for the period 1983-2012 from the sale sheets: monthly landings, monthly number of sales and the number of days in which those sales were carried out. Moreover, from the beginning of the IEO monitoring, June 1997, an ad hoc monthly length samplings from the different commercial sizes are carrying out to estimate the landings length distribution (Gil et al., 2000). R software was quite helpful to draw growth curves and integrated recaptures information in it. So observed growth from tag-recapture experiences were compared with the expected ones from three different VBGF estimated by means of otoliths readings results: ALK 1997-1999 (FISHPARM software) and ALK 2003-2009 (FISHPARM software and Bayesian von Bertalanffy growth model with Schnute parameterization). 3. Results and discussion - Landings data: Figure 1 shows a continuous increase of the landings to a maximum in 1994. Since 1994 landings have gone decreasing till 2002, except in 1996 and 1997. Then, from 2003 onwards it shows an increasing trend till reached the highest value of the last years in 2009, followed by a new decrease till last year, with the lowest value of the recent years. However Morocco landings from the same fishing grounds are not included. - LPUEs and CPUEs: Fishing effort increases too till 2009 (Figure 2). It is important to emphasize that the effort unit chosen (number of sales) cannot be too appropriate as do not consider the missing effort. Thus, in the years when the resource is not so abundant the missing effort increases substantially (fishing vessels with no catches, so no sale sheet were recorded). So, the LPUE trend from the decline of the fishery, 1997, should be interpreted with caution because it cannot be a real image of the resource abundance but even so the decreasing trend since 2010 is quite clear. - Length frequencies: The fishery resource suffers a decrease of the landed mean length (Figure 3) mainly from 1995 to 1998. It is necessary to point out that species probably does not have a homogeneous geographic and bathymetric distribution related to their length. This fact could explain the different landed mean length between the main landing ports, Tarifa and Algeciras. The mean length of the landings gets progressively increasing from 1999 onwards, but along the last years the trend varies increasing again from 2006 on in both ports. However the median value from these years remains under the mean in every case. The mean length from both landing  3 ports became lower since 2010. Nowadays there is not minimum landing size adopted for the area. - Biological information: No new biological information is available. Figure 4 draws the size increment between tag and recapture dates from the twelve longest lived samples. In every case observed values are below than the expected in the VBGF functions from otoliths readings. So, it seems that readings may be overestimated and some hyaline rings are uncounted and/or missing. Thus, age and growth based on otolith readings should be revised and further work is needed. 4. Main conclusions Figure 1 is clear enough. There is no evidence of the fishery sustainability at the current levels. Landings and mean length decreasing since 2010 remember a similar history in the middle 1990s. Besides, because of its particular biology the Red seabream may be especially sensitive to overfishing. Fish ageing has an important role in fisheries assessment and management. Typically, fisheries based on slow growing species could be subject to growth overfishing. The use of biased age estimation criterion may have important consequences. Besides, underestimating growth is likely to result also in underestimate of stock´s productivity; a stock with a fast growth rate might recover faster than be expected from low biomass levels, and vice versa. Improving the precision in the absence of accuracy cannot, under any account, guarantee data quality (de Pontual et al., 2006). Therefore, considerable effort should be made to improve the precision of age data through workshops on ageing (i.e. ICES WKAMDEEP next October). Acknowledgments We would like to express our most sincere gratefulness to all those institutions and people for his collaboration in the execution of the present work: - Instituto Español de Oceanografía. - Consejería de Agricultura y Pesca de la Junta de Andalucía. - People from the Fishermen Brotherhood and Fishmarket of Tarifa for their readiness, especially to Juan José Rodríguez-Santander. - The skippers and crews as well all the people who brought their kind collaboration in the tagging and recapture process. - Pascal Lorance for his encouraging and valued comments along the comparison between ALKs and tag-recapture information.  4  5  References DE PONTUAL H., A.I. GROISON, C. PIÑEIRO and M. BERTIGNAC, 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 J Mar Sci 63, 1674-1681. GIL, J., J. J. ACOSTA, C. FARIAS and M.M. SORIANO, 2012. Updating the information about the Red seabream (Pagellus bogaraveo) Spanish fishery in the Strait of Gibraltar (ICES Subarea IX). Work. Doc. to the 2012 Report of the ICES Working Group on the Biology and Assessement of Deep-Sea Fisheries Resources (WGDEEP). GIL, J., J. J. ACOSTA, M.M. SORIANO, C. FARIAS and C. BURGOS, 2011. The Red seabream (Pagellus bogaraveo) fishery in the Strait of Gibraltar: ICES Subarea IX updated data. Work. Doc. to the 2011 Report of the ICES Working Group on the Biology and Assessement of Deep-Sea Fisheries Resources (WGDEEP). GIL, J., J. CANOURA, C. BURGOS and C. FARIAS, 2005. Update of the Red seabream (Pagellus bogaraveo) fishery data in the Strait of Gibraltar (ICES IXa south) including biological information. Work. Doc. to the 2005 Report of the ICES Working Group on the Biology and Assessement of Deep-Sea Fisheries Resources (WGDEEP). GIL, J., J. CANOURA, C. BURGOS and C. FARIAS, 2010. The Red seabream (Pagellus bogaraveo) Spanish fishery in the Strait of Gibraltar: Useful information that should be considered for the ICES Subarea IX assessment update exercise. Work. Doc. to the 2010 Report of the ICES Working Group on the Biology and Assessement of Deep-Sea Fisheries Resources (WGDEEP). GIL, J., J. CANOURA, C. BURGOS, C. FARIAS and V. POLONIO, 2008. Red seabream (Pagellus bogaraveo) assessment of the ICES IX from the information available of the fishery in the Gibraltar Strait. Work. Doc. to the 2008 Report of the ICES Working Group on the Biology and Assessement of Deep-Sea Fisheries Resources (WGDEEP). GIL, J., J. CANOURA, C. BURGOS and I. SOBRINO, 2007. Red seabream (Pagellus bogaraveo) fishery of the Strait of Gibraltar (ICES IXa south): Update of the available information. Work. Doc. to the 2007 Report of the ICES Working Group on the Biology and Assessement of Deep-Sea Fisheries Resources (WGDEEP).  6 GIL, J., I. SOBRINO and M. P. JIMÉNEZ, 2000. A brief description of the Strait of Gibraltar red seabream (Pagellus bogaraveo) fishery. Working Document to the 2000 Report of the ICES S.G. on the Biology and Assessmnet of Deep-sea Fisheries Resources (SGDEEP). GIL, J. and I. SOBRINO, 2001. New biological information about the red seabream (Pagellus bogaraveo) of the Strait of Gibraltar (ICES IXa). Work. Doc. to the 2001 Report of the ICES Working Group on the Biology and Assessement of Deep-Sea Fisheries Resources (WGDEEP). GIL, J. and I. SOBRINO, 2002. Update of the information about the red seabream (Pagellus bogaraveo) from the Strait of Gibraltar (ICES IXa south). Work. Doc. to the 2002 Report of the ICES Working Group on the Biology and Assessement of Deep-Sea Fisheries Resources (WGDEEP). GIL, J. and I. SOBRINO, 2004. Red seabream (Pagellus bogaraveo) fishery of the Strait of Gibraltar (ICES IXa south): Update of the information available. Work. Doc. to the 2004 Report of the ICES Working Group on the Biology and Assessement of Deep-Sea Fisheries Resources (WGDEEP). GIL, J., I.SOBRINO and J. CANOURA, 2003. Update of the information about the red seabream (Pagellus bogaraveo) fishery in the Strait of Gibraltar (ICES IXa south). Work. Doc. to the 2003 Report of the ICES Working Group on the Biology and Assessment of Deep-Sea Fisheries Resources (WGDEEP). ICES, 2006. Report of the Working Group on the Biology and Assessment of Deep-sea Fisheries Resources. ICES CM 2006/ACFM: 28. ICES, 2008. Report of the Working Group on the Biology and Assessment of Deep-sea Fisheries Resources. ICES CM 2008/ACOM: 14. ICES, 2010. Report of the Working Group on the Biology and Assessment of Deep-sea Fisheries Resources. ICES CM 2010/ACOM: 17. ICES, 2012. Report of the Working Group on the Biology and Assessment of Deep-sea Fisheries Resources. ICES CM 2012/ACOM: 17. SILVA, L., J. GIL and I. SOBRINO, 2002. Definition of fleet components in the Spanish artisanal fisheries of the Gulf of Cádiz (SW Spain, ICES Division IXa). Fisheries Research 59 (2002):117-128.  7   0100200300400500600700800900198319841985198619871988198919901991199219931994199519961997199819992000200120022003200420052006200720082009201020112012Tons Figure 1. Red seabream Spanish fishery of the Strait of Gibraltar: Landings (1983-2012).    020406080100120020004000600080001000012000LPUEFishing effort (Nº sales)Nº sales LPUE Figure 2. Red seabream Spanish fishery of the Strait of Gibraltar: Evolution of the chosen effort unit (number of sales) and its estimated LPUE (1983-2012).  8    Figure 3. Red seabream Spanish fishery of the Strait of Gibraltar: Evolution of the landings length distribution descriptive statistics.    Figure 4. Red seabream of the Strait of Gibraltar: von Bertalanfy growth curves estimated from otolith readings. Straight lines correspond to the 12 long time at sea recaptures (Left: ALK 1997-1999; Center: ALK 2003-2009 FISHPARM soft. and Rigth: ALK 2003-2009 Bayesian fit). TOTAL TARIFA ALGECIRAS 

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The Red seabream fishery in the Strait of Gibraltar: update of the available information from the fishery statistics and some considerations about the current knowledge on the target species growth

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