Current Knowledge on Sardine and Hake Exploitation and Status in the Alboran Sea, and the Question of Stock Units Identification

23 OCCASIONAL PAPER Current knowledge on Sardine and Hake exploitation and status in the Alboran Sea, and the question of stock units identification. Author: Henri Farrugio. CopeMed Consultant Current knowledge on Sardine and Hake exploitation and status in the Alboran Sea, and the question of stock units identification. Author: Henri Farrugio. CopeMed Consultant Document prepared as a contribution to the CopeMed II Workshop on methodologies for the identification of stock units in the Alboran Sea. Alicante, Spain, 3-6 April 2017 Introduction Many marine living resources may potentially be considered as shared resources in the Alboran Sea. Sardine and hake are important species exploited in the area by Algerian, Moroccan and Spanish fleets. They belong to the list of “priority species” of the General Fisheries Commission for the Mediterranean and from a management point of view they have been considered as belonging to 4 independent stocks: the northern one, corresponding to the GFCM Geographical Sub-Area 01 (GSA 01: waters off the Spanish coast), the southern one corresponding to the GFCM/GSA 03 (waters off the Moroccan coast), the waters surrounding the island of Alboran (GFCM/GSA 02) and the western part of the GFCM/GSA 04 (Algerian coast). Fig.1- Limits of the four GFCM Geographical sub areas in the Alboran sea. Originally the delimitation of the geographical sub-areas (Fig.1) was essentially based on political and statistical considerations without considering the biological structuring of the animal populations. The GFCM glossary define a fish stock as “the part of a fish population which is under consideration from the point of view of actual or potential utilization”. This definition is similar to that of “harvest stock” of Coyle (1998); The term ‘‘stock’’ does not automatically imply genetic differentiation but it implies that the concerned group of fish exploited in a specific area is more or less isolated from the other ones of the same species and thus self-sufficient, and that the abundance of this group depends more on recruitment and natural and fishing mortality within the area than on immigration and emigration. Workshop on methodologies for the identification of stock units in the Alboran Sea April 2017, Alicante, Spain ϭ The fish populations or subpopulations do not adhere to the political boundaries./Ĩwe except few attempts to assess some species distributed across adjacent GSA’s, many Mediterranean resources are still currently managed without regard to their true biological structuring. Generally the degree of overlap between the current harvest stocks is unknown. As a consequence the stock units can be considered as not well defined and this situation could have an impact on the stock assessment results and also precludes effective harvest regulation The biological processes (growth, recruitment, mortality) are traditionally regarded as the significant factors determining the fish population dynamics, but in many cases there is a lack of knowledge on the real geographical distribution of the species, their spawning areas and migrations. 1. Review of the current knowledge on sardine and hake in the Alboran sea The different fleets targeting sardine and hake in the Alboran Sea exhibit different exploitation patterns and differences have been observed in the biological parameters and size distributions of these species in the various GSA’s of this sea. Under the hypothesis of independent northern and southern stocks several assessments have been performed during the last years for the two species. Furthermore, although there are still many doubts about the possibility of single shared sardine and hake stocks, three assessments have also been performed under this hypothesis. The following information regarding these studies has been extracted mainly from the various assessment forms, reports of the small pelagics and demersals working groups, reports of the subcommittees of the GFCM and from the technical documents of the COPEMED project available on their internet websites (see references section). 1.1. Sardine 1.1.1.Sardine in the Northern Alboran sea (GSA 01 ) In the northern Alboran Sea the main density of sardine is detected near the Spanish coast between Malaga and Almeria (fig. 2) Fig.2- Distribution of sardine in the northern Alboran sea (Spanish ECOMED and MEDIAS echosurveys). The Spanish purse seine fleet targeting the small pelagic species (mainly sardine and anchovy) in the GSA 01, the so called “flota surmediterranea” (RSM), has been continuously decreasing in the last two decades, from more than 230 vessels in 1980 to 94 in 2008 and to 87 in 2015 (tab.1) Ϯ A strong reduction of larger vessels occurred from 1985 onwards, possibly linked to a decreasing in anchovy catches in Northern Morocco, where a part of that fleet fished under agreement between the two countries. Subsequently the fleet continued to decline but more slowly. In 2016 the Spanish fleet in GSA 01 was composed by 87 units, characterized by small vessels, average TJB 24.7. 16% of them smaller than 12 m, and no one bigger than 24m. A great decrease in the number of smaller units has occurred from 2000 to 2015 (fig.3). Traditionally, the most important ports in number of units and landings have been Almería, Adra and Málaga. ǇĞĂƌ ϮϬϬϬ ϮϬϬϭ ϮϬϬϮ ϮϬϬϯ ϮϬϬϰ ϮϬϬϱ ϮϬϬϲ ϮϬϬϳ ϮϬϬϴ ϮϬϬϵ ϮϬϭϬ ϮϬϭϭ ϮϬϭϮ ϮϬϭϯ ϮϬϭϰ ϮϬϭϱ ŶďďŽĂƚƐ ϭϴϳ ϭϴϰ ϭϲϴ ϭϲϳ ϭϲϬ ϭϰϵ ϭϯϱ ϭϯϲ ϭϯϲ ϭϭϯ ͙ ͙ ϵϭ ͙ ϴϴ ϴϳ Tab.1- The Sardine Spanish fleet GSA 01 Fig.3- composition of the Spanish purse seine for small pelagic fleet in GSA 01 in 2000 and 2015 Although sardine has a lower price than anchovy, it is an important support to the small pelagics Spanish fishery as it is the most fished species. Catches in the period 1990-2015 has been highly variable, with a minimum of 3000 tons in 1997. Highest catches occurred in 1992 (11000 tons). All period average is about 6000 tons. During the period the CPUE values of the Spanish fleet have followed very similar variations (fig.4, tab.2). ϯ Fig.4- Trends in sardine landings and CPUE in South Mediterranean Region 1990-2015. CPUE CPUE Catch (tons Catch YEAR Kg/fishing day YEAR Catch (tons) Kg/fishing day GSA01 (tons) 1990 6439 921 2003 7472 1292 8087 1991 9599 1328 2004 3793 851 3957 1992 10826 1308 2005 6773 1302 7516 1993 5782 1095 2006 8846 1505 9971 1994 5220 926 2007 5443 1252 6139 1995 4316 756 2008 4339 1070 4468 1996 3589 612 2009 5896 1347 5972 1997 3263 726 2010 7164 1306 7328 1998 3982 839 2011 6065 1170 6293 1999 5146 1143 2012 5431 1129 6214 2000 8697 1369 2013 4456 978 4983 2001 6817 1255 2014 4782 952 5174 2002 5055 1010 2015 5058 977 5248 Average 1990- 6001 1074 6187 2015 ϰ Tab. 2- Spanish cCatches used in the assessment 1990-2015. The landings correspond to the Southern Mediterranean Region (around 95% of the catches in GSA01). In GSA 01 the sardine catches are composed mainly by young individuals from the 0 to 2 age groups (tab.3, fig. 5) Tab.3- Age composition of the sardine catches in GSA 01 Fig.5-.A: Length distribution sardine fishery 2002-2015 and B: 2014-2015 by ports 1.1.2.Sardine in the Southern Alboran sea (GSA 03) Sardine is present all along the Moroccan coast from Ceuta border to Saidia (fig.6). dŚĞŵĂŝŶ ĐŽŶĐĞŶƚƌĂƚŝŽŶƐ ĂƌĞ ŽďƐĞƌǀĞĚ ŽŶ ďŽƚŚ ƐŝĚĞƐ ŽĨ ĂƉĞ dŚƌĞĞ &ŽƌŬƐ ĂŶĚ ŶĞĂƌ ĂƉĞ ^ŝĚŝ ďĞĚ͕ ŝŶ ƚŚĞ ƌĞŐŝŽŶŽĨů,ŽĐĞŝŵĂ͘ Fig.6- Distribution of sardine in the southern Alboran sea (Moroccan trawl surveys) The Moroccan purse seiners fleet active in 2015 in GSA 03 was composed by 113 units, characterized by small vessels (average TJB=50 and 250 horse power). 7% of them are smaller than 12 m, 86% of them are between 12 m and 24 m, and 7% are bigger than 24m. In addition there are around one hundred small scale boats fishing in the coastal areas ϱ This fleet is based mainly in 4 important ports M'diq, Nador, Al Hoceima and Ras Kebdana with high mobility between ports and a high annual variability in the number of active vessels (tab. 4) due to changes in fishing grounds (Mediterranean or Atlantic) and the fishing effort of the Moroccan fleet is variable from one year to another according to climatic conditions and abundance of the resource, generating variable values of catch per unit effort (CPUE). ǇĞĂƌ ϮϬϬϯ ϮϬϬϰ ϮϬϬϱ ϮϬϬϲ ϮϬϬϳ ϮϬϬϴ ϮϬϬϵ ϮϬϭϬ ϮϬϭϭ ϮϬϭϮ ϮϬϭϯ ϮϬϭϰ ϮϬϭϱ ŶďďŽĂƚƐ ϭϯϵ ϵϮ ϭϭϯ ϭϯϰ ϭϰϳ ϭϯϳ ϭϰϭ ϭϰϰ ͙ ϭϭϲ ͙ ͙ ϭϭϯ Tab. 4- The Moroccan Sardine fleet in GSA 03 The landings of sardine in the Moroccan Mediterranean Sea are of primary importance compared to other species. Between the years 2005 and 2015 the annual production of sardines of the Moroccan fleet fluctuated between 7000 and 15300 tons/year. with an average annual production of 12000 tonnes. Exploitation of sardine is practiced essentially by purse seiners. Catch per unit effort CPUE generally varies between 890 and 2090 kg/day with an average of 1360 kg/day (tab.5 and fig.7 and 8) YEAR Catch CPUE YEAR Catch CPUE ϮϬϬϬ ϭϴϵϮϴ ϮϬϬϴ ϲϯϲϴ ϭϲϱϵ ϮϬϬϭ ϭϵϭϵϲ ϮϬϬϵ ϭϯϳϵϰ ϭϰϴϳ ϮϬϬϮ ϭϮϱϯϳ ϮϬϭϬ ϭϬϳϰϰ ϭϮϯϴ ϮϬϬϯ ϭϬϲϳϮ ϭϱϱϴ ϮϬϭϭ ϱϳϱϯ ϭϬϭϰ ϮϬϬϰ ϭϮϰϱϴ ϯϳϮϴ ϮϬϭϮ ϴϭϮϭ ϭϯϮϭ ϮϬϬϱ ϵϮϮϴ ϮϬϭϲ ϮϬϭϯ ϭϮϲϭϯ ϭϯϯϰ ϮϬϬϲ ϱϬϮϰ ϴϴϴ ϮϬϭϰ ϭϯϮϴϲ ϭϭϲϰ ϮϬϬϳ ϭϬϵϮϬ ϭϬϴϲ ϮϬϭϱ ϭϭϬϮϵ ϭϭϬϱ Tab.5- Moroccan Catches (tons) and CPUE (kg/fishing day) in the GSA 03 Fig. 7- Sardine Moroccan landings from 1970 to 2014 ϲ Fig. 8- Recent trends in sardine Moroccan landings and CPUEs The sardine caught in the eastern part of the Moroccan Alboran Sea (Nador - Ras Kebdana) are juveniles (40% of the catch) while in the western part of the coast (Al Hoceima) the catch is mainly composed by adults between 16.5 and 19.5 cm.

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