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).

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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.

Fig.9-Length frequencies distributions of the sardine caught in GS 03 by the Moroccan fleet An Algerian fleet targeting sardine and anchovy and other small pelagic species is operating in a small part of GSA 04 situated near the Moroccan border. Fishing gears targeting small pelagic are essentially purse seine and pelagic trawl from the early 90s. In 2012, the Algerian fleet was composed of small purse seiners (6-12 m) and 119 large purse seiners (12-24m). The sardine was also targeted by a fleet of 38 small pelagic trawlers (12-24 m) and 7 large ones (>24m). The main Algerian landing ports are Ghazaouet, Béni-Saf and Bouzedjar. Algeria accounts for a high proportion of the total catches of sardine in the Alboran Sea (tab.6) dƌĂǁů W͘^ĞŝŶĞ ^ŵĂůůƐĐĂůĞ dŽƚĂů

>'Z/ ϯϭϲϲ ϮϴϮϲϮ ϵϭϱ ϯϮϯϰϮ

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ϳ ^W/E ϲϮϮϬ ϲϮϮϬ

dŽƚĂů ϰϲϳϲϴ

Table 6. Average (2010 – 2012) catches of sardine by country fishery types 1.1.3. Sardine stock assessments

Up to now the sardine resources of the Alboran Sea have been assessed considering that each GSA was housing an independent stock. Three assessments considering a possible single shared sardine stock in the Alboran Sea have been done in 2012, 2015 and 2016, but there are still many doubts about this hypothesis. For GSA 01 the last assessment has been done in 2015 by applying the XSA model (Extended Survivor Analysis) to Catch-at-Age data calculated from landings and length distributions series for the period 2003-2015. The model was tuned using the data from MEDIAS acoustic surveys in 2012-2015 and the commercial tuning fleet (2003-2015). The results (fig.10) have shown a Recruitment quite stable with some peaks in 2003 and 2011. The trends of Biomass and Spawning Stock Biomass are stable since 2013. Biomass is at an intermediate level. Furthermore, the ratio Fcur/F0.1 = 1.26 so the fishing effort was considered as high and the sardine stock in GSA01 being in overexploitation.

Fig.10- Main results obtained for the sardine stock in GSA 01 by XSA model in 2015 The BioDyn non-equilibrium Surplus production Model based on the Schaefer (logistic) population growth model was also used and its results were consistent with the trends observed in the landings. The exploitation rate was E= 0.52 which is higher than the standard Patterson value of 0.4, so this stock have been considered as overexploited. As FCur/F0.1=1.06 was lower than 1.33 level it was considered low overfishing.

MSY BMSY FMSY F0.1 FCur BCur/BMS Fcur/FSYCur Fcur/FMSY Y 7048 12499 0.56 0.51 0.6 0.65 0.79 1.06

Tab. 7. Reference points calculated by the BioDyn model

ϴ The BioDyn model allow the optional incorporation of an environmental index. It was used previously on the GSA 01 sardine assessment in 2015 testing two different environmental indexes: average chlorophyll-a concentration over the continental shelf and North Atlantic Oscillation (NAO); neither of them showed any improvement in the model fit.

Other tests were also done with the model CMSY to estimate reference points (MSY, Fmsy, Bmsy) as well as relative stock size (B/Bmsy) and exploitation (F/Fmsy) from catches data and acoustic estimates. In the table below, results between two methods are compared.

D^z D^z ZĞĨĞƌĞŶĐĞƉŽŝŶƚƐ ŝŽǇŶ ^ĐŚĂĞĨĨĞƌ ďĂǇĞƐŝĂŶ ĐƵƌͬŵƐǇ Ϭ͘ϲϱ Ϭ͘ϲϬ Ϭ͘ϴϱ &Ƶƌͬ&Ϭ͘ϭ ϭ͘ϭϴ zĞĂƌƐ ϭϵϵϲͲϮϬϭϰ ϭϵϱϳͲϮϬϭϰ ϭϵϵϬͲϮϬϭϰ

For GSA 03 the last assessment of sardine stock has been done in 2014 applying the BioDyn model and a VPA Extended Survivor Analysis (XSA) on a landings time series 2005-2014. $FFRUGLQJWRWKH*)&0IUDPHZRUNIRUDGYLFHWKHUHVXOWVRIWKH%LR'\QPRGHO KDYHVKRZQWKDWWKLVVWRFNZDVRYHUH[SORLWHGZLWKORZILVKLQJPRUWDOLW\7KH UHVXOWVRIWKH9,7PRGHOKDYHVKRZQDQH[SORLWDWLRQUDWHabove the threshold of 0.4 suggested as a biological reference point for small pelagics,LQGLFDWLQJWKDWWKLVVWRFN ZDVRYHUH[SORLWHG.

For GSA04 in 2015 data on catches from the three Algerian ports in the Alborán area (Ghazaouet, Beni-Saf and Bouzedjar) from 1983 to 2014 were pooled together with Spanish and Moroccan catches for a joint run with CMSY. The results were very similar. Algerian catch data from 1970 to 2014 from the same three ports in the Alboran area were also used for a run with CMSY independently of the other two GSAs. The outcomes of this model, although to be considered as an exploratory test, showed that sardine in Algeria could be under overexploitation with a low level of biomass (fig.11).

Fig.11- results of the CMSY model applied to the Algerian sardine catch data in GSA 04

ϵ Although there is no information on sardine migration in the Alboran Sea, it can be expected that the Atlantic surface current and the main oceanographic events (anti-cyclonic and cyclonic gyres) may lead to a relationship may exist between larvae and eggs distribution in the northern and southern areas. Under a single shared stock hypothesis there have been three joint assessments between Spain and Morocco combining GSA 01 and GSA 03 sponsored by Copemed II in 2012, 2015 and 2016. All of them have been submitted to the GFCM Working Group of assessment of small pelagics In 2015 these assessments were done using catches and CPUEs from the commercial fishery 1990–2014 and direct acoustic estimates for the period 2005–2014. The Biodyn model was applied on total yearly catch (tons Morocco plus Spain) and using as an abundance index the biomass assessed by Moroccan acoustic survey over the period 2005- 2014. The results based on Biodyn model are consistent with trends observed in the landings. The fishery would be, according to the GFCM framework for advice, overexploited with low fishing mortality. The sardine stock in the area was also assessed using a VPA model based on VIT software applied on catch numbers structured by age for five years, (number by age of Morocco and Spain combined). The ratio Fcur/F0.1 is quite similar in both cases and lower than 1, indicating low fishing mortality. The trend in biomass since 2011 is increasing, with a remarkable peak in 2014, what is also consistent with the biomass level estimated by Biodyn, 98% of BMSY (tab.8).

VIT BioDyn F0.1 0.67 0.98 Fcur 0.46 0.64 FCur/F0.1 0.68 0.65 E 0.48 0.68

Tab.8- Comparison table between BioDyn and VIT results.

This assessment has been considered as uncertain due to the strong influence of high biomass in GSA03 that drives the whole assessment towards its own dynamics. Questions on whether the two GSA should be considered as a single stock still remain. Two assessments performed separately to both GSAs produced contradictory results and no management advice can be derived from this assessment which results are uncertain.

In 2016 no information on the delimitation of the sardine stock was provided to enable to decide whether it should be considered as a shared stock, however a new joint assessment has been done applying a VPA Extended Survivor Analysis (XSA) on Spanish and Moroccan time series of landings for the period 2010-2015 tuned with abundance indices from the 2012 to 2015 data of the ACOUMED Moroccan survey at sea and the Spanish MEDIAS survey, the two surveys being summed up to obtain a total biomass estimate in the area. TheXSA results (fig.12) show that Recruitment is different from one year to another with peak in 2013 and 2015. Average fishing mortality in ages 1-2, has the same trend like recruitment. It fluctuates between 0.3 and 1. Biomass and Spawning Stock Biomass show decreasing trends since 2010. Reference points obtained are included in table 9

ϭϬ Fig.12- Main results obtained by XSA model for the GSA01+GSA03 shared sardine stock hypothesis.

Tab. 9- Reference points for fishing mortality (F) and Patterson exploitation rate (E) in the combined assessment (GSA01 and GSA03)

The exploitation rate is above the threshold of 0.4 usually suggested as a biological reference point for small pelagics, but F current is below F0.1 therefore, according to GFCM framework for describing stock status and providing management advice in relation to reference points, sardine stock in GSA combined 01 and 03 the Working Group on Stock Assessment of Small pelagics species of GFCM decided to consider this stock (combined GSA01+GSA03) sustainably exploited. However, there is still a need to promote new scientific studies to determine if this is a shared stock.

Two other separate assessments were done for GSA01 and GSA03 independently using XSA. The results in table 8 showed different exploitations status highlighting once again the need for determination of stock identities.

Reference Points XSA GSA 01 GSA 03 F0.1 0.23 0.86 Fcur (Fbar 1-2) 0.29 0.61 F/F0.1 1.26 0.71 E ?? 0.47 Tab. 8- Reference points for fishing mortality (F) and Patterson exploitation rate (E) in the separate assessments for the two GSAs

According to these last results, the Working Group on Stock Assessment of small pelagic species (WGSASP) stated the following recommendations as gathered in the report:

ϭϭ “The WG stressed that the issue of stock boundaries was still problematic for many stocks and the relevance of joint assessments versus separate assessments needed to be further studied. In particular, in the Alboran Sea, the WG asked for an in-depth analysis on stock boundaries and the pertinence of joining GSAs 1 and 3 for sardine. Indeed, the joint assessment relied almost exclusively on GSA 3 catches where most of the biomass was located. In addition, the perspective of the stock status in GSA 1 was different from the one in the joint assessment, potentially reflecting regional differences. The WG was not in a position to determine which was the most valid management unit. It therefore provided advice for both management units (i.e. separated GSA 1 and GSA 3, and combined GSAs 1 and 3), as the three assessment models were considered technically valid. This issue should be further investigated in the Subregional Committee of the Western Mediterranean and the SAC. Moreover, a workshop should be held by CopeMed II in 2017 to define a work plan in order to identify stock boundaries.”

1.2. Hake The European hake (Merluccius merluccius) is usually found between 70 and 370 m depth, but may also occur within a wider depth range, from inshore waters (30 m) to 1 000 m (fig.13). It lives close to the bottom during day-time, but moves off- bottom at night. The spawning period is very long and lasts from December to June in the Mediterranean. Spawning occurs between 100 and 300 m depth. Up to age 3, juveniles live on muddy bottoms, moving toward the coast at age 3. Males mature at 26-27 cm, females at 36-40 cm. Females grow faster than males. The fecundity is reported as 2 to 7 million eggs per female. Adults feed mainly on fish and squids. The young feed on crustaceans (especially euphausiids and amphipods).

Fig.13- Trawl surveys hake spatial distribution of estimated abundances in 2015

1.2.1. Hake in the northern Alboran Sea (GSA 01) In GSA 01 Hake is one of the main species targeted mainly by Spanish trawlers (91% of the landings on average) on the shelf and slope, and by small-scale fisheries using gillnets (6% of the landings) and long lines (3% of the landings) on the shelf (average percents estimated between 2012 and 2015). In 2014 the Spanish trawling fleet in the GSA01 area was made up of 183 boats, averaging 35 GRT and 176 HP. The port of Almeria had the largest number of boats with an average of 40 units. In 2015 the Spanish trawler fleet was composed of 124 boats.

ϭϮ Recruitment of hake is present along the whole year along the northern coast of GSA 01 with variable recruitment peaks in spring and autumn, probably depending on oceanographic conditions.

The species is exploited in all trawlable areas from Gibraltar straight to Cape of Gata, including the deep-bottom fishing grounds around Alboran island (fig.14). The Spanish catches are made up mostly of young individuals, distributed in a wide bathymetric range from 30 m to 300 m, occupying the whole shelf and upper slope whereas adults reach the maximum depths exploited, 800 m, associated with the shrimps Parapenaeus longirostris and Aristeus antennatus and with the Norway lobster Nephrops norvegicus.

Fig. 14- Trawlable areas exploited by the Spanish fleet targeting the hake

The total annual catches by the Spanish fleet (tab. 10 and fig.15) oscillated around an average value of 417 tons for the period 2003-2014 (275 tons in 2014) with a maximum value in 2004, followed by a stabilization of the yearly catches around 300 tons during the period 2005-2008. Catches increased from 2009 to 2011 reaching 635 tons (the highest in the series) and decreasing again to 295 tons in 2015.

Year 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 Catch (t) 427.8 519.8 313.2 291.9 298.9 294.8 584.4 544.8 653.5 458 347.2 275.1 295

Tab. 10- GSA 01 hake Spanish fleet catch statistics

ϭϯ Fig. 15- Landings by fishing gear in GSA 01

Landings were largely composed of age 0 immature individuals from 2003 to 2008. However, this pattern changed from age 0 to age 1 from 2009 onwards.

GSA 02: There is not a Spanish fishery targeting M. merluccius in GSA 02. (Annual landings from GSA 02 represent about 1% of the total Spanish landings).

1.2.2. Hake in the southern Alboran Sea: In the GSA 03 the European hake is also one of the most important demersal target species of the commercial fisheries. In this area, the species is exploited mainly by the Moroccan coastal trawlers most of them based in the ports of Nador, Al Hoceima and M’Diq. In 2014 around 115 boats 16 to 20 meters long have been involved in this fishery, with a range of 28 to 55 GRT and 200 to 357 HP. In 2015 the number of trawlers targeting M. merluccius in GSA 03 was 71 with an average engine power of 230 HP and a mean GRT of 50 Tx (tab. 11). Long liners are not found in Moroccan GSA 03.

Tab. 11. Segment characteristics for the Moroccan fleet operating in GSA 03 The catch of the Moroccan trawlers fleet is highly multispecific, composed essentially by the deep water pink shrimp (Parapenaeus longirostris), the common octopus (Octopus vulgaris), the axillary sea-bream (Pagellus acarne), the bogue (Boops boops), the red mullet (Mullus barbatus), the striped mullet (Mullus surmuletus), the European conger (Conger conger) and others fishes, crustaceans and cephalopods species. Landings are made at 4 fishing ports: Beni Nsar (Nador), Al Hoceima, M’diq and Tangier. The port of Nador is the most important in terms of hake (90%) and with regard to the fishing effort (89%). For the period 2003-2015, the mean annual hake production of the Moroccan fleet was 105 tons (fig.16) with a high peak in 2006 (547 tons) corresponding to a very high recruitment which has been detected at that time. In 2015, the hake production represented 0,45 % (105 tons) of the total production of the demersal fishery.

ϭϰ Fig. 16- Hake Moroccan landings and CPUE’s in the GSA 03 from 2003 to 2015

In the GSA 04 M. merluccius is found from 20 to 800 m showing the maximum abundance in the stratum 51-100. The length frequency distributions from the ALDEM trawl survey of demersal resources of the Algerian coast (CNRDPA / MPRH) in 2012 and the M. merluccius production (2006-2010) in GSA 04 are shown in figures 17and 18. Catch and effort data are provided from the Algerian ministry of fishing and fisheries resources (MPRH).

The Algerian production showed a global increasing trend from 2006 to 2010. In 2010, the hake production by trawl was 270 t, and 18 t were landed by the artisanal fleet (fig.17).

Fig. 17- Algerian Hake production (tons) in GSA 04 (2006-2010).

Fig. 18- Hake length frequencies in GSA 04 (trawl survey ALDEM 2012). 1.2.3. Hake stock assessments:

ϭϱ Under the assumption of a single GSA01 hake stock, a VPA Extended Survivor Analysis (XSA) tuned with CPUE from commercial fleet and abundance indices from MEDITS trawl surveys (fig. 19) was carried out in 2014 on a 2003-2014 data set, as well as a Sensitivity and retrospective analysis and a yield per recruit analysis. The results of this analysis showed a decreasing trend in the two last years of the series both in recruits number and spawning biomass. Fishing mortality decreased in the last year but still remained high.

Fig. 19- Trends in abundance indices (n/km2) and biomass indices (Kg/day) calculated from MEDITS-ES trawl surveys 1995-2013 for the hake in the Alboran Sea..

A Yield per recruit analysis was performed, based on the exploitation pattern resulting from the XSA model and population parameters. Y/R analysis has shown that the current fishing mortality (1.4) exceeds 7 times the F0.1 reference point (0.2) (fig.20). The resource was considered in overexploitation status and a reduction of the current fishing mortality was recommended by reducing the fishing effort and improving the selection pattern of the fishery

Fig. 20- GSA 01 : Hake Yield per Recruit and SSB curves

ϭϲ Under the assumption of a GSA03 hake stock, a Schaeffer production model has been built In 2014 using data from the Moroccan trawl fishery on a 2003–2013 data set (annual landings of Merluccius merluccius and abundance indices coming from trawl surveys). The results indicated that the status of such a stock was in sustainable exploitation with relative high biomass. However, given the extremely high value calculated for FMSY, the status and advice were therefore considered preliminary and not validated for management advice.

The available scientific literature on the European hake sometimes indicate that the Atlantic and Mediterranean hake populations clearly have different genotypes (Roldan et al., 1998) different otholith composition (Swan et al., 2006) or on the contrary that they cannot be reliably identified from each other and that subdivisions may exist on each population (Pita et al., 2013), Anyway there are still no evidence of genetic differences nor information on hake migration between the northern and southern parts of the Alboran Sea. However, as stated in the sardine section it can be expected that the Atlantic surface current and the main oceanographic events may lead to the possible existence of certain connectivity between larvae and eggs distribution in the northern and southern areas. Under the CopeMed II project a preliminary international stock assessment was done in 2013, aggregating data from GSA01, 02, 03 and 04, considering that they could host a single stock of hake. This assessment was presented and discussed during the 2014 session of the Sub Committee on Stock Assessment of the GFCM-SAC. No advice was given and it was recommended to investigate suitable techniques to improve the knowledge on stock unit. A more recent joint assessment has been carried out in November 2016 using catch time series 2007-2015 (official landings and discard data) from the Spanish and Moroccan trawl fleets and the length distributions 2007-2015 (monthly onboard and port sampling). Along the period of the data series landings have shown important oscillations. However, in the last five years from 2011 onwards, a regular decreasing trend in landings and CPUE’s is observed (fig.21).

ϭϳ Fig. 21- Hake 2003-2015 (trawl fleet) : landings and Catch per unit of effort (kg/fishing days) historical trends The assessment was performed using the XSA Lowestoft VPA software and the open-source framework FLR. The analysis was tuned using the data from the Spanish MEDITS surveys and commercial fleet 2007-2015 and from the Moroccan Mediterranean survey 2010-2015 (fig.22)

Fig.22- Length frequencies and Trends in abundance indices of hake (in kg/km2 for GSA 01 and in kg/hour for GSA 03).

(It has to be kept in mind that the the standardization of the indices produced by the Spanish and the Moroccan surveys as not yet been done, so the differences between the trends in abundance obtained using the Spanish and Moroccan survey indices cannot currently be considered as an evidence of separate units) XSA results showed that the Spawning biomass (SSB) and the yield have followed a decreasing trend from 2011 to 2015. Fishing mortality showed a decrease from 2012 to 2015 while recruitment showed fluctuations over the all series, increasing in the last year (fig.23).

ϭϴ Fig. 23- Main results obtained by XSA model for the GSA01+GSA03 shared hake stock hypothesis A Yield per recruit analysis was conducted based on the exploitation pattern resulting from the XSA model and population parameters (fig. 24).

Fig. 24- Yield per recruit curve for the shared GSA 01 + 03 hake stock hypothesis.

This stock has been retained as being in a very severe status of overexploitation with a current F nearly 10 times higher than the reference point F0.1 and low values for the biomass and spawing stock biomass.

2. Review of available parameters and assessments results.

ϭϵ

Tab. 12- Biological parameters used for the various stock assessments of sardine and corresponding methods of analysis and diagnosis (synthesis from the GFCM and COPEMED documents). FullyExp = fully exploited, OverExp = overexploited, Sustainab = sustainable exploitation.

'^Ϭϯ :ŽŝŶƚƐƐĞƐƐŵĞŶƚ ^Z/E ϮϬϬϮ ϮϬϭϭ ϮϬϭϯ ϮϬϭϰ '^ϬϭϮϬϭϱ '^ϬϯϮϬϭϱ DĂǆ͘ƐŝǌĞ ϮϮ͕ϱ Ϯϭ ϮϬ͕ϱ Ϯϯ͕ϲ ϮϬ͕Ϯ ϭƐƚŵĂƚƵƌŝƚǇ ϭϯ͕ϯ ϭϯ͕ϯ ϭϯ͕ϲ ϭϯ͕ϱ ϭϮ ϭϯ͕ϲ ZĞĐƌƵŝƚ͘ƐŝǌĞ ϭϭ͕ϱ >ь Ϯϭ͕ϯ Ϯϭ͕ϯ Ϯϭ͕ϯ ϮϬ͕ϵ ϮϮ͕ϯ < Ϭ͕ϱϲ Ϭ͕ϱϲ Ϭ͕ϱϲ Ϭ͕ϱϳ Ϭ͕ϰϳ ƚϬ ͲϬ͕ϲϳ ͲϬ͕ϲϳ ͲϬ͕ϲϳ ͲϬ͕ϲϲ Ͳϭ͕ϰϴ Ă Ϭ͕ϬϬϲϲ Ϭ͕ϬϬϲ Ϭ͕ϬϬϲ Ϭ͕ϬϬϱϱ Ϭ͕ϬϬϯ ď ϯ͕ϬϱϴϮ ϯ͕ϬϱϴϮ ϯ͕ϬϱϴϮ ϯ͕ϭϭϱϭ ϯ͕ϯϯϮϲ D Ϭ͕ϬϮ Ϭ͕ϱ ƐĞǆƌĂƚŝŽ ϰϱ ŝŽǇŶ ŵĞƚŚŽĚ s/d s/d s/d y^ D^z ĚŝĂŐŶŽƐŝƐ ŶŽ &ƵůůǇǆƉ ^ƵƐƚĂŝŶĂď KǀĞƌǆƉ ^ƵƐƚĂŝŶĂď

Tab. 12 (continue) - Biological parameters used for the various stock assessments of sardine and corresponding methods of analysis and diagnosis (synthesis from the GFCM and COPEMED documents). FullyExp = fully exploited, OverExp = overexploited, Sustainab = sustainable exploitation.

ϮϬ Tab. 13- Biological parameters used for the various stock assessments of hake and corresponding methods of analysis and diagnosis (synthesis from the GFCM and COPEMED documents) or available in the literature. FullyExp = fully exploited, OverExp = overexploited, Sustainab = sustainable exploitation. * from the GFCM assessment forms, ** from Zoubi 2001, *** from Bouaziz et al., 1998 and ALDEM survey, 2012.

Ϯϭ 3. Current approaches and methods used to define stock boundaries Up to now, from the available information on the Alboran Sea sardine and hake fisheries summarized above there is no strong evidence of separate or shared stock units of these two species. It is still impossible to reduce uncertainties on stock boundaries, an objective of paramount importance, particularly in a general context of overexploitation, because different population groups of the same species may react differently to the fishing pressure and therefore present different resilience level. As a consequence, the effects of fishing pressure on a species in one area can be different from the effect in a neighbouring area and this differences should be taken into account when establishing management measures. The importance of delimitation of stocks in the Alboran Sea has been highlighted by the 39th Session of GFCM and the 18th session of its Scientific and Advisory Committee. At its 9th Session of the Coordination Committee the CopeMed II project decided to convene an experts meeting (3-6 April 2017) to discuss about potential methods for the identification of stock units in the Alboran sea.

The need to improve the knowledge of the stock boundaries is now widely recognized as a fundamental step for the purposes of assessment and management; various methods are implemented by Regional Fisheries organizations like ICES, NAFO and ICCAT to reach this goal. In particular the Stock Identification Methods Working Group of the International Council for the Exploration of the Sea (ICES/SIMWG) provides annually advances in the following stock identification methods: Genetic Analysis: genetic data can increase the knowledge of stock structure, providing information on genetically distinct groups that is relevant to improved management practices. However, literature data show that inferring demographic stock boundaries using genetic data alone could lead to erroneous conclusions for fishery management purposes. There is a general lack of research investigations integrating genetic studies with other disciplines for pursuing a multidisciplinary approach to stock identification. Fisheries management aims to improve exploitation maintaining the populations within secure limits. The genetically distinct groups of an exploited species not always can be considered a solution when applying management approaches, particularly if an exploited stock is composed by two or more genetics units.

Life history parameters: life history characteristics play an important role in the management and assessment of a species. They provide information on how productive and resilient a species may be and how much harvest they can sustain. Life history parameters like horizontal, vertical and temporal distributions of life stages, reproductive characteristics, growth rates and natural mortality provide important information to both the general understanding of the species’ biology and stock assessments. Body Morphometrics: morphometric analysis is a traditional approach to stock identification. Tagging (conventional, acoustic, satellite): animal tracking methods using traditional or electronic tags can be used to inform movements among management areas and stock mixing and also to estimate some biological parameters as growth and reproduction areas and periods.

Analysis of calcified structures: otolith chemistry can be applied as a stock identification tool. Fish otolith composition is thought to reflect both endogenous processes and external

ϮϮ factors, some of which relate to the surrounding environment, and therefore may be used as a tool for stock discrimination. Analysis of a suite of elements (Li, Na, Mg, K, Mn, Zn, Rb, Sr, Sn, Ba) can reveal significant differences in otolith elemental composition across nursery grounds providing a means for understanding the supply of juveniles from specific nursery grounds and adult stocks.

Parasitology: parasites may be useful as biological tags for stock identification when the source and site of the infection are known and the parasite has a sufficiently long life, and especially when infection by the parasite occurs on a spawning ground

Larval dispersion: Beside the problems to identify the areas, extension and periods of the reproduction , it is difficult to map directly how far and in what directions larvae disperse, but the dispersal patterns of larvae must be considered when conducting stock discrimination studies. Larval dispersal can be responsible for the lack of genetic differentiation between relatively very distant areas.

Interdisciplinary analysis: single technical approaches are often insufficient to delineate stocks and interdisciplinary approaches often perform better; published information from different marine disciplines such as geomorphology, ecology and fisheries, with the analysis of new data coming from official fishery statistics and scientific surveys should be combined.

Figure 25 shows a scheme recently published by the ICES/SIMWG, representing a global logistics approach matching research needs on population structure and stock delineation (inside the dashed circle) with current discipline-specific expertise (rectangles) to improve decision-making processes (ellipses) for fisheries sustainability

Ϯϯ Fig.25- global logistics approach to improve decision-making processes (from Pita et al., 2016).

In the Mediterranean the use of this type of muldisciplinary approach is still very rare. It has been used by Quetlas et al. (2012) in order to identify possible stock boundaries between the Balearic Islands (GSA05) and the adjacent ones of the Iberian Peninsula (GSA06). This work was based on published information from different marine disciplines such as geomorphology, ecology and fisheries, combined with the analysis of new data coming from official fishery statistics and scientific surveys. According to the available information they were able to conclude that “tŚŝƐ ĂƉƉƌŽĂĐŚ ĂǀŽŝĚƐ ƚŚĞ ŝŵƉŽƌƚĂŶƚ ĚƌĂǁďĂĐŬƐ ;ŝŶĐŽŶĐůƵƐŝǀĞ ƌĞƐƵůƚƐ͕ ŚŝŐŚĐŽƐƚƐͿŽĨŽƚŚĞƌƚŝŵĞͲĐŽŶƐƵŵŝŶŐƚĞĐŚŶŝƋƵĞƐƵƐĞĚŝŶƐƚŽĐŬŝĚĞŶƚŝĨŝĐĂƚŝŽŶ͕ƐƵĐŚĂƐŐĞŶĞƚŝĐƐ͟ĂŶĚthat GSA05 should be maintained as an individualized area for assessment and management purposes in the western Mediterranean. More recently an international initiative to apply this type of global approach has been achieved in the frame of the STOCKMED project (Fiorentino et al., 2014); STOCKMED was a European-funded project tackling the identification of stock units and their boundaries for 19 species of commercial interest in the Mediterranean. This study is based on available data relative to any field that is considered key for the multidimensional identification of stocks: life history traits and information coming from fisheries, biological research (e.g. biometry, parasites, physical tagging, multiple genetic markers, species mobility, characteristics and duration of embryo and larval phases, growth parameters, etc.), indicators estimated from scientific surveys, hydrology and topography within the appropriate spatial scale. The view gathered by the project is mainly localized in the European region of the Mediterranean, however the lack of knowledge in different key disciplines was experienced throughout the project and In some cases the available information was insufficient for stock unit identification. Despite the difficulties of integrating in a rigorous analytical procedure different types of information, the methodology developed allowed to identify possible geographical stock configurations for most of the investigated species, including the assessment of their uncertainty. Although with some differences in species, results suggested that most of the existing GSAs should be aggregated for assessment purposes according to a longitudinal gradient.

This study is the first example of distribution of stock units in the Mediterranean according to a holistic and standardized approach and based on the current knowledge available, to be validated through specific studies or the collection of supplementary/independent information. It is an excellent starting point to improve the knowledge of the distribution of the stocks in the Mediterranean and the following general remarks reported by the STOCKMED project should to be taken into consideration for the future Mediterranean stock identification projects:

• Scientific surveys are the most adequate platform to produce standardized and comparable data throughout the Mediterranean. However, there is a lack of availability of information regarding regular scientific surveys of non-EU GSAs. Moreover, the annual periodicity of the scientific surveys is not adequate to tackle inter-annual variations in the biological parameters.

• The biological parameters from bibliographic review, the degree of the spatial coverage of studies varies greatly between species and parameters. Overall growth and reproduction studies provide a spatial coverage much wider than the spatial coverage provided by studies reporting on other indicators. The different methods used to estimate the growth parameters

Ϯϰ provide significantly different estimates of growth and should be used with caution in order to ensure comparability among areas. There is a need to increase the validation and the intercalibration of approaches.

• Knowledge in the Mediterranean regarding meristic/morphometry, otolith shape and otolith micro-structure is pretty scarce and limited to some species and areas

• Most of literature on parasites is related with the biology of the parasites or of the host species rather than with establishing baselines for fisheries management.

• There are very scanty studies regarding the tagging/migration of the Mediterranean species others than tuna and swordfish.

• Regarding larval drift, data concerning larval development of fishes and decapods are scarce. The bathymetric distribution of larval stage for most Mediterranean species is still poorly known, and some aspects of early life history like behavior, food consumption or natural mortality have not yet been explicitly incorporated into bio-physical models.

• For most of the species the geographical coverage of genetic data is very poor and sporadic or inexistent; not enough sampling and/or not enough loci have been analysed.

• The current knowledge on the ecology of meroplanktonic stages (ontogenetic changes, vertical distributions and migrations, growth and mortality) is very limited and studies focusing on population integrity through larval transport are very scant. Hence, the inference of connectivity between spawning and nursery areas and/or between adjacent GSAs is very difficult, if possible.

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Ϯϳ