9-11 October 2017 Malaga, Spain

Transcription

1 TECHNICAL DOCUMENT 48 REPORT OF THE 6TH MEETING OF THE COPEMED II STUDY GROUP ON DEMERSAL AND SMALL PELAGIC STOCKS OF INTEREST TO ALGERIA, MOROCCO AND SPAIN IN THE ALBORÁN SEA (GSA 01, 02, 03, AND 04) 9-11 October 2017 Malaga, Spain

2 CopeMed II Technical Documents Nº48 GCP/INT/028/SPA; GCP/INT/006/EC REPORT OF THE 6 TH MEETING OF THE COPEMED II STUDY GROUP ON DEMERSAL AND SMALL PELAGIC STOCKS OF INTEREST TO ALGERIA, MOROCCO AND SPAIN IN THE ALBORÁN SEA (GSA 01, 02, 03, AND 04) October 2017

3 The conclusions and recommendations given in this document and in other documents in the Co-ordination to Support Fisheries Management in the Western and Central Mediterranean CopeMed II Project series are those considered appropriate at the time of preparation. They may be modified in the light of further knowledge gained in subsequent stages of the Project. The designation employed and the presentation of material in this publication do not imply the expression of any opinion on the part of Food and Agriculture Organization of the United Nations, FAO, the Government of Spain or the Commission of the European Union concerning the legal status of any country, territory, city or area, or concerning the determination of its frontiers or boundaries. This document has been financed by the European Union and the Government of Spain. The views expressed herein can in no way be taken to reflect the official opinion of the European Union or the Government of Spain.

4 Preface The CopeMed II Project on Co-ordination to Support Fisheries Management in the Western and Central Mediterranean is executed by the Food and Agriculture Organization of the United Nations (FAO) and funded by the Government of Spain, represented by the Secretaría General de Pesca (Mº de Agricultura, Alimentación y MedioAmbiente, MAGRAMA), and the European Union, represented by the European Commission (EC).The premises of the project at the Subdelegación del Gobierno in Málaga (Spain) are part of the Spanish contribution included in the agreement with the FAO. The objective of the project is to maintain the sustainability of the marine fisheries in the central and western Mediterranean Sea and its ecosystem, taking into consideration environmental, biological, economic, social and institutional issues. In addition, the project will continue to reinforce the collaboration among the participating countries of the sub-region by facilitating their participation in the activities of the Scientific Advisory Committee (SAC) and in the General Fisheries Commission for the Mediterranean (GFCM). Regions covered by CopeMed II are the western and central sub-regions of the Mediterranean. Participating countries are Algeria, France, Italy, Libya, Malta, Morocco, Tunisia and Spain. The main beneficiaries are the fishery policy-makers, managers and fishery administrations in the western and central Mediterranean countries. The project is also contributing to the strengthening of regional collaboration by supporting the participation of the countries in relevant regional scientific organizations, such as the FAO s General Fisheries Commission for the Mediterranean (GFCM). Secondary beneficiaries include the national research institutes, fishers and fishers associations, and industrial organizations. Project CopeMed II (FAO-FIRF) Subdelegación del Gobierno en Málaga Paseo de Sancha 64, Oficinas Málaga España Tel: (+34) Fax: (+34) copemed@fao.org URL: 1

5 CopeMed II (GCP/INT/028/SPA GCP/INT/006/EC) Publications CopeMed II project publications are issued in the CopeMed Technical Documents series and are related to meetings, missions and research organized or conducted within the framework of the CopeMed II Project. Comments on this document would be welcomed and should be sent to the Project premises: Project CopeMed II (FAO-FIAF) Subdelegación del Gobierno en Málaga Paseo de Sancha 64, Oficinas Málaga (España) For bibliographic purposes this document should be cited as follow: CopeMed II Report of the 6 th Meeting of CopeMed II Study Group on demersal and small pelagic stocks of interest to Algeria, Morocco and Spain in the Alboran Sea (GSAs 01, 02, 03 and 04). Malaga, Spain 9-11 October CopeMed II Technical Documents Nº48 (GCP/INT/028/SPA - GCP/INT/006/EC). Malaga, pp. 2

6 Preparation of this document This document is the final version the ad hoc Meeting of CopeMed II Study Group on demersal and small pelagic stocks of interest to Algeria, Morocco and Spain in the Alboran Sea (GSAs 01, 02, 03 and 04). Malaga, Spain, 9-11 October Acknowledgements CopeMed II acknowledges the participation and valuable contributions of all experts from CNRDPA (Algeria), INRH (Morocco), IEO (Spain) in the ad hoc CopeMed scientific Working Group between Algeria, Morocco and Spain on the fisheries and fishery resources of demersal species in the Alboran Sea. CopeMed II Report of the 6 th Meeting of CopeMed II Study Group on demersal and small pelagic stocks of interest to Algeria, Morocco and Spain in the Alboran Sea (GSAs 01, 02, 03 and 04). Malaga, Spain 9-11 October CopeMed II Technical Documents Nº48 (GCP/INT/028/SPA - GCP/INT/006/EC). Malaga, pp. ABSTRACT The sub-regional Study Groups among Algeria, Morocco and Spain on demersal and small pelagic stocks in the Alboran Sea area (GSAs 01, 02, 03 and 04) are specific study groups created within the framework of the CopeMed Working Groups which intend to reinforce the cooperation and prepare assessments of the stocks of common interest among the three countries of the Alborán sea. The two Study Groups met in parallel on the 9-11 October 2017 in Málaga, Spain. Two assessments were done using XSA method with data combined of GSAs 01 and 03 for hake and sardine. The assessment of hake resulted in overexploitation status, whilst sardine was considered sustainably exploited with some uncertainties. In addition preliminary assessments of data combined in the three GSAs (01, 03 and 04) were tested by a production model (BioDyn) and pseudocohort analysis (VIT) for hake, deep-water pink shrimp and sardine. The stock status resulted overexploited for the two demersal and sustainably exploited for sardine. The group agreed to transmit the corresponding stock assessment forms to the working groups of the GFCM to be held from November

7 Report of the Meeting of CopeMed II Study Group on small pelagic and demersal stocks of interest to Algeria, Morocco and Spain in the Alboran Sea (GSAs 01, 02, 03 and 04) Malaga, Spain, 9-11 October OPENING AND OBJECTIVES OF THE MEETING The meeting convened, in parallel, the two Study Groups, the 6 th meeting of the SG on demersal species and the 5 th meeting of the SG on small pelagics and was held at the CopeMed II premises in the Subdelegación del Gobierno in Málaga, Spain. It was attended by experts from Algeria (CNRDPA), Morcco (INRH), Spain (IEO) and the CopeMed staff. (List of participants in Appendix II). The meeting was opened by Ms Pilar Hernández from CopeMed who welcomed the participants of the three institutions and introduced the objectives and expected results. She recalled recommendations from previous meetings of the CopeMed Study Group and also from the GFCM working groups on stock assessment and the SRC-WM meeting. The most relevant recommendations were: i) to investigate sock boundaries, ii) to incorporate data from the Western part of Algeria to the joint assessment; iii) continue assessing hake jointly in GSA 01 and 03; iv) continue doing separate and joint assessments for sardine in GSA 01 and 03 and compare the results, besides the investigation of stock boundaries; v) improve and complete data from direct methods. The expected outputs were to update the assessments of hake and sardine in GSAs 01 and 03 done last year and produce preliminary assessments for GSAs 01, 03 and 04 for sardine, hake and deep-water pink shrimp. 2. INTRODUCTION OF DATA BY THE NATIONAL EXPERTS AND SELECTION OF MODELS Experts from the three countries introduced the data made available to the group. After discussion and a thorough analysis of the available data, the group agreed on the possible assessments to be prepared. After compilation of all information and data provided by experts, two expert s teams were created for the demersal stock assessment exercise. Considering that exclusively, landings series of nine years ( ) in Spain and Morocco were available, the group agreed to perform an XSA analysis exercise only for GSAs 03 and 01 using R software. The second team should carry out the joint stock assessment in GSAs 01, 03 and 04 using pseudocohort analysis of two years ( ) with VIT for hake but also for deep water pink shrimp, provided that data of the same years ( ) were available in the three GSAs. For small pelagics, two sub-groups were also created; the first team would prepare a joint assessment for sardine in GSAs 01 and 03 using XSA with data from ( ) and the second one would perform an exercise with two methods: Global Production Model (BioDyn) using Morocco, Algeria and Spain data from and the survey indices from Morocco and another trial with VPA model in VIT for the only year in common (2016) pseudocohort analysis of the three GSAs combined. It has to be 4

8 noted that data from GSA 04 are exclusively from the western part (ports of Gazhaouet and Beni Saf) belonging to the Alboran sea. The summary of the fishery in each country is described here below. JOINT ASSESSMENTS HAKE IN GSAs 01 and 03 Description of Fisheries Spain European hake is a target demersal species of the Mediterranean fishing fleets. It is largely exploited in GSA01, mainly by trawlers on the shelf and slope (91% landings), but also by small-scale fisheries using long lines (3%) and gillnets and trammel nets (6%) (average percents estimated between 2013 and 2016). The trawler fleet (117 boats in 2016) is the largest in landings (168 tons in 2016). Morocco The trawl fishing fleet in Moroccan GSA 03 is heterogeneous. The number of trawlers operating in GSA 03 is 72. M. merluccius in GSA 03 is found at depths ranging from 50 to 510 m. In the period , the mean annual M. merluccius production was 110 tons. Landings in GSA 03 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 M. merluccius production (94%) and with regards to the fishing effort (91%). In 2016, the number of trawlers targeting M. merluccius in GSA 03 was 72 with an average engine power of 230 HP and a mean GRT of 50 Tx (Table 1). Long liners are not found in Moroccan GSA 03. Table 1. Fleet characteristics in Moroccan GSA 03. Ports Number of Mean HP Mean GRT trawlers Nador Al Hoceima M diq Total Algeria Landings in GSA 04 come from two fishing areas (Ghazaouet and Beni Saf), the two most important ports in terms of M. merluccius production (96.04 %). Trawlers fleet in this area has an average engine power of HP and a mean GRT of 57 TX (Table 2). Table 2. Mean fleet Segment characteristics in Algerian GSA 04 (Data of 2012) Ports Number of trawlers Mean HP Mean GRT Ghazaouet Beni Saf A summary of number of vessels, catches of hake and effort in number of days averaged for the last four years is presented in table 3 5

9 Table 3. Number of vessels, catch, and effort by country averaged by recent years (see notes below) Fleet Operational Effort (n of Catch (T) Units (days) boats) Trawls- GSA * 272* 16723* Trawls- GSA03 72* 131* 7213* Trawls- GSA04 99** 105** 9047** Total * average ) **Average ( ) Hake annual landings in the period and its CPUE in the period in GSA 04, issued from official statistics (MPRH, 2016), are showed in figure 1. The greater part of the European hake production is targeted in Ghazaouet area. The plot emphasized the decrease in the catch production. The minimum landing in GSA 04 was 82.7 tons, it was observed at In this period ( ), the average annual landings of this species was tons. The increase of M. merluccius landings in Ghazaouet ports compared with Beni Saf ports was observed after 2013, which could be explained by the relocation of trawlers in the first area. The maximum catch per unit of effort (CPUE) was recorded in the period (Figure 2) Figure 1. Trawlers landings of M. merluccius (GSA-04) 6

10 Figure 2. Trawlers CPUE of M. merluccius (GSA-04) The data selected for the analysis with XSA are catches from 2007 to Length frequency data for the same period coming from monthly on-board and port sampling in Morocco and Spain. Length composition was converted to catch-at-age by using cohort slicing. Landings have shown important oscillations along the period of the data series. However, in the last six years from 2011 onwards, a decreasing trend in landings is observed with the minimum values in the time series data (280t). (Figure 3). Length frequency distribution in the period are shown in Figure 4. Trends in CPUE and composition of landings after application of age slicing are shown in Figure 5 and 6. Figure 3. Merluccius merluccius landings in GSAs 01, 03 and total 3, historical trend 7

11 Figure 4. Length frequency distribution: a/ (Total length) of Trawl catches in the geographical sub-area 1+3 for the period ( ). b/ Average Size compositions by GSA CPUE_GSA1-3 kg/day CPUE_GSA1 cpue (k/days)_morocco kg/day CPUE_GSA3 20 kg/day cpue (k/days)_spain Figure 5. Catch per unit of effort (kg/fishing days) for Hake in GSA01-3 (Trawl fleet) 8

12 Figure 6. Age structure of the catches in GSAs 01 and 03 for the period Model runs Hake: XSA Model As recommended by the last session of the GFCM-WGSAD the group decided to use XSA to assess the stock of European hake jointly combining GSAs 01 and 03. The data from the two countries were summed up in a file and the corresponding data sets needed to run XSA were created. Length-weight relationship and maturity ogive comes from Spanish and Moroccan biological sampling ( ) and the vector of natural mortality by age was calculated from Caddy s formula, using the PROBIOM Excel spreadsheet (Abella et al., 1997). Biological sampling for Maturity and Length-Weight relationships. For the choice of the set of biological parameters, experts discussed from their own experience and decided to adopt the values of Mellon & Duval (2010). The software used was the Lowestoft suite (Darby and Flatman 1994) and FLR (Fisheries Libraries in R). In addition, to obtain reference points, Yield-per-Recruit (Y/R) and Spawning-per-Recruit (SSB/R) analyses was conducted based on the exploitation pattern resulting from XSA model and population parameters. Tuning data: MEDITS surveys ( ) and Moroccan Mediterranean survey ( ) all converted to n/km2 instead of kg/km2. In figures 7, 8 and 9 the spatial distribution of the last year abundances and historical trends are provided. 9

13 Figure 7. MEDITS_ES trawl survey Hake Spatial distribution of estimated abundances. Figure 8. GSA3 trawl survey hake Spatial distribution of estimated abundances in Figure 9. Trends in abundance indices (Kg/km 2 ) for GSA01 and Kg/hour for hake in 10

14 GSA03 Summary of Input data and Parameters Catch time series (official landings and Discard data) from trawl fleet. Length distributions (monthly onboard and port sampling). Catch-at-Length data converted to Catch-at-Age data using cohort slicing. Growth Parameters from Mellon et al, 2010 and DCF-Spain (2012). Biological sampling for Maturity and Length-Weight relationships. M vector by age using PROBIOM spreadsheet (Abella et al, 1998). Tuning data from MEDITS survey and commercial fleet, and ( ) from Moroccan survey. The model was run with different combinations of settings, the best model fit (with minimum residuals) and the best retrospective analysis were chosen for the optimum set of parameters which are summarized below. The results of XSA for the four indicators: Biomass, Recruitment, Catch and Fishing Mortality are shown graphically in figure 10 and in tabular format in table 4. Summary of the Main model Settings for hake in GSAs 01 and 03 Ages 0 to 5+ (Age 5 is a Plus Group) Fbar 0-4. Catchability independent of age for ages older than 2. Survivor estimates shrunk towards the mean F of the final 3 yrs or the 2 oldest ages. S.E. of the mean to which the estimates are shrunk = 1 Minimum standard error for population estimates derived from each fleet = 0.3. Figure 10.XSA results for hake in GSAs 01 and

15 XSA results show that Spawning biomass (SSB) and yield (Y) show a decreasing trend from 2011 to Recruitment (R) showed fluctuations over the all series, increasing in the last year. Fishing mortality (Fbar0-4) showed a decrease from 2012 to Table 4: Values of the main indicators of the stock status as resulting from XSA GSA Stock Year FBAR0-4 Fbar-Range Recruitments (thoussb(t) Total biomasse Catches (t) 1&3 HAKE , , ,28 503, , , ,86 425, , , ,68 769, , , ,79 675, , , ,32 848, , , ,61 615, , , ,31 497, , ,29 911,15 357, , ,94 929,04 280, , , ,62 282,52 Yield per recruit analysis in XSA Yield per recruit analyses was conducted based on the exploitation pattern resulting from the XSA model and population parameters. Minimum and maximum ages for the analysis were considered to be age group 0 and 5. Stock weight at age, catch weight at age and maturity ogive was estimated as mean values between 2007 and Natural mortality vector values were applied per age group using ProBiom (Abella et al., 1998). Fishing mortalities were the mean exploitation pattern F between 2013 and Reference F was considered to be mean F for ages 0 to 4 during the last 3 years ( ). Figure 11 Yield per recruit curve, including the corresponding yield reference point (F 0.1 = 0.19, F max =0.3, F status quo = 1.7) 12

16 Current F (F curr = F BAR 0-4 ) was estimated to be 1.7. F curr exceeds F 0.1 reference point (0.19) with a ratio between F curr and F 0.1 of 8.9 indicating that the stock is subjected to over-fishing (or overexploitation) and overexploited with a level of biomass (1185 in thousands) below the 33 rd percentile (1244). VIT Model - Joint assessment of hake in GSAs 01, 03 and 04 Data and methods The study group agreed on using available data from Spain, Morocco and Algeria ( ) for the M. merluccius stock assessment. Length-frequency distribution in GSAs 01, 03 and 04 collected from commercial catch (obtained from monthly sampling on port) and the official landings were used in this analysis. Growth parameters of Von Bertalanffy and length weight relationship validated by the scientist group are those obtained by García et al. (2009) in the GSA 01. L :108, K:0.21, t0:-0.115, a: , b: , M: 0.4 (average from the vector at ages 0 to 5+ by ProBiom). The three countries were considered as three different fleet exploiting the same stock unit to run a joint assessment. Percentage of production of each country, considered like a gear proportion of exploitation. Several VPA and a yield per recruit (Y/R) analysis with different terminal fishing mortality values were carried before choosing the best fitted for the next analysis. Results Once the length cohort analysis (LCA, cm) was applied, after carrying out a slicing, a distribution with 6+ age classes was obtained (Figure 12 shows the population structure with the VPA). After this first step, the group used four different F terminal values (0.2, 0.5, 1 and 1.5) and pointed out that ages are relative to the first length of the analyses. Figure 13 shows the results for F by age for the four different values of terminal F. Figure 12. Population in numbers and Biomass of pseudocohort analysis in GSAs 01, 03 and

17 The study group agreed to take the VIT results for the terminal F = 0.5 as the best round to continue the Y/R analysis. It indicates that age classes 1-4 (Figure 14) are the most exploited in Alboran Sea. Figure presents the VIT results for F by length classes. Figure 13. Fishing mortality per age for different value of terminal F. Figure 14. Fishing mortality by age (GSA 01_03 and 04). For this analysis, the current F value (F current = 1.84 y -1 ) corresponds to the average mortality F of age classes ranging from 1 to 4 years (Fbar 1-4) for GSA (1+3+4). For each GSA separately, F current was obtained by the average of 0-3 group for GSA 04, from 1-4 years for GSA 03 and 1-3 age group for GSA 01 as those were considered the most exploited ages in each country. The group discussed about the pertinence of using different age ranges to estimate F in the three GSAs separately and noticed that the sum of the three Fs obtained cannot be 14

18 considered as the total F of the three combined. Questions about this inconsistence were decided to be addressed to the WGSAD of GFCM. Yield per recruit analysis in VIT hake in GSAs 01_03 and 04 In (fig. 15) the Y/R curve and biological reference points F0.1 FMSY show that actual level of fishing mortality (F current = 1.84) is higher than the values calculated for the FMSY proxy (F0.1 = 0.39), which indicates that the current European hake stock is in overfishing status. Experts recommended reduction of the fishing mortality of 77 % in the current trawl fishery in the GSAs 01, 03. Figure. 15. Yield per recruit curve and reference points hake in GSAs 01, 03 and Joint stock assesement of hake using VIT in GSAs 01 and 03 With the aim to compare results by using different methods, the Group decided to run VIT Pseudocohort analysis and compare this results with those obtained by XSA. Data and methods Another VPA analysis was proposed to assess hake stock in the GSAs 01 and 03. This analytical assessment exercise was carried out using Moroccan (GSA 03) and Spanish (GSA 01) length composition (LC, cm) data to make the pseudo-cohort analysis with terminal fishing mortality F=0.5. The two countries were considered as two different fleets After carrying out a slicing of (LC, cm) of the both GSAs 01 and 03, a distribution with 5+ age classes was obtained (Figure 16 shows the population structure with the VPA). Figure 17 shows the results for F by age for a terminal F equal to 0.5 y

19 a b Figure 16. Biomass (a) and population in numbers(b) of pseudocohort analysis in GSAs 01 and 03 Figure 17. Fishing mortality F per age of M. merluccius from GSAs 01 and 03. The actual level of fishing mortality (Fbar = 1.20) is higher than the values calculated for the FMSY proxy (F0.1 = 0.28) which indicates that the stock is in overfishing status. Considering the results of the assessment exercise, the scientist group recommended a 77 % reduction of the fishing mortality in the current trawl fishery in the GSAs 01 and 03. Figure 18 Yield per recruit and reference points of Hake in GSAs 01 and 03 16

20 The results of XSA provided a higher value of Current F (Fcurr = FBAR 0-4) was estimated to be 1.7 and a lower value of F0.1 reference point (0.19) with a ratio between Fcurr and F0.1 of 8.9 indicating that the stock is in overfishing status. In the case of VPA only the last two years ( ) have been considered and the ratio is 4,28, still in overfishing status but with lower fishing mortality. DEEP WATER PINK SHRIMP IN GSAs 01, 03 and 04 Description of Fisheries Spain Deep-water pink shrimp (Parapenaeus longirostris) is one of the main crustacean species for trawl fisheries in the GFCM geographical sub-area Northern Albopran (GSA 1, Spain). It is an important component of landings in some ports and occasionally a target species of the trawl fleet composed of approximately 100 vessels (average ), that operates on the upper slope (Fig 19). The annual landings (Y) showed a very sharp decrease at the beginning of the maximum observed in 2009 (250 t). Landings remained relatively stable during the period , fluctuating around 100 t, and increased in 2016 increased slightly to 133 t in Abundance indices from MEDITS trawl survey, showed the same trend (Fig 20). Fig. 19 Abundance Indices (Num./Km2) and geographical distribution of Parapenaeus longirostris from MEDITS_ES Trawl survey (2016) in GSA Abundance (N/km2). MEDITS_ES CPUE_GSA N/Km CPUE (K/Fishing days) year Fig. 20 CPUE (K/fishing days) from commercial fleet and Abundance Indices (Num./Km2) of Parapenaeus longirostris. 17

21 Morocco The trawl fishing fleet in Moroccan GSA 03 is heterogeneous. The number of trawlers operating in GSA 03 is 72. Parapenaeus longirostris in GSA 03 is found at depths ranging from 100 to 300 m. In the period , the mean annual Parapenaeus longirostris production was 258 tons. 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 Parapenaeus longirostris production (86%) and with regard to the fishing effort (84%). In 2016, the number of trawlers targeting Parapenaeus longirostris in GSA 03 was 72 with an average engine power of 230 HP and a mean GRT of 50 Tx (Table 5). Table 5. Segment fleet characteristics in Moroccan GSA 03. Ports Number of Mean HP Mean GRT trawlers Nador Al Hoceima M diq Total Algeria The demersal species with great commercial interest in Algeria are Merluccius merluccius, mullus barbatus, Pagellus acarne, Octopus vulgaris, Aristeus antennatus and Parapenaeus longirostris. Parapenaeus longirostris is present throughout the Algerian coast from east to west from 50 to 600 meters depth with a high abundance between meters. Sizes range from 13 to 41 mm in cephalothorax length, with an average in the catch of 25,27mm. The minimum size of the deep-water pink shrimp is set to 20 mm cephalothorax length. Sex ratio is slightly in favor of females (54.06%). GSA 04 is extended from the Moroccan boundaries at the west until the Tunisian ones in the eastern part. Regarding the geographical limit of the Alboran sea, the catch data and biological sampling used in this assessment exercise come exclusively from two ports: Ghazaouet and Béni saf) (Fig 3). The landings of Parapenaeus longirostris in these ports represent about 22% of national production and the mean landings by year are estimated to 967 T from 2013 to In 2016, the 51 trawlers operating in the ports of Ghazaouet and Beni saf are in average 19 meters length, 501 HP power and tonnage of 45 GRT. The total number of fishing days is 9047 days. In terms of regulation, namely in Algeria trawling is prohibited from 0-50m depth. There is a closed season from 1may to 31 August for trawlers under 3 miles.the mesh size of the cod end is 40 mm. 18

22 Figure 21. Localization of the two algerian ports of Alborán sea considered for this assessment. Table 6. Segment fleet characteristics in GSA 04. (2016) Ports Number of trawlers Mean HP Ghazaouet Mean GRT Béni saf Regarding the evolution of catches and fleets table 7 and figures 22 and 23 shows yearly catches in the three countries and in Algeria. Table 7. Catches and fleet numbers as used in the assessment (tonnes) Year Landings GSA 04 (t) Landings GSA 01 (t) 259,34 140,05 161,28 46,767 71,44 97, , , , ,88 212,83 247,66 238, , ,55 171,93 109,90 65,54 78,32 125,89 249,89 96,37 169,03 238,65 147,10 95,22 101,35 133,34 Landings GSA 03 (t) 683,5 512,8 465,8 198,7 182,5 334,1 591,88 387,69 494,48 657,22 476,14 298,01 231,16 244,14 Fleet:OTB (GSA1) Fleet:OTB (GSA3) Fleet:OTB (GSA4)

23 LANDINGS (T) GSA 1 GSA 3 GSA Figure 22. Landings in the three countries in the time series ( ) GSA 04 Trawlers Catch (T) Number Figure 23. Parapenaeus longirostris landings (GSA-04) and number of trawlers VIT Model Figure 24. size distribution by Carapace length (mm) ( ) - Joint assessment of deep water pink srimp in GSAs 01, 03 and 04 With the available data, the study group tried to update the assessment done in 2011, after several attempts, the group decided to use pseudo-cohort analysis by VIT for two years of data (2015 and 2016), which are the only years with data in common. 20

24 Moroccan (GSA 03), Spanish (GSA 01) and Algerian length composition (LC, mm) data were used to make the pseudo-cohort analysis. Data and methods Biological input data for relative and absolute growth, natural mortality (M) and maturity at age were also discussed and finally the group decided the values shown in table 8. Length composition data were introduced in VIT software considering that each GSA is a different fleet. Automatic slicing by VIT was used to convert lengths to ages. The three countries were considered as three different fleet exploiting the same stock unit to run a joint assessment. Percentage of production of each country were considered like a gear proportion of exploitation. Table 8: growth parameters and length/weight relationship for p. longirostris as agreed Biological information Units Sex female male Combined L mm 45* Years Growth model Length-Weight relationship K y * t 0 y Data source *García et al GSA-01 a * b * Sex ratio (% of Females/Total) 0.5 (Mal/Fem) Results of VIT for deep water pink shrimp in GSAs 01, 03 and 04 The results of the catch in numbers by age from the VIT software are represented by the figure 25 showing that for the three GSA most part of the catches are concentrated on the age 2. Figure 25. Catch in numbers by age. 21

25 Figure 26. Fishing mortality per age in the three fleets separately and total Figure 27. Yield per recruit in the three fleets separately and total In table 9 the different values of F estimated separately and combined are shown. It has to be noted that to estimate F in each GSA, the ages most affected by the fishery were taken into consideration. This can be misleading as the sum of the three GSAs s F cannot be taken as F total. The Group decided that questions regarding the pertinence of such distribution of F had to be addressed to the WGSAD. 22

26 Table 9. Results of the yield per recruit analysis (VIT). GSAs F 0.1 F current F max F current /F 0.1 Joint assesment GSAs GSA (age 1-5) GSA (age 1-4) GSA (age 1-5) GSA (age 1-4) The actual level of fishing mortality (Fbar = 1.29) for the joint GSA is higher than the values calculated for the Fmsy (F0.1 = 0.30) showing that the stock status is currently overfished. Even for each GSA separately and with the best age ranges for Fbar, the F current is higher than the F 0.1, the proxy for F MSY. Relative intermediate biomass; B current= 1400 (t); biomass between the 33 rd and the 66 th percentiles. The ratio of Fcurrent/F0.1 is in any case higher than 4, showing a high level of overexploitation. These results are very similar to those obtained in the previous assessment done in 2011 SARDINE IN GSAs 01 and 03 Description of Fisheries Spain The current fleet in GSA 01 the Northern Alboran Sea is composed by 87 units, characterised by small vessels, average TJB % of them are smaller than 12 m (operational Unit 1), 84% > 12 m (operational Unit 2), and no one bigger than 24m. The purse seine fleet has been continuously decreasing in the last two decades, from more than 230 vessels in 1980 to 87 in 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 countries. Subsequently the fleet continued to decline but more slowly. Although sardine has a lower price than anchovy is an important support to the fishery as it is the most fished species. Catches of sardine in the period has been highly variable, with a minimum of 3000 tons in Higher catches occurred in 1992 (11000 tons). All period average is about 6000 tons. Species with a lower economic value are also captured, sometimes representing a high percentage of landings: horse mackerel (Trachurus spp.), mackerel (Scomber spp.), and gilt sardine (Sardinella aurita). The interest about some of these species has been increasing because there is a new market for them; gilt sardine and mackerel, especially the first, are sold for tuna farming. A requirement for such sales is a high yield by fishing day, due to its low economic value. In the case of mackerel it is exported to Portugal. Data used in the assessment correspond to EU-Data Collection Framework. Unit of effort has been effective fishing night by species. Series of CPUE shows a very similar profile to catches. (Fig 28). 23

27 12000 Sardine RSM (95%) GSA Landings (tons) bleu cpue (Kg/fishing day) Landings CPUE Fig. 28: Trend in sardine landing and CPUEs, years (Spain) Morocco The moroccan purse seiners fleets targeting sardine last year (2016) in GSA 03 (Moroccan Mediterranean Sea) was composed by 110 vessels, characterized by small vessels, average TJB is 50 tx and 252 horse power. 7% of them are smaller than 12 m (operational Unit 1), 86% of them are between 12 m and 24 m (operational Unit 2), and 7% are bigger than 24m (operational Unit 3). This fleet is based mainly in 4 important ports M'diq, Nador, Al Hoceima and Ras Kebdana with high mobility of seiners between ports following the abundance of resources. In addition there are around one hundred small scale boats fishing in coastal areas that are not considered in this study due to the lack of reliable statistics from this segment. Landings of small pelagic in Moroccan Mediterranean are composed by sardine, sardinella, anchovy, horse mackerel, chub mackerel and others. Sardine and anchovy are the target species of seiners: sardine for its abundance and anchovy for its high commercial value. On the last decade, the total production of sardines in the Moroccan Mediterranean Sea, fluctuates between 7000 and tons/year. Between the years 2007 and 2016, the annual average production of sardines is about tons. Figure

28 Catch (tons) Catch seiners total catch sardine EFFORT Effort (days) Figure 29: Trend in sardine landing and Effort (Morocco) Landings of sardine showed an increase from 2008 to a maximum in Since then landings have decreased, reaching the lowest value in From that year onwards. it showed an increasing trend with the highest value in 2014 (catches represented tons), when landings started to decrease again The analysis of the evolution of fishing effort (expressed in effective fishing days) exerted on the sardine stock between 2007 and 2016 shows that fishing effort has the same trend of catches. (Figure 29) CPUE has a maximum peak in 2007 (2273 kg/day), with a little recovery between 2012 and 2013 but after that CPUE is decreasing. The general evolution shows a decreasing trend. (Figure 30) Total catch (tons) CPUE (kg/fishing day) total catch CPUE Figure 30: Trend in total catch sardine and CPUE, years (Morocco) 25

29 Algeria Small pelagic are the most important resource in Algeria fisheries with more than 70% of the total landings. The small pelagic landings are composed by Sardine Sardina pilchardus, Anchovy Engraulis encrasicholus, Sardinelle Sardinella aurita, horse makerel Trachurus trachurus and others. The active fleet targeting small pelagics in Algerian Alboran region (ports of Ghazaouet and Beni-Saf in GSA 04) is composed mainly by 153 purse seine (2016) and to a lesser degree by pelagic trawlers which are very poorly represented. The seiners are small boats from 6 to 24m lenght with variable power depending on the length of the ship. The engine power and the average gross tonnage is HP and TGB for vessels greater than or equal to 12m. Sardine is one of the species most targeted by this fleet operating in the two ports Ghazaouet and Beni-Saf. The fishery takes place all year around. There are no closing seasons for purse seiners. The average value of Sardine landings for the studied period ( ) is 5728 Tons. The landing fluctuates around a maximum value of Tons in 2007 and a minimum value of 2201 Tons in The current value (2016) is 5587 Tons (Figure 31) Figure 31. Trend in sardine landing (Algeria) Catch per unit effort CPUE generally varies between 337 (2012) and 1694 kg/day (2009) with an average of 814 kg/day. (Figure 32) Figure 32. Trend in sardine landing and CPUEs, years (Algeria) 26

30 The analysis of the series of CPUE from showed a very similar profile to that of sardine landings in the Algerian Alboran sea.(figure 33) Landings(Tons) GSA01 GSA03 GSA04 Years Figure 33. Trend in sardine landing in GSA01, GSA03 and GSA04, years Model runs Sardine: XSA Model Data from the time series on length distribution were transformed to Catchat-Age matrix for GSAs 01 and 03 combined. Tuning data: given the lack of complete series of surveys in GSA 01, abundances index (in thousands) from the Moroccan surveys for GSA03 from 2006 to 2016 were chosen by the group. For those years that the survey was not carried out, abundance values were estimated by averaging the previous and further year when available. Summary of Input data and Parameters Landings time series (official landings, Spain & Morocco; GSAs 1&3). Catch-at-Length data converted to Catch-at-Age data using LFDA. Growth Parameters, average between IEO 2015 and INRH M vector by age using Gislason spreadsheet, average between IEO 2015 and INRH Tuning data Moroccan survey ACOUMED from 2006 to Some years were estimated. Model Settings Several trials with different combination of values for the main parameters and the corresponding sensitivity and retrospective testing, led the group to choose the following values: Ages 0 to 3+ (Ag 3 is a Plus Group) Fbar has been set 1-2 R-age was set at 1 and q-at age 2 S.E. of the mean to which the estimates are shrunk 2 (Shk.yrs) Minimum standard error for population estimates derived from each fleet = 3 (fse) r age q age Shk.ages Shk.yrs fse

31 Results (XSA sardine GSAs 01and 03) Figure 34 shows that In Alboran sea, the exploited stock is mostly composed by ages 1 and 2 when data from Gsa 01 and GSA 03 are summed up. Figure 34. Age structure of sardine in GSA01&03 Recruitment is different from one year to another with decline in 2010 and a peak in It shows decrease in the last three years. Spawning Stock Biomass (SSB) is quite similar to recruitment. It shows decreasing trend since Average fishing mortality in ages 1-2, (Fbar 1-2) fluctuates between 0.15 and It s quite stable in the last four years in low level. Figure 35 summarises these trends as provided by XSA outputs and table 10 the values of reference points. 28

32 Figure 35: main results obtained by XSA model. Table 10. Reference points obtained from XSA with survey indices as tuning data Reference points XSA F Fcur 0.22 F/F E 0.22 The exploitation rate E = Fbar(1-2) / Z is below 0.4 (threshold suggested as a biological reference point for small pelagic (Patterson, 1992). Also, the ratio F/F0.1 is below 1. So, the sardine stock is considered sustainably exploited. As the model was very unstable responding very differently to the changes of parameters, the Study Group decided to use CPUEs instead of abundance indices from 29

33 surveys, provided that the surveys series had some empty years and that the estimates could be not very reliable. Model XSA Tuned with CPUE Summary of Input data and Parameters Landings time series (official landings, Spain & Morocco; GSAs 1&3). Catch-at-Length data converted to Catch-at-Age data using LFDA. Growth Parameters, average between IEO 2015 and INRH M vector by age using Gislason spreadsheet, average between IEO 2015 and INRH Tuning data the sum of CPUE Morocco and Spain from 2004 to Table 11. Abundances index is the CPUE by age. Age We used the catch numbers by age divided by effort (number of trips) for GSA01&03 combined from 2004 to Summary of model Settings Ages 0 to 3+ (Ag 3 is a Plus Group) Fbar has been set 1-2 R-age was set at 0 and q-at age 3 S.E. of the mean to which the estimates are shrunk 2 (Shk.yrs) Minimum standard error for population estimates derived from each fleet = 2.5 (fse) Results r age q age Shk.ages Shk.yrs fse Recruitment is quite stable since 2007 with a peak in Spawning Stock Biomass (SSB) is quite similar to recruitment. It shows decrease trend since Average fishing mortality in ages 1-2, (Fbar 1-2) is variable and fluctuates between 0.2 and 0.5. Figure 36 summarises these results and table 12 shows the values of reference points. Table 12 Reference points obtained from XSA with CPUE as tuning data Reference points XSA F Fcur 0.32 F/F E 0.29 The exploitation rate E = Fbar(1-2) / Z is below 0.4 (threshold suggested as a biological reference point for small pelagic (Patterson, 1992). Also, the ratio F/F0.1 is below 1. So, 30

34 the sardine stock is considered sustainably exploited. Figure 36: main results obtained by XSA model with CPUE as tuning data. Model run with non-equilibrium surplus production model (BioDyn) The modelig approach uses four basic parameters: Carring capacity (or Virgin Biomass) K, population intrinsic growth rate r, initial depletion BI/K (starting biomass relative to K) and catchability q (fixed). Environmental effect is also estimated if included in the model. Given the best parameter estimates, the model calculates the overall MSY, BMSY and FMSY reference points. Derived reference points were also evaluated: BCur/BMSY, indicating whether the estimated stock biomass, in any given year, is above or below the biomass producing the MSY, and FCur/FSYCur (the ratio between the fishing effort in the last year of the data series and the effort that would have produced the sustainable yield at the biomass levels estimated in the same year), indicating whether the estimated fishing mortality, in any given year, is above or below the fishing mortality producing the sustainable (in relation to natural production) yield in that year. Several other trials were carried out to incorporate data from Algeria. The first of these trials was a model run of a production model BioDyn with the series of catch data from the three countries. Six scenarios by using one or two data series were tested which initial settings are summarised below. 31

35 Senario 01: GSA04 Landings time series (official landings from the two ports of Alboran in Algeria area GSA 04). Abundance index: CPUE (Kg/Fishing day). Carrying capacity (k ) and Population intrinsic growth rate (r). Senario 02: GSA01 Landings time series from 2002 to 2016 (official landings from Spain). Abundance index: CPUE (Kg/Fishing day). Carrying capacity (k ) and Population intrinsic growth rate (r). Senario 03: GSA03 Landings time series from 2005 to 2016 (official landings from Morocco). Abundance index: Morocco Surveys index (with no data for 2009, 2010 and 2013). Carrying capacity (k ) and Population intrinsic growth rate (r). Senario 04: GSA03-04 Landings time series from 2005 to 2016 (official landings from Morocco and extreme Western part of Algeria). Abundance index: Morocco Surveys index (with no data for 2009, 2010 and 2013). Carrying capacity (k ) and Population intrinsic growth rate (r). Senario 05: GSA01-03 Landings time series from 2005 to 2016 (official landings from Spain and Morocco). Abundance index :Morocco Surveys index(with no data for 2009, 2010 and 2013). Carrying capacity (k ) and Population intrinsic growth rate (r). Senario 06: GSA01-03 & 04 Landings time series (official landings from Spain, Morocco and Algeria; GSAs 01-03&04). Abundance index: Morocco Surveys Index from 2005 to 2015 (with no data for 2009, 2010 and 2013). Carrying capacity (k ) and Population intrinsic growth rate (r). Table 13 shows the different results obtained by the application of the BioDyn to sardine catches from Alboran Sea. 32

36 Table 13. Biodyn results for the different scenarios tested. Scenario1 Scenario2 Scenario3 Scenario4 Scenario5 Scenario6 GSA04 GSA01 GSA03 GSA03-04 GSA01-03 GSA Rpearsonindex Rsquare Fcur F FMSY Fcur/F Fcur/FMSY B/BMSY Diagnose of stock status GSA04: Overexploited and in overexploitation (Fcur/F0.1=2.098). Fcurrent (0.15) is higher than the F0.1 reference point (0.07). Bcurrent is below BMSY (Bcurr/BMSY=0.279). GSA01: Overexploited and in overexploitation. Fcurrent is over F0.1 (Fcur/F0.1=1.201). Fcurrent is over Fmsy (Fcur/Fmsy=1.081). Bcurrent is below BMSY (Bcurr/BMSY=0.740). GSA03: Overexploited with a low fishing mortality. Fcurrent is below F0.1 (Fcur/F0.1=0.853). Fcurrent is below Fmsy (Fcur/Fmsy=0.768). Bcurrent is below BMSY (Bcurr/BMSY=0.654). GSA03-04: Overexploited with a low fishing mortality. Fcurrent is below F0.1 (Fcur/F0.1=0.733). Fcurrent is below Fmsy (Fcur/Fmsy=0.660). Bcurrent is below BMSY (Bcurr/BMSY=0.673). GSA01-03: Overexploited with a low fishing mortality. Fcurrent is below F0.1 (Fcur/F0.1=0.775). Fcurrent is below Fmsy (Fcur/Fmsy=0.698). Bcurrent is below BMSY (Bcurr/BMSY=0.716). GSA : Overexploited with a low fishing mortality. Fcurrent is below F0.1 (Fcur/F0.1=0.737). Fcurrent is below Fmsy (Fcur/Fmsy=0.663). Bcurrent is below BMSY (Bcurr/BMSY=0.704). Model performance: The value of R2 fluctuates between 0.04 to It was considered quite poor. The goodness of fit obtained using the surplus production modelling approach is unsatisfactory (Rpearson Index is very low for all scenarios). Pearson linear regression coefficient will not detect a non-linear relation, but will measure how closely the predicted abundance indices follow the observed ones. The results based on the implementation of a non-equilibrium logistic surplus production model, are inconsistent. The predicted biomass curve does not match the acoustic biomass curve and Rpearson is very low. We can consider this assessment as a test only. 33

37 Model run with VPA (VIT) Summary of Input data and Parameters The sardine stock in the Alboran sea was also assessed using a VPA model based on VIT software (Jordi Lleonart and Jordi Salat,1992; updated in 2011). VIT was applied on catch numbers structured by age for the only year that the three countries have in common: year 2016 in Algeria, Morocco and Spain combined. The terminal fishing mortality value chosen for starting the calculations was Fterm = 0.5 and after several trials, it was set at 0.3 Catch data in numbers by age were used as presented in Table 14 and graphically in figure 37 showing that in GSA01, the purse seine fleet targets mainly the age class 0. In GSA03, GSA04 and in the combined GSAs, the most important age class is the age class 1. Table 14: Catch-at-age in numbers for the three GSAs separately and combined Age class GSA01 GSA03 GSA04 GSA01+GSA03+GSA Figure 37: Age composition of landings in the different GSAs and combined. The size structure used for estimation the growth parameters and the length weight relationship in GSA04 were collected monthly in the two ports of west of Algeria Ghazaouet and Beni-Saf in Table 15 shows the values of these parameters as 34

38 estimated by the three countries and last column represents the average, which were finally used to run the VPA. Table 15. Growth parameters and length-weight relationship for sardine in the three GSAs and the average used in the model. Parameters GSA01 GSA03 GSA04 GSA01_GSA03 and GSA04 (avg.) L K t a b Source IEO INRH CNRDPA Average Landings of sardine and fishing effort of purse seiners are from the official data. The biological and the landings data used are those of the year 2016 of GSA01, GSA03 and GSA04. Results VIT (sardine pseudocohort year 2016) Figure 38 shows the catch in numbers of sardine as estimated by VIT. In the GSA01, the purse seine fleet targets mainly the age class 0. In the GSA03, GSA04 and in the combined GSAs, the composition of the catches in number by age class shows that the most important age class is the age class 1. Figure 38: Age structure of the stock as estimated by VIT 35