Spawning stock biomass of the North Western Mediterranean anchovy in 2007 I. Palomera, L. Recasens, P. Libori, I. Alvarez, B. Molí, N. Bahamón Institut de Ciències del Mar (ICM) CSIC. Passeig Marítim, Barcelona, Spain GENERAL FISHERIES COMMISSION FOR THE MEDITERRANEAN SCIENTIFIC ADVISORY COMMITTEE Sub-Committee for Stock Assessment Working Group on Small Pelagic Species Izmir, September 2008

GSA 7 GSA 6 Gulf of Lions Rhône Estuary Ebre River Delta Catalan Sea Gulf of Valencia Cape Creus Cape La Nao FRANCE SPAIN DEPM to evaluate the biomass of the anchovy stock has been applied in North Western Mediterranean Two GSAs are included in the area prospected: GSA6 Gulf of Lions and GSA7 Northern Spain The anchovy stock in the Western part of GSA 7 is shared by the French and the Spanish fishery.

Landings in Spanish ports (Catalan sea) increased from late 80’s until early 90’s and decreased thereafter. The highest catches in the area were obtained during 1993 and This was mainly due to an increase of the fishing effort due to the concentration of vessels coming from another Spanish regions (e.g. Alboran Sea). Since 2005 anchovy landings in the Catalonia ports have decreased below 4000 t (1839 t in 2007). Anchovy landings in the Gulf of Lions increased during the late 80s reaching a maximun in 1997 (10000 t); since then it has slightly been decreasing until nowadays, reaching values similar to those obtained in the early 80s A partial closure (two months per sub-area) of the purse seine fleet during autumn and winter months started in 1993 in Catalan ports. Evolution of the fishery

Biomass evolution: Acoustic estimation Gulf of Lions – GSA 7 Summer cruises IFREMER data (SCSA 2007) Increasing trend that reached its maximum in 2001 ( t). After this year the biomass strongly decreasing to t in 2007 (Liorzou, pers. com.) Northern Spain - GSA 6 Autumn cruises IEO data (SCSA 2007 Although this evaluation is mainly concentrated in recruits, the trend seems to coincide with the stock in the Gulf of Lions, with a maximum value also in 2001 (31279 t) decreasing to 4906 t in 2007 (Giraldez, perss. com.)

DEPM – Anchovy GSAs 6 and

Egg surveyAdult sampling 326 plankton samples 126 CTD profiles 40 adult samples: 16 pelagic trawl (M, P) 24 purse seine (B, T) PARAMETERS P, AR, F, W, S

Egg Production Spawning area Abundance and distribution of anchovy eggs obtained during the sampling cruise MPOCAT07. Points indicated sampling stations and circles relative abundances of eggs millions km millions km EGG PRODUCTION, P 0 – SPAWNING AREA, A All AreaNorthSouth P 0 (eggs/m 2 /day) CV 57, , , z (egg mortality) Range of temperatures at 10 m ( 0 C) P 0 whole area (eggs/day) x (10 12 ) CV Anchovy Eggs June 2007

DEPM Parameters All AreaNorthSouth P 0 (eggs/m 2 / per day) (0.20) (0.26) (0.25) A (km 2 ) W (average female weight in g) (0.04) (0.03) (0.02) F (batch fecundity) (0.11) (0.08) (0.08) S (spawning fraction/day) 0.29 (0.05) 0.29 (0.05) 0.29 (0.05) R (fraction of mature females) 0.58 (0.04) 0.54 (0.04) 0.54 (0.05) BIOMASS (T) (0.23) (0.18) (0.26) Parameter obtained for anchovy spawning biomass estimation through DEPM in the North Westrern Mediteranean during the peack spawning of 2007 and resulting biomass obtained. Between brackets the coefficient of variation of each parameter. ANCHOVY DEPM PARAMETERS 2007

COMPARISON WITH PREVIOUS DEPM ESTIMATES 1993 and North (Gulf of Lions + North Catalan sea) P0P0 (*) A1A South (South Catalan sea + Gulf of Valencia) P0P A1A All Area P0P A1A * Not possible to derive the North data from the available data

Egg Production Positive Area millions millions km km millions millions km km2 Spawning area and Egg Production comparison Anchovy eggs June 2007 June 1994

BIOMASS (t) % Reduction (*) North (Gulf of Lions + North Catalan sea) (0.35) (0.41) (0.23) 34 South (South Catalan sea + Gulf of Valencia) 8422 (0.43) (0.43) 3047 (0.18) 69 All Area (0.30) (0.36) (0.26) 42 COMPARISON WITH PREVIOUS DEPM ESTIMATES 1993 and (*) 2007 Biomass reduction in comparison with the average values of 1993 and 1994

CONCLUSIONS 1.The anchovy spawning biomass in the North Western Mediterranean Sea, GSAs 6 and 7 was estimated by means of the DEPM. Biomass estimate was tons in the whole area, from these t were from the Northern spawning stock and 3050 t f rom the Southern spawning stock. 2.The low biomass estimate in the Southern area in addition to the fact that the spawning area extension is similar to the Northern one, allows us to infer that this year the anchovy population in the Southern area was very widespread and hence less accessible to the fishing vessels. 3.Comparisons of the present results to those obtained in 1993 and 1994 by the same method, indicated an important decrease in anchovy biomass and also in egg production, specially in the southern area. 4.The situation of the Gulf of Lions stock found by the acoustic analysis done by IFREMER also showed a continuous decrease, being an 84% lower nowadays compared to In addition, the results found by IEO acoustic estimates showed a decreasing trend in the recruitment since 2001 with a slight recovery in 2006, that has not been detected in the 2007 landings.

5. These results together with the poor fisheries results for the past years allow us to consider that the anchovy stock in the North Western Mediterranean might be in a critical situation, specially in the southern area. 6. Although it not exist any point of reference on the minimum sustainable biomass for anchovy in the North Western Mediterranean, everything seems to indicate that the stock might be at risk with a reduced reproductive capacity. 7. Moreover, it is unlikely that a small size stock like the present one could have a strong recruitment, mostly if we consider the well documented cases about the quick influence that any environmental variation can have on small pelagic fish populations.

MANAGEMENT RECOMMENDATIONS  To close the anchovy fishery in the GSA 6, at least until the recruitment levels obtained by scientific studies do not reach the same levels as in 2003 (20000 t as Reference level).  Followed with a reduction of the fishing effort, and  To increase the anchovy fishing allowable size to 11 cm.  To establish assessment rules between French and Spanish governments directed to preserve the shared anchovy stocks in the GSA 7 (Gulf of Lions).

THANKS FOR YOUR ATTENTION and THANKS STELIOS FOR THE PRESENTATION