1. GFCM-SAC SubCommittee on Stock Assessment (SCSA) Izmir, 22-26 September 2008 ANCHOVY AND SARDINE STOCK ASSESSMENT IN THE GSA 17: 1975-2007 Santojanni A. 1a, Cingolani N. 1a, Donato F. 1a, Colella S. 1a, Berlardinelli A. 1a, Giannetti G. 1a, Leonori I. 1b, Sinovcic G. 2, Marceta B. 3 1a CNR-ISMAR-SPM, Fish Population Dynamics Unit, Ancona (Italy) 1b CNR-ISMAR-SPM, Marine Acoustics Unit, Ancona (Italy) 2 Institute of Oceanography and Fisheries, Split (Croatia) 3 Fisheries Research Institute of Slovenia, Ljubljana (Slovenia)

2. Anchovy (Engraulis encrasicolus) Sardine (Sardina pilchardus)

3. Mid-water trawlers Italy 2007: about 60 pairs Purse seiners attracting fish by light Italy 2007: 40-50 vessels (including “small” and “high” tonnage) Fishery Mid-water trawlers Purse seiners

4. Data collection since 1975 still ongoing: - catches - fishing effort - length, weight of fish - age (otolith readings) Hauls sampled by the observer on board of Italian fishing vessels Santojanni et al. (2005) - Scientia Marina

5. Geo-referenced small pelagic catch per haul collected by means of electronic logbooks on board of fishing vessels

6. Virtual Population Analysis (VPA) based on Laurec-Shepherd tuning on abundance index derived from echo-survey. Software: Darby C.D., Flatman S. 1994. Virtual Population Analysis: version 3.1 (Windows/Dos) user guide. Information Technology Series, MAFF Directorate of Fisheries Research, Lowestoft, 1: 85 pp. Structure of the data used: Split-year data were used assuming the first of June as the birth date of anchovy. Calendar-year data were used for sardine.

7. Anchovy total catch Sardine total catch

8. Age frequency distribution of the total catch

9. Abundance at sea from echo-survey Sardine Anchovy

10. Natural mortality rate M Anchovy M = 0.6 and M = 0.8 on the basis of - values in the literature - the highest values of life span in our data are 4, 5, 6 years - precautionary approach for M = 0.6 Sardine M = 0.5 on the basis of - values in the literature - the highest values of life span in our data are 10, 11, 12 years

11. Anchovy: M = 0.54 and M = 0.81 were reported for the Catalan Sea by Pertierra and Lleonart (1996). Sardine: M = 0.5 was obtained in the Adriatic Sea by Sinovcic (1986). Values of M from 0.29 to 0.62 were reported for the Catalan Sea by Pertierra and Perrotta (1993). The criterion to select M taking into account the inverse relationship between Z and longevity was adopted for small pelagics by other authors. As reported in a recent GLOBEC report (Barange, 2001), Pacific sardine (Sardinops sagax) is usually assumed to have a relatively low annual natural mortality rate, M = 0.4, and a lifespan of about 10 years, whereas for northern anchovy (Engraulis mordax) M = 0.8 is associated to a lifespan of about 4 years. Barange M. (ed.) 2001. Report of the first meeting of the SPACC/IOC study group on the “Use of environmental indices in the management of pelagic fish populations”, 3-5 September 2001, Cape Town, South Africa. GLOBEC Special Contribution, 5, 122 pp. Pertierra J.P., Lleonart J. 1996. NW Mediterranean anchovy fisheries. Scientia Marina, 60 (Suppl. 2): 257-267. Pertierra J.P., Perrotta R.G. 1993. On the population dynamics of sardine, Sardina pilchardus Walbaum, 1792, from the Catalan Sea (northwestern Mediterranean). Scientia Marina, 57: 235-241. Sinovcic G. 1986. Estimation of growth, mortality, production and stock size of sardine, Sardina pilchardus (Walb.), from the middle Adriatic. Acta Adriatica, 27: 67-74. Natural mortality rate M

12. Hoenig’s equation: Ln Z = 1.44 – 0.982 Ln tmax “based largely on data from unexploited stocks”, thus with Z being very close to M. Hoenig J.M. 1983. Empirical use of longevity data to estimate mortality rates. Fishery Bulletin, 82: 898-903. Hewitt D.A., Hoenig J.M. 2005. Comparison of two approaches for estimating natural mortality based on longevity. Fishery Bulletin, 103: 433-437. Natural mortality rate M tmax (year)predicted Z 14.22 22.14 31.43 41.08 50.87 60.73 70.62 80.55 90.49 100.44 110.40 120.37 130.34 140.32 150.30 160.28 170.26 180.25 190.23 200.22

13. Natural mortality rate M for sardine R square = 0.786 ParameterValueStandard error Confidence interval at 95% Lower limitHigher limit Linf18.7830.22618.33919.226 k0.3790.0280.3240.435 t0-2.3020.185-2.665-1.939 Santojanni et al. (2008): GSA17, year 2007, EU-DCR M = 1.5 K Jensen A.L. 1996. Beverton and Holt life history invariants result from optimal trade-off of reproduction and survival. Canadian Journal of Fisheries and Aquatic Science, 53: 820-822. Jensen A.L. 2001. Comparison of theoretical derivations, simple linear regressions, multiple linear regression and principal components for analysis of fish mortality, growth and environmental temperature data. Environmetrics, 12: 591-598. M = 0.57 with 0.38 [Santojanni et al. (2008), otoliths, fitting] M = 0.69 with 0.46 [Sinovcic (1986), otoliths, Linf and k estimated by Gulland-Holt plot]

14. F/Z = 0.4 = > F = 2/3 M Patterson K. 1992. Fisheries for small pelagic species: an empirical approach to management targets. Review of Fish Biology and Fisheries, 2: 321-338.

16. Anchovy: mid-year stock biomass estimated by VPA

17. Anchovy: comparison between VPA and echo-survey

18. Anchovy: results from VPA with M = 0.6 Total catch (t)Stock biomass (t)Ratio Average 1976-2007278901221090.23 Average 2005-200742614210452*0.20 Fishing mortality rate F Unweighted average of F for age 0-3 Average 1976-2007 0.32 Average 2005-2007 0.24 Weighted average of F for age 0-4 Average 1976-2007 0.22 Average 2005-2007 0.19 *182955 with modified age distribution in the t.f.

19. Anchovy: exploitation rate from VPA with M = 0.6 Average 1976-2007 of F/Z (F0-3 unweighted): 0.34 Average 2005-2007 of F/Z (F0-3 unweighted): 0.28 Average 1976-2007 of F/Z (F0-4 weighted): 0.26 Average 2005-2007 of F/Z (F0-4 weighted): 0.24

20. Year n+1 specified near the data points Anchovy stock-recruitment relationship (derived from VPA with M = 0.6)

21. Sardine: mid-year stock biomass estimated by VPA

22. Sardine: comparison between VPA and echo-survey

23. Sardine: results from VPA Total catch (t)Stock biomass (t)Ratio Average 1975-2007444394443090.10 Average 2005-200717489909280.19 Fishing mortality rate F Unweighted average of F for age 0-5 Average 1975-2007 0.27 Average 2005-2007 0.48 Weighted average of F for age 0-6 Average 1975-2007 0.12 Average 2005-2007 0.17

24. Sardine: exploitation rate from VPA Average 1975-2007 of F/Z (F0-5 unweighted): 0.32 Average 2005-2007 of F/Z (F0-5 unweighted): 0.48 Average 1975-2007 of F/Z (F0-6 weighted): 0.19 Average 2005-2007 of F/Z (F0-6 weighted): 0.25

25. Sardine stock-recruitment relationship (derived from VPA) Year n+1 specified near the data points

26. Simulations of anchovy stock biomass and total catch for the period 2007-2012 from ISMAR report to Italian Ministry N a+1, t+1 = N a, t exp( –(F a + M) ) C a, t = [ F a / (F a + M) ] [ 1 – exp( –(F a + M) ) ] N a, t M = 0.6 F a : the level F is the average 1999-2006. Three scenarios of recruitment: “high”, “low”, “mixed”.

27. N a+1, t+1 = N a, t exp( –(F a + M) ) C a, t = [ F a / (F a + M) ] [ 1 – exp( –(F a + M) ) ] N a, t Simulations of sardine stock biomass and total catch for the period 2007-2012 from ISMAR report to Italian Ministry M = 0.5 F a : the level F is the average 1999-2006. Three scenarios of recruitment: “high”, “low”, “mixed”.

28. The stock biomass of anchovy dropped at a very low level in 1987. After this collapse, recovery took place, but fluctuations still occurred, in particular in recent years. It should be remembered that strong changes over time are commonly observed in the abundance of small pelagics, in particular anchovies (Jacobson et al., 2001). The recent exploitation rate F/Z was under the Patterson’s threshold 0.4, but on the other hand, an increase was observed in both western and eastern side catches of most recent years: the mentioned average for the period 2005-2007, 42614 tonnes, was quite over the average for the previous years from 1995 to 2004, 27353 tonnes. The stock can be considered as fully exploited. Jacobson L.D., De Oliveira J.A.A., Barange M., Cisneros-Mata M.A., Felix-Uraga R., Hunter J.R., Kim J.Y., Matsuura Y., Niquen M., Porteiro C., Rothschild B., Sanchez R.P., Serra R., Uriarte A., Wada T. 2001. Surplus production, variability, and climate change in the great sardine and anchovy fisheries. Canadian Journal of Fisheries and Aquatic Science, 58(9): 1891-1903. Management advice for both species

29. The most recent values of the exploitation rate F/Z of sardine stock, obtained using unweighted F 0-5, were higher than the Patterson’s threshold 0.4: the average for the period 2005-2007 was equal to 0.48 (0.32 for the whole period). Moreover, a strong decline of stock biomass occurred after the peak in the first half of 1980s; this declines was continuous till the end of 1990s: then, biomass was quite stable around values slightly lower than 100000 tonnes, which corresponded to the lowest abundances of the time series. The stock can be considered as overexploited. Management advice for both species

30. It should be noted that Adriatic small pelagic fishery is multispecies and effort on anchovy cannot be separated from effort on sardine, so that most of the management decisions should be taken considering both species. In conclusion, it is recommended not to increase the fishing effort: such an increase would be particularly unwise for sardine. Management advice for both species