GIANNOULAKI M., SOMARAKIS S., MACHIAS A., SIAPATIS A., PAPACONSTANTINOU C.

1. GFCM – Izmir 2008 Stock assessment of the Aegean Sea (GSA 22) Anchovy and Sardine stock by Integrated Catch at age analysis (ICA) GIANNOULAKI M., SOMARAKIS S., MACHIAS A., SIAPATIS A., PAPACONSTANTINOU C. Hellenic Centre for Marine Research, PO Box 2214, Iraklion 71003, Greece Department of Biology, University of Crete, PO Box 2208, 41409 Voutes, Iraklion, Greece

2. GFCM – Izmir 2008 An Integrated Catch-at-Age analysis • method that standard VPA assessments are tuned with results from fishery independent stock assessment techniques (Patterson & Melvin 1996). • was applied based on commercial catch data (2000-2006) and • tuning indices: the biomass estimates from acoustic surveys and Daily Egg Production Method (DEPM) estimates (2003-2006)

3. GFCM – Izmir2008 The Fishery • Purse seine fleet >95% responsible for anchovy and sardine catches in Greek waters

4. GFCM – Izmir 2008 Technical measures: Fishing practices, fishing seasons & areas, effort, gear regulations • Closed period (mid December – end of February) • Minimum distance from shore 300m or 30m bottom depth • Minimum no of lamps per vessel (6) • Min landing size (anchovy: 9 cm, sardine: 11 cm) • Min mesh size (40 mm for purse seines working daytime, 14 mm for purse seines working nighttime)

5. GFCM – Izmir2008 Data used • Purse seine fishery in North Aegean Sea (main fishing grounds for anchovy and sardine in Aegean Sea) • Annual anchovy and sardine landings • 2000-2006 • HCMR data collection system, several national & EU projects of HCMR & FRI • Data from 2003 onward were collected within the framework of the Greek National Fisheries Data Collection program

6. GFCM – Izmir 2008 Data • Data were collected on a seasonal basis • Measurements: Total length, biological sampling (weight, otoliths: age reading, gonads for maturity estimates) • Age sampling: • separate length and age sampling or • representative age sampling. • Landings were grouped by length classes (1 cm) and applied on a yearly basis to ALK.

7. GFCM – Izmir2008 Biological information used as input for the model: • Maturity-at-age: based on biological samples from commercial and research vessels collected during the spawning season • Natural mortality: fixed parameter over years and ages (M=0.7 anchovy, M=0.8 for sardine, based on acoustic estimates (No ind/ age group) • Reference age for the fishery age group 2 (fully exploited & fully recruited)

8. Weighting factors regarding catches GFCM – Izmir2008 • Ages 0 and 4 were downweighted (0.01), considered marginal in terms of their percentage in the catch (< 5% and 1% respectively) • Age 3 was downweighted (0.3) represented 6% in the catch • Six years separable constrain • Reference age for the fishery age group 2 (fully exploited & fully recruited) • Mean F for ages 1 to 3+ was estimated

9. Total anchovy landings 25000 2 R = 0.8481 20000 15000 Catches (t) 10000 5000 0 2000 2001 2002 2003 2004 2005 2006 Year GFCM – Izmir2008 Anchovy

10. GFCM – Izmir2008 Sardine

11. GFCM – Izmir2008 Tuning indices(fishery independent surveys) • Total Biomass (acoustics) • Stock Spawning biomass (DEPM) Anchovy

12. GFCM – Izmir2008 Tuning indices(fishery independent surveys) • Total Biomass (acoustics) Sardine

13. Population status GFCM – Izmir2008 Major component of the stock: 1-year-old and 2-year-old fish

14. Length frequency distribution… GFCM – Izmir2008 (population) Anchovy • 2 sub-areas: • East area (Thracian Sea and Strymonikos Gulf) • Shift towards smaller length classes in 2005 & 2006 • West area (Thermaikos and Evoikos Gulfs) • Shift towards smaller length classes in 2005 & 2006

15. Length frequency distribution… GFCM – Izmir2008 (population) Sardine • 2 sub-areas: • East area(Thracian Sea and Strymonikos Gulf) • Shift towards bigger length classes in 2003 & 2006 • West area(Thermaikos and Evoikos Gulfs) • Shift towards bigger length classes in 2006

16. Anchovy Assessment Model: DEPM Absolute_Acoustic Linear according to WGMHSA 2005 suggestion GFCM – Izmir2008

17. Anchovy Assessment Model results (DEPM Absolute_Acoustic Linear according to WGMHSA 2005 suggestion) GFCM – Izmir2008 Population status

18. GFCM – Izmir2008 • Fishing mortality remains more or less at the same level • Exploitation rate < 0.4 since 2003

19. GFCM – Izmir2008 Results • Preliminary results because of small time series • Stock characterized by intermediate abundances, fully exploited, with high fishing mortality rates • Exploitation rate belowthe empirical level for stock decline (0.4, Patterson 1992). • Signs of recovery regarding E,SSB and Recruitment in 2006 • Reference points can only cautionary suggested as • TBlim=31800 t (CV=0.109), estimated in 2005. • SSBlim=20500 t (CV=0.170), estimated in 2005. • SSBpa=30750 t (as SSBlim*1.5)

20. GFCM – Izmir2008 Sardine Assessment Model: Acoustic Linear

21. Sardine Assessment Model results (Acoustic Linear according to WGMHSA 2005 suggestion) GFCM – Izmir2008 Population status

22. GFCM – Izmir2008 • Fage-2 remains more or less at the same level • Mean F1-3 shows decreasing trend • Exploitation rate > 0.4

23. Results GFCM – Izmir2008 • Preliminary results because of small time series • Stock characterized by intermediate abundances, fully exploited, with high fishing mortality rates • Exploitation rate abovethe empirical level for stock decline (0.4, Patterson 1992) • Signs of recovery regarding TB and Recruitment in 2006 • Reference points can only cautionary suggested as • TBlim=13800 t (CV=0.354), estimated in 2004.

24. GFCM – Izmir2008 Management suggestions • Small pelagics abundances and recruitment are highly variable due to environmental conditions So, • Monitoring through fishery independent surveys • Not increase fishing effort • Shift of the closed period (present: mid December to end of February) towards the post recruitment period of anchovy (e.g. October to December) or the post recruitment period of sardine (e.g. February to April)

25. Thank you for your attention