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, Voutes, Iraklion, Greece GFCM – Izmir 2008 Stock assessment of the Aegean Sea (GSA 22) Anchovy and Sardine stock by Integrated Catch at age analysis (ICA)

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

The Fishery Purse seine fleet Purse seine fleet No purse seines Gross Tonnage (GT*) Horse Power (kW) Mean fleet age Average length Greece GFCM – Izmir2008 GFCM – Izmir 2008 >95% responsible for anchovy and sardine catches in Greek waters

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

Data used Purse seine fishery in North Aegean Sea (main fishing grounds for anchovy and sardine in Aegean Sea) Purse seine fishery in North Aegean Sea (main fishing grounds for anchovy and sardine in Aegean Sea) Annual anchovy and sardine landings Annual anchovy and sardine landings   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 GFCM – Izmir2008 GFCM – Izmir 2008

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

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 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) 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) Reference age for the fishery age group 2 (fully exploited & fully recruited) GFCM – Izmir2008 GFCM – Izmir 2008

Weighting factors regarding catches Ages 0 and 4 were downweighted (0.01), considered marginal in terms of their percentage in the catch (< 5% and 1% respectively) 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 Age 3 was downweighted (0.3) represented 6% in the catch Six years separable constrain Six years separable constrain Reference age for the fishery age group 2 (fully exploited & fully recruited) Reference age for the fishery age group 2 (fully exploited & fully recruited) Mean F for ages 1 to 3+ was estimated Mean F for ages 1 to 3+ was estimated GFCM – Izmir2008 GFCM – Izmir 2008

Total anchovy landings R 2 = Year Catches (t) GFCM – Izmir2008 GFCM – Izmir 2008 Anchovy

GFCM – Izmir2008 GFCM – Izmir 2008 Sardine

Tuning indices (fishery independent surveys) GFCM – Izmir2008 GFCM – Izmir 2008 Total Biomass (acoustics) Total Biomass (acoustics) Stock Spawning biomass (DEPM) Stock Spawning biomass (DEPM) Anchovy

GFCM – Izmir2008 GFCM – Izmir 2008 Tuning indices (fishery independent surveys) Total Biomass (acoustics) Total Biomass (acoustics) Sardine

Population status GFCM – Izmir2008 GFCM – Izmir 2008 Major component of the stock: 1-year-old and 2-year- old fish

Length frequency distribution… 2 sub-areas: 2 sub-areas: East area (Thracian Sea and Strymonikos Gulf) East area (Thracian Sea and Strymonikos Gulf) Shift towards smaller length classes in 2005 & 2006 Shift towards smaller length classes in 2005 & 2006 West area (Thermaikos and Evoikos Gulfs) West area (Thermaikos and Evoikos Gulfs) Shift towards smaller length classes in 2005 & 2006 Shift towards smaller length classes in 2005 & 2006 Anchovy GFCM – Izmir2008 GFCM – Izmir 2008 (population)

Length frequency distribution… Sardine  2 sub-areas:  East area (Thracian Sea and Strymonikos Gulf) Shift towards bigger length classes in 2003 & 2006 Shift towards bigger length classes in 2003 & 2006  West area (Thermaikos and Evoikos Gulfs) Shift towards bigger length classes in 2006 Shift towards bigger length classes in 2006 GFCM – Izmir2008 GFCM – Izmir 2008 (population)

GFCM – Izmir2008 GFCM – Izmir 2008 Anchovy Assessment Model: DEPM Absolute_Acoustic Linear according to WGMHSA 2005 suggestion

GFCM – Izmir2008 GFCM – Izmir 2008 Anchovy Assessment Model results (DEPM Absolute_Acoustic Linear according to WGMHSA 2005 suggestion) Population status

GFCM – Izmir2008 GFCM – Izmir 2008  Fishing mortality remains more or less at the same level  Exploitation rate < 0.4 since 2003

Results Preliminary results because of small time series Preliminary results because of small time series Stock characterized by intermediate abundances, fully exploited, with high fishing mortality rates Stock characterized by intermediate abundances, fully exploited, with high fishing mortality rates Exploitation rate below the empirical level for stock decline (0.4, Patterson 1992). Exploitation rate below the empirical level for stock decline (0.4, Patterson 1992). Signs of recovery regarding E, SSB and Recruitment in 2006 Signs of recovery regarding E, SSB and Recruitment in 2006 Reference points can only cautionary suggested as Reference points can only cautionary suggested as  TBlim=31800 t (CV=0.109), estimated in  SSBlim=20500 t (CV=0.170), estimated in  SSBpa=30750 t (as SSBlim*1.5) GFCM – Izmir2008 GFCM – Izmir 2008

Sardine Assessment Model: Acoustic Linear

GFCM – Izmir2008 GFCM – Izmir 2008 Population status Sardine Assessment Model results (Acoustic Linear according to WGMHSA 2005 suggestion)

GFCM – Izmir2008 GFCM – Izmir 2008  F age-2 remains more or less at the same level  Mean F 1-3 shows decreasing trend  Exploitation rate > 0.4

GFCM – Izmir2008 GFCM – Izmir 2008Results Preliminary results because of small time series Preliminary results because of small time series Stock characterized by intermediate abundances, fully exploited, with high fishing mortality rates Stock characterized by intermediate abundances, fully exploited, with high fishing mortality rates Exploitation rate above the empirical level for stock decline (0.4, Patterson 1992) Exploitation rate above the empirical level for stock decline (0.4, Patterson 1992) Signs of recovery regarding TB and Recruitment in 2006 Signs of recovery regarding TB and Recruitment in 2006 Reference points can only cautionary suggested as Reference points can only cautionary suggested as  TBlim=13800 t (CV=0.354), estimated in 2004.

Management suggestions Small pelagics abundances and recruitment are highly variable due to environmental conditions Small pelagics abundances and recruitment are highly variable due to environmental conditionsSo, Monitoring through fishery independent surveys Monitoring through fishery independent surveys Not increase fishing effort 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) GFCM – Izmir2008 GFCM – Izmir 2008

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