Presentation on theme: "GENERAL FISHERIES COMMISSION FOR THE MEDITERRANEAN (GFCM) SCIENTIFIC ADVISORY COMMITTEE (SAC) Sub-Committee of Stock Assessment (SCSA) Working Group on."— Presentation transcript:
GENERAL FISHERIES COMMISSION FOR THE MEDITERRANEAN (GFCM) SCIENTIFIC ADVISORY COMMITTEE (SAC) Sub-Committee of Stock Assessment (SCSA) Working Group on Small Pelagics Izmir, Turkey, 22-26 September, 2008 G.S.A. 16, South of Sicily - Trends in anchovy and sardine populations (1998-2008) I.A.M.C. C.N.R. – Mazara del Vallo (Italy)
Catch-effort data Catch-effort data collection was originated in 1997 through a EU-DGXIV funded study coordinated by I.A.M.C.-C.N.R. This study firstly evidenced the socio-economic importance of small pelagic species in the “South of Sicily” sector of the Sicilian Channel (G.S.A. 16 of General Fisheries Commission for the Mediterranean - FAO).16 15 13
Catch-effort data Catch-effort census data have been collected at Sciacca port since April 1997. Sciacca is the most important base port for the landing of small pelagic species along the southern Sicilian coast. It was estimated to account for about 2/3 of total small pelagic landings in GSA 16. Two fishing gears are operated: purse seine and pelagic pair trawl.16 15 13
Catch-effort data Landings from purse seiners and pelagic pair trawlers are almost exclusively (>90%) composed by sardines (Sardina pilchardus) and anchovies (Engraulis encrasicolus). The main fishing area was located on the southern Sicilian shelf, from Mazara to Licata.16 15 13
Sciacca small pelagic fishery Sciacca small pelagic fishery (purse seiners and pelagic trawlers) is composed by: 15 pairs of pelagic trawlers (Sciacca is the only port along the southern Sicilian coast with this type of fishery); 17 purse seiners from different base ports: 5 Sciacca, 3 Trapani and 9 Terrasini. N.Nome UnitàMatr. 1Nuovo Risorto3PE288 1Nuovo Oriule3PE523 2Maria di Fatima3PE406 2Umberto Luigi3PE417 3Loretta Pulcini3PE412 3Calogero Padre C.3PE625 4San Giuseppe Secondo3PE470 4Valbruna3PE492 5Orizzonte Secondo3PE476 5Pietro Padre Primo3PE564 6Maria Stella del Mare3PE488 6Azzurra3PE592 7Antonino Padre3PE612 7Abramo3PE648 8Freccia dell'Est3PE509 8Angelita3PE606 N.Nome UnitàMatr. 9Nuovo Lealdo3PE604 9Nuovo S. Pietro3PE650 10San Francesco C.3PE550 10Nuova Luigia3PE659 11Sacro Cuore di Gesù3PE623 11Serena3PE646 12Santo Padre3PE622 12Ardito3PE630 13Gaetano Catania3PE602 13Portofino3PE636 14Immacolata Concezione3PE593 14Costantino3PE599 15Pietro il Grande3PE529 15Città di Viareggio3PE590 Pairs of pelagic trawlers:
During the last decade landings (mainly anchovy) have had remarkable interannual fluctuations. * 2008 data updated to June, 30th.
In the same period total fishing effort maintained quite stable, though pelagic trawl tended to replace purse seine.
Acoustics The acoustic surveys were carried out in the Strait of Sicily, on the continental shelf off the southern coast of Sicily, during the summer (June- July) in 1998, 2000, 2002-2003 and 2005-2008, and during the autumn (September-October) in 1999, 2000, 2001 and 2004-2005. Biomass evaluations were carried out by applying a standardised methodology. Applied equipment included: SIMRAD EK 500 two-frequency (38, 120 kHz) split beam echo sounder (EK60 starting from 2005); SIMRAD EK 500 two-frequency (38, 120 kHz) split beam echo sounder (EK60 starting from 2005); pelagic trawl net for experimental hauls with the following characteristics: horizontal opening 13-15 m, vertical opening 6-8 m, mesh size in the cod-end 10 mm; pelagic trawl net for experimental hauls with the following characteristics: horizontal opening 13-15 m, vertical opening 6-8 m, mesh size in the cod-end 10 mm; acoustic monitoring systems of trawl net positioning (SIMRAD ITI). acoustic monitoring systems of trawl net positioning (SIMRAD ITI). Calibration procedures were carried out on board using a standard copper sphere.
Estimated biomasses (tons) by year and species are shown in the following table: Results During the period 1998-2007, both sardine and anchovy populations experienced quite large inter-annual fluctuations. As regards sardine, biomass estimates ranged from 6,000 metric tons in July 2002 to over 38,000 metric tons in July 2005. Anchovy evaluations range from 6,370 metric tons in June 2006 to about 32,000 metric tons in October 2005. Echo-surveySardineAnchovyTotal June 1998 20,0007,10027,100 October 1999 33,70020,20053,900 July 2000 36,37011,00047,370 September 2000 24,80011,05035,850 October 2001 10,05422,95033,004 July 2002 6,00011,50017,500 June 2003 9,5009,20018,710 October 2004 17,9609,82027,780 July 2005 21,21920,72041,921 October 2005 38,79532,13870,933 June 2006 10,2206,37016,590 June 2007 11,0436,72517,768
Sardine population experienced a decreasing trend up to 2002, from 36,000 t in 2000 to just 6,000 t in 2002, with a recovering in the following years up to 2005. Anchovy and sardine exhibit a similar fluctuation pattern during the last years, including the “collapse” in 2006, confirmed by the 2007 estimates. Discussion
Discussion Comparisons between landings and biomass show that acoustic estimates are largely consistent with catch levels recorded in Sciacca port during the year following the evaluation campaigns.
Combining acoustic biomass evaluations and reported landings we obtained the following exploitation rates estimates. Discussion