Stock identification using otolith microchemistry of Mugil curema in Mar Caribe, Venezuela to contribute to fisheries management.

CALLICÓ FORTUNATO R; AVIGLIANO E; BUITRAGO, JOAQUIN; VOLPEDO A V

Mar del Plata

Congreso; Coastal and Estuarine Research Federation (CERF 2012: The Changing Coastal and Estuarine Environment: A Comparative Approach; 2012

Coastal and Estuarine Research Federation

Nueva Esparta State, which includes the islands of Margarita, Coche and Cubagua, is the third in importance in fish production (10.17%) in Venezuela. The silver mullet (Mugil curema) is the second ichtic resource of artisanal extraction in Venezuela and is the essence of the economy of small communities. In the last years, the use of sagittae otolith microchemistry, has optimized stock discrimination of different commercial species. Trace metals in otoliths come from water and diet; the most studied ones so far are Strontium (Sr) and Barium (Ba). The aim of this work was to identify silver mullet fish stocks in Nueva Esparta state using microchemistry of sagittae otolith; the goal of this work is to contribute to the knowledge on this species population movements and provide helpful information for the management of artisanal fisheries in the area. 110 M. curema adult individuals were captured with gill nets in 7 locations on the coastal region of Nueva Esparta state in July 2011. 21 individuals were obtained in the north of Cubagua island (n=21) and the others in the coastal area of Margarita island: Laguna Punta de Piedras (n=6), El Guamache (n=22), La Isleta (n=14), Manzanillo (n=16), La Guardia (n=22) and Laguna La Restinga (n=11). Simultaneously, water samples were taken to determine the concentration of trace metals. Total length (LT) in cm was measured and otoliths extracted. Determination of Sr and Ba in otoliths was made using inductively coupled plasma optical emission spectroscopy (ICP-OES); and Ca determination was obtained by titration with EDTA. The mean values of  otoliths Element:Ca ratios (Sr:Ca and Ba:Ca) for each group were compared using analysis of variance (ANOVA). Results showed that ratio Sr:Ca of otoliths was in the range of 2.59-3.7 mmol/mol of Ca. The range of ratio Ba:Ca in the otoliths was 12.86-24.33 µmol/mol of Ca. In water samples a gradual decrease of ratio Sr:Ca from southwest of Margarita island (Cubagua island) to northeast (Manzanillo) was found. The ratio range Sr:Ca was 2.76-3.28 mmol/mol. Barium concentration in water was lower than the detection limit of the equipment used for analysis (8 ppb). With this information we discuss the presence of at least two stocks of Mugil curema, one present in the north of Margarita island and other in the south of the same island.