Relative Abundance

Relative AbundanceAre there really less sharks in Costa Rican waters? One way to know is to compare relative abundance of sharks in the fishery throughout time.  Unfortunately, long term reliable information on shark relative abundance in the region is largely unknown. Since 1999, PRETOMA has developed an observer program on board commercial longliners from Playas del Coco, Costa Rica, belonging to Papagayo Seafoods S.A.,

Our research shows a dramatic 60% decline in shark relative abundance in the longline fishery from 1991 to 2001.  From 2001 to 2003 no further decline was detected, because of which we concluded that in the Exclusive Economic Zone of Costa Rica sharks had hit rock bottom.

Preliminary Results of our studies:

Arauz, R., Y. Cohen, J. Ballestero, A. Bolaños, M. Pérez. 2004. Decline of Shark Populations in the Exclusive Economic Zone of Costa Rica. International Symposium on Marine Biological Indicators for Fisheries Management. UNESCO, FAO. Paris , France . March, 2004.

Randall Arauz, Andrés López , Jorge Ballestero & Allan Bolaños. 2006. Estimación de la abundancia relativa de tiburones en la Zona Económica Exclusiva de Costa Rica a partir de observadores a bordo de la flota de palangre de Playas del Coco, Guanacaste, Costa Rica.

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