Influence of purse-seine fisheries on longline fisheries for yellowfin tuna (Thunnus albacares) in the western Indian Ocean

Abstract

An examination is made of the possible impact of purse seine fisheries on the longline fisheries for the Western Indian Ocean yellowfin tuna (Thunnus albacares) stock. Past research works on fisheries interactions are reviewed and then descriptive (spatial and temporal) analyses are attempted for basic fisheries statistics (catch, CPUE and size). It was discovered that the general trends of longline CPUE are more or less constant in the whole purse seine fishing ground before and after purse seining started, while those in the heavy purse seine fishing grounds show a moderate decrease. This moderate decrease is discussed for 2 cases: the long-term situation and the immediate situation.