BALAENOPTERA EDENI (CETACEA, BALAENOPTERI DAE) SIGHTINGS AND WATER TEMPERATURE IN SOUTHERN BAJA-CALIFORNIA, MEXICO

From June 1988 to July 1991, 143 cetacean boat surveys were conducted at Bahia de La Pat, B.C.S. to elucidate the relation between B. edeni 's sighting frequency, aid seasonal and annual sea surface temperature (SST). SST showed significant seasonal and annual changes respectivel y due to the periodic entrance of tropical water masses to the area, a nd the influx of oceanographic phenomena like El Nino and La Nina. Suc h events carry associated changes in productivity and food availabilit y at the corresponding time scales. In contrast, B. edeni 's sighting frequency did not showed correspondence to such SST seasonal or annual changes. It was evident that B. edeni 's relative abundance changed n otably only during specific oceanographic settings derived from the in teraction of annual and seasonal conditions. The results do not suppor t B. edeni 's warm water affinity, nor the species exodus out of Bahia de La Pat during the winter. According to these and other evidences, the proposed winter emigration of such population out of the Gulf of C alifornia seems improbable.