Effects of Marine Mammals on the Sport Fishery in Santa Monica Bay, California

Abstract

Marine mammal-sport fishery interactions in Southern California waters are often observed but far less studied than marine mammal interactions with commercial fisheries (Hanan and Read 1989, Beeson and Hanan 1996, NMFS 1997). Older studies (Fiscus and Baines 1968, Miller et al. 1983) show that sea lions rarely interact with fishing activities in and near Santa Monica Bay while, in later investigations, California sea lions (Zalophus californianus) are reported to negatively affect sport fishing (Beeson and Hanan 1996). Previous to our study, no information was reported on interactions between fishermen and other species of marine mammals, except for Miller et al. (1983). The abundance of marine mammals and sport fishermen makes Santa Monica Bay an excellent area to further investigate marine mammal-sport fishery interactions, to compare results with previous findings, and to provide information for future conservation and management decisions linked with the creation of a Marine Protected Area in Santa Monica Bay. The most common marine mammals known to inhabit and feed in the bay year-round include the California sea lion, the bottlenose dolphin (Tursiops truncatus), the short-beaked common dolphin (Delphinus delphis) and the longbeaked common dolphin (D. capensis) (Bearzi 2005a). A survey of sport fishermen was conducted during 1998–1999 to gather general information on the type of interactions existing between marine mammals and fishermen activities and how marine mammals affect sport fishery in Santa Monica Bay. Of 90 interviewed sport fishermen, 30 were selected for the survey in Marina del Rey and Redondo Beach harbors during February–June 2000. The fishermen selected were required to have fished year-round and to have made at least 20 fishing trips per year in Santa Monica Bay (Point Vicente 33u 459 N 118 249 W to Point Dume 33u 599 N 118 489 W, up to 20 km offshore). Further, the fishermen were chosen from both charter boats (n 5 18) and private vessels (n 5 12); this was different from previous investigations where those interviewed were exclusively on charter boats (Miller et al. 1983, Beeson and Hanan 1996). Information about Sport Fishermen and Their Catches Of the selected fishermen, 87% stated they spent 1–3 days per month fishing in the bay and 80% preferred fishing during the summer months (June–August). Most (67%) fished less than 10 km from shore, of which 43% were within 1–5 km and only one fisherman at less than 1 km from shore. In 1998, 38% of the fishermen reported catching mostly ‘‘bass’’ (the term bass is generally used by local fishermen to include any fish species similar to a rockfish) and 36% reported catching mostly yellowtail, Seriola lalandi. In 1999, 47% of the fishermen reported catching ‘‘bass’’ most abundantly while only 13% reported catching yellowtail. Interactions with Marine Mammals All the fishermen observed dolphins in 1998 and 1999. Virtually all (97%) stated that dolphins – generally recognized as ‘‘common dolphins’’ never interfered with their fishing operations; one fisherman reported one Bull. Southern California Acad. Sci. 106(3), 2007, pp. 215–217 E Southern California Academy of Sciences, 2007