NOTE Zavala-Gonzalez and Mellink: Entanglement of California sea lions in fishing gear 
183 
bage dump. When a fisherman finds a lost drifting 
net at sea, he takes it for his own use. Unlike other 
areas of the world (Croxall et al., 1990) and the south- 
ern Gulf of California (Harcourt et al., 1994), the cen- 
tral-northern portion of the Gulf of California did not 
provide evidence of sea lions entangled in nonfishing 
plastic debris. 
Sea lion conservation 
In addition to accidental entanglements reported 
here, there is a deliberate (although illegal) killing 
of sea lions in the region for baiting shark longlines. 
At Isla San Pedro Martir, Thomson and Mesnick 5 
found 14 sea lions entangled in a gill net in a cave 
about 15-20 m from a breeding site, in July 1993. 
They concluded that the net had been set to inten- 
tionally capture sea lions. In December 1993, about 
20 sea lions were captured in a gill net in San Pedro 
Nolasco (El Imparcial, Hermosillo, Sonora, 25 De- 
cember 1993). The fishermen involved argued that 
the capture had been accidental, resulting from their 
lack of expertise. In addition to their intentional cap- 
ture, sea lions are sometimes shot with firearms be- 
cause fishermen believe that they interfere with fish- 
ing gear (Belgado-Estrella et al., 1994). 
Our data were limited to a single season in each 
year of a 5-yr span and did not include animals that 
died without us having seen them on the islands. 
However, according to our assessment, the current 
entanglements rate of 0.49% does not seem to pose a 
threat to the conservation of California sea lions in 
the central-northern Gulf of California. We believe, 
however, that entanglement should be routinely 
monitored and studied in further detail. 
Acknowledgments 
Maria del Carmen Garcia, Elisa Peresbarbosa, 
Leonardo Inclan, Maria Concepcion Garcia, Jaime 
Luevano, Martin Escoto, Luis Bourillon, Maria de la 
Soledad Tordecillas, Sarah Mesnick, Carlos Godinez, 
Dulce Maria Broussett, and several students from 
the Laboratorio de Mamiferos Marinos, Facultad de 
Ciencias, Universidad Nacional Autonoma de Mexico, 
assisted with field work. Oscar Sosa, Gregory 
Hamman, Fred Julian, Mark Lowry, and Tim 
Gerrodette provided editorial assistance. All cruises 
and surveys were carried out with the support of the 
5 Thomson, D. A., and S. L. Mesnick. 1993. Biodiversity of the 
marine fauna around islands in the Gulf of California. Unpubl. 
report. Department of Ecology and Evolutionary Biology, Univ. 
Arizona, Tucson, AR. 
Armada de Mexico (6ta Zona Naval), to which we 
are greatly in debt. Consejo Nacional de Ciencia y 
Tecnologia (Mexico) supported A. Zavala with an aca- 
demic scholarship and partially supported this 
project through a grant to E. Mellink. The Oficina 
Federal de Pesca in Baja California kindly provided 
fishing records for Bahia de los Angeles. All work 
was carried out under permits from the Direccion 
General de Aprovechamiento Ecologico de los 
Recursos Naturales, Institute Nacional de Ecologia. 
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