Vaquita.tv

Although all marine mammals are susceptible to gillnet entanglement (Perrin et al. 1994), porpoises, including vaquita, are particularly vulnerable (Jefferson and Curry 1994). The first reports of incidental catch of vaquitas in totoaba nets came from Norris and Prescott (1961), and the problem of fisheries bycatch was acknowledged by every author writing about the species’ status since that time. Vidal et al. (1994) documented 128 vaquitas caught in gillnet fisheries from March 1985 through February 1992, of which 65 percent were killed in gillnets set for totoaba.

A minimum of 15 vaquitas died from early 1993 to early 1994 in nets set by fishermen from just
one village, El Golfo de Santa Clara (D’Agrosa et al.1995). These first minimum estimates of vaquita
bycatch were presented to the small cetacean subcommittee of the International Whaling Commission in 1994, and that subcommittee expressed “extreme concern over the status of this species” and recommended that “immediate action be taken to eliminate
incidental catches in all fisheries” (International Whaling Commission 1995).

The only effort-corrected study to estimate vaquita incidental catch was that of D’Agrosa et al. 2000). Their study used fisherman interviews and on-board observers to quantify the bycatch of vaquita per fi shing trip in each of five types of gillnets from January 1993 to January 1994. They extrapolated their bycatch rate to the total estimated number of trips from El Golfo de Santa Clara to be 39 vaquitas/year (95 percent confidence interval = 14–93; D’Agrosa et al. 2000). When they
extrapolated mortality rates to the estimated number of fishing trips from neighboring San Felipe, the estimate of total annual bycatch increased to 78–168 per year.

D’Agrosa et al. (2000) concluded that these bycatch rates were unsustainable.

Although fi shermen would no longer be willing to cooperate in such a voluntary study of vaquita bycatch, there is continued evidence of bycatch in fishing operations. From 1995 to 2004, 22 vaquita deaths were reported by fishermen and government field personnel, and 11 carcasses were recovered (Rojas-Bracho and Campoy 2004).

Other Risk Factors

Although fishery bycatch has been identified as the greatest risk factor for vaquita survival, other potential risk factors have been identified and reviewed.

Rojas-Bracho and Taylor (1999) examined three risk factors (pollutants, loss of Colorado River input, and genetic inbreeding) and found that none would appreciably increase the risk of extinction and none would prevent the recovery of vaquita.

Source, excerpt from:

Barlow, J., L. Rojas-Bracho, C. Muñoz-Piña, and S. Mesnick. 2010. Conservation of the vaquita (Phocoena sinus) in the northern Gulf of California, Mexico. Chapter 15 in: R. Q. Grafton, R. Hilborn, D. Squires, M. Tait, and M. Williams (eds.) Handbook of Marine Fisheries Conservation and Management. Oxford University Press, New York. 770pp.