Risk factors affecting the vaquita (Phocoena sinus)

Despite the vaquita being commonly cited as one of the most endangered mari ne mammals in the world, there is still disagreement over which factors put the species at greatest risk of extinction. This lack of agreement hinders management decisions needed to reduce the risk to the species. To expedite decision-making we consider four major risk factors. Habitat alteration fr om reduced flow of the Colorado River does not currently appear to be a ris k factor because productivity remains high in vaquita habitat. Pollutant lo ads are low and pose low to no risk. Reduced fitness from inbreeding depres sion and loss of genetic variability are unlikely to pose high risk current ly, though risk will increase if vaquitas remain at low abundance over long periods of time. Mortality resulting from fisheries bycatch poses high ris k. Thus, short term management should not be hindered by uncertainty in est imating the risk of these factors, and primary conservation efforts should be directed towards immediate elimination of incidental fishery mortality.