Vaquita – Last Chance for the Desert Porpoise

The science is complete and the verdict is in. In order to save the vaquita porpoise, the world’s smallest cetacean, the fishing gear that entangles and drowns them must come out of the water.

At the time of discovery, vaquita were thought to have numbered in the low thousands. But every year, 20 to 30 vaquitas get caught in gillnets and drown. The population has dwindled to 250 at best.

Vaquita are shy as well as rare, it has not readily disclosed its secrets to scientists. What little is known does not bode well for its future. The combination of low numbers, late maturity, low birth rate, and low genetic diversity makes the vaquita vulnerable to extinction in the very near future.

Scientists have worked hard to determine the population status of the animal through the years using boat-based surveys and bycatch estimates. This data is used to recommend conservation and management measures to the authorities. However to date, none of these measures have made any significant difference and the vaquita continues to decline.

Dr. Lorenzo Rojas-Bracho is a Mexican biologist and Vaquita expert from the Instituto Nacional de Ecologıa (INE), Ensenada. In 1997, it was estimated that 567 vaquitas remained. Data collected from observers placed on fishing boats indicated about 78 were being taken as bycatch every year. This figure probably dropped as the population declined. Yet fishing effort doubled from 500 in 1993 to 1,000 in 2007. The number of fishing trips also increased from 1358 in 1993 to 15,000 today.

Using a model that tracks birth and death rates and fishing activity, Dr. Jaramillo-Legorreta and other scientists came up with the current estimate of 250. Because the little porpoises are difficult to spot in the murky waters they frequent, the best way to find them is with acoustic devices, the basis of the most recent expedition.

In October 2008 an international expedition marked the beginning of an all out, last-ditch effort to save the little known vaquita. With so few animals remaining, time is critical. Vaquitas are so timid that until this survey, they had only been seen at long distances (a sighting at 900 meters is considered close) and never captured on film alive.

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“The situation is dire,”

says Dr. Barbara Taylor of the NOAA Fisheries, Southwest Fisheries Science Center in San Diego, California, chief U.S. scientist on the Vaquita Expedition 2008.

“The vaquita has only a few years left before it goes the way of the baiji…The nets have to come out of the water forever,”

says Taylor. “That is the only way to save the vaquita. It is a huge challenge and an enforcement nightmare, but [it's] the only way.”Vaquita increase naturally by 4% a year. The bycatch rate is estimated at 13.5%.”

Scientists say 50 animals is the estimated minimum number of vaquita needed to maintain a reproductively fit population. Any lower than this means inbreeding would occur. The estimated time to this threshold if nothing changes is two years.

However, fishing, specifically shrimp fishing, supports the local communities who supply shrimp (blue shrimp) markets in the US. Ironically 97% of local fishers will never see or catch a vaquita, and are understandably skeptical about the scale of the problem and the impact any reduction in fishing may have on their livelihoods and families.