The environmentalist group Sea Shepherd said Thursday that it found the body of what appeared to be a vaquita porpoise, one of perhaps only 10 that remain in the world.
The group said the remains were too badly decomposed for immediate identification and had been turned over to authorities for further study.
Two Sea Shepherd patrol boats found the animal in a net Tuesday in the Gulf of California, the only place the critically endangered tiny porpoises live. The group patrols the gulf, also known as the Sea of Cortez, removing illegal fishing nets. The vaquitas get caught in nets set illegally for totoaba, a fish whose swim bladder is considered a delicacy in China.
In a report issued earlier this week, an international commission of experts estimated only six to 22 vaquitas remain alive.
The lower figure was the number of vaquitas actually seen on the surface during a trip by researchers last fall. The higher estimate was the number of the animals that may have been heard over a system of floating acoustic monitors making distinctive, dolphin-like "clicks."
The commission said the most likely number of remaining vaquitas was somewhere around 10.
And the vaquitas are concentrated in an increasingly small area of about 15 miles by 11 miles, its report said.
"The few remaining vaquitas inhabit a very small area, approximately 24 by 12 kilometers, most of which lies within the Vaquita Refuge. However, high levels of illegal fishing for totoaba occur in this area," the report said.
Defending the vaquitas in the small area should not be "an impossible task, as the area to be protected is not large," the report added.
But Sea Shepherd's vessels have come under increasing harassment and attacks in the gulf in recent months, and the totoaba season—in which the big fish gather to breed—will reach its peak between now and May.
The boldness of illegal fishermen, the small number of remaining vaquitas and the inability of the Mexican navy and authorities to stop poaching has raised alarms among environmentalists, who fear the marine mammal could go extinct soon.
"Reports from the region suggest that the illegal fishery is growing, and there have been several recent episodes of violence by illegal fishermen directed at net removal vessels and their crews, legal fishermen, and even the Mexican Navy," the commission's report said. "These events illustrate the continued failure of enforcement efforts and the lack of respect for Mexican law by illegal fishermen."
In a last-stand bid to save the vaquita, the commission urged the Mexican government to provide 24-hour surveillance and patrols of the small remaining habitat area, and "take all necessary measures to protect net removal teams."
"There is only the tiniest sliver of hope remaining for the vaquita," said Kate O'Connell, a marine wildlife consultant with the Animal Welfare Institute. "Mexico must act decisively to ensure that all gillnet fishing is brought to an end throughout the upper gulf."
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