The environmentalist group Sea Shepherd said on 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 on 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.”