This 1992 photo released by Omar Vidal shows a dead totoaba, top, and a vaquita marina after they were caught in gillnet, set by fishermen to catch totoaba fish in the El Golfo de Santa Clara, in the northern part of Mexico’s Sea of Cortez. Scientists are warning that the population of Mexico’s endangered vaquita marina, the world's smallest porpoise, has fallen to alarmingly low levels and is heading toward extinction soon if drastic measures aren’t taken. The results of a survey by the International Commission for the Recovery of the Vaquita were released Friday, May 13, 2016 by Mexico’s Environment Department. (Omar Vidalvia Associated Press)

MEXICO CITY - The population of Mexico's endangered vaquita marina, the world's smallest porpoise, has fallen to alarmingly low levels and is heading toward extinction soon if drastic measures aren't taken, scientists warned Friday.

According to results of a survey released in the evening by the country's Environment Department, as of December there were probably only about 60 of the shy, elusive creatures left in the upper Gulf of California, the only place where the vaquitas are found.

The vaquitas are threatened primarily by gillnet fishing for the totoaba fish, another endangered species in the area that is hunted for its swim bladder, considered a delicacy in China.

The study was conducted by the International Commission for the Recovery of the Vaquita using a team of boats and acoustic devices to detect their sonar-like squeaks or clicks. One scientist who participated said it was like listening to a room full of people clapping, and then hearing less and less clapping as the population dwindled.

The last such survey found just under 100 vaquitas in 2014. Overall, their numbers are down 92 per cent since 1997.

"We are watching this precious native species disappear before our eyes," said Lorenzo Rojas-Bracho, chair of the commission and the survey's co-chief scientist.

Even since the most recent study was conducted, three vaquitas were found dead during just three weeks in March by the Sea Shepherd Conservation Society, leading some to fear their numbers could be significantly lower.

"Finding three vaquitas in three weeks is finding one dead vaquita per week," Sea Shepherd captain Oona Layolle said. "If we look at the rate the vaquita population has been killed and the intensity of illegal activity at night, there are very likely fewer than 30 vaquita left. If we continue losing the vaquita at this rate it will be extinct by this coming December."

Others offer a slightly less dire outlook but still say the situation is critical.

Omar Vidal of the World Wildlife Fund's Mexico office said he believes there are likely fewer vaquitas remaining than the 60 found by the survey.

"I believe that it is still possible to save the vaquita, but this is clearly our last chance," Vidal said. "The Mexican, U.S. and Chinese governments need to take urgent and co-ordinated action to stop the illegal fishing, trafficking and consumption of totoaba products. In the end, if the vaquita goes extinct it would inevitably be a shared responsibility of the three countries."

Dried totoaba bladders are often smuggled through the United States to China.

Vidal called on the Mexican government to essentially ban all commercial fishing in the upper Gulf of California. At present the Mexican navy and environmental authorities patrol the area, but some legal fishing boats may clandestinely be setting nets for totoaba.

In April 2015, Mexican authorities announced a $70 million plan to ban gillnet fishing in about half of the upper Gulf. The plan promised to compensate fisherman for not using gillnets and offered them alternative, safer nets.

However that has not been effective for reasons ranging from the very high payoff — a totoaba bladder can sell for $5,000 in the United States and double that in Asia — to inefficiency in the compensation program. Some say criminal gangs may be involved in the illicit trade.

Mexican Environment Secretary Rafael Pacchiano said he regretted the death of the three vaquitas found so far this year. He called for strengthening protections for the species and urged fishermen to report illegal activities.

Alejandro Olivera of the Center for Biological Diversity said a large part of the problem is the 800 or more boats legally fishing for corvina in the area. Some totoaba fishermen appear to have hidden among those boats, or some corvina boats set out nets for totoaba as well.

Olivera also said there has been a grossly unequal distribution of the government compensation funds for not setting out gillnets. Most of the 2,700 local fishermen received just $220 to $440 per month while a handful got as much as $63,000, according to documents he obtained through a freedom of information request.

If officials are unable to halt the vaquita's decline, it risks becoming the fifth marine mammal to go extinct in modern times, according to the World Wildlife Foundation.

The Steller's sea cow disappeared in 1768, the Caribbean monk seal in 1952, the Japanese sea lion in 1970 and the Chinese river dolphin in 2006.

While capture and captive breeding remain as a possible last resort, no one has ever succeeded in keeping a vaquita alive in captivity, much less breeding them.

Activists said extinction could also end the kind of shielding effect that the protections for the charismatic porpoises resulted in for the surrounding habitat.

"Once the vaquita is gone, enforcement would probably come to an end," Vidal said. "The remaining marine life — the totoaba, shrimp, corvina, sharks, sea turtles —will follow the same path."

News from © The Associated Press, 2016