Once upon a time, the world's smallest porpoise, the so-called "panda of the sea," swam wide and free in the Gulf of California. This could be the start of a tragic tale on illegal fishing, animal trade and extinction - if no action is taken.

Despite the Mexican government's efforts to stop decline of the critically endangered vaquita, the situation has become dire: The population has dropped from 200 in 2012 to fewer than 100 in 2014 - and some 60 in late 2015, according to the International Committee for the Recovery of the Vaquita (CIRVA).

Captivity is to be the last resort to keep vaquitas alive. The Mexican government and CIRVA announced plans to try and capture the remaining shy cetaceans, with hopes for a captive breeding program.

But here's the rub: Not a single vaquita has ever been caught alive. And though the "captivity question" - that is, whether captivity is an adequate conservation method - has been long raised, consensus among conservationists has yet to be reached.

Failed protection efforts

Despite governmental efforts to reduce the use of illegal nets and capture ghost nets left drifting in the sea, the vaquita's population has dropped precipitously. Of the approximately 60 members, less than 10 are thought to be breeding females.

Bycatch is the vaquita's number-one enemy. The world's most rare marine mammal continues to get entangled in gillnets used in illegal fishing, aimed at capturing the also endemic totoaba fish - its precious swim bladder is worth tens of thousands of dollars on the Chinese black market.

In the time period from October 10 and December 7 last year, conservation groups including WWF and the Sea Shepherd Conservation Society, together with the Mexican navy, removed more than 100 nets in the upper Gulf of California.

The Mexican government has additionally provided three drones for the conservation campaign - to no avail.

A matter of life or death

The last measure proposed by the government is to capture the few vaquitas remaining and facilitate their reproduction in captivity. With this, scientists face a challenging task - as this would be the first time ever a vaquita would be caught alive.

CIRVA co-chairman Lorenzo Rojas-Bracho is aware of the risk captivity poses for vaquitas - but he believes there are no other options left.

"Capturing them is a very difficult decision. It implies risks, but it won't be rushed," Rojas-Bracho told wire service AFP. "In any sign of stress, we will set them free."

But some conservationists are against the program.

Stephan Lutter, policy advisor for marine protected areas and cetaceans with WWF Germany, believes captivity represents too high a risk for a species with so few individuals left, and animals should rather be recovered in their natural ecosystem.

In spite of few cases where porpoises were occasionally able to produce offspring, captivity has been proven insufficient, Lutter told DW.

"The definition of successful breeding is that they also reproduce in the subsequent generation - which has never happened," he added.

Challenge accepted

As the debate rages, researchers are preparing their action plan. Keeping vaquitas healthy and far from gillnets is the main priority.

With that aim, the international committee is establishing a group of experts in acoustic monitoring, porpoise capture, veterinary medicine and other special expertise to carry out the effort.

"It would involve locating them, capturing them, and putting them in some kind of protective zone," Rojas-Bracho told the media.

Beyond the vaquita's security, experts worry as well about how removing the species from the wild will impact its swimming companion, the totoaba. Removing the delicate vaquita from the equation could result in easing fishing regulations.

Lutter is confident that totoabas, also critically endangered, will remain stable since there is already a strong program in place to protect the species.

However, he does fear monetary struggles for covering the expenses of both controlling illegal fishing, and breeding vaquitas in captivity.

"It's already been very costly to remove gillnets and provide fishermen with alternatives for safe fishing gear," he said.

Vaquita only in fairytales?

Conservationists are warning that the vaquita could disappear by 2022 if further measures are not taken - or if ongoing measures continue failing.

Lutter maintains that there is hope - as long as vaquita are not put into captivity.

"In the light of the huge efforts the government and groups such as WWF are making, there is some hope for recovery of the small population," he said.

"It is still possible to build up the population again even from a very small number," he continued.

Lutter cited the case of Maui dolphins in New Zealand, which numbered as few as 40 individuals some years ago.  Through strong measures against harmful practices, they have been able to recover up to around 100.