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Conservation

VaquitaCPR: Trying to save the world’s most endangered marine mammal

Rojas-Bracho L, et al. (2019) A field effort to capture critically endangered vaquitas (Phocoena sinus) for protection from entanglement in illegal gillnets. Endangered Species Research 38:11–27. https://doi.org/10.3354/esr00931

What do you do when the species you’ve been working to save from extinction is down to fewer than 30 individuals? With only thirty vaquita porpoises left in the entire world, despite years of conservation efforts, emergency action needed to be taken. VaquitaCPR (Conservation, Protection, and Recovery) was a project carried out by 90 experts from 9 different countries in October 2017 in an effort to save the world’s smallest and most endangered porpoise.

Vaquitas are rare and cryptic animals that are especially hard to find because they are so small. (Source: http://www.fisheries.noaa.gov/pr/species/mammals/porpoises/vaquita.html)

What happened to the vaquita?

The vaquita, which only grows to about 5 feet long, is native to a small, northern part of Mexico’s Gulf of California and was only first described as a species in the 1950s. Since then, the population has rapidly declined as vaquitas were continually caught as bycatch in a type of fishing net called gillnets. Despite conservation efforts and, in particular, efforts by Mexico’s government to ban gillnets altogether, vaquitas just kept dying. The vaquita, like other marine mammals, plays a vital role in its ecosystem. Porpoises are a top predator, controlling prey species populations, and they circulate valuable nutrients through their waste and, eventually, decomposing bodies. Loss of vaquitas means damage to an entire ecosystem.

The Gulf of California is highlighted in light blue on this map of Mexico and part of the Southern US. (Source: Wikimedia Commons)

In recent years, this decline has accelerated due to the growth of the illegal totoaba fishing industry. The totoaba is an endangered fish that lives in the Gulf of California and is highly valued for its swim bladder, which is sold for thousands of dollars on the black market in Hong Kong and China. During the 2016-2017 fishing season, even with gillnets banned in the Upper Gulf of California, managers found 150 illegal totoaba nets in the vaquitas’ habitat.

Continuing to focus on deterring illegal totoaba fishing was clearly important to helping the vaquitas, and it was clear that enforcement was needed in addition to successful legislation. But in 2015, proposals began for an emergency ex-situ, or off-site, conservation effort. If the vaquitas couldn’t be saved in their own habitat, maybe they should be taken somewhere they could be protected under human care.

An example of a gillnet: here a Fish and Wildlife Service worker checks on a gillnet which has caught fish. (Source: http://www.fws.gov/digitalmedia/FullRes/natdiglib/11141.jpg)

When conservation in an animal’s habitat isn’t enough

VaquitaCPR was exactly this ex-situ conservation effort, with goals to prepare a vaquita care center, capture wild individuals, and hold them until it was safe for them to be released. It is important to note that ex-situ conservation efforts like this are not replacements for in-situ, or on-site, conservation. Instead, these methods are complementary. Eventual release of vaquitas would require continued effort to make the habitat safe for the species’ survival. And, there was always the chance that ex-situ conservation would fail, leaving only in-situ conservation to save the species from extinction.

Conservation efforts, particularly these type of emergency efforts, trigger philosophical and ethical debates. When is it okay to capture wild animals, particularly wild whales and dolphins? When are risky management efforts considered worthwhile? VaquitaCPR was considered a necessary risk as the population was reduced to merely tens of individuals.

Attempting to capture vaquitas

The actual field efforts to capture vaquitas began in October 2017, after emergency fundraising and intensive preparation of pens and pools to build a vaquita care center. To find vaquitas to capture, scientists used acoustics (listening to the porpoises to try and find them), visual surveys, and trained dolphins from the US Navy. The dolphins would search for vaquitas and alert researchers when they found one.

Two vaquitas were caught during the course of the project. The first was a juvenile female, which appeared agitated when brought back to the care center, so the decision was made to release it. This individual was never re-sighted, but the scientists also never saw a carcass in their continued surveys of the area, so it’s unclear what happened to this individual.

The second captured vaquita was an adult female, who researchers later estimated was at least 15 years-old. This individual was healthy but reacted poorly to capture. After making it safely to the care center, this individual also was agitated and so emergency release was undertaken for this individual as well. Unfortunately, upon release, the porpoise suffered cardiac arrest and died despite on-board veterinarians’ attempts at revival. Post-mortem analysis indicated that the cause of death was capture myopathy – muscle damage from stress.

It’s particularly unfortunate that the two captured individuals were females, as reproductive females are incredibly important for the potential survival of the species. With the extreme stress response of the two captured animals and the death of the second one, VaquitaCPR was concluded. No more captures were attempted due to the risk to the already tiny population.

Images of a juvenile female vaquita from the Rojas-Brancha et al. 2019 paper. This was the first of two individuals captured, and the animal shown here was released after showing signs of stress. Image A was taken at capture, and Image B was taken on release.

At least one animal died. Was it worth it?

Essentially, the story of VaquitaCPR is a cautionary tale, a lesson to conservationists and ordinary citizens alike that emergency projects are more likely to fail then those with lots of time to plan and prepare. This project was proposed because the options available to save the species were so limited. Researchers and conservationists could either risk the potential complications of capture in order to bring porpoises into a safe care center or sit by and watch the final vaquitas die in net entanglements. Neither of these choices were ideal, and the final decision was to do something, anything, that might help.  The moral of the story is that we need to make sure we aren’t stuck in this position again; we need to work to save species far before they ever get to the point that the vaquita is in now.

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