Most migratory fish on the brink says global analysis

At least 2 in 5 migratory animal species prioritised for conservation are in decline and almost all significant migratory fish are threatened with extinction, says a new report.

The State of the World’s Migratory Species report is the first audit of almost 1,200 species deemed by nations subscribing to the Convention on the Conservation of Migratory Species of Wild Animals (CMS) as “needing protection.”

But not every nation is a signatory to the CMS, among them the United States and Canada, and as a result, about 400 migratory species threatened with extinction are not part of the analysis.

Black and white photo of a dead thresher shark on a beach
A dead thresher shark lies on the beach in Puerto Lopez, Ecuador. Overfishing and hunting is posed as one of two major factors pushing fish species to the brink of extinction. Credit: Jan Sochor/Latincontent/Getty Images

Mostly, extinction threats are driven by overexploitation, where overfishing, hunting and capture of non-target animals are devastating many species. Habitat loss, degradation and fragmentation (where human activity separates habitat areas) are also causing major declines.

The plight of migratory species is uneven.

Overall, species abundance – literally how many individuals there are in each species’ population – is either stable or increasing.

More than two-thirds of CMS species are considered relatively safe from extinction.

But this data masks more concerning trends. At a species level, around 44% of monitored species are experiencing population decline.

Professor Richard Fuller is an expert in migratory shorebirds at the University of Queensland. He cautions against the ‘good news’ of overall migratory animal abundance heading into positive territory.

“What’s happening with many migratory species as the most common migratory species are increasing,” Fuller tells Cosmos.

“Some migratory species are doing incredibly well, particularly ones that benefit from human activities.

“Whether that’s a natural thing or not, is really up for debate.

“At the other end of the scale, you have rare migratory species dropping off the end. And that’s where I think the real alarm bells are here.”

Migratory species preservation a test of global cooperation

CMS-listed fish are of particular concern to the convention, which meets in Uzbekistan today for its 14th Conference of Parties, which includes representatives from Australia, New Zealand, all of Europe, most African, South American, Middle Eastern and South Asian nations.

Half of migratory fish are critically endangered, and a further quarter are endangered, and about a fifth are considered vulnerable to extinction.

In all, almost every migratory fish species is now threatened with extinction.

About a third of migratory reptiles are also critically endangered.

Yet the increase in abundance overall points to what Fuller calls clear signs of “ecological imbalance”.

“A species going crazy and superabundant because of human landscape [impacts] that they happen to like, and at the other end of the scale, those rare ones [are] dropping off the face of the planet altogether.”

Godwits flying near sydney's port botany.
Bar-tailed godwits in flight. These hold the record for the longest non-stop flight by a migratory bird species. Credit: Deb Andrews.

Fuller takes the view that solutions exist if nations better coordinate their efforts to preserve species, which is the purpose of the CMS. In particular, he describes a challenging situation, resolving one threat along a migratory route is good, but failure to address issues elsewhere in a species’ path of movement will fail to resolve issues overall.

“Migratory species truly test global commitments to protecting ecosystems and populations,” says Rochelle Constantine, a marine biologist at the University of Auckland.

“Despite decades of research, international agreements, local and global initiatives, 20% of migratory species monitored by the CMS are threatened with extinction.

“We face immense challenges implementing meaningful change for migratory species. Their decline has significant ecological impacts, and reflects rapid environmental change… Also, these animals often indicate rapid environmental change.”

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