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IUCN survey suggests that almost half of Caribbean freshwater fish are threatened with extinction

July 31, 2021
The Zapata swamp in Cuba, home to the critically endangered ‘living fossil’ Cuban gar, which is increasingly threatened by the spread of non-native catfish. Image: Marjon Melissen | Flickr Creative Commons

The Caribbean islands are home to a rich diversity of freshwater life, including 79 species of fish which are unique to the region’s shallow streams, lakes and wetlands. However, a new IUCN survey suggests that 41% of Caribbean freshwater fish are threatened with extinction.

The survey represents the first comprehensive assessment of freshwater fish populations in the Caribbean. It shows that fifty-four of the region’s fish species are endemic to the two largest islands, Cuba and Hispaniola, with fewer other endemics found on smaller islands.

“Freshwater fishes are one of the most threatened groups of vertebrates on the planet,” says Tim Lyons, Species Survival Officer at the ABQ BioPark and project coordinator for the assessment. “When you think of the Caribbean, the first thing that comes to mind are visions of beaches and coral reefs, but freshwater fishes are just as important. We depend on them and the watersheds they live in for everything from food to energy.”

The survey suggests that freshwater fish populations in the Caribbean are subject to multiple pressures, including habitat loss, pollution and the spread of invasive non-native species. Whilst its findings are stark, it is hoped that the survey will provide a basis for conservationists and local communities to develop plans to conserve and restore freshwater ecosystems across the region.

“This new assessment sheds light on the critical need for directing more resources to conserving the unique freshwater fishes of the Caribbean, given they face a risk of extinction higher than the global average and include many species found nowhere else on Earth,” says Dr. Harmony Patricio, Conservation Programme Manager for Shoal.

A Jumbie Teta (Ancistrus trinitatis) on a shallow streambed in Trinidad. The species was assessed as Near Threatened due to its limited range and continuing habitat decline associated with human pressures. Image: Amy Deacon.

“Beyond the species known so far, the insular Caribbean holds an incredibly valuable diversity of freshwater fishes still to be discovered, described and understood,” adds Dr. Jose Ponce de Leon from the IUCN freshwater fish working group. “This IUCN report shows the overwhelming need of protecting Caribbean freshwater habitats and educating ourselves and others about their values and threats. This project is an important step in identifying conservation priorities in the Caribbean and highlights the value of collaborative research and inclusive strategic alliances for conservation biology.”

The spread of invasive non-native species was highlighted by the survey as a significant threat to freshwater fish populations in the Caribbean. Native to the Zapata swamp in Cuba, the Cuban gar can reach over two metres in length. Known as a ‘living fossil’, barely changed since the late Jurassic period, the Cuban gar plays an important apex predator role in wetland food webs. 

However, the spread of the African walking catfish (or ‘claria’) to the island following aquaculture introductions has significantly impacted populations of Cuban gar and other fish species. The catfish are large, mobile and predatory, and can outcompete gar and other species. As a result, the Cuban gar is now listed by the IUCN as critically endangered.

A juvenile Cuban gar. Image: Erik Garcia-Machado

Another key pressure highlighted by the survey is ongoing habitat loss and pollution. For example, Lake Miragoane is a coastal freshwater lake on the Tiburon Peninsula of southwestern Haiti. The lake supports 10 critically endangered fish species from the genus Limia – tiny livebearing fish – which are found nowhere else in the world. However, their populations are increasingly threatened by water pollution and deforestation around the lake.

“The primary threats to freshwaters in the Caribbean are consistent with the threats that are driving extinction in other parts of the world, and the extinction risk that these species face is a clear indicator of an ecosystem in distress,” suggests Tim Lyons. “The IUCN has declared 80 species of freshwater fishes extinct, with hundreds more likely to have gone extinct before their formal description or assessment on the IUCN Red List. We must act now to prevent unique Caribbean species from joining them.”

“These assessments are a critical step towards the conservation of freshwater fishes in the Caribbean,” says Dr. Yolanda León, President of Grupo Jaragua, an organisation based in the Dominican Republic which works on biodiversity conservation on Hispaniola.

Grupo Jaragua led the recent submission of an IUCN Resolution which recognises the Caribbean as a significant biodiversity hotspot, and calls for increased regional and international action to halt biodiversity loss. “The results of these Red List assessments will help identify freshwater conservation priorities that can address the objectives of that IUCN Resolution,” Dr. León suggests.


IUCN Freshwater Fish Specialist Group

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