Withstanding attacks and criticisms from the Trump administration, the US Endangered Species Act (ESA) appears to be working, with a study of marine animals finding significant population improvement in several vulnerable species.
While over-fishing, habitat loss and degradation, pollution and climate change continue to threaten “elevated levels of extinction risk” among several groups of marine animals and plants, including reef-building corals, sea grasses, sharks and rays and billfish, the study identifies populations of endangered sea creatures that are showing signs of recovery.
The work, by Abel Valdivia, Shayne Wolf and Kieren Suckling from the US Centre for Biological Diversity in Arizona and published in the journal PLOS One, examined the status of marine mammal and sea turtle populations after their being listed under the ESA.
They looked at populations of species that were listed before 2012, which are found and reproduce in US waters, and for which there is sufficient good-quality data to allow trend analyses.
They gathered the best available annual abundance estimates for populations of all 62 marine mammal species and sea turtle species listed under the ESA, and analysed population trends and recovery status for 23 representative populations of 14 marine mammal species and eight representative populations of five sea turtle species.
The researchers found that 18 marine mammal and six sea turtle populations significantly increased after listing; three marine mammal and two sea turtle (25%) populations remained constant; and two marine mammal – but no sea turtle – populations declined after ESA protection.
The 24 populations that increased in abundance were from species listed for 20 years or more and included large whales, manatees and sea turtles.
The authors say that since the law was enacted, in 1973, the Act has “shielded more than 99.5% of the species under its care from extinction”. They add that “without the ESA’s protection, an estimated 227 species would have disappeared by 2006”.
The report notes that species recovery is associated with effective implementation of the tools enabled by the Act, funding for recovery actions, the presence of a dedicated recovery plan, and the recognition of critical habitat.
Despite the successes noted in the report, the authors point out that there are 163 marine species listed as threatened and endangered under the ESA, as of August 2018, including species, subspecies, and distinct population segments for vertebrates, but that evaluations of the ESA’s record in protecting marine species are lacking, especially for the 62 marine mammal and sea turtle species listed.
The report remarks that previous studies have demonstrated that “the government’s failure to fully implement the ESA’s protections and adequately fund conservation actions have been major impediments to species recovery”, but it notes that, in general, listed species with designated critical habitat, sufficient conservation funding, and well-implemented species-specific recovery plans tend to recover relatively faster.
“Our analysis not only underscores the capacity of marine mammal and sea turtle populations to rebound after decades of exploitation and habitat degradation, but also highlights the success of marine species conservation through a combination of ESA protection and other conservation efforts.”
Related reading: Endangered animals you should know