Recovery of Once-Endangered Marine Species Spurs New Conservation Challenges

July 11, 2015

Tim Lucas, 919-613-8084,

Editors’ Note: Joe Roman is available for additional comment at or (617) 312-2241.

DURHAM, N.C. – Thanks to recent conservation successes, several iconic once-endangered marine species, including the humpback whale, gray seal, northern elephant seal and green sea turtle, have recovered and are repopulating their former ranges.

But these returning species, whose recovery defies global patterns of biodiversity loss, have created a new challenge for policymakers and coastal communities, a recent review by researchers at the University of Vermont and the Duke University Marine Lab suggests.

“After generations away, these forgotten species can suddenly be seen as newcomers – or even pests,” says Joe Roman, a Fellow at Vermont’s Gund Institute for Ecological Economics and a Mary Derrickson McCurdy Visiting Scholar at the Duke Marine Lab.

While many people embrace the environmental and economic benefits of the returning species – several of which are large predators – others view the animals’ recovery as a hostile invasion, encroaching on key fishing and recreation areas, Roman explains.  The return of North Atlantic gray seals has been blamed in Massachusetts for declining fishery yields and attracting sharks to Cape Cod. Some fishermen in Alaska and Washington State blame returning whales for reducing black cod and salmon stocks. In California, harbor seal pupping has resulted in temporary closures of public beaches.

“The takeaways here are that conservation clearly can work, which is important to celebrate given the trend of declining global biodiversity,” says Roman. “But wildlife managers need to plan for the return of these species to avoid future conflicts.”

“We need to do a better job of communicating these conservation successes to the public, so people understand that predators that were once abundant and important parts of the coastal ecosystem are returning, so that they can learn to co-exist with them again,” says David Johnston, assistant professor of the practice of marine conservation and ecology at Duke.

In their paper, which was published in June in the peer-reviewed journal Trends in Ecology and Evolution, Roman, Johnston and their colleagues make four recommendations for addressing this problem.

First, they say, management agencies need to anticipate possible impacts and conflicts caused by a returning species, and work with local stakeholders to help them adapt to the species’ reemergence and understand the animals’ importance to their local ecosystem.

“We should apply geospatial mapping expertise and predict the places where these animals could show up soon, so people in those areas – who might never have seen the species in decades or even lifetimes – are ready and prepared to deal with their return,” says Meagan Dunphy-Daly, a Knauss Marine Policy Fellow who got her Ph.D. at the Duke Marine Lab.  

The team’s second recommendation is that government agencies should delist some species, such as humpback whales, that no longer require special protection. This would allow conservation efforts to be shifted to other species that are still endangered or threatened, and do require special protection.

The team’s third recommendation is to improve policy decisions for nuisance-animal killings by assessing the total costs and benefits – economically, environmentally, and culturally – of relocating or culling returning species, versus learning to live with any potential effects they have on local fisheries, tourism, recreation or public safety. “We need to figure this out,” Johnston says. “Until now, people have rarely done this; they haven’t analyzed all the costs and explored the available options.”

Last but not least, the researchers say, we need to celebrate conservation successes with the public and lift baselines for recovering species.

“People need to see that we can recover these animals,” Roman says. “In doing so, they become more willing to invest into these practices and initiatives.”

In their review, the researchers looked at population data for marine mammals and other protected species. Of the 87 cetacean species (whales, dolphins and porpoises) examined, 22 are recovering, 15 are endangered and 45 cannot be evaluated because of data limitations. Twenty-six species of pinnipeds (seals, sea lions, and walruses) are secure, and 13 are endangered.

Great whales represent a major conservation success, the researchers say. Of the 14 species, four have seen dramatic recoveries, three are stable, and seven cannot be fully analyzed because of lack of data. Ten of 14 populations of humpback whales could be removed from the U.S. endangered species list this July. This coastal species, popular among whale watchers, was recently seen off the coast of New York City for the first time in generations. The recovery of these and other marine species are due to global conservation efforts, especially national and international wildlife protection acts, such as the Convention on International Trade in Endangered Species and the U.S. Endangered Species Act, which have reduced commercial hunting, protected habitats, controlled invasive species, and guided reintroduction efforts.

While the review highlights conservation successes, the researchers note that more species are declining worldwide than growing. Large predatory fish have declined by two-thirds in the past century, and at least three species of marine mammals have gone extinct since the 1950s.

Andrew Read, Stephen Toth Professor of Marine Biology at Duke, was also an author of the new review.

Support for the paper came from the Mary Derrickson McCurdy Visiting Scholar Program at Duke, and a National Marine Fisheries Service Sea Grant Population Dynamics Fellowship.


CITATION: “Lifting Baselines to Address the Consequences of Conservation Success,” Joe Roman, Meagan M. Dunphy-Daly, David W. Johnston, Andrew J. Read; published June 2015 in Trends in Ecology and Evolution.