Saving seals may come at the cost of fragile flora
The Antarctic fur seal population is growing rapidly. Having rebounded from near eradication by hunters in the early 20th century, Antarctic fur seals are making their way to new frontiers. Their recovery has been so successful, that they are pushing beyond their historical range, creating “unexpected terrestrial conservation problems” for Antarctica’s fragile vegetation. warns of a recent study .
Starting around 2010, fur seals have been expanding from their hub centered on South Georgia island down the Antarctic Peninsula, reaching the southern side of Marguerite Bay. Peter Convey, an expert with the British Antarctic Survey and the lead author of the new study, says that fur seals are now far more south than they were before. This expansion is mainly led by juveniles and nonbreeding males. These fur seals are known to trample fragile coastal vegetation on Antarctica’s limited amount of ice-free land.
Convey identifies the damage that fur seals have done to Signy Island, South Orkney Islands. The landscape there, including the delicate mosses, has been severely impacted by the seals. In 1977, says Convey, there were around 1,600 seals on Signy Island. By the mid-1990s, there were more than 20,000. Their eutrophication has been caused by seals who defecate and urinate near the islands’ freshwater lakes.
Convey is bringing the topic up with his colleagues to spark discussion. He is concerned that the current plans to protect Antarctica, which are overseen by the multi-state Antarctic Treaty, only account for human impacts. He believes that the impact of the seals far exceeds the human ones. Convey states that the Antarctic Treaty is responsible for providing physical protection to the continent’s inhabitants. Convey states that there is no simple answer. Convey believes that it is a valid debate.
Brian Silliman is a marine biologist at Duke University, North Carolina, who was not involved in the research. He suggests that the seals’ expansion could be a result of recolonization to their full historical range. It’s common when looking at rebounding species to think they are “doing things that we thought they’re not supposed to do,” Silliman says. He says that studying populations at their nadir can give false impressions of their behavior and range after decades of loss or overhunting.
It is not clear what the population of Antarctic fur seals was or where they were distributed prior to historical overhunting. Convey however points out that there is no evidence to suggest that seals have ever gallumphed across these coastlines, even before their exploitation.
Convey stresses that culling seals is not an option. The management problem of how to deal with the growing fur seal population is a difficult one that requires difficult decisions. The situation is fundamentally about whether Antarctica’s terrestrial ecosystems should be given priority over its fur seal population.
Claire Christian is the executive director of the Antarctic and Southern Ocean Coalition. This NGO is dedicated to protecting Antarctica and its waters. The Antarctic Treaty System must make tough decisions based on limited information. One approach is to identify hotspots of vegetation that need to be protected from errant Fur Seals. Convey agrees that this is a possible solution. However, taking steps to protect this terrain, such as installing fences, would be another human intervention that could have unintended consequences. Some fences have been installed with mixed results in certain locations.
Christian suggests another approach: to determine what is necessary to make this new normal flourish “instead of trying make it into what you want to see,” she said.
Ally Kristan, a marine biologist who studied rebounding populations on South Georgia Island while at Louisiana State University and was not involved in the research, is “very wary of implementing control methods on a population that has already been so vastly and disastrously affected by human impact.” Regardless of where they used to live, Kristan says, fur seals are now in an altered ecosystem due to past and current impacts. She says there is no way to restore things to “normal.”
This lack of simple answers unites those concerned with protecting Antarctica with those working to manage changing environments elsewhere, such as in the Indian Ocean where dwindling shark populations have allowed green sea turtles to rebound swiftly–and to go on to overgraze seagrass meadows. Along the west coast of North America, recovering populations of sea otters have come into conflict with local people. As other marine predators recover, they may do similarly.
Inadvertently, or not, humans have chosen the winners and losers of ecosystems for millennia. As people recover from past exploitation, and struggle to adapt to altered environments that are more changing due to anthropogenic warming, a hands-off approach seems less feasible.
This article first appeared in Hakai Magazine, and is republished here with permission.
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