The ocean’s mammals are at a crucial crossroads – with some at risk of extinction and others showing signs of recovery, researchers say.
In a detailed review of the status of the world's 126 marine mammal species — which include whales, dolphins, seals, sea lions, manatees, dugongs, sea otters and polar bears — scientists found that bycatch, the accidental capture of marine mammals during commercial fishing, coastal habitat destruction, climate change and pollution are among the key drivers of the decline of an increasing number of species.
A quarter of these species are now classified as being at risk of extinction (vulnerable, endangered or critically endangered on the IUCN Red List), with the near-extinct vaquita porpoise and the critically endangered North Atlantic right whale among those in greatest danger.
Conservation efforts have enabled recoveries among other species, including the northern elephant seal, humpback whale and Guadalupe fur seal.
FIU Institute of Environment Assistant Professor Jeremy Kiszka was among the international team of researchers from 30 institutions in 30 countires who co-authored the study published in the journal Endangered Species Research.
“We need to address a large number of threats at the same time,” Kiszka said. “It helps to realize that the task is getting bigger and the threats are more significant.”
The study examined a range of conservation measures including Marine Protected Areas, bycatch reduction methods and community engagement as methods to stem the tide against extinction for some species.
"We have reached a critical point in terms of marine mammal conservation," said the study’s lead author, Sarah Nelms, a postdoctoral researcher at the University of Exeter’s Centre for Ecology and Conservation in England. "Very few marine mammal species have been driven to extinction in modern times, but human activities are putting many of them under increasing pressure.
The researchers say 21% of marine mammal species are listed as "data deficient" in the IUCN Red List – meaning not enough is known to assess their conservation status.
This lack of knowledge makes it difficult to identify which species are in need of protection and what actions should be taken to save them.
“Research efforts in developing countries along with capacity building are critical to assess the conservation status of many poorly known species,” Kiszka said. “The future of marine mammals and marine conservation in general also depends on our capacity to inspire and help students and local researchers, particularly in developing countries, where marine mammal conservation issues are poorly known and where needs are increasing.”