(from ARKive)
Listed as Critically Endangered by the IUCN, the Hawaiian monk seals in a marine protected area are heading towards extinction, while those in a nearby unprotected area are thriving, according to new research, and its populations continue to decline as a result of human disturbance, low food availability and entanglement in marine debris.New research, published in the journal Conservation Letters, reports that the Hawaiian monk seal population in Hawaii’s Papahānaumokuākea Marine National Monument, home to 85% of the Hawaiian monk seal population, is declining by about 4% a year. In contrast, a population in the main Hawaiian Islands is increasing by 7% a year, despite fishing, development and boat activity all being permitted in the area.
Suggested causes of the decline include increased shark predation within the reserve. Fishing was banned in the area in 2006, but fishing discards prior to this may have boosted shark numbers, and these sharks could now be wreaking havoc on seal pups. Some locals have even started a shark-culling programme to control ‘problem sharks’. Other possible explanations include changes in the seal’s food supply due to warming waters, and competition for food from large fish known as jacks. Both could be contributing to the low pup survival which is driving the monk seal’s decline. Alternatively, the reserve may simply be too new for its ecosystem to have settled down.
Officials have been looking at ways to boost the Hawaiian monk seal’s population in the marine reserve. Suggested measures include moving weaned pups from the reserve to areas with higher survival rates, and then returning them to the reserve when they are older and less vulnerable. According to the researchers, moving the pups may be a good idea for now, but they should not be moved back until things change in the reserve. However, conservationists have yet to determine what might need to change.
“It depends how you define success. Is it about saving endangered species, or preserving a functioning ecosystem? It’s worth taking a step back. Marine preservation areas may not be the solution in all situations.” - Leah Gerber, Professor ASU School Of Life Sciences
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