February 10, 2010

Marine Zone Helps African Penguins

A colony of threatened penguins in South Africa have a little less too worry about after a ban has been placed on purse-seine fishing around the local region, according to marine biologists on Wednesday.

The African penguin population dropped by 60 percent in the last 9 years, due to human fish trawling and climate change that is taking a toll on their local food supply. A drop in anchovies and sardines, means a drop in African penguins.

There are an estimated 26,000 surviving pairs remaining in the wild. The largest colony is on St. Croix Island in Algoa Bay, on the east coast of South Africa.

Birds were tagged and monitored closely before and after the fishing ban. A 12-mile radius ban was placed around the Algoa Bay colony in January 2009.

Before the ban, three quarters of the bird population had to venture beyond the 12 miles to find food, the biologists found. Within three months of the ban, nearly 70 percent of the penguins were feeding within the prohibited fishing zone, feeding on fish that were previously unavailable.

Another large colony located 30 miles away on Bird Island, is also affected by fish trawling. Fishing is still permitted there and the birds have to take long swims to hunt down food, according to investigators.

The banning of trawling in the St. Croix region is important, because it cuts down on the amount of energy the birds expend hunting for food by 40 percent, "enabling them to invest energy in reproduction," said David Gremillet of France's National Center for Scientific Research (CNRS).

Right now it is still too early to see if the penguins will have more chicks and how many will survive until adulthood. It will take years for studies to show any concrete results, Gremillet told AFP. Because of the big decline over the last decade in populations, it is likely that the African penguin may be classified as "endangered."

There is evidence out there that a threatened species can rebound quickly if you just give a little nudge in the right direction. The ban on local fishing was the right nudge.

"A marine protected area closed to fisheries can have immediate benefits for an endangered marine top predator," say the authors of the study, published by Britain's Royal Society in the journal Biology Letters.

Purse-seine fishing consists of dropping a balloon-shaped net (purse) to a desired depth before raising it back up underneath shoals of fish that swim near the surface. The technique is very effective as it prevents fish from escaping downward to avoid capture.


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