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August 2011 Issue

AgriMarine to Rear Bluefin Tuna on a Commercial Scale in Japan
AgriMarine Holdings Inc. (Vancouver, Canada) announced in June it has entered into an agreement with Tokai University in Japan for a project to rear bluefin tuna on a commercial scale using AgriMarine's proprietary solid-wall closed containment systems.

AgriMarine will collaborate with the School of Marine Science and Technology at Tokai University's Shimizu campus to scale up research and establish husbandry and design parameters for rearing bluefin tuna in closed containment to commercial production levels.

Bluefin tuna is one of the most prized fish worldwide but currently faces overfishing and is at risk of collapse. Demand is at an all-time high—a 342-kilogram bluefin tuna was recently sold by auction at the Tsukiji fish market in Japan for a record 32.49 million yen ($400,000).

Bluefin tuna currently faces pressure due to intensive overfishing and is at risk of collapse. In captivity, they are reared in net cages, which have had limited success due to a number of factors, including challenges associated with breeding, feed and maintaining a suitable environment. Recent research at Tokai University has led to patents related to bluefin tuna juvenile feeding and husbandry. For more information, visit http://agrimarine.com.

Plankton Species Makes First Known Trans-Arctic Migration
Some 800,000 years ago—about the time early human tribes were learning to make fire—a tiny species of plankton called Neodenticula seminae went extinct in the North Atlantic.

Today, that microscopic plant has become an Atlantic resident again, having drifted from the Pacific through the Arctic Ocean thanks to dramatically reduced polar ice, scientists from project CLAMER, a collaboration of 17 marine institutes in 10 European countries, reported in June.

The melting Arctic has opened a northwest passage across the pole for the algae, a development some experts say could have major repercussions for existing Atlantic ocean life.

The discovery is "the first evidence of a trans-Arctic migration in modern times" related to plankton, according to the Sir Alister Hardy Foundation for Ocean Science (SAHFOS), whose researchers say that "such a geographical shift could transform the biodiversity and functioning of the Arctic and North Atlantic marine ecosystems."

The plankton's migration parallels the arrival last year of a Pacific gray whale spotted off the coasts of Spain and Israel, a species that vanished from the Atlantic three centuries ago, likely because of overhunting. Scientists said the ice-reduced Arctic let the whale to cross into the North Atlantic and then wander into the Mediterranean Sea.

"The migrations are an example of how changing climate conditions cause species to move or change their behavior, leading to shifts in ecosystems that are clearly visible today," said Carlo Heip, director general of the Royal Netherlands Institute for Sea Research, which leads CLAMER.

Populations of copepods are changing too, threatening the food supply of fish such as cod, herring and mackerel, as well as the many marine mammals that, in turn, prey on fish, SAHFOS scientists said. For more information, visit www.clamer.eu.

Biological Hot Spots Important For Predators, Researchers Find
A decade-long study of apex predators in the Pacific Ocean found a wider range of distribution among some species than previously thought. The study also revealed unknown relationships between other species and showed the importance of biological hot spots to the survival of most of these sea creatures.

The Tagging of Pacific Predators (TOPP) field program looked at 23 species from 2000 to 2009 and included researchers from multiple institutions. The results of TOPP, the first ocean basin-scale study of marine predator distribution and movement ever conducted, were published in June in Nature.

Researchers found the top predators in the California Current System have many similarities, said Bruce Mate, director of the Marine Mammal Institute at Oregon State University and co-author on the study.

"There is a strong overlap in territory, for example, between blue whales and tuna. Blue whales eat krill; the tuna eat fish that eat the krill," Mate said. "But the krill and the ocean conditions that promote its abundance are key to both species. When there are hot spots of krill or other food, the apex predators need to find them."

Most hot spots result from upwelling. One such spot occurs just west of Santa Barbara, California, where the wind coming around Point Conception triggers a strong upwelling.

"When the winds there died, we watched whales eat literally all of the available food in three days, and then they just took off," Mate said. "Blue whales likely know these hot spots from experience. Instead of waiting for upwelling to renew the krill population, they'll travel 400 miles in three days to find a new food source."

The study shows the importance of apex predators in ecosystems, and noted how the loss of bluefin tuna and porbeagle sharks in the Atlantic Ocean contributed to the near-extinction of cod and similar species. For more information, visit http://oregonstate.edu.

Researchers Discover Plastic in 9 Percent of North Pacific Fishes
Scripps Institution of Oceanography researchers with the Scripps Environmental Accumulation of Plastic Expedition (SEAPLEX) found evidence of plastic waste in more than 9 percent of the stomachs of fish collected during their voyage to the North Pacific Subtropical Gyre. The study's results were published June 27 in Marine Ecology Progress Series.

Study authors and Scripps graduate students Peter Davison and Rebecca Asch estimate that fish in the intermediate ocean depths of the North Pacific ingest plastic at a rate of roughly 12,000 to 24,000 tons per year. Of the 141 fishes spanning 27 species dissected, SEAPLEX found 9.2 percent of the stomach contents of midwater fishes contained plastic debris, primarily broken-down bits that were so small their origin could not be determined. For more information, visit http://scrippsnews.ucsd.edu.


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