recentpopularlog in

robertogreco : chlorophyll   1

Something Fishy in the Atlantic Night : Feature Articles
"About 300 to 500 kilometers (200 to 300 miles) offshore, a city of light appeared in the middle of the South Atlantic Ocean. There are no human settlements there, nor fires or gas wells. But there are an awful lot of fishing boats.

Adorned with lights for night fishing, the boats cluster offshore along invisible lines: the underwater edge of the continental shelf, the nutrient-rich Malvinas Current, and the boundaries of the exclusive economic zones of Argentina and the Falkland Islands.

The night fishermen are hunting for Illex argentinus, a species of short-finned squid that forms the second largest squid fishery on the planet. The squid are found tens to hundreds of kilometers offshore from roughly Rio de Janeiro to Tierra del Fuego (22 to 54 degrees South latitude). They live 80 to 600 meters (250 to 2,000 feet) below the surface, feeding on shrimp, crabs, and fish. In turn, Illex are consumed by larger finfish, whales, seals, sea birds, penguins...and humans.

The fishery is fueled by abundant nutrients and plankton carried on the Malvinas Current. Spun off of the Circumpolar Current of the Southern Ocean, the Malvinas flows north and east along the South American coast. The waters are enriched by iron and other nutrients from Antarctica and Patagonia, and they are made even richer by the interaction of ocean currents along the shelfbreak front, where the continental shelf slopes down to the deep ocean abyssal plain.

Scientists first noted such night-lighting of the seas in the late 1970s and early 1980s, while compiling the first maps of the Earth at night. The images from the Operational Linescan System on the polar-orbiting satellites of the Defense Meteorological Satellite Program (DMSP) clearly showed fishing boats working the waters off of Japan, China, and Korea.

Fisheries researchers and managers suggest that as much as 300,000 tons of Illex squid are harvested from the South Atlantic each year by unlicensed, unregulated fishing vessels. Managing the fishery and monitoring the presence of foreign fishing fleets is very difficult for navies and fisheries managers; the satellite views provide at least some sense of the activity in the area.

“These lights help reveal the full range, patterns, and night-to-night variability of these fishing activities in striking detail,” said Steve Miller, a Colorado State University scientist who works with VIIRS nighttime imagery. “It’s just another example of how much information exists in these measurements and how unique they are for coupling human activity with the natural environment in a way that conventional visible imagery cannot do.”"

[via: ]
malvinas  falklands  fishing  argentina  atlantic  night  light  squid  cephalopods  chlorophyll  plankton 
october 2013 by robertogreco

Copy this bookmark:

to read