Fish skin lesions, oil residue decline in years after Gulf oil spill

Scientists studying the impact of the 2010 Deepwater Horizon oil spill on the health of fish in the Gulf of Mexico have found strong evidence that an outbreak of skin lesions and oil residue signatures discovered in fishes a year after the spill may be related to the catastrophe.

Publishing in Transactions of the American Fisheries Society, scientists from the University of South Florida (USF), the Florida Institute of Oceanography (FIO) and the Florida Fish and Wildlife Research Institute (FWRI) reported that there was strong chemical resemblance of the oil from the Deepwater Horizon blowout to that found in the fish livers and muscle of fishes sampled from the northern Gulf of Mexico. The researchers were also able to rule out pathogens and oceanographic conditions as potential causes for the lesions.

"The higher rates of skin lesions in 2011 vs. 2012 were not due to an outbreak of pathogens or abnormally low salinity, and thus the hypothesis that DWH was responsible for the higher rates of skin lesions remains viable," said researcher Steven Murawski, a professor of population dynamics and marine ecosystem analysis at USF's College of Marine Science.

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Polar bears showing signs of disease that killed seals in Alaska in 2011

Are Polar bears succumbing to same disease?
April 2012. In the past two weeks, 9 polar bears in the southern Beaufort Sea region near Barrow in Alaska were observed with alopecia, or loss of fur, and other skin lesions. The animals were otherwise healthy in appearance and behaviour. 

The cause and significance of the observed lesions are unknown. Alopecia has been reported in both wild and captive animals in the past. U.S. Geological Survey scientists have collected blood and tissues samples from afflicted polar bears to investigate the cause of the symptoms and determine whether there is any relationship between the symptoms observed in polar bears and those reported for arctic pinnipeds (Seals and walrus) from the same geographical region earlier this year.

Research scientists with the USGS made the observations at the start of their 2012 field-work season. USGS observes polar bears annually in the southern Beaufort Sea region as part of a long-term research program. This bear population ranges from Barrow in Alaska east to the Tuktoyuktuk region of Canada.

Disease first appeared in seals in 2011
Observations last summer of unusual numbers of ringed seals hauled out on beaches along the Arctic coast of Alaska, and later on, of dead and dying seals with hair loss and skin sores, led to declaration of an Unusual Mortality Event by the National Oceanic and Atmospheric Administration on December 20, 2011. Based on observations of Pacific walruses with similar skin lesions at a coastal haul-out in the same region during fall, the U.S. Fish and Wildlife Service joined the UME investigation. Most walruses exhibiting skin lesions appeared to be otherwise healthy, and whether the symptoms observed in the seals and walruses are related is unknown. 

Ice seals with similar symptons
Since the initial reports from northern Alaska, ice seals with similar symptoms have also been reported in adjacent regions of Canada and Russia and from the Bering Strait region. 

Cause unknown - Disease or toxins?
Despite extensive testing for a wide variety of well known infectious agents, the cause(s) of the observed condition in walruses and ice seals remains unknown. Advanced testing techniques for unidentified infectious agents is continuing as well as further testing for potential causes including man-made and natural biotoxins, radiation, contaminants, auto-immune diseases, nutritional, hormonal and environmental factors.

Report sick polar bears
Anyone observing or harvesting (Why call it harvesting - Everyone knows it means hunting? Ed.) a polar bear with fur loss or skin sores is encouraged to report their sightings by calling the USGS polar bear hotline at 907-786-7034 or the local numbers established for reporting sightings of affected seals and walruses.

These numbers include: 
Barrow/North Slope: North Slope Borough Dept. of Wildlife Management • 907-852-0350
Nome/Bering Strait: Eskimo Walrus Commission • 1-877 277-4392
UAF Marine Advisory Program • 1-800-478-2202 or 907-443-2397 
NOAA Alaska Marine Mammal Stranding Network • 1-877-925-7773
Alaska Nanuuq Commission • 1-907-443-5044

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