Posted by California DFG on September 16, 2010 at 23:32:17:|
California Department of Fish and Game News Release
FOR IMMEDIATE RELEASE - September 15, 2010
Contacts: Carol Singleton, Dept. of Fish and Game, (916)327-9948 Mike Harris, Dept. of Fish and Game, (805) 772-1135
Sea Otter Deaths From Shark Bites on the Rise
The Department of Fish and Game (DFG) reported collecting a record number of shark-bitten sea otters in August along California's central coast.
Scientists collected 19 injured or dead otters with signs of shark bites in August and seven already in September. The majority of the otters were collected in the Morro Bay-Pismo Beach area. The 10-year average for August is seven otters, and for September is six.
Scientists believe this increase in shark-bitten otters in California may be due to cooler than average ocean temperatures from an unusually mild summer, creating an ideal condition for white sharks.
"White sharks do not typically feed on sea otters," explained Michael Harris, environmental scientist with DFG's Office of Spill Prevention and Response. Harris has been working with sea otters for 19 years. "Their preferred prey is seals and sea lions. This would explain why the majority of the otters collected have a single bite mark. These bites are more investigative - like a taste test."
White sharks occur around the world, mostly in cold, temperate seas with a surface temperature of 50 to 72 degrees Fahrenheit. As top-level predators, sharks serve the marine environment by helping keep seal and sea lion populations in check. As white sharks grow, they transition from feeding on fish as juveniles to feeding on marine mammals with high blubber content like seals and sea lions.
"Without much data on the white shark population off California, we can only speculate as to the cause for the increase in the otter bites," said Harris. "But perhaps there are more juvenile sharks in the area, testing various prey items as they transition."
Sightings of white sharks by humans may have also increased this year based on anecdotal information provided on a number of websites.
No population estimates exist for white sharks. Some DNA studies, efforts to tag sharks and attempts to identify individual sharks by unique characteristics have occurred, but the research remains limited.
While white sharks typically do not prey upon humans, water enthusiasts are encouraged to remain aware of their presence in the marine environment. According to DFG's latest available numbers, California has had 95 white shark attacks since 1950 with only 11 fatalities. Even with population growth and increased human activity in marine waters, the number of incidents involving white sharks has not increased in parallel.
California swimmers, divers, surfers and others can reduce the likelihood of a shark encounter by avoiding places known for white sharks, such the Farallon Islands, Aņo Nuevo and Bird Rock near Point Reyes. Further, avoid areas where sea lions, harbor seals and elephant seals congregate, including their rookeries. Times of reduced sunlight such as foggy mornings or dusk are also high risk times as the human silhouette is more likely to be mistaken for a seal resulting in a bite.
Though not protected as a threatened or endangered species, California regulations prohibit the take of white sharks under a sportfishing license and the commercial fisheries are prohibited from targeting the species.
For more on white sharks, please visit www.dfg.ca.gov/marine/pdfs/sharkfacts.pdf.