OTHER REASONS SURFACE FOR HERRING DECLINE
By CRAIG MEDRED
Almost 30 years after the oil tanker Exxon Valdez hit Bligh Reef and smeared Prince William Sound with more than 11 million gallons of Alaska crude oil, a team of state and federal scientists have concluded the spill – as bad as it looked and as much impact as it had on marine mammals and birds – appears to have done no real damage to fisheries.
“We found no evidence supporting a negative EVOS (Exxon Valdez Oil Spill) impact on herring, sockeye salmon, or pink salmon productivity, and weak evidence of a slightly positive EVOS signal on Copper River Chinook (king) salmon productivity,” the study says. “It is unclear how EVOS may have impacted Chinook salmon positively.”
Somewhat surprisingly, however, the study found two non-oil spill events – one natural and one manmade – that appear to have caused significant changes in Sound fisheries. And one of them, a naturally occurring spill of fresh water, appears to be what crippled herring stocks there.
Exxon has long been blamed for the collapse of herring, which once supported a fishery worth $6 to $11 million per year, but the new study funded by the Exxon Valdez Oil Spill Trustee Council, a government entity established to track the Sound’s recovery in the wake of the spill, fingers fresh water as the real culprit.
“Herring productivity was most strongly affected by changing environmental conditions,” the study says, “specifically, freshwater discharge into the Gulf of Alaska was linked to a series of recruitment failures—before, during, and after EVOS (Exxon Valdez Oil Spill).”
And the other big factor driving significant environmental changes in the Sound?
The annual spills of hundreds of millions of pink salmon fry.