Sockeye decline may be natural event
Web posted at: 4:00 PM EDT
By Environmental News Network staff
(ENN) -- The low number of sockeye salmon returning to Alaska's Bristol Bay over the past two years may be due to a natural, long-term shift in ocean cycles, according to marine scientists.
"It was bound to happen," says Milo Adkison, an assistant professor of fisheries at the University of Alaska Fairbanks School of Fisheries and Ocean Sciences. "You get large year-to-year variations and you also get shifts in salmon abundance that can run for a couple of decades. Salmon productivity itself is connected to conditions in the ocean that operate on similar time scales."
While there has been much press of late about the decline in the world's fisheries due to overfishing, this is not the case with sockeye salmon. Hatchery programs at the Alaska Department of Fish and Game ensure that there are plenty of fish.
"The health of the population is better now than it was 20 years ago," said Adkinson.
The changes in salmon populations over the past two years, said Adkinson, is the likely result of one of two scenarios. Either "two bad years in a row" related to a rise in sea surface temperatures due to the El Ni–o phenomenon, or a long-term shift in ocean cycles known as a regime shift.
"Because there is such a large inter-annual variability, you have a hard time knowing that you're in a new regime until you've seen five years of bad returns in a row or five years of good returns in a row," said Adkison.
Regime shifts occur on a 15- to 20-year cycle and it has been about 20 years since Alaska's salmon stocks rebounded from historic lows, according to Sea Grant scientists at the University of Alaska, Fairbanks.
If the scientists are correct about the onset of a regime shift, the economic repercussions in Bristol Bay could be severe, said Adkinson. An abundant supply of salmon coming from fish farms in Chile and Japan have stabilized salmon prices around the world.
In the old days, before fish farms, a low salmon run meant the fishermen would get a higher price for their fish. In today's market, a low run simply means less money.
On Friday, Alaska Governor Tony Knowles declared western Alaska a disaster area due to the two consecutive years of poor salmon runs. Fishermen and their communities will be the recipients of a $19 million aid package to help ease their economic woes.
The jury is still out as to the cause for the salmon declines, but fingers seem to be pointing at a complex change up of environmental factors.
"Certainly over the last year we have been influenced by El Ni–o," said professor of oceanography Tom Weingartner. "Whether or not that is occurring in conjunction with a regime shift, I don't know."
Scientists have also discovered a significant decline in phytoplankton production, a vital bottom link in the food chain
"The implication is that the Bering Sea has decreased in productivity by 35 to 40 percent since its peak in 1965 or so," said Don Schell, the director of the university's Institute of Marine Science. "Now a 40 percent decline in the carrying capacity of the ecosystem is going to have profound effects on the top consumers, and I think that is in part what we are seeing now. It implies that there is a bottom-up change occurring."
Copyright 1998, Environmental News Network, All Rights Reserved
Back to the top
© 2000 Cable News Network. All Rights Reserved.
Terms under which this service is provided to you.
Read our privacy guidelines.