For the Bristol Bay watershed in Southwest Alaska, the world’s largest sockeye salmon fishery, strength lies in a network of habitat diversity, says Daniel Schindler, a University of Washington professor who has spent years researching the area.
There is diversity in the watershed, with rivers compensating for each other, much like a diversified investment portfolio, Schlindler told the Matanuska-Susitna Salmon Science and Conservation Symposium in Palmer on Nov. 17.
Within the watershed, habitat variation is important at very small scales, with each set of habitat having its own features, he said.
“The message here is what do we do to maintain the differences in the watershed,” Schindler told dozens of biologists, conservationists, and commercial, sport and subsistence harvesters packed into the old train depot in downtown Palmer that serves as the city’s community center.
“We can do a lot of tangible things now to protect ecosystems, to make ecosystems resilient to climate change,” he said. “Protecting habitat networks is a way to build climate resilience. Stability and productivity of fishery systems is derived from diverse and changing habitat.”
Schindler, who teachers undergraduate and graduate students in limnology, aquatic sciences and ecology at UW, has been doing research on the Bristol Bay watershed for more than two decades.
Commercial fishing for sockeye salmon in Bristol Bay has been happening for about 130 years, and has been sustainable because the commercial fishery interacts with a sustainable population because individual rivers compensate for each other, he said.
Most of Alaska’s rivers currently remain free-flowing, and it is the absence of dams and other infrastructure that allows rivers to meander across their floodplain area, those low lying areas of ground adjacent to a river, formed mainly of river sediments and subject to flooding. As the rivers meander, they produce complex mosaics of aquatic habitat generated by erosion and deposits of sediment.
“The Bristol Bay fishery is remarkably productive,” Schindler said. “There is the importance of reliability of returns. There is distinct social and economic value in consistency,” and the reliability of Bristol bay affects people’s dependence on fisheries, he said.
The experience from the Lower 48 states demonstrates that development of floodplains depresses the flows of ecosystem services provided by rivers, and that restoration is exceedingly expensive and often not possible once infrastructure is in place,” Schindler warns in his abstract on the presentation. “Assessments of the risks to the functioning of Alaska’s rivers must embrace their complexity and dynamism to fully capture what might be lost under different development scenarios,” he wrote.
Researchers at the University of Washington have been studying this salmon habitat since the 1940s, long before Alaska became a state. Back in the 1930s concerns rose that salmon were being overharvested and declining in abundance. The fishery at the time was being managed from Washington D.C., and canneries didn’t know about how to manage, so they approached UW around 1945 -1946 to start doing the research, and UW biologists have continued that research since,
Despite obvious climate change, the fishery remains resilient because each river in the Bristol Bay watershed is genetically distinct, down to the smaller rivers and tiny streams. Taking away some of the streams would weaken the strength of that diversity, he said.
The U.S. Environmental Protection Agency, after hearing extensive testimony regarding the copper, gold and molybdenum Pebble mine proposed in the area, concluded that mining the Pebble deposit would affect the South Fork Koktuli River, North Fork Koktuli River and Upper Talarik Creek watersheds, and has proposed to restrict discharge of dredged or fill material related to mining the Pebble prospect.
The EPA cited concerns about potential loss of five miles or more of streams with documented salmon occurrence of all five species of salmon, or the loss of 19 or more miles of streams where salmon are not currently documented, but that are tributaries of streams with documented salmon occurrence.
The EPA also expressed concern over potential loss of 1,100 or more acres of wetlands, lakes and ponds that connect with streams with documented salmon occurrence or tributaries of those streams.
Supporters of the mine maintain that they can develop and operate the mine in harmony with the salmon fisheries, which are critical to commercial, sport and subsistence harvesters, as well as an extensive variety of wildlife in the watershed.
