The additional inriver passage information provided by the lower river sonar helps to fill a long standing management information gap in fish passage trends in the lower Copper River.
Cordova, Alaska (PRWEB) June 09, 2016
It’s all about sustainability.
This year, the Copper River/Prince William Sound Marketing Association funded a sonar project, operated by the Prince William Sound Science Center, to enumerate salmon passing through the lower Copper River on their way to the spawning grounds. Using DIDSON (Dual Frequency Identification Sonar), technicians could “see” salmon swimming upriver. Following the same methodology as the Alaska Department of Fish and Game (ADF&G), salmon were counted by hand as they passed on screen. A daily passage estimate was calculated from these counts and relayed to fishery managers at ADF&G. Because of its location, this sonar counted salmon entering the river days before the Miles Lake sonar.
Why two sonar sites? The Miles Lake sonar project is a well-established management tool operated by ADF&G, and it is located where the Copper River narrows into a single channel. DIDSON transducers are operated on both sides of the river and provide a reliable estimate of total salmon escapement (fish that have escaped the fishery). The lower Copper River sonar uses one transducer and is located in a main channel about 20 miles nearer to the fishing grounds. Though it ensonifies an unknown proportion of the salmon run, the lower Copper River sonar provides valuable information.
Project leader Dr. Rob Campbell says: “As near as we can tell, this is the first time anyone has tried a sonar this low in the delta. We saw some clear pulses of fish moving through, and they appear to correspond somewhat with counts made at Miles Lake a few days later. We will be looking back at counts from both the lower Copper River sonar and the Miles Lake sonar in the near future to assess what proportion of the run was observed by the new site.”
As Dr. Campbell mentions, operating sonar in the lower Copper River gives an indicator of run strength days before those salmon reach Miles Lake. Fishery managers are always in search of more timely data as salmon enter the river. This early information can help fishery managers make better decisions.
According to Jeremy Botz, gillnet fishery manager at the Alaska Department of Fish and Game: “The additional inriver passage information provided by the lower river sonar helps to fill a long standing management information gap in fish passage trends in the lower Copper River.” This means better information for fishery management, thus helping to protect the Copper River salmon run for the future.
Commercial fishermen have been fishing the Copper River for well over 100 years. They know that only with careful management has their fishery become the world-renowned pillar of sustainability that it is today. Only by conservation has their fishery become an industry that can support their families for generations to come. This is why they choose to support fishery assessment projects like the lower Copper River sonar.
The Copper River/Prince William Sound Marketing Association, a fisherman funded regional seafood development association, works on behalf of the 500 plus commercial salmon fisherman of Coastal South Central Alaska. The association works to build brand awareness for wild Copper River king, sockeye and coho as well as Prince William Sound sockeye, keta, and pink salmon.
For additional information contact:
Christa Hoover, Executive Director
Copper River/PWS Marketing Association
Box 199, Cordova, Alaska 99574
t: 907.424.3459:: f: 907.424-3430