The Alaska Department of Fish and Game released a Frequently Asked Questions document designed to answer questions about the 2013 Kenai River king salmon runs.
The four-page document, posted to the ADFG web page Friday evening, answers questions about ADFG estimates of size and age of king salmon that made it into the Kenai River during the 2013 season, the sonar programs used to estimate salmon abundance and how ADFG managers use the data to meet escapement goals.
ADFG staff have repeatedly referred questions about 2013 post-season analysis of king salmon data to the impending release of the FAQ document.
Two sonar sites are currently being used to count king salmon by ADFG staff, though just one —located at river mile 8.6 is being used for management.
The second site, one at river mile 13.7 saw its first full season of operation in 2013 as managers assess its feasibility in becoming the new primary tool for counting and managing king salmon in the Kenai River.
According to the document, the new sonar site was “successful” and will be used again in 2014.
“(ADFG) is in the process of refining objectives and study design for 2013 sonar research to ensure that the River Mile 13.7 sonar will operate under all conditions of water flow and fish passage, including the possibility of large number of pink salmon that may be present in 2014,” according to the document.
The test site as yet to be tested in a pink salmon year and concerns are that large volumes of the fish could impact how researchers count king salmon, said Southcentral Region supervisor Jim Hasbrouck in a Dec. 5 interview.
One issue with the sonar currently being used for management is its ability to detect smaller fish as accurately as it does with larger fish.
“Nearly all large fish counted by the sonar are king salmon, so this count is very accurate,” according to the document. “To count small king salmon we use additional information from our netting program to determine the proportion of all species of small fish counted by the sonar that are king salmon.”
ADFG data on the age of the early run of king salmon has shown an increase in the number of younger —therefore smaller — king salmon swimming up the river between 2010-2013.
“Based on data from weirs on some of the tributary streams we probably underestimated how many of these small fish entered the river during these years,” according to the document.
The final 2013 king salmon escapement estimate on the early run — based on estimates of fish passage by the sonar and netting data with harvest upriver of the sonar site subtracted — was 2,032 fish, well below both of its target escapement goal ranges, according to ADFG data.
The document also details inseason management actions the department took to attempt to meet king salmon escapement goals including prohibiting harvest of early-run king salmon, and a strategy to limit king salmon harvest in the commercial setnet fishery during the late run of king salmon.
The preliminary late-run king salmon escapement was just over 15,300 fish, with 1,620 king salmon estimated to have been killed by sport fishers; 2,256 in the by commercial setnet fishers and 426 by commercial drift fishers. The final escapement number factors in harvest data.
The document is available on the ADFG website or at http://1.usa.gov/1ccBjab
Reach Rashah McChesney at firstname.lastname@example.org