Sound Science: Investigating the spawning behavior of Pacific herring

The Cordova Times –

Every spring, researchers from the Alaska Department of Fish and Game and the Prince William Sound Science Center work together to estimate the spawning biomass of Pacific herring in Prince William Sound. This project is part of a greater effort by the Herring Research and Monitoring program to track the recovery of herring since its decline in 1993. Spawning biomass, the mass of the entire spawning population, is calculated using two methods in PWS. The original method of aerial surveys was improved upon when PWSSC researcher Jay Kirsch, along with John Wilcock, Gary Thomas, and Kevin Stokesbury came up with the hydroacoustic survey method in the early 1990s. Dick Thorne carried on the program for many years until Dr. Pete Rand took over. Since then, the program has used both methods: aerial surveys for their ability to cover a lot of ground and acoustic surveys to look deeper. The results tend to reinforce each other.

Acoustic surveys, headed up by PWSSC research ecologist Pete Rand, are usually done in two parts: first in the eastern sound including Ports Gravina and Fidalgo, and later in the western sound near Montague Island. About three or four nights of surveying are done in each region.

On a typical cruise, researchers spend the day looking for signs of herring in the area. At 30 to 40 meters deep, it’s not easy to see a school of herring from a boat, so predatory activity is the best indicator. Whales, sea lions, diving birds, gulls, and eagles all turn out for the feast when herring are around.

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