Fish finder

MAT-SU — A new study by the Alaska Department of Fish and Game promises to give biologists a better understanding of chum and coho salmon spawning patterns and distribution in the Susitna River drainage.

Using a fish wheel 20 miles upstream from the mouth of the Susitna River, Fish and Game personnel tagged silvers and chums with radio transmitters. The fish are released back into the river, and their movements are followed through the drainage, said lead research biologist Rick Merizon.

“The transmitters have a life of 80 to 90 days and are emitting a signal we can locate at any time,” Merizon said, adding there are two ways to track the fish once tagged.

First, Fish and Game has two autonomous, self-powered tracking stations, one on the Susitna and one on the Yentna.

“A radio receiver picks up the signal and tracks when and how quickly that fish passed that tower,” Merizon said. “That can give us a vague sense of distribution and speed.”

The other method of tracking is via antenna mounted to a Fish and Game aircraft. They fly the length of the rivers and register a hit when they pass a tagged fish.

“This gives us a much finer scale distribution of where those fish are located,” Merizon said. “We can track them probably within a mile.”

He admits this is not the most precise measurement, but it should give them a general idea about where the chum and coho spawn. The study will continue for three years, and with a fair amount of statistical analysis, biologists should be able to apply their findings to a larger fish population.

“If there are locations over the course of several years that have large concentrations of radio tags, we might make some conclusions from that,” Merizon said.

These conclusions are important for a number of reasons, he said. First, Fish and Game does not have a strong understanding of where chum and coho spawn in the Susitna drainage. After the study, Merizon said, “we’ll have a baseline of where things currently are right now before any further development takes place.”

Also, the study may lead to new candidates for the anadromous waters catalogue. This is a database of waters deemed important habitat for fish that migrate from rivers and lakes to the ocean and back. The classification comes with special regulations and protections.

But, in the end, the study is really about conservation, he said.

“The goal is to better protect the resource by having a better understanding of what areas of the drainage are important to chum and coho,” Merizan said.

Contact Todd L. Disher at todd.disher@frontiersman.com or 352-2252.