Bridge-crossing study finds there's abundant sealife in Knik Arm

Scientists say it's still too early to know whether construction will hurt the area's whales or fish

Posted: Monday, April 11, 2005

ANCHORAGE - The Knik Arm contains a menagerie of marine life hidden in the Inlet's silt-saturated tides, according to preliminary reports on a proposed bridge over the area.

Scientists surveying beluga whales and fish during studies of the proposed crossing found 14 species of fish plus nine kinds of shrimp and the upper Inlet's sole clam species.

"It certainly begs the question that this murky water is actually more productive than we think," said marine mammal biologist Mike Williams, with LGL Alaska Research Associates. "You look out there, and it's not this clear, blue water, and you think there's not very much alive out there. But there are belugas there for a good three months, and when guys throw nets out, they find a lot of fish."

The reports covered work done in July through November. The studies will continue through midsummer. Scientists say it's too early to know whether building a bridge linking Anchorage with the Matanuska-Susitna Borough could cause problems for Knik's whales or fish.

The information already in hand, however, may help sort out what can be done to help Cook Inlet's depleted population of whales recover from a 1990s crash, said beluga management biologist Barbara Mahoney, with the National Marine fisheries Service. A draft conservation plan has been completed, with a final version due in the fall.

"What they're seeing kind of confirms the information that we've collected on the tagging data and our observations in the fall," Mahoney said. "That the whales still continue to use Knik Arm basically all year long."

The reports are among studies launched in 2004 to gauge marine life, currents, sediment, contaminant sources, water quality and engineering issues raised by bridging Knik Arm. Commissioned by the Knik Arm Bridge and Toll Authority and coordinated by HDR Alaska, the work is part of a comprehensive environmental investigation.

Scientists with Pentec Environmental - including Jon Houghton - had already surveyed the area in May and June of 1983 as part of an earlier round of Knik Arm crossing analysis. This time, Houghton and his team used beach seines at nine stations to collect 1,048 fish from 14 species between July and November. The catch included about 200 juvenile and adult salmon. They also took samples with other methods.

"The amount of juvenile salmon there in late summer and early fall into early winter was surprising," Houghton said. "

To find out what belugas were doing, Williams led a team that monitored whale activity from observation posts along Knik Arm and then cruised the Inlet in a small boat. Up to 100 whales appeared to spend the season in Knik Arm above Anchorage.

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