My Turn: Kensington mine is a threat to Berners Bay fish habitat

Posted: Thursday, September 29, 2005

The Sept. 16 "My Turn" column explains how the Corps of Engineers violated the federal Clean Water Act by permitting the Kensington Mine to dump 4.5 million tons of tailings into Lower Slate Lake above Berners Bay. The article provides a rational explanation of why conservationists have taken the violation to court.

Another disturbing aspect of the mine operation that is not the focus of litigation is its potentially serious and irreversible harm to fish resources in Berners Bay and Lynn Canal. The largely undisturbed bay and its tributary rivers support five species of salmon, Dungeness and tanner crab, halibut and cod. The bay provides the last significant herring spawning and rearing habitat in lower Lynn Canal.

Incremental, cumulative mine-related impacts are expected to permanently degrade the nearshore ecosystem upon which all aquatic life in Berners Bay depends. Shoreline facilities and increased vessel traffic are expected to disrupt migration patterns and alter current patterns that determine predator-prey distribution, spawning habitat, immature fish survival and critical freshwater-salinity gradients. Slow and chronic releases of hydrocarbons are expected to disrupt fish reproduction.

These impacts would extend far beyond Berners Bay because commercially important fish and their prey move freely between the bay, the rest of Lynn Canal and Icy Strait. These populations support the region's commercial gillnet, seine, and troll fishermen, as well as sport and subsistence users.

Studies in the 1980s indicate that Lynn Canal's east shore is a critical migration corridor for juvenile salmon migrating from the rich spawning grounds in northern Lynn Canal. Juveniles stay close to shore to feed and avoid predation. Some fish follow the beach around Point St. Mary into Berners Bay. It is well documented that Chilkat River coho smolt migrate to sea, then overwinter in Berners River and leave the following spring.

Berners Bay herring and eulachon are important to juvenile salmon. Juvenile salmon migration coincides with the hatching of herring, and fish prey in general comprise 30 to 75 percent of their diet.

In 2004, an Alaska Department of Fish and Game biologist stated that the Lynn Canal herring stock collapsed in 1982 and has not recovered. He said that overfishing and Auke Bay habitat degradation are thought to be the main contributing factors. Developing a mine-related marine facility at Cascade Point is likely to impact herring. Continued encroachment on shoreline spawning habitat could collapse the area's herring resource and the amount of food available to Lynn Canal juvenile salmon.

Immature kings feed throughout Lynn Canal and depend on herring and eulachon. Herring and eulachon also feed mature kings and cohos moving through Icy Strait toward the many spawning rivers and streams in Lynn Canal. Adult king, coho, chum and pink salmon returning to spawn in northern Lynn Canal feed on aquatic resources produced in Berners Bay. Berners River coho smolt produce adults caught in the Chilkat River. The bay's plankton-rich water feeds migrating sockeye salmon.

Commercial gillnetting in Lynn Canal also depends on summer chum returning to hatchery release sites at Amalga and Boat harbors. Primary fishing for summer chum lies between the latitude of Little Island and Point Bridget, the southern point of Berners Bay. Sockeye destined for Berners Bay migrate through this area when chum are harvested.

ADF&G must manage all salmon fisheries to ensure wild salmon escapement in numbers sufficient to sustain them. The bay is the first estuarine environment juvenile sockeye encounter. If industrial development in the bay negatively impacts wild sockeye, ADF&G may need to close the lower Lynn Canal summer chum fishery to protect it. Closure would affect fishermen, nonprofits that produce chum, and processors who buy gillnetted chum and sockeye.

ADF&G may also need to limit commercial trolling to protect Berners Bay coho from overharvest. Coho depend on a healthy estuary and the fish prey it produces. A collapse of herring and eulachon runs could dramatically impact coho.

Agencies can speculate that the Kensington Mine will not impact Lynn Canal fisheries; however, events commonly unfold differently than government and industry people hope. Consequences for complex biological systems like Berners Bay-Lynn Canal can be serious and irreversible. To risk sustainable Lynn Canal fisheries for short-term economic returns from the Kensington Mine would be irresponsible.

• Bruce Baker is a natural resource consultant, conservationist and retired deputy director of the Alaska Department of Fish and Game's Habitat Division.

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