View of the lower Chilkat River where it flows into Chilkat Inlet and the Lynn Canal, where chum fry rear in near shore areas.

NSRAA’s field project near Haines, Alaska operates primarily in the Chilkat and Klehini River valleys. Due to these valley’s recent glaciation and steepness, the rivers in them flow as braided, constantly shifting channels that offer high quality, yet often only temporary chum spawning habitat. To provide a measure of consistency in the return of chum salmon to the commercial fishery in Lynn Canal, NSRAA enhances chum populations through construction and maintenance of spawning channels and incubation of chum eggs in streamside incubators.

NSRAA’s chum enhancement projects near Haines include Herman and 24-mile spawning channels as well as streamside incubation sites at Herman channel and at 17 and 31-mile of the Haines Highways. Herman spawning channel and incubation site and the 31-mile mile incubation site enhance Klehini River chum salmon that typically return as adults around the first week of September. The 24-mile spawning channel and the 17-mile incubation site enhance Chilkat river chum salmon that return about a month later. By working with both runs of chum salmon, we ensure enhanced chum are available to fishermen during Lynn Canal commercial fishery openings both early and late in the season.

Projections are that through natural spawning in Herman spawning channel and incubation of eggs at the Herman incubation boxes two adult chum salmon are produced for every one that returns to spawn. With recent increases in the number of eggs incubated, this ratio has increased to 5 to 1. Since its construction in 1989, escapement to Herman spawning channel has averaged 4,500; fecundity averages 2,500 eggs per female. A portion of the returning fish are captured in a trap at the downstream end of the channel and used for broodstock that is seeded in the incubators. When the eggtake goal of 1.6 million eggs is met, the trap is removed and the fish are allowed to spawn in the channel.

Herman spawning channel.		Fish trap on Herman spawning channel.

Egg to fry survival in the spawning channel averages 5 to 15 percent while survival to fry in the incubation boxes averages 98 percent. For comparison, egg to fry survival on local rivers is around 2 to 3 percent. When fry in the spawning channel gravels and incubation boxes reach the alevin stage and “button up” their yolk sacs, they are on their own in their downstream migration to rear in near shore areas of the Lynn Canal.

Incubation boxes at Herman spawning channel		Seeding chum eggs in incubation boxes.

When adult chum returns to Herman spawning channel are in excess of what can be seeded in incubators and spawned in the channel without a high degree of superimposition of redds, excess broodstock is transported to and seeded in incubators at 31-mile, where the permitted capacity is 800 thousand eggs. Otherwise, broodstock for this site is collected by beach seining the Klehini River. The Alaska Department of Fish and Game permits NSRAA to collect broodstock from local rivers within a three mile radius of the incubation sites.

Incubation boxes at the 31-mile site.		Beach seining on the Klehini River.

Constructed in 1983, the 24-mile spawning channel has provided Chilkat River chum high quality spawning habitat and allowed broodstock collection for the 17-mile incubation site. Partly a victim of its own success, consistently high returns to the channel for all except the last 5 years have allowed spawners to mobilize nearly all spawnable gravels from the channel, leaving only a base of cobbles too large for redd construction. A 2005 Alaska Legislature grant for spawning channels in the Chilkat and Klehini River Valleys is funding rejuvenation of spawning gravels in the 24-mile channel, thus chum returns to and production from this site should restore to the historic annual average range of 5 to 10 thousand fish in the coming years. Until then, broodstock is collected for the 17-mile incubation site by beach seining the Chilkat River. The Legislature grant that is funding rejuvenation of the 24-mile channel is also funding construction of three new spawning channels that will be tributaries to the Chilkat River; completion of these new channels is targeted for 2008.

24-mile spawning channel.		Broodstock collection on the Chilkat River.

The incubation site at 17-mile utilizes ample high quality groundwater that flows out from under the Takshanuk Mountains to incubate its permitted capacity of 1.2 million eggs. As at our other incubation sites, survival of enhanced chum has only ever been projected by subtracting the number of dead eggs in the boxes post-migration from the known number of eggs that were seeded. At the 17-mile site beginning with brood year 2005, projections will be tested by thermal marking chum otoliths in two of the four incubation boxes at this site. In 2010 when the first marked brood year return is complete, the percent of thermal marked otoliths recovered will indicate the contribution of enhanced chum to the commercial fishery in Lynn Canal and the escapement to the Chilkat River.

Water source for incubation boxes at 17-mile.		Incubation boxes and thermal marker at 17-mile.