Black Lake Salmon Studies

Owner: Chignik Regional Aquaculture Association (CRAA)

Dates: May 2013 through July 2014

Cost: Grant amount $107,800 + $57,184 (CRAA matching funds) = Total Project cost of $164,984

Description: This scientific study conducted sockeye salmon smolt monitoring from approximately May 1 through July 7 for two consecutive years, 2013 and 2014 to:

• Estimate the total number of emigrating sockeye salmon smolt by age and stock.

• Measure smolt migration timing and growth characteristics by age class.

• Monitor the physical characteristics of Black and Chignik lakes for changes

• Monitor Black and Chignik lakes for their nutrient availability and primary productivity

• Measure the zooplankton forage base available to the sockeye fry rearing in both lakes.

Purpose: Black Lake supports a population of sockeye salmon that are critically important for the residents of the Borough living in Chignik Lake, Chignik Lagoon, Chignik, Perryville, Ivanof Bay and also Port Heiden. Important uses include subsistence, commercial, sport, and personal use. Black Lake sockeye are a key species in the ecosystem and so are also important to bears and eagles and many other creatures. Black Lake has undergone significant and dramatically rapid natural habitat change in recent decades and has lost a significant proportion of its water volume which raises the specter that further declines in water volume could threaten the future viability of the Black Lake salmon system.

The Alaska Corps of Engineers, Alaska Department of Fish and Game, University of Washington School of Aquatic and Fishery Science, and Chignik Regional Aquaculture Association all concur that sockeye production in the Chignik lakes system at Black Lake is at serious risk should further erosion occur at the lake’s outlet. They have agreed that it is essential for physical and biological monitoring to be consistently conducted on an annual basis.

The project achieved its goals and the Borough funding was a key and vital factor in the sustainability of the project which CRAA has been able to continue into 2015 and 2016.

The rate of physical habitat change appears to have stabilized or slowed down significantly. Vigilant monitoring remains necessary but a reasonable and tentative hypothesis is that the physical degradation (shallowing of Black Lake via down-cutting at the mouth of Black Lake) has probably paused or ceased.

However, it seems likely that the habitat degradation that has already occurred may well have compromised the salmon producing capacity of the interacting Black Lake and Chignik Lake salmon system. This study is important for measuring the salmon populations response to those past habitat changes. These habitat changes include the estimated 20-40% volume reduction in Black Lake impacting the lake's available rearing habitat for juvenile sockeye fry and a shift in the forage-based strategy and timing of the Black Lake sockeye population so that now the stock is more aggressively competing with the Chignik Lake (late-run) stock by descending into Chignik Lake much earlier to compete for rearing habitat with the Chignik Lake population.

During 2014, a total of 4.3 million sockeye salmon smolt were estimated to have out-migrated – a very low number considering the range is 2 to 40 million and average is around 15 million. The smolt were of below-average body condition and zooplankton levels were lower than the previous year. While a single year’s results may not tell you much this kind of study gains statistical power when local stakeholders can share in the burden of maintaining a commitment to developing a long term data base of scientific data. With the data set we now have it seems reasonable to conclude that Black Lake sockeye will remain an important source of food and financial income for local Borough residents, but regrettably the long-term average run of the future will be prone to be less than the average season of the last four decades or so. Poor seasons will likely be poorer than in the past but standout excellent seasons will still come along from time to time but may well be less frequent and of lesser magnitude than if Black Lake had not experienced a dramatic volume loss.