Bristol Bay, Alaska is home to one of the largest runs of sockeye salmon in the world, with numbers surpassing 40 million fish in some years. In large part, this dramatic productivity is attributed to appropriate and high-quality habitat for this species. Like other anadromous Pacific salmonids, sockeye salmon spawn in freshwater streams in late summer and fall, burying their eggs in gravel, where the embryos develop throughout the winter months. In the spring, newly hatched fish, or fry, emerge from the stream bed after taking up their nutrient-rich yolk sac, and may either spend a period of weeks to years in the stream environment (in the case of coho and Chinook salmon) or may rapidly leave their spawning habitat. Pink and chum salmon fry travel quickly to an estuary or marine environment, while the majority of sockeye take a unique strategy and spend a year or more feeding and growing in a lake system.
After several years in the ocean, adult salmon return to their natal streams or rivers to spawn. In Bristol Bay and other systems with a fishery, up to 70% of these returning fish are captured in nets near the mouth of large river systems. The fishery is supported by production of millions of sockeye salmon fry emerging each year in lake and river systems such as the Wood River lakes, where I’m located for another year of field research. This system, along with two others in Alaska, has been the home for long-term research conducted by the University of Washington’s Alaska Salmon Program, known as the Fisheries Research Institute when it was founded in 1948.
Sockeye salmon dominate this system of interconnected lakes, and the Alaska Salmon Program has been sampling nearly every freshwater life history stage of this fish for many decades. Beach seine efforts capture young of year sockeye fry and other resident fish in the lake, including three- and ninespine sticklebacks, two sculpin species, whitefish, and young of year char. Outmigrating smolts are sampled where the lake begins to turn into the river, down which these silvery, finger-sized fish travel to reach Bristol Bay. For many years, the Program has been modeling the projected number of fish to return to each major river system, corresponding to each fishing district, in Bristol Bay. Once adult fish enter the lake, mature, and begin moving into streams to spawn, regular surveys record number of adult fish in each stream and ratio of males to females. Otoliths, an ear bone of the fish which records patterns of growth similar to a tree ring, are removed from a subset of fish from each stream to determine age composition of returning adults, used in part to predict future runs. Other past and ongoing work by ASP faculty and graduate students has addressed the importance of salmon to the rest of the ecosystem, and the benefits that this yearly pulse of nutrients confers to riparian plants, bears, birds, and resident fish such as rainbow trout and arctic char.
The English translation of Aleknagik is “wrong way home”. This lake, and the village of Aleknagik located at the outlet, is where you end up if you badly navigate and make a left turn to travel up the Wood River instead of following the Nushagak River inland. This is my third summer on this seasonally dynamic lake and, increasingly so every year, it feels more like home and less like I’ve ever left when I arrive back in camp for another summer.