Reproductive success of hatchery- and natural-spawning sockeye salmon, Auke Creek, Alaska

Evaluating salmon hatchery supplementation programs requires assessing not only program objectives but identifying potential risks to wild populations as well. Such evaluations can be hampered by difficulty in distinguishing between hatchery- and wild-born returning adults. Here, we conducted three years (2011–2013) of experimental hatchery supplementation of sockeye salmon in Auke Lake, Juneau, Alaska where a permanent weir allows sampling and genotyping of every returning adult (2008–2019). We identified both hatchery- and wild-born returning adults with parentage assignment, quantified the productivity (adult offspring/spawner) of hatchery spawners relative to that of wild spawners, and compared run timing, age, and size at age between hatchery- and wild-born adults. Hatchery-spawning females produced approximately six to 50 times more returning adults than did naturally spawning females. Supplementation had no discernable effect on run timing and limited consequences for size at age..., From 2008 to 2019, each returning adult sockeye salmon that ascended to Auke Lake was captured at the Auke Creek weir, on the outlet of Auke Lake, and identified based on the appearance of the snout and vent as a female, regular-sized male, or “jack” (precocious male ≤ 400 mm mid-eye to fork length) male.  Each salmon had an axillary process removed and stored in 95% ethanol for subsequent DNA extraction and genotyping. Fish were sampled every day during the run, and all were sampled for genotypes. A sub-sample (~12% of the total run) was sampled each year for age (from scales) and length (mid-eye to fork) data. Sampling was intended to be representative across the entire run.
Over three successive years (2011–2013), sockeye salmon were artificially spawned and their progeny were reared to the early fry stage prior to release into Auke Lake. A small number of adults (<50 per year, averaging 2.5% of the total run annually) were captured at the weir, retained for broodstock, held at th..., , # Reproductive success of hatchery- and natural-spawning sockeye salmon, Auke Creek, Alaska

This dataset consists of phenotypic (sex and adult return migration timing for all sampled fish; length and age for a subsample) and genotypic data on all adult sockeye salmon returning to Auke Lake, Juneau, Alaska, from 2008 to 2019. Genetic data were used to assign adult offpsring to parents, and from those assignments calculate relative productivity, or the average number of returning adult offspring produced by hatchery spawners relative to that of wild spawners over three brood years (2011-2013). These data were also used to determine if phenotypes of hatchery-born fish differed from those born in the wild. Hatchery spawning was successful, with captive spawners producing between 6 to ~50 x the number of returning offspring than wild spawners. Hatchery-born fish did not differ from wild-born fish in return timing or size at age, but they tended to be younger on average. 

## Description o...