Federal Aid to Fish Restoration Completion Report. Natural Lakes Investigations. Project No. F-160-R. Study 7015.

摘要

This study examined the production and consumption dynamics of the Spirit Lake fishery, with the goal of determining the carrying capacity of major piscivorous sport fish. Littoral fishes were sampled at night using beach seines. Population estimates of all major piscivores in Spirit Lake were made using standard mark-recapture techniques. Piscivore diets were assessed at monthly intervals during the ice-out season. Target species were captured with gillnets, seines, and electrofishing boats. We collected 142,179 fish from a total of 58 seine hauls. From these samples, we identified 25 species of fish inhibiting the lattoral zone in Spirit Lake. On average, we caught 11.5 species per seine haul, but the variation in species diversity was considerable from a low of 8 to a high of 18 species. Forage fish biomass also varied widely each year and month, from a low of 0.7 lbs/ac to a high of 39 lbs/ac. We examined the stomach contents of more than 3,000 fish. These samples contained over 41 recognizable prey taxa. Yellow perch were the primary fish consumed each year and accounted for 78% of the total fish consumed during our study. We also found the yellow perch to be the most abundant species, both in the lake and in the creel. Walleye and yellow perch were the dominant piscivores accounted for only a relatively small portion of fish consumed. Our data also showed biomass of yellow perch and other forage fish inhabiting the littoral zone appeared to be inadequate to meet the current or future forage requirements of the piscivore community. However, we did not estimate the biomass of forage fish in the limnetic zone, which may be a significant component of the total available, forage in the lake. Future investigations should include both the limnetic and littoral assemblages of forage fishes to give a complete picture of the supply and demand of forage fishes in Spirit Lake.