Abstract
Adjustments to rearing practices should be justified with increases in production, stocking success, or angler satisfaction. Largemouth bass (Micropterus salmoides) production was assessed between hatchery ponds where fish were restricted to an invertebrate diet or received supplemental fathead minnow (Pimephales promelas) forage during 2015. At harvest, age-0 bass yield was 4.5 times greater and average fish length was 38 mm longer, in the pond that received fathead minnow. In 2016, a second study evaluated the timing of minnow supplementation that included earlier stockings of small fathead minnow (30 mm) minnows. With earlier supplementation, bass yield was 2.3 times greater and fish averaged 14 mm longer at harvest. Bass survival was approximately 38% higher during 2015 when supplementation occurred and 25% higher during 2016 when minnow supplementation began earlier. Our findings show invertebrate forage was probably limiting bass production in hatchery ponds and supplementing with appropriately-sized fathead minnows increased age-0, largemouth bass production.
Highlights
Largemouth bass (Micropterus salmoides) fisheries provide important recreational opportunities and associated economic benefits in North America [1]
Largemouth bass (Micropterus salmoides) production was assessed between hatchery ponds where fish were restricted to an invertebrate diet or received supplemental fathead minnow (Pimephales promelas) forage during 2015
Our findings show invertebrate forage was probably limiting bass production in hatchery ponds and supplementing with appropriately-sized fathead minnows increased age-0, largemouth bass production
Summary
Largemouth bass (Micropterus salmoides) fisheries provide important recreational opportunities and associated economic benefits in North America [1]. A variety of rearing techniques exist to enhance growth and size-at-stocking of largemouth bass that include, reducing fish densities [3], increasing forage by providing fathead minnow (Pimephales promelas) [4], and (or) transferring bass to tanks and converting fish to pelleted diets [5] [6]. In South Dakota, fathead minnows are an abundant resource [7] that have been used to supplement aquatic invertebrate prey during the extensive rearing phase of largemouth bass in hatchery ponds (Personal Communication, Jerry Broughton, Hatchery Manager). Stocking of fathead minnows during the early rearing phase may provide little benefit to age-0 bass growth, if invertebrate prey are abundant and (or) the ratio of minnow-length to bass-length is too great (i.e., gape limitation). We compared numbers of largemouth bass produced with or without supplemental minnow stockings in the initial study, and we examined early and late-season minnow stockings compared to late-season only, minnow stockings
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