Assessment of a Hatchery Based Rainbow Smelt Supplementation Effort

Rainbow smelt are an important part of coldwater fish communities in Maine lakes. The successful development of hatchery cultured smelt has opened a new avenue for supplementing smelt populations. We sought to assess the efficacy of stocking on supplementing a population.  One approach has focused on evaluating the effectiveness of marks applied to otoliths during incubation at the hatchery. A second approach has focused on the survival of smelt during the first year after stocking. We stocked four lakes in central Maine (size range: 12 to 44 hectares) at a low density (4,000 fish/hectare) in 2013 and two lakes at a high density (30,000 fish/hectare) in 2014. The lakes were subsequently netted with a small trawl net throughout the summer to recapture stocked smelt and estimate abundance and survival throughout the summer. Zooplankton samples were collected along with fish trawls to correlate spatial distribution of young smelt with zooplankton species composition and density. Trawling in 2013 recaptured 0 smelt in all four lakes, in 2014 we recaptured 2 smelt in one lake and >1,800 smelt including stocked and wild in the other. These data suggest that the results of larval smelt stocking are variable at best and ineffective at worst.