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 potential new avenue for establishing smelt populations. Stockings of smelt fry into inland waters of Maine have already been undertaken by private organizations. We sought to assess the efficacy of stocking on supporting or supplementing a population.  One approach has focused on evaluating the effectiveness of marks applied to otoliths during the time the smelt reside at the hatchery. We tested three different techniques of applying marks including: thermal, oxyteracycline (OTC), and strontium marking to examine mark persistence and detectability over time. Fish were sacrificed and otoliths were examined for marks. Marking will help distinguish between stocked and wild smelt in waters with existing populations. 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: 13 to 47 hectares) with approximately 4,000 fish/hectare in mid-June 2013. The lakes were subsequently netted with a small trawl net throughout the summer, then with gill nets through the ice in attempt to recapture stocked smelt. Summer trawling captured other fish but no smelt.