February 15-18, 2009 Washington State Convention Center Seattle ...

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NUTRITIONAL STUDIES ADVANCING ATLANTIC STURGEON BROODSTOCK
DEVELOPMENT AND RESTORATION SCIENCE
Andrew M. Lazur* and Erin Markin
Horn Point Laboratory
University of Maryland Center for Environmental Science
Cambridge, MD 21613 USA
alazur@hpl.umces.edu
One facet of a collaborative Chesapeake Bay Atlantic sturgeon restoration program involves studies related to sturgeon nutrition
and feeding management practices. Feed training of wild-caught fish is being evaluated to develop feeding protocols in
support of establishing a captive broodstock population. Other studies are evaluating fatty acid enrichment of live larval foods
and pre-release weaning assessment, to advance the technologies applicable to future replenishment research. A summary of
findings and implications for future research will be summarized.
Two feed training methods, force feeding and passive introduction of natural foods, were evaluated. After initial introduction
of natural foods, varied ratios of natural and commercial pellets in several forms were used to transition them to a diet consisting
entirely of commercial pellets. Fifty-eight of sixty-seven fish (85%) have been successfully trained to a commercial pellet
during year one of this study. Seven fish did not train to natural foods, while two fish transitioned to various passive diets but
did not survive until acceptance of commercial diet, most likely due to excessive weight loss. Both methods were successful in
training sturgeon, however, force feeding was observed to be stressful and unnecessary due to the success achieved with various
passive feeding regimes. After successful acceptance of commercial diets, fish were observed to be lean. In addition, the
inability to obtain viable sperm from successfully feed trained fish indicates possible holding stress and nutritional deficiencies
and warrants further studies.
Fatty acid enrichment of Artemia was conducted using three commercially available algal based enrichments (10% DHA, 10%
DHA and astaxanthin, and ARA) and fed to eight day old Atlantic sturgeon fry. Survival ranged from 72-99%. Mean weights
were 0.27, 0.26, 0.24, and 0.17 grams for the ARA, control, 10% DHA and astaxanthin, and 10% DHA respectively. Though
some difference in growth was observed between enrichments, growth in the control or non-enriched treatments was similar to
two of the enrichments supporting that enrichment is not necessary.
The ability of hatchery-reared fish to accept natural foods in released sites is an important question in developing replenishment
plans. To evaluate this, a brackish water closed pond study evaluated two juvenile year classes’ ability to adapt to natural foods.
Fish were PIT tagged, divided into two treatments: weaning from commercial diet to natural foods prior to release, and released
without weaning; and stocked into a 0.2 hectare pond supplied with natural foods. Significantly greater specific growth rate
was observed in the weaned fish of both year classes suggesting a benefit of weaning. Future studies will involve younger fish
in freshwater environments.