Nutritional Studies Advancing Atlantic Sturgeon (Acipenser oxyrinchus) Broodstock Development and Restoration Science Andrew Lazur And Erin Markin, University of Maryland, Center for Environmental Science
900 Atlantic Sturgeon Harvest Thousands of pounds 800 700 600 500 400 300 Why have sturgeon not recovered? Biological reasons Slow to mature Intermittent spawning Environmental reasons Habitat loss Water quality Human interactions What can we do? Reduce mortality Bycatch Harvest - Ship strikes Conduct Test releasesstock enhancement Restore essential habitat 200 100 Sturgeon < 4 illegalized 0 1880 1890 1901 1918 1925 1930 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 1974: Va. moratorium 1998: ASMFC moratorium Peak Clear-Cut Recruitment Failure Harvest
Mid Atlantic Sturgeon Restoration Partnership Virginia Waterman Association Conduct research test releases to determine: size of fish, stocking location, seasons, survival, and recruitment potential Continue development of broodstock population and management plan Build on cryopreservation technology Investigate effect of broodstock diet on gamete quality Develop habitat assessment techniques to identify target tributaries Investigate need for streamside culture facilities to insure imprinting Investigate DNA markers to ID hatchery fish Adapt other new marking technologies for use in Atlantic sturgeon Continue feed training work, especially on larger fish Investigate larval live food techniques Evaluate effect of pre-release weaning
Feed Training of Atlantic Sturgeon Broodstock Initial step in developing an Atlantic sturgeon restoration program Passive vs. force feeding methods Next phase- larval feeding
Training wild -caught sturgeon onto feed Forced feeding or passive techniques
Feed Training Study Preliminary Results
Summary of Passive Feed Training Wild Caught Atlantic Sturgeon 10 Diets tired using natural foods initially then mixed with commercial diet in various formulations: gel diet, soft pellet, gradual natural/commercial transition diets 92% success in training sub adult fish onto commercial diet 80% success for large fish Released three large fish due to continued weight loss
Larval Live Food Enrichment Study Treatments: Control - Unenriched Artemia to CTS ARA Enriched Artemia to CTS DHA Enriched Artemia Astaxanthin Enriched Artemia CTS Conversion Threshold Size (34 mm; 0.18 gram) (Mohler, 2001) Conclusions: Fatty acid enrichment unnecessary; fast growth: 6 inch size in 12 weeks; 78-99% survival
Pre-release Feed Weaning Study 0.2 ha. brackishwater pond 2006 and 2007 year class fish Growth and lavage every month Prey analysis
Prey Consumption Stomach analysis by lavage showed that fish in all treatments foraged on natural foods. Lavage analysis for the 28 and 54 day samplings showed that fish of all treatments had consumed more grass shrimp Palaomontes pugio than Chronomid larvae and polychaete worms Neathes spp respectively. At the 84 day final harvest stomach contents fully collected to determine food preference. Results showed, in order of prevalence, grass shrimp, Chronomid larvae, polychaetes, goby Gobiosoma spp., and mud crab Rhithropanopeus harrisii.
Performance - Specific Growth Rate Sampling 2006 YC Control 2006 YC Weaned 2007 YC Control 2007 YC Weaned 28 days 0 0-0.166 a 1.998 ab 54 days -2.995-2.179 0.144 ab 1.036 abc 84 days -2.503-2.348 0.090 a 0.221 ab Survival (%) 80.0 90.0 79.3 90.0 Significance among row values designated by different letters
Atlantic Sturgeon Specific Growth Rate 2 1 0-1 -2 2006 Control 2006 Weaned 2007 Control 2007 Weaned -3 29 days 55 days 84 days
Conclusions Released fish consumed a variety of natural foods primarily grass shrimp Weaned fish demonstrated greater growth Greater specific growth rate observed in younger fish Natural food supply and variety in pond may be limiting growth Longer term growth of younger fish needed and freshwater growth and prey analysis