STURGEON (2)

    IMG_2444 Keith-Bass

Recent paper abstracts:

Dunton, K.J., A. Jordaan, D.O. Conover, K.A. McKown, L.A. Bonacci and M.G. Frisk (2015). Marine distribution and habitat use of Atlantic Sturgeon (Acipenser oxyrinchus oxyrinchus) in New York leads to fisheries interactions and bycatch. Marine and Coastal Fisheries: Dynamics, Management, and Ecosystem Science 7:18–32, 2015.

Abstract: Population declines of Atlantic Sturgeon Acipenser oxyrinchus oxyrinchus prompted initial fisheries closures and an eventual endangered or threatened species listing across the U.S. portion of their range in 2012. Atlantic Sturgeon aggregations and migration routes along the coast of Long Island overlap with commercial fishing activities that may lead to incidental take in nondirected fisheries. Thus, understanding the distribution and movement of Atlantic Sturgeon in relation to commercial fisheries can help management agencies determine impacts and develop bycatch mitigation measures. Stratified random sampling and targeted bottom trawl surveys were used to identify the temporal and spatial use of marine habitat in New York waters. The majority of survey captures were restricted to depths of less than 15 m and known aggregation areas. During the aggregation periods (May, June, September, and October) in known aggregation areas, catches were an order of magnitude higher than in other areas and months of the year. Northeast Fisheries Observer Program bycatch data from 1989 to 2013 was
analyzed for the New York region and suggested that bycatch occurs within two main gear types: otter bottom trawls and sink gill nets. Trawling bycatch contained primarily subadult Atlantic Sturgeon and is highest during the Summer Flounder Paralichthys dentatus fishery in New York State waters. Trawling overlaps spatially and temporally with identified Atlantic Sturgeon aggregation areas, while bycatch in gill nets targeted adult fish farther offshore in federal waters. Bycatch in these fisheries may be a regional threat to recovery, and spatial and temporal closures, gear modifications, or other bycatch reduction techniques are suggested to protect aggregating and migrating fish.

Genetic diversity and effective number of breeders of Atlantic sturgeon, Acipenser oxyrhinchus oxyrhinchus. O’Leary, Shannon J., Dunton, Keith J, King, Tim L., Frisk, Michael G.; Chapman, Demian D. (2014). Conservation Genetics.

Abstract: Juvenile Atlantic sturgeon (Acipenser oxyrhinchus oxyrhinchus) forming aggregations at coastal sites in the mid-Atlantic Bight were objected to a mixed stock analysis (MSA) and individual-based assignment using twelve microsatellite loci. We confirmed earlier findings from an analysis of kitochondrial DNA that three river spawning populations (Hudson, James and Delaware Rivers) are the primary sources of these particular marine aggregations. Of the 460 individuals sampled 322, 36 and 47 were assigned to the Hudson, James and Delaware Rivers, respectively. MSA estimated that the New York Bight Distinct Population Segment (Hudson River and Delaware River) contributed 83–90 % of individuals to the marine aggregations and the Chesapeake (James River) and Southeast Distinct Population Segments contributed 5.5–11 %. Mean M-ratios were lower than expected at equilibrium in all three rivers (Delaware = 0.726, Hudson = 0.748, James = 0.664), indicative of genetic bottlenecks affecting all three spawning populations. Further, there were low but detectable levels of inbreeding in all three rivers populations. Effective population size (Ne) was estimated for three populations: Hudson River (172–230 individuals), James River (40–100 individuals) and Delaware River (75–186 individuals). Despite these issues, simulations based on life-history information and the Ne estimates suggest that if ongoing management Measures are effective, contemporary levels of Population genetic diversity are likely to be retained over the next century.