Demography of a Potential Shortnose Sturgeon Metapopulation in the Gulf of Maine: Recovery Implications

Recent advances in our understanding of shortnose sturgeon (Acipenser brevirostrum) ecology throughout the Gulf of Maine (GoM) suggest populations of these fish are more interconnected than previously thought.  Consequently, research focused on recovery of the species has shifted from a local river-by-river basis, to a more regional connectivity-driven metapopulation basis.  The complex nature of metapopulations places a priority on understanding demographic variation among component demes and their contributions to overall metapopulation productivity.  Our analyses of demography include information collected from over 4,000 shortnose sturgeon throughout the region beginning in 1977.  The demographic parameters of interest include spawning success, survival estimates, growth rate, frequency distributions of both length and weight, female specific length and weight, and proportion of late stage females.  This work is ongoing, but preliminary analyses indicate successful spawning in only one river system in the region (Kennebec River) and that late stage females have different length- weight relationships than the remainder of the population.  As work continues, clarification of local demography will facilitate understanding how local dynamics influence regional resilience of this potential metapopulation given the identification of higher degrees of population connectivity than were previously suspected.