Trends in mortality and evaluation of management measures for American shad as they apply to the Connecticut River stock

Amendment 3 to the ASMFC Interstate Fishery Management Plan for American shad requires coast-wide commercial and recreational moratoriums by 2013 in all waters, allowing only catch and release recreational fisheries.  To remain open, States or jurisdictions must submit a sustainability plan for approval which demonstrates the fishery(ies) will not diminish potential future stock reproduction or recruitment.  We present Connecticut River shad data and environmental parameters which were used to model populations.  A regionally calculated mortality index (Z30 = 0.98) recommended for New England stocks is a combination of a F value of 0.60 and a M value of 0.38 (ASMFC 2007).  The Connecticut River American shad stock size declined by 50% since the mid-1990’s, but fishing effort and catch steadily decreased while natural mortality systematically increased.  Fishing mortality rates calculated for the times series (1966-2008) did not approach or exceed the 0.60 overfishing value.  In contrast, the natural mortality benchmark of 0.38 was exceeded every year.  The systematic increase in M, and thus Z was correlated to predator abundance and post-spawning mortality.  Simulation modeling exercises demonstrate that a shad fishery moratorium will provide little if any leverage for stock rebuilding.