Virginia Institute of Marine Science
Marine Advisory Services (MAS)
Marine Resource Report No. 2018-04
Natural mortality, growth and movement are fundamental processes critical to understanding and describing population dynamics. These population characteristics not only inform and influence stock assessment models, but are also highly relevant with respect to the design and implementation of management strategies to meet fishery objectives. For many species, including sea scallops, these population parameters are difficult to measure due to the nature of the habitats inhabited and as a result, minimal information is often available. In many cases, what estimates do exist are highly uncertain as a result of both observation and process error. The uncertainty of these parameters is exacerbated for a species such as the sea scallop whose life history strategy is predicated on large, episodic recruitment events where natural mortality and growth may vary as a function of animal density.
In 2015, resource surveys by the Virginia Institute of Marine Science (VIMS) and others observed what appeared to be an exceptionally large incoming year class of sea scallops throughout the Mid Atlantic Bight (MAB), with the locus of the event located in the Elephant Trunk Closed Area (ETCA). At the time of first encounter, these animals were roughly two years old and the scale of the event in terms of the spatial extent and magnitude was extensive. Multiple surveys delineated the distribution of the event and confirmed the enormous magnitude of scallops in the area, but critical questions remained. What is the survival rate of the unfished cohort (i.e. natural mortality rate)? What is their growth rate? Would the scallops survive? Would they grow at rates similar to what was expected? Would the animals move either inshore or offshore to a different habitat? To address these questions, we conducted a sea scallop mark-recapture study in the area of newly recruited scallops in the ETCA.
Submitted to: National Marine Fisheries Service Northeast Fisheries Science Center
Sea scallop fishery
Rudders, D., Hoenig, J., & Roman, S. (2018) Scallop Mark-Recapture to Estimate Density Dependent Natural Mortality and Growth : Final Report. Marine Resource Report No. 2018-04. Virginia Institute of Marine Science, William & Mary. https://doi.org/10.25773/p71r-mw86