Virginia Institute of Marine Science
Marine Advisory Program (MAP)
Marine Resource Report No. 2022-02
If the current sea scallop fishery is well managed with a Catch At Size Analysis (CASA) length structured model, then why bother with an age based assessment? The success of the CASA based approach, in conjunction with management measures, is demonstrated by the development of the scallop fishery over the past two decades to its current status as the one of the most valuable fisheries on the Atlantic coast of the United States (NOAA, 2021). But, even the best length-based model can be improved by the addition of age data. An age-based model calibrates a length-based model, including a description as to whether or not the age-length relationship is constant across time and space throughout the exploited range of the fishery. It also improves description of recruitment in species where age estimation for small/young individuals is difficult, and description of mortality where age estimation of large/old individuals is difficult (both are the current case for sea scallops). The project described here also improves on the current status quo for age estimation in that it allows the use of a full range of sizes collected individuals, rather than just larger individuals, in age estimation, and is not compromised where external shell signatures, the current base for scallop age estimation, are eroded and difficult to read. In short, an age-based assessment would provide tools to the scallop assessment that are currently limited in certain aspects.
Sea scallop fishery, age determination
Submitted to: National Marine Fisheries Service, Northeast Fisheries Science Center.
Mann, R. L., Rudders, D., Roman, S., Southworth, M., & Clark, K. R. (2022) Age Based Assessment in the Sea Scallop Placopecten magellanicus: A Pilot Study - Final Report. Marine Resource Report No. 2022-02. Virginia Institute of Marine Science, William & Mary. https://doi.org/10.25773/vacb-7505