Sea Scallop Growth, Yield, and Reproduction
Understanding sea scallop biology represents the foundation of how we assess and manage the species and is a critical component of the research program. Data on sea scallop growth, yield, and reproduction are collected on all surveys and allow for the description of the population at varying spatial scales. The data we collect include:
- Length frequency distributions
- Meat weight
- Reproductive stage
- Meat quality
- Scallop shells for age determination
Shell Height and Meat Weight
Shell height and meat weight data are used to predict shell height meat weight relationships. We know that this relationship varies across time and space, and describing this relationship aids in identifying spatially explicit variation in yield that may need to be accounted for in the assessment and management of the resource. Mostly recently, low shell height meat weight relationships were observed in the Nantucket Lightship Access Area. The main driver behind this deviation is believed to be high scallop density. Shell height meat weight relationships are also used in biomass calculations to convert numbers of scallops to biomass estimates.
Length Frequency Distributions
Length frequency distributions are used to understand the size distribution of the population that is impacted by localized recruitment and fishing intensity. This information is used by managers to determine which areas can be opened to fishing and which areas should remain closed to protect juvenile sea scallops. Length data are collected during resource surveys for both the survey and commercial dredges.
Scallop Ageing
Like rings in a tree, the shell of a bivalve contains the history of its life. The VIMS Sea Scallop Research Program collects sea scallop shells to age in the lab in collaboration with the VIMS Molluscan Ecology Lab. The age and growth data collected from these shells allow us to evaluate differences in growth over the range of the resource to inform spatial management strategies. The team utilizes a variety of techniques to age scallops that include both external rings (visible rings on the surface of the shell) and internal rings on the shell hinge, known as the resilium.
Effects of Density
In 2013 and 2014, survey groups working in two spatial management areas (Elephant Trunk Flex in the Mid-Atlantic Bight and the Nantucket Lightship Acess Area on Georges Bank) detected high densities of newly settled sea scallops. These scallops have persisted at high densities and have exhibited growth below expectations.
To understand the impact of density on sea scallop growth, yield, and reproduction, the VIMS Sea Scallop Research Program began conducting quarterly sampling trips in both areas in 2018. The project collects length-frequency data and weights of adductor muscles, gonads, and other soft tissues. Other data collected include female gonads for egg quality determination and shell samples for ageing.