Primary Investigators: Pedro A. Quijon, Sophie St-Hilaire

The growth of European green crab populations threatens the sustainability of healthy aquatic systems, multiple shellfish species, and the livelihood of fishing communities that rely on these resources. There is an urgent need for novel mitigation measures to help sustain healthy shellfish and provide alternative sources of income to fishermen. An imminent green crab fishery addresses the need for mitigation but its viability over time is uncertain due to the lack of a competitive market for the harvested crabs. One attractive option is the development of a soft-shell green crab product similar to the existing and successful soft-shell crab industry in regions of Italy and the US. These industries rely on the identification and harvesting of “soft” moulting crabs that sell for over €40 / kg.

The goals of this project are to explore the most promising methods for identifying moulting green crabs in PEI and to apply the pre-moulting sorting and holding techniques successfully used in Europe to the green crabs found in PEI. Through a combination of information gathering from areas where a soft-shell green crab fishery already exists and field studies to be conducted in PEI, we expect to lay the foundation for an industry that will address both mitigation of a growing ecological problem and the sustainability of healthy shellfish resources.

We hypothesize that subtle color changes, differences in weight-to-length ratios, and changes in the inter-carapace space can be used to identify different pre-moulting stages of green crabs. We also hypothesize that, like the Italians, we can utilize the natural spring moulting window to harvest a high proportion of soft-shell green crabs.

Specific objectives include: i) Integration of information gathered in areas with established soft-shell crab fisheries to the PEI setting; ii) Assessment of key body features and conditions as indicators of moulting in field-held green crabs, and; iii) Assessment of muscle-to-carapace ratio prior to moulting as a driver of moulting.