Changes in v-notch depth after molting in the American lobster, Homarus americanus Milne-Edwards, 1837 (Decapoda: Pleocyemata: Nephropidae)

The stocks of the American lobster, Homarus americanus Milne-Edwards, 1837, off Newfoundland and Labrador, Canada are heavily exploited and few females survive beyond their first molt into the fishery. V-notching is a mark-recapture, voluntary practice in the fishery but there are strict guidelines on the retention of any possible v-notched lobsters. In response to calls to relax the definition of what constitutes a v-notch, we developed a laboratory study to quantify the change in v-notch depth with molt and relate changes in carapace length to changes in potential fecundity. We collected 32 egg-bearing lobster from the field in June 2022. The females were v-notched, and the v-notch depth and carapace length were measured before and after molting. We found the v-notches were clearly visible after one molt. Under current restrictions, these females would have been protected during their following clutch, where potential fecundity increased by up to 68%; however, 18.5–88.9% could have been harvested if the definition of v-notched was relaxed. These findings suggest that current restrictions are more effective in the management of this heavily exploited fishery, and more widespread v-notching would boost the population’s reproductive potential and survival rate of newly recruited females.