Size at Maturity

From May to June 2025, a collaborative project took place at the Bedford Institute of Oceanography to study the size at which female lobsters reach sexual maturity. The size at 50% maturity (SoM50%) is a key measure for lobster stock assessment and helps guide management decisions like the minimum legal harvest size. Maturity varies by Lobster Fishing Area (LFA) and can change over time due to environmental shifts and fishing pressure. Updated data are essential to support sustainable management.

The project brought together fishermen’s associations, research organizations, and scientists to investigate female lobster maturity in LFAs 31B, 32, 34, and 36. Sampling took place during active fishing seasons, using “ships of opportunity” to collect lobsters representing different size classes. This collaboration  strengthened sampling capacity, reduced costs, and improved coordination among organizations. 

In the lab, researchers examined each lobster’s ovaries and pleopods (swimmerettes) to assess reproductive development. Across the four LFAs, the team processed 1,207 ovaries and 1,508 pleopods. The work contributes to better understanding of how maturity varies regionally and over time, key information for maintaining healthy lobster populations.

This project emerged from discussions at the first Canadian Lobster Research Network meeting in 2024, where partners identified maturity as a key knowledge gap. In recent decades, harvesters have been seeing more smaller egg-bearing females. This may be linked to climate change, with temperature playing a major role in declines in SOM50 in the US. There are still large gaps in SOM50 data across the species’ range, with many areas lacking estimates. Understanding SOM50 and the changes it’s undergoing is essential for assessing lobster populations and guiding effective management, making ongoing research critical.