American lobster, Homarus americanus, framework and stock status in the southern Gulf of St. Lawrence : LFAs 23, 24, 25, 26A and 26B

Abstract

Preliminary Lobster landings of 39,313 t in 2021 in the southern Gulf of St. Lawrence (sGSL) are well above the Limit Reference Point (LRP, 6,899 t), and approximately 3 times the Upper Stock Reference (USR, 13,798 t) placing the stock within the defined healthy zone of the precautionary approach. Since the last assessment (2013), recent estimates of landings, catch per unit effort, and biomass and abundance indicators of commercial-sized Lobster have increased to time series high values. Based on a fishery-independent trawl survey conducted in the Northumberland Strait since 2001, Lobster abundance, biomass, and density have increased and their distribution has expanded into a wider range of depths. Productivity indicators - pre-recruit abundance, juvenile density, young-of-year density, and egg production - continue to increase or have stabilized at high levels. Continued increases in landings and high (> 50%) but largely stable exploitation rates suggest that the stock can likely sustain current levels of exploitation. Large decreases in the predator index, mainly due to decreases in groundfish abundance, since the early 2000’s, are indicative of a shift in the ecosystem. Trophic interactions involving Lobster may be changing, and attention should be focused on prey availability to Lobsters (particularly Rock Crab). The habitat index analysis showed increases in Lobster habitat in the sGSL, as a result of increases in bottom temperature. While temperature is an important factor in the distribution of Lobsters, additional factors could be considered in the future, including substrate and prey availability.