Climate change is impacting global fisheries and societies that depend on them. Identifying climate adaptation measures requires understanding how environmental change and management policies interact in driving fishery productivity. Accompanying the recent exceptional warming of the northwest Atlantic Ocean and the removal of predatory fish, the American lobster has become the most valuable fishery resource in North America. Using a model that links ocean temperature, predator density, and fishing to population productivity, I showed that harvester-driven conservation efforts to protect large lobsters prepared the Gulf of Maine lobster fishery to capitalize on favourable ecosystem conditions, resulting in the record-breaking landings recently observed in the region. In contrast, in the warmer southern New England region, the absence of similar conservation efforts precipitated the warming-induced recruitment failure that led to the collapse of the fishery. These results demonstrate that sound, well adopted fishery conservation measures based on fundamental biological principles can help capitalize on gains and mitigate losses caused by global climate change (Le Bris et al. In press).
Development of geolocation model
High resolution fishery (semi) independent data recorded by electronic archival tags can provide unique insights into the annual migratory behaviour of marine fish. The first step in analyzing time series recorded by electronic tags is often to estimate the position of the tagged individual from recorded environmental variables (light, depth, temperature). This can be especially difficult for groundfish, because they are distributed too deep to obtain reliable light signals. A portion of my research is to develop new methodologies to geolocate groundfish from electronic tags. In my research, I have developed a geolocation model that has been used to reconstruct annual migration patterns of Atlantic cod (Le Bris et al. 2013a) and Atlantic halibut (Le Bris et al. 2017) in the Gulf of St. Lawrence. My lab is currently working on improving geolcoation methodologies for groundfish in Atlantic Canada and ensuring that these methodologies will be freely available to every researchers.
Migratory behaviour of Atlantic halibut
Atlantic halibut is currently the most valuable groundfish per unit of weight in Canada. However, very little is known about its biology and ecology, including its migratory behaviour. Using reconstructed tracks of fish tagged with pop-up satellite tags, we identified putative the locations of migratory corridors, spawning and feeding areas of Atlantic halibut in the Gulf of St. Lawrence (Le Bris et al. 2017 ; Murphy et al. 2017). New deployments of PSATs and future data analyses should soon shed more light on the migratory behaviour of Atlantic halibut.
Animal movement and fishery closure design:
Fish daily geolocation can also be used to improve the spatiotemporal design of fishery closures. For instance, post-analysis of geolocation estimates of Atlantic cod showed that the spring spawning closure in the Gulf of St. Lawrence would be more efficient if it was moved south and if the closure start and end dates were set earlier in the spring (Le Bris et al. 2013b).
Restoration of eelgrass meadows
Eelgrass is an ecologically significant species providing numerous ecosystem services. Eelgrass meadows have greatly receded in Placentia Bay, Newfoundland, possibly due to the invasion of European green crab. As part of a Coastal Restoration Fund project, we are mapping and restoring eelgrass meadows in Placentia Bay. We also aim to quantify the impact on restored eelgrass meadows on juvenile fish density in Placentia Bay.
Commercial fisheries, including the American lobster fishery, have been declining in Placentia Bay in the recent decades. In order to facilitate the rebuilding of these fisheries, we are deploying artificial reefs in 5 coastal sites of Placentia Bay to enhance lobster and fish habitats. We are using the reef design from the reef ball foundation, which has been used in hundreds of locations worldwide. We plan on monitoring the colonization of artificial reefs underwater high definition camera and scuba surveys.
American lobster size-at-maturity
Life-history traits respond to environmental changes and fishing pressure and these responses vary across scales. Using data from sea-sampling conducted with harvesters, we demonstrated that both increase in temperature and fishing reduced the size at maturity in the American lobster. These responses in size at maturity varied across spatiotemporal scales, potentially reflecting scale dependent processes such as phenotypic plasticity and local adaptation (Le Bris et al. 2016).
Fecundity and maternal effect
Variation in life-history traits affects population productivity. Understanding and quantifying causes of life-history can improves stock assessment models and predictions of stock status and contribute to establishing best management practices. Using a simple population dynamics model, we showed that high individual fecundity is more important for population resilience than maternal effects or batch spawning. The model also demonstrates that a slot fishery increases population resistance to overfishing but that a minimum size limit only benefits more the population recovery (Le Bris et al. 2015).
Main study species
Atlantic cod (Gadus morhua)
Atlantic halibut (Hippoglossus hippoglossus)
American lobster (Homarus americanus)
Centre for Fisheries Ecosystems Research
Marine and Fisheries Institute
Memorial University of Newfoundland
St. Johns, NL, A1C 5R3, CANADA