Overall projected changes in offshore lobster habitat for the region, as a whole, appear to be positive.
However, changes in resource management need to be considered to promote the long-term sustainability of the fishery in Nova Scotia, according to the findings of a new study published this fall in Frontiers in Marine Science.
The study was a collaboration between researchers at the Department of Fisheries and Oceans’ Bedford Institute of Oceanography (BIO) in Halifax and the National Oceanic and Atmospheric Administration’s (NOAA) Northeast Fisheries Science Center in the U.S.
The report, entitled Climate Change Vulnerability of American Lobster Fishing Communities in Atlantic Canada, frames a climate change impact assessment using a geographical perspective based on the management units of the dominant fishery, say the authors.
The study considered numerous elements:
- Information on the economic dependence on the fishery
- Population size
- Diversity of the fishery revenue
- Status of harbour infrastructure
- Total replacement cost of each harbour
- Increased relative sea level and flooding
- The vulnerability of offshore lobster to ocean warming
- Changes in zooplankton composition
- Anticipatory changes in fishery productivity across management borders
Researchers generated two climate change vulnerability indices — one for coastal communities and one for lobster in Nova Scotia. Two ocean models, a regional ocean model with high resolution in the Scotian Shelf and Gulf of Maine region and a global climate model, provided projections of ocean bottom temperatures over multiple decades.
The coastal infrastructure vulnerability index puts a numerical value on each lobster management area to indicate relative vulnerability to the effects of climate change. Factors included economic dependence on the fishery, community population size, diversity of the fishery revenue, status of harbour infrastructure, total replacement cost of each harbour, increased relative sea level and flooding, impacts of wind and wave, climate and sea ice.
The vulnerability index also puts a numerical value on the vulnerability of offshore lobster habitat to ocean warming and changes in zooplankton, a primary prey, as well as anticipated changes in fishery productivity across management borders.
The lobster vulnerability index formula consisted of two sub-indices: exposure and stock status. Exposure consisted of the per cent change in suitable habitat for American lobster in response to projected changes in bottom temperature from the two ocean climate model projections and stock status was comprised of four component variables: potential suitable habitat, occupancy, abundance status and early life stage food availability.
The study states that “when lobster vulnerability is combined with climate change-related vulnerabilities of coastal fishing communities, it is evident that adaptation planning is needed for long-term sustainability. This impact assessment provides both a framework and information for further in-depth analyses by climate change adaptation planners and fishery managers.”
Study authors suggest the new assessment tool could prepare a region for changes in potential catch through adjustments in licensing and quotas and by adapting to a decrease in productivity by encouraging and assisting fishermen to diversify their targeted species, where they fish, or to seek non-fisheries-related income. It could also support planning for projected increases in catch through investing in upgrades to coastal community infrastructure.
DFO spokesperson Debra Buott-Matheson said the study has contributed to the department’s overall understanding of the current and potential impacts of climate change on the lobster fishery.
“Fisheries and Oceans Canada is looking at how we consider the impacts of climate change in our fisheries management decisions.”
According to the study, current lobster habitat suitability is higher and more widespread in the western waters of Nova Scotia, including the Bay of Fundy and Browns Bank, and is moderate throughout the Gulf of Maine and on the outer part of the Scotian Shelf.
“By mid-century, both future climate model scenarios project an increase and expansion of habitat suitability” in most lobster fishing areas (LFAs), says the report.
In the Bay of Fundy (LFA 35) “there is a decrease in suitability… suggesting that these waters will begin to warm beyond optimal temperatures by mid-century.”
The study concludes that the results “highlight the importance of coastal adaptation planning and flexible fisheries management that is capable of making adjustments in a dynamic environment impacted by climate change.