(Disponible en français : Changements climatiques : impacts sur les pêches maritimes et l’aquaculture canadiennes)
Climate change is increasingly challenging the sustainability of Canada’s $3.5-billion marine fisheries and aquaculture, two industries of particular economic and social importance to communities on all three coasts.
The challenges of dealing with climate change are complicated by uncertainties about its impact. This makes it even more difficult for managers and policy makers – on both domestic and international levels — to develop strategies taking into account the implications of a changing marine environment on fisheries and aquaculture.
Shifting ocean conditions
Canada borders three interconnected oceans. Greenhouse gases and climate change drive a number of changing ocean conditions, including:
- Warming sea water temperature, particularly near the surface;
- Increasing acidification;
- Declining dissolved oxygen content of sea water; and
- Decreasing sea ice cover.
The challenges posed by these changes depend on their intensity and the vulnerability of the regions affected. The Gulf of Alaska, Scotian Shelf and Hudson Bay ecosystems are, for example, some of the global marine hotspots, areas that are warming faster than 90% of the oceans (Figure 1). Parts of the Arctic Ocean, such as the Beaufort Sea, are especially vulnerable to acidification.
Sources: Map prepared by Library of Parliament, Ottawa, 2016, using data from A. J. Hobday and G. T. Pecl, “Identification of global marine hotspots: sentinels for change and vanguards for adaptation action,” Reviews in Fish Biology and Fisheries, Vol. 24, 2014, pp. 415–425; and Natural Earth, 1:50m Cultural Vectors. The following software was used: Esri, ArcGIS, version 10.3.1. Contains information licensed under Open Government Licence – Canada. The ocean basemap layer is the intellectual property of Esri and is used under licence; © 2015 Esri and its licensors.
Impact on marine organisms
Warmer water initially accelerates the growth rate of marine organisms, but rising temperatures have metabolic effects and increase susceptibility to disease. Thus, some species may shift to deeper waters or move northward in response to ocean warming.
Acidification threatens the ability of aquatic calcareous organisms to form shells and, therefore, the fish that depend on them. Eggs and larvae of fish may also be directly affected by increased acidification.
A shortage of dissolved oxygen (hypoxia) leads to reduced growth rates and reproductive success, as well as higher mortality. Hypoxia can also result in shifts in the distribution of fish, as species migrate in search of higher oxygen levels.
The decline in sea ice cover in the Arctic Ocean will likely disrupt ice algae, upon which many native fish species depend. However, reduced ice cover may also improve conditions for fish stocks, such as Greenland halibut, by increasing the productivity of their prey and providing more extensive habitat.
Given the complex nature of oceanic changes and the uncertainty about their interplay, the responses of marine organisms to effects of climate change are not well understood. The overall impact on fish stocks, therefore, remains uncertain.
Risks and opportunities for marine fisheries and aquaculture
Research to date suggests that drastic changes in fisheries, both in terms of volume and value, are unlikely to occur in any of Canada’s three oceans over the next 10 years. In the longer term, however, climate change will result in the harvesting of new species, and changes in fishing locations, times and methods of capture.
Overall, the volume of fisheries is expected to increase, but changes in the location and type of species will dictate the economic value of this sector.
- Atlantic aquatic basin
A population decline is likely in the southern range of shrimp, crab, Greenland halibut and Atlantic salmon. The productivity of species, such as lobster and mackerel, is expected to be enhanced, although they may shift northward.
It has also been suggested that ocean warming may be a contributing factor to the potential recovery of capelin and cod stocks off the coast of Newfoundland and Labrador. Acidification of the ocean, however, may reduce the productivity of crustaceans and mollusks including lobster, crab, shrimp and oyster.
- Pacific aquatic basin
The cod population is likely to decline. However, stocks of hake, sardine, halibut and herring are expected to remain relatively stable within the next 50 years, while their range may extend northward.
Fraser River’s salmon stocks are projected to decline, but stocks in northern rivers could benefit from improved ocean productivity. Scientists have also predicted significant declines in First Nations’ subsistence fish catches in southern waters by 2050.
- Arctic aquatic basin
As the extent of sea ice declines, areas that have been previously inaccessible may become open for fishing. However, under current environmental changes, there are declining trends in the harvest levels of some fish species, including herring and char, which subsistence fishers in several Inuit communities rely on.
The aquaculture industry is also expected to be affected by changes in ocean conditions. However, aquaculture has a greater scope for adaptation compared to marine capture fisheries. Aquaculture operations may be able to relocate and change species, as well as altering the timing of cultivation.
Adaptive management efforts by the federal government
Uncertainties about the impacts of climate change complicate population estimates and management decisions on harvest levels based on historical data. These uncertainties are compounded by the combination of cumulative climate risks and human impacts, such as marine pollution.
At the federal level, climate factors were taken into consideration in developing adaptive policies and action plans such as the 2005 Wild Pacific Salmon Policy, the 2007 Ecosystem Science Framework, and the 2010 National Aquaculture Strategic Action Plan Initiative.
In 2011, the federal government invested $16.5 million over five years to implement the Aquatic Climate Change Adaptation Services Program, which produced risk assessments for the Department of Fisheries and Oceans. In 2012, the Department acknowledged that “climate change will affect [its] ability to manage and protect the abundance, distribution, and quality of harvested fisheries and aquaculture stocks.”
In its March 2016 Budget, the federal government announced an investment of $197.1 million over five years to increase ocean and freshwater science, monitoring and research activities, including research into the health of fish stocks and sustainable aquaculture.
An issue of international governance
All nations share one global common ocean, the waters of which are interconnected. Accordingly, the health of the oceans constitutes an international governance issue.
In September 2015, 193 United Nations members, including Canada, unanimously adopted the 2030 Agenda for Sustainable Development. Goal 14 aims to conserve and sustainably use the oceans, seas and marine resources, and includes a target to “minimize and address the impacts of ocean acidification.”
In advance of the 21st Conference of the Parties to the United Nations Framework Convention on Climate Change (UNFCCC) in Paris in December 2015, Canada and 21 other countries also endorsed the Because the Ocean declaration. It calls for:
- A special report of the Intergovernmental Panel on Climate Change on the ocean;
- A United Nations Conference on Oceans and Seas in June 2017 to promote implementation of goal 14; and
- Development of an ocean action plan under the UNFCCC starting in 2016.
Campbell, I.D. et al., “Food Production,” Chapter 4 in Canada in a Changing Climate: Sector Perspectives on Impacts and Adaptation, F.J. Warren and D.S. Lemmen (Ed.), Government of Canada, Ottawa, 2014, pp. 99-134.
Fisheries and Oceans Canada, Short-Term Stock Prospects for Cod, Crab and Shrimp in the Newfoundland and Labrador Region (Divisions 2J3KL), Canadian Science Advisory Secretariat Science Response 2014/049, November 2014.
Lam, Vicky W.Y. et al., “Marine capture fisheries in the Arctic: winners or losers under climate change and ocean acidification? ” Fish and Fisheries, 2 December 2014.
Mercer Clarke C.S.L. et al., “The Coastal Challenge,” Chapter 3 in Canada’s Marine Coasts in a Changing Climate, D.S. Lemmen, F.J. Warren, T.S. James and C.S.L. Mercer Clarke (Ed.), Government of Canada, Ottawa, 2016, pp. 69-98.
Authors: Odette Madore and Thai Nguyen, Library of Parliament