The United Nations recognizes climate change as one of the greatest challenges to global food security this century. Both terrestrial and aquatic environments are changing as a result of increased greenhouse gas (GHG) emissions such as carbon dioxide, methane and nitrous oxides which result from the burning of fossil fuels and food production.
The agriculture and fishing industries are contributors to GHG emissions around the world, however, the good news is that the impact is much less than that of other industries.
Atmospheric carbon dioxide equivalents have increased fourfold in the past century compared to the previous 800,000 years. The average temperature on earth has increased by about 1.5 degrees in the past few decades and will increase by 6 degrees by the end of the century.
Although the planet has seen higher average temperatures in the past, the rate of change is much higher than previously observed.
These global changes in atmospheric temperature are causing shifts in climatic conditions. A few observations will give you an idea of the scale of the problem:
- Melting of polar ice caps — the polar ice cap is melting at an unprecedented rate and sea level has risen by several centimeters. As a result, salt intrusions, erosion and storm surges are ruining farmland in coastal areas.
- Weather bombs are more violent — while storm frequency has not changed much, the intensity of storms has increased. This includes higher winds and more precipitation in major events around the planet. Recall, we have had three hurricanes in Atlantic Canada in the past decade with significant damage to coastal areas.
- Temperatures are increasing — in northern climates, warmer winters and summers are welcomed, however there are consequences. Most organisms do not adapt rapidly to these fast changing temperature conditions, including fisheries or aquaculture species. This means they may be under stress for a good portion of their life cycle and more likely to be affected by pest, parasites or pathogens. In tropical zones, dry season temperatures often exceed 40 degrees Celsius for weeks on end and this is affecting their ability to produce food on land and in aquatic environments.
- Changing ocean currents are driving a lot of the climate changes seen today on land and at sea. These affect not only temperatures, precipitation and wind patterns, but major shifts in nutrient dynamics in coastal areas. For instance, the reduced ice cover in eastern North America during the winter has shifted the timing of plankton blooms, resulting in different recruitment and growth patterns for organisms such as mussels and lobsters.
- Dead zones and ocean acidification — large “dead” zones are increasing in the ocean. These are areas where little or no oxygen is found for portions of the year. These can result in disruption of fish movement patterns, changes in productivity, and even major fish kills. Secondly, we are seeing an increase in the acid content of marine coastal areas, all due to GHG. Even very slight decreases in pH, for example, cause stress in many marine organisms, resulting in poor reproduction (for example, wild oysters on the west coast).
Impacts on Fisheries and Aquaculture from Climate Change
The following is a short list of impacts we are already seeing around the globe:
- Farming and harvesting equipment damage or losses due to increased storm surges, intensity and ocean currents.
- Variable product quality, from multiple spawnings, reduced yields, and shorter shelf life in some farmed and harvested products.
- Increased prevalence of pests, parasites and diseases. Not only because they have been introduced accidentally but because in some cases their range has been extended into new territory due to climate change. The farm and harvest animals are not able to withstand the rate of the changing environments. We have seen increased mortality in rivers and oceans in some wild fishery species due to climate related events.
- Harvesting and market access have been affected by impacts associated with climate change. For instance, the lack of winter ice makes it difficult to harvest mussels in eastern North America in the winter months. As well, increased storm intensity means transportation of market product from Newfoundland and Labrador or Prince Edward Island via the bridge are compromised on occasion. Access to fishing grounds is also impaired at times due to severe weather.
- Changes in reproductive patterns in a number of species as they attempt to adapt to changing climatic conditions. These changes mean there is greater variability in recruitment in some cases and predicting stock status is increasingly more difficult. This is having an impact on wild seed collection in aquaculture and harvesting quota estimates for fisheries.
In short, changing aquatic environments are impacting aquaculture and fisheries globally, and the United Nations’ FAO predicts greater impacts on wild stocks of fish and shellfish from climate change.
Adapting to Climate Change
The good news is that aquaculture and fisheries are two of the “greenest” types of animal food production, in terms of carbon outputs and environmental impacts. They contribute relatively little to GHG emissions. In fact, throughout Asia and Africa, small scale integrated farming of fish and agriculture crops is actually viewed as an important adaptation to climate change in that it provides an additional measure of food security in a changing environment, in the event of a catastrophic loss of one crop or another.
For northern climates, including Canada, farmers and fish harvesters need to be aware how their environment is changing and what possible mitigation steps are available to them. For example, increasing the number of farm sites and reducing densities of animals could be one strategy to reduce stress and susceptibility to opportunistic parasites or pathogens.
Development of vaccines for emerging diseases and increased biosecurity will be important for reducing losses due to fish health concerns. For fisheries, improved vessel design, capacity, and more sustainable fishing practices will only help to mitigate the effects of climate change.