How does aquaculture compare with commercial fisheries in Ontario?
In 2014, commercial fisheries caught over 11 thousand tonnes of fish, a decline of more than a half since 1990. Aquaculture has remained flat for the last 15 years with an average of 4 thousand tonnes.3 Industry sees opportunity in net pen (cage) aquaculture and cites Iran as a jurisdiction to model for growth. In Iran, the industry has multiplied rapidly with government support, from 5 thousand tonnes in 1978 to about 375,000 metric tonnes of fish in 2014. However, the Iranian example includes several species including Asian carp, shrimp, saltwater fish, as well as coldwater trout. With limited freshwater and different species, Iranian industry farming is also comprised of several different farming methods, including the use of raceways, ponds, and land-based systems. In addition, those numbers include the fish fry the industry raises to help re-stock depleted fish populations to aid commercial fishing.4 As growth is considered, some important differences arise around diversity of species, location, and methods.
Why is it important for the Georgian Bay Community to be engaged?
Regulatory lull provides opportunity to better understand impactsRight now, there is a critical opportunity for Georgian Bay Forever to work with partners to provide scientific research into potential interactions to further inform debate around sustainable aquaculture. We will be sharing this information with stakeholders and authorities. It is complex, and there is a range of stances on what “sustainable” means with respect to net pen aquaculture that are ever evolving as stakeholders lobby each other and more research becomes public. Some stances include: banning future net pen aquaculture growth (the Great Lakes Fishery Commission, US advisors)5, another looks to improving regulations around site selection based on areas where more phosphorus inputs may not be problematic. It should be noted that Ontario is alone among Great Lakes jurisdictions in its allowance of open net pen aquaculture.The DFO is currently investigating the possibility of creating an Aquaculture Act. The Canadian Aquaculture Industry Alliance observes that “The proposed Aquaculture Act represents a step forward in modernizing how Canada views, regulates, and enables growth of our industry. Rather than being regulated under a 150 year old Fisheries Act, the Aquaculture Act would recognize our industry as a farming activity – consistent with the approach of other leading jurisdictions around the world.”6
What has GBF found in past research on cage aquaculture impacts?
- 1. Synthesizing past net pen aquaculture research on freshwater impacts.
2. Using stable isotopes and fatty acids to determine if native fish were consuming aquaculture feed, with the potential to use DNA barcoding in future research.
3. Developing research questions and methodologies to fill in the gaps and address concerns to be able to implement a more sustainable policy.
TakeawaysUnder commission by GBF, the University of Guelph (U of G) looked at 56 research reference points to produce a summary, Freshwater Aquaculture: A review of the Environmental Implications (09/26/2017). The full report can be found at this link , but it came to the conclusion that “If the net-pen aquaculture industry is to continue and expand in The Great Lakes, there needs to be improvement to policy regarding the establishment of cage aquaculture operation, and a better understanding of how freshwater cage culture affects lake ecosystems is required to meet this objective.”1 The main issues generating environmental concerns fall under these categories:
Waste production and uptakeWHAT IS IN THE EXCESS FEED THAT FALLS THROUGH CAGES, AND MOST IMPORTANTLY BY VOLUME, WHAT IS IN THE FAECAL MATTER? HOW ARE THESE ABSORBED BY SPECIES IN THE SURROUNDING WATERS? IS WATER QUALITY IMPACTED? The main concern is nutrient subsidies of primarily phosphorus (in solid or liquid form) augmenting those found in the natural environment. This concern has been partially attenuated by industry through good husbandry practices, but certainly not entirely eliminated.The 2 broader fallout concerns are as follows: CONCERN 1: Excess phosphorus in the aquatic environment can result in “significant algal blooms and eutrophication”1. Eutrophication starves lakes of oxygen and leads to death of animals in that water body.The good news is that phosphorus loading in aquaculture has been steadily reduced over the years due to changes in the make-up of the feed, and site selection. The feed is a huge expense for the industry, so reducing waste also reduces feed costs. Sites that have more dynamic water circulation and more depth are better than stagnant, enclosed bays. “In general, the reviewed literature supports the view that modern cage farms with good husbandry that are located in well-flushed, deep basins do not show significant, long-term effects on water column nutrient concentrations.”1 CONCERN 2: Human derived subsidies of nutrients (extra feed and fish waste) can be consumed by native species, altering the food web and potentially impacting species health. “This organic material can act as a food source for invertebrate and fish species, and studies have shown that natural fish populations surrounding cage culture operations exhibit a shift in diet towards that of the released cage culture feed and waste (Fernandez-Jover et al., 2007a; Fernandez-Jover et al., 2011).”1 U of G further notes there have been some studies in small experimental lakes that have shown “increased abundances of benthic organisms, increased growth, reproduction and densities of invertebrates and small fish.”1 However, these cannot be directly applied to more dynamic and larger lakes that are more commonly chosen for aquaculture.
SedimentationDO SOLID WASTES FROM NET PEN AQUACULTURE ACCUMULATE TO AN EXTENT THAT RISKS MORE RELEASE OF PHOSPHORUS INTO THE WATER COLUMN AND IS THERE A SIGNIFICANT REDUCTION OF OXYGEN LEVELS AS THE WASTE DEGRADES?This is an unresolved issue. The concern with excessive phosphorus (P) is that it is the limiting nutrient in freshwater lakes and can lead to toxic and non-toxic cyanobacteria blooms resulting from eutrophication.However, there is a wide range of potential P release from sediments depending on conditions, including one reference noting a 7% to 64% spread.1 The U of G summary noted that “the factors affecting the rate and total proportion of P that is recycled from sediment into the water column have not been well studied in Ontario or with current feed formulations and practices. Since P is the nutrient limiting primary production in lakes, and that the solid waste portion of P is the largest component of P lost to the environment, this knowledge gap significantly hinders our ability to predict the effects of aquaculture activities on lake productivity (Temporetti and Pedrozo, 2000).”1Providing some needed insight into the complexities around release of phosphorus from sediment is a 2014 study by L.A. Molot et al., entitled “A novel model for cyanobacteria bloom formation: the critical role of anoxia and ferrous iron”7 published in Freshwater Biology that was partially funded by GBF.MOLOT CHALLENGES THE PRIMACY OF PHOSPHORUS (P) AS AN EXCLUSIVE FOCUS TO MANAGING RISK OF CYANOBACTERIA FORMATION.The major argument is that ferrous iron (Fe2+) regulates the ability of cyanobacteria to compete with its eukaryotic [non-toxic algae] competitors due to its increased iron requirements to support photosynthesis among other important environmental considerations. Therefore, cyanobacteria dominance emerges under more specific lake circumstances than previously widely considered. For example, it provides rationale that deep lakes are less susceptible to cyanobacteria bloom. The anoxic zone (low oxygen) is so deep that it falls below the mixing zone where anoxic sediments, Fe2+ and the euphotic zone (where photosynthesis occurs) could interact with cyanobacteria. Inshore regions or shallower lakes could be more prone. Furthermore, the report challenges where anoxia can develop, noting that it is not limited to eutrophic systems.In short, GBF believes the Molot paper highlights the need to not look in isolation at P sediment build-up from aquaculture sites, but examine other environmental circumstances and potential management solutions that effect cyanobacteria formulation. (Read the report at this link.)In the meantime, there have been some mitigation measures and potential solutions offered that could decrease the accumulation of sediment that contains P. These include: sediment regulations, fallowing, and more efficient feed formulations and technological cage innovations that can capture some of the waste.
Ecological and genetic interactions that may occur between escapees and indigenous speciesRecent news reports on our ocean shores show that this is a risk. A most recent example is an incident last summer involving a fish farm owned by Cooke Aquaculture Pacific. Pens collapsed under high winds letting up to 263,000 Atlantic salmon escape into the Pacific where they became invasive species with potential consequences for native salmon.9The same Globe and Mail article notes escapes that have happened on the East Coast resulted in some hybrids that are less capable of survival. According to Globe and Mail source Neville Crabbe of Canada’s Atlantic Salmon Federation, “Wherever the open net pen industry is established on the east coast of North America, the wild salmon populations have plummeted.” While not an exhaustive list of all the factors that could impact native ecosystems and water quality, the above is a summary of issues that were found by the GBF/UofG background research project.As noted earlier, for more information, please check the full report.
2017 GBF commissioned research produces proof of food web interference.
New research will fill gaps and lead to more informed sustainable policy.
The big questions GBF must tackle next
- What are the impacts to local ecosystem structure and function, particularly local native fish populations?
- How do the human derived subsidies of excess feed and faecal matter impact the food web in Georgian Bay aquaculture locations?
- How do the effects of aquaculture vary among sites that differ in placement (e.g. depth and exposure) and management practices (e.g. feeding regimes)?