Effect of climate change on aquaculture

Researchers at the University of New Brunswick (UNB) and Fisheries and Oceans Canada (DFO) recently released a paper that explains some of the implications of climate change on aquaculture. Gregor Reid of UNB and Steven Leadbeater and Nathaniel J. Feindel at DFO’s St. Andrews Biological Station prepared the paper.

Reid, who is part of the Canadian Integrated Multi-Trophic Aquaculture Network, explains that the paper springs in part from the fifth report of the Intergovernmental Panel on Climate Change (IPCC) that was released last October. Over 600 authors from 32 countries contributed to that report.

         Much discussion about climate-change pertaining to aquaculture focuses on temperature and acidity. So it is that Reid turns first to temperature which he says is “perhaps intuitively the most influential effect for aquaculture.”

         “Increases in mean temperature within thermal tolerances will accelerate growth rates (for fish in aquaculture), assuming food availability,” he writes, but exceeding optimal temperature ranges will cause stress, impaired immune functionality and increased susceptibility to disease.

         “There are also temperature considerations for bioenergetic expenditures, such as diet digestibility and assimilation, respiration rate (oxygen consumption), enzymatic functionality, osmoregulation as well as reproductive cues and expenditures.”

         He also writes that temperature changes will alter fish-distribution ranges, and could well affect things like sea lice in farmed salmon, boosting the parasites’ growth and survival rates.

         Besides introducing new pathogens (but potentially reducing the incidence of others) Reid says temperature change also has the potential to shift predator patterns, which could affect aquaculture.

         “Another significant area of concern is ocean acidification,” he says. “Increased CO2 in conjunction with the resultant increase in acidity – decreased pH – is of particular concern for hatching success, larval survival and early-rearing of shellfish and some finfish.”

         The authors also note that severe weather events attributed to climate change are also of concern to the industry. Flooding or hurricanes for instance, could harm fish farms and hatcheries.

– Quentin Dodd