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Five Knocks Against Farming Salmon Along NS Coast


Nova Scotia recently granted the Norwegian company Cermaq the right to explore a large area extending from St. Margarets Bay through to Green Bay on the South Shore, as well as St. Marys and Chedabucto bays, for potential sites for open-net pen salmon aquaculture.

The latter has been so controversial in B.C. waters that the federal government has pledged to work with the province to phase it out by 2025. Why should Nova Scotia increase its use of this environmentally damaging industry when our sister province is phasing it out?

I see several major reasons to oppose this expansion:

Potential harm to the lobster fishery. Lobsters are the major target of fishing in Nova Scotia. Lobster landings are good, prices are reasonable and the market is strong. Why worry? Two major factors jump out. Climate change is leading lobster abundance in the Gulf of Maine to decrease. Maine lobster fishers are concerned about their future. The centre of lobster abundance seems to be moving northeast as ocean temperatures rise. Our current riches may be fleeting as ocean temperatures continue to rise, leading our lobster abundance to fall. Given their financial and cultural importance, our lobster stocks need to be coddled, not stressed. So why worry about open-net pen culture? Raising salmon in the high densities of open-net pens requires a great deal of feed. Adding the excess nutrients to our fairly enclosed bays could stress lobster populations. Further, the pharmaceuticals used to treat sea lice harm lobsters, particularly at the larval phase.

Pollution of our waters. Estimates of fecal production by open-net pen salmon culture indicate that one mid-sized farm produces as much poop as 50,000 people. If such pollution occurred near beaches, it could lead to closures. The physical gear from aquaculture operations often gets dislodged, creating hazards in the water for boats and marine mammals, before washing ashore.

Escapes of Atlantic salmon. Remnant populations of wild Atlantic salmon are present in our areas. Considerable effort has gone into revitalizing river access to facilitate upstream migration by Atlantic salmon and gaspereau. In B.C., Atlantic salmon escapes cannot breed with native salmon, but they certainly could in Nova Scotia. Cultured salmon have been selected for fast growth and resistance to disease, whereas native salmon are adapted to local conditions and differ genetically from one watershed to the next. The potential of escapes from open-net pens is high and the genetic consequences for any remaining native Atlantic salmon populations would be major.

Finding areas in which open-net pens can be safely installed is a delicate balance between an adequate flushing rate and protection from storm damage. Bays and coves provide protection from storms, but the flushing rates may not be adequate to maintain water quality for the salmon or adjacent human populations.

Impact of increasing water temperatures on survival of salmon in open-net pens. The Atlantic coast of Nova Scotia has regular incursions of tropical waters, particularly during the hurricane season. We are all quite aware that the hurricane season is getting longer. Incursions of warmer water brought a protozoan disease that wreaked havoc with sea urchins, formerly a major component of our marine ecosystem. Sea urchins are now only found in deep, cold waters. Salmon maintained in open-net pens cannot escape to cold water when surface temperatures rise. As water temperature rises, their oxygen demand increases while oxygen availability in the water decreases. Locating open-net pens in protected areas (where temperatures are bound to rise) will surely lead to salmon mortalities. High temperatures may have caused the recent death of 2.6 million aquaculture salmon in Newfoundland. Logically, the increasing likelihood of high water temperatures in our bays, coves and offshore waters should make Cermaq decide against setting up here.

Helga Guderley, PhD, lives in Boutiliers Point.