Fish Resources
Wild populations of fish have long been exploited as food. In recent decades, there have been enormous increases of the rate of harvesting of wild fish, and also in the cultivation of certain species in semi-domestication, a practice known as aquaculture. Like crop plants, livestock, and forests, populations of fish can be harvested in a sustainable manner, which would allow the yields to be maintained. However, fish stocks can also be over-harvested to the degree that their regeneration is impaired. When this happens, productivity declines and the bio-resource can disastrously collapse. Regrettably, the recent history of many of the world’s major fisheries provides abundant examples of over-exploitation causing rapid declines in resources.
The global harvest of fish, crustaceans, and shellfish in 2012 was about 91-million tonnes. This included 66-million tonnes of marine fish (representing a 4% decrease over 1993), 10 x 106 t of freshwater fish (a 91% increase), 1.7 x 106 t of diadromous fish (these are mostly salmon that migrate between salt and fresh water; +6%), and 44 x 106 t of fish grown in aquaculture (294% increase) (Table 14.11).
Table 14.11. Fish Catches and Aquaculture in Selected Countries. Data are in 106 t/y in 2012, with percentage increase since 1993 given in brackets. Countries are listed in order of decreasing catches of marine fish (data include diadromous fishes). Source: Data from FAO (2014).
Image 14.3. Bottom-dragging is a technology used to harvest fish or scallops by drawing an open net along the sea floor, which in some respects is the marine equivalent of clear-cutting a forest. This boat is used to drag for scallops off southwestern Nova Scotia. Source: B. Freedman.
p class=”comments-section”>Canada is a major fishing nation, with an annual harvest of 803-thousand tonnes of marine fish in 2013, with a value of $2.1 billion (Table 14.14). There was also a substantial harvest of freshwater fish, equivalent to 29 x 103 t and a value of $67 million. Aquaculture is also becoming increasingly important. The total harvest of fish in 2013 was 174-thousand tonnes, with a value of $834 million. Total exports of fish products had a value of $4.15-billion. The exports were partly offset by fish imports of $2.74-billion, for a net trade balance of $1.41-billion in this economic sector.
The most important marine species harvested are summarized in Table 14.12. Note that these data are for Canadian landings only. Some foreign nations also fish waters within Canada’s 320 km management jurisdiction, but their landings are not included in the table.
Table 14.12. Landings of Selected Fishes in Canada. Catch biomass is in 103 t/y, and economic value is in millions of dollars. Data are for 2012. Source: Data from Fisheries and Oceans Canada (2014a).
In 1992, the total catch of cod in Atlantic Canada was 239-thousand tonnes, of which 80% was landed by Canadian vessels and 20% by the foreign fleet working within the 320-km ma