Fisheries and the Environment
Commercial fisheries can do tremendous damage to the marine ecosystem if they are not managed properly. This became apparent in Newfoundland and Labrador during the 1990s, when decades of overfishing caused the northern cod stocks to collapse and resulted in a moratorium on the centuries-old industry. These were huge ecological and economic losses, which dictated an urgent need to change fisheries policy and practice in a way that would make the industry sustainable and protect marine biodiversity.
Overfishing is one way to disrupt ocean ecosystems. Allied causes are trawl nets and other fishing gear which destroy marine habitat and catch large quantities of juvenile and non-targeted fish species. In addition, processing plants and fishing vessels release greenhouse gasses and other pollutants into the environment.
Sustainable Fisheries and Overexploitation
Fish and shellfish populations are renewable, but they are not inexhaustible. If the industry takes more fish from the ocean than are being reproduced, then stocks will decrease and will collapse. A sustainable fishery harvests fish without depleting the population or jeopardizing the ecosystem, which includes marine life and habitat. Truly sustainable fisheries can protect the environment and provide human populations with jobs, food, and government revenues indefinitely.
However, overfishing is a persistent and potentially devastating problem in many of the world's fisheries. It was largely to blame for the commercial extinction of northern cod in the 1990s and has caused the depletion of many other fish stocks, including herring and tuna populations in the Atlantic and Pacific oceans. Some scientists estimate that the world's total biomass of cod, tuna, and other large predatory fish has dropped by 90 per cent since the industrialization of the fisheries in the 1950s.
Many factors have contributed to the overexploitation of fish stocks, but most important were the swift technological changes that took place after the Second World War. Increasingly efficient nets pulled in greater amounts of fish, while advances in sonar, radar, and other fish-finding aids allowed vessels easily to detect and track schools of fish. In 1954, the first factory freezer trawler appeared on the Grand Banks and hundreds more followed in the coming years. Factory freezer trawlers were the largest and most powerful vessels to ever fish on the banks and could remain at sea for months at a time. Fishing technology became so efficient that by the 1970s commercial catch rates in the offshore cod fishery remained high even as stocks dropped to dangerously low levels. This situation continued until the federal government imposed a cod fishery moratorium in 1992.
Inadequate understanding of fish populations and ocean ecosystems also contributed to overfishing. In the years leading up to the cod moratorium, fisheries scientists in Canada consistently overestimated the size of cod stocks. As a result, the federal government set quotas that were too high. The miscalculation resulted from the practice of basing stock size on the catch rates of offshore Canadian commercial trawlers. Modern trawlers can harvest large catches no matter what the size of the fish population, and ignoring this fact masked just how drastically the cod stocks had declined. Many inshore fishers reported cod were growing scarce in areas closer to land, but scientists in general chose to ignore their warnings in favour of offshore data.
Although overfishing is the major problem associated with commercial fisheries, it is not the only problem. Some types of fishing gear can cause severe damage by destroying habitat and trapping large quantities of juvenile and non-commercial fish. Offshore commercial fisheries use bottom trawls (also known as draggers) to harvest several marine species, primarily groundfish and shrimp. As the trawlers drag large nets and trawl doors across the seabed, they damage important seafloor habitat, destroy bottom-dwelling wildlife (such as corals and sponges), and cause sediment, organic matter, and other particles to become suspended in the water – all of which diminishes the overall health of the marine ecosystem.
Bottom trawling has been taking place on the Grand Banks for much of the 20th century, but intensified after the introduction of large factory freezer trawlers in the 1950s and 1960s. By 1980, approximately 390,000 square kilometers, or 38 per cent, of the Atlantic continental shelf was being dragged for fish. The trawl fishery targeted cod and other groundfish before 1992, but shifted attention to shrimp and turbot (also known as Greenland halibut) after the moratorium. By 2000, the area of the shelf being trawled had been cut almost in half to 20 per cent.
Nets may also haul in bycatch – species of fish that are accidentally trapped in gear targeting another species. Examples are codfish caught in the haddock fishery and snow crab in the turbot fishery. Harvesting large quantities of bycatch may place sensitive fish populations, such as cod, in jeopardy and interfere with the overall health of ocean ecosystems. Fishers can reduce bycatch by using gear that is designed to trap one species and let others go. Nets with large mesh, for example, can trap adult fish, but not juvenile fish and smaller species. A strategic placement of nets may also reduce bycatch. Turbot gillnets are much less likely to catch snow crab in deeper water than they are in depths less than 350 fathoms.
Fishing down the Food Web
After the cod stocks collapsed, the province's catch of shellfish steadily increased and today dominates the industry. Shrimp and crab are the two most valuable species harvested. This transition underscores the deep ecological changes that decades of overfishing have brought about. As cod and other groundfish declined in numbers, the species they preyed upon – including shrimp and crab – increased. The resulting shift in fishing effort, from top predators to smaller prey species, is known as 'fishing down the food web.' It is not an occurrence unique to the northern cod fishery and is usually the result of unsustainable fishing practices. As of 2011, the cod stocks have not yet recovered and it is unknown when or if they will.
There have been changes to the management of commercial fisheries in the wake of the moratorium. These include the introduction of fishing gear that trap fewer young fish and bycatch species; the posting of more independent observers on offshore fishing vessels; and the inclusion of more fishers, scientists, and other relevant personnel in fisheries management.
Despite these changes, concern persists that overfishing remains a problem and that the federal government is slow to implement the many changes that scientists and fishers recommend. After years of rising quotas in the snow crab fishery, for example, the stock showed signs of decline in 1999. This prompted a quota cut from 61,806 tonnes in 1999 to 51,098 tonnes in 2000, and again to 43,955 tonnes in 2005. Quotas remained below 48,000 tonnes until 2008, when they were raised to 54,320 tonnes.
It is critical that government and industry learn from past mistakes to sustainably manage present and future fisheries. The ocean has been a pillar of the Newfoundland and Labrador economy for centuries; it has also helped to shape our culture and heritage. Preserving its health should be of paramount importance.
Article by Jenny Higgins. ©2011, Newfoundland and Labrador Heritage Web Site.