Bottom Trawling

Bottom Trawling. One of the most common ways to catch fish is by dragging nets along the seafloor. This causes changes in the plants and animals that live there. When the same areas are trawled frequently, the community on the seafloor can be drastically changed. Long-lived species such as corals and sponges are severely affected. Approximately 15 percent of the continental shelf of the world is being trawled each year, with great variability between regions. Where trawl frequency is low, the seafloor communities are only lightly impacted. Most trawling is concentrated in the same, highly productive areas, year in and year out.

Seafood Certification and Non-governmental Organizations

Seafood Certification and Non-governmental Organizations. In the last 20 years, many non-governmental organizations (NGOs) have become involved in providing advice on what seafood to eat, or in certifying different seafood products as well-managed or sustainable. The same NGOs have also become quite involved in the politics of fisheries management. The Marine Stewardship Council provides the most widely recognized certification of seafood sustainability and is increasingly demanded by major retailers in some countries. NGOs involved in marine conservation have become a roughly $500-million-per-year business, funded by foundations and private donors, and with a business model that compels them to raise concerns about fisheries sustainability to maintain cash flow.

Who Gets to Fish?

Who Gets to Fish. Garrett Hardin’s “The Tragedy of the Commons” is the most important concept in managing fisheries. Simplified, it states that when a resource such as a fishery is held in common, everyone will act in their own best interest and, as long as it is profitable, will fish hard enough to deplete the resource. In Western countries, fisheries management has successively restricted who is allowed to fish. The declaration of 200-mile fishing zones around coastal countries closed coastal waters to foreign fleets. Efforts to limit access began by restricting the number of vessels and then progressed to limiting catch or days at sea. Various forms of allocation to fishing vessels, individuals, or groups have in effect privatized the fishery. While leading to generally increased economic efficiency and smaller fishing fleets, the result has often been a concentration of ownership in few hands that are often large corporations.

The Future of Fisheries

The Future of Fisheries. The much-ballyhooed imminent collapse of the world’s fish stocks is simply not borne out by the available data. In much of the world, fish stocks are increasing. We foresee continued fish production wherever there is effective fisheries management, but an uncertain future where there is none, and it is there that establishing effective fisheries management is the most pressing issue. Individual countries and their management agencies will increasingly be challenged to decide between economic efficiency and maintaining traditional fishing communities and practices. As long as the management systems stay in place and the marine ecosystems remain productive, the fish they produce can be sustainably harvested and contribute to food security.

Enhancement and Aquaculture

Enhancement and Aquaculture. Fish stock enhancement involves growing small fish in a hatchery and releasing them in the wild to augment natural fish production. It is widely practiced for Pacific salmon and hundreds of other marine species, especially in China. Aquaculture is the raising of fish from egg to adult in ponds, net pens, or other controlled conditions, and its harvest now exceeds capture fisheries. Aquaculture impacts wild fish production through disease transmission, genetic impacts from escaped fish, and introduction of exotic species. As fish stocks decline and the political, social, and economic pains of ever-reducing harvests increases, the idea of hatcheries becomes irresistible. Why regulate fisheries when you can produce more fish in a hatchery?

Ecosystem-Based Management and Marine Protected Areas

Ecosystem-Based Management and Marine Protected Areas. Ecosystem-based management (EBM) can be seen as a comprehensive strategy that includes the concern about the sustainable yield of fish alongside the ecosystem impacts of fishing and the impacts of fisheries management on human communities. While preventing overfishing goes a long way toward reaching its objective, protecting sensitive habitats from damaging fishing gear and reducing or eliminating bycatch of birds, mammals, and turtles must be given their due importance. Consideration should also be given to the trophic knock-on effects of fishing for one species that may cause other species less or more abundant. Marine protected areas are still considered the magic key to EBM, but their impact on total fish abundance has rarely been evaluated.

The Forage Fish Rollercoaster

The Forage Fish Rollercoaster. Forage fish are the small fishes such as sardines, anchovy, mackerel, and herring that are among the most abundant fish in the sea and form the base of the fish food chain. They are often the dominant food for predatory fish, marine mammals, and marine birds. Forage fish are used both for direct human consumption and for the production of fishmeal and fish oil used as livestock and aquaculture feed. Many species of forage fish have shown vast cyclical variation in abundance long before industrial fishing began, and this complicates understanding how fishing affects their abundance. A recent concern is the effect that fishing of forage fish has on the abundance of their predators.

Mixed-Species Fishing and Bycatch

Mixed-Species Fisheries and Bycatch. Most forms of fishing catch a range of species, both desired catch and nontarget species including birds, mammals, and turtles. Reducing or avoiding bycatch can be achieved by modifying fishing gear and how it is deployed, as well as where fishing is allowed. With appropriate incentives, fishing fleets have been able to greatly reduce bycatch. Any mixed catch of target species poses special problems because different species have different life histories that require different harvest rates. Choosing place and time to fish, as well as gear modifications, can mitigate, but, in general, there will be a trade-off between overexploiting low-productivity species and underexploiting productive species.

Freshwater Fisheries

Freshwater Fisheries. Be it conservation concerns associated with overfishing, food production of large fisheries, or the economic potential of a nation’s fisheries, marine fisheries dominate the political and scientific discussion. However, freshwater fisheries are the most important for food security and employment in areas around tropical river and lake systems. It is estimated that the potential yield from freshwater fisheries is comparable to marine fisheries, but data on catch are poor. What we do know is that in many tropical countries, freshwater fisheries are very important but, generally, they are poorly regulated and studied. Major threats to freshwater fisheries include dam construction, pollution, and introduction of exotic species.

Climate Change

Climate Change. The oceans are changing. There is no doubt that the oceans are rapidly getting warmer and more acidic, and this will have significant impacts on fish production. Warmer water causes species to migrate toward polar regions, and increasing acidification will make it more difficult for many species for form shells. It is challenging to make detailed predictions in the face of such unprecedented changes, but the important questions are how, whether, and which species will be able to adapt. The key to management in the face of climate change is the adaptability of our fisheries and fisheries management systems.