Prevailing notions of the ocean make it seem as if it is "too big to fail” since it takes up 70% of the surface of Earth and contains 321,003,271 cubic miles of water.1 Additionally, most of the oceans’ immense biodiversity has yet to be documented. The Census of Marine Life estimates that there could be between 178,000 to 10,000,000 different species living in ocean shoreline habitats due to the vast abundance of photosynthesizing microbes.2 However, like any ecosystem, the oceans are not immune to anthropogenic and environmental stressors such as overfishing, climate change, and pollution. There are many interconnected problems surrounding the way in which people currently treat the oceans. Extracting large amounts of fish for human consumption threatens the dynamic balance that currently exists and threatens scientists’ potential for making groundbreaking discoveries about what lies below.
In 2010, the United Nations predicted that over 80% of the world’s fish are reported as fully exploited or overexploited, and thus “require effective and precautionary management.”3 Overexploitation refers to the extraction of marine populations to unsustainable levels.4 Fishing techniques have become exponentially more efficient since the Industrial Revolution, focusing on getting the largest catches in the fewest trips. Today’s fishing fleets are so large that it would require two to three times Earth’s supply of fish to fill them.4 These harmful practices lead to three main types of overfishing:
- Growth overfishing: The removal of larger fish leaves behind only individuals that are too small to maximize the yield, or full amount of fish that could theoretically be obtained.5
- Recruitment overfishing: When adult fish are excessively taken out of the ecosystem, recruitment and stock productivity decreases.5
- Ecosystem overfishing: The targeting of a particular species leads to serious trophic cascades and ecological consequences.5
Unfortunately, the most popularly consumed fish species are subject to all three practices. Bluefin tuna, sturgeon, sea bass, and Atlantic salmon are examples of large, long-lived predatory species that only provide a few offspring each breeding cycle.5 For example, Bluefin tuna release ten million eggs each year, but only a small number survive to adulthood. Even then, these tuna do not reach reproductive maturity until eight to twelve years of age.6 When the largest fish are specifically targeted, many ecological consequences arise. Removing the largest fish of the largest species in an ecosystem significantly decreases the mean size for that species. As a result, only smaller fish are left to reproduce.7 This shift causes trophic level decline: as species at higher trophic levels are overfished, fishermen decide to catch the comparatively larger fish at lower trophic levels.7 This vicious cycle continues so that the average size of fish consumed decreases significantly. This phenomenon, known as “eating down the food chain,” puts many fish at risk, including herbivorous fish in coral reef ecosystems.7 To maintain a coral-dominated state, herbivorous fish consume macro-algae that otherwise would overgrow and suffocate corals. When coral-dominated reefs become overtaken by macro-algae, habitats for many other fish and organisms are severely reduced. Over 25% of the world’s fish species live exclusively within these three-dimensional coral communities, which themselves only take up 0.1% of the ocean floor.5 Not only are species being depleted at the very top of the food chain, smaller species that are endemic to specific ocean environments are also indirectly experiencing survival pressure.
These problems are further magnified by the fact that current fishing practices produce a large amount of by-catch, or the incidental capture of non-target species.5 The rustic image of a humble fisherman using a single hook at the end of a line no longer reflects reality for most commercial fishermen. Now, longlines are weighted at the bottom and can have as many as 3,000 hooks attached, probing deeper into the water column.8 A similar weighted system exists for large fishing nets, known as trawl nets, so that shellfish and other small or bottom-dwelling organisms can be collected in larger quantities. Bottom trawling, the practice of dragging a trawl net across the ocean floor, has contributed to 95% of the damage inflicted on deep water systems by destroying and smothering benthic communities.9 These practices are non-specific in nature, and thus collect anything and everything that attaches or gets caught. Fishing gear alone has threatened around 20% of shark species with extinction and leads to over 200,000 loggerhead sea turtles deaths annually.10 Sylvia Earle, a renowned ocean-conservationist, describes these unsustainable fishing practices as “using bulldozers to kill songbirds.”11
The United Nations now predicts that by 2050, the world will run out of commercially viable catches and oceans could turn fishless.3 Driving this problem is the fact that seafood consumption has increased over the past 30 years.12 Many coastal communities and developing countries rely on fishing as their main source of income and protein, with approximately 2.9 million people relying on fish for over 20% of their animal protein intake. One of the largest importers, the United States, imports 91% (by value) from other countries with lower production costs.13 The cheap labor comes from subsistence fishermen, who meet this increased demand by opting for unsustainable practices. Consequently, a “poverty cycle” emerges, where short-term survival takes precedence over sustainability and conservation efforts, further exacerbating ecological and economic damages.14
Recognizing that environmental considerations alone could put many developing countries at risk, policymakers have adopted a community-based approach in the planning, construction, implementation, and management of preservation policies.15 This ecosystem approach to fisheries, strives to ensure that the capability of aquatic ecosystems to provide the necessary resources for human life is maintained for present and future generations.16
The establishment of Marine Protected Areas, or MPAs, is another effective technique similar to the National Park Service’s preservation programs. Although MPAs have a wide range of management plans and enforcement, all strive to limit or restrict human activity so that natural populations can be restored.5 Allowing an environment to restore its fish populations without any human mitigation can take a long time, and the most effective MPAs extend across large tracts of area that can more fully encompass fish populations and migratory species.5 Because these areas often overlap with highly profitable fishing zones, MPAs are regularly met with backlash from coastal communities and later can be hard to enforce.17
These international efforts to reduce the amount of seafood extracted from ocean environments are generally invisible in a grocery store, so it is easy for consumers to engage passively with the food they see. However, recognizing the production, labor, and ecosystem that goes into fish and fish products (and all foods) is critical for maintaining the livelihood of the world’s natural environments. The ocean may seem vast, but there is not an infinite supply of resources that can meet current demands.
- National Oceanic and Atmospheric Administration. http://oceanservice.noaa.gov/facts/oceanwater.html (accessed Oct. 31, 2015).
- Smithsonian Institute. http://ocean.si.edu/census-marine-life (accessed Nov. 1, 2015).
- Resumed Review Conference on the Agreement Relating to the Conservation and Management of Straddling Fish Stocks and Highly Migratory Fish Stocks; United Nations: New York, 2010.
- Marine Biodiversity and Ecosystem Functioning. http://www.marbef.org/wiki/over_exploitation (accessed Oct. 31, 2015).
- Sheppard, C.; David,S.; Pilling, G. The Biology of Coral Reefs,1; Oxford University Press: 2009.
- World Wildlife Foundation http://wwf.panda.org/what_we_do/endangered_species/tuna/atlantic_bluefin_tuna/ (accessed Nov. 1, 2015).
- Pauly, D., et al. Science. 1998, 279, 860-863.
- Food and Agriculture Organization. http://www.fao.org/fishery/fishtech/1010/en (accessed Feb. 25, 2016).
- The Impacts of Fishing on Vulnerable Marine Ecosystems; General Assembly of the United Nations: Oceans and the Law of the Sea Division, 2006.
- Monterey Bay Aquarium. http://www.seafoodwatch.org/ocean-issues/wild-seafood/bycatch. (accessed Oct. 31, 2015).
- Saeks, Diane Dorrans. US oceanographer Dr. Sylvia Earle. Financial Times, Aug. 9, 2013.
- The State of World Fisheries and Aquaculture; Food and Agriculture Organization; United Nations: Rome 2014.
- Gross, T. ‘The Great Fish Swap’: How America Is Downgrading Its Seafood Supply. National Public Radio, Jul. 1, 2014.
- Cinner, J. et al. Current Biology. 2009. 19.3, 206-212.
- Agardy, T. M. ; Information Needs for Marine Protected Areas: Scientific and Societal; 66.3; Bulletin of Marine Science, 2000; 875-878.
- Food and Agriculture Organization. http://www.fao.org/fishery/topic/13261/en (accessed Nov. 1, 2015).
- Agardy, T.M.; Advances in Marine Conservation: The Role of Marine Protected Areas; 9.7; Trends in Ecology and Evolution, 1994; 267-270.