Figure 1. A comparison of the Aral Sea in 1989 (left) and 2014 (right). Credit: This work is in the Public Domain, CC0
The Aral Sea is a lake located east of the Caspian Sea between Uzbekistan and Kazakhstan in central Asia. This area is part of the Turkestan desert, which is the fourth largest desert in the world; it is produced from a rain shadow effect by Afghanistan’s high mountains to the south. Due to the arid and seasonally hot climate there is extensive evaporation and limited surface waters in general. Summer temperatures can reach 60οC (140οF)! The water supply to the Aral Sea is mainly from two rivers, the Amu Darya and Syr Darya, which carry snow melt from mountainous areas. In the early 1960s, the then-Soviet Union diverted the Amu Darya and Syr Darya Rivers for irrigation of one of the driest parts of Asia to produce rice, melons, cereals, and especially cotton. The Soviets wanted cotton or white gold to become a major export. They were successful, and, today Uzbekistan is one of the world’s largest exporters of cotton. Unfortunately, this action essentially eliminated any river inflow to the Aral Sea and caused it to disappear almost completely.
Figure 2. Map of Aral Sea Area Map shows lake size in 1960 and political boundaries of 2011. Countries in yellow are at least partially in Aral Sea drainage basin. Source: Wikimedia Commons
In 1960, Aral Sea was the fourth largest inland water body; only the Caspian Sea, Lake Superior, and Lake Victoria were larger. Since then, it has progressively shrunk due to evaporation and lack of recharge by rivers. Before 1965, the Aral Sea received 2060 km3 of fresh water per year from rivers and by the early 1980s it received none. By 2007, the Aral Sea shrank to about 10% of its original size and its salinity increased from about 1% dissolved salt to about 10% dissolved salt, which is 3 times more saline than seawater. These changes caused an enormous environmental impact. A once thriving fishing industry is dead as are the 24 species of fish that used to live there; the fish could not adapt to the more saline waters. The current shoreline is tens of kilometers from former fishing towns and commercial ports. Large shing boats lie in the dried up lakebed of dust and salt. A frustrating part of the river diversion project is that many of the irrigation canals were poorly built, allowing abundant water to leak or evaporate. An increasing number of dust storms blow salt, pesticides, and herbicides into nearby towns causing a variety of respiratory illnesses including tuberculosis.
Figure 3. This abandoned ship lies in a dried up lake bed that was the Aral Sea near Aral, Kazakhstan Source: Staecker at Wikimedia Commons
The wetlands of the two river deltas and their associated ecosystems have disappeared. The regional climate is drier and has greater temperature extremes due to the absence of moisture and moderating influence from the lake. In 2003, some lake restoration work began on the northern part of the Aral Sea and it provided some relief by raising water levels and reducing salinity somewhat. The southern part of the Aral Sea has seen no relief and remains nearly completely dry. The destruction of the Aral Sea is one of the planet’s biggest environmental disasters and it is caused entirely by humans. Lake Chad in Africa is another example of a massive lake that has nearly disappeared for the same reasons as the Aral Sea. Aral Sea and Lake Chad are the most extreme examples of large lakes destroyed by unsustainable diversions of river water. Other lakes that have shrunk significantly due to human diversions of water include the Dead Sea in the Middle East, Lake Manchar in Pakistan, and Owens Lake and Mono Lake, both in California.
Case Study: Marine Fisheries
Fisheries are classic common-pool resources. The details of the legal institutions that govern access to fisheries vary around the globe. However, the physical nature of marine fisheries makes them prone to overexploitation. Anyone with a boat and some gear can enter the ocean. One boat’s catch reduces the fish available to all the other boats and reduces the stock available to reproduce and sustain the stock available in the following year. Economic theory predicts that the market failure associated with open access to a fishery will yield socially excessive levels of entry into the fishery (too many boats) and annual catch (too many fish caught) and inefficiently low stocks of fish (Beddington, Agnew, & Clark, 2007).
Unfortunately, the state of fisheries around the globe seems to indicate that the predictions of that theory are being borne out. Bluefin tuna are in danger of extinction. Stocks of fish in once-abundant fisheries such as North Atlantic cod and Mediterranean swordfish have been depleted to commercial (and sometimes biological) exhaustion (Montaigne, 2007). Scientists have documented widespread collapse of fish stocks and associated loss of marine biodiversity from overfishing; this devastates the ability of coastal and open-ocean ecosystems to provide a wide range of ecosystem services such as food provisioning, water filtration, and detoxification (Worm et al., 2006). Scholars have documented isolated cases such as the “lobster gangs” of coastal Maine where communal informal management prevented overexploitation of the resource (Acheson, 1988), but such cases are the exception rather than the rule.
Early efforts to control overfishing used several kinds of regulations on quotas, fishing effort, and gear. For example, fishing boats are forbidden in some places from using conventional longlines because that gear yields high levels of bycatch and kills endangered leatherback turtles. Some forms of fishery management limit the number of fish that can be caught in an entire fishery. Under a total allowable catch (TAC) system, fishers can fish when and how they want, but once the quota for the fishery has been met, fishing must stop until the next season. Unfortunately, TAC policies do not solve the underlying problem that fishermen compete for the fish, and often yield perverse incentives and undesirable outcomes such as overcapitalization of the industry (Beddington, Agnew, & Clark, 2007) and races between fishing boat crews to catch fish before the quota is reached. In the well-known case of the Alaskan halibut fishery, the race became so extreme that the fishing season was reduced to a single 24-hour mad dash; given that fish are perishable, this temporal clumping of the catch is not a desirable outcome.
Resource economists developed the idea of a tradable permit scheme to help manage fisheries. Individual tradable quota (ITQ) schemes are cap-and-trade policies for fish, where total catch is limited but fishers in the fishery are given permits that guarantee them a right to a share of that catch. Players in the fishery can sell their quota shares to each other (helping the catch to flow voluntarily to the most efficient boats in the industry) and there is no incentive for captains to buy excessively large boats or fish too rapidly to beat the other boats to the catch. ITQ policies have rationalized the Alaskan halibut fishery completely: the fish stock is thriving, overcapitalization is gone, and the fish catch is spread out over time (Levy, 2010). ITQs have also been implemented in the fisheries of New Zealand, yielding large improvements in the biological status of the stocks (Annala, 1996). There is some general evidence that ITQ systems have been relatively successful in improving fishery outcomes (Costello, Gaines, & Lynham et al. 2008), though other research implies that evidence of the superiority of the ITQ approach is more mixed (Beddington 2007) Scholars and fishery managers continue to work to identify the details of ITQ management that make such systems work most effectively, and to identify what needs to be done to promote more widespread adoption of good fishery management policy worldwide.
References
Acheson, J. M. (1988). The Lobster Gangs of Maine. Lebanon, NH: University of New England Press.
Annala, J. H. (1996). New Zealand’s ITQ system: have the first eight years been a success or a failure? Reviews in Fish Biology and Fisheries. 6(1), 43–62. doi: 10.1007/BF00058519
Beddington, J. R., Agnew, D.J., & Clark, C. W. (2007). Current problems in the management of marine fisheries. Science, 316(5832), 1713-1716. doi:10.1126/science.1137362
Costello, C., Gaines, S. D., & Lynham, J. (2008). Can catch shares prevent fisheries collapse? Science, 321(5896), 1678 – 1681. doi10.1126/science.1159478
Levy, S. (2010). Catch shares management. BioScience, 60(10), 780–785. doi:10.1525/bio.2010.60.10.3
Montaigne, F. (2007, April). Still waters, the global fish crisis. National Geographic Magazine. Retrieved from http://ngm.nationalgeographic.com/print/2007/04/global-fisheries-crisis/montaigne-text.
Worm, B., Barbier, E. B., Beaumont, N., Duffy, J. E., Folke, C., Halpern, B. S., Hackson, J. B. C., Lotze, H. K., Micheli, F., Palumbi, S. R., Sala, E., Selkoe, K. A., Stachowicz, J. J., & Watson, R. (2006). Impacts of biodiversity loss on ocean ecosystem services. Science, 314(5800), 787 – 790. doi:10.1126/science.1132294
Attribution
Essentials of Environmental Science by Kamala Doršner is licensed under CC BY 4.0. Modified from the original by Matthew R. Fisher.
