The Tragedy of the Commons

Economist Mancur Olson argued that local governance develops a vested interest in maintaining local resources, whilst the sequential exploitation of roving bandits severs the local feedback and motivation to implement conservation practices. Berkes et al., 2006, examine the effect of roving bandits, and describe it as 'the tragedy of the commons.' This effect has been commonly recognised in the process of globalisation and the increased harvesting capabilities of fisheries.

The tragedy of the commons: A shared, open-pool resource is competitively depleted by harvesters who have no incentive to conserve; the dictating approach is that whatever one individual does not take another will, therefore there is no point in conserving the natural capital, so one may as well gain as much from the resource as one possibly can at the time. 

Commercial fishing was generally recognised as unsustainable after the process became industrialised and the diesel engine was introduced. The catchability coefficient of one given species is expressed as F = qf, where f describes fishing effort and q represents the effectiveness of a gear. The problem with this model is that q is subject to technologial fluctuations, and f cannot be effectively recorded. So there a gaping holes in fisheries science.

The idea of coral reef fisheries being sustainable is laughable: local fishers employ blasting methods and poisions such as cyanide, which actively devastates the habitats that support the communities they seek to fish - Cheilinus undulatus (humphead wrasse) has suffered serial depletion. How can a fishery, which destroys the habitats of the species upon which they rely, ever be considered sustainable?

Ecological Implications

Sequential exploitation of a marine resource or species that will often be a significant conduit for the flow of energy and materials within a community structure naturally poses great risk. One example is the historic exploitation of sea otters for their pelts in the Aleutian Islands (SE Bering Sea) - this key stone predator would control sea urchin populations, but their depletion caused mass deforestation of kelp beds by plagues of sea urchins for over a century. 

Of course, sea urchins themselves were also being harvested; in 1945 only around the east coast of Asia - by 1995 across the world. In Maine, this green sea urchin (Strongylocentrotus droebachiensis) population was rapidly depleted, after the trade-induced increase in demand occurred too rapidly for the local human governance to effectively respond with species conservation intent. 

Simplifying the food webs by rapidly depleting one element or species is the tragedy of the commons, and the resilience of the marine ecosystems towards global/natural threats such as climate change are significantly eroded. 

Management Implications

Often in the past, a local resource will have vanished before a problem is even noticed - further, serial depletions of local stocks may be masked by shifts in exploitation, i.e. changing where you fish, for instance. MPA's and NTAs currently existing are generally too small to sustain processes within the broader seascape - it must be remembered that protected zones are not closed systems. The Great Barrier Reef Marine Park is too small to sustain populations of marine mammals, turtles and migratory sharks.

Addressing the ecological impacts of globalisation and roving bandits means the demand from growth must be matched in alternative ways - substitutions perhaps. According to Berkes et al., 2006, the solution lies, ultimately, with the local populations, but the problem must be approached on multiple scales.

• Continuous monitoring of trade and resource trends to ensure the problem-solving practices are consistent with local behaviour/activities
• Align individual self-interest with long-term health of the resource 
• Compare cost of regulation with cost of losses if no actions were to be taken

Basically, no single approach can solve the problems of roving bandits and globalisation: people are terrible at sharing common-pool resources. Combined approaches may slow down the exploits of roving bandits however, and replace destructive incentives with a resource rights framework that encourages environmental stewardship.

Failure of single-species stock assessment

There are four key broad problems with single-species assessments, as described by Pauly et al., 2002:

• Assessment results have often been ignored on the grounds that they are not precise enough to use as evidence for the economically painful rsetriction of fishing practice: a.k.a. the "burden of proof" problem.
• Assessments have failed and grossly underestimated the severity of stock decline in conjunction with the depensatory impacts of fishing during the decline. 
• Too little attention has been given towards regulatory tactics; reasonable management targets have been produced through modelling and study, but have not been implemented, even in the short-term.
• Cultivation and depensation effects result in recruitment failure after a severe decline, which is associated with changes in feeding interactions, particularly when predators or competitors are removed: this produces an alternate stable state ecosystem with severe implications for fisheries management. 

It all leads back to the tragedy of the commons: increases in fishing-fleet capacity advanced the overcapitalisation of the world's fisheries, particularly due to their open-access nature. Common-pool fisheries (amongst most resources) are not managed cooperatively. The basic theory of bioeconomics suggests that if fleet reduction (reducing the amount of active fishing vessels) is done properly, then an increase in net benefits from the resources would be produced. Taxing the net benefit increase from the remaining fishers could then be used to support fishers who had to stop fishing. 

Instead, what is currently happening is that taxes are taken externally from the fishing sector in order to maintain biologically unsustainable levels of fishing, and this is supported by the public at large because it seems that there is this underlying general opinion that the oceans will yield as much as we need - just because we need it. What we actually get is a variety of different forms of extinction.

Local extinction: Defaunation can drive species in to local extinction, and is particularly severe amongst large pelagic fishes, 90% of which experience range contractions. This range contraction often results in the direct elimination of vulnerable subpopulations. For instance, consider the Asian tigers, who have lost 93% of their historical range, while the tiger shark, which its much less extreme range constriction, still roams the world's oceans (McCauley et al., 2015). 

Ecological extinction: Reduction in population abundance can filter through an entire trophic system; for example when marine vertebrates have decreased in abundance by 22%, fishes have declined in aggregate by 38%, and baleen whales by 80-90%. These declines are termed ecological extinctions, and on land this process leads to the phenomenon of 'empty forests.' Ecological extinction of forest fauna alters tree recruitment, plant dispersal and causes population explosions of small mammals. 

Commercial extinction: This occurs when species drop below an abundance level where they can be economically harvested - it might be considered ironic that a commercial extinction might be what saves a species, from a "you're dead to me" perspective. This is not always the case and not all species are so lucky to be spared once they stop being economically viable - some species may become highly prized as soon as they become rare; their value increases as the anthropogenic Allee effect takes grip.