Fishing, arguably one of the most valuable aquatic ecosystem provisioning services to people, takes place in coastal areas, i.e., within Exclusive Economic Zones (EEZs), and in the high seas. EEZs are areas of the global ocean within 200 nautical miles of the coast of maritime countries which claim sole rights to the resources found within them.
In contrast, the high seas are international waters and are therefore ‘owned’ by all citizens of the world. Over the past decades, fishing has expanded into the high seas because of overexploitation of coastal waters, increasing demand for fish driven by increasing world population and rising incomes, provision of government subsidies, and technological innovation.
The increasing exploitation of fish on the high seas has caused concern among scientists, economists, lawyers, governments, non-governmental organizations and the public for several reasons. Inadequate management has led to overfishing of many economically important fish stocks and the fisheries exploiting these resources have been associated with by-catch of threatened or vulnerable species and habitat destruction.
The current status of a number of highly migratory, pelagic species such as tunas and billfishes is particularly worrying. Overall, stocks of tunas and their relatives have declined on average by 60% during the last half century and the majority of these stocks are either fully or overexploited. Deep-sea fishes are also a serious concern.
The depth of the high seas, with little light and food available, provides habitat for fishes that are often long lived and slow growing, characteristics that make them vulnerable to overfishing.
Additionally, despite the technological advances that have allowed us to fish at great depths and the new knowledge we are currently accumulating, the vast majority of the deep ocean remains unexplored and poorly understood. The ecological impacts of deep-sea fishing activities are also largely unknown.
Economic concerns centre on the fact that many fisheries exploiting high-seas resources would not be viable without government subsidies, and socially, only provide jobs and significant incomes to relatively few. From a legal standpoint, both fish and fishers of the high seas are the least protected by international agreements, leaving those working on high-seas vessels vulnerable to exploitative treatment and unsafe working conditions.
The United Nations Convention on the Law of the Sea (UNCLOS) was signed in 1982, when it was thought that the impact of fishing would not be significant in the high seas because of technological limitations and this area's generally low biological productivity.
Now, everything we know about deep-sea habitats and fishing methods such as bottom trawling suggest that the two are incompatible and mounting evidence supports the view that deep-sea ecosystems are in need of urgent protection.
Large marine protected areas (MPAs) in the high seas are of increasing interest and their benefits could be far-reaching. Currently, Regional Fisheries Management Organizations (RFMOs) are implementing fisheries closures to protect vulnerable marine ecosystems in some parts of the high seas. However, there is no effective, coherent management framework for this important part of the global ocean and RFMOs are generally failing to meet the larger mandates under the United Nations and even their own Conventions. As of 2010, two thirds of all stocks of known status under RFMO management were depleted or being overfished.
Importantly, the depletion of high-seas stocks can influence the availability of fish to coastal fleets. We now know that many ocean predators forage in both EEZs and the high seas in the course of a year, exploiting different regions of high prey availability.
Some ‘high-seas’ species therefore straddle EEZ boundaries; hence, mismanaging the high seas also can have direct repercussions on coastal communities and ecosystems. The degree of overlap between the fish currently caught in the high seas and the EEZs has to date not been assessed, but it potentially has important ramifications for fisheries.
White & Costello suggested positive economic benefits from closing the high seas because although the management of fisheries that operate in EEZs is far from perfect, these fisheries are generally relatively better managed than high-seas fisheries.
Our goal here is to examine this idea with empirical fisheries data to assess the impacts of a high-seas closure on global fisheries catches and values, and the economic consequences for individual countries.
First, we analyze global fish catch and landed values to determine how much fish is caught in the high seas versus in EEZs. Specifically, we estimate the global average annual catch and landed values for each species/taxon group caught (i) exclusively in the high seas; (ii) exclusively in EEZs; and (iii) in both the high seas and the EEZs (i.e., straddling taxa).
Second, we examine how the availability of fisheries resources to coastal countries could change following a high-seas closure, and identify the countries that stand to gain or lose, considering potential spillover of biomass from closed areas and lost fishing opportunities in the high seas. We ask what percentage increase in the catch of straddling taxa would make closing the high seas catch-neutral.
The result obtained is compared with a range of potential increases in these catches predicted by White & Costello.
To explore the sensitivity of our results to uncertainty and our assumptions, we simulate various scenarios of increasing total catch of straddling taxa with the closure of the high seas. We then identify winners and losers in terms of catch and landed value by country or political entity under the different scenarios studied.
Finally, we assess the distribution of these benefits under the status quo and with a closure by calculating the Gini coefficient, which we use to measure the extent of landed value disparity among countries or political entities.
You can read a summary of the article here: http://www.thefishsite.com/fishnews/25116/will-a-high-seas-fishing-ban-boost-global-catches
March 2015
