Less Fishing to Fish More – Strategies to Replenish Fishery Stocks

In many countries, overfishing remains a major issue threatening food security, livelihoods, and conservation. While the future benefits of fishery reform, such as reducing catch rates and protecting more areas are undeniable, many policies do not consider the often-negative impacts on local communities.

Overfishing

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Fishing out the sea - shifting baselines and overfishing

The depletion of global fish stocks has rapidly accelerated over recent decades. This is a result of an increase in fishing effort related to emerging technology able to locate and catch fish over increasingly long distances. Such a drastic increase in harvesting has led to the overfishing of many stocks.

Typically, overfishing refers to fishing mortality or the rate at which fish are caught relative to the overall stock. The United Nations FAO classifies fishers as “sustainable” or “unsustainable” according to the conclusions on which fisheries are overexploited and which are not.

Globally it is recognized that the median fishery is in poor health and likely overfished. Nevertheless, an estimated 32% of fisheries are in good biological, although not necessarily economic, conditions. Estimates show that at least 82% of the wild-caught fish currently come from fisheries with healthy populations. However, a number of confounding factors may limit the accuracy of such information.

From an international standpoint, China is at the top spot in fishing with Peru and the United States following it by a margin, but this can change depending on region and species considered. The most productive fisheries are located in the northwest Pacific Ocean, which supplied the world with nearly 22 million metric tons in 2006. Across fish species, Anchoveta, Alaska pollock, and skipjack tuna are the world's most heavily exploited wild fish species.

In response to increased catch rates and stock depletion, fisheries scientists often look into past records to develop a better understanding of how stocks changed to determine the most effective strategies moving forward.

Consequences of stock overexploitation for fish populations

Historically, fishing stocks have been depleted due to numerous causes. One of the major outcomes of overfishing remains the shifting baseline syndromes, which describes how fishers are catching ever-smaller fish in lower numbers. What used to be productive stocks full of large species has been depleted to only small to medium-sized fish in lowering abundance.

This is primarily due to the fact that fishing selects fish with specific traits.

Firstly, fishers catch large fish so populations become smaller, and only smaller fish remain. These fish will then reproduce when they are younger and smaller, further reinforcing the cycle of decreasing fish size. Secondly, fish with certain behaviors are also more likely to be caught as depending on the method, fishers may catch more timid or more active fish.

Ultimately, fishing activity makes populations less diverse and less productive, decreasing population turnover rate as well as lowering species diversity. This in turn makes fish weaker, as lower diversity makes them vulnerable to environmental or anthropogenic changes, making the remaining fish less valuable to fishers.

To address these consequences, many strategies have been implemented with varying degrees of effectiveness.

Limitations of current policies reducing overfishing

To curb the rapid rates of overexploitation, governments and international organizations are implementing different strategies. From increasing fishing regulations and limitations to closer monitoring of catch rates, several approaches are being used to reduce overexploitation of fish stocks.

In particular, by far the most common policies aim to expand conserved marine spaces to stem the worrying depletion of biodiversity and fish stocks around the globe. However, despite decades of creating protected spaces, the realism and success of protection policies remain faltering particularly for local communities.

This was examined in a new study by a team of researchers from the University of Warwick, UK, led by Marco Haenssgen published in October 2021. The scientists demonstrated the wide range of unintended impacts that conservation efforts have on affected communities.

The research presented a key case study of the Cambodian Koh Sdach Archipelago combined with a cross-country statistical analysis of the impacts of marine conservation across Southeast Asian communities. Findings showed that protecting areas had a mix of positive and negative effects on communities.

From a positive standpoint, communities found economic relief from the slowing deterioration of fish stock, and, in the case of Cambodia as a post-conflict country even experienced improving relationships with the state. However, protected areas also generated social division, heightened livelihood anxiety, and a false sense of economic security related to the fish stocks. The analysis showed that on regional, long-term, scale, community exposure to marine protection schemes was linked to decreasing wealth and increasing child mortality across South East Asia.

Such critical findings demonstrate that protecting areas may not be the single best solution. The authors highlighted by concluding that the target-driven expansion of marine protected areas—now up to 50% of global marine areas—neglects the social realities and livelihoods of affected communities.

Replenishing fish stocks and addressing uncertainties looking forward

The concept of fishing less, therefore, misconstrues the socio-ecological reality surrounding fish stocks. Many studies around the world have emphasized the benefits of reducing catch rates, from crab fisheries rebounding across the US to the reappearance of tuna in UK waters. However, long-term, sustainable productivity relies on understanding complex social, ecological, and environmental dynamics.

This was particularly evident in a study conducted by researchers from the Hawaii Institute of Marine Biology, School of Ocean and Earth Science and Technology, at the University of Hawaii at Manoa. The team discussed the objectives of marine reserves and how to better consider their consequences for local communities.

The authors found there are at least four general objectives for marine reserve design: (1) maximizing conservation, (2) minimizing total reserve area, (3) maximizing reserve compactness, and (4) minimizing socioeconomic opportunity cost (e.g., fisheries revenue). They then compared these objectives to the implementation of bottom-fish restricted fishing areas and how it affected fishers.

Researchers showed that when reserve placements were optimized to provide a maximal opportunity cost, solutions had up to 49% overlap with the restricted fishing areas. This highlights a potential drawback of the bottom-fish restricted fishing areas system concerning socioeconomic impacts. The tradeoffs of conflicting fisheries objectives in reserve design were therefore particularly evident.

Considering such tradeoffs is therefore critical to implanting large-scale management policies. If done effectively, this could drastically improve the outlook of fish stocks globally.

This was shown in a 2016 study by American authors led by Christopher Costello who evaluated the state of global fish stocks, researchers showed that applying sound management reforms to global fisheries in our dataset could generate annual increases exceeding 16 million metric tons (MMT) in catch, $53 billion in profit, and 619 MMT in biomass. Moreover, the authors indicated that with appropriate reforms, recovery can happen quickly, with the median fishery taking under 10 y to reach recovery targets.

Sources:

  • Costello, C., Ovando, D., Clavelle, T., Strauss, C. K., Hilborn, R., Melnychuk, M. C., Branch, T. A., Gaines, S. D., Szuwalski, C. S., Cabral, R. B., Rader, D. N., & Leland, A. (2016). Global fishery prospects under contrasting management regimes. Proceedings of the National Academy of Sciences, 113(18), 5125–5129. doi:10.1073/pnas.1520420113
  • Hilborn, R., & Ovando, D. (2014). Reflections on the success of traditional fisheries management. ICES Journal of Marine Science, 71(5), 1040–1046. doi:10.1093/icesjms/fsu034
  • Oyafuso, Z. S., Leung, P., & Franklin, E. C. (2019). Evaluating bioeconomic tradeoffs of fishing reserves via spatial optimization. Marine Policy, 100, 163–172. doi:10.1016/j.marpol.2018.11.016
  • Pomeroy, R. S., Parks, J. E., & Balboa, C. M. (2006). Farming the reef: is aquaculture a solution for reducing fishing pressure on coral reefs? Marine Policy, 30(2), 111–130. doi:10.1016/j.marpol.2004.09.001

Further Reading

Last Updated: Sep 8, 2021

James Ducker

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James Ducker

James completed his bachelor in Science studying Zoology at the University of Manchester, with his undergraduate work culminating in the study of the physiological impacts of ocean warming and hypoxia on catsharks. He then pursued a Masters in Research (MRes) in Marine Biology at the University of Plymouth focusing on the urbanization of coastlines and its consequences for biodiversity.  

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