How Sustainable Is Sustainable Fishing Really?

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How Sustainable Is Sustainable Fishing Really?

Delving deeper into the issues addressed in Seaspiracy

Overfishing and its impact on marine biodiversity has recently become a hot topic in the media thanks to the recent documentary, Seaspiracy. Seaspiracy is a documentary made by British filmmaker Ali Tabrizi that touches upon these issues, however it has been faced with a lot of controversy from the scientific community due to its sensationalised statements and use of outdated research. Nevertheless, the documentary does highlight a very important point- that industrialised fishing is the greatest threat to marine biodiversity. Further still, the documentary has played a valuable role in bringing this issue to the attention of Netflix’s large viewership and other media platforms as it gained viral success. The documentary creates a narrative that sustainable fishing is not possible, which was received with some discourse from marine biologists, and conservation biologists, like myself. The documentary also questions the credibility of large sustainable fishing and conservation organisations, such as MSC. In this article, I will delve deeper into sustainable fishing and aquaculture to answer the question of “how sustainable is sustainable fishing?” and discuss the integrity of sustainable fishing organisations and the sustainable fishing movement. 

The Issue at Hand

Oceans play an integral role in planetary function, controlling global metrological patterns, carbon cycling and sequestration (Sumaila and Tai 2020). Additionally, marine phytoplankton produces 50%-80% of the oxygen we breathe (NOAA 2021). Fish play a central role in marine food webs. Predator-prey relationships, both between different fish species and fish species and other marine organisms, help maintain the function of marine ecosystems. Marine ecosystems also provide a valuable service to humans, with 3.3 billion people being dependent on the oceans as a source of income and protein (FAO 2020). Nevertheless, human population growth and increasing per capita consumption has led to overfishing to meet global demands (Sumaila and Tai 2020). Unsustainable and destructive fishing practices, such as trawling, illegal fishing, and the use of cyanide and explosives, has led to a global decline in fisheries biomass (Palomares et al. 2020). The implications of declining fish populations and collapsed stocks are not limited to deteriorating economic, cultural, and national security and global food security, but also the collapse of entire marine ecosystems. Overfishing can alter the predator-prey dynamic and fish community structure. The removal of apex predators, such as sharks and tuna, causes a shift in the equilibrium of the ecosystem (Jennings and Kaider 1998). Nevertheless, compiled estimates of the status of global fish stocks from all the available scientific assessments, comprising of roughly 50% of the world’s harvest, indicate that fish stocks are increasing on average. Studies have shown that regions with less-developed fisheries management have poorer stocks, thus highlighting the importance for fisheries management (Hilborn et al., 2020).

What is Sustainable Fishing and Aquaculture?

Sustainable fishing involves fishing practices that respect marine and freshwater ecosystems and considers the reproductive rate of species to maintain the ecological equilibrium and long-term survival of marine and freshwater species. In addition to this, sustainable fishing protects again the capture of juveniles, endangered species, and species without commercial value (FAO 2021). Maximum sustainable yield (MSY) is a measure frequently used in sustainable fisheries and is based on the theory that fish populations increase rapidly before reaching carrying capacity. By maintaining a population at its level of maximum growth, the maximum increase in biomass will be produced in any given year. By removing only the increased biomass the population remains stable and thus sustainable (Stafford 2019). Recent assessments of FAO monitored fisheries in 2017 showed that 34.2% of fish stocks were classified as overfished. The same 2017 assessment estimated that of the assessed stocks in the Western Indian Ocean, 66.7% were fished within the biologically sustainable levels, whilst 33.3% were considered unsustainable, (FAO 2020). Despite progress in some fisheries, the number sustainably fished stocks have decreased from 90% in 1974 to 65.8% in 2017 (FAO 2020). Studies have shown that sustainably managed stocks are more productive (Hilborn et al. 2020), and when managed efficiently, damaged stocks can recover, for example the Patagonian toothfish and the Atlantic Cod (Marine Stewardship Council 2018; Kuparinen and Uusi-Heikkilä 2020). Moreover, ending overfishing has shown to increase fish stock resilience to climate change (Sumaila and Tai 2020).

Aquaculture is the practice of breeding, rearing, and harvesting, fish, shellfish, crustaceans, algae, and other aquatic organisms for commercial purposes. With the increasing demand for seafood, aquaculture helps improve food security, whilst restoring habitat and relieving the pressure placed on wild stocks by commercial fishing (NOAA 2021). The most popular species in aquaculture are salmon, trout, crabs, shrimp, and shellfish, such as clams, oysters, and mussels (Sea Nutrition Partnership 2017). Aquaculture now contributes more than 50% of the fish consumed globally (Cai and Zhou 2019), and is the most resource efficient source of protein (Sea Nutrition Partnership 2017). Aquaculture production is expected to increase by one-third by 2030, producing 109 million tonnes of fish and shellfish, and supplying the majority of seafood-based protein in consumers diets by 2050 (DeWeerdt 2020). In addition to providing food security, aquaculture is a major source of employment, with 20.5 million people employed in the primary sector of aquaculture in 2018 (FAO 2020). Sustainable aquaculture development and effective fisheries management are imperative to support the increasing tends in fish consumption and fisheries production (FAO 2020).

Imperfect Systems

Extensively managed fisheries have proven to decrease pressure on stocks and increase stock biomass, resulting in 65.8% stocks reaching biologically sustainable levels (FAO 2020). Nevertheless, despite growing evidence that when sustainably managed, stocks are able to rebuild and meet target levels, in some regions and countries, this success has not been sufficient enough to reverse the global trend of overfished stocks. Even with 78.7% of landings coming from biologically sustainable stocks, the unequal development in fisheries management demonstrates the necessity to re-adapt polices and measures (FAO 2020). Fisheries policy and management has mainly focus on biological and economic dimensions when trying attain sustainable levels of fishing, whilst social and cultural issues are largely ignored. However, omitting socio-cultural objectives from fisheries policy and management has considerable impacts on fishing communities dependent on ocean services as a source of income and food, such as increased unemployment, outmigration, weaker community structure, and economic hardships. The inclusion of socio-cultural dimensions in fisheries policy is quintessential for successful sustainable fisheries (Urquhart et al. 2014).

As aforementioned, aquaculture is one of the most sustainable food production systems, and produces a greater variety of foods in comparison to other food systems, such as terrestrial meat production, and grain and cereal production (DeWeerdt 2020). Nevertheless, aquaculture also faces some sustainability challenges, such as disease, which was touched upon in the Seaspiracy documentary. Disease causes $6 billion worth of losses each year. When aquaculture is done on a larger production scale, the losses increase considerably. The lack of research into aquatic pathogens makes predicting and identifying diseases difficult, and solutions and treatments can be costly (DeWeerdt 2020). Further downsides of aquaculture include, effluents from aquaculture causing eutrophication, transmission of disease to wild populations, changes in water quality impacting planktonic communities, and the loss of valuable habitats, such as mangroves (Diana 2009; DeWeerdt 2020; Johnston et al. 2002). The loss of mangroves can have detrimental impacts on the environment as they serve as a storm buffer and provide valuable breeding ground and nurseries for common fish stocks. Removing these valuable nursery sites puts added pressure on fish stock health (Johnston et al. 2002).

Overall, contrary to the statements made in Seaspiracy regarding sustainable fisheries, sustainable fisheries and aquaculture do exist and have been successful in mitigating the impacts of overfishing and helping stocks recover. While the system does have its flaws, much like any other food system, research has proven that sustainable fisheries do work in conserving fish stocks (Hilborn et al. 2020; FAO 2020; DeWeerdt 2020)

Can We Trust Sustainable Fishing and Aquaculture Organisations?

Eco-labelling and certification are a popular market-based instruments to indicate products sourced from sustainable fisheries. The Marine Stewardship Council is one of the most well-known eco-labelling programmes, seeking to incentivise fisheries to accept and maintain sustainable fishing practices, and rewarding them with the use of the MSC label (Fig. 1) on their products (Agnew et al. 2014). To be certified by MSC, fisheries must pass the sustainability criteria for the target stock, in addition to having vigorous management systems in place and ensuring the impact of the fishery on ecosystems is minimized (Agnew et al. 2014). The chain of custody plays a crucial role in MSC certification and ensures that foods with the MSC eco-label come from a certified fishery and are not mislabelled (Marko et al. 2011; Martinsohn 2011).

 Seaspiracy raises the question of integrity amongst such eco-labelling programmes, in particular, that the MSC certification is too easy to obtain and therefore not creditable. Seaspiracy is not alone it its critique of MSC and there is a lot of debate amongst the scientific community about the credibility of eco-labelling programmes. Researchers have suggested it is ineffective and fails to set standards that are high enough to see change (e.g.Jacquet et al. 2010; Froese and Proelß 2012; Karlsen et al. 2012). In an assessment of MSC in 2012, Froese and Proelß stated that the MSC certification process needed to be more standardised to give more weight to the stocks’ status. Froese and Proelß went on to state that MSC should be more transparent with their consumers and retailers by indicating products that have come from stocks whose biomass is still recovering (Froese and Proelß 2012). However, this research was challenged by Agnew et al., who stated that the definitions used by Froese and Proelß to assess MSC certified stocks were not consistent with the internationally recognised definitions (Agnew et al. 2013). Other fisheries experts have praised the positive impact MSC is having upon fishery management practices, through creating cooperation and dialogue between stakeholders, and promoting sustainable ecosystem-based fishery management (Kaiser and Hill, 2010; Gutiérrez et al., 2012; Martin et al., 2012). A study done by Gutiérrez et al. indicated that MSC-certified stocks are more likely to meet target points and have lower exploitation rates and higher biomass than stocks that are uncertified. Moreover, the study found that certified stocks were also more likely to attain more conservative targets, in comparison to uncertified stocks. Gutiérrez et al. concluded that the MSC eco-label is a reliable indicator of target stock health and the MSC certification process successfully recognises healthy stocks and fisheries that are meeting sustainable management targets (Gutiérrez et al. 2012).

As you can probably tell, the certification of seafood fisheries is a highly debated topic amongst fisheries scientist. However, as a consumer, ultimately the take away from this is that you should still buy certified seafood because, while eco-labelling programmes such as MSC still need to improve their transparency to consumers and strengthen operations, studies indicate that the percentage of healthy stocks is three to four times higher in certified stocks than uncertified stocks (Froese and Proelß 2012). By supporting eco-labels and sustainably sourced seafood, consumers are promoting this market.

MSC logo. Source:

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