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Overfishing refers to a situation when fish are caught faster than their stocks can be replenished, leading to an overall depletion of fish populations that may result in their collapse. In 2018, the total global capture by fisheries reached the highest level ever recorded at 96.4 million tonnes – an increase of 5.4% from the average between 2014-2017. Not only does overfishing pose threats to the marine ecosystems, it also affects many people directly – especially those who greatly rely on fishing to make a living. Here are 19 overfishing facts you need to know.


19 Overfishing Facts

1. Fish and other seafood products provide vital nutrients for more than three billion people – or nearly 40% of the world’s population – and supply an income for 10-12% of the world’s population.

2. According to the World Bank, almost 90% of global marine fish stocks are fully exploited or overfished.

3. Global fish and seafood production has quadrupled over the past 50 years, and the average person now eats almost twice as much seafood as half a century ago.

4. The world’s largest fish producer and exporter is China while the EU is the world’s largest importer of fish and fish products. 

overfishing facts

Source: Our World in Data

5. Between 1961 and 2016, the average annual increase in global food fish consumption (3.2%) outpaced population growth (1.6%).

6. As part of the United Nations’ 17 Sustainable Development Goals (SDG 14), the UN and FAO are working towards maintaining the proportion of fish stocks within biologically sustainable levels. 

7. The percentage of fish stocks within biologically sustainable levels in 2017 was 65.8%, far lower than that of 1990’s 90%.

8. Over the past 40 years, marine species have seen a decrease of 39%.

9. Illegal, unreported and unregulated (IUU) fishing represents 12-28% of fishing worldwide- around 11-26 million tonnes of fish. 

10. Another problem related to overfishing is bycatch, whereby large amounts of unwanted sea animals are captured during the fishing for a particular species and then are discarded as waste, causing the unnecessary loss of billions of fish and sea creatures. 

11. About 38.5 million tonnes of bycatch results from the practice each year.

12. In a programme co-organised by the Global Environment Facility (GEF) and FAO, the promotion of non-entangling and ocean-friendly fish aggregating devices (FAD), which are floating devices that are used to lure fishes, has helped to greatly reduce levels of bycatch. Adjusting fishing practices through this programme reduced the mortality rate of marine mammals caught by Pakistani gillnet fisheries in the northern Arabian sea from 12 000 in 2013 to less than 200 in 2018. 

13. Among OECD countries, Italy gives the biggest subsidies per catch ton.

overfishing facts

Source: The World Bank

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14. One of the most highly-caught fish is tuna, which reached its highest levels in 2018 with over 7.9 million tonnes. 

15. The depletion of fish stocks greatly affects the fishing community; about 59.5 million people work in the primary sector of fisheries and aquaculture, according to a 2018 study.

16. Subsidies from the government (for fuel, fishing gear and building new vessels) often benefits large-scale fishing companies which indirectly encourages the use of fuel-intensive fishing and destructive fishing practices eg. deep-sea trawling. 

17. Researchers found that Illegal, unreported and unregulated (IUU) fishing are sometimes related to more serious problems like human trafficking and slavery at sea. 

18. The Code of Conduct for Responsible Fisheries is a foundational agreement among the 194 FAO members nations on the regulated use of fisheries and aquaculture resources. In a 2018 questionnaire, most members, regional fishery bodies (RFBs) and selected NGOs expressed a strong opinion on improving management in marine and inland fisheries. 

19. The last of the facts about overfishing is that the 2030 Agenda by FAO targets the monitoring of fisheries and aquaculture in achieving food security and nutrition. It also aims for the sector’s use of natural resources in a biologically, economically and socially sustainable way.

EO Position: These facts illustrate the urgency with which we must treat the consequences brought by overfishing and support sustainable aquaculture. As consumers, we should opt for sustainably certified seafood (usually with the Marine Stewardship Council logo) and be more informed about the origin of our food to make sure it is caught in a sustainable way. Fish stocks are currently being fished at an unsustainable rate but if no-fish zones were implemented strategically around the world, we could have all the fish we’d ever need. 

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Ecuador has sounded the alarm after its navy discovered around 260 mostly Chinese-flagged fishing vessels in the ocean surrounding the Galápagos islands. The fleet, found just outside a protected zone, raises the prospect of damage to the protected region’s diverse ecosystem and marine life.

Chinese Fishing Fleets in the Galápagos

The fleet was spotted with satellite imaging on the borders of the Galápagos Protection Zone. The fleet was found between the boundaries of the zone and Ecuador’s territorial waters, an area that serves as a major migration route for sea creatures, including many endangered species.

Former environment minister Yolanda Kakabadse says, “This fleets’s size and aggressiveness against marine species is a big threat to the balance of species in the Galápagos.” Kakabadse and Roque Sevilla, ex-mayor of Quito, have been put in charge of designing a ‘protection strategy’ for the islands. Sevilla says that diplomatic requests would be made to request the fleet’s withdrawal. “Unchecked Chinese fishing just on the edge of the protected zone is ruining Ecuador’s efforts to protect marine life in the Galápagos,” he says. He added that the team would also seek to enforce international agreements that protect migratory species. 

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chinese vessels Galápagos
A Marine Traffic image showing the fishing fleets, represented by the orange arrows at the bottom left, as of July 27 2020 (Source: Hong Kong Free Press).

Chinese fishing vessels come every year to the seas surrounding the Galápagos islands, a UNESCO Heritage Site, but this year’s fleet is one of the largest seen in recent years. The Galápagos Marine Reserve has one of the world’s largest concentrations of shark species, including the endangered whale and hammerhead sharks. UNESCO describes the islands as a ‘living museum and a showcase for evolution’. 

Ecuador is trying to establish a corridor of marine reserves between Costa Rica, Panama and Colombia to seal off important areas of marine diversity. Kakabadse says that efforts will also be made to extend the exclusive economic zone to a 560km circumference around the islands. 

The Ecuadorean navy has been monitoring the fleet since it was first spotted in the week of July 20. The country’s defence minister Oswaldo Jarrín says, “We are on alert, conducting surveillance, patrolling to avoid an incident such as what happened in 2017.”

The incident in question refers to the capture by the navy within the Marine Reserve of a Chinese vessel, which was found to be carrying 300 tons of marine wildlife, mostly sharks. 

UPDATE AUGUST 11: Ecuador’s navy is conducting surveillance of the Chinese fishing fleet, which has grown to 340 vessels. China has promised a “zero tolerance” approach to illegal fishing and has proposed a moratorium on fishing in the area between September and November. The fishing fleets usually leave the area before that period.’

UPDATE SEPTEMBER 18: According to environmental protection NGO Oceana, the fleet are mainly fishing for squid, a vital part of the diet of endemic creatures including hammerhead sharks, as well as tuna. It has also been determined that the vessels disabled their public tracking devices, typically done to hide illegal activities.

This is a developing story. Follow Earth.Org for more updates. 

The Consumer Council, the consumer watchdog of Hong Kong, reported various levels of metallic contaminants in samples of canned fish that could pose health risks if eaten in excess. The watchdog also found that the contaminants reported were not present in a similar study conducted in 2004.

The council examined 46 samples of canned fish in Hong Kong, all of which are available on the market. In particular, 19 types of sardines, 20 types of tuna, and seven kinds of dace fish were tested, with prices ranging from HK$7.8 to HK$149 per can. 

On average, the sardine samples were found to contain the highest amount of cadmium- a chemical which can lead to chronic poisoning or irreversible kidney damage if consumed in copious amounts- followed by tuna. The dace fish samples did not contain any cadmium. 

The Food Adulteration Regulation, which is yet to take effect in Hong Kong until November, states that the maximum amount of cadmium that is safe for consumption is 0.1 mg. Two of the sardine samples, which were imported from Thailand, contained 0.11 to 0.13 mg per kg of cadmium. 

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Half of the sardine samples also contained polychlorinated biphenyls (PCBs), a carcinogenic harmful to humans as classified by the International Agency for Research on Cancer. 

More than 70% and 10% of the sardine and tuna samples respectively contained inorganic arsenic- a toxin which, following prolonged exposure, can cause neurological and cardiovascular diseases. However, the samples contained between 0.04 to 0.08 mg per kg, below the maximum safe limit.

Methylmercury was identified in 18 of the 20 tuna samples, with levels ranging from 0.06 to 0.28 mg per kg- within the 0.5 mg per kg upper limit in Hong Kong. Consumed in excess,however, methylmercury can hinder foetuses’ nervous system development. “Foetuses and children are more prone to the adverse health effects posed by methylmercury as their brains are still developing. Excessive intake would lead to a decrease in intelligence of toddlers,” warned the council in their latest publication

All of the seven types of dace fish samples were found to have levels of metallic contaminants and PCBs well below the maximum cut-off guidelines. 

The 2004 Study

In 2004, a similar study by the Consumer Council examined nine types of sardines and eight types of tuna and found levels of arsenic that complied with Hong Kong’s food regulations at the time, although cadmium, lead and PCBs were not found. 

Levels of methylmercury were found in four samples of canned tuna in amounts well below the safety limit in mainland China, the regulations of which were more stringent than those in Hong Kong at the time. The council did not express concern over the methylmercury content in canned fish. 

Gilly Wong Fung-han, chief executive of the council, says, “the latest study reflects the severity of environmental pollution in the food chain, which in turn shows the increased contamination in canned fish.” 

Cause for Concern 

Nora Tam Fung-yee, chairwoman of the Consumer Council’s research and testing committee, says that consumers needn’t be worried about eating canned fish in general, as ‘you have to eat a huge amount over a long period of time to be adversely affected’. 

Wong noted that consumers should not completely cut canned fish out of their diet as it is an ‘easy source of high protein’, but they should rather limit intake and eat in moderation. She however advises that pregnant women avoid canned fish so as not to risk harming foetuses.

What Does this Mean for the Future of Food Security?

Hopefully, following the enactment of Hong Kong’s Food Adulteration Regulation, the fishing industry and supermarket suppliers alike will become more strict regarding which canned fish products they make available on the market. 

In order to strengthen food security, fishermen should designate fishing sites which lack pollution, are maintained to a high degree and that care for the health of the fish and their food chain. 

Consumers should also be made aware of the potential risks of consuming canned fish to ensure they make an informed decision. 

As metallic contaminants accumulate in the fatty tissue of fish, the safety of other marine animals, who share the same ecosystem and who may rely on fish as a food source, is an additional factor to take into consideration. Humans should either cut back on their intake on fish (and meat in general) so as to avoid contamination, or address the causes of the contamination in the first place, including pollution and waste water run-off.

According to a study published in the journal Science, approximately 60% of fish species will struggle to reproduce in their current habitats by 2100 under the escalating pressures of the climate crisis. The study highlights how previous investigations, analysing the reproductive nature of adult fish, have underestimated the effects of the climate crisis on economically and ecologically important species. How will this impact global fish stocks, and what role does overfishing play in accelerating the reduction of fish populations? 


The study found that the rise in the Earth’s core temperature will have a significant impact on fish stocks worldwide. The researchers investigated whether saltwater or freshwater fish are more sensitive to heat across all climate zones. They examined 694 fish species’ tolerance to various temperatures, followed by an analysis on which of the species in particular are more resilient to temperature fluctuations. 

It was noted that the temperature of the water largely determines the success of reproduction, demonstrating that fish species are particularly attuned to changes in their environment- be it oceans, lakes, ponds or rivers. The researchers attributed this finding to the oxygen-limitation hypothesis, which postulates a mechanistic link between the physical development of an organism in aerobic capacity and tolerance to temperature extremes. Oxygen is a huge factor to consider when discussing energy expenditure as the warmer the climate, the more oxygen is required to function. If failure to adapt to this rise in temperature occurs, fish species are at risk of experiencing adverse health effects, such as cardiovascular collapse. 

“Our findings show that, both as embryos in eggs and as adults ready to mate, fish are far more sensitive to heat than in their larval stage or sexually mature adults outside the mating season,” explains Flemming Dahlke, a marine biologist at the Alfred Wegener Institute and lead contributor of the study. The explanation behind such variability lies in the anatomy of the fish during different respective life stages: fish embryos do not have the facilities, such as gills, to allow for greater oxygen intake, and are therefore put at a significant disadvantage when it comes to survival; mating fish require more oxygen to accommodate for the increase in body mass and energy required to successfully reproduce. The strain such requirements have on the fish pose significant health risks that their bodies are essentially unable to manage. 

Furthermore, the researchers explained that if the rise in temperatures is limited to 1.5 degrees Celsius by 2100, 10% of fish species would struggle with reproduction, or would be forced to migrate to cooler climates. However, if the Earth’s core temperature increases by 5 degrees or more, up to 60% of fish species would be affected. The current projection is a global rise in 3 degrees by the end of the century.

Although some fish species may be able to adapt, the majority would not be as fortunate- particularly where size or geographical location might inhibit locomotion or spawning abilities. 

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The Effects of Overfishing on Marine Ecosystems 

According to the Food and Agriculture Organisation of the United Nations (FAO), 33% of fisheries are overfished, and, collectively, 90% of the world’s fisheries are either overfished or fully exploited. This poses a significant threat to the infrastructure and efficiency of marine ecosystems. 

A decrease in fish diversity as a result of overfishing alters nutrient recycling in marine ecosystems, ultimately having a cascading effect on species situated lower in the food chain. Fish species contribute to this process in varying degrees depending on the rates at which they excrete essential nutrients, such as nitrogen and phosphorus, which affects other marine organisms. Once excreted, these nutrients are readily available to primary producers, such as plankton and algae, who depend on nitrogen and phosphorus to grow. Disturbances to the process of nutrient cycling affects the growth of primary producers and of other organisms who depend on these producers for food and therefore survival. This vicious cycle, starting from the top-down, further emphasises the importance of fish species and their need to reproduce. 

Illegal Fishing 

According to a study published in the journal PLoS One, illegal fishing accounts for up to US$23.5 billion worth of seafood every year. The PEW Charitable Trusts notes that, ‘by volume, illegal and unreported fishing accounts for 11 to 26 million tons of fish every year; that means up to 1 800 pounds of seafood are stolen from the seas every second’.   

Another study found that ‘Illegal and unreported catches represented 20–32% by weight of wild-caught seafood imported to the USA in 2011’. Illegal, unreported and unregulated (IUU) fishing pillages the ocean, depletes fish stocks and negatively impacts conservation efforts. In addition to affecting fish species worldwide, IUU fishing also represents a major loss of revenue, particularly to some of the poorest countries in the world where dependency on fisheries for food, livelihoods and revenues is high. 

Future Investigations 

The above data demonstrates the many downfalls overfishing and IUU fishing has on the environment, economy, and ecosystems across the world. The investigation demonstrates a deeper understanding on how fish species are being affected by the pressures of the climate crisis and the extent to which habitat loss is determined by climate-induced changes of ecosystems. The analysis will assist in improving projections on the future of worldwide fish stocks- painting a clearer picture for reports like the Special Report on the Ocean and Cryosphere in a Changing Climate produced by the IPCC

The assessment is conservative, and does not factor in the many other impacts the climate crisis has on marine life, such as ocean acidification that will impact vulnerable aquatic species.  Expanding on the investigation would therefore provide worthwhile findings that will serve to benefit the maintenance of marine ecosystems worldwide, as well as enhance what is currently understood about the dual relationship between fish species and how they reproduce amid rising temperatures.  

Climate change is doing something unusual to the fish in our oceans: As water temperatures rise, this causes fish to morph in size. Some shrink, but others grow.

How Does Climate Change Affect Fish?

In a new study published in Nature Ecology & Evolution, researchers analyzed data from more than 10 million visual survey records to understand the phenomenon of fish shrinking and growing in size in response to climate change, and to consider the effects on the marine environment and the management of fisheries.

Similar studies have tended to look at species that are commercially fished, mainly because there’s plenty of data on them. This investigation, however, looks at a wide range of fish living in the waters all around Australia.

“We looked at all species,” Asta Audzijonyte, research fellow at Australia’s Institute for Marine and Antarctic Studies and lead author of the study, told Mongabay. “The beauty of this study is that we didn’t choose any species selectively. We looked at 335 species, which were all of the species that we had enough data on, so I had that criterion as some kind of filter.

“That included tiny species … to giant fish and sharks, included species that are fished, but mostly species that are not fished, like puffer fish.”

The researchers were able to gather a large amount of data thanks to a reef monitoring program that has run for three decades, as well as a rigorous citizen science program.

“The citizen science component is the most exciting part,” Audzijonyte said. “About 100 divers … volunteered their time to collect all of this information. There was a standard method to how they do these underwater surveys: they dived and they had a transect of 50 meters [164 feet] … and they recorded all of the species they saw” within this span.

The researchers investigated size in two main ways. First, they looked at fish of the same species living in different locations around Australia, and analyzed how warmer or cooler waters in the species’ natural distribution affected their size. Second, they examined how fish species living in one location would be affected by climate change-induced warming over time.

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climate change fish size
An infographic showing differences in fish size throughout a species’ distribution. Image by Asta Audzijonyte.

Why Are Fish Shrinking in Sizes?

Changes in temperature through time, in response to climate change, had much stronger impacts on size than changes of temperatures in space, throughout the species’ natural distribution, Audzijonyte said.

“Different populations living (for a long time) at warmer or cooler parts of species natural distribution were about 4% different in body length for each degree of temperature change,” she said. “However, when water temperature changed through time in one place due to global warming, a population experiencing this warming was changing by nearly 20% for 0.5 degree [Celsius, or 0.9° Fahrenheit] of warming, observed over the last two decades.”

To Audzijonyte, one of the most surprising findings was that some fish grew, instead of shrank, in response to warming waters.

“If you looked at my earlier papers, they basically said that we expect species to get smaller with warming because that’s the generally accepted belief, and what we saw from commercially fished species,” she said.

What she and her colleagues ultimately found was that 45% of species grew in response to climate change, while 55% got smaller. Moreover, it was the bigger fish that tended to get bigger, and the smaller fish that usually got smaller.

“One of the reasons this study is important is that it shows the complexity of species’ responses to warming in our oceans,” Nicholas Payne, assistant professor in zoology at Trinity College Dublin’s School of Natural Sciences and co-author of the study, said in a statement. “Much of our understanding of the temperature-size relationship comes from the laboratory; taking our predictions to the wild shows us there is a lot we still need to learn about this hugely important phenomenon.”

The implications for these size changes are not fully understood, but these fluctuations would certainly have an impact on the marine food web, Audzijonyte said.

“As fish get smaller, they’re more vulnerable to predation,” she said. “It means that they will have a higher mortality from predators. All of these sized-based interactions will be changing quite a lot, and we don’t know what that means. We need to study that.”

This article was originally published on Mongabay, written by Elizabeth Claire Alberts, and is republished here as part of an editorial partnership with Earth.Org. 

Unsustainable fishing threatens many aspects of human life, degrading ecosystems and creating socio-economic instability for many communities across the globe. The Food and Agriculture Organization of the United Nations (FAO) has predicted an 11% decline in oceanic productivity of tropical zones by 2100, a worrying notion considering the ever-growing global population and dwindling marine populations. One animal suffering from this decline is the Queen Conch, the national emblem of the Bahamas. 

Unsustainable Fishing: Facts

Currently over 53% of the world’s fisheries are being overexploited, according to World Wide Fund (WWF), due to unsustainable practices across the world. Unsustainable fishing not only affects the target catch, but also destroys habitats, alters food web dynamics and damages the seafloor, as documented by the Ocean Health Index (OHI). With over 40.3 million people across the globe currently working in capture fisheries (FAO), the decline in fish stock could put the stability of these jobs at risk. 

A country hit particularly hard by unsustainable fishing is The Bahamas. Of particular concern in the last decade are the diminishing numbers of the Queen Conch, a species of mollusc that serves as an iconic centrepiece in Bahamian culture and cuisine. The conch, which can grow to 30cm and live for as long as 40 years, holds an indisputable place in the hearts of the Bahamian people.

The cultural importance of the mollusc has been evident since the Independence of the Bahamian archipelago in 1971, when it became the national emblem. Since then, conch has formed a staple in everyday life for the Bahamian people, being served in most restaurants throughout the country in fritters, burgers, stews and salads. Additionally, conch shells are often fashioned into jewellery and trinkets, providing an income for local communities in tourist hotspots.

A group study by the University of Hamburg details many interviews with locals who recall childhood memories of diving for conch with their families. Nearly 93% of those interviewed admitted to consuming conch regularly, which indicates a huge market for conch without crossing ocean lines. Statistics prove this, with the Bahamian government’s indication that 80% of all conch harvested is consumed in-country.

Financially, the conch industry brings in US$3.3 million a year for the Bahamian economy, as documented by The Bahamas National Trust. Since 1970, the demand for conch has risen from 750 tonnes a year, to over 4178 tonnes, concerning figures as populations of conch are depleting. A recent study by Allan Stoner and his colleagues found evidence of ‘collapsing populations’ of the molluscs across the Berry Islands, Andros Island and Lee Stocking Island. 

The reason for conch depletion is relatively clear. From a biological standpoint, conchs reach sexual maturity at around 3-5 years of age, with a shell lip at least 15mm thick. Conchs harvested prematurely as adolescents are unable to reproduce at a rate fast enough to keep up with the unsustainable rates of fishing. With the premature deaths of adult conchs, the rate of reproductive failure is increasing. The continued abuse of this animal is threatening the livelihoods of many law-abiding fishermen. It is estimated by the National Geographic that if the conch industry was to collapse, it could result in over 9 000 Bahamian fishermen losing their jobs, nearly 3% of the country’s population.

Measures have been taken to aid in the restoration of the conch population. Currently, conchs are protected under the Convention of International Trade Of Endangered Species of Fauna and Flora (CITES), which sets guidelines to encourage the species’ recovery. These guidelines focus on limiting harvesting to licensed vessels and banning the use of scuba diving for collection. As well as this, molluscs must exhibit a ‘well-formed flaring lip’ on the shell to be legally harvested. Of course, this is highly subjective which can perhaps be to blame for the lack of success in restoring conch populations.

While there is acknowledgement that the conch is becoming a progressively scarce resource, with over 60% of Bahamian locals in Stoner’s study classifying the conch as endangered, more education is needed to inspire and push for changes in outdated, ineffective policy. Without people fighting against illegal overfishing, the problem will exacerbate, and a deeply symbolic national treasure could be lost. 

Discussions are being had around the implementation of a closed conch harvesting season, which would involve set periods of the year where conch can be harvested in an attempt to allow the population adequate time to recover. Jamaica, not far from The Bahamas, has already put into force a closed season, having made the harvesting and consumption of conch illegal between March 1 2019 and January 31 2020. It is perhaps too early to determine if this has been beneficial.

However, the idea of a closed harvesting season has been met with backlash by local Bahamian fishermen. In a national survey conducted about such a proposal in August 2019, fishermen and vendors rejected the arguments for a closed season, with many saying that they will be out of work for many months of the year and that people will not wait ‘months to eat fresh conch’. 

“What are they are going to do if they can’t find jobs out there during the closed season. You’re taking fishermen off the water to come on land when they got families to feed,” one fisherman said.

How to stop unsustainable fishing?

With overfishing becoming a more prominent concern in recent decades, changes to current behaviours are crucial. Community- government collaboration and public education is key to ensuring that the oceans are able to support marine life as well as economic activity for generations to come. Implementing a sustainable way of fishing must be of paramount concern, before the stacks of dumped conch shells so commonly found across the Bahamas are the only reminder of a once-booming industry. 

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