Overfishing is not just a modern development but has been continued for centuries and as unfortunate as it may sound, it has spread all across the globe.

The kind of technology and equipment we use today, it seems like as if we have waged war against the ocean species to exterminate them, but in the end, it could be a case of digging our own grave.  

According to the United Nations Food and Agricultural Organization (FAO), 70% of the world’s fish stocks are under considerable pressure being “overexploited” or “significantly depleted” due to the impact of overfishing.

Let us see 10 major effects of overfishing with facts & statistics to know the gravity of it and have a grasp of its impact on the oceans, marine life, the ecosystems, and ourselves.

1) Species Extinction

Most of the Earth’s surface is covered by ocean and given its vastness, it’s daunting to know precisely the number of species that live there, let alone knowing exactly the extinct species due to direct & indirect effects of overfishing.

However, research warns that the number of species in the ocean is declining as oceans are being industrialized for food, and the number of marine extinctions can rapidly increase due to deteriorating ocean ecosystems.

According to one recent study, 15 animals have been documented as being disappeared completely from the oceans and one such example is the Steller’s sea cow.

Within 27 years after discovering the animal by Europeans in 1741, the mammal was easily hunted into extinction by fur traders, seal hunters, and others for its meat, fat, and hide.  

Baiji a freshwater dolphin was also another classic example of extinction caused by humans. The dolphin was rapidly hunted for its flesh and skin, where 6,000 Baijis known to have lived in the 1950s came down to 13 in 1997 quickly becoming scarce until the species was declared as extinct or at least functionally extinct.

Extinct Fish & Other Marine Species Due to Overfishing & Hunting

1. Blackfin cisco
2. Steller’s sea cow
3. Gravenche
4. Blue walleye
5. Baiji
6. Caribbean monk seal
7. Houting

Source: https://www.iucnredlist.org  (International Union for Conservation of Nature)

2) Depletion of Fish Population & Endangering Species

via GIPHY  video credit: Allan Ecleo [CCPL 3.0]

Tonnes of fish are drawn out of the sea on a daily basis to an extent of hindering the ability of species to replenish their population levels.

In an international scientific study released by the Science Journal states that one-third (approx.) of all fishing stocks globally have been depleted and at this rate, all fish stocks worldwide could be fully exploited.

According to The Food and Agriculture Organization of the United Nations data, the total capture fisheries production globally was estimated to be 90.9 million tonnes in 2016.

Many species of sharks, rays, and skates are now being risked with extinction, mainly due to overfishing.

Sharks, in particular, are threatened due to a cruel practice called shark finning where they slice off the shark fins and toss them back to the water while still alive making the sharks sink back to the bottom. Unable to swim they die of blood loss and get eaten by other fish, resulting in a painful death.

Approximately 100 million sharks are killed globally each year and the main incentive for this trade is coming from the demand for shark fin soup.

Bluefin tuna, a fish that ranks higher in its food chain has also suffered a fatal decline being endangered and fished to the brink of extinction with advanced fishing methods and high demand for the species by rich sushi lovers.

Other vulnerable species due to commercial overfishing are chinook salmon (some populations), cassava croaker (declined by 30% – 60% over the past 10 years), Atlantic cod, and porbeagle (a mackerel shark).

Critically Endangered Marine Species Due to Targeted Commercial Fishing

1. Southern bluefin tuna
2. Common skate
3. European eel
4. Totoaba
5. Smoothback angelshark
6. Sawback angelshark
7. Striped smooth-hound
8. Chinese bahaba
9. Daggernose shark
10. Pondicherry shark

Endangered Marine Species Due to Targeted Commercial Fishing & Hunting

1. Atlantic bluefin tuna
2. Blue whale
3. Whale shark
4. Sei whale
5. North Atlantic right whale
6. Great hammerhead
7. Scalloped hammerhead
8. Japanese eel
9. Zebra shark
10. White-spotted Izak
11. Senegalese hake
12. Narrownose smooth-hound
13. Undulate ray
14. Bottlenose skate

Source: https://www.iucnredlist.org  (International Union for Conservation of Nature)

3) Disruption of Marine Food Web & Food Chains

A growing body of scientific evidence shows the dangers for the predators in high volumes of forage fish overfishing (prey fish) and every other living organism involved in the food web and food chains.

As you can see in the image above, it’s much easier to understand with some common sense, how interruptions of human activity can cause adverse effects to the species of a marine food web.  

Forage fish typically make up 30% or more of the total quantity of fish caught annually which can negatively affect the predator fish species.

This is quite evident in the case of the Southern Resident orca population declared endangered in 2005. One study suggests that orcas were starving due to the overfishing of Chinook salmon which comprised roughly 80 percent of the whales’ diet.

On the other hand, when the population of predatory species (such as sharks and tuna) is declining, it results in an increase of forage fish which in turn can cause an increased growth of algae which threatens the coral reefs’ health and a disruption to the ecosystem.

The reason for the growth of algae is the diet of forage fish that consume invertebrate herbivores such as snails and crustaceans that keep control over the harmful growth of the algal community.

4) Increased Damage to the Seabed

Fishing gear has a major effect on the seabed, especially bottom trawling which has a substantial impact on some ecosystems existing at the bottom.

Bottom trawling is a method where fishing vessels use large, heavy nets to catch fish & other seafood species that inhabit the bottom of the ocean.

These nets can weigh several tons and dragging them cause severe damage to the seafloor such as deep-sea corals & sponges, seafloor life, nursery & spawning grounds for many species, and breakdown of waste substances

Bottom fishing is not something new and has been there for over a century, and it is responsible for an annual account of over 30 million tonnes of global fishing harvest which gives the highest yield than any other method.

5) Effect on Coral Reefs

Though the total area of the world’s coral reefs is less than 1% of the whole area of oceanic environment, the variety of life supported by coral reefs is similar to some of its terrestrial counterparts such as the Amazon and the reefs are habitats to 25% of all marine life.

Yet fishing gear such as spearguns, fish traps, beach seine nets, gill nets, and ghost nets can damage coral reefs severely.

Further non-selective gears, such as nets and traps, may reduce herbivorous fish that consume algae that could potentially cause an overgrowth of algae which in turn can stifle the reefs.

Other fishing techniques such as blast fishing and cyanide fishing are also major threats to coral reef ecosystems that can cause coral reef degradation and increase mortality.

6) Secondary Effects (bycatch) on Marine Species

Whenever there is commercial fishing, there is bycatch, the incidental capture, and loss of non-targeted marine animals and recognized as a major threat to marine biodiversity worldwide.

When extremely strong nets and lines are set, spreading over thousands of miles, it’s inevitable such fishing gear would be a destructive force for undesired marine species being incidentally entangled & captured.

Bycatch affects the loss of billions of fish, along with marine turtles, seals, whales, dolphins, seabirds, invertebrates, corals and many other species. Global bycatch is estimated at 7.3 million tonnes.

Extinct & Endangered Marine Species, Incidentally Affected by Commercial Fishing

1. Vaquita
2. Giant devil ray (devil fish)
3. New Zealand sea lion
4. Hawaiian monk seal
5. Blue whale
6. Baiji
7. West Indian Ocean coelacanth
8. Green sea turtle
9. North Atlantic right whale
10. Whale shark
11. Sakhalin taimen
12. Sei whale
13. Taiwan angelshark
14. Galapagos penguin
15. Scalloped hammerhead
16. Great hammerhead
17. Sea otter
18. Marine otter
19. Australian sea lion
20. Yellow-eyed penguin
21. Finless porpoise
22. Senegalese hake
23. Undulate ray

7) Environmental Pollution

It was estimated in 2016 that there are approximately 4.6 million fishing vessels in the world and according to a report from European Commission, for each ton of captured fish, 1.7 tons of carbon dioxide (CO2) is emitted.

In another report from Oceana, an international organization focused solely on protecting the oceans says, the global fishing fleet is 250% larger in capacity than what is required to capture the ocean’s sustainable produce.

In the year 2000 worldwide commercial fisheries had burnt almost 50 billion liters of fuel to harvest & process around 80 million tons of fish and other seafood products.

The reasons for such a large amount of fuel consumption by commercial fisheries are due to the activities taking place in modern fishing vessels such as onboard processing, refrigeration, etc. and mostly by vessel propulsion.

Various human activities have contributed significantly to elevate the levels of greenhouse gases which is a leading cause of global climate change that has already triggered catastrophic consequences. The fishing industry is no exception in this regard, having its share of contribution towards rising temperatures.

Research has further shown that fishing debris such as ghost nets, buoys, ropes, and lines, are among the debris appear in the oceans and vessel spillages such as oil, chemicals and other harmful organisms due to faulty ballast water and bilge water management systems can hurt marine life & the ecosystems severely.

8) Increased Risk of Diseases to Marine Life & Humans

Other than directly being exposed to fish with toxins such as mercury, PCBs, cadmium lead and diseases such as viral hemorrhagic septicemia (VHS), Ichthyophthirius multifiliis (ich) and whirling disease, the pollution we discussed above can further cause many other types of diseases to marine life and humans.

Overfishing & pollution by fishing industry may cause harmful algal blooms (HABs) that can release extremely dangerous toxins which have already affected people and animals with illnesses such as ciguatera fish poisoning (CFP), neurotoxic shellfish poisoning (NSP), paralytic shellfish poisoning (PSP), etc.

Further harmful algal blooms can create dead zones in the water, complicate & raise operating costs for drinking water management & treatment causing issues for everyone that depends on clean water.  

Declines of fish species due to overfishing which rely on snails as a source of food that carry disease-causing parasites have given rise to the incidence of snail fever (schistosomiasis) in Africa.

Spillage of ballast water & bilge water that may include thousands of harmful organisms, oil, chemicals, particles, and other waste materials could spread diseases to many parts of the world, poisoning & threatening people, animals, and plant life.

9) Economic & Financial Impact

A classic example which shows the dangers of reliance on fishing as a source of income & livelihood was the case of Newfoundland. When cod was abundant in the Northern Atlantic Ocean, people used the cod stock as a means of support to thrive.

With the use of new technology, the cod population was depleted dramatically despite the warnings to the industry since they were desperate for short-term gains.

Consequently, it led to a fully exploited cod stock, resulting in around 40,000 people losing their livelihood with an ecosystem in complete ruin causing a major economic impact for the area.

According to a report released by the New Economics Foundation (NEF) in the United Kingdom, overfishing costs more than 100,000 jobs and up to $3.2 billion annually since the dwindling fish stocks are losing its ability to provide any sustenance.

Another major sector economically impacted due to overfishing is the tourism industry. Charter boat companies are finding it difficult to stay profitable since many tourists are now unwilling to pay high fees for ordinary & dull recreational ocean tours.

Leatherback turtles predate on jellyfish and can consume 600 or more jellyfish in a single day. When the turtle population declines due to bycatch, the jellyfish population grows which makes certain recreational zones dangerous, negatively affecting revenues coming from tourism.

Bottom trawling as we discussed earlier is also wreaking havoc on the seabed that affects seagrasses, interdependent coral reefs & its vibrant fish species with aesthetic value, and other seafloor habitats which have great value for tourism.

10) Collapse of the World’s Largest Ecosystem and a Lost Sensation of a Rich Ocean

Considering all the outcomes discussed above due to overfishing, we learned the devastating impact it can have on the largest ecosystems in the world.

Given that the ocean covers 70% of the earth’s surface with approx. 2.2 million ocean species and 80% of this enormous undersea realm being unexplored, we may yet to see the full scale of the ripple effect of overfishing.

A report by the New Economics Foundation (NEF) in the UK stated, “overfishing is the single most destructive force in the marine environment.”

Imagine an ocean without intelligent dolphins, magnificent blue whales (we’re really fortunate to be alive to witness the largest animal to have ever existed), schooling fish or amazing coral reefs.

As hypothetical as it may sound, a doomed ocean may not be far-fetched as you may imagine at the current rates of overfishing.

National Geographic reported that “a study of catch data published in 2006 in the journal Science grimly predicted that if fishing rates continue apace, all the world’s fisheries will have collapsed by the year 2048.”

Conclusion

Now that you’re aware of the damage caused by overfishing and how modern & large-scale fishery is on course of disrupting the delicate balance of the ocean ecosystem which can create chain reactions to a point of no return, it’s quite difficult to find an acceptable justification for the crisis at hand. 

While our marine conservation organizations should continue to lobby for creating & imposing better environmental laws, policies and raise public awareness, we all can do our best, making changes at an individual level.

Did you know a vegan diet doesn’t contribute towards overfishing and has the least environmental impact?

Read more to know how a vegan diet reduces the environmental impact enabling long-term sustenance, besides enjoying its many health benefits, and reducing demand for products derived from animals!    

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• Documentaries on Environment & Species Extinction
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• Environmental Impact of Vegan Fashion

Other Links:

• Home (2009 film – YouTube)
• Oceanography Guide for Kids with Fun Activities and Facts

References:

https://www.worldwildlife.org/threats/overfishing

https://www.worldwildlife.org/publications/living-blue-planet-report-2015

https://www.iucnredlist.org

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5547646/

http://copa.acguanacaste.ac.cr:8080/bitstream/handle/11606/234/Sobrepesca-pdf.pdf

https://news.mongabay.com/2015/01/oceans-15-meet-the-species-that-have-vanished-forever-from-our-seas/

http://www.fao.org/fishery/sofia/en

http://www.fao.org/3/i9540en/I9540EN.pdf

https://ocean.si.edu/ocean-life/sharks-rays/shark-finning-sharks-turned-prey

http://ec.europa.eu/environment/integration/research/newsalert/pdf/could_freshwater_crustaceans_curb_algal_blooms_462na4_en.pdf

https://www.fishforward.eu/sl/facts-figures/

https://oceana.org/sites/default/files/reports/Bycatch_Report_FINAL.pdf

https://www.fisheries.noaa.gov/species/sei-whale

http://www.fao.org/state-of-fisheries-aquaculture/en/

https://energyefficiency-fisheries.jrc.ec.europa.eu/c/document_library/get_file

https://www.cdc.gov/habs/illness-symptoms-marine.html

https://oceanservice.noaa.gov/facts/ocean-species.html

https://oceana.org/sites/default/files/reports/SOWF_FINAL_July071.pdf