The Environmental Impact of Fishing and Climate Change | Shellethics


In as little as 32 years time, researchers estimate that the world’s oceans will be empty of fish due to the decimation of species from overfishing, pollution, habitat loss, and the impacts of climate change. The environmental impact of fishing at a global scale now sees fish levels so heavily exploited or entirely depleted that without an urgent halt on treating the ocean and its inhabitants like an inexhaustible supply of inanimate food products, we may be the last generation of people to experience the incredible ocean life and benefit from the critical ecosystems supplying a large portion of our oxygen.

The Census of Marine Life is the first of its kind—a 10-year international effort undertaken in to assess the diversity, distribution, and abundance of marine life—estimates that there are more than 230,000 different species in the ocean. The 2010 results showed that around a fifth of the world’s marine species are crustaceans such as lobsters, crabs, krill, and barnacles. When you include molluscs and fish, including sharks, they account for about half of the species that exist in the ocean. The marketable species regularly used in conservation campaigning—whales, sea lions, turtles and sea birds—account for less than 2% of the species in the world’s oceans.

These surveys also highlighted major areas of concern for marine conservationists in regards to the environmental impact of fishing and climate change. In each region, there is the same story of a major collapse of what were usually very abundant species stocks that are now only 5-10% of what they used to be. Human-driven problems of overfishing, degraded habitats, pollution, and the arrival of invasive species play a huge part. But the major problems around the corner are rising water temperatures and ocean acidification because of climate change and the increase in the number of ocean dead zones that are low in oxygen and, therefore, unable to support life at all.

It’s a long table of contents, but there’s a tl;dr summary section at the end.

Table of Contents ▼▲

  1. The Numbers
  2. Fish Stocks
  3. Bycatch
  4. Top Ocean Predators
  5. Destruction
    1. An Empty Ocean 2048 Study
    2. WWF Species Collapse Study
    3. Ocean Pollution
    4. Phytoplankton and Oxygen Depletion
    5. Trawling
    6. Ocean Acidification and Warming
    7. Coral Reefs
    8. The Great Barrier Reef Coral Bleaching
    9. Australian Mangrove and Kelp Forest Deaths
    10. The Galápagos Islands
    11. The North Atlantic Ocean
    12. The Arctic and Antarctic
  6. tl;dr — A Summary

The Environmental Impact of Fishing and Climate Change

The Numbers

While we’re able to account approximately for the number of individual land animal lives forcibly taken every year, it’s a little more difficult quantifying the number of individual marine lives taken. This is because fish are typically measured in the millions of tons rather than per head. New research published this year in Nature Communications shows that while the quantity of fish caught annually did reach a peak in 1996, that peak was much higher than originally thought. Instead of pulling out 86 million tons of fish that year according to the FAO, the industry actually took 130 million tons of fish out of the oceans. Since then, those numbers have gone down, but not by as much as we thought—the 1.2 million decline each year since 1996 has actually only been 0.38 million tons per year.

The average individual eats a staggering 20kg (44 pounds) of fish a year and the overexploitation of the world’s fish supply has tripled since the 1970s.

Food and Agriculture Organisation 2016

The Nature Communications researcher findings go directly against the official records kept by the Food and Agriculture Organisation (FAO) of the United Nations. The FAO keeps track of how many tons of fish are caught each year by asking countries to report the amount of fish caught every year, which they do. But that only accounts for the official catch on commercial boats, not fish caught by illegal fishing operations, or caught for food and not reported to the government, or even the by-catch, unwanted animals and fish that get swept up in commercial nets and are discarded before they make it back to port.

All of those little omissions add up to a gaping hole in the data. So while the FAO data is still absolutely relevant, it’s important to keep in mind that it only includes the official catch on commercial boats and far more lives are lost along the way.

The FAO reported that in 2011, global fish consumption hit a record high of 17kg (37 pounds) per person per year, even though global fish stocks had continued to decline. The State of World Fisheries and Aquaculture 2016 report from the FAO states that the world per capita (average per person) fish supply reached a new record high of 20kg (44 pounds) in 2014, in part because of the vigorous growth in aquaculture, which now provides half of all fish consumed by humans.

The human species violently pulls out of the ocean and kills, at a minimum, 1 trillion fish per year. That’s 1,000,000,000,000 or one thousand million individual fish. At the high end, it’s 2,740,000,000,000 fish who die every year.

Fish Count

To put a figure on just how many individual lives are taken from the ocean each year, Fish Count have instead based their research on the fisheries capture tonnage statistics published by the FAO and the estimates of mean weights for different species. Their results host the most reliable estimate of fish numbers caught per year which sits between 0.97 – 2.74 trillion individual lives. An estimate that does not include bycatch, fish caught in unrecorded captures, or fish that escape from fishing gear but are fatally stressed or injured in the process.

Fish Stocks

An analysis published in 2015 in the PNAS finds that the ability of fish populations to reproduce and replenish themselves is declining across the globe. The researchers looked at data from a global database of 262 commercial fish stocks in dozens of large marine ecosystems across the globe. Identified was a pattern of decline in juvenile fish—young fish that have not reached reproductive age—that is closely tied to a decline in the amount of phytoplankton in the water.


Gregory L. Britten,lead author, University of California

When fish are young, their primary food is phytoplankton and microscopic animals and if they don’t find food in a matter of days, they can die. The researchers looked at plankton and fish reproduction declines in individual ecosystems and when the numbers were averaged, there was a decline globally. The decline in phytoplankton was a factor in all species and it was a consistent variable in the study. It’s also directly linked to climate change: Change in ocean temperature affects the phytoplankton population, which is impacting fish stocks.

Another pervasive human-created problem directly affecting phytoplankton is the ingestion of microplastics from mass ocean plastic pollution

The-Environmnetal-Impact-of-FishingDeclining Fish Stock In Most Of The World’s Marine Ecosystems. Percent change in the ability of fish stocks to produce surviving offspring (per decade, relative to the historical maximum of productivity). Source: Gregory L. Britten/Dalhousie University and Proceedings of the National Academy of Sciences.

A 2012 study published in SpringerLink by the Fisheries Centre at the University of British Columbia concurs with a recent assessment-based analysis by FAO. It shows that the environmental impact of fishing is affecting fish stocks across the globe where there are increasing trends in the percentage of overexploited, depleted, and recovering fish stocks. While there is decreasing trends in underexploited and moderately exploited fish stocks. Both give cause for grave concern.

However, the Fisheries Centre study shows far more alarming slopes in the numbers. This study has been summarised into a handy video by The Economist.


It is little wonder fish populations are being exploited and depleted at such alarming rates when you consider almost 3 trillion fish are pulled out of the ocean every single year. This mind-boggling number doesn’t even include those who are labelled as “bycatch”—the term for dead or dying non-target fish and ocean wildlife who are brought to port and who are discarded at sea—where according to environmental activist group Oceana’s 2014 study, some estimates of global bycatch may amount to 40% of the world’s catch.

The environmental impact of fishing is sometimes indiscriminate. Scientists estimate that as many as 650,000 whales, dolphins, and seals were killed around the world each year throughout the 1990s as a result of bycatch. There’s little time for recovery and breeding to replenish population numbers before another round of death nets approach. Fish trawling, whether it’s bottom trawlers or mid-water trawlers, are very large producers of bycatch because they are highly indiscriminate and capture any and all species in their path.

Hundreds of thousands of dolphins, whales, sharks, sea birds, sea turtles, and fish needlessly die each year as a result of indiscriminate fishing gear.

Amanda Keledjian, report author and Oceana marine scientist

Top Ocean Predators

Whales, like all other marine life, must contend with a variety of threats while still trying to recover from a century of commercial whaling that took many species to the brink of extinction. These threats include habitat loss and degradation, pollution, ship strike, underwater disturbances from ships, oil and gas operations, and military exercises, oil and gas drilling/extraction, entanglement in fishing gear, and the growing impacts of climate change.

Back in 1986, the International Whaling Commission (IWC) enacted a moratorium on all commercial whaling. Since then, three nations—Iceland, Norway, and Japan—have brutally slaughtered over 25,000 whales under the guise of scientific research and for commercial purposes. Seemingly, the IWC does not have the capacity to enforce their own moratorium. Sea Shepherd, however, guided by the United Nations World Charter for Nature, is the only organisation whose mission is to enforce these international conservation regulations on the high seas.

Marine inhabitants all live their lives for their own reasons, but they also are all part of one giant food chain supporting one another’s existence. While whales are at the top of this food chain given their size and predatory status, they play a critical role in the overall health of the marine environment itself. Whale excrement is responsible for fertilising phytoplankton who produce upwards of 70% of the world’s oxygen So the fewer whales there are, the less phytoplankton there is. The less phytoplankton there is, the less zooplankton and fish there are, and the less carbon dioxide sequestering and oxygen production that is able to occur.

At the large end, whales are as critically important to the marine and land ecosystems as the tiny phytoplankton are. Without them, the oceans die. And when the oceans die, we die.

Unfortunately, the large size of whales does not protect them; 7 out of the 13 great whale species are classified as endangered or vulnerable, even after decades of protection, according to the WWF

The exorbitant fishing industry also now threatens to drive a third of the world’s open-ocean shark species to extinction, where hammerheads, giant devil rays, and porbeagle sharks are among 64 species on the first ever red list for oceanic sharks produced by the International Union for Conservation of Nature (IUCN).

Sharks have shaped marine life in the oceans for over 450 million years and are essential to the health of our oceans, and ultimately to the survival of humankind. Sharks, as apex predators of the oceans, keep other marine life in healthy balance and regulate the oceans. Sharks and their relatives include some of the latest maturing and slowest reproducing of all vertebrates and they exhibit the longest gestation periods.

A globalised trade of shark fishing meets the Asian demand for shark fin soup, a traditional and usually expensive Chinese dish. The lucrative trade in fins remains largely unregulated across the 86 countries and territories. The environmental impact of fishing for sharks has unpredictable consequences for ecosystems as the decrease of sharks can lead to increases or declines in other species.

The human species has managed to outdo the top predators of the ocean—like the great white shark or killer whale—by placing itself in a position of pure uncaring aggression and dominance through a relentless hunt of net and boat that instigates an enormous magnitude of suffering to trillions of animals every single year, threatening ecosystems around the globe.

The top marine predator is no longer the great white shark or the killer whale, it’s us.


An Empty Ocean 2048 Study

A study by an international team of ecologists and economists has made an incredibly scary prediction: In approximately 32 years time, the world’s oceans will empty of fish, which when it occurs, would effectively end life as we know it on planet Earth.

Some might think this is alarmist, but the study is backed up with good ol’ scientific fact. The 2006 study included 32 thorough experiments on a variety of marine environments, and the team of researchers looked at the history from the past 1,000 years in 12 different coastal regions around the world. Then they analysed fishery data from 64 marine ecosystems and how nearly 50 protected ocean areas recovered after their protection. The results are terrifying.

Overfishing, habitat loss, climate change, and pollution are driving numbers of most species into a faster and faster decline. Only 1% of the ocean was deemed protected when the study was released. As of 2014, the World Database on Protected Areas—run by the United Nations Environment Program—reported that only 2.8% of the ocean is protected, and much of that is only token protection that isn’t effectively enforced. The environmental impact of fishing and climate change are literally emptying out the ocean fish by fish.

This isn’t predicted to happen. This is happening now.

Nicola Beaumont, a PhD of the Plymouth Marine Laboratory, UK

Every species in the ocean plays a critically vital role in the marine ecosystem where balance is key for everything to remain in sync. Humans are nothing but the the proverbial brick in the washing machine. The benefits that human life receives from the marine ecosystem existing are the filtering of toxins from the ocean, controlling of algae blooms, which if left uncontrolled by nature, can have disastrous effects, the sequestering of carbon dioxide, and the production of oxygen.


Boris Worm, study author, PhD from Dalhousie University in Halifax, Nova Scotia

WWF Species Collapse Study

According to the Living Blue Planet Report, released in 2015 by the World Wildlife Fund (WWF) in collaboration with the Zoological Society of London, the Living Planet Index (LPI) measured the trends in 10,380 populations of 3,038 vertebrate species, and has shown a shocking decline of 52% between 1970 and 2010.

In other words, as humanity continues to make unsustainable demands on nature population sizes of mammals, birds, reptiles, amphibians, and fish have fallen by half on average in just 40 years. Around one in four species of sharks, rays and skates is now threatened with extinction, due primarily to overfishing. Sharks and their relatives include some of the latest maturing and slowest reproducing of all vertebrates.

More fish are being caught at greater depths than ever before. Around 40% of the world’s fishing grounds are now in waters deeper than 200m and many deep-water species are likely to be overexploited. Several decades ago it was virtually impossible to fish deeper than 500m. Now, with technological improvements in vessels and gear, the environmental impact of fishing trawls is felt at depths of up to 2,000m. At this depth, rapid declines in populations occur who are low in productivity, with long life spans, slow growth, and late maturity.

In the last 200 years, the ocean has absorbed around a third of the CO2 produced by human activities and has absorbed over 90% of the extra heat trapped by the rising concentrations of atmospheric greenhouse gases. By absorbing CO2, the ocean is becoming more acidic—now occurring at a rate that is faster than any other period in the past 65 million years.

Warming and acidifying oceans amplify the impact of other pressures from overfishing, habitat destruction, and pollution. Acidification is expected to impact ocean species to varying degrees. It is thought that photosynthetic algae and seagrasses may benefit from higher CO2 levels, but algae blooms are lethal to fish. Corals are particularly sensitive to ocean acidification because acidified seawater tends to slow skeletal growth.

Importantly, a 2013 comprehensive meta-analysis of 228 studies examined the biological responses to ocean acidification. When researchers pooled marine organisms together, in response to ocean acidification they found a decrease in survival, calcification, growth, development, and abundance. While the magnitude of these responses varied among different groups, the overall conclusion is one of problematic sensitivity.


Captain Paul Watson, Sea Shepherd

The WWF acknowledges that the fisheries sector is often a buffer for populations marginalised by conflicts, climate events, poverty or unemployment, which makes it politically difficult to restrain access to resources, placing vulnerable populations in even more precarious situations. However, for a vast majority of people across the globe food availability, especially plant-based foods that are more resource efficient, are not scarce. Addressing the drivers of overfishing throughout the vast majority of coastal waters and the high seas remains an urgent challenge.

Ocean Pollution

Ocean dead zones are ocean habitats that would normally be teeming with life but essentially become biological deserts void of oxygen. Marine life suffocate and die or they leave the area entirely. These lifeless areas can occur naturally at smaller levels, but primarily they occur near areas where there is heavy agricultural and industrial activity. Runoff from land, sewage, agriculture fertiliser, pesticide, and manure are piped as wastewater into the network of rivers and streams, which eventually hit the ocean coasts.

These excess nutrients compromise its quality accordingly. There are over 550 ocean dead zones as at 2014, and a study from the University of California showed that some sea floors have taken more than 1,000 years to recover from past eras of low oxygen.

Phytoplankton are attracted and appear in mass numbers around these nutrient dense areas. One might think that the more phytoplankton the better because of their ability to sequester carbon dioxide from the Earth’s atmosphere and produce oxygen, but this is not actually the case. We definitely need phytoplankton in the ocean for the world’s oxygen supply, but they need to be evenly distributed. The excess nutrients fertilise the rapid growth of the phytoplankton in a process known as eutrophication. When the phytoplankton use up all the nutrients, they die and sink to the bottom as organic matter, where they are decomposed by bacteria. This kind of massive algae bloom is then consumed by microbes that also consume oxygen in the process.

Upwards of 70% of the world’s oxygen is produced via phytoplankton while the rest is produced by photosynthesis on land by trees and other plants. Algae blooms and ocean dead zones are a direct threat to phytoplankton and the world’s supply of oxygen.

Currently, one of the largest ocean dead zones forms in the Gulf of Mexico every spring—2002 saw the largest dead zone ever recorded at 21,965 square kilometres (8,481 square miles). This dead zone off the Louisiana coast is the second largest human-caused coastal hypoxic area in the global ocean and stretches from the mouth of the Mississippi River into Texas waters and less often, but increasingly more frequent, east of the Mississippi River. As farmers across half of the United States fertilise their lands preparing for crop season, much of which goes directly to the mouths of farmed animals, it runs off of agricultural fields in water and into streams and rivers, and eventually into the Gulf of Mexico.


Noise Pollution — Navy Sonar Systems

While the use of sonar by the US Navy is not an act of fishing per se, it is an act of abuse and disruption against marine life and does impact the ecosystems that these animals support by simply going about their lives. It is another prime example of the disregard humans have had for the ocean and its inhabitants.

In response to threats from the Soviet Union submarines, the US Navy developed a special long-range sonar tool called the Surveillance Towed Array Sensor System Low Frequency Active (SURTASS/LFA). The massive reel hosts 18 aquatic subwoofers that emit low frequency tones between 100-500 Hz and this same range is used by whales, dolphins, and porpoises use sound to find food, meet mates, avoid predators, maintain social groups, or to navigate the wide seas. For them, listening in the ocean is as important as seeing is for humans.

The SURTASS/LFA sounds like a threat to these animals and they react accordingly, and in extreme cases this means death. Research has increasingly shown that noise pollution has devastating impact upon marine mammals. Low-frequency sonar has been implicated in mass whale and dolphin beachings. A 2013 study showed that the blue whale abandoned feeding and swam rapidly away from sonar noise. During Navy war games in 2014, seven Cuvier’s beaked whales were standing along the coast of Crete, Greece—similar to several prior incidents going back two decades where all signs point to navy activity. Mass strandings of multiple whale and dolphin species soared since the 1950s. In 2008, the UK had its largest ever mass stranding event of twenty-six short-beaked dolphins in Falmouth Bay, Cornwall, where the navy was found to be the most probable cause of the deaths.


Sarah Dolman, Whale and Dolphin Conservation

Beaked whales are the most common species affected by mass strandings likely because of their shy nature, which makes them more easily scared by noises that they may interpret as killer whale sounds. Autopsies showed that the whales had gas bubbles in their tissues, leading some to hypothesise that sonar may cause decompression sickness in cetaceans.

Thankfully, the US Navy’s attempt to convince the courts for the last 10 years that their sonar is safe for marine life has come to an end. On July 15 2016, the Ninth US Circuit Court of Appeals in San Francisco said that nope, it’s not safe at all. The Navy will be barred from using its deep submarine hunting sonar in much of the world’s oceans during peacetime.

A beached whale

Phytoplankton and Oxygen Depletion

With each species of fish existing within a complex ecosystem and top-to-bottom style food chain, the impact of the exploited and depleted species by human activity on other marine species is becoming apparent. The marine environment is being thrown completely out of kilter.

One example of how large of an impact climate change and overfishing has on the marine world is the often unknown partnership between whales, phytoplankton, and the existence of all oxygen-dependent lifeforms. The Plankton family consists of bacterioplankton (bacteria), virioplankton (viruses), phytoplankton (plants), and zooplankton (animals). Phytoplankton provide the primary food source for the zooplankton and together, they form the base of the oceanic food chain. Much larger zooplankton, fish, and mammals all depend on these plankton for their survival. The bacterioplankton recycle and re-mineralise materials and energy within the marine food chain.

Phytoplankton also play a critical role in sequestering carbon dioxide from the Earth’s atmosphere and releasing oxygen into the water, which is part of the process photosynthesis. These one-celled plants use energy from the sun to convert carbon dioxide and nutrients into complex organic compounds, which form new plant material. This process—photosynthesis—is how phytoplankton grow. Upwards of 70% of the world’s oxygen is produced via phytoplankton photosynthesis, while the rest is produced by photosynthesis on land by trees and other plants. Phytoplankton and the ocean are therefore considered one of the biggest carbon sinks on the planet. In fact, 26% of all the carbon released as CO2 from fossil fuel burning was absorbed by the oceans.

During 2015, researchers from the University of Leicester have revealed that Earth’s oxygen could dramatically fall due to change in ocean temperature of just several degrees. The study has shown that an increase in the water temperature of the world’s oceans of around 6°C—which some scientists predict could occur as soon as 2100—could stop oxygen production by phytoplankton by disrupting the process of photosynthesis. Understandably, ocean dead zones also compound this threat and are a critical problem to the survival of phytoplankton.


Professor Petrovskii, University of Leicester

The results indicate that the depletion of atmospheric oxygen on global scale, which if it happens can kill most of life on Earth and is a global ecological disaster that has been overlooked. One of the most notorious and popular topics of climate change is the threat of global flooding that will result from the melting Antarctic ice if the warming exceeds a few degrees compared to the pre-industrial level. However, it is quite clear that this is now not the biggest danger. The very real threat of oxygen levels dropping as the ocean dies will be catastrophic to life on Earth.

If the ocean dies, we all die.

Captain Paul Watson, Sea Shepherd

Phytoplankton bloom off Iceland.


By the end of the 20th Century, the deep sea was finally recognised as the largest environment on Earth containing numerous sub-habitats with unique abiotic and biological characteristics, and supporting a particularly high level of biodiversity. It’s the ocean waters that are deeper than 200m which form the largest environment on Earth with an enormous volume (1368×10 km) covering an area of 360 million km—equivalent to about 50% of the surface of the Earth, and have an average depth of 3800m, with a maximum depth of 10,924m in the Mariana Trench.

For a long time it was virtually impossible to fish deeper than 500m. Now, with technological gains in vessels and fishing gear, trawling is occurring at depths of up to 2,000m. Of course, what drove the development of trawling in the 1960s was the fact that industrial fisheries caused the steep decline of shallow coastal water resources and the destruction of marine habitats in the last 50 years. To keep the industry afloat, they needed to quickly move deeper into the ocean.

Trawling represents one of the most common fishing practices along the coastal oceans of the world.

Trawls are bulldozers of the ocean that scoop up and destroy anything in their path. Trawls are enormous, cone-shaped nets that are towed by one or two boats. As the net is towed, it herds and captures thousands of fish and other sea creatures. The net is wide at the mouth and then narrows to a bag, where the fish are trapped and crushed as they are dragged along and eventually pulled to the surface where they die.

Trawl fishing can take place in shallow to extremely deep depths. Bottom trawls are when the net is towed along the bottom of the ocean floor, and mid-water trawls are towed off the bottom. The spread of the trawl net can be up to 100 meters wide and 12 meters high, or a net as wide as a football field and higher than a three-story house.

Bottom trawling turns physically diverse environments, teeming with life into barren deserts. Essentially, it is equivalent to clear-cutting the rainforest, especially when trawling over coral reefs.

The Safina Center (formerly Blue Ocean Institute)

Trawls are highly indiscriminate, capturing any and all species in their path and play a massive role in the hugely problematic issue of bycatch. Shrimp trawls in particular catch very high amounts of bycatch—often 2-10 times the amount of shrimp caught. Now, in the US, many shrimp trawlers are required to install turtle excluder devices and/or bycatch reduction devices in their nets. This is appears difficult to enforce however and is certainly no guarantee at saving lives of certain marine animals.

Studies show that bottom trawling long continental slopes has a major impact on deep-sea sedimentary ecosystems, causing their degradation, driving a lack of variety in species (infaunal depauperation), and a collapse of biodiversity and ecosystem functions at the lowest ecological regions at the depths of the ocean. A 2014 study showed the Mediterranean Sea now has up to a 52% loss in organic matter, a 37% lower organic carbon turnover, with a whopping 80% reduced meiofauna abundance, and a 50% loss of biodiversity. A study in PNAS showed that trawling on deep-sea muddy bottoms strongly alters the biochemical nature of the sediment and reduces the species diversity and abundance of meiofaunal organisms.

The environmental impact of fishing, and trawling specifically, is destructive. It is responsible for slaughtering marine life to the tune of trillions of lives each year.

Pierre Gleizes

Ocean Acidification and Warming

The ocean is absorbing upwards of one-quarter of the human generated carbon dioxide (CO2) from the atmosphere at an unprecedented rate and the resulting acidification is transforming marine ecosystems. Initially, it was thought that the ocean absorbing carbon dioxide might be a good thing because it leaves less carbon dioxide in the air to warm the planet shielding us from the worst effects of global warming. However, it’s become clear that this slowed warming has come at the cost of changing the ocean’s chemistry.

Atmospheric CO2 concentrations have increased from a pre-industrial level of approximately 280 ppm to approximately 385 ppm, and there is further increases of 700–1000 ppm anticipated by the end of the 21st century. The change over the last three decades in CO2 has resulted in a global average temperature increase with much of the additional energy absorbed by the world’s oceans causing a 0.8°C rise in sea surface temperature over the past century. This sounds like a small number, but small numbers result in big impacts. The rapid uptake of heat energy and CO2 by the ocean results in a series of associated changes in seawater chemistry, including reductions in pH levels, carbonate saturation state, and increases in dissolved CO2 and bicarbonate ions—the phenomenon known as ocean acidification.

Ocean warming, ocean acidification, and deoxygenation—enhanced in parts because of coastal hypoxic dead zones—are the three prime effects of climate change on the ocean and are described as the “deadly trio“. The addition of anthropogenic pollution and fish exploitation to the deadly trio have created a unique set of stressors for the vast ocean to try and cope with. And it’s not doing very well.

A 2013 report by the International Programme on the State of the Ocean (IPSO) and the International Union for the Conservation of Nature (IUCN) shows that the ocean is becoming more and more acidic at the fastest rate in 300 million years, due to human-generated carbon dioxide emissions from burning fossil fuels. The report also states that anthropogenic stressors interact in a synergistic manner, which means that the combination of two or more stressors magnifies the sum of each one occurring alone.



There are changes occurring across all ocean regions and in some cases, there are entire ecosystem collapses where physical and biological structures are simplified down with such significant biodiversity loss. Acidification harms marine creatures that rely on calcium carbonate to build coral reefs and shells, as well as plankton, and the fish that rely on them. Phytoplankton are responsible for producing upwards of 70% of the world’s oxygen. A 2013 comprehensive meta-analysis of 228 studies examined the biological responses to ocean acidification. When researchers pooled marine organisms together, in response to ocean acidification they found a decrease in survival, calcification, growth, development, and abundance. While the magnitude of these responses varied among different groups, the overall conclusion is one of problematic sensitivity.

The IPCC have made it clear: the ocean is taking the brunt of warming in the climate system. The impacts of continued warming is projected to have in the decades leading up to 2050 include:

  • Acidification: Current levels of CO2 release continued will drive extremely serious consequences for ocean life. The projected CO2 concentrations of 450-500 ppm in 2030-2050 will will exceed calcification in the coral reef building process, resulting in the extinction of some species and decline in biodiversity overall,
  • De-oxygenation: The oxygen inventory of the ocean is progressively declining and predicted is a decline of between 1% and 7% by 2100,
  • Warming: Reduced seasonal ice zones, including the disappearance of Arctic summer sea ice by ca. 2037; an increased stratification of ocean layers, leading to oxygen depletion; an increased venting of the greenhouse gas methane from the Arctic seabed; and an increased incidence of hypoxic algae bloom events.
  • The Deadly Trio: Acidification, warming, and deoxygenation of the ocean will have cascading consequences for marine biology, including altered food web dynamics and the expansion of pathogens.
Ocean Acidification Saturation
Projections by 2100.

Coral Reefs

Coral reefs provide some of the most biologically rich, productive and economically valuable ecosystems on Earth. Over 25% of all marine species live in coral reefs, and yet they cover less than 0.1% of the ocean or an area about half the size of France.

During 2015, the WWF reported that three-quarters of the world’s coral reefs are currently threatened. This is because of pressures like increased fishing, poor water quality as a result of runoff from agriculture (animal agriculture especially with fertilisers, pesticides, and manure), deforestation (primarily for agriculture pasture and feed crops), coastal development and shipping, as well as rising ocean temperatures and acidity brought on by climate change that contribute to coral bleaching events.

As climate change worsens and the current rates of temperature continue to rise, the ocean will become too warm for coral reefs by 2050, which would mean a major disruption to at least 25% of the biodiversity in the ocean.

Of the 930 fish species in WWF’s Living Planet Index (LPI) database, 352 are classified as “reef associated” (living and feeding on or near coral reefs), and comprise of 2,501 populations. The index for reef-associated fish species declined startling 34% between 1979 and 2010.

Corals are suffering from poor water quality due to deforestation and coastal agriculture, along with increasing fishing pressure on beneficial animals that help them stay healthy, such as reef fish.

Mr Ack, WWF Senior Vice President for Oceans

The Georgia Institute of Technology study by their School of Biology in 2010 showed that over the last 30-40 years, coral cover in the Caribbean has declined by 80% and in the Indo-Pacific by 50%. They found that bleaching is just one part of the problem—coral diseases have also increased dramatically, often in association with increased temperatures and coral bleaching. As coral reefs decline, they become dominated by seaweeds, which creates negative feedback that reinforces seaweed-dominance and produces a coral ‘death spiral’. It then gets worse. Once seaweed biomass becomes so prolific, the coral reef deaths result in a decline in herbivorous fishes because there are no longer any physical structure and habitat complexity upon which fishes and other reef species depend.

Even seagrass coverage worldwide has declined by about 30% over the last century, and they provide a range of ecosystem services such as catching sediment and stabilising the seabed, providing grazing for dugongs, manatees and green turtles, and act as a critical habitat for important fish species.

The Great Barrier Reef Coral Bleaching

Australia’s Great Barrier Reef is the world’s largest single structure made by living organisms that can actually be seen from space. It comprises of 2,900 individual reefs over an area of approximately 344,400 square kilometres. Over the past 30 years, the Great Barrier Reef has lost more than half of its coral cover. More than 40% of coral loss has been caused by outbreaks of the coral-eating crown-of-thorns starfish, which are fuelled by nutrient run-off from agriculture pouring into the ocean.

During April 2016, the Great Barrier Reef was smashed with its 8th devastating coral bleaching event affecting 93% of its reefs. Mass coral bleaching occurs because of heightened sea temperatures due to climate change from burning fossil fuels and animal agriculture and then the El Niño, which cause the coral’s primary supply of energy—a tiny photosynthetic algae called zooxanthellae—to die off.

The current, ongoing mass bleaching event is the worst in the Great Barrier Reef’s history.

Climate Council’s 2016 Report

Fast forward to July and Justin Marshall, from the University of Queensland and the chief investigator of citizen science program Coral Watch, spent a week conducting surveys on the reefs around Lizard Island. Marshall’s findings were devastating and he has described a “complete ecosystem collapse .. on parts of the Great Barrier Reef, as fish numbers tumble and surviving corals continue to bleach into winter.”

Many people blame the El Niño—a temporary change in the aberrations of ocean currents and weather systems that start in the waters of the tropical Pacific and send shock waves around the world—and position this event as unavoidable. However, the mass bleaching event was driven by climate change from human activities around burning fossil fuels and animal agriculture, which raised water temperatures close to the maximum threshold that the corals could stand. The El Niño was simply the tipping point—an event that the Great Barrier Reef could have withstood if it weren’t for the impacts of climate change from human activity.

All mentions of Australia were removed from the final version of a Unesco report on climate change and world heritage sites after the Australian government objected on the grounds it could impact on tourism.The Guardian managed to obtain a draft chapter for a Unesco report on the Great Barrier Reef warned that it was ‘poor and deteriorating’ and ‘assailed by multiple threats’ but the Australian government made sure it wasn’t released in the final copy.

The conservative and laughable Australian government is known for climate change denial with a string of party leaders who refuse to acknowledge the mounting scientific evidence. The crackdown on the Unesco report is another example of their morally bankrupt behaviour.

Australian Mangrove and Kelp Forest Deaths

Coinciding with the world’s worst global coral bleaching event, climate change and El Niño have created further destruction during July this year where the worst mangrove die-off in recorded history has occurred stretching along 700km of Australia’s Gulf of Carpentaria. Norm Duke, an expert in mangrove ecology from James Cook University, calculated that the dead mangroves now cover a combined area of 7,000 hectares.

Mangroves play an essential role in a region’s ecosystem where they behave somewhat like kidneys, filtering and purifying water. As water from rivers and floodplains runs into the ocean, mangroves filter a lot of sediment, and protect coral reefs and seagrass meadows. That critical service would be lost in the areas affected by die-off. They also host as nurseries for many fish species.


Norm Duke, James Cook University

Kelp forests on Australia’s west coast have been devastated by marine heat waves in the last few years. The Great Southern Reef is a system of rocky reefs covered by kelp forests that runs for 2,300km along the south coast of Australia, extending past Sydney on the east coast, down to Tasmania and, previously, back up to Kalbarri on the west coast.

A study published in July of this year has shown that during 2011 and 2013, about 90% of the kelp forests that make up the north-western tip of the Great Southern Reef disappeared over the period. This 100km of kelp forest died because of the marine heatwave in 2011, which saw the ocean temperature increase by 2C. This caused an influx of seaweed turfs, corals, and coral fish usually found in tropical and subtropical waters to be pushed down south from the north.

This rich area supports most of the nation’s fisheries, including the lucrative rock lobster and abalone fisheries. It is also a global biodiversity hotspot with up to 30% of species endemic and is worth about $10 billion to the Australian economy.

The Guardian

The Galápagos Islands

The Galápagos Islands are approximately 1,000km from the South American continent. The 19 islands are often described as a unique ‘living museum and showcase of evolution’: the convergence of three different ocean currents, its isolation, and the on-going seismic and volcanic activity created somewhat of a melting pot of unusual marine species—some found no where else in the world. Charles Darwin visited the Galápagos Islands in 1835 and his theory of evolution was inspired here.

The Galápagos isolation, however, was until an accidental human arrival in 1535. Fast forward and the 70,000 square km of ocean surrounding the UNESCO World Heritage Site islands is now a marine reserve (second in size only to the Great Barrier Reef), But concerningly, one of the most fragile environments on earth is now one of the fastest-growing economies in South America, is home to 40,000 people, sees more than 145,000 tourists per year, and with them have come hundreds of damaging introduced species, invasive plants, waste, pollution, and an infrastructure that simply can’t cope.

It’s unsustainable. There’s constantly more, more, more. More flights, more hotels, more cars. It’s uncontrolled. We talk about ecotourism but in reality it’s already showing signs of being mass tourism. People aren’t even coming for the wildlife any more. They just come for a vacation.

Felipe Cruz, Charles Darwin Foundation

Although the 1998 Galápagos Special Law sought to limit fishing in the marine reserve, the enforcement of the law is weak. Overfishing has become a major threat. Almost all of the Galápagos commercially important coastal species are overfished, and the status of offshore species is largely unknown. Sea cucumber populations declined 98% between 1993, when the first legal fishery opened, and 2004. They play a vital role in the ecosystem, regulating water quality, turning over sediment, recycling nutrients, and as prey for commercial species such as crustaceans. Some areas without sea cucumbers have become uninhabitable for other organisms.

The giant tortoises of the Galápagos have become greatly reduced since the discovery of the islands, with populations declining from an estimated 250,000 to between 8,000 – 14,000 in the 1970s.

At the beginning, it was pirates, whalers, seal hunters, and settlers who killed everything in sight with little regard. As recently as World War II, the establishment of an American airbase paired with the predation by dogs and cats and competition by feral goats, saw the iguanas disappear on the Baltra Island. The mass killing of the descendants of domestic animals and pets is on-going, where goats, dogs, cats, and rats are being wiped under conservation out through no fault of their own.

Meanwhile, growing numbers of colonists push to build more roads, clear more land for agriculture, and otherwise humanise the once rich and uniquely special land. Climate change temperature increase estimates will see the Galápagos Islands, which is located at the Equator and surrounded by ocean, warm by at least the global average of 2°C, alongside increasing ocean surface temperatures, ocean acidification, and sea level rise will all negatively affect the Galápagos environment and its non-human inhabitants.

Selfish human activity has been and is the real problem here. The origins of the theory of evolution may have been inspired by the Galápagos Islands, but humankind is altering evolution and simply destroying it.

The Galápagos Islands

The North Atlantic Ocean

The North Atlantic Ocean is one of the world’s richest marine areas hosting diverse inhabitants such as cold-water reefs and hydrothermal vents. The WWF index for deep-sea fish populations for the North Atlantic is based on 77 populations of 25 species, and indicates a 72% decline over the last 40 years. Because of the number of ecosystems in this area—groups of species, communities or habitats that, based on the physical and biological features they possess, are vulnerable to impacts from fishing activities. The environmental impact of fishing, and bottom trawling especially, resulting in overfishing of target stocks damages the marine resources and ecosystems.

One study suggests that the North Sea cod fish stocks are finally improving and could be certified as sustainable within 5 years, according to SeaFish. However, the Marine Conservation Society still regards North Sea cod as a species to avoid because it remains at historically low levels.

There are clear examples of what happens when the human species bases an exploitative industry that requires continual growth but its “product” is finite. We destroy ecosystems and life for blind profit. In the early 1990s, Newfoundland in Canada employed 110,000 people in the fish and fish-processing industry, but the 1992 cod fishery collapsed and 40,000 people lost their jobs, including 10,000 fishermen. The ocean is not an inexhaustible supply of food nor is it a convenient dumping ground.

A 2009 study published in BioScience examined fish who migrate between marine waters (saltwater) and continental watersheds (freshwater) to complete their life cycles within the North Atlantic basin. Data on these 24 species showed that relative abundances had dropped between 90% and 98% of historic levels. The study indicates that the main drivers are habitat loss, overfishing, pollution, nonnative species, aquaculture, and, increasingly, climate change have contributed to these huge declines.

North Atlantic Ocean
Hydrothermal Vents.

The Arctic and Antarctic

With only a sprinkling of 4 million people spread over more than 32 million square kilometres, the Arctic remains largely untouched by direct human impacts. However, the impacts of global climate change are actually faster and more severe in the Arctic than in most of the rest of the world. This is because shiny ice and snow reflect a huge proportion of the sun’s energy back into space, so as the Arctic loses snow and ice, the bare rock and water absorb larger amounts of the sun’s energy. This makes the Arctic even warmer than the rest of the world and is known as the albedo effect.

A 2009 study published in the NOAA has shown that the Arctic summer temperatures today are higher than at any time in the past 2,000 years. As a result, other research shows that Arctic sea ice loss, and the arrival of a nearly ice-free summer, is very likely to occur within the next 30 to 40 years.

It is reasonable to conclude that Arctic sea ice loss is very likely to occur in the first .. half of the 21st century, with a possibility of loss within a decade or two.

2013 study by James E. Overland & Muyin Wang

A guest blog post by Florence Fetterer, principal investigator at the National Snow and Ice Data Center, pieced together the Arctic’s sea ice history back to 1850. It indicated that satellites provide a near-continuous record of Arctic sea ice cover. But this data had to be combined with other sources, which combat for the fact that satellites have only been around for approximately 5o years, and shows that the Arctic sea ice is disappearing at record speed. Fetterer reports that there is no point in the past 150 years where Arctic sea ice extent is as small as it has been in recent years and the rate of sea ice retreat in recent years is also unprecedented in the historical record.

The Arctic is upwards of being 70% marine, and this reduction in sea-ice extent and thickness will radically modify the Arctic’s seascape, with major impacts on atmospheric and ocean circulation, biogeochemical cycles, and ecosystem functioning. Endemic Arctic species, such as the iconic polar bear, are predicted to go extinct in areas currently holding two thirds of the world population by 2050 due to their reliance on sea ice and specialised feeding. The most abundant seabird in the Atlantic Arctic, the little auk, with over 40 million individuals is a specialised diving zooplankton consumer who will have strong sensitivity to environmental change.

Life in the Arctic ocean is reliant on and highly adapted to the presence of ice. On and around the ice, polar bears hunt, seals give birth, walrus rest and feed, and whales feed and hide from predators. But these are just the more visible parts of a whole ecosystem driven by pulses of nutrients mediated by the ebb and flow of sea ice (Eamer et al., 2013). A change in the timing of nutrient pulses can spell difficulty for both endemic and migratory species. Millions of migratory birds rely on the pulse of life in the Arctic spring.

It’s simple: as the climate continues to warm, the Arctic sea ice is disappearing. As each summer passes us by, the amount of remaining ice gets smaller. That summer ice is vitally important to a whole range of animals and local people. One stretch of ice is projected to remain when all other large areas of summer ice are gone—this is the Last Ice Area

The Antarctic has an abundance of animal life. The sea ice serves as the basis for Antarctic ecosystems and most organisms’ life cycles in this region are attuned to ice seasonality. Penguins, whales, seals, albatrosses, other seabirds, and a whole wide range of invertebrates (such as krill) all form part of the Antarctic ecosystem web. The Antarctic is also the coldest place on Earth.


But it seems the harmful reach of human activity can alter even these remote ecosystems. In the past 50 years, the western Antarctic Peninsula region has warmed by over 7°C. Sea ice duration remains in decline by almost 100 days since 1978, which causes a drop in phytoplankton productivity. The barbaric harvesting of great whales, and now krill, has negatively impacted the Antarctic marine ecosystems. A 2010 study found that the density of krill populations has declined 80% since the 1970s due to due to over-harvesting, sea ice loss, and ocean warming and acidification. This is a critically major threat to the survival of many Antarctic species. Krill are also a cold water species and they grow fastest in cold water—any warming can slow down or stop growth.

The foundation of the [Antarctic] ecosystem is melting away.

Hugh Ducklow, biological oceanographer, Columbia University

Adélie penguins are one of four penguin species that breed on the Antarctic continent. They are are ice dependent in a complex way for foraging, resting, moulting, and migrating. 2014 study showed that Adélie penguins are having more trouble feeding as sea ice retreats in areas of the Western Antarctic Peninsula. Another study upsettingly showed that a 500 year old colony in the area went extinct in 2007, and five more colonies have seen an 83% decline in breeding pairs since 1974. Emperor penguins are experiencing similar devastating losses as a result of climate change. A 2001 study found that Emperor penguin populations had declined 50% over the previous 50 years in Terre Adélie.

Data on whale and seal populations is a bit less detailed. A 2012 study did say that “given both this dependence on krill and life histories that exhibit different affinities to sea ice, it is conceivable that Western Antarctic Peninsula marine mammal populations have exhibited trends not too dissimilar from .. penguins.”

The Antarctic receives constant sunlight during summer which spurs the growth of phytoplankton. One of the smallest lifeforms on the planet provides humanity and other life with upwards of 70% of the oxygen supply, and equally important, they support vast swarms of krill and in turn much of the rest of Antarctica’s food web. Remote the Antarctic may be, but the climate changes underway are and will affect animal life who live there, as well as many migratory animals. The ripple effect for marine biodiversity in the ocean is a terrifying thought.

West Antarctic Ice Shelf.

The Ice Sheets in Trouble

The two ice sheets located in Antarctica and Greenland, along with the Arctic sea ice, routinely melt and freeze each year in accordance with the seasons. Several studies now confirm that the west Antarctic ice sheet has begun to collapse due to climate change.

UK researchers complied satellite measurements in 2014 that show that Antarctica is losing 160 billion tonnes of ice per year. This is mainly through thinning of west Antarctica’s ice sheets where mass losses from this area are now 31% greater than over the period of 2005–2010. Another study published in 2014 by NASA shows that the major west Antarctic glaciers have retreated by several kilometres over the past two decades. The University of Washington has found that one of these glaciers (the Thwaites Glacier) is set to collapse over the coming centuries.

These studies arguably show that a complete destabilisation of the west and east Antarctic ice sheets is a very real reality if the warming of the atmosphere and ocean continues. A 2015 study alarmingly warns that the stability of the whole Antarctic continent could be at risk of collapse by 2100. 

The data presented in this study clearly show that climate policy .. over the coming century, have an enormous control over the future fate of surface melting of Antarctic ice shelves.

Dr Karen Frey, study co-author, Clark University, Massachusetts

During 2013 at the IPCC, it was predicted that if our greenhouse gas emissions continue to climb that sea levels could rise by approximately 98cm by 2100. The key drivers behind this rise are obvious: melting glaciers, the amount of ocean water expanding, and the melting of the ice sheet located in Greenland. However, one very large important ice sheet was seemingly overlooked in this study: Antarctica.

When taken into account, the latest research published in Nature from this year shows that global sea level rise could be double IPCC’s initial estimates—sea levels could rise to 2 meters (more than six feet) by 2100. To add further anxiety to the situation, additional new research from NASA this year shows that the melting ice is redistributing water enough to affect changes in the Earth’s axial rotation.

As we witness the sun rise from the east to the west each day, our planet turns from west to east. As it spins around a specific axis with a tilt of about 23.5º, a line can be drawn from the North and South poles. While the poles have actually been shifting over time, which is called “axial wobble”, we’ve known it’s been happening since it was first recorded in 1899. But this new NASA research shows that if as we lose mass from Greenland’s ice sheet, it’s then redistributed elsewhere to different continents, which then causes the spin axis to find a new direction.

Greenland Ice Sheet.

tl;dr — A Summary

If you’re experiencing feelings of too long; didn’t read, then this 30 dot point summary of this entire blog post is for you:

1. It’s estimated that there are over 230,000 different species in the ocean.

2. The average individual human eats a staggering 20 kg or 44 pounds of fish per year.

3. The human species violently pulls out of the ocean and kills between 1 trillion and 2.74 trillion individual fish per year: That’s upwards of 2,740,000,000,000 fish who die every single year.

4. This estimate does not include fish caught in unrecorded captures, or fish that escape from fishing gear but are fatally stressed or injured in the process.

5. The ability of fish populations to reproduce and replenish themselves is declining across the globe.

6. There is an increasing trend in the percentage of overexploited and depleted fish stocks.

7. Some estimates of global bycatch may amount to 40% of the world’s catch.

8. Over 650,000 whales, dolphins, and seals were killed around the world each year throughout the 1990s as a result of bycatch.

9. 7 out of the 13 great whale species are classified as endangered or vulnerable.

10. 64 species of shark species are on the first ever red list for oceanic sharks produced by the International Union for Conservation of Nature (IUCN).

11. A 2006 study showed that in approximately 32 years time the ocean will empty of fish, which when it occurs, would effectively end life as we know it on planet Earth.

12. The WWF Living Blue Planet report shows that between 1970 and 2010, there has been a shocking decline of 52% measured across 10,380 populations of 3,038 vertebrate species in the ocean.

13. There are over 550 ocean dead zones that are biological, deoxygenated deserts void marine life caused primarily because of heavy agricultural and industrial runoff from land, sewage, agriculture fertiliser, pesticide, and manure.

14. The largest ocean dead zone ever recorded in the Gulf of Mexico was in 2002 at 21,965 square kilometres or 8,481 square miles.

15. Low-frequency US Navy sonar has been implicated in mass whale and dolphin beachings for approximately half a century due to the emission of low frequency tones between 100-500 Hz, which is the range used by whales, dolphins, and porpoises.

16. Whale excrement fertilises phytoplankton who are responsible for producing upwards of 70% of the world’s oxygen by the process of photosynthesis.

17. An increase in the ocean water temperature of around 6C could actually stop oxygen production by phytoplankton, and is predicted to occur as soon as 2100.

18. The depletion of atmospheric oxygen on global scale will kill most of life on Earth: When the oceans die, we all die.

19. The ocean waters deeper than 200m form the largest environment on Earth with an enormous volume (1368×106 km3) covering an area of 360 million km2—equivalent to about 50% of the surface of the Earth, and have an average depth of 3800m, with a maximum depth of 10,924m.

20. Since the 1960s, trawling boats represent one of the most common fishing practices along the coastal oceans of the world and scoop up and destroy anything in their path at depths of up to 2,000m.

21. The ocean is absorbing upwards of one-quarter of the human generated carbon dioxide (CO2) from the atmosphere and is changing the ocean’s chemistry in a catastrophically damaging process known as ocean acidification.

22. The three prime effects of climate change on the ocean are ocean warming, acidification, and deoxygenation. They are known as the “deadly trio”.

23. Three-quarters of the world’s coral reefs are currently threatened and the ocean will become too warm for coral reefs to survive by 2050 because of climate change.

24. Australia’s Great Barrier Reef is the world’s largest single structure made by living organisms that can actually be seen from space. During 2016, it was hit with its 8th devastating coral bleaching event affecting 93% of its reefs caused by climate change and the El Niño.

25. Over the last 30 years, the Great Barrier Reef has lost more than half of its coral cover and now parts of it face complete ecosystem collapse.

26. The Galápagos Islands was one of the most isolated and species abundant environments on Earth, but is now one of the fastest-growing economies in South America with much of the unique biodiversity destroyed.

27. The North Atlantic marine populations have suffered a 72% decline over the last 40 years.

28. The Arctic summer temperatures today are higher than at any time in the past 2,000 years, and the arrival of a nearly ice-free summer is very likely to occur within the next 30 to 40 years.

29. The stability of the whole Antarctic continent could be at risk of collapse by 2100.

30. Sea levels could rise to 2 meters or more than 6 feet by 2100, and the water from the redistributed melting ice is enough to affect changes in the Earth’s axial rotation.

Human activity has not just caused the loss of a few fish and some turtles. The environmental impact of fishing is unravelling the fabric of an ecosystem that actually sustains life on Earth. We all live on the Blue Planet together. The human species depends on the vast variety of animals and complex ecosystems far more than they depend on us to live.

In 1972, NASA released the first image of the full sunlit sphere of the Earth. If you’ve ever doubted the primacy of the ocean in shaping the life on Earth, just look at this image. If you’ve ever doubted the link between ocean and climate, this image shows they are inextricably interwoven.

We are all connected.

Error(s) Reported and Edited: Section ‘The Great Barrier Reef Coral Bleaching’: “During April 2016, the Great Barrier Reef was smashed with its 8th devastating coral bleaching event killing affecting 93% of its reefs”.


The Environmental Impact of Fishing and Climate Change | Shellethics
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