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Seven of the Biggest Problems Facing Fish in Our Oceans

Robert Woods has been a fish keeping enthusiast ever since his parents bought him is first tank at age 4. Since then, he has gone on to keep hundreds of different species and now educates aquarists through his online publication Fishkeeping World.


Evidence points to the fact that we are currently facing the Earth’s sixth mass extinction, with extinction rates growing by the day. But why? What are some of the problems that are creating these problems? The oceans are home to many unique organisms, including the largest – the blue whale; and it is home to hundreds  of ecosystems full of vibrant and colorful lifeforms. However it is also used as one of our largest dumping grounds, and extraction of fish and other marine life continues at an unsustainable pace. These, along with other factors, are affecting life in our oceans. Here are seven of the biggest problems which fish are currently facing in our oceans.

Parrotfish, photo courtesy of Robert Woods


Whether it’s for the food industry or the aquarium industry, overfishing is a serious threat to the fish in our sea. There are many species of fish which simply need to remain in the sea, they are not necessary for food security or their lives are not suitable for captivity, yet the Food and Agriculture Organization have estimated that over 50% of species of marine fish have been fully or over-exploited. By overfishing, we are destroying entire ecosystems and the food chains which are essential to keep them thriving. Not only is overfishing wiping entire species out, it’s also having a direct impact on other species in the food web. Some of the methods used for fishing are destructive in themselves, such as bottom trawling which destroys habitats and captures many fish which are not even wanted, and then tossed aside.


Ocean Acidification

The ocean absorbs up to one third of CO2 that we emit worldwide. This helps keep us cooler, but unfortunately makes the ocean more acidic. Over the last 200 years, the concentration of carbon dioxide has considerably risen and during this time, the pH of the surface waters of the ocean has fallen by 0.1pH units. This might not sound like a lot, but it actually equivalent to a 30 percent increase in acidity. The result of this is that carbonate ions are less abundant, and these are an essential building block for sea shells and coral skeletons. This has a direct impact on calcifying organisms such as corals, oysters, sea urchins and clams and  any others. This process is also having an impact on other sea creatures such as pollock as their senses are affected by this change and they can’t detect predators as well.


Ghost Fishing

Ghost fishing occurs when old fishing equipment is lost (or tossed), and continues to catch or entangle fish and other marine life. This can also trigger a chain of injuries or deaths, when smaller animals get caught in abandoned nets, and larger predators in search of their prey find themselves caught in the nets too. Suggestions to prevent ghost fishing includes bio-degradable equipment, as well as schemes which encourage fishermen to recycle gear or other incentives such as buy-back programs.


Commercial Whaling

It’s almost impossible to believe that in our day and age, this is still happening despite wide spread international calls for a total ban on killing whales. Blue whales are listed as endangered on the IUCN list and there is less than one percent of the original population in the Antarctic now. West Pacific grey whales are the most endangered with only a few more than 100 left in the oceans. Despite strict regulations on whaling , there are still a number of countries such as Japan and Iceland which use loopholes to continue commercial whaling. Despite continued whaling by a few rogue nations, some species such as humpback whales are on the rise since the 1986 commercial whaling moratorium.

Kliens-Butterflyfish, photo courtesy of Robert Woods


Between 1.15 and 2.41 million tons of plastic enter the ocean every single year. The Great Pacific Garbage Patch, which is a collection of rubbish in the Pacific Ocean is now three times the size of France. Animals can get tangled in the huge amount of plastic which litter the ocean, and the plastic smothers and destroys coral and sponges. Plastic bags are also often mistaken for food by sea turtles, and they either become trapped or eat the bag which clogs their digestive system. Plastic continuously breaks down resulting in little pieces of “micro-plastic” that are consumed by a variety of marine life, including several species that humans like to catch and eat.


Irresponsible Fish Farming

As more people inhabit the Earth, there is more demand for food, and one response is to grow as many fish as quickly as possible, regardless of the negatives. Unfortunately, chemical pollution can easily occur since fish farms  often rely heavily on medications, and are a source of excessive nutrients from left over artificial fish food and excrement. This can have destructive effects on natural habitats in the sea, as well as accidental release of farmed fish which are destroying native stocks and passing on diseases.


Habitat Destruction

Most of the above issues are contributing to habitat destruction, and coral reefs are one of the most seriously impacted ecosystems. Global warming contributes to the decline of many coral reefs. Over the last century, the temperature has risen by around 0.1 degrees Celsius. Whilst this might not sound like much to you, it has resulted in coral bleaching; a phenomenon whereby heat stressed corals expel their symbiotic algae. These algae are necessary to keep the coral alive and their loss lowers the resilience of coral reefs. Other things contributing to habitat destruction are coastal development, pollution (for example, runoff or oil spills), clearing mangrove forests for shrimp production, and deep-sea trawling.  With increased habitat destruction, comes fewer places for fish to live, and to use as their nursery and feeding grounds, leading to populations declines.


What Can You Do?

Whilst you might be left feeling quite deflated after hearing about the many different dangers that fish in our ocean face, there are a great number of positive changes which are being made by governments around the world. Bans have been put in place on fishing in some areas, such as Hawaii who are currently proposing a ban on all aquarium fish, and California which has a statewide network of marine protected areas. Changes that you can make as an individual include:

  • Reducing your carbon footprint
  • Using less plastic
  • Ensuring the fish you eat is sourced ethically and sustainably
  • Getting involved in beach cleanups
  • Only buy aquarium fish which have been bred in captivity
  • Voting for politicians that support a healthy environment
  • Supporting conservation organizations that are working to save our oceans