Over-fishing and the future of food security

Overfishing Catch

The use of fishing cages such as this one from Koh Tao is an selective technique that removes many non-valuable but ecologically important fish species from the reefs.

One of the things that divers and fisherman all around the world are asking is “where have all the fish gone?” Fish, sharks, and other seafood stocks of nearly every species have been depleted around the globe due to increasing human populations and desire to eat seafood. Over-fishing is one of the leading threats to the balance and health of our planet’s marine ecosystems.


Fish are an integral part of any marine ecosystem, and play important roles in consuming algae, cycling nutrients, removing detritus, and through symbiotic relationships with other animals. For a coral reef, without fish algae would overgrow everything and the reef would perish. In Pelagic areas,without the fish, tiny bacteria and amoeba like organisms thrive in huge numbers, eating up all of the oxygen in the water and killing all life around them. This is causing ‘dead zones’ to appear in the sea, where nothing can live. In the 1980’s there were 120 spots, by the 90’s that increased to 300, and today it stands at over 400 (some are up to 70,000 sq. Km!). At current rate, within the next 100 years we will see the 6th mass extinction of marine life in our earth’s long history (the last one wiped out the dinosaurs).


As of 2014, 2.6 billion people live within 100 km of a coastline, and it is estimated that seafood is the primary source of protein by more than 1 billion of the world’s poorest people.  When we look to the future the problem becomes even bigger. In 2050 global populations are expected to rise to 9 billion people. As the productivity and space for land-based agriculture begins to reach its limits, where will the food for all of these people come from? With 71% of our ocean covered in oceans, the most important developments in future food supplies will have to be from our marine areas. But without proper management these vast resources will be lost before those demands can be met.


In today’s fishing industry, as a specie’s abundance declines, their value rises on the market. This gives fisherman the incentive to then catch more of that species, resulting in a positive feedback loop ending in the collapse of entire populations and related ecosystem goods and services.


Overfishing 1

These fish are from an illegal catch by a fisherman using cages in the ‘no-take’ zone around Koh Tao

But it is not too late for all species,this problem is addressable, all we need to do is watch what we put in or take out of the sea. I am not saying to stop eating seafood, but if each of us reduced our consumption by half, that would fix more than half the problem. As much as 80% of what is pulled up by a boat is considered by-catch, and with little or no value these animals are thrown back in the sea. So for every 1 fish we consume, many more fish and invertebrates had to perish. In the case of shrimp fishing, the primary method is using deep sea trawlers, which literally remove everything from the seabed. Choosing farmed or captive raised seafood products greatly reduces these problems involved with by-catch.


Aquaculture and farming of fish is one of the most important ways that we can feed a hungry human race, provide food security for the world;s poor, and reduce our pressure on natural ecosystems. We have come so far in livestock husbandry and farming that in developed countries few people ever eat a wild-caught animal. Why then have we done so little to develop the same techniques for commercially important marine species?


Since often only wild-caught species are available, be smart about the species that you do eat, generally the larger the fish the more important it is to the ecosystem. If you must eat fish, avoid predator fishes and large fishes such as Tuna, Shark, and Barracuda. If we all make a conscious effort, momentum will grow and we can avoid losing all that we love and cherish. There is still much work that needs to be done at the regional and international government levels to address the management of fisheries, but we should not rely on governments alone. To solve this problem, it is only up to YOU and the choices that YOU make.


Want to learn more about how over-fishing and climate change are affecting our planet’s oceans, check out the following other links on our page:

Seahorses are often caught as by-catch by shrimp trawlers. These three seahorses where caught by a boat near Koh Tao, and are the seahorse H. trimaculatus, listed as 'Vulnerable' by the IUCN.

Seahorses are often caught as by-catch by shrimp trawlers. These three seahorses where caught by a boat near Koh Tao, and are the seahorse H. trimaculatus, listed as ‘Vulnerable’ by the IUCN.

Plenty of fish in the sea?

Caught Between a Net and a Hard Place

New Heaven Pledges to be Fin Free

Thailand Shark Sampling Expedition

Local Coral Reef Protection Success

Tracking Climate Change on Coral Reefs

Marine Conservation in a High-Carbon Dioxide World

Caught Between a Net and a Hard Place