What have fish got to do with climate change? Scientists and lovers of the sea alike have observed the degradation of water ecosystems earlier than other signs of climate change. Waterways, considered infinite and eternal, had already suffered greatly from the first wave of industrialisation in the XIXth century. Major European rivers such as the Thames or the Seine were mostly dead zones before drastic waste management regulations were put in place to re-establish life in these streams. Today, a larger crisis looms in the face of our undying appetite for the products of the sea.

Fishing since B.C. 50,000

Humans do enjoy a fish here and there. Paleohistorians even claim that fish was part of Homo habilis, and then Homo sapiens’ diet before hunting was a thing. Fish, oysters, crabs and other food sources from the sea were always far easier to come by than hunting a powerful buffalo or a flying gazelle.

Fishing techniques evolved to become more efficient, but the limits of conservation technology (fridges were not around) long limited the scope of the fishing industry. A notable exception is the trade of salted and dried cod, most probably initiated by the Vikings around 1,000 AD, who developed trade routes from Lofoten to Lisbon for this particular fish. With industrialisation came the first large-scale fishing boats and deep-sea fishing. What was a coastal and mostly local activity was about to go global.


Fish, and seafood in general has been hailed as one of the go-to protein sources to replace the carbon-consuming and land-grabbing cattling industry so damaging to the environment today. Symbolic of its universal reach, seafood consumption levels are not correlated to income as directly as meat. 

Today, fish contributes to 17% of animal protein in the world, but this figure rises to 26% in the developing world. 97% of fishermen live in the developing world, making fishing the first income-generating food-related activity. For these cultural, economic and historical reasons, the global demand for products of these has grown twice as fast as the human population since 1961.

Wild fish are all at risk

Wild fish stock failure has become evident in numerous parts of the world. Estimates vary between 75-90% of marine wildlife loss since 1970The Food and Agriculture Organisation of the UN considers that 9 commercial species out of 10 is either fully or overfished. Extremely destructive fishing practices such as trawling, dredging or electric fishing make no distinction among species, simply catching everything and anything that can be caught, and throwing overboard the non-commercial species.

“The erosion of ecosystem health has many causes, but one global consequence. Our oceans are emptying”

Global fish production reached about 171 million tonnes in 2016. Of these, 93 million tonnes comes from the wilderness each year. The rest is “cultivated” in artificial aquaculture, also known as fish farming. However, these installations – as for other forms of industrial farming – concentrates large amounts of living matter over very small areas. This, in turn, creates cess and insalubrious environments. Not only do these farms stink, but they also make for carbon emission centres, with the slow decomposition of live matter.

Dead zones, due to overfishing, unbalanced ecosystems and oxygen depletion, have become larger and larger, in rivers, coastal areas and lakes alike. Some zones have become so large that the phenomenon is now visible from space.

Bring back Baywatch

Thankfully, our monitoring techniques have done huge progress. What used to be an untrackable zone of mystery (and lawlessness) is now watched over by dozens of satellites. This has allowed us to ring the alarm and understand the dynamics of the fish crisis.

As NASA puts it quite dryly, “It’s no coincidence that dead zones occur downriver of places where human population density is high. Fertilizer-laden runoff triggers explosive planktonic algae growth in coastal areas. Themicrobes decompose the organic matter, using up the oxygen. The mass killing of fish and other sea life often results.” Space science has already done a lot to track with more efficiency bad practices and overfishing. Global Fishing Watch has released a satellite imagery study which proved both the existence of bad fishing and the concentration of the problem on a few countries and practices.

Read also: Measuring Climate Change: What are Marine Protected Areas

A thriving ecosystem might have withstood the more insidious effects of climate change like ocean acidification and temperature rise. The most fragile species – corals, for example – are the ones that are the slowest to build up and that need the greatest stability in external conditions. The erosion of ecosystem health has many causes, but one global consequence. Our oceans are emptying and safe havens for marine wildlife are disappearing. After all, our great-great-great-great grandparents were fish too. 

Do you know someone working on overfishing? Send them over to our Call for Projects on Overfishing in Denmark.

Cover picture credit: Ocean Agency / XL Catlin Seaview Survey / Richard Vevers