Biodiversity and our food habits

The seas and oceans are incredibly rich in biodiversity. Beyond the 200,000 species of fish we’ve cataloged so far—and there may be millions more—are cetaceans, seals, mollusks, sponges, algae and coral, right down to the tiniest zooplankton and phytoplankton, all of whom live in complex ecosystems that are not well understood.

Ph. by Photo by NOAA on Unsplash

We have mapped the world, and we longer fill in the blank spaces with strange monsters and fantastical animals conjured from our imagination. But maybe we should, because all life on this planet has not yet been discovered—far from it. Scientists have cataloged just under two million species of animal to date, but biologists estimate that altogether there are about ten million multicelled organisms on our planet. Undoubtedly the greatest discoveries await us in the ocean.

Morten A. Strøksnes, Shark Drunk, Penguin Random House, 2017

The seas’ inhabitants are still in large part unknown. Yet among these countless fish, we tend to concentrate on just a handful of names, those considered to be of commercial and gastronomic interest: cod, bream, bass, tuna, salmon… our appetites, together with the ever-greater efficiency of industrial fishing and the pollution we create, are putting the survival of entire species at risk.

The numbers

According to the FAO, over 33% of commercial fish species are being fished at biologically unsustainable levels, with another 60% being fished at the limits of sustainability. The latest figures show 90.9 tons of wild fish are caught annually.

The consequences

As well as the excessive pressure being put on fish stocks, human activity is having an impact on the climate, the physiochemical properties of the ocean and more generally on all ecosystems. This results in a loss of biodiversity both in terms of numbers of extant species and in the systemic health of ecosystems.

This progressive depletion could have repercussions for the well-being and the very survival of humanity. Over three billion people depend on the biodiversity of the seas and coastal areas for their sustenance and an estimated 37 million people are employed in small-scale fishing, most of them in developing countries. Directly and indirectly, the oceans provide a livelihood to around 200 million people.


We can all contribute to the conservation of marine biodiversity. We can form virtuous connections through our choices:

  • As consumers, we must adopt more responsible practices:

    Vary our diet, choosing less-fashionable fish that are often tastier and cheaper;

    Look for the right size! Every fish has a minimum size below which it can’t be caught or sold;

    Avoid carnivorous farmed fish, opting instead for more sustainable species like bivalves (oysters, mussels, scallops and clams)

    Choose local fish according to their seasonality; asking questions of our fishmonger to learn how, where and when our fish is caught.

  • Fishers must avoid putting excessive pressure on fish stocks. Sustainable fishing means responsible resource management, taking only certain species of fish in quantities that the ecosystem can sustain without permanent damage. Slow Food supports integrated production methods (where fishing is practiced in combination with agriculture, tourism and crafts) which diversify revenue streams for fishers and ease pressure on fish stocks.

  • Companies can contribute by developing tools made with biodegradable materials and ending the production of plastic fishing equipment. They could develop apps to help small-scale fishers access wider markets and create direct contact with consumers.
  • Institutions must work to effectively regulate fishing and put an end to all excessive, illegal, undeclared and unregulated catches, as well as to destructive fishing practices. Management plans based on scientific knowledge must be drawn up in order to revive fish stocks as quickly as possible.

Discover positive fishing stories at Slow Fish. Fishers, conscious consumers, companies and organizations will show you what they’re doing to promote richer, healthier seas, and how you can help protect the precious biodiversity they contain.


  • FAO, 2018, The State of the World Fisheries and Aquaculture
  • Heinrich Boll Stiftung & Schleswig-Holstein, 2017 Ocean Atlas – Facts and Figures on the Threats to Our Marine Ecosystem
  • UN Sustainable Development Goals 2015 – Goal 14: Life Below Water
  • Peter Greenberg, Four Fish Penguin Books, 2011
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