- There are more than 35,000 identified and described fish species in the world.
- An estimated 80 fish species have gone extinct over the last five centuries.
- More than 3,000 fish species are threatened with extinction today.
- One-third of wild fish stocks are overexploited. This is an increase from 10% in the early 1970s.
- The share of fish stocks that are overexploited has been relatively stagnant over the last decade.
- Overexploited fish stocks vary a lot by region – from around 10% to over 60%.
- We now produce more seafood from aquaculture than wild fish catch. Catch from wild fisheries has changed very little since 1990.
How many different fish species are there in the world today? As with any other group of wildlife, it’s hard to say with complete certainty: this is because there is always the possibility that there are bird species that we’re yet to discover. New animal species are unearthed every year.
What we can say is how many species have been identified, named and described.
In the chart we see the number of described species across a range of taxonomic groups. Due to the issue of finding and counting every species, these are likely to be underestimates.
We see that there are more than 35,000 described fish species in the world.
Extinctions have been a natural part of the planet’s evolutionary history.1 Most bird species that have existed on Earth will have now gone extinct.
But what most people are interested in is how many species have gone extinct in recent history. How many species have modern humans driven to extinction?
The IUCN Red List has estimated the number of extinctions over the last five centuries. Unfortunately we don’t know about everything about all of the world’s species over this period, so it’s likely that some will have gone extinct without us even knowing they existed in the first place. This is likely to be an underestimate.
In the chart we see these estimates for different taxonomic groups. It’s estimated that 80 fish species have gone extinct since 1500.
An estimated 80 fish species have gone extinct in recent centuries. How many more are threatened with extinction today?
The IUCN Red List of Threatened Species evaluates species across the world for their level of extinction risk. It does this evaluation every year, and continues to expand its coverage.
The IUCN has not evaluated all of the world’s known species; in fact, in many taxonomic groups it has assessed only a very small percentage. Only 1% of known insects, for example, have been assessed. The coverage for fish is better, but still incomplete: only 60% of known bird species have been evaluated for their extinction risk.
We should also be clear about what ‘threatened with extinction’ actually means. The IUCN labels a species as threatened if it falls into one of the following three categories.
- Critically endangered species have a probability of extinction higher than 50% in ten years or three generations;
- Endangered species have a greater than 20% probability in 20 years or five generations;
- Vulnerable have a probability greater than 10% over a century.
In the chart we see the number of species threatened with extinction across taxonomic groups. More than 3,000 fish species are threatened with extinction across the world.
There are a range of environmental pressures that put fish at risk of extinction: overfishing; climate change; changing ocean chemistry; fresh and marine water pollution; among others. The intensity of these pressures varies significantly across the world.
In the map we see the distribution of threatened fish species across the world.
A key concern for the sustainability of global patterns of seafood consumption has been the overexploitation of wild fish stocks. If the amount of wild fish we catch exceeds the rate at which fish can reproduce and replenish, populations will decline over time. Such populations we would call ‘overexploited’.
This is based on a metric called the ‘maximum sustainable yield’ (MSY) – the upper limit to the amount of fish we can harvest without depleting the existing resource. If fishing rates are lower than the MSY, a stock is defined as biologically sustainable. If harvest is higher than the MSY, it is overexploited.
In the visualization here we see the share of global fish stocks which are overexploited and the share that are biologically sustainable. Sustainable stocks have fallen from 90% in the 1970s to 66% in 2017.2 One-third of global fish stocks are now overexploited.
We can also see, however, that most of the decline in sustainable fish populations occurred through the 1970s and 1980s. Over the past few decades there has been a marked slowdown – or plateauing – of overexploitation. This is in part owed to the fact that increased demand has instead been met by aquaculture (fish farming) rather than wild catch.
It’s estimated that 79% of current fish landings come from biologically sustainable stocks.3
Around one-third of global fish stocks are overexploited. But the state of fish stocks varies significantly across the world’s oceans.
In the chart we see the share of fish stocks that are overexploited by region. Overexploited fish stocks are defined as stocks where fish catch excess the rate at which they can biologically restore.
By region, this can vary from as low as 13% to more than 60%.
Global production of fish and seafood has quadrupled over the past 50 years. Not only has the world population more than doubled over this period, the average person now eats almost twice as much seafood as half a century ago.
This has increased pressure on fish stocks across the world. Globally, the share of fish stocks which are overexploited – meaning we catch them faster than they can reproduce to sustain population levels – has more than doubled since the 1980s and this means that current levels of wild fish catch are unsustainable.
One innovation has helped to alleviate some of the pressure on wild fish catch: aquaculture, the practice of fish and seafood farming. The distinction between farmed fish and wild catch is similar to the difference between raising livestock rather than hunting wild animals. Except that for land-based animals, farming is many thousand years old while it was very uncommon for seafood until just over 50 years ago.
In the visualizations we see the change in aquaculture and capture fishery production from 1960 onwards. What’s striking is that global wild fish catch has not increased since the early 1990s and instead remained relatively constant at around 90 to 95 million tonnes per year. Fish farming on the other hand is growing very rapidly, from 1960 until 2015 it has increased 50-fold to over 100 million per year.
In the 1960s, aquaculture was relatively niche, with an output of a few million tonnes per year. Particularly since the late 1980s, annual production has increased rapidly. In 1990 the world produced only 17 million tonnes. It now produces over 100 million tonnes.
As we see, aquaculture production has now surpassed wild catch. It has absorbed almost all of the growth in global demand in recent decades and will continue to play a critical role in protecting wild fish populations as demand for seafood continues to rise.
One of the charts presents FAO wild fishery catch data, broken down by region. Here we see a steady increase in fishery catch until the mid-1990s, when this trend typically levels out in the range of 90-95 million tonnes per year.
In the other chart we present revised data published in Nature by Pauly and Zeller (2016).4
Here, the authors argue that catch from small-scale fisheries is typically under-reported to, and published by the FAO. The authors write:
“This data set, however, may not only underestimate artisanal (that is, small scale, commercial) and subsistence fisheries, but also generally omit the catch of recreational fisheries, discarded bycatch and illegal and otherwise unreported catch, even when some estimates are available. Thus, except for a few obvious cases of over-reporting, the landings data updated and disseminated annually by the FAO on behalf of member countries may considerably underestimate actual fisheries catch.”
The authors’ revised figures therefore show significantly higher fishery catch which peaks around 1996 at 130 million tonnes, before declining to 109 million tonnes in 2010. Although different in magnitude to that of FAO figures, these revised trends support the trend of a global maximum in wild fishery catch (but now with a significant decline). As shown in both charts, the majority of this decline has resulted from falling industrial catch; small-scale artisanal catch actually increased over this period.
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