Key points:
- In this post, we summarise some of the key results of our research on animal welfare in wild-caught shrimp fisheries.
- The full paper is freely available as a preprint here, while it undergoes peer review before publication in a journal. It's a long and detailed paper, with many fancy tables and graphs - I would encourage you to check it out.
- We conducted a review of shrimp fisheries and interventions that could improve shrimp welfare in wild-catch fisheries.
- We calculated the number of shrimp caught in the world's wild-catch shrimp fisheries. This allows us to see how many shrimp are caught in each country and what species of shrimp they are.
- Our paper also includes an in-depth analysis of each of the world's top 25 countries, by number of shrimp caught.
The authors of the full paper are: me (Ren Ryba), Prof Sean D Connell, Shannon Davis, Yip Fai Tse, and Prof Peter Singer.
1. General overview of wild-caught shrimp fisheries
There are many, many, many shrimp caught in wild-catch fisheries each year. Specifically, it is estimated that around 37.4 trillion shrimp are caught in wild-catch fisheries each year, and that is probably an underestimate.
Broadly speaking, there are three types of shrimp:
- Caridean shrimp (781 billion caught each year). These shrimp are actually more closely related to crabs and lobsters than to the other two types of shrimp, which is why the evidence for shrimp sentience tends to be focused on this group. They are relatively small (e.g. a few centimetres). Caridean shrimp are mostly caught in cold-water (temperate) fisheries. Important caridean shrimp fisheries include the North Sea shrimp trawl fishery (the Netherlands, Germany, Denmark, and the UK) and the North Atlantic and Pacific shrimp trawl fisheries (USA, Canada, Russia, Greenland).
- Penaeid shrimp (287 billion caught each year). These shrimp are mostly in warm-water (tropical) fisheries, and they physically tend to be a bit larger in body size. Important penaeid shrimp fisheries include the trawl fishery in the USA, trawl and small-scale fisheries in Latin America, and trawl and small-scale fisheries in East and South-East Asia.
- Sergestid shrimp (36.3 trillion caught each year). This group includes the "paste shrimp", Acetes japonicus. Sergestid shrimp are tiny, sometimes even microscopic. These are very common in small-scale fisheries in East and South-East Asia, as well as East Africa.
It's important to understand that these three types of shrimp are distinct. Caridean shrimp are actually more closely related to lobsters, crabs, and crayfish than they are to penaeid and sergestid shrimp. There are important differences in their biology, their evolutionary histories, the corresponding fishing industries, the amount of research that has been conducted on sentience, and - most importantly - the tractability of welfare improvements in fisheries. Those differences are explained in more detail in the full report.
(Credit: Shrimp silhouettes in the evolutionary tree are from phylopic.org. Caridean shrimp: Maija Karala. Penaeid shrimp: Almandine (vectorized by T. Michael Keesey). Crab: Jebulon (vectorized by T. Michael Keesey). Lobster: Guillaume Dera.)
We can also distinguish between two major types of shrimp fisheries:
- Industrial trawl fisheries. These may be large, high-power trawler vessels that can conduct journeys for weeks or months at a time. These vessels may be technologically sophisticated, with many processing, packaging, and storing shrimp on-board. Industrial trawl fisheries are common in both developed (e.g. North America, Europe) and developing (e.g. Latin America, China, South Korea, and many South-East Asian) countries.
- Small-scale fisheries. These may involve small boats or by wading into the water from the shore. There are small-scale trawls, and there are also many other gear types. Small-scale fisheries are more common in developing countries (especially South-East Asia), though with some exceptions (e.g. Ireland).
Some countries combine both types of fisheries (especially in Latin America, China, South Korea, and India).
Beyond the impacts on shrimp themselves, there are some other challenges associated with shrimp fisheries around the world:
- Bycatch. The weight of catch from shrimp trawlers sometimes reaches even 80-90% non-target animals. This includes other shrimp and invertebrates, finfish, turtles, marine mammals, and seabirds.
- Enforcement. There are many countries, particularly developing countries, that struggle with enforcing fisheries regulations.
- Environmental degradation. Many trawl fisheries have caused overfishing. Beyond the environmental effects, this also means that it has become harder in many countries for fishers to catch enough shrimp to earn a living.
- Poverty. A good example of this is the small-scale fisheries in Vietnam, where coastal communities are disproportionately poor and have comparatively little political representation. Poverty interacts with environmental degradation and enforcement in complex ways - any policies or interventions around fisheries probably need to be incorporated into a more overarching poverty strategy.
- Human rights violations. There is well-documented evidence of forced labour (modern slavery) aboard fishing vessels, most notably aboard trawlers in Thailand. In Thailand's fisheries, the prevalence of forced labour was estimated at 14% in 2019. This is often exacerbated by social crises and/or government policies in neighbouring countries - for example, people forced into labour aboard Thai vessels are often Rohingya men who are fleeing ethnic cleansing/genocide in Myanmar (often exacerbated by restrictive refugee policies in neighbouring countries)
- It's difficult work. Even on trawlers in well-regulated countries, shrimp fishing is pretty intense and even dangerous work.
2. Shrimp welfare interventions in wild-catch fisheries
In industrial trawl fisheries, some promising interventions are:
- Installing electrical stunners on trawl vessels
- Reducing trawl durations
- Reducing trawl weights (having less weight of prawns in the trawl net before it is hauled onto the vessel)
- Optimising on-board logistics to reduce the shrimp processing time, thereby preventing asphyxiation and reducing temperature stress
- Continuing existing work on reducing bycatch
In small-scale fisheries, particularly in developing countries, it may be more plausible to instead focus on:
- Finding ways to help governments enforce existing fisheries regulations
- Optimising shrimp storage and hygiene processes on-board and on land to reduce spoilage, thereby reducing the wastage of shrimp due to hygiene or contamination issues
- Encouraging people to modify the way shrimp paste is made to contain a lower content of shrimp
And crucially, it would be really useful to conduct extra research. This includes:
- Basic (experimental) research on shrimp sentience. There are a few important knowledge gaps in the evidence for shrimp sentience and whether sentience differs between shrimp groups.
- Applied research on shrimp welfare, such as what capture methods and on-board conditions cause the most stress.
- Improving the data on the number of shrimp killed by shrimp fisheries in each country. There are some well-known problems with fisheries data in general, and shrimp fisheries in particular have high levels of bycatch and unreported catch.
3. Shrimp numbers for every country in the world + cool tables and graphs
There are lots of cool tables and graphs, including some pretty maps, in the paper. I'd encourage you to check those graphs out.
We also produced estimates of the shrimp catch, by species, for every country that has reported catch in the FAO fisheries data. So if you want an estimate of the number of shrimp caught by species in your country, this may be what you're after. These tables are freely available for download here.
Acknowledgements
I would like to note that our numbers are based on the estimates of body weights of each shrimp species, calculated by Daniela R. Waldhorn and Elisa Autric at Rethink Priorities. We would not have been able to make these cool tables and graphs without that piece of research.
Cover photo: Pixabay
Afterword: Are they called "shrimp" or "prawns"?!
This was a great rabbit hole. Some people distinguish between "shrimp" and "prawns" on biological grounds, arguing that some species are only correctly called "shrimp" while others are only correctly called "prawns". However, I think that the only defensible conclusion is that both "shrimp" and "prawns" are terms for the same thing, and the one to use basically depends on the country you're in.
During my 2023 visit to London, when I arrived at the tattoo studio for my appointment to get a shrimp tattoo, the first thing the artist asked was: "So, what's actually the difference between a shrimp and a prawn?" I realised that even with my expertise in marine ecology and shrimp welfare, I had no clue.
The Wiktionary entry for "shrimp" gives this definition: "Any of many swimming, often edible, crustaceans, chiefly of the infraorder Caridea or the suborder Dendrobranchiata, with slender legs, long whiskers and a long abdomen."
The Wiktionary entry for "prawn" gives these definitions:
Both refer to the suborder Dendrobranchiata, and "shrimp" adds on the infraorder Caridea. These are two non-overlapping groups that are both contained within decapod crustaceans (see above in this post - Dendrobranchiata includes both penaeid and sergestid shrimp).
Those same entries also tell us a bit about the etymology:
It seems fair to say that "shrimp" and "prawn" both originated with the arbitrariness and whimsy typical of word origins, and that both terms are defined today to refer to mostly the same group of animals.
I've seen some people claim that "shrimp" and "prawn" are defined biologically, with particular morphological traits distinguishing between them - such distinctions tend to make reference to minute characteristics of the gills, the shell, or how the legs are spaced. If you accept the above definitions, it does admittedly seem to be true that animals in the infraorder Caridea can be called "shrimp" but not "prawns". Perhaps biologists follow this usage. But I think it's fair to doubt that the general public, or even farmers, are in the habit of checking the gill characteristics or reading the latest taxonomy papers before they risk using the wrong word.
It seems far more plausible to me that there is a much simpler rule: people in some countries say "shrimp", while people in other countries say "prawn". I'd bet that Australians would say "prawn" even if you show them an animal from the infraorder Caridea. (We Australians in particular get sensitive about this.) There's even a lobster that is called a "prawn" in the United Kingdom - a lobster! Furthermore, both taxonomy and word meanings change over time, and classifications of animals are frequently revised, so I'd be wary of any strict definition based on taxonomy. This is basically the same conclusion reached by Gillett and by Rethink Priorities.
I found this gem published in a 1969 taxonomic study: "There has been much confusion in the usage of terms prawns and shrimps. At the Prawn Symposium of the Indo-Pacific Fisheries Council held at Tokyo in 1955 it was decided that the term prawn should be applied to the Penaeids, Pandalids and Palaemonids, while the use of the term shrimp should be restricted to the smaller forms belonging to other families. According to this most of the forms of economic importance here are to be termed prawns."
I love the idea of a roomful of biologists in the 1950s thinking that the best thing to do in Toyko is to have a heated debate about marine invertebrate terminology. And I thought I needed to get out more.
Now, do not get me started on the difference between a pigeon and a dove.