One of the major ambiguities in the sustainable fisheries world is the issue of prawns, it is the methods as to how these are caught or reared which deems their sustainability to eat. Prawns have been given a number of names to market them and increase the appealability. But generally speaking; Prawns, Shrimp, Langoustines, Scampi, Nephrops, Dublin bay prawn, Crawfish and Crayfish are all very similar.
Prawns and Shrimps are one and the same when it comes to fisheries however, biologically they belong to two different species groups, however I will not confuse the matter here. Prawns or Shrimps refer to freshwater or saltwater Crustations in the class Malacostraca. The head and body is enclosed in a protective carapace and they use their muscular abdomen to swim.
Scampi, Langoustines, Dublin bay Prawn and Nephrops are also one and the same, and Crawfish and Crayfish is just the freshwater version. The Latin name Nephrops norvegicus refers to a similar Crustation to the prawn, the only major difference is that this one has claws like a lobster.
The methods of fishing for both prawns and Nephrops are very similar. The main method of wild capture is by trawl. Trawling is one of the most devastating methods of fishing. You cam compare trawling to running a fine pick comb over the ocean floor, tearing up everything in its path and catching anything and everything. Because prawns are very small a fine net size is used In this fishery creating large numbers of bycatch. The video below demonstrates this devastation;
When we talk about bycatch in this fishery, we mean phenomenal numbers of bycatch.
There are 2 main prawn fisheries, cold water and tropical. The cold water species are generally the small ones you get in sandwiches and jacket potatoes, the bigger ones such as tiger prawns are from the tropics. In cold water prawn fisheries approximately 5kg of bycatch is caught for every kg of prawns harvested, You might think, well the only by catch is crabs and starfish as that’s all we have in the seas at these latitudes; however you would be very very wrong. Nephrops is mainly found around Europe, the Baltic and parts of the Mediterranean and the methods of capture are the same as those in the cold water prawn fishery.
The species which occur as bycatch in coldwater prawn fisheries are listed below;
• Grey Gunard
Therefore The capture of prawns is further eating into our depleted target fish stocks, if prawn trawlers do not have permits or quota to land these species then they add further to the already detrimental bycatch of fish.
There is however several alternative and more sustainable prawn fisheries you can look for. Generally coldwater prawns from Arctic oceans around Norway, Iceland, Denmark and Canada are the best choices. Look for those which are Trap or Pot caught, Spot Prawn from British Columbia are on the green list in the SeaChoice seafood guide, however the food miles to the UK for this species is great so look out for other UK or north sea pot caught products.
I have yet to find pot caught prawns in any UK supermarkets, but ask your local fishmonger if he can get hold of them. Also be very careful, there is some MSC certified cold water prawns on the market, mainly from Canada, Greenland and Iceland from the companies Lyons which can be found in Sainsbury, Sainsbury own brand cooked peeled prawns and Royal Greenland which can be found in Tesco and Sainsbury. However if you go to the MSC accreditation website you can see that these fisheries still use trawling devices, although otter trawls, are still detrimental to the environment. But if you must buy prawns and you can’t find pot caught then this is the next best option.
Now to move on to tropical prawn fisheries… where to begin, this is one of the most destructive fisheries on the planet, not only destroying marine habitats but also those on land. I will start by discussing tropical trawling. The issues with trawls are similar to that of cold water fisheries, the major difference being that there is a vast increase in the biodiversity of marine life in the tropics especially benthic fauna, therefore there is a great deal more destruction.
In the tropics as much as 10kg of bycatch is caught for every 1kg of prawns harvested, this value is actually an improvement over the last decade due to bycatch excluder devices where the value used to be up to 20kg of bycatch! The species caught are also more tragic as many are endangered and slow growing species, below is a list of commonly caught bycatch in these trawl fisheries;
• Sharks including rare great white and grey nurse sharks
• Sea Snakes
• Seahorses, Pipefish and Seamoths
• Bony Fishes
• Echinoderms, Starfish
• Habitats such as seagrass beds, coral reefs
Worrying figures were published by the Environmental Justice Foundation in 2003. They estimated that at one point approximately 150,000 turtles were being caught as bycatch each year in prawn trawling fisheries alone! now that is a huge number, I find it hard to even imagine that number of turtles existing let alone being killed every year. It is a rare treat to come across a turtle when scuba diving or snorkelling as many will know if you have ever been blessed with this experience. The age of sexual maturity can be up to 30-50 years old in some turtle species, no wonder many are highly endangered! And we haven’t even touched the environmental devastation yet!
Prawn farming is equally as destructive, the high demand worldwide for cheap prawns to be added to everything from fine dining to noodle pots has created a booming business in prawn ponds. These ponds are used to grow vast numbers of individuals in very small areas of space, if you thought salmon farming was intensive, you havn’t seen nothing yet!
Prawn ponds are commonly created in cleared mangrove area in the tropics, particularly in South East Asia. Mangroves are extremely important environments providing fish nurseries, coastal protection and water treatment eco-services. The destruction of these is a huge issue which has caused losses of great cultural heritage, reduction in water quality and even amplified the effects of events such as the 2004 Tsunami!
These prawns are reared in nurseries at intensities of 150-200 animals per square meter and then moved to the grow out stage where they are stocked at 10-30 animals per square meter, keep in mind that when fully grown these can be 18-36 cm each. These ponds are putrid, creating masses of waste water and needing to be constantly aerated and pumped with antibiotics! Not an appetizing thought! So in all its best to completely avoid tropical prawns altogether. There is however one exception to the rule, a new farming method known as organic farming has been shown to be more sustainable. These prawns are farmed on land which has not been cleared of important habitats, are stocked at low densities and only fed natural food sources, however there are huge food miles attached to these prawns and so still not really a good choice.However, these can be found in supermarkets such as Tesco and Sainsbury.
As a final statement your best choice is pot caught cold water prawns or Nephrops, if you can get hold of them, otherwise bypass the prawn cocktail and go for a different dish maybe Tilapia, Mussels or Oysters which were recently named the most sustainable seafood’s by the Marine Conservation Society, you can check out their brand new and updated Fish Guide here.
For more information The Environmental Justice Foundation have produced a consumers guide to prawns found here.
The BBC also produced a informative docunetary in 2004 entiteled ‘The Price of Prawns’ which is unfortunatly not avaliable but would be grat for them to update and reair in the future!