This is the most important aspect to consider. Consumption of shrimp like everything else has its fair share of impact on the environment, this portion will address those and my goal is to educate consumers to make a more informed decisions and not be swayed by sensationalist stories. All the information out here will be in the context of shrimps/prawns originating from India. First we will analyze the environmental impact / negative externalities of wild caught shrimp and then move on to farmed shrimp.
Wild Caught (Industrial/Commercial Fishing)
Majority of the wild caught shrimp from the eastern coast of India are from trawlers. The size of trawlers are not as big as the ones you will find in developed countries or in countries such as Thailand and Vietnam, in fact they are smaller than the classification for trawlers as per the International Maritime Organizaton (IMO). However what they lack in size they more than enough make up for it in numbers.
One of the biggest damages from such a fishing practice is the by catch associated with it. For more information please read this page on the study of trawl fishing in the eastern coast of India: Chicken Feed
Apart from bycatch, there is increasing concerns that existing regulations and/or current enforcement levels are not sufficient for sustainably managing our fisheries. Statistics from the fisheries department are tough to work with, since they include both wild caught and farmed output. However other techniques have been developed such as: Rays of Hope
Going by the stories of my father and uncles, the catch has greatly reduced. Some of the steps needed to sustainably manage them would include strict regulations and monitoring of the number of fishing vessels permitted to engage in fishing. Establishing more marine parks. No fishing during breeding season (monsoons) currently this is practiced but the no fishing period varies from state to state. What effectively happens is that when Odisha has this ban, you will have trawlers from West Bengal operating in the waters, nullifying the very purpose of the fishing ban. However a silver line is that during monsoons time, the weather isnt very conducive for the trawlers to go on a voyage, so that restricts damage to some extent.
Another damage from this fishing practice is with respect to the endangered Olive Ridley turtle, which get entangled in the nets. However this is effectively countered by enforcing a fishing ban during the nesting season and once the baby turtles hatch. Trawlers are required to be equipped with the TED (turtle exclusion device).
Overall effective govenment regulations combined with enforcement will ensure that a typical “tragedy of the commons” scenario does not occur. Other mechanisms to promote sustainability is by promoting eco labelled products. However a downside of this strategy is that there are too many labels in the market, and most consumers are not aware of the details.
Farmed Shrimp (Shrimp Aquaculture)
Farmed shrimp accounts for 100% of my total sales. As of now most of the shrimp consumed in the world are farmed shrimp. Farmed shrimp have their own share of negative externalities. I will list them and give my views.
Farming shrimp using seed obtained from the wild is highly damaging to the environment. During the process of collecting the wild frys and segregating them, there is a huge bycatch of other species of fish and other creatures. Such a systen of aquaculture is termed as Capture Based Aquaculture. If not monitored properly they result in damaging the capture fishery base. It is my personal belief that such kind of unsustainable practices have resulted in the drastic decline of output from the Chilika lake. The alternative to procuring shrimp fry from the wild would be to obtain them from hatcheries. This is a sustainable model and it is better for the farmers too, since they will have access to disease free seed (something which cannot be guranteed for seed obtained in the wild). Most hatcheries observe a closed cycle and rely on a original family of broodstock, this further reduces the need for capturing broodstock from the wild.
Critics of aquaculture raise the issue of aquaculture feed to prove that consuming farmed shrimp is bad for the environment. Shrimp require protein in their diet, and this protein in their diet comes from fishmeal. Keep in mind that fishmeal is used in a variety of animal feeds, so fishmeal that will not be used for shrimps will be consumed by chicken or some other animal (pork, beef, lamb). Shrimp and fish have a much better feed conversion ratios compared to chicken, pigs and other farmed animals. Also shrimp and fish require much less land, energy and water compared to other agricultural animals. So as far as the fishmeal argument goes, the greenest option would be to become a vegetarian, the next best thing would be fish/shrimp since they are making more optimal use of precious fishmeal and other resources. Simply avoiding aquaculture products will not reduce the demand for fishmeal, if anything more amount of fishmeal will be required if consumers substitute their protien intake from fish/shrimp to beef/poultry/pork. That aside the price of fishmeal continues to rise and there are efforts to look into alternatives such as Soya. Polyculture which is the practice of raising various shrimp/fish species together is a great model. The feed requirements are reduced and likelihood of diseases decreases too, however on the downside the yield per hectare is less.
Pollution is an issue that needs to be tackled. The claims about pollution range from the bizzare to the realistic. The bizzare claims are usually biased media stories that talk about “chemicals” being used in aquaculture, overall when I read such articles I am under the impression that farmed shrimp are radioactive franken shrimp mutants of some sort. Let me state clearly that producing such shrimp is biologically impossible, fish and shrimp are very sensitive creatures and any kind of chemicals that would be harmful for human consumption would destroy the crops. The realistic claims of pollution are about the excess of nitrogen and nitrogen waste that accumulate in these ponds. The amount of waste will be directly proportional to the stocking density of the pond. If the effluents from the ponds are untreated and released back into the nearby waterbody then it would result in eutriphication. The most cost effective way of treating them would be to have the effluent empty directly into a large reservoir, where the excess nitrogen will be gradually absrobed in the natural process. The advnatage of such a system is that it is also creating a large water body that usually supports a lot of other species and enhances the sorrounding eco system. In India such a system will be challenging since the cost of land is very high, apart from that government authorities need to ensure that the regulations laid down for responsible shrimp farming are being practiced. Better governance will result in a lot less environmental damage. Eco labels are a good initiative but they are not fully effective, however it is a step in the right direction.
Habitiat destruction is another issue that is raised against shrimp farming. Keeping India's federal structure in mind, it is not possible for firms and/or individuals to engages in destructive practices such as removing mangrove forests and converting the land into aquaculture farms. In other countries such as Thailand, Vietnam etc. The shrimp industry has a lot more clout, however in a large and diverse country such as India with effective and functioning institutions such as the Supreme Court of India and a pro active media and environmental groups, I would be suprised if large scale and systematic destruction of mangroves can take place. Currently you have supreme court orders and exisiting regulations that prevent such a scenario. Politicians would rather avoid being seen as supporting the shrimp industry. The negative image of the shrimp industry and aquaculture has ensured that politicians do not take up the development of this sector with a war footing. This has tragic consequences since sustainable aqauculture practices will boost the income of people living in coastal areas (their agricultural income will be limited due to saline soil). However with the help of the information revolution we hope that good sense will prevail.