How does it impact fish? 

Aquaculture operations are built on the premise that fish do not feel pain and the current production rate leaves little room for the ethical treatment of fish. To reduce costs, fish are only seldom stunned (=desensitized) before slaughter, kept in poor conditions (e.g. low water quality, starvation, overcrowding) and are frequently handled out of water (Ashley, 2007). This leads to disease outbreaks, injuries and aggression between individuals. As a result mortality rates on aquaculture farms are high, ranging from 25 to 50% from hatching until fish are grown (Undercurrentnews, 2018). Unfortunately, wild-caught fish cannot expect more humane treatment. With little oversight of fishing activities, many wild-caught fish are dying painfully. When being lifted with a net, lower-lying fish get crushed to death and remaining ones are left to suffocate onboard the ship. Animal Equality has recorded painful procedures for catching tuna which leaves them suffering for many hours while workers stab them.

How does aquaculture impact the ocean & environment? 

Ever seen a fish swim underneath your board while you were sitting in the line-up waiting for your next ride? You may be surprised to learn that even these wild fish are negatively affected by common aquaculture practice. Fish meal, which is used to feed carnivorous farmed fish (such as Atlantic salmon and rainbow trout), contributes a great deal to overfishing, depleting ocean fish stocks and causing problems along the whole food chain which threaten the well-being of our oceans (Naylor, 2005). In the last two decades, ⅓ of wild-caught fish worldwide has been used for fish meal production. This means 6-7 million metric tons per year (Banrie, 2012). In Mauritania, one of the major fish meal producing countries, up to 50% of wild-caught fish are used for fish meal production of which generally 5kg fish give 1kg of fish meal (Changing Markets Foundation, 2019).

Disease spread is a major concern in mariculture (ocean-based aquaculture operations). Scientists are even concerned that fish on inland aquaculture farms could spread diseases to other animals, for example birds (Naylor, 2005). In mariculture, wild fish are attracted close to the cage where farmed fish are kept by feed. This is often enough for a pathogen (disease-causing organism) to spread from farmed to wild individuals and vice versa.

Finally, aquaculture produces wastewater which is released back into the environment. If this water does not get filtered, it contaminates local rivers and nature, eventually draining to the very ocean you dipped your head in this morning. Particularly in mariculture, where filtration is not possible because cages are in the ocean without any barriers, waste can easily diffuse (Gormaz, 2014).

Should I eat fish? 

Now here comes the million-dollar question: With fish feeling pain and aquaculture offering great potential for suffering, should we even continue eating fish? The answer to this question is a personal decision, though I would like to highlight some thoughts you may want to consider when making this decision: 

From an animal rights perspective, eating fish today is hard to defend ethically. Certification schemes are only doing first steps to include welfare standards and many fish suffer greatly, particularly in Asia where 90% of seafood consumed comes from (Bondando-Reantaso, 2005). 

“[T]he general agreement is that current aquaculture practices are neither meeting the needs of fish nor environment. Thus, the obvious environmental and animal welfare aspects of finfish aquaculture make it hard to ethically defend a fish diet.” (Bergqvist & Gunnarsson, 2011)

Further reads

Books

“Do fish feel pain?”, Victoria Braithwaite

“What a fish knows?”, Jonathan Balcombe

Blog posts

“Do fish feel pain?”, Fish Welfare Initiative

“Pain of the fish”, La Fondation Droit Animal

Other

Compassion in World Farming Fish Welfare

Aquatic Life Institute for top-down approach to this problem