Week 6: Is Seafood Eco-friendly?


People find it hardest to sympathise with fish, crabs, lobsters, prawns, and octopus because they look so different from us. They aren’t cuddly, seen as “cute”, and lack the facial expressions we use to determine emotions. They also breathe underwater, making them even more obscure to us. We also have been led to believe that they have low intelligence and cannot feel pain. For this reason, we often do not think of them as a living being who is worthy of protection. This notion has created a huge problem for fish, in terms of the way we treat them, catch, and breed them for food. 

What is also interesting, is how we place different values on sea creatures, wanting to protect whales, dolphins, turtles, and seals, all while supporting the massacre of up to 3 trillion tuna, prawns, salmon, lobsters, crabs, and octopus, to name a few.

sea creatures whales and tuna

This week, we will be learning about sea creatures ability to feel pain and their sentience, how the industry operates, the environmental damage caused by our desire to eat fish, and the health implications of consuming seafood.

About Sea Creatures

Despite popular belief, scientists have proven time and time again that fish do feel pain and actually have complex thoughts, making them sentient creatures just like cows, dogs, and humans. More emerging evidence suggests that despite how different we look from one another, a fish brain is more similar to humans than we thought [1].

Sea creatures feel pain.

“There is as much evidence that fish feel pain and suffer as there is for birds and mammals. I see no logical reason why we should not extend to fish the same welfare considerations that we currently extend to birds and mammals”.  

Victoria Braithwaite, biologist and researcher, “Do Fish Feel Pain?”


Biologist and researcher, Victoria Braithwaite, found that fish have specialized receptors (nociceptors) on their head and body. These receptors respond to weak acid, hot temperatures, and crushing of the skin – and allow them to respond and protect themselves [2]. Fish, in the study, were given a mild electric shock to their tail, and their response was recorded in several areas of the brain. This neurological response shows that they are capable of feeling fear and are motivated by the understanding of pain.

Another study accessed the behaviour of fish after they were injected with bee venom or vinegar around their mouths. All fish reduced their eating, had increased breathing rates, and rubbed the injection site against the tank to relieve the pain. The fish in this study also changed their behaviour when in pain, showing that the pain affected their mental state and not just their physiology. After pain-relief was given, fish returned to normal behaviour [3]

Other studies showed that fish are willing to pay a cost to avoid pain. Zebrafish had access to two tanks, one completely barren, and one with enrichment. Unsurprisingly, all zebrafish chose the enriched tank. The fish were then injected with a painful acid, and the barren tank contained pain-numbing anaesthetic. The fish assessed their choices, and all chose to stay in the barren tank, to relieve themselves of the pain [4]. This shows that the zebrafish changed their behaviour to avoid pain.

It isn’t that fish just feel pain, they also remember it and learn to avoid it. Fish who were exposed to painful stimulus later showed signs of fear and wariness. This finding is important as it highlights the fact that avoidance is not a reflex response, but is learned, remembered, and modified.

Crustaceans and Octopuses

Hermit crabs were given small electric shocks, to test whether they would leave their shell and search for a new one – and they did [5]. It was concluded that “crabs trade-off their need for a quality shell, with the need to avoid the harmful stimulus” [6].

Studies on prawns have shown that they rub the area where they experienced pain. Once pain relief was given, the rubbing reduced [7]

Octopuses have a central nervous system – like us, however, it seems less-central than ours. For example, each arm appears to act freely, however, is operated by the octopus’ bi-cephalic brain. They do feel pain, despite being known to amputate their arms, if it is necessary for their survival, like escaping a predator. This act shows that they have high complex thinking as they assess the situation and respond appropriately. Studies found that all octopuses tended to and guarded their injuries for some time – an indicator of pain [8]. After receiving pain relief, the octopuses changed their body colour, had slower breathing, and less suction with substance [8].

We would like to note that Animal Liberation is against all testing on animals and are disturbed by the tests that have been done to these sentient beings.

Sea creatures are sentient.

To be sentient is to have the capacity to feel, perceive, or experience subjectively – and sea creatures definitely do. Sentience is difficult to measure in other species. For this reason, experiments test for consciousness, their attention and perception, self-recognition, theory of mind, and episodic memory. They then conclude that if an animal is conscious they are likely to be sentient [1]


Research on fish has shown that their cognitive abilities often match or exceed other vertebrates and their behaviours exhibit consciousness, are self-aware, and thus are sentient [1]!

Fish have proven to have excellent memories, they also live in complex social communities, keep track of individuals, learn from one another, and recognise themselves and others. These elements allowed scientists to conclude that fish are even able to develop stable cultural traditions! They also use cooperation and reconciliation, a sign of Machiavellian intelligence. Some species build complex structures and can use tools. When comparing their behaviours to primates, there were very few differences [1].

Fish were found to communicate with each other using squeaks and other low-frequency sounds that are outside of the human hearing range [9], as well as “sign language” or “Morse code.” For example, lionfish wave the row of fins on their backs in a certain way to signal other fish to join them in a hunt [10]. Large groupers are known to alert moray eels to hunt fish concealed in a crevice by shimmying their bodies and pointing their noses towards where the fish is hiding [11]. Fish can think critically and perform complex behaviours to solve daily problems. They also enjoy physical contact with other fish and will often rub against one another.


Octopi are among the most intelligent invertebrates around. They are known to use tools, carry shelters around for when they need it, and, even, adopt an underwater walking motion that’s very similar to humans [12]! Octopuses, both male and female, frequently communicate with each other in challenging displays that include “posturing and changing colour”. If octopuses displayed dark colours, the encounter would be aggressive, versus paler colours, which indicate retreat [13]. Some species have been found to live in groups of up to possibly 40, laying multiple egg clutches, and mating face-to-face – something that is incredibly rare [14].

The Industry

The seafood industry equates the number of lives killed in tonnes, rather than an actual number. It is estimated, however, that humans kill between 1-3 trillion animals every year [15]. To meet our collective demands, the industry uses trawlers, longlines, and aquafarms. All of which are causing irreversible damage to the ocean and the world as we know it.  


Trawling is one of the most common methods of fishing. It involves towing huge nets – sometimes the size of a football field – behind a boat either through the middle of the ocean or along the seafloor [16]. This method captures every single animal unlucky enough to swim in its path. These boats haul up tens of thousands of fish in a single load. Trawling is basically the underwater equivalent of clear-cutting forests. Our demand for seafood is emptying the oceans at an alarming pace and wasting all our precious sea life. 

Prawn trawlers can tow between 1 to 4 nets at a time. They are designed to skim the seabed and encourage prawns to enter the trawl mouth. These nets have smaller mesh – meaning it is harder for other animals to escape [17].

trawler fishing net overfishing
A trawler fishing net full of individuals.


There are three types of longlines – pelagic, bottom, and automatic. Pelagic involves setting up a line that is many kilometres long with thousands of hooks (sometimes 10,000!) attached to mini lines, called “snoods”. They are designed to catch tuna and billfish species. Bottom longline involves setting up long lines with hooks along the seafloor, to catch gummy sharks, saw sharks, and elephant fish. Automatic longlines involve placing a line with hooks along the seafloor and bringing it up every 6-8 hours [18].

Being caught on a longline is incredibly traumatic for the animals, as they can be there for hours or even days at a time. Most fish caught on pelagic lines are dead by the time they reach the boat [19]. As proven earlier, fish feel pain and being caught by their mouth with a hook is unethical. It also leaves them susceptible to predators, as they are unable to escape.

longline fishing
Example of a longline.

Fish and Crustacean Farms

To cater to our ever-increasing demand for seafood, fish and crustacean farms are increasing. We are now breeding, raising, and mass-producing sea creatures in artificial environments so they can be sold as food. Approximately 44% of total global fish production comes from aquaculture [20]. These factory farming systems are built to maximize production and minimize costs.

seafood fish farm
An ocean fish farm.

Farmed fish spend their entire lives in crowded and filthy enclosures. These farms can be as big as ten football fields put together and often contain more than 1 million fish [21]. They spend every single minute of their life unable to move freely, only to suffer a long and painful death.

seafood fish farm
An inland fish farm in Australia.

When the fish become most “profitable”, they are either killed by asphyxiation (suffocation by taking them out of water), which can take up to several hours, are exposed to carbon dioxide or very low temperatures, or are bled out [22]. All causing immense pain and suffering.

These fish never even get to swim freely in the ocean, their home. The cramped enclosures they live in, inhibit their ability to move and cause them to knock against each other. As a result, many fish suffer from parasitic infections, blindness, deafness, diseases, severe injuries, and even depression [23, 24]. In 2016, researchers examined the brains of sluggish, stunted salmon on farms, and found sky-high measures of the stress hormone cortisol. Their serotonin levels mirroring those of depressed mammal [25]. These aquatic animals are treated like biological machines when they are only innocent sentient beings who just want to live. 

deformed seafood fish farm
Still from an exposé regarding farmed salmon in Canada.
Credit: CBC News


Most species of farmed fish and crustaceans are carnivorous, which means that additional fish must be caught from our already-exhausted oceans to feed them. This makes aquafarming immensely unsustainable. It is estimated that 37% of all global seafood is now ground into fish feed [26]

In an article on bluefin tuna farming published in the San Francisco Chronicle, a seafood wholesaler estimated that it takes 57.3 kilograms (26 pounds) of fish from the ocean to produce 1 kilogram (1 pound) of farmed bluefin tuna [27]! Every kilogram of salmon or prawns can use up 2.5-5 kg of wild fish as feed throughout its life [28]. Aquafarmers are even feeding fish oil and fish meal to herbivorous fish (who are only supposed to eat plants) to make them grow faster and be more profitable [29]. Additionally, farmed fish can be fed ground-up animals from other farms, mixed with fish caught from trawlers! Cows, chickens, pigs, ducks, and lamb, is an unnatural food source for fish, and can have a potential impact on them. As we mentioned in our blog Are chickens really meant for eating?”, animal by-products are collected and rendered into animal feed.

fishing net seafood

Antibiotics and Drugs

Disease outbreaks are common in aquaculture, due to a wide range of pathogens (viruses, bacteria, parasites), and husbandry factors, like overcrowding, water quality [30]. Although Australia has some restrictions on the use of antibiotics, other countries do not. For this reason, aquafarmers combine fish feed with chemicals and antibiotics to help the fish survive the deadly diseases from their environment [31]. Genetic engineering is also used to accelerate growth, and hormones are being injected into fish to change their reproductive behaviour [32]

The Environment

Both commercial fishing and fish farms are killing the planet. The major environmental impacts are overfishing, by-catch, pollution, and introduced species. 


At last count in 2014, 80% of commercial fish stocks were declared fully exploited or overexploited [33]. Almost 31% of the world’s fish populations are overfished, and another 58% are fished at the maximum sustainable level [34]. Fish simply cannot reproduce as fast as 7.8 billion people can eat them. We are now at a biological limit.

Nearly one-third of all fish species have declined in population in the last 15 years [35]. It is predicted, that if fishing rates continue, all the world’s fisheries will collapse by the year 2048 [36]. This means we are going to have fishless oceans before the middle of the century – and without fish, the oceans die, and ultimately the planet too.

overfishing seafood
Fishing net being emptied on the boat.


Trawlers and longlines both result in by-catch, where non-target species, such as dolphins, whales, sea turtles, rays, seabirds, crabs, and sharks, are caught, trapped, hooked, or become entangled [37]. It also includes young fish that could rebuild populations if they were left to breed [38]. According to global estimates, around 38 million tonnes of unwanted sea life are caught, making up 40% of the world’s catch [39,40]! For every kilogram of fish caught, there is up to 2.3 kilograms of non-target species, and for every 1 kilogram of prawns, there is around 5 to 20 kilograms of bycatch in the nets [41]. OCEANA estimated that 150 turtles are captured per day and more than 100 million sharks every year [42]. This means that our collective demand for seafood kills millions of the aquatic animals that we believe deserve protection. 

Although there are management strategies in place to “reduce” by-catch, many rely on workers returning these “unwanted” animals to the ocean, but this does not guarantee their survival. Most are already dead, dying by the time they are found, and the stress and injury from being caught can impact their survival once they are returned [43].

To add insult to injury, trawling is largely responsible for diminishing the most valuable sea creature, phytoplankton. Phytoplankton are responsible for producing 80% of the world’s oxygen – this means, most of the oxygen we breath is from the ocean! According to Watson, the founder of the Shepherd Conservation Society, “Since 1950, there’s been a diminishment by 40% of all the phytoplankton in all the world’s oceans… If we lose phytoplankton, we don’t survive” [44]. Dragging nets across the seafloor not only destroys habitats like coral reefs but stirs up the sediment lying on the seabed. This causes pollutants to mix into phytoplankton, resulting in the formation of harmful algal blooms and oxygen-deficient dead zones. This endangers food webs and ocean ecosystems by disrupting the balance of all sea life [45]

seafood with bycatch overfishing
Dead shark on fishing trawler.


Both commercial fishing and aquafarming pose an existential threat to our planet. They are exacerbating the overfishing problem by joining forces with our number one enemy, pollution. Commercial fishing is responsible for most of the great ocean garbage patch, due to lost or purposefully discarded fishing nets accounting for 46% of the trash, and the rest being ropes, oyster spacers, eel traps, crates, lines, and baskets [46]. Discarded fishing equipment is responsible for around 30% of the decline in some fish populations, and more than 70% of marine animal entanglements involve abandoned plastic fishing nets [47].

turtle stuck in fishing net
Turtle caught in discarded fishing net.

Aquafarms are responsible for chemical pollutants, like excess nutrients and contaminants, in the ocean that is mixing with our precious phytoplankton [48]! Nitrogen is a vital nutrient for aquatic organisms like phytoplankton. The sewage and fertiliser that comes from fish farms, however, results in too much nitrogen. This stimulates algal blooms. When the algae dies in the water, microbes that break it down use up lots of oxygen. They create dead zones in the ocean that suffocate fish and other aquatic animals [49]. This is how oceans die. Contaminants from ocean-based aquafarms, such as vaccines, fertilisers, disinfectants, pesticides, fish excrement, uneaten chemical-laden food, and swarms of parasites, spread to the surrounding ocean. This works to poison our dying oceans even more. The diseases inside the enclosures are passed on to free-swimming fish in the area, threatening fish populations to the point of extinction.

A 2-acre salmon farm produces as much waste as a town of 10,000 people [50]. Salmon farms in British Columbia were found to be producing as much waste as a city of half a million people. According to PETA, raising 1 ton of fish takes 8 tons of water. Intensive shrimp production takes up to 10 times more water [51].

pollution fish farm
How ocean fish farms pollute the ocean.
Credit: Dr. George Pararas Carayannis

Introduced Species

Another way aquaculture negatively impacts the environment is by introducing farmed species into the wild and changing the biodiversity of marine ecosystems. This occurred in the UK in the 1960’s, when the Pacific oyster was introduced into their waters. These oysters spread and created reef formations, forcing out the native oysters and completely changing the marine environment [52]. It’s not just fish farming that is destroying the environment. Various studies have been published which delve into the environmental impacts of shrimp farming as well [53]

Farmed fish are selectively breed and they consequently have a lower genetic variation than wild fish. When they escape into the wild and interbreed with wild fish, this causes the formation of a less genetically diverse population. It can even result in infertile offspring, which definitely doesn’t help the overfishing problem. This poses an existential threat to many fish species because a less robust population is prone to environmental pressures such as disease and natural disasters [54]


Your health

You fish fillet has plastic in it. The truth is, microplastics inhabit every corner of the planet, from our beaches to Arctic sea ice, from farm fields to urban air [55]. They are being consumed by the fish and accumulate up the food chain, ending up on our plates. Just because you can’t see them, doesn’t mean they aren’t there. Microplastics can be microscopic. These tiny pieces are leaving the gut of the fish and entering their muscles! Studies detected plastic in all fish muscle samples [56]. But the issue doesn’t stop there. Microplastics can also enter the bloodstream, and result in clots [55]. Although scientists aren’t entirely sure what the overall impacts will be on humans, they have found that “not only did fish exposed to microplastics reproduce less but their offspring, who weren’t directly exposed to plastic particles, also had fewer young, suggesting the effects can linger into subsequent generations” [55]

On top of ingesting plastic, the plastic particles can also release absorbed pollutants, like PCB’s, and chemical additives like BPA, which can increase risks of cancers, cause hormone disruption, and DNA damage. There is no standard dose for ingesting microplastics, as there is currently a lack of information regarding toxicity levels, however, it was concluded that it will have an impact on human health, especially children and pregnant women [56]. A study of more than 12,000 food and feed samples, across 18 countries found that the highest PCB contamination was found in fish and fish oil, followed by eggs, dairy, and then other meats. The lowest contamination was found at the bottom of the food chain, in plants [57].

ocean garbage patch

Hexachlorobenzene, another pesticide banned nearly a half-century ago, today may be found mainly in dairy and meat, including fish. Perfluorochemicals, also known as PFCs, are overwhelmingly found in fish and other meats. The contaminants in fish may help explain studies showing an association between fish consumption and diabetes [57, 58].

Ultimately, to lower our exposure to pollutants, we should try to eat as low on the food chain as possible. If you’re concerned about consuming enough omega-3, see what plant-based foods contain it, here.

Public Health

The use of antibiotics used in aquaculture could spread drug resistance from animal to human pathogens [59]. The use of chemicals and antibiotics also results in dangerously high levels of PCB and dioxin in farmed fish. These toxins pose serious health risks to people who eat seafood. 

What’s Next?

We are taught that our straws and plastic bottles are killing sea creatures, which is true, but our diet is having a far greater impact. From an ethical, environmental, and health perspective, leaving sea creatures off of our plates is the way forward. It is evident that these weird and wonderful creatures have a purpose far greater than becoming a five-minute meal. 

We are now in the middle of the largest mass extinction of species in 65 million years – and we need sea creatures if we want to survive. If we allow fishing rates to continue, the loss of biodiversity and phytoplankton populations in the sea will cause the collapse of the oceans, leading to the possible extinction of the human species. This might sound crazy, but it’s true. But it isn’t too late. If we demand fewer seafood products, then fewer sea creatures will be captured and populations can begin to thrive. This will restore balance to the ocean by saving up to 3 trillion individuals, as well as the turtles, sharks, and whales. 

To help you transition away from seafood, try one of these fish-free meals today! Remember, veganism isn’t about giving up anything. It’s about refusing to participate in the exploitation of the planet and its inhabitants. Your demand for alternatives will help plant-based foods become cheaper, more sustainable, and more readily available!