Article by Kianna Gallagher.

“But do you still eat fish?” Aside from the scenario where I’m stranded on a desert island and only have meat as a food source, this question about our fishy friends is one of the most common questions regarding my diet. I decided long ago that given my stance on environmental issues a vegan or vegetarian diet was the way to go. It was always a bit puzzling; however, why fish did not seem to naturally fall into the category of ‘meat’ for a lot of people. They are animals after all!

I’ve considered many explanations for this. Perhaps it’s due to the very different habitat of fish in comparison to other farmed animals. When we think ‘meat’ we think of rusty red barns, bails of hay and wide-open prairies, not the vast blue ocean. Another possible explanation may lie in the notion that the oceans are plentiful and endless in the resources they can provide us. Or perhaps it is the fact that fish are often touted as a low carbon alternative to other sources of animal protein. While this is true, seafood comes with its own set of environmental problems that make it a less sustainable alternative. It’s important to understand these concerns in order to make informed choices about the kinds of seafood we eat, or whether we chose to eat seafood at all. Here are some of the main environmental concerns:

                

          1. Overfishing:

Over the years we’ve gotten extremely good at fishing. The size, power and capacity of fishing vessels have drastically increased. New technologies such as sonar, echo-sounders, and GPS have allowed us to target our effort more efficiently. Canning and freezing onboard ships have allowed for industrial vessels to remain at sea much longer than previously possible. On top of these technological advances, government subsidies have supported unsustainable fishing practices under the guise of economic growth. Unfortunately, these subsidies often result in a dog-chasing-its-own-tail type scenario. Subsidies are provided to support advances in fishing technology, higher efficiency practices result in higher catches and more food abundance, this abundance, in turn, drives down market prices resulting in more wasteful usage and lower profits for fishermen. Finally, this results in the need for greater efficiency and government subsidies for better fishing technologies. And the cycle repeats, all the while, the size of the fish population becomes smaller and smaller. In some places, this has lead to complete fishery collapse.

Despite these technological advances, government funds, and increased efficiency, world capture from fisheries has remained relatively constant since the mid-1980s (Figure 1). So despite the fact that our effort and efficiency have increased dramatically, we haven’t managed to increase the total catch. This trend indicates that the world’s fisheries have reached a limit.

According to the latest report on the State of World Fisheries and Aquaculture (2018) from the Food and Agriculture Organization of the United Nations (FAO), 33.1% of the world’s marine fish stocks are exploited at biologically unsustainable levels. This means that the rate at which we are catching fish from these stocks is greater than the rate at which they can be replaced by reproduction. This is, of course, the global average and some regions are under much greater stress. For example, according to the same report, 62.2% of fish stocks in the Mediterranean and the Black Sea are being fished at biologically unsustainable levels. The Southeast Pacific is not far behind at 61.5%, followed by the Southwest Atlantic at 58.8% (Figure 2). There is a clear need to lessen our impact on these fisheries.

          2. Destructive Fishing Methods and Bycatch:

Unfortunately, destructive fishing methods in some places are more the norm than the exception. These irresponsible fishing methods are leaving a hole in marine ecosystems. Replenishment by nature cannot match our rate of exploitation.

Two of the most common culprits include bottom trawling and long lining. Each comes with its own list of pros and cons. Bottom trawls scrape the seafloor of everything and anything in its path. They consist of a large net attached to heavyweights that drag along the seafloor. Bottom trawling is often used to catch animals that live on the seafloor such as shrimp, cod, rockfish, sole, and flounder. But this fishing method ends up ‘catching’ a whole lot more other stuff too. Habitat like coral reefs and soft-sediment ecosystems are swept away. The result is massive amounts of bycatch. Bycatch refers to all animals that are not the main target of a fishery. For example, if the target is sole, anything else that is caught will be considered bycatch and thrown back into the sea, likely dead or dying.

Longlines consist of a very long line, which can stretch for many miles with thousands of baited hooks. Longliners typically target big fish such as tuna, swordfish, and halibut. However, the hooks do not discriminate who takes a bite, leading to a staggering amount of bycatch; especially dolphins, sharks, sea turtles, and seabirds fall victim to the baited hooks.

          3. We are ‘fishing down the food chain’

It is well known that consuming animals high on the food chain is VERY inefficient. Only about 10% of the energy of one trophic level is transferred to the next. Imagine a simple marine food web such as the one illustrated below (Figure 3). Here the primary producers, phytoplankton (the plants of the sea) are eaten by tiny zooplankton who are in turn eaten by an intermediate predator like the bar jack. At the very top of the food chain is a top predator like the bluefin tuna. If the total primary production is 1000 kilos of phytoplankton, this translates to only 100 kilos of zooplankton. Humans, however, much prefer those animals higher on the food chain, like bluefin tuna. So in this same system, 1000 kilos of primary production would result in only 1 kilo of bluefin tuna.

These inefficiencies in the energy transfer between trophic levels mean the total number of top predators is always going to be much smaller than the number of primary producers. When it comes to fishing, we tend to exploit those species at the top of the food chain, like the bluefin tuna. Their populations quickly become reduced and overexploited due to fishing pressure. Eventually, we are not able to exploit these species to the extent we once did. We then move down the food chain, to species with a larger population, like the bar jack, until this species is overexploited as well. As top predators become increasingly sparse, entire marine food webs are altered, in turn putting the entire system at risk.

          4. Biomagnification

Not only is consuming so high up the food chain extremely inefficient, but it can be dangerous. This is because of biomagnification. Biomagnification occurs when animals at the bottom of the food chain, who contain pollutants in their bodies, are eaten by larger and larger things. As we move up the food chain these pollutants continue to accumulate. The pollutants present in one animal’s body are passed to the next and so on and so forth all the way to the top of the food chain. Animals at the top of the food chain, therefore, have the highest levels of pollutants in their bodies.

When we consume animals high on the food chain we are often exposed to dangerous levels of what is called, persistent organic pollutants (POPs). That’s just a fancy term for things that persist in the environment. We know many POPs are harmful to humans like mercury, DDT, and flame-retardants.

             

5. Some of the fish we eat are OLD

It is sad to consume something that might have been around long before you were born. For some long-lived fish species like the Orange Roughy, this is the unfortunate reality. Generally, long-lived species also reproduce much slower and have a higher risk of being overexploited. Moral concerns aside, the main problem with eating old fish goes back to biomagnification. The older the fish the more time it has had to accumulate harmful pollutants. On land, the animals we eat are months, or at most, maybe 1-2 years old. In contrast, the bluefin tuna in the example above take 10-14 years to even reach maturity. That’s a lot of years for toxins to accumulate.

What can you do about it?

Opting for a fish-free diet is a great way to lessen your impact on the oceans. Reducing the amount of fish in your diet is also a great place to start. Because of the environmental concerns listed above, we should treat fish, and other sources of animal protein, as a delicacy rather than something we consume regularly.

Pledge to go fish free for February!! If you follow us on Instagram or Facebook you know that the Odyssea team has committed to going fish-free this month. If you’d like to join us it’s not too late! Go to Fish Free February and sign the pledge!

We’ll be posting some resources and tips here and on our social media pages so give us a follow to stay in the loop!

About the author: Kianna is currently a master’s student studying global ocean change. She is from the very landlocked city of Edmonton, Canada but discovered her love of the oceans through diving. She has worked on various conservation and research projects including cetacean monitoring, coral conservation, and as a scientific divemaster.