Fishing: a billion-dollar industry that is on the fast track to causing ecosystem collapse. Humans and animals across the world rely on fish as an important protein source, but about 90% of fish populations are fished at, or above, their sustainable limits. In 2021 approximately 8.5 billion pounds of fish were caught in the United States alone.
If things continue per the status quo, these fish, and the people and animals who rely on them, won’t have a future. Just like with animal agriculture, the fishing industry has surprising overarching effects. Let’s dive in and continue the conversation about the impacts of our food choices.
What is sustainable fishing?
The idea of sustainability implies the use of a resource without depleting it, thus ensuring future use. So, sustainable fishing must be fishing in a way that doesn’t destroy the populations of fish. Enough fish must be left so they can reproduce and maintain the numbers necessary to survive while simultaneously being used as a resource.
Currently, there aren’t rigid rules defining what “sustainable fishing” is due to a myriad of factors that come into play. This includes varying harvest limits and catch numbers, changes in the ecosystem due to habitat degradation, the types of fishing gear used, and varying fishing seasons for each fish. The concept of sustainable fishing remains the same though, we need to use the resource in a way that still leaves enough fish in the wild to sustain the ecosystem.
So, what’s the catch?
Although the goal of creating a sustainable fishing sector is admirable, it’s by no means a perfect practice. Current economic and political systems do not allow for the sustainable management of the fishing industry. We are managing fish populations under uncertain conditions while also trying to increase harvests to meet rising demands. Sustainable fishing as it stands is a broken concept. Therefore, even if a fishery is described as sustainable that doesn’t mean it is.
The focus of sustainable fisheries typically falls on maximum sustainable yield allowances to determine the number of fish that can be harvested while allowing the populations to persist. But these allowances do not consider the overarching sustainability of the ecosystems these fish populations are a part of. With climate change also changing the distribution of populations and introducing new variables that must be accounted for, it’s hard to get an accurate yield estimation. Maximum sustainable yield allowances are also determined by population size, yet it is extremely difficult to find true population numbers in the ocean. We must account for potential errors to ensure populations remain intact. Unfortunately, this does not happen. More variables need to be considered and the true exploitation of these fish needs to be understood.
When fish, or any aquatic wildlife, are harvested at a rate beyond their sustainable limits they can be classified as overfished. Fishers remove more than 170 billion pounds of wildlife every year. With current fishing techniques, many fish can be caught at a time and while that may be amazing for industry, it leaves few fish in the ocean.
Overfishing affects the fish being targeted and the overall ecosystem.
Fishing inherently has direct and indirect effects on the ecosystem. Direct effects are those that occur specifically from an action while indirect effects are those that are byproducts of an action.
A direct effect of the fishing industry is that about 8% of global primary production in the sea is removed. The ocean plays a huge role in absorbing CO2, and by changing the ocean’s capacity to perform that ecosystem service by influencing productivity the stability of our environment is lessened. Due to this, we can expect an acceleration of climate change and ocean acidification.
Furthermore, another direct effect of fishing is bycatch, aka catching and consequently killing species that were not the intended catch. Other animals get caught in fishing nets and lines and become waste. Every year about 40% of fish caught worldwide are discarded as bycatch. Bycatch is one of the biggest issues in the fishing industry and it occurs with virtually all fishing despite efforts to quell it. Animals such as sea turtles, marine mammals (like seals, dolphins, and whales), seabirds, benthic animals (like corals, anemones, and sea stars), and unintended fish (like swordfish and sharks) are all affected.
Bycatch has led to extinction worries for many species.
The indirect effects of fishing can be even more profound though. Many aquatic ecosystems have been substantially altered due to the fishing industry. For example, a fishing practice known as dredging destroys the seafloor. The destruction of this important habitat has contributed to the destruction of coral reefs, seagrasses, and oyster reefs which has greater repercussions for the entire ecosystem.
The fishing industry has also indirectly altered food web interactions through the removal of key species. For instance, the overfishing of herbivorous fishes has caused macroalgae to overgrow and kill corals. Predators like seabirds and marine mammals can also lose their source of food. The removal of key predators, like tuna, can also increase the population sizes of their prey and have further implications. Genetic diversity is also affected, fishermen want large fish and this makes it so that only small fish reproduce. This then changes the overall sizes of the fish and has further implications for species interactions.
Fishing changes the structure of marine communities and harms the ecosystem which has trickle-down effects for the entire environment.
What about fish farming though?
Fish farms, also known broadly as aquaculture, also have many issues despite the perception that aquaculture eases the pressure off wild populations. When on a smaller scale, fish farms can be a more sustainable option, but the increasing numbers of farms and the growing intensity of aquaculture have caused environmental damage that can’t be ignored.
Most species used for aquaculture are essentially wild but some have been selectively bred. This means fish that have certain traits are chosen to reproduce and their offspring are used for the new generations on the farm. The traits typically selected are things such as faster growth and earlier maturation so you get bigger fish in a shorter time. Some species have also been modified so they produce infertile individuals after breeding. While this is ideal for the industry it’s not ideal for the environment.
Farmed fish have been known to escape and negatively affect wild populations. There is always a risk of potential competition for resources between native and cultured species. There is also the potential to create permanent infertility when a farmed fish mates with a wild one. Diseases also spread quickly in fish farms. So, escaping fish can spread disease to wild fish which can decimate wild populations. This then leads to biodiversity issues.
Feed, the food farmed fish are given, ingredients also have an impact on the environment. Fish feed contributes to land use issues and overfishing depending on what the fishery decides to feed the fish. Fishmeal and soybean flour, which are some of the most common types of feed, have profound impacts on the environment. Fishmeal increases the impact of the fishing industry on the environment because you need to catch or raise more fish just to feed other fish. Fishmeal is a limited resource though because of how overfished most fish populations are. Using plant feed is a better option than fishmeal however land use issues then come into play.
Fish farming also produces a lot of waste. Although fish waste is a natural byproduct, the high concentrations of waste pollute surrounding waters which can then create algal blooms. Algal blooms are concentrated algae growths that not only create toxins that are harmful to the animals that encounter them but can also create a lack of oxygen which can impact the entire ecosystem. The resulting decline in water quality due to this pollution creates widespread fish kills. Poor water quality can also lead to poor fish growth and a decrease in production for the farms too.
Is there any solution?
There is so much more to creating a sustainable fishing industry than just adjusting numbers and producing our own fish stocks. But, simply put, overfishing reduces fishery outputs. So, as things stand right now, the fishing industry is unsustainable. The oceans and fish are resources that so many rely on, however, the use of a resource is a privilege, not a right.
We must understand that fish play an important role in healthy marine ecosystems that goes beyond just thinking about maximum sustainable yield. Poor fishing practices exacerbate climate change. We must balance the drive for profit, the need for food provision, and conservation goals.
Researchers have proposed things such as taxing overfished species, limiting the operation of fishing vessels, or switching subsidies to sustainable activities like promoting “fishing for plastic”. Reimagining the fishing industry would help local communities while also increasing ecosystem functioning to ensure a resilient marine ecosystem.
Research also shows that permanent changes to the ecosystem can be prevented if overharvest is addressed. So, the best way to address the issues associated with the fishing industry is to stop eating fish and other seafood. Dr. Sylvia Earle, a marine biologist and conservationist, told National Geographic: “I personally have stopped eating seafood, I know too much. I know that every fish counts at this point. Some more than others, but I can no longer bear the thought of eating tuna knowing in what dire straits they currently are. If we value the ocean and the ocean’s health at all, we have to understand that fish are critical to maintaining the integrity of ocean systems, which in turn make the planet work.”.
Consumers must be mindful. We must minimize the exploitation of our oceans. The animals that live in the oceans are co-inhabitants of our world, not our commodities.