Just like everything else in our lives, the seafood industry is subject to a wide amount of scrutiny when it comes to sustainability and eco-friendly practices.
We eat a lot of seafood in the United States, and with that comes an intense focus on farming and wild-catching practices that fishers use to meet the high demand. Wild-catch fishing, for example, has a host of pros and cons that change depending on the species being caught, the methods used to catch them and the areas being fished.
Let’s take a look into another important part of the fishing industry here in the United States that delivers our favorite seafood to us — a process known as aquaculture.
All you need to know about farm-grown fish
What is aquaculture?
We’ve already talked about wild-catch fishing and how it is an important piece of the fishing industry, so now let’s dive into the more controlled conditions of farm fishing, also known as hatchery fishing or aquaculture.
At its simplest, aquaculture is the process of breeding and rearing marine organisms in controlled environments. This includes growing fish and shellfish for consumption, but it can also extend as far as growing algae and seaweed for research purposes, or rearing rare fish to replenish dwindling populations. Essentially, it’s like having a farm underwater that can be used for many different purposes.
Here, we’ll focus on the more commercial side of aquaculture that’s utilized for the seafood industry.
Aquaculture is usually done by building net pens in the natural water environment (i.e. lakes, rivers, oceans etc.) or by building tanks on land. Onshore aquaculture tanks can vary in size and shape, with tanks ranging from a few meters in diameter to tanks the size of small ponds. Some tanks are round, some are built in long channels and some are in a racetrack-like loop. The sizes all depend on the type of fish being hatched or reared, as a tank that’s too small can cause stress to the fish inside.
Net pens in natural water environments are floating cages that allow the natural water to move through the pen while still containing the fish being farmed inside. There are typically two layers of cage on these pens: the first is a loose net that keeps the fish inside the pen, and the second is a solid, exterior cage that keeps any natural predators out. Fish farmers can collect any number of pens and tie them together for easy access and maintenance.
Aquaculture also includes farming for shellfish like clams, oysters, mussels and shrimp. It’s far easier to farm these marine organisms than it is to catch them in the wild, so a fair bit of aquaculture is dedicated to farming shellfish.
The techniques for farming shellfish vary depending on the species. Most shellfish grow on lines or logs suspended in the water above the sediments, as well as on grow bags on the water bottom or just straight on the beach! Canals, bays and estuaries provide the best locations for farming shellfish because of the easy access and tidal activity that the marine creatures are naturally drawn to.
What are the cons of hatchery-grown fish?
Aquaculture isn’t inherently good or bad, but it's certainly not suited to every marine species.
When it comes to farming fish, there are a lot of factors to consider. Fish rely on seaweed and smaller fish to eat and sustain themselves, and net pens and tanks do not provide enough of that naturally. This means farmers have to feed those fish using other farmed fish or wild-caught fish, which seems to defeat the point of farming for fish in the first place.
Fish farms can also affect the natural environment around them, especially if the farm is in a natural water source such as a lake, ocean or bay. If a non-native fish from a farm escapes, how would that impact the local ecosystem? If that fish becomes an invasive species, what other species are caught up in the collateral damage? Even the high concentration of waste, feed and chemicals that exist around the farms can seep into the natural habitats around them.
Large, shallow coastal ponds used to grow shrimp are highly damaging to fragile coastal ecosystems, as they strip away any natural habitats and flood the land with saltwater. These ponds can be used in sustainable ways, but their negative impacts against the natural environment are fairly significant.
What are pros to farm-grown fish?
Despite all the doom and gloom, there are absolutely ways to sustainably farm fish and shellfish in ways that can protect the environment and not use up too many resources.
Oysters and clams, for example, will grow at the same rate without much direct human intervention, whether they’re in a farm or not. They filter the water around them and eat the natural particles floating around, so there is no need to add feed, collect waste or keep them from moving around. They require very little — if any — maintenance before they are harvested, making them ideal species for aquaculture.
Some species like tilapia and catfish are well-suited to aquaculture farms, as they are not picky about what they eat and can be grown in many areas.
Land-based aquaculture farms cause very little damage to the environment, granted there is a good filtration system in place. Recirculating tanks allow for the fish’s environments to be constantly cleaned and refreshed, keeping the fish healthy and the waste properly managed. The risk of an invasive escapee is nonexistent and it’s easy to control how and when the fish are harvested.
So, what do we do?
When it comes to finding sustainable methods of fish farming, it all comes down to the product itself. Each farm is different and each fish or shellfish species has a different role to play, so take it one fish at a time if you’re looking to make sustainable swaps.
Learn about local fish farms to see what their practices are, or do research on a specific brand that aligns with sustainable practices. Buy fish or shellfish that are well-suited to fish farms and that have the least impact on the natural habitat. Finally, use resources like Seafood Watch, the Aquaculture Stewardship Council, Friend of the Sea and the Global Seafood Alliance to learn more about the ever-changing world of aquaculture.
Enjoy, and good luck!
Featured photo courtesy Pixabay/LTapsaH