Welcome back to our third segment on the four major types of Aquaculture! This one is for the folks out there who like to fish in the backyard. This month we’ll be talking about inshore-nearshore farms.
Inshore-nearshore farming overlaps with the cage culture we discussed last month. If you’re just joining us this month or need a quick reminder, cage culture is where (typically) mesh cages are placed in open bodies of water. It goes by many names, so you may have heard it called something else, (like net pen aquaculture, fish cage aquaculture, or open-net pens.)
So, how do cage culture and inshore-nearshore farming overlap? The enclosures used in modern cage culture can be the same as what are used in inshore-nearshore farms. However, the key difference is location. Like the name implies, inshore-nearshore farms are always along a coastline. This means that cage culture can be an inshore-nearshore farm off the coast but not all inshore-nearshore farms utilize cage culture.
Besides cage culture, another method of inshore-nearshore farming is a sort of “suspended aquaculture,” where the farmers will grow shellfish off the beaches by suspending them in the water using ropes, trays, or mesh bags. This method might also sound familiar to many of you…perhaps someone you know has an oyster cage or two hanging off their dock?
The suspended aquaculture method usually features filter-feeding water critters such as clams, scallops, mussels, and, most importantly for Maryland, oysters. This sort of suspension system is a very simple set-up which requires little care aside from clean water. As long as the species being farmed is native, this method also poses very little environmental risk.
Another very common Inshore-Nearshore method is pond aquaculture. The ponds in which fish are raised may be natural or man-made. The intention with a natural pond is that the fish will need very little interference from the farmer and will get some, if not all, of their nutrition from the natural environment. With this method, the number of fish the pond can hold is limited, though very stable. On the other hand, there is the potential for more space and flexibility with a manmade structure but it requires more human input.
The pond aquaculture branch of Inshore-Nearshore farming is particularly popular in Asian countries, as it is often used in conjunction with rice farming. Rice paddy fields must be flooded with water to thrive, and farmers may either artificially stock the flooded fields or open channels to let in wildlife. This method is both ecologically and economically harmonious; good for the earth and for the farmer’s wallet. Scientists have found that rice yields are up to 12% higher in fields that had aquatic life. Fish enrich the soil with their waste, thus reducing the need for fertilizers, and eat many of the pests that can decimate rice.
While the particular benefits and challenges of inshore-nearshore farming can vary with different culture methods, there are a few constants based on the nature of being inshore. First, being near the coast means you can keep a close eye on any changes to your farm and respond much quicker than if you had your cages placed further out at sea (which is what we’ll be talking about next month so keep an eye out!)
Secondly, the nearness of an inshore-nearshore farm allows the option to create ecosystem-based aquaculture. This idea combines fish aquaculture with seaweed and other shellfish which creates a localized mini-ecosystem within the larger, natural ecosystem of the shoreline. This mini-ecosystem can help naturally address a lot of problems aquaculture faces, such as excess waste. The shellfish filter the water and the seaweed absorb the excess nutrients from the fish waste, which helps minimize algal blooms and dead zones which we might see from single organism aquaculture systems. While this type of setup is good in theory, real world examples are few and far between, though several companies are utilizing this concept for recirculating aquaculture systems. Using indoor systems, farmers are growing plants hydroponically and growing fish such as catfish in the connected water tanks. The catfish waste then fertilizes the plants and farmers are able to produce two marketable products; catfish and produce like fresh herbs and greens.
That’s all for this month! See you in April for the final quarter where the newsletter topic will be heading out into the wide open waters.