The Scallop Biofouling Problem
In the last 20 or so years, scallop aquaculture has gained a foothold in the scallop market. While there is currently a healthy wild scallop fishery in the Gulf of Maine, scallop aquaculture has the potential to occupy a niche for small “petit” scallops, large “jumbo” scallops, or selling the entire scallop, not just the adductor muscle.
One of the major barriers to farming scallops efficiently is dealing with biofouling. Managing the build-up of marine growth on lantern nets – which are often used to contain scallops while they grow – is difficult and labor-intensive. The most common cleaning methods include pressure washing, air drying, and hot water dipping, all of which are either expensive or take a long time. Through a collaboration between Ocean Farm Supply and the Hurricane Island Center for Science and Leadership, researchers are developing a single-use compostable cover that could be used to mitigate biofouling on scallop gear.
One of the popular methods for scallop cultivation in the Gulf of Maine is to use lantern nets. These are cylindrical nets that house multiple different enclosed sections. Scallops are placed into the sections of the net and the nets are hung vertically in the water.
After the scallops grow for some time, they need to be removed from the water for sorting and the nets need to be cleaned of excess marine growth. Biofouling prevents adequate waterflow through the nets and therefore periodically needs to be removed to keep the scallops healthy. There are three common options for removing biofouling. Air drying takes time and smells bad. Power washing requires a pump, power washer, power source, and enough space to wash the nets. And hot water dipping is expensive and can harm gear if not done correctly. Because all these processes take time, growers need to own extra nets in order to keep all their scallops in the water.
Biodegradable Covers
The staff on Hurricane Island operate an experimental scallop farm, and Erin of Ocean Farm Supply makes biodegradable mesh bags for selling oysters and other sea products. Together, they developed the idea of enveloping lantern nets with a sacrificial cover that could collect biofouling, then be composted when it’s clogged with unwanted marine growth. The 100% home-compostable mesh bags sold by Ocean Farm Supply was the perfect option to use as the cover for the lantern nets. The idea is that this will be a less labor intensive and sustainable cleaning option.
At Ocean Supply Farms, Erin sewed together a few of her biodegradable bags into a cylindrical shape that could fit around a lantern net. On the farm at Hurricane Island, they deployed three sets of lantern nets to study how well the idea worked. The first set was just a regular lantern net with scallops inside, the second had a biodegradable cover and scallops, and the third had a cover but no scallops were growing inside. Over the course of a growing season, three separate trials of the experiment can be run. During their month in the water, the covers and nets are periodically removed and weighed to compare the weight of biofouling build-up with and without the covers.
While the experiment is still in its early stages, the results look promising to demonstrate the effectiveness of these covers at reducing the cleaning requirements for biofouled lantern nets. For many growers, purchasing a sleeve of biodegradable mesh might be a much more economical decision than spending hours of time and labor cleaning fouled nets.
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