mussel farming-aquaculture

Mussel Farming – Simplifying the Farming Cycle

Aquaculture

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Simplifying the mussel farming process with portable underwater monitoring cameras such as Remotely Operated Vehicle (ROV) or surveillance cameras.


Mussel farming is a mix of traditional shellfish farming and innovative and exciting aquaculture.  As the process from seeding to market can span 18-24 months, it is important that farmers have access to tools which will keep their crop safe, are sustainable, and ultimately ensure a bountiful harvest. Let’s take a look at the steps involved in mussel farming and how the use of a Deep Trekker ROV can be beneficial during each stage.

The Mussel Farming Process

Seeding

In the spring, when the water temperature is just right, mussels spawn, releasing eggs and sperm. This marks the beginning of the farming cycle. This “swimming stage” produces mussel larvae which need to be collected. Techniques for their collection are as delicate today as they were when first utilized off the coast of France in 1235. Farmers place frayed pieces of rope or strips of plastic mesh into the water, attaching these short lines to a long line, which is either anchored to the shore or to the ocean/sea floor. These pieces of rope act as a seed collector, which serves as a settlement surface for billions of swimming mussel larvae.  The immediate and constant care of these juvenile mussels is imperative to optimize their development.  

Remotely Operated Vehicle (ROV) Makes for Simplified Observation

underwater drone mussel farming inspection

The DTG2, one of Deep Trekker’s robust and portable ROV’s is deployable from either shore, raft or boat.  Its easy maneuverability means that it can be deployed to observe this critical stage in the farming cycle with minimal disruption to the delicate spawning environment or interfering with the settling water columns which will nourish the new larvae.

After attaching, these larvae form a hard shell and mature into what is called spat.  Usually, around the first of October, when the spat reaches approximately one inch long, they are hand stripped and taken to shore.  The spat are then de-clumped and sorted into size classes before being placed into mesh sleeves or tubes called “socks”.  These socks are then transported back out to the farm waters and hand tied back onto the longlines.  

Related: American Aquaculture in Review | What Tools Aid in Regulating the Industry

As these young bivalves are returned to the water, it is imperative to carefully monitor current conditions, sediment beds, and search for potentially harmful species or nutrients in the water. This can make the difference between the successful implantation or loss of crop through detachment or damage.  The DTG2 ROV can be dispatched daily to observe the water columns. The HD camera provides data and imagery which can improve the success of the seeding farm cycle.  

deep trekker rov controller

Development & Growth

One of the important ecological designs of mussel aquaculture is that everything a mussel needs to survive can be derived from the nutrients supplied in the natural water environment.  Mussels do not require additional feeding by farmers. These filter feeders eat by pumping and filtering water through gill filaments that filter out small particles.  

Frequent observation of water columns with the use of an ROV like the DTG2 can ensure that there is proper nutrient flow, and regular development is taking place. As the crop grows, longlines get heavy and additional floatation must be added to keep the columns afloat, and away from the bottom of the ocean floor.  The DTG2 ROV can assist in quickly determining how low lines are lying, how much and how often flotation should be strategically applied.   

The Harvest

There is no one month in which mussels are harvested.  As their meat remains flavourful year round; harvesting is generally determined by size. Most mussels are considered mature for harvest around 18-24 months on the longline or until they measure 5.5-6 cms (2 inches) in length.  

At this point, harvest ready longlines can contain upwards of 2 tons of mussels each.  Determining buoyancy, watching for predators (such as seals who would make quick work of a mussel column), and observing overall growth patterns of mussels is constantly necessary.

pei mussel farm aquaculture

Long term and consistent monitoring of a mussel farm can be simplified by the introduction of a DTPod surveillance camera which is designed for long term observation in mind.  With the ability to determine depth, temperature and be used as either a drop camera or permanently mounted, the continuous real time data simplifies this stage of the farming cycle.

Conclusion

The benefits realized with the use of an ROV in finfish aquaculture is also being realized in shellfish farming.  As a mechanism for easy and enhanced investigations, ROV’s function as a key component in every process of the harvest cycle.  As the shellfish aquaculture markets continue to grow, Deep Trekker will work to ensure that farmers have all the necessary tools for success.

 

Acknowledgements

Food & Agriculture Organization of the United Nations
Fisheries and Oceans Canada

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