Unmanned Equipment in Aquaculture

Work that used to need a diver increasingly does not. The reason has less to do with labour cost than with how often the job needs doing, and a diver you have to call out is a job you quietly postpone.

Resident robots changed the model

Nets need cleaning constantly. Fouling starts the day the pen goes in, and the traditional answer was periodic high-pressure washing, which strips the antifouling coating off the net and blasts the accumulated growth into the water column as a plume that settles straight onto the fish below.

Remora Robotics built a robot that lives in the pen, cleaning lightly and inspecting as it goes. Nothing gets deployed. Nothing gets recovered, and the net never reaches the state where aggressive cleaning becomes necessary in the first place.

The pattern generalises. Resident systems beat visiting ones whenever the task is continuous, and they win by changing the maintenance regime rather than by doing the same job faster.

Navigating a net is its own problem

A seabed holds still. A net moves with the current, flexes under load, and offers nothing stable to navigate against.

Work on hydroacoustic navigation for net pen inspection has paired Doppler velocity logs with USBL positioning, using the DVL to track against the net surface rather than a seabed that may be far below. Both together give reliable autonomous coverage. Either alone does not.

Vision-based approaches run alongside, with active vision systems doing real-time net inspection from an ROV. Water clarity is the failure mode, and a vehicle leaning on cameras goes blind exactly when the site is most turbid and you most want to see the net.

Feeding is where automation started

Automated feed systems predate the robotics by decades. They remain the largest single lever on farm economics, because feed is the dominant operating cost and overfeeding both wastes money and drops uneaten pellets onto the seabed under the pen.

Camera-driven feeding closes the loop. Watch the fish. Detect when the feeding response drops off, and stop, which is a decision worth making several times a day rather than once. Stingray's Orbit One folds feeding support in beside lice detection, biomass estimation and environmental monitoring on one winch.

Surface vessels and the move offshore

Uncrewed surface vessels handle site survey, mooring inspection and environmental monitoring. Their value grows as farms move into deeper, more exposed water, where sending a small boat out depends on the forecast and occasionally puts a crew at real risk.

Offshore expansion drives most of this. Exposed sites flush better, cut disease pressure, and avoid fighting other coastal users for space. They also mean equipment has to survive real sea states and keep working with no technician available at short notice.

Autonomy stops being a cost saving at that point and becomes the only way the site operates at all.

What still needs a person

Mortality removal, treatment operations, harvest, welfare calls. Handling live animals is a dexterity problem wrapped around a judgement problem, and subsea manipulation is nowhere near either of them.

Divers still go in. Less often, for shorter periods, and usually to deal with something a robot spotted first.