Marine Harvest – the Colonsay Fish Farm

A few notes by Kevin Byrne who was lucky enough to get a good look on Day 1; all figures and dimensions are mere guesswork, hopefully can be corrected.


The barge with Emma C alongside

The barge to service the new Colonsay Fish farm was brought into position on Friday 5th June 2015, following a rather lengthy tow at a maximum speed of 4 knots. The investment in the new farm approaches £5.5m and the magnificent barge unit alone cost ca. £1.25m, having been built at Inverness by GaelForce. It is a most impressive piece of engineering and Marine Harvest staff quite rightly remarked that they were proud to know that it was built here in Scotland. Having just arrived, it was still being positioned by an anchor-laying vessel, secured by 8 large danforth-style anchors each weighing 3 tonnes and fitted with very heavy chain.


After deck, and upper deck with hopper hatches and undeployed fendering

The barge rises about 35ft out of the water, and is almost square, maybe 70 ft x 70ft – there are access ladders on both sides, leading to small side decks. The after deck is open, almost the full width of the vessel and giving perhaps 15ft x 60ft of workspace. The forward deck houses feed delivery equipment, leading to 6 substantial delivery pipes, one for each fish cage and sufficiently powerful to be all operational together if required. An upper deck to the central portion houses four hatches, covering four feed hoppers which run the full height of the vessel, much of which seems to be under the waterline ... these hoppers seem to be about 50ft deep and about 20ft square. Entry to the central accommodation area is from a side deck and leads into a large vestibule designed for donning, doffing and storage of foul-weather gear. To one side is a smart, easily maintained laboratory for the handling and examination of samples of product, feed etc. To the other side of the vestibule there is a generously proportioned shower-room.


Galley, Mess table and Bridge (awaiting monitors etc.)

Leaving one's outdoor boots or shoes, one passes from the vestibule into a large bright and very well-equipped cabin with mess dining facility and comfortable seating area, with an enviable fully equipped galley to one side (including a dishwasher). The cabin includes facilities for pc connections, and has video screen installed, being fully equipped for training presentations. From the cabin, a short flight of stairs leads to the bridge, which includes a monitoring position for observation of the fish cages, together with over and under water cameras and much technical equipment. Apparently the efficient supply of feed (at £1k per tonne) is critical to the success of the venture - the target to beat is currently 100:104 meaning that no more than 0.4% of supplied food should go astray due to effects of current or other factors; foolishly one forgot to ask how much food is used per annum, but if it was 1000 tonnes the potential wastage would be about 1 kg per day. The bridge also houses a neat and well-finished office for the site manager.

The after deck houses an access hatch to a facility for “mortalities” – any fish casualties are recovered from the sea and processed in such a way as to render them safe for storage; there is thereby no danger of cross-contamination of the fish stocks and no pollution of the sea – the storage tank is emptied as and when required via a discharge pipe into a supply vessel and the material is taken to the mainland for final disposal.


Mortalities mascerator; Carpenter's shop; Dell with Mortalities tank in distance

An access door from the after end leads to a companion way and there is a small mezzanine deck which houses the carpenter's workshop. At a lower deck the generators are housed, main and reserve and both independently capable of powering the entire operation; supply seems to be 3 phase 400 volt, but reduced to 240 volt for the domestic purposes. On another deck below the after deck there are two very substantial diesel tanks, and from the lowest deck there is access to the base of the four feed hoppers. These can be operated singly or as required, and each is provided with the sort of sliding mechanical closure that one associates with any hopper; when in use the feed is fed by gravity to an Archimedes-screw which leads it into an inspection box and onwards to the pipes along which it is to be blown to the fish cages. It is worth noting that every such work station is equipped with emergency cut-off buttons, and all areas of the vessel and the farm itself are monitored by CCTV.


Under the feed hoppers; Spanish arch; Two of six airpumps, air vents on deck behind

The bulkheads between each section of the lower deck are pierced by “Spanish” arches, a practical arrangement which also adds a pleasing touch. Moving forward through the feed-hopper zone, one enters the forward section, below the bridge. Again there are three decks, housing the freshwater supply, the holding tank for “mortalities” and six extremely powerful pumps which use air both to deliver feed directly to the fish tanks and also to aerate the water as required, for example in the case of possible algal bloom, jellyfish incursion etc.

In addition to the permanently-sited barge there will be six cages, and two 6m RIBs for servicing them. Access to and from the site is by 10m RIB based at Scalasaig, and there is also a purpose-built landing-craft style vessel which was constructed in Holland and to be named Beinn Eibhin.


All in all, this enterprise seems to be designed and implemented to extraordinarily high standards - the working environment is stable, ergonomically designed and appears to outrun all obvious H&S standards. The working pattern seems to involve two teams of five people, who will normally work 12 hr shifts 24/7 on a fortnight on/off basis. It is clear that the company and the staff are committed to the very highest environmental standards and that this project offers a great future for all concerned, including everyone in Colonsay. The project was first mooted a few years ago and was the subject of numerous meetings and informative sessions, culminating in a democratic vote at which it received overwhelming support.