Fishing Methods

Pelagic vessels are specifically designed to hold only pelagic species in chilled seawater tanks.

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In Ireland, there are 22 vessels which target only pelagic fish, with a further dozen or so vessels that target pelagic fish at certain times of the year. The dedicated pelagic vessels are called Refrigerated Sea Water vessels or RSW vessels for short and are only active for about 5 months of the year targeting a single species at a time. 

RSW Vessels

The RSW vessels have tanks onboard which are filled with sea water. The water is cooled by a refrigeration plant to bring the temperature down to 0°C before the first fish are pumped into the tanks.

The water in each tank of fish is circulated by drawing it from the top of the tank, passing it through a shell and tube heat exchanger, and returning it to the bottom of the tank, thus forcing it up through the mass of fish to promote rapid and uniform cooling.

Pelagic Nets

A typical Irish RSW vessel uses pair pelagic trawls for targeting pelagic species. Pelagic trawls are much larger than trawls which catch whitefish. The trawls are normally towed between two vessels, at around 4.5 knots.

Pelagic trawls are towed at the appropriate level in the water column to intercept target shoals, with gear depth being controlled by altering towing speed and/or warp length. As a result, there is no impact on bottom habitats and bottom structures.

Sophisticated sensors on the net can tell the skipper how much fish is in the net, allowing the skipper to have control over how much fish can be caught at a time. This is important as each vessel has its own quota for each species and if they are coming close to the amount they can take, they can set the sensors to only catch the remaining amount they are allowed.

Onboard the Vessels

The RSW vessels are modern and technologically advanced with on-going investment in state of the art technology. Modern electronic equipment such as sonar, net and catch monitors has greatly improved the precision of this method of fishing. The majority of crew onboard the pelagic RSW vessels have been working on the same vessel for years, and with many of the vessels being family businesses, it's not uncommon to find family members working together. There are normally between 9 and 10 crew onboard, including deck hands, engineers and skipper. The Marine Survey Office (MSO) checks that all the crew certificates are to the necessary standard when issuing a Certificate of Compliance for the vessel.

The Irish RSW fleet

The first purpose built Irish pelagic RSW boat was built in 1979. Ireland now has 22 ultra-modern pelagic vessels ranging between 27 and 71m in overall length and with an average age of 12 years. These vessels largely fish out of Killybegs, located in the northwest of Ireland and target large pelagic shoals of mackerel, herring, horse mackerel and blue whiting during the spring, autumn and winter.

Although most of the fishing effort is focussed off the west coast of Ireland, the mobile nature of these species, particularly mackerel, requires that these vessels fish off Scottish and Norwegian coasts.