Scallop Fisheries

Current projects

Closed Area Monitoring

The Isle of Man has a series of closed or restricted areas within the 3 mile inshore limit, most of which are in place to provide protection or enhancement for the scallop fishery (e.g. Port Erin Closed Area and Ramsey Bay Fisheries Management Zone), or to act as trial reseeding or ranching areas (e.g. Laxey Bay and Niarbyl Bay Restricted Areas).

Working with DEFA, surveys are carried out onboard either the government enforcement vessel FPV Barrule or using chartered commercial fishing vessels. Recent surveys have primarily focused on assessing king and queen scallop stocks in the Fisheries Management Zone (FMZ) within the Ramsey Bay Marine Nature Reserve (RBMNR). The fishing industry has direct involvement in the management of this site and scientific data helps the fishermen to make decisions about the appropriate levels of fishing or the extension of closures within the FMZ.

The closure of three of these areas (Douglas, Niarbyl & Laxey) was recently extended by DEFA under a temporary order to allow an additional two years of data to be collected. During these two years (2016 – 2017) scientific monitoring of these areas is a high priority and will include assessment of the seabed habitat types, along with scallop density and age and size distributions. The results of this monitoring will give an indication of the areas of suitable scallop habitat that exist within each bay, along with identification of any key conservation features that may be present, together with patterns of scallop growth rates and recruitment. Monitoring these protected areas will also enable comparisons with unprotected areas to be made. The data can also provide general scientific information about how effective the closed areas are and how they respond to the absence or reduction of fishing activity.

Click image to enlarge:

Image: Fisheries closed areas and Marine Nature reserves around the Isle of Man - Isle of Man Government Document


Fisheries for both king (Pecten maximus) and queen scallops (Aequipecten opercularis) operate within the Isle of Man’s territorial waters. These are the two most valuable fisheries to the Isle of Man fleet. The different behaviours of these two species mean that different fishing methods are used with a dredge fishery for king scallops and otter trawl fishery for queen scallops (with a small dredge fishery for queen scallops operating at limited times and within limited fishing areas).

King Scallop, Pecten maximus

In 2015/16 the total number of vessels licenced to fish for king scallops is 157; in 2015 2,345 tonnes worth £4,502,385 (source: DEFA Economic Digest, 2015) were landed from ICES Rectangles 36E5 and 37E5 by Isle of Man vessels and by UK vessels into Isle of Man ports. As king scallops burrow in the sediment they are fished using a Newhaven dredge. This has teeth that rake through the substrate lifting the scallops into a chain mesh bag.

Queen Scallop, Aequipecten opercularis

In 2015/16 following a public consultation and the introduction of a track record period the number of vessels licenced to fish for queen scallops has been reduced to 48. In 2015 3,799 tonnes worth £2,369,023 (source: DEFA Economic Fisheries Digest, 2015) were landed from ICES Rectangles 36E5 and 37E5 by Isle of Man vessels and by UK vessels into Isle of Man ports. Queen scallops are active swimmers when disturbed so are fished using an otter trawl. A tickler chain disturbs the sea floor causing the scallops to swim up into the water column, where they are captured in the fishing net. This method is preferred mid-June to October with skid dredges being used in the winter months.

In 2011 the Queen scallop trawl fishery was awarded Marine Stewardship Council (MSC) accreditation as a result of being a well-managed and sustainable fishery. It is one of the largest and most valuable queen scallop fisheries in the world. There has been an increase in demand over the past few years highlighting the importance of continued management of this fishery to ensure its future sustainability. In May 2014 the MSC certification for the fishery was suspended following a decline in queen scallop stocks and a corrective action plan has been enacted to rebuild the stock. As part of the corrective action plan the Isle of Man Government have been participating in a Pan-Irish Sea queen scallop management project, in collaboration with the fisheries administrations of the UK. It is recognised by industry, fisheries scientists and the fisheries administrations that the wider queen scallop fishery is under significant pressure and is showing signs of decline, whilst at the same time lacking any significant control measures. It is the objective of the project to develop and implement suitable management for this fishery in areas VIa and VIIa, which contribute the majority of landings.

Species Ecology

The King Scallop (Pecten maximus)

Description: U:\College of Natural Sciences\Research Data\OCEAN-PROJECT-EFF\Surveys\Survey October 2012\Selection of pictures\IMG_0440 - Pecten maximus.JPG

The king scallop is a large bivalve that can grow up to 15 cm long. The right valve is highly convex and off-white, yellowish, or light brown in colour. The left valve is flat and light pink to reddish brown in colour. Both valves have 15-17 radiating ribs.

Habitat & Distribution

King scallops are usually found in shallow depressions in the seabed. They prefer clean, firm sand, fine or sandy gravel, but are occasionally found in areas of muddy sand. It is found along the European Atlantic coast from northern Norway and south to the Iberian Peninsula. It has also been reported off West Africa, the Azores, Canary Islands and Madeira. King scallops are filter feeders and eat micro-organisms in the water column.

Life Cycle

Their lifespan can be up to 20 years and they reach sexual maturity between 3 and 5 years. King scallops have both male and female reproductive organs (hermaphrodites) and fertilization takes place externally. Their larvae develop in the water column and are dispersed in the currents. After 30 days they settle to the sea floor and attach to a suitable surface using their byssal threads (strong, silky fibres). Young scallops usually remain attached by byssal threads until they are between 4 and 13 mm in length and then settle on the seabed.

It is believed that adult king scallop do not migrate and only move when disturbed. Therefore, their distribution relies heavily on larval dispersion and consequently the local environmental conditions, such as currents and temperature.

The Queen Scallop (Aequipecten opercularis)

The queen scallop is a medium-sized scallop with two convex shells of variable colour. It is often light-pink to brown, orange or yellow, and may be overgrown with encrusting sponge. This species can grow to 9 cm in diameter.

Habitat & Distribution

Queen scallops are usually found between tidemarks up to depths of 100 m. They are often found in high densities on sand and gravel substrates and lie on top of the seabed instead of becoming settled in the sediment like the king scallop. They have also been found amongst horse mussel beds. This species is found from South of Norway to the Mediterranean and the Canary Isles. Queen scallops are filter feeders and eat micro-organisms in the water column.

Life Cycle

The lifespan of the queen scallop can be from 6-10 years and they reach sexual maturity at 1 year. Queen scallops have both male and female reproductive organs (hermaphrodites) and fertilization takes place externally. Their larvae develop in the water column and are dispersed in the currents. After 11-30 days the larvae settle from the water column and attach to suitable substrates by their byssal threads (strong, silky fibers). Young scallops remain attached by byssal threads for a period of time and then settle on the seabed.

Queen scallops are known to be quite mobile and swim readily in response to disturbances such as predators, divers, and fishing gear. They swim by rapidly opening and closing their shells which allows the scallop to rise off the seabed at a steep angle before swimming horizontally for a short distance and sinking back to the seabed.





MSc & PhDThesis

Additional documents