SPSG West of Scotland herring Pelagic Trawl
MSC status
Certified as sustainable in April 2012.
Summary
Species: Atlantic herring (Clupea harengus)
Location: Within EU waters - ICES Areas VIa North, VIb, Vb
Fishing methods: Pelagic trawl
Vessels: 28
Number of fisheries: 1
More about herring
Atlantic herring (Clupea harengus) is a pelagic species, with stocks widely distributed throughout the north-east Atlantic, ranging from the Arctic Ocean in the north to the English Channel in the south. Young herring are typically found close inshore, in estuaries or in sea lochs, whilst adult shoals generally occur further offshore. Herring often travel huge distances between spawning, nursery and feeding grounds – a significant factor when considering the management of the fishery.
Herring are demersal spawners. Shoals of herring gather on the spawning grounds and spawn more or less simultaneously - releasing eggs in a single batch. Eggs are laid on the sea bed, on stones, gravel or sand beds. A female herring may deposit from 20,000 up to 120,000 eggs, depending on age and size. The eggs sink to the bottom, where a mucus coat enables them to form layers or clumps. Incubation time varies between 10 to 40 days depending on temperature.
The larvae are between 5 and 6mm at the time of hatching, and early nutrition is provided by a small yolk sac. Only the eyes are well pigmented and the rest of the body is semi-transparent - virtually invisible underwater. The newly hatched larvae drift with oceanic currents. By the age of one-year, herring have a typical length of 10cm, and first spawning occurs at 3 years old. Adult herring have been reported as old as 20 years, but this is very uncommon.
Clupea harengus play an important role in the food chain, consuming zooplankton (copepods, larval snails, diatoms, mysids, euphausiids etc.) and juvenile sandeels. There are no marked differences between the diets of small and large herring; only the proportions of the different food items change with size. Young herring typically capture prey individually, but where prey concentrations reach very high levels, such as micro-layers that occur at fronts, herring are able to swim forwards with open mouth and expanded opercula.
More about the fishing methods
The vessels are modern and technologically advanced with on-going investment in state of the art technology and modern electronic equipment such as sonar, net and catch monitors, which have greatly improved the precision of this method of fishing. 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. The horizontal opening is maintained by mid-water pelagic trawl doors (or by pair trawling) whilst the vertical opening is maintained by chain on the groundline and floats on the headline – although these are not always required – depending on the way the net is rigged. The midwater trawl used by the Scottish pelagic fleet is designed and rigged to fish in midwater, including in the surface water and is therefore not designed to come in contact with the seabed, and any inadvertent contact is extremely rare – and would risk causing damage to the net. The large net (considerably larger than a demersal trawl net) consists of a cone shaped body, ending in a codend with lateral wings extending forward from the opening. Large mesh in the wings herd the fish before tapering to finer meshes in the square, belly and eventually the cod end. Larger mesh near the start of the net is designed to facilitate the escape of escape of small fish and also pelagic invertebrates such as jellyfish which have the potential to be impacted by pelagic fisheries. Although some Scottish vessels retain the flexibility to use purse seine nets, this gear type has not been considered as part of this assessment and is not therefore included in the unit of certification.
Fishery tonnage
The client group caught 14,582 tonnes in 2008, 11,076 in 2009 and established a TAC of 14,356 tonnes in 2010.
Commercial market
West of Scotland herring is landed to processing factories in Scotland, Norway and Denmark. The final destinations for the herring products are Europe, Russia and Africa.
Actual eligibility date
17 July 2011
