Clupea harengus is a schooling species that inhabits the Atlantic ocean and the Baltic Sea. It forms big schools of similar sized IND, although sometimes ADULTS and JUVENILES get mixed in the same school. The schools are especially large during migrations to spawning grounds. Due to its small size and its schooling behaviour, C. harengus is one of the most frequently fished species in the world in terms of number of IND. Many countries have regulated the landings and some have closed the spawning grounds to ensure a restoration of the decimated populations that were suffering from overexploitation. Fisheries target ADULTS, SPAWNERS, and JUVENILES. The most common fishing method nowadays is purse seine. JUVENILES are also traditionally caught by different types of methods. C. harengus has an important role in the ecosystem, since it incorporates zooplankton into the trophic chain and is then predated by a vast number of larger species. Decreasing distance to neighbours – especially during crowding – and contact with the gear are the most frequent welfare hazards during catching with purse seine. Avoiding crowding or keeping it short – particularly at the peak density – may avoid a steep decrease in welfare. Usually, IND are pumped out of the net onto the vessel which allows them to stay in water, but the arrival on deck may be accompanied by injuries and stress. If not already crushed, the most common ways to die are by asphyxia or hypothermia. A protocol for stunning and slaughter is urgently needed.
