Chair of the Advice Drafting Group on Southern horse mackerel, anchovy, sardine (ADGHANSA, see the corresponding expert group page) Harald Gjøsæter.
'Some of the fish species ICES gives management advice for are called short-lived, as opposed to long-lived. There is no clear definition of this term, but normally we call those species that live to 4-5 years or less short-lived. Examples are the anchovy around the Iberian Peninsula and the capelin in the Barents Sea. These species represent a challenge to stock assessment and management, mainly because they may recruit (survive to join the fishery population) during their first or second year of life, which means that the fishing opportunities are very dependent on the incoming year class (fish born in same year) every year.
Often, a so-called spawning escapement strategy is applied when managing such fisheries. This simply means that one should let a certain amount of spawners survive the fishery to enable good recruitment each and every year. To get a reliable estimate of the incoming year class at an early stage is a major challenge with such species, but a prerequisite when it comes to giving advice to managers about fishing opportunities.
Short-lived fish species are normally placed rather low in sea foodwebs, and some of them are called forage fish because so many predators in the ecosystem depend on them as food. Their function in the ecosystem is to channel energy from zooplankton and upwards through the trophic pyramid. This also makes advising on a fishery difficult, since in many cases one has to take into account the crucial role of the short-lived species for the rest of the ecosystem when giving advice.'