Predicting total allowable catches for Icelandic capelin, 1978-2001

A winter fishery for capelin, Mallotus villosus (Muller), began in coastal waters off south and southwest Iceland in the mid-1960s. After successfully expanding to the shelf area east of Iceland in 1973, the winter capelin catch increased to >400 000 t. A summer fishery was started in 1976 in deep water north of Iceland, and annual landings rose to >1 million tonnes by 1978. The first regulatory measures for the fishery were set early in the 1970s, aimed at protecting the juvenile part of the stock. In 1979, a target of 400 000 t of remaining spawning stock was adopted. Predictions of fishable stock size were erratic in the 1970s. While summer and autumn catches remained high, stock abundance declined, and the target for remaining spawning stock was not met in the early 1980s. Since 1978 the adult fishable stock has been assessed annually by acoustics. A model for predicting fishable stock abundance from summer assessments of juvenile capelin (ages 1 and 2) was established, and it worked well until 1989. The current model for predicting fishable stock biomass was then developed, based on autumn data on juvenile capelin. Using the available data sets somewhat differently from before, we have developed a third model for predicting fishable stock biomass. The construction of the three predictive models is explained and evaluated. It is concluded that both the current and the new models can be used to set preliminary catch quotas for the next fishing season.