Spatial and temporal aspects of the decline in cod (Gadus morhua L.) abundance in the Kattegat and eastern Skagerrak

We explored the temporal and spatial evolution of cod abundance along the Swedish west coast during the past 20–40 years. Analyses of cpue data from the Swedish Nephrops fishery revealed a persistent decline in offshore abundance since the beginning of the 1980s in both the Skagerrak and Kattegat, culminating in extremely low densities in the late 1990s. Owing to a lack of reliable logbook and survey data for the area inside the trawling limit, informal statistics such as records of sport fishing clubs and notes on catches made by a coastal fishermen were used to sketch the development of cod abundance in the coastal zone. These data indicate that the decline in catches of inshore cod preceded the one in offshore areas at the end of the 1970s. The information presented indicates that the depletion of the cod stock in these areas is much worse than suggested by routine annual assessments.