Publication Abstract

Estimating and forecasting pre-fishery abundance of Atlantic salmon for the management of mixed stock fisheries

E.C.E. Potter, W.W. Crozier, M.C. Nicholson, P-J. Schon

The majority of the exploitation of Atlantic salmon takes place close to or within the rivers of origin of the stocks. However, salmon from rivers in both North America and Europe, principally the southern countries, are caught in the mixed stock fishery operating off the west coast of Greenland, and the Faroese fishery, although not currently operating, has taken salmon from all European salmon producing countries. Provision of robust quantitative catch advice for these fisheries therefore depends upon being able to forecast the stock abundance for about 2000 salmon river stocks around the North Atlantic, over 1500 of which are in Europe. A ‘NEAC-PFA’ model has been developed and refined for estimating the pre-fishery abundance (PFA) of salmon in the NASCO- NEAC area based upon catch data and estimates of non-reporting rates and exploitation rates. Use of alternative approaches, based upon estimation of juvenile production, have so far proved unsuccessful because of lack of data. Alternative methods for estimating the numbers of returns which incorporate both counter and catch data are also being considered. Estimates of PFA and spawner numbers derived from the NEAC-PFA model and environmental data have been used to try to develop models to forecast stock abundance, but forecasts have been strongly influenced by the strong temporal trends, declining, in stock abundance. Consideration is being given to alternative modelling approaches, including the use of Bayseian techniques.

Reference:

E.C.E. Potter, W.W. Crozier, M.C. Nicholson, P-J. Schon, 2003. Estimating and forecasting pre-fishery abundance of Atlantic salmon for the management of mixed stock fisheries. ICES CM 2003/V: 21. 18pp. ICES Copenhagen.