Effects of Measurement Errors on the Assessment of Stock–Recruitment Relationships

Abstract

Errors in measuring spawning stocks can have a profound effect on the appearance of stock–recruitment relationships. Large errors make recruitments appear to be independent of spawning stocks. This effect promotes overexploitation rather than simply making the relationship noisier and harder to measure. Efforts to explain variation in recruitment through factors other than spawning stock may be deceptive as well. Much fisheries theory and practice are based on the assumption that recruitment is largely independent of spawning stock; that assumption is not credible except in cases where spawning stocks are known to have been measured accurately.Key words: stock, recruitment, statistics, overexploitation