Where is Fisheries Science Heading – How Can Fish Stock Assessments be Improved

Abstract

Much of the relevant knowledge gained from the enormous amount of research carried out in fish population dynamics remains unused in stock assessments and predictions. A main challenge is to utilize more effectively the increasing scientific knowledge of factors and relations influencing fish stock development, including effects of a varying physical environment and multispecies interactions. Present stock assessments are often characterized by a lack of search for causal relations and explanations, concentrating the effort on the technical/mathematical aspects of the predictions. Recent stock assessment reports are certainly more advanced from a statistical and analytical/mathematical point of view than older reports, but they often contain less natural science. In particular, VPAtuning procedures underestimate the value of critical discussion of basic biological assumptions and use of independent knowledge of fishing fleets and surveys. Predictions should not be limited to the usual option tables, giving catches next year and stock size for the following year for a range of fishing mortalities. More research effort should be directed towards the problem of predicting long-term effects of various exploitation strategies and study effects of exploitation on not only stock size, but also on stock structure and resulting effects on stock dynamics and the stock’s adaptation to a fluctuating environment.