Steven Mackinson

Integrating local and scientific knowledge: an example in fisheries science.

Attempting to predict the spatial dynamics fish stocks, as required for management, is an ominous task given our incomplete understanding of biological and ecological mechanisms underpinning behavioral responses of fish. Large gaps still exist in our basic scientific knowledge. Nonetheless, the knowledge of fishers and fishery managers is not incorporated into our scientific analyses, even though such information is rich in observation since knowledge of fish behavior and distribution is a prerequisite for their profession. Combining such observations with more conventional scientific studies and theoretical interpretations provides a means by which we may bridge some gaps in our knowledge. Presented here is an example of how both local and scientific knowledge can be integrated in a heuristic model. The model, CLUPEX, is developed in the framework of a fuzzy logic expert system and uses linguistic statements written in natural language to capture and combine knowledge sources in the form of IF … THEN rules. The rules are inferred from interviews with experts and fishery professionals including fishers, fishery managers, scientists, and First Nations people. The knowledge base, comprised of the set of rules, is flexible in the sense that it can easily be modified to add additional information or change current information. Using input pertaining to biotic and abiotic environmental conditions, CLUPEX uses the rules to provide quantitative and qualitative predictions on the structure, dynamics and mesoscale distribution of shoals of migratory adult herring during different life stages of their annual life cycle.

The challenge of the herring in the Norwegian sea: Making optimal collective spatial decisions

Norwegian spring-spawning herring, Clupea harengus harengus L., are long-lived multiple spawners subject to strong variation in recruitment success. They tend to adopt low-risk, preferred-conservat...

Bioeconomics and catchability: fish and fishers behaviour during stock collapse

Abstract During periods of stock collapse, an increase in the catchability exhibited by many small pelagic fish is a consequence of two factors: their schooling habit and the remarkable efficiency of todays technology intensive fishing fleets. The net result is that a virtually constant catch per unit effort may be achieved regardless of stock size. Three models of catchability used to highlight the consequences of fish behaviour and fishing technology during stock collapse (Pitcher, 1995) are extended to examine the effects of incorporating profit motivated economic behaviour of fishers. Three scenarios are examined: (1) cooperation by fishers to achieve maximum economic yield (MEY); (2) non-cooperation resulting in open access equilibrium; (3) non-cooperation with allocation of subsidies allowing fishers to increase effort beyond the open access equilibrium. Incorporating economic behaviour in the density-dependent catchability models may result in an alarming increase in the rate of stock depletion, since fishers maintain high profits even during low stock abundance. We discuss the consequences of using a model where catchability is assumed constant for the management of fisheries on small schooling pelagic fish.

Mixed-fishery or ecosystem conundrum? Multispecies considerations inform thinking on long-term management of North Sea demersal stocks

Signatories of the 2002 World Summit on Sustainable Development declaration committed to maintain or restore fish stocks to levels that can produce the maximum sustainable yield (MSY), a goal that has been challenged on a number of grounds. The European Commission has stated an objective to manage fisheries (independently) to achieve MSY by 2015, which has catalysed the Regional Advisory Councils’ (RACs) thinking on MSY and how it relates to their goal of developing long-term management plans. This study uses an ecosystem model of the North Sea to investigate questions relating to MSY in the context of mixed demersal fisheries for cod, haddock, and whiting. Results suggest that it is not possible to simultaneously achieve yields corresponding to MSYs predicted from single-species assessments and that the contradictory response of whiting is central to the trade-offs in yield and value for mixed demersal fisheries. Incompatibility between mixed-fishery and ecosystem-scale considerations exemplifies the dif...

An adaptive fuzzy expert system for predicting structure, dynamics and distribution of herring shoals

For many of the worlds pelagic stocks, structure, dynamics and mesoscale distribution of fish shoals has considerable importance to central issues in fisheries management; stock structure, stock assessment, resilience and harvest control. A model is presented here, that attempts to bridge existing gaps in our basic understanding of the biological and ecological mechanisms underpinning the behavioural responses of herring, and how these govern spatial dynamics of shoals. The model, CLUPEX, is developed in the framework of an expert system and utilises fuzzy logic to capture and integrate scientific and local knowledge in the form of heuristic rules. Using input on biotic and abiotic environmental conditions, CLUPEX uses the rules to provide quantitative and qualitative predictions on the structure, dynamics and mesoscale distribution of shoals of migratory adult herring during different stages of their annual life cycle. Test predictions corresponded well with observed patterns, although accuracy for specific circumstances may be limited by the resolution of the knowledge. However, by adding specific local knowledge and adjusting weighting parameters, CLUPEX can be adapted to provide more accurate and precise predictions. The user interface combines hypertext and an explanation facility that is fully cross-referenced to a database, to provide an intuitive and transparent feel rarely found in more traditional analytical models.