An industry group has proposed a novel system for managing the Northeast Multispecies Fishery. Each harvester would be endowed with a budget of points, and each species would have a “point price,” or number of points that must be paid out of his budget when landing that species. By varying the point prices throughout the season, management could redirect effort across species. This paper presents a benchmarked experimental testbed of this management system, and shows that harvesters do respond to point prices, which can be chosen to support harvest of most of the allowable catch of each species without severely over-harvesting any of them.

Many factors influence the dynamics of fisheries and feedback mechanisms amongst these factors are poorly understood. The ecological systems are too large and complex to conduct controlled experiments and economic adjustments to changes in fish populations defy traditional equilibrium analysis. New modelling approaches are required to identify the driving forces behind the dynamics of exploited fish populations, assess likely consequences of alternative management measures, and achieve consensus among stakeholders.

We present an interdisciplinary modelling approach that can be used easily to assess dynamic consequences of alternative assumptions for certain key biological and economic parameters, and incorporates the input of various stakeholder groups in the fishery. Contributions of scientists, economists and managers to the model can be augmented with contributions from the fisherfolk.

Our approach is illustrated by a dynamic computer model capturing the interactions of three demersal fish species on Georges Bank, namely Atlantic Cod (Gadus morhua), Haddock (Melanogramus aeglefimts) and Pollack (Pollachius virens), population sizes of which are assumed to be density-dependent for the purposes of the model and are significantly affected by management decisions. The model addresses how management measures for one species influence the population dynamics of other commercially exploited species. Various scenarios are run to explore the implications of viable management strategies under alternative assumptions on the driving forces behind complex ecological-economic processes. The analyses indicate that neither small reductions in effort nor mesh size increases are likely to prevent the further demise of the Georges Bank ground fisheries, and, in fact, stocks of the three targeted species may decline. Alternative management measures seem to be necessary to prevent collapse, and might include various strategies, such as effort controls and mesh size reductions, in conjunction with a dramatic change in fishing technology. The assessment and viability of alternative management measures in turn require that consensus is generated among stakeholders about data and models.

Une analyse des correspondances multiples et une classification ascendante hiérarchique ont été utilisées pour étudier les variations de rendements par espèce entre 1972 et 1989 de navires de la pêche chalutière hauturière française. L'application de ces méthodes permet de mettre en évidence les relations parfois complexes qui lient les rendements des principales espèces débarquées au sein des rendements totaux et de dégager une partition des profils de rendements caractéristique de cette période. Les facteurs comme l'année et les secteurs de pêche sont ceux qui expliquent le mieux les variations observées; les variations saisonnières jouent un rôle secondaire. Les rendements augmentent et se diversifient entre 1972 et 1989. L'étude montre que ces évolutions peuvent être reliées pour une part à des changements dans les stratégies d'allocation d'effort de pêche et dans la composition des flottilles. Les chalutiers qui exploitaient traditionnellement le golfe de Gascogne au début des annéessoixante-dix ont reporté leur effort sur des secteurs situés plus au nord (nord de l'Irlande et ouest de l'Ecosse) et ont été remplacés par des chalutiers de taille et de puissance plus importantes. Dans les années quatre-vingt, une autre composante fait son apparition. Elle est constituée par des chalutiers de taille plus réduite qui exploitent des secteurs plus côtiers que les précédents.