Research Document - 2005/046

An eel manager’s toolbox for the southern Gulf of St. Lawrence

By Cairns, D.K.

Abstract

Managers who wish to reduce commercial harvests of American eel by a particular amount need to know the relation between rule changes and projected harvest levels. Licence buy-backs could potentially reduce fishing harvest, but a large number of licences would have to be purchased before effort is reduced because of the large number of currently inactive licences. In New Brunswick (Gulf of St. Lawrence sector), shortening the fyke net fishing season would have the greatest effect on harvest if the reduction comes in fall. In Prince Edward Island, effects on harvest would be similar regardless of when during the two month season (mid-August to mid-October) a season reduction was imposed. Effects of increases in minimum legal size on harvest can be estimated from size structure data. For example, the imposition of a 55 cm minimum size is predicted to reduce harvest by 28% in Gulf New Brunswick and by 16% in Prince Edward Island. Increasing minimum distance between fixed gears would likely reduce harvests in areas where gear is currently set in high density, but quantitative predictions are not possible. Reductions of the number of gears per licence could reduce harvest, but effects would depend on rules governing transfer of gear authorizations between fishers. Imposition of a berth system for fixed gear would prevent the artificial increase in effort that comes when fishers place gear for the purpose of thwarting other fishers from taking the site. However, the extent to which such behaviour occurs is unknown. Eels are also subject to recreational spear fisheries in the southern Gulf, whose harvests could be restricted by changes in season, minimum size, or daily bag limits. Reliability of quantitative predictions of harvest reductions are constrained by changes in size structure that arise from fisheries and other causes, from natural population fluctuations, from limitations in the quality of data, and from behaviour of fishers. This paper provides an interim assist to managers who seek short-term predictions of management measures, pending the development of more robust predictive models.

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