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Abstract
Annual recruitment of the NewZealand longfin eel (Anguilla dieffenbachii) hasdecreased
by 75 per cent since significant levels of commercial fishing began in the early 1970s.
This motivates application of a multiple-cohort bioeconomic model to a New Zealand
longfin eel fishery to investigate its optimal management and ascertain the suitability
of existing regulatory policy. The use of historical harvest to calculate total allowable
catch is asserted to be unsustainable based on recovery dynamics. In addition, individual
transferable quota systems are argued to be fundamentally flawed for the protection of
longfin fisheries because of high-grading, low-surplus production and a current lack
of effective stock-assessment procedures. Area closure and the spatial definition of
harvest rights are attractive alternatives given the territoriality of longfins and high larval
spillover. The importance of unfished reserves is reinforcedwhen significant uncertainties
regarding population strength, harvest intensity and growth dynamics are considered.
Restriction of exploitation to older cohorts in fished areas is demonstrated to maximise
economic yield.