A comparison of no-take zones and traditional fishery management tools for managing site-attached species with a mixed larval pool

Abstract

No-take zones (NTZs) can generate higher larval production by sessile, sedentary and site-attached species per unit area than in exploited areas, and may increase recruitment and yield compared to status quo management. Whilst NTZs may be considered an essential part of optimal management, few studies have specifically compared the effects of NTZs with those of correctly applied gear and effort controls.

A yield-per-recruit (YPR) population model, based on the sedentary abalone Haliotis laevigata, was used to compare the effects of management by minimum landing size (MLS), effort limitation and NTZs, either singularly or in combination. Initially, a minimum basic YPR model was used. Three additional assumptions were sequentially added to the model to see if they affected conclusions drawn from the model. The additional assumptions were the inclusion of: (i) a length–fecundity relationship; (ii) an age-dependent natural mortality function; and (iii) mortality of undersized individuals due to fishery operations. In the absence of undersized mortality caused by fishing, under virtually all conditions the population is best managed with a combination of MLS and effort control, without any NTZs. For simulations that included mortality of undersized individuals in the fished area, under nearly all circumstances NTZs were considered an essential part of optimal fishery management, and management incorporating NTZs greatly increased the sustainable yield that could be taken.

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ORCID for J.G. Shepherd: orcid.org/0000-0002-5230-4781

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