Relative yield-per-recruit and management strategies for &lt;i&gt;Cynoscion acoupa&lt;/i&gt; (Perciformes: Sciaenidae) in Lake Maracaibo, Venezuela

Orlando José Ferrer Montaño,Isabel Cristina Morales

doi:10.15517/rbt.v61i1.10943

Abstract

Acoupa weakfish, Cynoscion acoupa, in Lake Maracaibo is subject to intense commercial fishing by an artisanal fleet, and a recent decrease in fish size observed from landings is of concern. This fishery has not yet been modeled, and its assessment and the establishment of management practices to overcome the current overfished condition are urgently needed. To address this, we used recent and past empirical growth estimates to model relative yield-per-recruit under different lengths at first capture. Our results from relative yield-per-recruit analysis showed evidence that growth and recruitment overfishing occur under current fishing practices in Lake Maracaibo. Particular attention was given to fishing practices in El Tablazo Bay where young, small fish predominate in the commercial catches (mean total length=33.7cm), well below the length at first sexual maturity (-40cm TL) for both sexes. As management strategies, we propose to set a mesh size limit at or above 8.89cm (3.5in), which will reduce fishing mortality of immature fish, increase yield-per-recruit, and will result in an increase of Acoupa weakfish recruitment for the long term in Lake Maracaibo.

Highlights

All Lake Maracaibo fishing is carried out on a small scale, scattered, and without defined landing points (de Espinosa 1972), making it difficult to manage, given the difficulties to obtain reliable catch statistics
The von Bertalanffy growth function obtained by Morales (2009) was Lt=80(1-e-0.26t), whereas the obtained by OJFM was Lt=98.1(1-e-0.26t) and the reported by de Espinosa (1972) was Lt=105.5(1-e-0.27(t-0.21))
Relative yield-per-recruit for de Espinosa (1972) and OJFM indicated that levels of F were slightly below that for the maximum potential yield-per-recruit (Fig. 1A, TABLE 1 Parameter values used in relative yield-per-recruit simulations for Acoupa weakfish Cynoscion acoupa de Espinosa (1972) Ferrer Montaño Morales (2009)

Summary

Introduction

All Lake Maracaibo fishing is carried out on a small scale, scattered, and without defined landing points (de Espinosa 1972), making it difficult to manage, given the difficulties to obtain reliable catch statistics. Fishers in Lake Maracaibo take advantage of this noise to set their gillnets targeting both mature males and females Acoupa weakfish specimens Local fishers call this fishing method pesca de tronío (de Espinosa 1972). Pertinent data gathered from papers by de Espinosa (1972), Ferrer Montaño (unpublished data), and Morales (2009) were compiled and analyzed to generate models predicting Y’/R under diverse management scenarios. These models were used to determine whether regulations such as size limits and effort regulations are necessary to manage the Lake Maracaibo Acoupa weakfish fishery

Methods

Results

Conclusion