Abstract
The efficiency of a Renfro beam trawl net was tested in vegetated and nonvegetated habitats of Términos Lagoon, Mexico. The white shrimp, Penaeus setiferus (87%), predominated over the brown shrimp. Penaeus uztecus (13%), in the naked substrate (Palizada Vieja), whereas the pink shrimp, Penaeus duorarum (98%), was the most abundant penaeid shrimp in the habitat with vegetation (Pájaros Island). In the substrate covered by vegetation, only the brown shrimp (2%) was present in addition to pink shrimp. Estimated penaeid shrimp density through the first sample ranged from 1.2 and 1.3 org. rn–2 in Palizada Vieja to 1.8 org. rn–2 at Pájaros Island. The efficiency of the beam trawl net was estimated at 28% in naked substrate when trawlings were done countercurrent. Net efficiency decreased to 17% when trawlings were done along the water flow. Net efficiency on vegetated substrates was estimated at 15%. Size composition of the first tow was significantly different (Χ2, P = 0.05) from the total size distribution of penaeids present in the area enclosed in both substrates, although mean sizes were similar. However, the size distribution obtained with two replicates did not show significant differences in both substrates at the same probability level.
Highlights
El ciclo de vida de los camarones peneidos consta de diferentes estadios que se desarrollan tanto en el medio ambiente marino como en el estuarino
An experiment was carried out to evaluate the sampling efficiency of the Renfro beam trawl net in naked substrates as well as in substrates covered by vegetation, which can serve as a comparison for previous studies and as referente for future works that use this sampler
The study was carried out at both sites from 7 to 10 December 1987, in order to consider the operation of the net in naked substrates and in substrates covered by vegetation
Summary
El ciclo de vida de los camarones peneidos consta de diferentes estadios que se desarrollan tanto en el medio ambiente marino como en el estuarino. Estas zonas costeras son utilizadas por el camarón como áreas de crianza, por periodos variables de dos a cuatro meses según la especie, ya que les proporcionan alimento y refugio de los depredadores. El establecimiento de postlarvas planctónicas en las áreas costeras y su desarrollo hasta ser juveniles constituye una de las etapas mas importantes en la regulación del tamaño de la población del camarón (Gracia, 1989). Las condiciones ambientales del hábitat estuarino que determinan el espacio y alimento disponibles para esta etapa son críticas para la determinación del nivel de reclutamiento de la población adulta (Gracia, 1989, 1991, 1992)
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