Reproduction of the silver John dory Zenopsis conchifer (Actinopterygii: Zeiformes) based on virgin stock condition

Author(s)

Vaz-dos-Santos, Andre Martins ^[1] ; Del Bianco Rossi-Wongtschowski, Carmen Lucia ^[2] ; Honji, Renato Massaaki ^[3] ; Bannwart, Denis ^[2]

Affiliation

^[1] Univ Fed Parana, Dept Biodiversidade, Lab Esclerocronol, BR-85950000 Palotina, PR - Brazil

^[2] Univ Sao Paulo, Inst Oceanog, Sao Paulo, SP - Brazil

^[3] Univ Sao Paulo, Inst Biociencias, Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: Biota Neotropica; v. 14, n. 3 JUL-SEP 2014.
• Web of Science Citations: 0

Abstract

This study describes the reproduction of the silver John dory, Zenopsis conchifer, based on data collected before its fishery exploitation in the southwestern Atlantic, Brazil, in the early 2000s. Biological material was collected through bottom-trawl surveys in 2001 and 2002 from depths of 100 to 600 m. A total of 1,056 individuals ranging from 57 to 504 mm Ls were analyzed. A sex ratio analysis showed that males were predominant among the shorter fishes (< 240 mm Ls) and females among the longer ones (> 320 mm Ls). Between 240 mm and 319 mm Ls sex-ratio was 1:1. The silver John dory is a multiple spawner. Spawning is protracted and more intensive during August and November, when both females and males in spawning capable actively spawning and in regression/regeneration stages were predominant. In this period average values of gonadosomatic index were also higher. For both sexes, the first maturation occurs at 220 mm Ls and at 240 mm Ls all fish can be considered adult. The recruitment apparently takes place from February to May. The length-weight relationships fitted to all specimens and for both sexes yielded b coefficients of similar to 2.7. The virgin stock of Z. conchifer here characterized, may serve a basis for future studies on the effects of fisheries on the reproduction of the species. (AU)