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

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 ,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. Keywords: spawning period and area, length at first maturation, sex ratio, gonadosomatic index. VAZ-DOS-SANTOS

Range expansion of the Atlantic fish Zenopsis conchifer (Lowe, 1852), family Zeidae, in the western Mediterranean Sea

“…As two out of the Table1 continued three individuals were caught in February, there seems to be no seasonal effect related to temperature, which would push the species into the northern part of the western basin. All individuals were caught between 200 and 500 m of depth, within their native range of depth distribution (Vaz-dos-Santos et al, 2014). Such depths, in the western Mediterranean Sea, maintain temperatures around ~13°C across the whole year, with variations depending on the water mass circulation (Migon et al, 2020).…”

Histopathological Changes in Estuarine Catfish: A Temporal Approach in a Marine Protected Area

“…This study was carried out within the scope of the environmental monitoring and diagnosis research project entitled "Impact of xenobiotics on the estuarine teleost metabolism", which has been carried out since 2004 with bioindicator catfish in the CIELC [4,8,9,11,12,19,20,21,22] 1) and analyzed regarding pathological changes in the hepatic tissue of the fish. The sampling sites were properly georeferenced using a GPS device (vessel).…”