The aim of this investigation was to study macroscopic and microscopic structures of ovaries in Barbus grypus of Karoon river and their changes during annual maturation cycle. For this purpose, 120 adult  B.grypus with a mean weight of 835.0 to 1012.0 g, were caught from Karoon river and transferred alive to the laboratory. After biometrical studies, the weights and morphological appearances of...

This study investigated the effect of different photoperiods (14L: 10D, 12L:12D and 10L:14D) on the gonadal development and GtH mRNA expression in the pituitary of damselfish. The results showed that gonadosomatic index (GSI) was significantly lower in shot photoperiod (10L:14D), in comparison with other photoperiodic group during the spawning season. After 60 days treatment, histological analy...

We present and test an extension of the "match/mismatch" hypothesis that attempts to explain the persistence, under conditions of flow alteration, of small, short-lived, native, riverine, fish species. The premise is that flow alteration typically changes environmental conditions, such as temperature and prey abundance, which may affect survival during the larval period of fishes. This "window-...

A total of 48 female spirlins Alburnoides sp. from the Kesselian stream (South Caspian Sea basin, northern Iran) were examined during a period from July 2008 to June 2009 to obtain data on fecundity, and to determine the spawning season of this carp. The mean absolute fecundity of females spirlin was 1722.92 (653.88) eggs. The fecundity has positive correlation with the size of the female. The...

Intraguild predation interactions make fish communities prone to exhibit alternative stable states with either piscivore or prey fish dominance. In the Baltic Sea, local declines of coastal piscivores like perch (Perca fluviatilis) have been observed to coincide with high densities of sticklebacks (Gasterosteus aculeatus). Mechanisms behind this shift between piscivore and stickleback dominance...

Spawning season, recruitment, and growth of the freshwater prawn Macrobrachium lamarrei were studied in a perennial wetland, northeastern Bangladesh during October 2016 to September 2017. season was estimated based on monthly variations percent ovigerous females. Recruitment using time series length-frequency distributions. We compared von Bertalanffy function (VBGF) Pauly Gaschütz (PGGF) ident...

Whole-body morphometrics and 15 nuclear DNA microsatellite loci were analysed for 158 Perca flavescens collected during the spawning season from four spawning locations in central Lake Erie, two along the northern shore and two along the southern shore, to evaluate fine-scale variation (spanning 17-94 km). Results showed significant morphological and genetic differences among P. flavescens from...

The gonadal development of cultured and wild mussels (Mytilus galloprovincialis) was studied in several localities of the Ria de Vigo (NW Spain) from December 1987 to June 1993. In the mussel populations examined, a stable reproductive pattern, with minor variations, was found. Gametogenesis takes place in late autumn and early winter. In late winter, gonad follicles are full of ripe gametes an...

Walleye pollock (Theragra chalcogramma) form persistent midwater and near-bottom schools in the daytime during the winter spawning season in the eastern Bering Sea (EBS). Two spawning areas in the EBS, north of Unimak Island and near the Pribilof Islands, are also the main fishing grounds. To study the schooling pattern of pollock and its impact on fishing behavior on these two fishing grounds,...

In order to obtain data on the reproductive pattern of the clonal cnidarian Zoanthus sansibaricus, polyps were sampled by scuba gear at Taisho Lava Field, Sakurajima, for 24 months between April 2000 and March 2002 (polyps collected weekly for breeding season). According to cross-sections, Zoanthus polyps were divided into three sexual types; male, female and asexual, and were found in the same...