kutum, rutilus frisii kutum, is an commercially important fish in the caspian sea. the fish enters the rivers leading to the caspian sea for spawning. one of these rivers is shiroud river. in the artificial propagation process of kutum, different factors are involved in quality and quantity of female broods eggs and also in the best temperature and migration time for spawning. the influence of ...

6 One of the most remarkable characteristics of collective motion of fish is the emergence of 7 complex migration patterns in which swimming fish are synchronised by remaining together 8 and moving in the same direction. These migration patterns, referred to as fish schools, are 9 often explained using individual based models (IBM’s) that focus on interactions between 10 single individuals. The...

The objective of this study was to determine the effect of human chorionic gonadotropin (hCG) on sexual maturation, plasma sex steroids (17β-estradiol, E2 and 17α-hydroxy progesterone (17α OHP)) and thyroid hormones (triiodothyronine, T3 and thyroxin, T4) levels in upstream - migrating Caspian lamprey. During the experiment, 36 fish (24 females and 12 males) in  spring 2013 and 36 fish (24 fema...

Migration is a commonly described phenomenon in nature that is often caused by spatial and temporal differences in habitat quality. However, as migration requires energy, the timing of migration may depend not only on differences in habitat quality, but also on temporal variation in migration costs. Such variation can, for instance, arise from changes in wind or current velocity for migrating b...

In terrestrial and aquatic organisms, migration is a very common phenomenon that occurs both on diel and seasonal bases either for, reproduction, feeding or refuge seeking from predators or adverse climatic conditions. Migration is triggers by various extrinsic factors such as, precipitation, water level, current and discharge, lunar cycle, photoperiod, temperature, dissolved oxygen concentrati...

During 12 months of sampling, from 17 stations, 327 specimens of Soboor fish Tenualosa ilisha, including 120 females, 113 males and 86 immature were caught. Total length (TL) of the fishes was 120-500mm. Maximum diameters of soboor ova 0.795mm and the ova with diameter more than 0.7 mm released at one spawning round. Temporal and spatial distribution of ova diameter corresponding to GSI changes...

During 12 months of sampling, from 17 stations, 327 specimens of Soboor fish Tenualosa ilisha, including 120 females, 113 males and 86 immature were caught. Total length (TL) of the fishes was 120-500mm. Maximum diameters of soboor ova 0.795mm and the ova with diameter more than 0.7 mm released at one spawning round. Temporal and spatial distribution of ova diameter corresponding to GSI changes...

Habitat fragmentation is a growing problem worldwide. Particularly in river systems, numerous dams and weirs hamper the movement of a wide variety of species. With the aim to preserve connectivity for fish, many barriers in river systems are equipped with fishways (also called fish passages or fish ladders). However, few fishways provide full connectivity. Here we hypothesized that restricted s...

Various methods have been developed to mitigate the adverse effects of the Federal Columbia River Power System on juvenile Pacific salmon out-migrating through the Columbia River basin. In this study, we found that hatchery-reared spring Chinook salmon Oncorhynchus tshawytscha in the river are in varying degrees of health, which may affect delayed mortality and the assessment of the effectivene...