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Migrace jeseterovitých ryb - přehledová studie
GERŽA, Lukáš
In its introductory part, the review study Sturgeon Fish Migration focuses on the introduction to fish migration as such, the systematic distribution of migrations and the main factors influencing migration. As with other migratory fish, the loss of natural habitats and the impassability of watercourses are the greatest threats to sturgeons. Nowadays, there is a great emphasis on sturgeon conservation and rescue projects, either global or regional in scope, are an integral part of this. These are, among other things, the flagship for improving the situation as far as crossing transverse barriers are concerned, thereby improving, restoring and building new functional fish passes, which are also marginally addressed in this study. For proper design and functionality of fish crossings, knowledge of both the biology and ecology of sturgeon fish is required, which are described in detail in this study. This study provides general information on the characteristics of the sturgeon family and focuses on the two genera belonging to this family, which are sturgeon and otter. A large part of the whole work consists of a selection of 11 species of sturgeons, for which reproductive migration, habitat requirements and specific sites (spawning grounds) where sturgeons have historically or currently still naturally reproduce are described.
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Methods of rearing the early stages of sturgeon fishes
KAHANEC, Martin
The review "Methods of rearing the early stages of sturgeon fishes" brings in its introductory part an information on current systematics of chondrosteans. It has recently gone through certain amendments upon the development of genetic mapping the fish populations in open waters, as well as the specimens from fish farms. Owing to worldwide- and long-term reduction of stocks of the last populations of chondrostean fishes in open waters, controlled reproduction followed by progeny nursing is the only one real possibility to save chondrosteans. Reproduction of broodstock with incubation of fertilized eggs in fish hatcheries is relatively well managed but the transfer of swimming-up larvae to exogenic feeding is species-specific and very demanding in this group of fish, and frequently attended by remarkable losses of specimens, namely due to high mortality of early stages of fish. The thesis deals with basic currently performed methods of initial feeding of sturgeons. The respective types of live food and artificial feeds which are appropriate and available on the territory of the Czech Republic, are described in details. Furthermore, the thesis brings description of the basic technological parameters of fish farming facilities and technologies, as well as physical and chemical properties of water, which are the essential part of successful rearing the early stages of fish.
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