National Repository of Grey Literature 2 records found  Search took 0.00 seconds. 
Comparison of different ways of breeding, nutrition and controlled reproduction of Lota lota
ZÁVORKA, Milan
Based on the results reached after 216 days of experimentation with various breeding types, it can be said that the type of feed is not of paramount importance. This fact is based on the previous adaptation of submitted food, this is especially important for artificial feed. From our point of view, the more important factor is temperature, intensity and method of breeding. Prey selections choices involving 11 species of fish were performed on age groups of different burbot. All groups of burbot preferred the following species: grass carp, pikeperch, tench and stone moroko. The non-preferred species was ruffe. And different preferences were set for common carp, silver carp, burbot, sunfish and also for roach. The study evaluated reproductive parameters in burbot (Lota lota ) and focused on incubation time in two localities. Burbot spawning was observed from January to early February at an average temperature of 1.55 +- 0.9 °C in Borova Lada and 4.78 +- 0.11 °C in Mydlovary. For burbot at the age of 2+, at an average 1166 +- 100 were determined number of swollen eggs per gram. Relative fecundity was at 257260 +- 70678 eggs per kilogram of female. The absolute fecundity was at 24232 +- 6753 eggs.The last parameter evaluated was the incubation period. The average incubation period in the years 2020-2022 was 202 +- 24.55 °D in Mydlovary and 75.8 +- 16.67 °D in Borova Lada. In connection with artificial spawning, in this study, we further point out the possibility of peeling artificially spawn eggs with NaClO, in which we did not observe a negative effect.
Impact of american mink on stone crayfish populations
PAVLUVČÍK, Petr
1. Impact of introduced American mink (Mustela vison) predation on endangered stone crayfish (Austropotamobius torrentium) was examined in western Bohemian middle-sized streams for two years. Mink diet selectivity and its impact on its prey abundance were been investigating as the main target of this study. 2. The mink diet was described from excrements which were found on the target areas. The importance of different types of prey was specified by their relative numeric contribution to diet. The number of hunted crayfish was elicited from the number of crayfish remains which were collected during two years. The crayfish abundance was determined by capture {--} recapture method. 3. The crayfish was most frequently observed component of mink diet. The rate of mink predation on crayfish was dependent on density of crayfish population. This observed rate was lower during winters than during summers. The mink preferred significantly longer crayfish than was the mean of this value in population. 4. Although the crayfish was important part of mink diet the trend of impact of mink on crayfish is still inexplicit. It would be important to continue in this research to determine correlation between these two species.

Interested in being notified about new results for this query?
Subscribe to the RSS feed.