Abstract. This study investigated the effect of partially replacing fish meal (FM) in diets with plant protein ingredients on the growth, feed intake, feed efficiency, and nutrient retention of Siberian sturgeon, Acipenser baerii Brandt, juveniles. FM was replaced with soy protein concentrate (SP) and rape meal (RM). Three experimental feeds (40% crude protein, 10% fat) were prepared by extrusion. The protein sources in diet FM were fish meal, blood meal, and fish hydrolysate. In diet SP, the fish meal and fish hydrolysate were substituted with soy protein concentrate, and in diet SP-RM, with soy protein concentrate and rape meal. Each diet was fed to triplicate groups of sturgeon with a mean initial mass of 14 ± 1.3 g. The growth test lasted for 50 days, and were carried out in flow-through tanks of 600 dm 3 capacity. The sturgeon from group FM reached an individual body weight that was about 10% higher than that of the fish from the other dietary variants; the significance of the differences was confirmed statistically (P < 0.05). The specific growth rates (SGR) were similar during the growth test (about 4% d -1) and did not differ significantly. The feed conversion (FCR) and protein efficiency (PER) ratios were not significantly affected by the different dietary treatments, and were about 1.2 and 2.1, respectively. The proximate composition of the sturgeon bodies was similar, except with regard to lipid content. Protein retention, which ranged from 29.5 to 33.2%, was higher in groups SP and SP-RM. Lipid retention was the lowest in the SP-RM group. The results indicated that soy protein concentrate and rape meal are sufficient partial fish meal substitutes in feed for sturgeon juveniles.
The study of fish ponds have confirmed the presence of nine new locations of Anodonta woodiana in Poland, with strong and vital populations. These are examples of Chinese pond mussels accidentally introduced along with fish imports. Comparison of known localities shows that more mussels are in eastern Poland, from which the migration path of A. woodiana progresses. Most often mussels settle in larger water reservoirs with elongated shapes. Older and longer mussels occur in deeper fish ponds. Moreover, the further south the location, the higher biomass can be obtained.The average age of mussels in a fish pond depends on its bed type and depth; however the latter has less influence. New locations of this species are also to be expected due to deliberate
In the year 2008, studies on ichthyofauna were carried out in the Kończak stream. The stream was divided into four sections representing the variability of the water course. In each section, a research segment (100-150 meters long) was defined. In the ichthyofauna structure analysis, the indices of quantitative biocenotic domination and biomass were used. Furthermore, on the basis of the obtained data, the Shannon-Wiener indices of species diversity (H), as well as the abundance and the biomass (ABC index) were calculated. Altogether, in all research localities, 667 fish specimens were collected, with a total weight of 8,760 g and classified into 19 species. The caught fish were classified into 8 reproductive groups. Significant differences in the species composition and the number of fish were recorded between the particular sections. The number of species occurring in the studied sections oscillated between 2 and 17. The richest ichthyocenoses were recorded in the transitional and forest sections characterized by a comparatively small transformation of the habitats and good environmental conditions. In the remaining two sections, located in the middle and in the upper stream course, there was a distinct impoverishment of ichthyocenoses caused by the decreased attractiveness of the habitats.
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