The anaesthetic effect of 2-phenoxyethanol onjuvenile Vimba vimba (L.) aged 38-179 days post-hatch (26-56 mm TL) was studied at 25°C. The concentration which anaesthetized 100% of the fish within 10 min without causing mortality after 15 min of exposure ranged from 0.35 g dm⁻³ to 0.48g dm⁻³ in 38 day-old vimba and from 0.33 g dm⁻³ to 0.43 g dm⁻³ in older fish. The induction and recovery times were shorter in the initial phase of vimba juvenile life than in older fish. In fish of the same age, induction time or recovery time did not depend on their size or condition (Fulton's coefficient). At 25°C, 2-phenoxyethanol at 0.40 g dm⁻³ may be used to efficiently and safely anaesthetize vimba juveniles.
The paper reports results of a study on the population of vimba in the Rega River aimed at localisation of the spawning sites and support of the natural reproduction by stocking. The spawning sites were localised with the help of electric catching and the coordinates were determined by GPS units. The fish caught to be used for artificial spawning (145 individuals) were measured (l.t. and l.c.) using an electronic calliper coupled with a PC unit. The sex of the fish was identified and on the basis of scale analysis the age and rate of length and mass increase were estimated. The backcalculation readings were made using the Rosa Lee method. The model of growth was established on the basis of the von Bertalanffy formula. Comparisons of groups of fish were drawn with the help of the nonparametric Mann Whitney U test. Correlations between variables were evaluated by analysis of regression, while the significance of the correlation coefficient was checked by t test. The rate of vimba mass increase was calculated using the modified von Bertalanffy formula was found to be described by Wt = 1215.103[1-e-0.133609(t+0.57322)]2.7559. The spawning sites of vimba localised in the Rega River section between Gryfice and Trzebiatow were concluded to be good sources of spawners for artificial spawning and the number of spawners caught in this section of the river ensures continuation of vimba restitution in the Rega River. The hitherto stocking measures aimed at restoration of vimba population have brought satisfactory results as evidenced by the age structure of the fish caught in the electric fishing in 2008.
In May 2009 parasitic and histoenzymology studies were performed on 22 females and males of vimba bream caught in the Barycz River as part of a restoration program. In a few of the specimens pox-like pathology was noted on the skin. Examinations revealed that these were either caused by a pox virus or the cercariae of Diplostomum sp. Nine genera of parasite were noted to occur in the fish: Myxobolus, Trichodina, Chilodonella, Daktylogyrus, Gyrodactylus, Diplostomum, Posthodiplostomum, Asymphylodora, and Acanthocephalus. Despite the occurrence of various parasites and of localized histoenzymological pathology, the health condition of the specimens of vimba bream examined from the Barycz River was generally good.
Macroscopic and microscopic changes which occur during the annual ovarian cycle of vimba females from the Drawieński National Park (DNP) were studied. The study was carried out in 1997-1998 using 146 fish with an average body length (longitudo corporis) of 24.2 cm and an average body weight of 274.9 g.No abnormalities or pathological changes in the ovaries of the investigated fish were detected. The histological picture showed the clear asynchronicity of oocyte maturation. The following ovary maturity stages, characteristic for portion spawners, were distinguished: IV₂; V₂; IV₃; V₃. A relatively short post-spawning stage was also identified (VI/II). It was confirmed that in vimba from the Drawieński National Park (DNP) the longest the maturity stage is III, which starts in October and finishes in March or April of the next year.
The fecundity of a local, stationary population of vimba bream Vimba vimba (L.) from Lake Ostrowieckie (Oder River drainage area, northwest Poland) was analyzed. The number of eggs in the ovaries was determined by the weight method. The individual absolute fecundity of vimba bream ranged from 9,560 to 157,000 eggs for females measuring from 19.2 to 34.0 cm and weighing from 121 to 693 g. Fecundity varied in the designated size classes from 21 thousand eggs for individuals below 22.0 cm to 104 thousand eggs for the largest ones (longer than 30.1 cm). The average fecundity in the youngest group of females (4+) was 25.6 thousand eggs, while that in the oldest group (9+) was 120.1 thousand eggs. Correlation analysis of absolute fish fecundity versus selected biometric parameters showed a significant dependence.