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The aim of the study was to determine individual absolute and relative fecundity in vendace, Coregonus albula (L.), populations from four Western Pomeranian lakes that differ morphometrically and trophically. The highest mean total length and individual weight were recorded in the fish from the mesotrophic lakes Ińsko (229.1 mm and 106.6 g, respectively) and Miedwie (228.1 mm and 105.1 g, respectively). The highest individual absolute fecundity in particular age groups as well as individual relative fecundity were noted in the fish from Lake Miedwie (6635-24620 eggs per female and 10756-11609 eggs per 100 g female body weight, respectively), while the lowest values of these parameters were confirmed in fish from Lake Glinna (4782-6087 eggs per female and 6406-6953 eggs per 100 g female body weight). A high, statistically significant correlation between absolute fecundity and total fish length and a slightly lower correlation between absolute fecundity and fish age were noted in all of the populations studied.
Data regarding the AluI restriction site polymorphism from a recent study on mitochondrial DNA phylogeographic relatedness of vendace (Coregonus albula L.) populations were re-examined using the coalescent method. Restriction site loss at the AluI recognition sequence was modeled as a mutation, and ancestral information such as time to the most recent common ancestor (TMRCA) and age of the mutation were inferred from gene trees assuming the infinitely-many-sites model of mutation. Coalescent trees were simulated under two evolutionary models using the GENETREE program. One model assumed a panmictic population and the other a subdivided one. The mean values of the TMRCAs did not differ between the two cases and were 2.4; this suggested that the most recent, common ancestor of the present vendace might have lived about 720,000 years ago.
Studies on diet of vendace from the Maróz Lake were carried out to determine sea- sonal changes in food composition in relation to changes of zooplankton food resources in the environment. Fish samples, were collected once a month from April to November in the years 1994–1996. A total of 409 alimentary tracts were analyzed. Simultane- ously, crustacean zooplankton samples were collected to assess food abundance. The occurrence of Cladocera and Copepoda in zooplankton samples from the Maróz Lake. Food composition in the gut of vendace did not correspond with zooplankton abun- dance in the water. Due to considerable oxygen de fi ciency in the Maróz Lake (recorded in water layer 4 m below the surface), especially in June, it may be presumed that sublit- toral or even littoral was the bottom zone accessible for vendace, what, in turn, seems to be indicated by the presence of detritus, algae and macrophytes debris in food of the considered fish species.
Background. Due to its economical importance the vendace has been considered one of the most important items of the ichthyofauna of Polish lakes. This is mainly because of favourable biological features of this species, namely: short (2-3 years) period of attaining market size, relatively fast growth rate, schooling behaviour facilitating catches, and most of all the high meat value, making it a desirable consumer item. Materials and Methods. Biological characters were determined in 451 vendace from Lake Miedwie, caught in spring, (124 individuals), summer (132), late summer (87), and autumn (108). The age and growth rates of the fish were determined based on scales using commonly accepted methods. Fulton- and Clark coefficients were used to determine the fish condition. Results. The fish caught were 180-294 mm-long (TL) and weighed 45.2-176.3 g. Mean values of the Fulton coefficient indicated a pronounced improvement in the fish condition from spring to later summer (0.70 and 0.80, respectively) and a slight reduction in autumn (0.75). The age composition of the fish was as follows: 1+, 213 individuals (47.2%); 2+, 229 ind. (50.8%); 3+, 9 ind. (2.0%). The von Bertalanffy equations that describe theoretical growth of the fish examined in length (Lt) and weight (Wt), were calculated. Conclusion. According to the generally accepted criteria of the vendace growth rate, the Lake Miedwie individuals showed a very good growth, higher than that recorded in populations inhabiting other whitefish lakes of Polish Western Pomerania, which indicates the availability of appropriate food resources for the vendace in the Miedwie.
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