No spirlin have been registered in the barbel zone of the Sava River, Croatia in the late seventies of the last century. Since then, due to improved water quality the presence of spirlin gradually increased in number (23.3%) and in biomass (4.7%). The most dominant item in the diet of spirlin were Bacillariophyceae and Chlorophyceae during every monthly investigation. The diet consisted also of invertebrates which can be considered as a secondary or an accidental prey. The size related analyse of the consumed food showed Bacillariophyceae to be preferred food by fish of all sizes. The back calculated growth in the total length could be expressed by the following formula: Lt = 12.0 (1-e -0.59 (t+0.14)). The phi-prime of spirlin from the Sava river is φ’=4.44. The length-weight relationship, covering the fish from the entire growing period, showed an isometric growth with a b-value of 3.025 (p›0.05), except of September when it was significantly allometric. That was confirmed by the non-significant relationship between condition factor and total length (r = 0.014; p > 0.05). However, CF in June, September and October (0.86 ± 0.07; 0.85 ± 0.09 and 0.87 ± 0.10, respectively) was significantly lower (p<0.05) than in May and July (1.00±0.21 and 1.00±0.12, respectively). The improved water quality during the last fifteen years enabled spirlin to migrate and enlarge its population downstream, resulting in a slightly decreased condition factor.
The Neretva chub, Squalius svallize is an endemic species of the Adriatic basin of the southeastern Europe. Altogether, 60 specimens were caught by gill nets from the Neretva river area, the oldest being seven years old. The most dominant item in the diet of S. svallize during winter season were larvae of Trichoptera and Diptera. Diptera larvae were also dominant during spring and summer. In autumn period the largest amount in stomach content were Trichoptera larvae and Gastropoda. Plant material was present in stomach content but not dominant food item. The von Bertalanffy formula, counted from the back calculated growth in total length, appeared to be: Lt = 35.3 (1-e-0.15 (t+1.40)). The phiprime of Neretva chub (ln base) is Φ’=5.23. The length-weight relationship, including the fish from the entire growing period, demonstrated positive allometric growth with a b-value of 3.47. The average value for condition factor was CF = 0.98±0.14 (min = 0.76; max = 1.29).
The ruffe Gymnocephalus cernuus L. is an introduced species in Italy. In order to assess the impact of exotic species on native fish communities, the ecology and biology of intruders need to be thoroughly investigated. The aim of this study was to analyse the growth and reproductive biology of the ruffe population in Lake Piediluco. From June 1999 to March 2002, and between July 2004 and May 2005, 1 330 specimens belonging to seven age-classes were captured. Sex was determined in 385 individuals: 327 females and 58 males. The SL-TL relationship for the whole sample was TL = 0.923 + 1.075SL. The SL-W relationship was W = 0.0154 SL3.102 for females and W = 0.0157 SL3.106 for males. The parameters of the von Bertalanffy growth curve for length using back-calculated SL were L∞ = 218.29 mm, k = 0.27 y -1, t0 = -0.61 for females and L∞ = 161.54 mm, k = 0.32 y-1, t0 = -0.70 for males. The results showed that in Lake Piediluco ruffe grow as fast as in their original environments. Seasonal growth and back-calculation showed the possible existence of differential mortality prejudicial to small specimens. Moreover, growth analysis revealed marked sexual dimorphism in growth in the Lake Piediluco population. Sexual maturation occurred in both sexes at the end of the first year of life. Reproduction occurred mostly in May and June. The mean diameter of eggs was 1.12 mm. The mean number of eggs produced by each female was 11 961, and increased with the size of the specimens; with regard to relative fecundity, an average value of 239 eggs g-1 was observed. This analysis reveals some important biological characteristics of the ruffe that were not previously well known with regard to the Italian population of the species.
The article deals with one type of subordinate clauses expressing causality, namely pronominal-particle clauses in the present Czech. The incorporation of these clauses into the head clause lies in the fact that they express broadly understood causal meanings of adverbial subordinate clauses using primary and secondary prepositions and multiple-word units together with the pronoun to, which anticipates the subordinate clause introduced by the connecting particles že, aby. Data from the Czech National Corpus concerning subordinate clauses of cause (reason), purpose, condition and concession are analysed from the point of view of the Czech language (grammar) system.
Absolute fecundity (Fa) of burbot Lota lota lota females from Lake Haƒcza was 47.3 - 439.8 × 103, the relative fecundity based on eviscerated weight (Fwo) was 617.9 - 1572 × 103, and that based of total weight (Fw) was 44.8 - 1234.5 × 103. Regression equations were calculated, approximating the most significant relationships between fecundity and total body length of burbot (Fa = 0.0138 Sl2.5678, Fa = 0,0099 Tl2.8129) and weight (Fa = 0.6481 W1.0144). Mean gonadosomatic indexes (GSI) increased slightly with body length from 3.9 to 8.8% for females and from 3.7 to 20.6% for males.