The existence of three autochthonous crayfish species is confirmed in the northwest of the Republic of Srpska: Astacus astacus, Pontastacus leptodactylus and Austropotamobius torrentium. There is a lack of information on the European crayfish population status in the Republic of Srpska comparing to other European countries. Our aim is to generate the latest information on crayfish distribution and population status, and make it the basis for managing and preserving natural population. The present study was implemented in the period from April 2018 until September 2019. Mostly distributed crayfish species in the Republic of Srpska is A. torrentium registered in 12 locations at altitude ranging from 201 to 846 m in the Vrbas river basin, but it is also present in the tributary streams of the Sana river, in ecologically-like habitats, in particular in relatively clear waters with low quantity of organic substances (I and II water category). A. astacus is mainly present in the Crna river basin, forming both river and lake population (a great number thereof is present in the Balkana lake) – waters with oxygen concentration over 8g O2 m-3 and with BOD5 values below 0.5g O2 m-3. P. leptodactylus was found only in two locations: The Matura river (in Srbac) and the Vrbas river (upstream from Razboj), in the I-III category waters. The identified possible threats for autochthonous crayfish in fresh water ecosystems of the Republic of Srpska require urgent water management and preservation actions.

Regarded as a protected species on the IUCN list of endangered species, and classified as data deficient species, the stone crayfish (Austropotamobius torrentium) is one of the five European species from the Astacidae family that lives in freshwater ecosystems across Bosnia and Herzegovina. The aim of this study was to investigate the variability of selected morphometric characteristics of male and female crayfish of the A. torrentium species from the upper reaches of the Mlinska River. The crayfish were sampled in June 2021 when 62 individuals (22 males and 40 females) were caught. They were analyzed fresh in the field and in the laboratory. The treatment included the measurement of 12 morphometric features: total body length (TBL), weight (W), claw length (CLL), claw width (CLW), carapace length (CPL), carapace width (CPW), rostrum length (ROL), rostrum width (ROW), abdominal length and width (ABL, ABW) and telson length and width (TEL, TEW). The mean body length ± SD was 79.05 ± 7.35 in males and 60.54 ± 10.03 mm in females. The mean recorded body weight ± SD was 17.51 ± 8.3 g in males and 7.02 ± 4.41 g in females. Using the linear regression method, a positive correlation was found between body length and weight (♂ R2=0.7644; ♀ R2=0.8222), body weight and claws length (♂ R2=0.876; ♀ R2=0.9661), as well as carapace width and body length (♂ R2=0.7216; ♀ R2=0.8411). Using the T-test, a statistically significant difference of the analyzed morphometric parameters was found between the sexes, which is explained by the pronounced sexual dimorphism of stone crayfish. The calculated values for Condition factor and the Crayfish constant indicate that the males are of better fitness, which is in line with the results of previous research in Europe. Data presented in this paper can serve as a basis for further research of A. torrentium in this area.

This paper presents the first information about the morphological variability and sexual dimorphism of the stone crayfish Austropotamobius torrentium in the area of Marjanovića Stream in Čelinac (Republic of Srpska, Bosnia and Herzegovina). The crayfish were caught by handmade made baited traps from October 2018 to May 2019. A total of 67 specimens were caught, out of which 33 males and 34 females. The eight morphometric characteristics-body weight (W), body length (TBL), claw length (CLL), carapace length (CPW), carapace width (CPW), abdomen length (ABL), rostrum length (ROL) and rostrum width (ROW) were analyzed for all specimens and the results were partially matched into the already known range of variations. Also, the body condition was determined for all individuals. By using the t-test, the significant differences between the sexes for W, TBL, CLL, CPW and ABL were registered, which could be explained by the sexual dimorphism of the stone crayfish.

This paper presents the information about morphological variability and sex dimorphism of the Noble crayfish (Astacus astacus) in the area of the Balkana Lake in Mrkonjic Grad. The crayfish were caught by hand made baited traps from October 9nd 2018. until May 31th 2019. A total of 58 crayfish were caught, of which 38 males and 20 females. The eight morphometric characteristics: body weight (W), body length (TBL), claw length (CLL), cephalothorax length (CFL), carapace width (CPW), abdomen length (ABL), rostrum length (ROL) and rostrum width (ROW) were measured, both in males and females. Also, the body condition was determined for all specimens. The results of morphometric characteristics partially matched into the already known range of variations. These data represent first ones for the observed area. The t-test showed that there were significant differences between the sexes in W, TBL, CLL, CFL and CPW which are explained by the emphasized sex dimorphism of the noble crayfish.

Brown trout is a common type of fish grown for consumption in open and flowing fish ponds on the rivers of Bosnia and Herzegovina. We conducted this study during three seasons (spring, summer and autumn) to obtain a complete picture of the morphological and histological characteristics of selected trout tissues. The physicochemical characteristics of the water from the Pliva River near Pljeva and the fish pond where intensive breeding of trout is carried out were analyzed. These analyses have shown that there are no major deviations in water quality and that the water in the pond is of excellent quality. A total of 90 trout were harvested during all three seasons and their morphometric characteristics were determined by analyzing ten parameters. After the dissection of all individuals, histological and stereological analysis was performed to compare the tissues of the liver, stomach, gills and muscles. These analyses showed significant differences in the histoarchitecture of selected trout tissues from the pond compared to the river. Liver tissue had altered hepatocyte shape and presence of adipocytes; stomach tissue had stronger mucosa and weaker muscle layer; gill tissue had lower respiratory lamellae; while muscle tissue had a significant presence of adipose tissue in brown trout living in the fish pond compared to those in the river. All these changes are due to the quality of commercial feed and the inability to move freely.