Fisheries & Aquatic Life

Heavy metal concentrations in fishes from Zakrzówek Reservoir and the Vistula River near Kraków: Human risk assessment

Ewa Łuszczek-Trojnar — 2024-06-30

The aim of this study was to compare tissue concentrations of heavy metals (copper (Cu), manganese (Mn), iron (Fe), nickel (Ni), zinc (Zn)) in roach (Rutilus rutilus (L.)), chub (Squalius cephalus (L.)), and bleak (Alburnus alburnus (L.)) from two locations on the Vistula River upstream from Kraków and Zakrzówek Reservoir, a former limestone quarry flooded over 30 years ago that is located close to the center of Kraków. The findings showed that heavy metal concentrations in fishes from the Vistula River upstream from Kraków were higher compared to those in fishes from Zakrzówek Reservoir. The highest heavy metal concentrations were found in hard tissues, such as bone and scales, and the lowest was in muscle tissue. Metal pollution index (MPI), estimated daily intake (EDI), target hazard quotient (THQ), and hazard index (HI) analyses showed no significant non-carcinogenic risk to human health from the consumption of the muscle meat of the fishes analyzed. Cancer risk (CR) values, calculated based on maximum Ni concentrations in fish muscle tissue, did not exceed the upper limit of the acceptable cancer risk range. The findings show that the assessment of heavy metal contamination of fishes should be continued and extended to include other water bodies used for fishing and other xenobiotics that accumulate in fishes and may pose risks to human health.

Effect of feed and holding conditions on survival and growth of juvenile crayfish Pontastacus leptodactylus and Faxonius limosus

Katarzyna Kropielnicka-Kruk — 2024-06-30

In the European natural environment attempts are undertaken to replace invasive crayfish species with native ones. For this purpose, aquaculture of crayfish is required, but their behaviour and the lack of balanced feeds impede further development. To effectively eliminate invasive crayfish, more knowledge is needed, in context of their similarities and differences from native species. This study investigates two crayfish species, native Pontastacus leptodactylus and invasive Faxonius limosus in relation to different holding conditions and feeds. Juvenile crayfish were exposed to two types of holding conditions, inside (IN) in tap water and outside (OUT) in water with natural plankton content. In addition, three feeds were tested, sinking chips (F1), flakes (F2) and floating sticks (F3). The feeds composition was similar, but sinking times differed and were quick for F1 and slow for F2 and F3, which provided extended visual and chemical exposure to crayfish. The significant effect of holding conditions on survival was found for both species, with highest results for OUT holding conditions, suggesting important role of natural plankton in survival. Three feeds (F1, F2 and F3), showed no effect for P. leptodactylus but F2 and F3 improved growth in F. limosus, indicating more efficient utilisation of the detected feed.

Effects of selenomethionine on the growth, oxidative potential, digestive enzyme activity, and immune status of juvenile sterlet (Acipenser ruthenus)

Sylwia Jarmołowicz — 2024-06-30

In a 56-day experiment, the effects of selenium-enriched yeast (SeY) on the growth, enzymatic activity of the gastrointestinal tract, oxidative stress parameters, and selected immunological parameters of sterlet, Acipenser ruthenus (L.), were analyzed. The concentration of selenomethionine (SeMet) from SeY in the feed was 0 mg kg^-1 (C), 0.7 mg kg^-1 feed (S1), 1.4 mg kg^-1 feed (S2), and 2.1 mg kg^-1 feed (S3). Statistically significant differences were found in the final fish body weight between the control and groups S1 and S3. A significant increase in lipase activity was found in the initial section of the small intestine of fish from group S3. The highest activity of the antioxidant enzymes glutathione peroxidase and superoxide dismutase was recorded in the liver of fish from group S2. Analyses of non-specific humoral response parameters showed an increase in ceruloplasmin activity in group S1. The lowest active dose of SeMet derived from yeast tested in this study that stimulated humoral immunity and fish growth was 0.7 mg kg^-1 feed (S1).

Spawning biology, breeding, and larval rearing techniques for Xenentodon cancila (Hamilton) for aquaculture and recreational use in Bangladesh: The first approach

Shyamal Kumar Paul — 2024-06-30

The study examined Xenentodon cancila (Hamilton) breeding biology, reproduction, and larval rearing. In this study, gonadosomatic index (GSI) and fecundity were measured for breeding biology every 15 days. Nine doses of common carp pituitary gland (CPG), human chorionic gonadotropin (HCG), and Ovaprim for breeding were administered, except in the control treatment that was without hormones. Mustard oil cake (D1), powdered feed (D2), and one-day-old live tilapia (Oreochromis sp.) larvae (D3) were used to determine larval survival after 28 days. From the end of May to mid-July, the mean GSI value exceeded 15 ± 0.72%, peaking at 16.02 ± 1.28% in June. Mean fecundity ranged from 110 ± 13.34 to 2961 ± 318.57, peaking at the end of June 2019, which indicated that this was the peak breeding season for X. cancila. The best spawning was with CPG at 20 mg kg^-1 fish body weight (BW) and Ovaprim at 1.0 ml kg^-1 BW, but the control group (B) and the group administered 500 IU kg^-1 HCG (H1) did not spawn. Latency and hatching periods were 19-21 and 260-288 h, respectively. The highest fertilization, hatching, and survival rates were 92 ± 4.63%, 69 ± 5.52%, and 66 ± 4.11% with 20 mg kg^-1 CPG (C2), while the next closest value was recorded with 1.0 ml kg^-1 Ovaprim (O2). After 28 days, D3 had the highest survival rate (47.5 ± 4.62%), followed by D2 (31 ± 2.42%), and D1 (18 ± 1.54%). The findings will be useful for hatcheries, fish farmers, the ornamental fish sector, and biodiversity protection.

First report of the presence of Pseudoterranova sp. in the body cavity of salmon (Salmo salar) from the Baltic Sea

Katarzyna Nadolna-Ałtyn — 2024-06-30

Despite salmon (Salmo salar L.) being an important fish in the Baltic Sea ecosystem and its fisheries, knowledge about the parasite fauna of this top predator is scarce. The Anisakidae nematodes (Anisakis spp., Pseudoterranova spp., Contracaecum sp.) found in Baltic Sea fish species are zoonotic parasites that are hazardous to human health. Due to the marked increase in the numbers of grey seal (Halichoerus grypus), the definitive host of Contracaecum sp. and Pseudoterranova spp., increased dispersion of these parasites has been observed in recent years. The aim of our study was to investigate salmon caught in Polish marine waters for the presence of Anisakidae nematodes. Parasitological inspection of the body cavities of 89 individual salmon was conducted in 2012 and revealed the presence of a Pseudoterranova sp. L3 larva. The presence of the parasite is reported here for the first time in the muscle tissue of salmon from the Baltic Sea. The presence of Anisakidae nematodes in commercially important fish species may have implications for human health since these parasites pose a risk of anisakidosis.

First record of stone moroko (Pseudorasbora parva), an invasive alien fish species, in water bodies of urban green areas in Poland

Paweł Wróblewski — 2024-06-30

Invasive alien species are currently a major ecological problem. One such species is stone moroko, Pseudorasbora parva (Gobionidae), which has only been found to date in natural or agricultural water bodies (lakes, rivers and streams, carp ponds). Therefore, the current study is the first description of stone moroko in urban green areas (Warsaw, Poland). The fish were caught with a hydrobiological net. Four catches were conducted in ponds located in Morskie Oko Park (pond 1) and the Saxon Garden (pond 2) – two in fall and two in the spring, while two spring catches were conducted in Dolinka Służewska Park (stream). The population in pond 2 apparently survived the winter, and the fish caught in June displayed visible signs of sexual dimorphism and were significantly larger (average body mass: 1648 ± 1123 mg; range: 460–6090 mg) than those caught in the pond in the two fall samplings (404 ± 122 mg; 154–729 mg). After recording substantial numbers of specimens in the fall, no fish were caught in pond 1 during either of the spring catches, while only a few moroko were caught in the stream in April (1212 ± 869 mg; 454–2901 mg) and none were caught in June. Throughout the study, 59 specimens were caught in pond 1, 74 in pond 2, and 7 in the stream.