The contents of 174 stomachs of great cormorants (Phalacrocorax carbo) inhabiting northeastern Poland were analyzed. Fish and hard parts of fish were found in most of the stomachs. (87.4%). Moreover, nematode and tapeworm parasites were observed in 76.4% and 4.6% of stomachs, respectively. Only 1.7% of stomachs were entirely empty. The fish identified in the stomachs were represented by 14 species. The most common species (72.2% frequency) in the diet of cormorants was European perch (Perca fluviatilis L.). Roach, Rutilus rutilus (L.) was the second most abundant prey (30.8%), followed by bream, Abramis brama (L.) (22.6%), bleak, Alburnus alburnus (L.) (16.5%), and vendace, Coregonus albula (L.) (13.5%), while nine other species occurred sporadically (frequencies < 7%). The number of fish species per stomach ranged from 1 to 5 (most often one species), while the number of individuals varied between 1 and 43 (most often 5–10 species). The length (SL) and weight of prey ranged from 4.0 to 62.0 cm and from 0.4 to 721.5 g, respectively. The most specimens were in the size range of 7–9 cm. The smallest specimens were perch and bitterling, Rhodeus amarus (Bloch), while the largest were pike and European eel, Anguilla anguilla (L.). Statistical analysis revealed significant differences in the length and weight of the fish consumed among the most abundant species.
Size frequency, length-weight relationships (LWRs), length-length relationships (LLRs), and Fulton’s condition factor (Kn) were studied in an estuarine fish, Taenioides buchanani (Day), from Hatiya Island in the Meghna River estuary. Specimens were caught with fixed purse nets of two mesh sizes (0.51–1.27 cm and 5.08–6.35 cm) from February to April 2021. The maximum total length of female T. buchanani (37 cm) is a new record for this species. The length-weight relationships (LWRs) for male, female, and unsexed T. buchanani was highly significant (p<0.001), and adjusted r2 values were 0.929, 0.931, and 0.955 for males, females, and unsexed, respectively. The calculated growth coefficients (b) for male, female, and unsexed T. buchanani were 3.087, 3.342, and 3.253, respectively. The length-length equations were TL = 1.1034 SL + 0.8845 (r2 = 0.977) for males and TL = 1.3728 SL + 0.9425 (r2 = 0.975) for females. There were no significant variations in Fulton’s condition factor among the specimens of different length classes (20–37 cm). To the best of our knowledge, no information regarding LWRs or length-length relationships (LLRs) for T. buchanani was previously reported either in the literature or on FishBase. The results from this study can be useful for management and conservation purposes of this mudskipper from the Hatiya Island.
The aim of this study was to assess the species composition and structure of zooplankton and fish communities in lakes with similar ecological conditions that are connected by periodic streams. This was done by assessing the relative importance of local biotic and abiotic interactions associated with the species composition and structure of the zooplankton and fish communities. The study was conducted in three small, soft water lobelia lakes located in the source area of the Brda River, which were characterized by low trophic statuses and similar depths. A total of 15 Rotifera taxa, 18 Cladocera taxa, and nine Copepoda taxa were identified in the lakes analyzed. The lake zooplankton communities differed in species richness, total density, and biomass, while the Shannon–Wiener diversity indexes of the zooplankton communities were similar. Of the three lakes analyzed, the faunal similarity index was the highest in Lake Smołowe. Comparisons of the three lakes indicated there was greater similarity in the pelagic (42.7–50.0%) than in the littoral (20.1–26.8%) zones. The fish community of the three lakes consisted of eight species, and species richness ranged from two to eight fish species. Only perch (Perca fluviatilis L.) and pike (Esox lucius L.) were present in all three lakes. The fish groups also differed in terms of density and biodiversity indicators. Faunal similarity indicators showed significant similarity in the dominance structure of the fish communities.
Ganges River sprat, Corica soborna Hamilton, is an indigenous fish species and an excellent source of animal protein with medicinal values in Bangladesh. Samples from two populations of this fish species were collected from Kaptai Lake and Kirtankhola River in Bangladesh to elucidate their genetic diversity based on Random Amplified Polymorphic DNA (RAPD) analysis. Ten primers were selected for this analysis: OPA-04; OPAL-04; OPA-03; OPF-01; OPG-05; OPG-04; OPA-09; OPAK-04; OPAW-09; OPA-02. A total of sixty-eight bands were found of which thirty-two were polymorphic and indicated a moderate level as 51.07% polymorphisms between these two fish populations. The size of the bands ranged between 200 to 1300 bp in their analysis. Based on the specific primer banding patterns, a maximum polymorphism of 100% was found for primer OPF-01; however, the lowest of 14.29% polymorphism was found for primer OPG-04 for these two populations. The genetic distance and genetic identity of 0.8210 and 0.4400, respectively, also indicated that these two populations were moderately distant from each other. A dendrogram based on Nei’s (1972) genetic distance was constructed using the Unweighted Pair Group Method of Arithmetic Means (UPGMA), and it segregated these two populations into one major cluster C1. Therefore, the present study revealed that these two Ganges River sprat populations are moderately genetically diversified. An effective management program and policy should be undertaken to conserve and manage these indigenous fish species in Bangladesh.
The incidence of diseases has been increasing along with the global production of catfish in aquaculture. Vogesella perlucida has not been recognized as a fish pathogen. This study characterized the V. perlucida associated with diseased catfish, Clarias gariepinus (Burchell), with phenotypic and molecular methods. The ascites of diseased larvae had Aeromonas spp. and Pseudomonas spp. The translucent strain CGB1, phenotypically identified as Pseudomonas sp., was confirmed as V. perlucida with 99% nucleotide similarity. This strain was negative for gelatinase, amylase, lipase, DNAse, and hemolytic activities. No signs of external infection, behavioral abnormalities, or mortality were observed in catfish larvae when immersed challenged at 6.30 × 107 V. perlucida cells mL−1. The results of preliminary in-vitro virulence and immersion assays suggested that V. perlucida had no pathogenic potential to cause disease in catfish. Although the results provided the basic phenotypic and genotypic data on fish-borne V. perlucida (NCBI accession number KJ522788), establishing a host-pathogen relationship at the molecular level was needed to ascertain what kind of relationship this bacterium had with the diseased catfish. Nevertheless, reports on the increasing incidences of Vogesella spp. and V. perlucida with diseased fish in recent years is cause for concern.
A mass mortality event involving cultured blood cockles (Tegillarca granosa) occurred in the Welu estuary in Chanthaburi Province, Thailand, during July and early August of 2013. We collected surviving blood cockles (n = 30) shortly after the mortality event in mid-August and evaluated the physiological conditions of the specimens by performing histological observations of various organs. We found that most specimens of both sexes were at the peak of spawning. Histological observations revealed an absence of food in their digestive ducts and flattened epithelial cells in their midgut glands. The specimens had been experiencing low food availability and nutrient uptake. In addition, rainfall data for Chanthaburi Province revealed that the rainfall in July 2013 was more than twice the average amount received in previous years, and surface salinity data from around the aquaculture site revealed that salinity was < 10 Practical Salinity Unit for longer than a month. Therefore, we concluded that prolonged low-salinity conditions were a major cause of this mass mortality event.
The paper determines two basic parameters of the bream population from the Iskar Reservoir: age structure and growth rate. Material was collected in the fall, spring, and summer months from 2012 to 2016. A total of 174 bream specimens were caught. The analysis of this sample found that 10 age groups were represented. Fish weight from age groups was approximately as follows: from age group 1–5g; 2 – 32 g; 3 – 108 g; 4 – 218 g; 5 – 265 g; 6 – 374 g; 7 – 534 g; 8 – 651 g; 9 – 867 g; 10 – > 1,000 g. The back calculated standard length was as follows: year 1 – 55 mm; 2 – 108 mm; 3 – 161 mm; 4 – 205 mm.; 5 – 230 mm; 6 – 252 mm; 7 – 286 mm; 8 – 296 mm; 9 – 340 mm; 10 – 367 mm. The findings support the conclusion that the linear growth rate of bream from Iskar Reservoir is slower than that of fish from the Danube River basin. Some of the reasons that explain this difference include the dam’s high altitude and the mountainous climate of the surrounding area, which mean the fish growth period is shorter.
The study of the impact of climate change on the fish fauna and fisheries management is a relatively young field of scientific research which has yielded very few analytical studies in the Central and Eastern European countries. This paper is the first attempt to examine the impact of this change on lake fisheries management, made based on an extensive and representative survey addressed at managers and owners of the entities authorised to use these waters for fishing and angling purposes. The conducted analyses enabled the determination of their opinions on the issues of climate change impact on the fish, selected hydrological and biological lake parameters, the possibility of use of fishing gear and its efficiency, the length of angling season, the amount of individual fish species caught by anglers and fishermen, and positive phenomena relating to climate change. Of all the phenomena arising from this change and perceived by the respondents surveyed, the growing population of the great cormorant (Phalacrocorax carbo (L.)), which is exerting increasing pressure on the fishery resources, and conducive to this change, is definitely at the head of the list. As regards the fish species, the pike (Esox lucius L.) is the most vulnerable to this change. The presented results prove that the managers under the study are aware of the ongoing changes and their impact on lake fisheries management, and of the challenges that they will have to face as early as in the coming decades of the 21st century.
Abstract Crayfish catches were conducted using traps in Lake Hańcza, which is the deepest lake in Poland. Two crayfish populations were found to co-exist in the lake: spiny-cheek crayfish (Orconectes limosus Raf.) and signal crayfish (Pacifastacus leniusculus Dana), which is a new species for this lake. Signal crayfish dominated the samples at 98.5% of the specimens caught. The crayfish occurred at depths of 1-10 m. The mean total body length of the male and female signal crayfish (TL) was 99.5 ± 17.8 mm and 96.5 ± 11.7 mm, respectively, while the average body weight (BW) was 38.7 ± 24.9 g and 26.8 ± 9.5, respectively. Chelae were damaged in 4.5% of the individuals. Fishing efficiency (catch per unit effort – CPUE) was 0.96 crayfish trap−1 night−1. Selected characteristics of the population and of individual signal crayfish from Lake Hańcza were compared with those of the two closest neighboring populations of this species in lakes Mauda and Pobłędzie. The confirmed occurrence of the relatively large signal crayfish population in Lake Hańcza excludes this lake as a possible site for native noble crayfish (Astacus astacus L.) restoration.
The first aim of the study was to determine the impact the commercial product S.presso (INVE Aquaculture, Belgium) had on enriching the proximate composition of brine shrimp (Artemia sp.). The second aim of the study was to develop a better enrichment protocol for preparing enriched brine shrimp larvae. Two different enrichment protocols were investigated; the supplement was administered in either one (0.5 g L-1) or two equal (0.25 g L-1) doses. Using S.presso to enrich brine shrimp nauplii with polyunsaturated fatty acids resulted in higher levels of total lipids and higher quantities of docosahexaenoic acid DHA and eicosapentaenoic acid EPA deposition. Additionally, the enrichment supplement did not lead to overall lowered protein content values caused by increased hydrolytic activity that likely facilitates digestion in larval fish as they shift to exogenous feeding.
Abstract In the present study, lysozyme, immunoglobulin M (IgM), and complement component 3 (C3) were measured in unfertilized and fertilized eggs, two week post fertilization (WPF) larvae and 1, 2, 4, 6, and 12 month post fertilization (MPF) juveniles and the female broodstock of Siberian sturgeon, Acipenser baerii Brandt. The lysozyme level was measured with the turbidimetric method and IgM and C3 levels were measured with the ELISA method. The results showed that the lysozyme level decreased significantly from the unfertilized eggs to the 2-week-old larvae, and then it increased until 2 MPF. Significant changes in lysozyme levels were not observed from the 2 MPF juveniles to the broodstock. The IgM level decreased significantly from the unfertilized eggs to the 2 WPF larvae, then it increased until the 2 MPF, and, finally, it revealed a significant decrease in 4 MPF juveniles. Significant variations of C3 were found from the unfertilized eggs to the 2 MPF juveniles. Additionally, there were no significant variations in IgM or C3 in 4 to 12 MPF juveniles or in the female broodstock. The results indicate that two weeks post fertilization can be an immunologically sensitive period in early life stages of Siberian sturgeon.
A comparative study on the nursery culture of the spat of the tropical oyster, Crassostrea iredalei, in an earthen pond and a mangrove canal was conducted over two months. The results revealed no differences in the absolute growth rate determined by shell width between the two culture sites (P < 0.05). Sub-adult oysters cultured in the mangrove canal showed a higher absolute growth rate in shell length and a higher daily growth rate than the oysters cultured in the earthen pond (P < 0.05). The mean survival rate of sub-adult oysters cultured in the earthen pond (99.8 ± 0.2%) was significantly higher than for those cultured in the mangrove canal (66.7 ± 31.4%). Decreased density from the loss of sub-adult oyster nursery culture in the mangrove canal led to higher growth performance than in the earthen pond. However, no difference was found for the fraction of oysters larger or smaller than 5 cm for the two culture sites (P < 0.05). A significant difference was noted in the Condition Index (CI) between the two culture sites (P < 0.05). The high primary productivity in mangroves is a major supporter of higher CI in sub-adult oysters cultured in mangrove canals versus in earthen ponds. Water exchange in the earthen pond to maintain calcium and magnesium concentrations resulted in no differences in the shell compressibility of sub-adult oysters compared with those cultured in the mangrove canal.
Alien fish species are known for the negative impacts they can have on native species and their ability to shape recipient communities. One such case is the North American channel catfish, Ictalurus punctatus (Raf.), in the Arno River in central Italy. During river bank reconstruction, specimens of this species (n=40) were collected, and the stomach content was analysed. As a result, we highlight the opportunistic feeding behavior of this alien species that is responding rapidly to newly available resources and also poses a threat to native species.
The present study aimed to evaluate the feeding performance of juvenile marble goby (Oxyeleotris marmorata) on acidified diets. Five fish meal-based diets at various pH levels (2.5, 3.2, 4.3, 5.3, and 6.0 (control)) were prepared, and each of them was fed to 10 wild-caught O. marmorata juveniles (body length 7.7–9.3 cm; each fish was placed in an aquarium, hence each dietary treatment was in 10 replicates) for 20 days. Throughout the feeding trial, O. marmorata juveniles showed clear increments in the daily ingestion ratio (IR) values of AD 2.5, AD 3.2, and AD 4.3. The control diet and AD 5.3 were almost totally rejected by the fish. On day 20, the IR of AD 2.5 (0.46) and AD 3.2 (0.36) were significantly higher (P < 0.05) than those of AD 5.3 (0.1) and the control diet (0.02). In addition, 70% of fish fed AD 2.5 achieved a high IR value (0.6 – 1.0), and this was the best result among all the treatments (AD 3.2, 60%; AD 4.3 50%; AD 5.3 and control, 10%). These results suggested that acidified diets can be used to wean O. marmorata juveniles, and the recommended pH level was 2.5.
The aim of the study was to determine the impact of different feed rations (0.5, 0.8, 1.1% fish biomass) on the rearing parameters of pikeperch, Sander lucioperca (L.), reared in a recirculating aquaculture system. The study comprised two experiments. In the first, the material used had been sorted by a mean body weight of 35.5 g, while in the second the pikeperch were divided into three size classes: smallest individuals (class S) with a mean body weight of 59.5 g, medium-sized individuals (class M) with a mean weight of 69.3 g, and largest individuals (class L) with a mean body weight of 84.8 g. The experiments ran for 42 days. At the conclusion of the experiments, the highest body weight and length, daily growth rate, and specific growth rate were attained by the group of fish fed the ration of 1.1% of the fish biomass in both experiments I and II. The feed conversion ratio was also the lowest in this feed ration group, and it differed significantly statistically among the experimental groups (P < 0.05). The feed ration of 0.5% of the fish biomass was only sufficient to maintain vital functions, but it contributed only slightly to growth. The different feed rations did not have a significant impact on the final value of the body weight coefficient of variation of the pikeperch reared in the two experiments. The results of the experiment also indicated that pikeperch is a species with weak stock hierarchy and domination structure.
Effluents from a pulp and paper mill in India were analyzed for various physicochemical parameters and heavy metals. Multivariate statistical analysis was used to interpret the data obtained and predict the toxicity of each component to Cyprinus carpio L. fingerlings. The results showed that most of these parameters exceeded recommended levels set by various agencies, and the effluent was not suitable for discharge into agricultural fields or water bodies without further treatment. The results of static renewal toxicity tests revealed median lethal concentrations at 24, 48, 72, and 96 h to be 42, 25, 18.6 and 14.5%, respectively, and the fingerlings exhibited severe behavioral anomalies. The sublethal dose of 2.9% (v/v) caused alterations in the gill and liver at durations of 7, 14, 21, and 28 d. Anomalies such as mucous secretion, leucocyte infiltration, curling of the secondary lamellae tip, clubbing, and the fusion of the secondary lamellae, aneurism, etc. were prominent. The liver showed inflammatory infiltration, cytoplasmic inclusion bodies, vacuolar degeneration, fatty degeneration, pyknosis, karyolysis, distorted pancreatic area, and piecemeal necrosis, among other pathological symptoms. The study concluded that the effluent, even in greatly diluted form, was highly toxic and the severity of responses depended on the length of exposure.
Abstract The objective of the present study was to analyze the morphometric variations of the three presumed taxa within the Barbonymus group, namely B. gonionotus, referred to locally as naleh; B. schwanenfeldii, referred to locally as lampam-A; and Barbonymus sp. referred to locally as lampam-B. The naleh samples were collected from Nagan Raya District, while lampam-A and lampam-B were collected from Aceh Tamiang District, Indonesia. Traditional morphometric characters were measured in 150 fish samples (50 individuals of every taxon). The results of univariate (ANOVA) and multivariate (Discriminant function analysis, DFA) analyses showed that lampam-A and lampam-B have overlapping morphological characteristics, whereas naleh were distinctly different. Therefore, it is presumed that lampan A and lampan B are the same species of B. schwanenfeldii. It was concluded that the morphometric data indicated that there are two species of Barbonymus in Aceh waters, i.e., B. schwanenfeldii and B. gonionotus.
The objectives of this study were to determine the length-weight relationships (LWRs), chelae length (ChL)-width (ChW) relationships, carapace length (CL)-width (CW) relationships, sexual dimorphism, and condition factor (K) of Cherax gherardiae from Maybrat, West Papua Indonesia. The sex ratio of C. gherardiae was found to be 1.04:1. The LWRs for males, females, and all individuals were W = 0.225L1.96, W = 0.181L2.02, and W = 0.187L2.03, respectively. Males and females exhibited negative allometric growth (b<3). There was no significant difference in lengths between males and females; however, the weight of males was greater than that of females. The K values for males, females, and all individuals were 3.17, 3.09, and 3.13, respectively. The ChL of the crayfish ranged from 1.0 to 7.5 cm, and the ChW ranged from 0.4 to 2.5 cm. The CL of crayfish ranged from 1.6 to 6.0 cm, and the CW ranged from 0.6 to 4.1 cm. Males had longer chelae and carapaces than did females. There was no significant difference in chelae width or carapace width between males and females. The ChL-ChW relationships for males, females, and all individuals were ChW = 0.312ChL + 0.260, ChW = 0.397ChL - 0.050, and ChW = 0.345ChL + 0.119, respectively. The CL-CW relationships for males, females, and all individuals were CW = 0.750CL-0.955, CW = 0.526CL - 0.178, and CW = 0.635CL-0.543, respectively.
Changes in the activity of Na+/K+-ATPase, lactate dehydrogenase, and succinate dehydrogenase in the white muscles and gill petals of roach, Rutilus rutilus (L), were studied for the combined actions of water mineralization and water temperature. It was established that decreased mineralization to 260.0 mg dm-3 and increased water temperature to 32°C increased aerobic processes in roach tissues. A sharp increase in water temperature and changes in water mineralization significantly affected the tolerance and physiological state of fish and could impact their abundance in waterbodies.
The present status of freshwater crabs (Decapoda, Brachyura) in Turkey is reviewed in this study, with the purpose of identifying the exact number of species, their conservation status, and their distribution. In previous records, it was reported that Turkey has nine freshwater crab species belonging to the genus Potamon: Potamon bileki Pretzmann, 1971, P. ibericum (Bieberstein, 1809), P. hueceste Pretzmann, 1962, P. persicum Pretzmann, 1962, P. magnum Pretzmann, 1962, P. potamios (Olivier, 1804), P. setiger Rathbun, 1904, P. rhodium Parisi, 1913, and P. mesopotamicum Brandis, Storch & Türkay, 1998. However, there was no detailed information on species distribution in Turkey. This review is intended to update the distribution of species in the country, and it revealed that populations of three more freshwater crab species (P. karpathos, P. fluviatile and P. hippocrate) also occur; thus, there are currently 12 freshwater crab species in Turkey. In addition, this review provides a distribution map and identifies possible threats to each species. This review can serve decision makers in the development of management strategies to better protect the environments of these species that are facing growing anthropogenic impacts.
