Journal of Applied Ichthyology最新文献

Length-weight relationships (LWR) were described for 53 species of shallow-water fish caught with bottom trawls in a depth range between 7.3 and 108.1 m during September 2013 in the Colombian Caribbean Sea (fishing area 31 of the FAO). A linear regression was performed using the logarithmically transformed data to calculate a and b coefficients and their 95% confidence interval of the LWR for 53 fish species corresponding to 28 families and 44 genera. Six fish species showed a maximum total length greater than that reported in FishBase: Astrapogon alutus (102.00 mm), Eucinostomus harengulus (162.00 mm), Haemulopsis corvinaeformis (293.00 mm), Cyclopsetta chittendeni (390.00 mm), Etropus crossotus (224.00 mm), and Bairdiella ronchus (415.00 mm). A total of 24 species (45.3%) exhibited isometric growth, 21 species (39.6%) negative allometric, and 8 species (15.1%) positive allometric. This study shows the first estimates of LWR for 25 species of shallow-water fish in the Colombian Caribbean Sea. We found interdependence of growth parameters as a function of fish body shape. The analysis of the relative condition factor indicated that 21 fish species (39.6%) showed poor growth conditions. The results obtained from this study contribute to fill information gaps on shallow-water fish populations and also help fisheries scientists in future population assessment studies in the Colombian Caribbean Sea.

A 50-day feeding trial was conducted to investigate the effects of feeding rates (FRs) on the growth, feed utilisation, and body composition of Brachymystax lenok. Juveniles of B. lenok (initial body weight of 7.6 ± 0.2 g) were fed a commercial diet at the different FRs of 1, 2, 3, 4, and 5% of their body weight. The results indicated that weight gain (WG) and specific growth rate (SGR) were first increased and then decreased with an increase in the FR. The WG and SGR of the 4% group were 299.78% and 3.96%, respectively. The feed conversion ratio (FCR) and protein efficiency ratio (PER) were also significantly affected by the FR (P < 0.05). Furthermore, the condition factor (CF) did not differ significantly among the treatment groups (P > 0.05). However, the FR significantly affected the hepatosomatic index (HSI) and visceral somatic index (VSI) (P < 0.05). With an increase in the FR, the moisture content of the fish decreased, but the ash content changed irregularly. The protein content increased significantly with increasing FR (P < 0.05). The lipid content showed a trend similar to protein in the body. Based on the SGR and FCR data, the optimal FR range was 2.4 to 3.1% for B. lenok (7−30 g body weight) at a water temperature of 16°C.

Endocrine disruptors in marine environments represented by estrogens lead to reverse health phenomena. To obtain a more effective way to reflect and detect environmental estrogens pollution, a method was developed to obtain the full-length cDNA coding vitellogenin gene in B. sinensis, induced by 17β-estradiol (E2) solution. We have downloaded 16 fish gene sequences from the NCBI database and designed PCR primers accordingly. Based on the quantitative real-time PCR method (qRT-PCR), we analyze the differences in gene expression under the conditions of different E2 exposure times in the low, middle, and high-dose groups. The full-length cDNA consists of 4738 nucleotides with a reading frame encoding 1540 amino acid residues. In vitro recombinant plasmids were constructed and transferred to E. coli BL21 for vitellogenin expression. Efficient fusion expression was obtained by IPTG at 16°C, and the expressed target protein (680 amino acids, 75 kDa) existed in a soluble state, accounting for more than 25% of the total soluble protein. We prepared monoclonal antibodies using established immunohistochemistry to detect vitellogenin expression sites in sexually mature female fish. Our study shows that the expression sites of Vg in sexually mature female fish are mainly distributed in the fishtail, hepatopancreas, intestine, muscle, ovary, and pronephric kidney. In conclusion, the vitellogenin from B. sinensis could be used as a biomarker of environmental estrogens to achieve rapid detection in the marine environment and the subsequent experiments of development in colloidal gold strips after this research would be established to provide a highly efficient and convenient detection method for environment pollution.

Allis shad Alosa alosa hatches and develops in freshwater before migrating to the sea during its first months of life. Some field research works dedicated to the diet of the species in freshwater put forward that young stages of allis shad feed mainly on zooplankton, being opportunistic and euryphagous; their diet would diversify through ontogeny in relation to growth. However, these assumptions have never been confronted to the availability of prey, and the exact age of fish was unknown. In this work, we reared young allis shad under seminatural conditions, from 6 to 10 days posthatching until nearly 3 months old, in a trophic environment representative of a natural river. The rearing structures were designed as artificial rivers, supplied continuously by natural riverine water and zooplankton prey. Additional zooplankton was produced in separate basins and added daily in the structures. One artificial river was used to rear allis shad in 2018, and the experiment was conducted on two allis shad batches in 2019 (one batch per river). We described the nekton communities of potential prey available for allis shad in the rearing structures by sampling the water every week, and we compared these data with the stomach contents of fish captured at one and two months old posthatching to describe their diet and prey selectivity. Our results suggest that young allis shad should not be considered as opportunistic in their feeding, since clear selectivity was observed at both ages. One-month-old allis shad highly selected cladocerans, probably because they are easy to catch for fish at this age, when their swimming abilities are limited. Feeding selection at two months old drifted towards other prey taxa (dipteran larvae, ostracods, and/or copepods), whereas cladocerans were no longer preferred. Our results suggest that fish density and competition may entice two-month-old allis shad to enlarge their diet to other taxa, including benthic organisms, while one-month-old fish do not seem able to shift their diet and would fast in the absence of cladocerans. Thus, this highlights that the feeding of young allis shad may be highly challenging during their first month of growth.

Pearl perch (Glaucosoma scapulare) are endemic to the east coast of Australia and have a long history of exploitation. Recent stock assessments indicate that the current rate of fishing mortality is unsustainable in the long term. To better inform the management of the pearl perch stock and to address gaps in our understanding of their reproductive biology, we investigated patterns in gonad development and estimated length- and age-at-maturity and batch fecundity from females collected from southern and central Queensland waters between 2018 and 2022. The mean gonadosomatic index (GSI) varied both temporally and spatially, with maxima in the austral autumn in southern Queensland and in summer in central Queensland, coinciding with sea surface temperatures between 25.26 and 26.32°C. The length- and age-at-maturity of females were 353 mm (fork length, FL) and 4.42 years, respectively, and batch fecundity (B) was correlated to FL such that Ln(B) = 2.45 × Ln(FL) + 3.90. Our results will inform a management strategy to recover the stock to acceptable levels of exploitation.

Hypancistrus zebra is a Loricariid endemic to a very limited stretch of the Xingu River and has a high value in the ornamental fish trade. The natural populations have experienced high fishing pressure since the late 80s and were recently impacted by the construction of the third largest hydroelectric dam complex in the world, the Belo Monte Project. Since 2004, it has been considered critically endangered and had its capture and trade forbidden. Even with its capture and trade prohibited since 2004, the species continues to be one of the most trafficked fish in the world. The biometric knowledge of the species is essential for monitoring its natural populations and management in ex situ environments. This work aims to establish the weight-length relationship (WLR) and length-length relationship (LLR) of the species and to evaluate the condition factor (K) of H. zebra rescued from trafficking. The study was conducted at the Laboratório de Aquicultura de Peixes Ornamentais do Xingu from February 2022 to June 2022, estimating the parameters of WLR and LLR of 1165 specimens divided into four simple linear regression (SLR) models: all specimens, only juveniles, only females, and only males. The K of 190 specimens rescued from trafficking by the Brazilian Federal Police was evaluated. The WLRs and LLRs were estimated using SLR. The difference between the allometry coefficients (b) and between the residuals of the models (juveniles, females, and males) was evaluated using the ANOVA significance test. The total length of the species ranged from 1.6 to 9.3 cm. The coefficient of allometry (b) of the WLR of the species is 3.22 and of the LLR is 1.04, demonstrating that H. zebra presents positive allometric growth. The evaluation of the residuals of the models showed differences between ontogenetic stages and between sexes. The development of juveniles is isometric until the first sexual maturation phase and differs in negative allometric for females and positive allometric for males, showing sexual dimorphism in the species. Among the specimens rescued from trafficking, 54.74% were underweight, and 13.16% were under 60% of the expected K value, demonstrating the poor conditions in which these animals are transported by trafficking.

The genetic diversity of Taenioides cirratus was investigated on the basis of mitochondrial cytochrome c oxidase subunit I (COI) and cytochrome b (Cytb) gene sequences. A total of 159 specimens collected from the Chaohu Lake (CL), Nansihu Lake (NL), Taihu Lake (TL), Pearl River (PR), and Nandu River (NR) were sequenced. The total length of the sequence was 2485 bp with 412 polymorphic sites. A total of 73 haplotypes were identified, with Hap1 being the most widely distributed. The PR and NR populations showed high genetic diversity, while the CL population showed low genetic diversity. TL and NL showed high haplotype diversity but low nucleotide diversity. The analysis of molecular variance demonstrated that the sequence variations were mainly occurred among populations. T. cirratus populations are declining, and rare alleles are present at low frequencies, as analysed using a neutral test and a mismatched distribution analysis. There was a relatively high level of genetic differentiation among the populations of the Yangtze River basin (including NL), PR, and NR (Fst > 0.15). The two similar phylogenetic trees constructed by the maximum likelihood (ML) and Bayesian inference (BI) methods presented three major lineages, of which lineage II contains haplotypes from PR and NR, lineage III contains haplotypes from CL, NL, TL, and PR, whereas lineage I contains only a portion of haplotypes from NR. Based on the neutral test, mismatch analysis, and Bayesian Skyline Plot (BSP), geological and climatic events were inferred to have played an important role in the historical dynamics of T. cirratus population. Hap1, Hap25, and Hap58 were inferred as possible ancestral haplotypes by network analysis. Our study offers an essential foundation for resource preservation and additional taxonomic clarification of T. cirratus.

The study provides the length-weight relationships (LWRs) for eight fish species, viz. Hemiculter bleekeri, H. leucisculus, Opsariichthys bidens (Xenocyprididae), Carassius auratus, Cyprinus carpio (Cyprinidae), Pseudorasbora parva (Gobionidae), Acanthorhodeus chankaensis, and Rhodeus ocellatus (Acheilognathidae), in the world’s largest water diversion project, namely, the middle route of South-to-North Water Diversion Project (SNWDP). Fish specimens were sampled by benthic fyke-nets, gillnets, multimesh gillnets, and electrofishing equipment seasonally from 2015 to 2020. The coefficient of determination (r²) was ranging from 0.964 (R. ocellatus) to 0.986 (H. leucisculus), and the b values for the eight species were within range of 2.5–3.5. Also, our study updates the information on the maximum total length for four species (H. bleekeri, H. leucisculus, A. chankaensis, and O. bidens).

Estimation of the heritability for a given phenotype would provide basic information for potential breeding programs. As one of the most precious common carp strains, Yellow River carp was subject to selection for fast growth and a slender body to meet market demands. In the present study, heritabilities for body shape (body length, BL and body height, BH) and body weight (BW) were estimated based on a molecular parentage assignment for 750 progenies from 58 half-sib and full-sib Yellow River carp families. Eight highly polymorphic microsatellites were used for the construction of the molecular pedigree, and the average observed heterozygosity (H_o), expected heterozygosity (H_e), and the polymorphism information content (PIC) were 0.841, 0.792, and 0.763, respectively. All 750 progenies were successfully assigned to single parental pairs with 100% accuracy. Using the linear mixed model, the heritabilities were estimated to be 0.268, 0.338, and 0.340 for BL, BH, and BW, respectively. High phenotypic (0.831–0.927) and genetic (0.952–0.987) correlations among these three traits suggested that selection for BW could also largely affect the body shape and vice versa. Moderate heritabilities and high genetic corrections revealed by this study strongly indicate substantial potentials for genetic improvement of both growth rate and body formation in Yellow River carp breeding programs.

Understanding drivers of recruitment variation in fish populations requires research conducted on early life stages. Examination of fish otoliths provides useful information for estimating hatching dates, growth, and survival rates of larvae and for investigating the relationship between early life stage phenology and variation in environmental factors such as climate and food availability. In the Laurentian (i.e., North American) Great Lakes, significant reductions in the number of young (ages 1–4 years) lake whitefish (Coregonus clupeaformis) recruiting into the population and commercial fishery have raised questions about factors affecting growth and survival of the larval life stage. Here, we investigate the utility of using otoliths to estimate the age and growth of larval lake whitefish. We raised offspring of wild-caught parents from Lake Simcoe (Ontario, Canada) in a hatchery environment and analyzed otoliths of these known age fish for 75 days posthatch. We further examined otoliths of wild-sampled larvae and age 0 lake whitefish from Lake Huron. We found a strong linear relationship between known age and number of postcheck increments on the otolith and between growth of the otolith and fish length. Increments formed at nearly 1 (0.9) per day beginning at day 20 after hatch. Check and subsequent increment formation was associated with disappearance of the yolk sac. Wild fish had more prominent checkmarks and grew slower than hatchery fish. Thus, otolith analysis represents a promising tool to examine dynamics of early life stages of lake whitefish, although further research is required on the effects of environmental conditions on otolith microstructure.