Journal of fish biology最新文献

This study aimed to describe reproductive ecology based on morphological aspects of Peckoltia oligospila in stream rapids, eastern Amazon. A total of 186 fish (75 males and 111 females) were collected. The sex and gonadal maturity stage of these specimens were obtained based on histological characteristics of the gonads. The sex ratio, gonado-somatic index (GSI), relative frequency of the different maturity stages, size at first sexual maturation, condition factor of the population, and fluviometry were evaluated during the study. There was a significant female frequency during the study. The population exhibited positive allometric growth without differences between sexes. GSI and relative frequency showing a reproductive period synchronized in February, and the species exhibited parcelated spawning. L₅₀ was estimated at 5.85 and 7.39 cm for females and males, respectively. There were significant differences in the condition factor only in females that showed a highest value in August. Thus, based on the results P. oligospila has an intermediate strategy between the opportunistic and equilibrium strategies.

The study of aquatic animal movements is a rapidly growing field of research, with tracking methodology ever developing and refining. Acoustic telemetry is arguably the most popular method used to study the movements of fish. Despite this method being able to elucidate many aspects of movement behavior, including residency, home range, and migration, among others, one aspect that remains challenging is the study and definition of connectivity, particularly within marine seascapes. As such, this review assesses published literature on acoustic telemetry studies, which have specifically assessed some aspect of fish connectivity, and discusses these in terms of study distribution and overall trends, the diversity of taxa and life stage assessed, the role that large-scale acoustic telemetry networks plays in assessing connectivity of marine fishes, how connectivity studies have been used in an applied context, and proposes definitions linked to specific types of connectivity, which will assist future researchers when conceptualizing studies. Further, methods that can be used in conjunction with acoustic telemetry to complement the data are discussed. Given that marine resources and habitats are intricately connected, this review highlights the critical role that acoustic telemetry can play in assessing this link. It is envisaged that our developed framework of connectivity definitions will assist future studies and stakeholders in assessing ecosystem functioning and ultimately contribute to improved conservation and management of marine fish populations and ecosystems.

There are gaps in our understanding of sturgeon's response to anthropogenic sounds and the spatial scales at which they occur. We measured spatial displacement of Atlantic sturgeon in the St. Lawrence River at various distances of approaching merchant ships. This fish population is designated as "threatened," although anthropogenic noise is not currently considered a direct threat. For several years, Atlantic sturgeon migrations have been monitored by the Quebec government using acoustic transmitters and a network of telemetry receivers in the St. Lawrence River. We combined fish telemetry data with merchant ship positions to detect co-occurrences between Atlantic sturgeons that remained in the vicinity of the receivers and approaching ships. Numerical simulations reveal that the probability of masking of transmitters (69 kHz) by ship noise was infinitesimal and that the disappearance of the transmitter signal was related to fish movement. When the ships approached, a significant spatial displacement was detected with ships at distances between 0.5 and 5 km from the receivers. After emitter signal loss, over 61% of sturgeons took at least 30 min to be detected again or did not return at all in the vicinity of the receivers. Furthermore, the median time to redetection after a ship transit was longer than when no ship was approaching (31 vs. 18 min). Our results show that sturgeons alter their position due to approaching ships at greater trigger distances than previously documented, which are too far away to be attributed to visual cues alone. We also found that the long-distance propagation of low-frequency sounds from large ships through water should not be heard by Atlantic sturgeon at distances of 1 km and longer based on current knowledge of sturgeons hearing. These results suggest that behavioral responses in Atlantic sturgeons are modulated not only by visual cues but can also be triggered by underwater sounds at relatively long distances, although the precise mechanism is still unknown.

The zebrafish (Danio rerio) model is increasingly popular in neurobehavioral research, and behavioral outcomes are commonly evaluated in studies on neurodegeneration and neurotoxicity. Sex and age have been identified as important variables in cognition studies; however, these factors are often underreported in published studies that use the zebrafish model, leading to uncertainty about their impact in zebrafish T-maze experiments. In this study, we evaluated the role of sex and age in zebrafish cognitive function using a 5-day T-maze task. Our results demonstrated that female and younger zebrafish had increased learning and memory capacity. These findings highlighted the importance of considering and reporting sex and age in experimental design in zebrafish cognitive neurobehavioral studies.

Barbatula nuda is considered a promising emerging species to diversify small cold-water fish aquaculture worldwide due to its rapid growth and delicious flesh. However, limited information on larval development and nutrition is available. In this study, 7-day feeding experiments were performed to evaluate three different initial diets (zooplankton, phytoplankton, and artificial microdiet) in the zoo group, algae group, and AD group on growth, development, and digestion of larvae B. nuda. The results showed that there was no significant difference in survival rate among the three groups (p > 0.05). The algae group exhibited the highest feed intake success rate and body weight (p < 0.05), the best intestinal development with the protruded intestinal mucosa, and visible intestinal microvillus. Pepsase and trypsin enzyme activities in the algae group larvae were significantly higher than those in the other two groups (p < 0.05). Transcriptome data showed that the mechanistic target of rapamycin pathway of B. nuda fed with phytoplankton was activated, and the metabolisms of carbohydrate were significantly more active than those in the other two groups. As omnivorous fish, B. nuda could accept zooplankton, phytoplankton, and microdiet as initial diets with its survival unaffected, but B. nuda fed with phytoplankton exhibited better growth status and digestive tract development and higher digestive enzyme activities than those fed with other two diets. Therefore, phytoplankton was a suitable initial diet for B. nuda. Our findings provide guidance for the artificial breeding of B. nuda and a theoretical basis for research on fish initial diet.

Atlantic salmon is an important aquaculture species that has fascinated naturalists for centuries, resulting in its biology being widely characterized. Certain details about the early development and the inheritance of meristic variation in the post-cranial axial skeleton are, however, largely unexplored. The present study gives a detailed description of the sequence of formation of the post-cranial axial skeleton based on whole-mount staining and used radiology to investigate the inheritance of meristic variation in isogenic hybrid all-male families of Atlantic salmon (~4 kg). Eight different families were created by crossing two homozygous double haploid XX females (dam A, B) with four different double haploid homozygous YY super males (sires a to d). In the caudal fin complex, the first bone to form is hypural 1 and its associated lepidotrichia followed by a bidirectional formation of new bones. In the dorsal and anal fins, development starts in the cranial part, and new bones form bidirectionally towards the head and tail fin. The neural and haemal arches start to form at segment 43, and further development is bidirectional. The first parapophysis form in the caudal part of the abdomen followed by a unidirectional completion cranially. The first ribs form at segment 3 and new ribs develop unidirectional caudally. Chordacentra formation starts at segment 24 followed by formation of chordacentrum number 58 (caudal-most vertebra). New chordacentrae form bidirectionally from segment 24 in parallel with the formation of chordacentrum number 57. The first epineuralia form at segment 1 followed by a unidirectional completion caudally until segment 30. The first supraneuralia to develop is number 10 closely followed by number 1, then new supraneurals form bidirectionally from number 10. Analysis of the inheritance on the post-cranial axial skeletal bones showed a strong maternal effect on total vertebrae centra and tail fin lepidotrichia counts. For these skeletal counts, dam A produced offspring with modes of 58 and 45 respectively, while dam B produced offspring with modes of 59 and 42. The higher number of total vertebrae centra produced by dam B was associated with additional abdominal and/or transitional vertebrae. The completion of formation in different post-cranial axial skeletal parts are either bi- or unidirectional, and the initiation of formation is site specific for each skeletal part with some inter-part similarities. Further, the present results may suggest that there has been a maternally driven selection for more abdominal vertebrae associated with a higher number of total vertebrae, and more tail fin lepidotrichia associated with a lower number of total vertebrae. These changing meristic counts may impact on important fitness-related traits, such as fecundity and swimming ability, making the present findings relevant for both ecological and aquaculture sciences.

Chromis tweddlei, a new species of damselfish, is described from seven specimens, 88.8-111.1 mm standard length (SL), collected during a 2008 expedition by the R.V. Dr. Fridtjof Nansen at 214-219 m depth (an unusually deep occurrence for the genus) on the Cargados Carajos Bank, Mascarene Plateau, southwestern Indian Ocean. Chromis tweddlei sp. nov. closely resembles Chromis axillaris, Chromis pelloura, and Chromis woodsi, the only congeners occurring in the western Indian Ocean (WIO) that share the character of having 14 dorsal-fin spines and a dark caudal band. Chromis tweddlei sp. nov. can be distinguished from its regional congeners by having II,13-14 anal-fin rays, 19-20 pectoral-fin rays, 18-19 tubed lateral-line scales, 4 scales above lateral line to the origin of dorsal fin, 29-32 total gill rakers, and colouration, including a caudal band that tapers anteriorly the full length of the caudal peduncle. A key to the 14 dorsal-fin spine species of Chromis from the WIO is provided.

To clarify the differences between migratory and non-migratory salmonids during the parr-smolt transformation, we conducted experiments on steelhead (SH) and rainbow trout (RT) Oncorhynchus mykiss. We examined relationships among different parameters of osmoregulatory, endocrine, immune, and stress-related regulation in these fish following free selection of salinities. For this, we used an experimental halocline aquarium in which the upper layer was filled with fresh water and the lower with seawater. There was no significant difference between the two trout strains in terms of the number of fish in the final positions after the overnight trial. However, the time spent by each fish in the lower tank during the overnight trial was significantly longer in SH than in RT. Additionally, the time spent by each fish in the lower tank and plasma cortisol concentration were significantly correlated in RT, but not in SH. Similarly, plasma osmolality after the trial had a significant positive correlation with plasma cortisol concentration in RT, but not in SH. The plasma cortisol and mRNA levels of sodium-potassium ATPase-α3 in the gill were negatively correlated, as were several types of cortisol receptors in the gill and brain, in RT. Meanwhile, the genes expressed in SH were positively correlated with plasma cortisol. In SH, plasma cortisol was also significantly correlated with immune and stress-related factors, which was not seen in RT. Our results suggest that the studied factors are important to behavioral and physiological differences in anadromy among salmonid species.

This study investigated the impact of an oxygen-rich spray on rainbow trout subjected to short-term air exposure episodes. These episodes can be due to sampling procedures or catch-and-release (C&R) practices, focusing on behavioral, haematological, and physiological responses. For this, 12 rainbow trout were divided into two groups: control and oxygen-rich sprayed fish. The fish were chased for 3 min and exposed to air for 6 s, and blood and behavior parameters were assessed. Simulated C&R resulted in partial physiological reflex impairment across groups. However, sprayed fish exhibited significant differences during recovery in head complex reflex and faster tendencies to regain orientation compared to control. Haematological analyses revealed that the treated group displayed reduced erythrocyte swelling and maintenance of red blood cell (RBC) counts, indicating reduced need for compensatory responses to hypoxia. Meanwhile, stress-related indicators, including cortisol, glucose, and lactate, remained unaffected by the treatment, suggesting no interference of spraying with the fish ability to launch a healthy stress response. No adverse effects were observed on skin surfaces or gills after an exploratory analysis. Overall, the oxygen-rich spray exhibited favorable effects, indicating potential benefits in protecting rainbow trout during C&R practices or sampling episodes. Moreover, there is a possible wider application of this methodology to benefit other species of fish subjected to stressors such as aquaculture, research, and fisheries management.