Journal of fish biology最新文献

The lamprologine cichlid genus Telmatochromis was long considered primarily lacustrine and endemic to Lake Tanganyika until an undescribed Telmatochromis species was reported from the Lufubu River (Lake Tanganyika drainage, Zambia). A phylogenomic study in 2021 confirmed the association of Telmatochromis sp. "lufubu" with Telmatochromis along with another riverine species, Neolamprologus devosi (Malagarasi drainage, Tanzania). Here, we quantify the morphological diversity of the genus Telmatochromis and the two associated riverine species using a multivariate dataset combining geometric and classical morphometrics, as well as meristics. We identify three distinct morphological clusters: the "Telmatochromis vittatus complex" with highly elongated bodies and short heads, the "Telmatochromis temporalis complex" with deeper bodies, and the two riverine species with intermediate body elongation and large heads. Further, we formally describe the species endemic to the lower Lufubu River as Telmatochromis salzburgeri sp. nov. and reassign N. devosi to Telmatochromis. Telmatochromis devosi comb. nov. differs from all congeners by the absence of bi- and tricuspid teeth in the inner tooth rows of the oral dentition. T. salzburgeri sp. nov. can be distinguished from all other Telmatochromis species by a prominent orange stripe along the base of the dorsal fin and from T. devosi comb. nov. by the relatively smaller size of the lower pharyngeal jaw. Both riverine species differ from all lacustrine Telmatochromis by a lower number of dorsal-fin spines. Additionally, the riverine species can be distinguished from the T. vittatus complex by having larger heads and longer oral jaws, and from the T. temporalis complex by their lower relative body depth. With the inclusion of new riverine members, the genus Telmatochromis is revealed to be more morphologically and ecologically diverse than previously recognized.

With the expanding global population, interest has increased in the sustainable aquaculture development of indigenous fishes. In Hawai'i, the brassy chub, Kyphosus vaigiensis, has drawn interest as a candidate species for production. However, little is known about its resilience in aquaculture settings where fish are exposed to acute, husbandry-related stressors. To address the response of brassy chub to handling stress, we characterized the effects of simulated netting and confinement stress on physiological parameters indicative of the alarm and resistance phases of the stress response over a 24-h time course. Specifically, we measured plasma osmolality and glucose, mucous cortisol, hepatic activity of the antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPX), and hepatic lipid peroxidation (LPO). Plasma osmolality in stressed fish was increased relative to controls at 1 and 6 h. Mucous cortisol levels were transiently increased in stressed fish at 1 h following handling stress. In stressed fish, plasma glucose was generally increased from 1 h to 24 h relative to controls. By contrast, SOD activity decreased in stressed fish at 6 and 12 h, returning to control levels at 24 h; GPX activity and LPO were unaffected by the handling stressor. The transient and modest responses of mucous cortisol and antioxidant enzyme activity indicate the recovery of brassy chub from handling stress. Moreover, the sustained increase in plasma glucose and lack of change in LPO suggest mobilization of energy and long-term resiliency toward handling stressors.

Due to the logistical and financial challenges in studying migratory marine species, there is relatively limited knowledge of the reproductive biology, behavior, and habitat use of many ecologically important marine megafauna species, including the Atlantic tarpon Megalops atlanticus. Here, we present a novel observation using consumer-grade aerial drones to observe, quantify the scale of, and classify behaviors within a previously unreported tarpon aggregation (N = 182) over the course of a 2-day fish aggregation event. After the event, we analysed and compared observed behaviors (e.g., cruising and clustering) with those of other fish species with well-documented reproductive behaviors, revealing behaviors potentially consistent with courtship, leading us to believe this to be a possible spawning aggregation or aggregation of reproductive/migratory significance. This aggregation occurred in highly altered and urbanized habitat off the coast of South Florida, during the winter, and outside of tarpon's previously reported spring and summer spawning season. Although few studies to date have used drones to monitor teleosts, this study reinforces their potential value as a tool for monitoring fish populations, behavior, and movement.

The spurdog (Squalus acanthias Linnaeus, 1758) is a globally distributed squaliform shark that has historically been overfished but is now recovering in the northeast Atlantic. Data series on spurdog movement and habitat use have been somewhat limited to research surveys due to challenges associated with electronic tagging. Here, we offer a revised attachment method for externally attached pop-up satellite archival tags that was successful in long-term deployments on pregnant females. Twenty-one spurdogs were tagged in two fjord systems in western Norway for an average of 243 days and provided new details about their behaviour, demonstrating affinity for coastal habitat based on the pop-up locations and recovery positions of the tags (84% within 40 km from tagging location), and depth-temperature profiles. It is likely that parturition therefore occurs in these coastal waters, making them important to the life cycle of this species. The realized depth niche of tagged individuals suggested that surveys may miss sharks if they do not cover the full water column because the sharks used large parts of the water column and spent much time in shallower waters, albeit with seasonal variations (deeper and shallower in winter and summer, respectively). Adoption of this tagging method and combination with movement data from acoustic transmitters will help to better resolve the behaviour of this species as it transitions from a species at risk to a managed fishery. Such studies will provide a more comprehensive understanding of the species' habitat requirements that will empower better informed protections against a return to the red list of threatened species.

Fish presence in tailraces is a remarkable management concern in operating hydroelectric power plants (HPP) in Brazilian rivers. Fish get blocked during upstream migration for spawning, and large shoals can last for days in the tailrace; however, the circumstances that attract fish throughout the year to this region are uncertain, especially during drought conditions. To unravel this uncertainty, we modeled the relationship between Pimelodus maculatus abundance and environmental and operational variables (N = 26) in monthly fishing campaigns at the Machadinho HPP (N = 18). A generalized additive model was fitted to fish abundance in which water conductivity, 30-day accumulated precipitation, reservoir inflow, and seasonality explained 93% of the deviance. It was found that abundance decreased as water conductivity increased, but abundance was higher in summer. However, winter showed the highest abundance in the entire rainfall range with peaks between 130 and 150 mm and above 250 mm. An increase in reservoir inflow decreased fish abundance. During droughts, our findings suggest that the powerhouse foundations, particularly the draft tube, may serve as refugia to P. maculatus.

This study investigated the effects of pre-experimental fasting for 2, 7, and 14 days under both unsheltered (12 h dark-12 h light) and sheltered conditions on the critical swimming speed (U_crit) and oxygen consumption (MO₂) of juvenile grass carp, using a modified swim respirometer. Key findings include (1) the U_crit of test fish decreased significantly, by 28%, after fasting for 14 days and sheltering intensified the impact to a 43% decrease, and (2) fish anaerobic capacity decreased after 7 days but increased after 14 days, and was enhanced by sheltering conditions. These findings are important as they indicate that fasting and sheltering can impair grass carp survival and disrupt river ecosystem balance, highlighting the need for habitat conservation.

Fish visceral waste, which is normally discarded, is considered one of the richest sources of proteinases with potential biotechnological applications. For this reason, alkaline proteinases from viscera of Argentine hake Merluccius hubbsi, Brazilian flathead Percophis brasiliensis, Brazilian codling Urophycis brasiliensis, and stripped weakfish Cynoscion guatucupa were characterized. Individuals were caught by a commercial fleet off the coast of the Argentinean Sea. The intestine and pyloric caeca were dissected out and then minced and triturated with distilled water. The proteinase activity of P. brasiliensis extracts was enhanced by all the ions tested (Mn²⁺, K⁺, Na⁺, Ca⁺²) while the enzymes of the other species were stable in the presence of those ions, retaining more than 60% of their enzymatic activity. Alkaline proteinases of all species showed extreme stability to 5% v/v surfactants at 60 min (Sodium dodecyl sulfate, Triton X-100, Tween 20, Tween 80), and relative stability toward an 6% v/v oxidizing agent (H₂O₂) and organic solvents 80% (acetone, isopropanol, methanol, ethanol). The enzyme extracts were incubated for 60 min with these compounds. Interestingly, alkaline proteinases from all species were compatible with the commercial detergents (Ala, Skip, and Ace). These results demonstrate that proteinases recovered from a no-cost sample such as fishery residues can be used for industrial applications, such as detergent formulations.

The diamond stingray (Hypanus dipterurus) is a species of cartilaginous fish that, according to the IUCN, is globally in a vulnerable state of conservation and its populations show a decline. New records of this ray species in southern Peru and northern Chile have expanded their known range. The species is distributed in the Eastern Central Pacific, from southern California to San Andres, on the central coast of Peru, but is poorly known in Chile. Angler records mined from social media and historical data confirmed the presence of H. dipterurus along southern Peru and northern Chile, extending southward over 1250 km. A species distribution model (SDM) based on previous global occurrences combined with oceanographic layers was built to identify areas of potential and undocumented presence of H. dipterurus. The SDM showed high accuracy (area under the curve = 0.95) and predicted the potential presence of H. dipterurus along vast areas of the Peruvian and Chilean coasts, where the presence of the species was poorly documented. Comprehensive surveys are required to understand the distribution, population dynamics, habitat requirements, and threats to effective conservation efforts in the southern region of its distribution range.

The study investigated the potential alleviating effect of sodium butyrate (SB) on intestinal injuries caused by glycinin in the diet of common carp. Fish were divided into six groups: a control group (without glycinin and SB), a Gly group (with glycinin), and four groups supplemented with different doses of SB (0.75, 1.50, 2.25, and 3.00 g/kg) based on the Gly group. All diets were isonitrogenous and isoenergetic, and the fish were fed these diets for 8 weeks. The results indicated that glycinin activated the mitogen-activated protein kinase (MAPK) signaling pathway, leading to upregulating ERK, JNK, and p38 gene expression in the intestine. However, SB2 and SB3 groups were able to inhibit this pathway. Furthermore, glycinin upregulated the expression of proapoptotic genes (Bax, Caspase-3, Caspase-8, and Caspase-9) while downregulating the antiapoptotic gene Bcl2. The SB2 and SB3 groups were found to alleviate glycinin-induced apoptosis. Additionally, dietary glycinin significantly decreased the expression of tight junction genes (ZO-1, Claudin3, Claudin7, and Occludin1) in the intestine, whereas the SB2 and SB3 groups improved intestinal barrier function. Glycinin also elevated serum levels of d-lactate, diamine oxidase, serotonin, and endothelin, resulting in intestinal damage and increased permeability. In contrast, the SB2 and SB3 groups reduced these serum levels, thereby regulating intestinal permeability. Moreover, glycinin disrupted the intestinal morphology, which was mitigated by the SB2 and SB3 groups by increasing the height and width of intestinal villi folds. Lastly, dietary glycinin altered the intestinal microecological balance by increasing Proteobacteria abundance and decreasing Clostridium and Bacteroidetes abundance. The SB2 and SB3 groups modulated the composition of dominant taxa by increasing Firmicutes and Acidobacteria abundance. Overall, SB was found to mediate the MAPK signaling pathway, apoptosis, upregulation of tight junction genes, maintenance of the intestinal physical barrier, and regulation of intestinal flora, thereby alleviating glycinin-induced intestinal damage.

A workflow for developing a cost- and time-efficient, single nucleotide polymorphism (SNP)-based assay for species and hybrid identification is described. In a reference set (n = 46), the developed assay identified individuals of two closely related species, the Atlantic salmon (Salmo salar L., n = 23) and brown trout (Salmo trutta, n = 23), with 100% accuracy. Furthermore, species and hybrid identification using field-collected embryos had 98.1% concordance (155/158) to more expensive and time-consuming methods that utilized multiple SNP markers. The method can be integrated into management and conservation plans to quantify species' spawning distribution and hybridization rates.