Aquaculture and Fisheries最新文献

Animals rely on olfaction to detect and process invaluable chemical information about their environment. For olfaction to function, chemicals must first be detected, which leads to the activation of signal-transduction pathways at the peripheral olfactory organ. As the olfactory system is in direct contact with the environment, the system is constantly vulnerable to damage by contaminants entering the atmosphere or hydrosphere. Contaminants may have a variety of effects, including disrupting olfactory signals generated during chemical detection, or altering numerous targets along the signal transduction pathway. With any impairment of chemical detection, animals may be unable to rely on olfaction to make correct decisions about their environment and thus their fitness. While other reviews have focussed on olfactory toxicology in general, here we specifically explore how contaminants may affect the signal-transduction pathways at various points and link those changes to olfactory functionality across vertebrates with a focus on fishes.

Reproduction is one of the most crucial physiological processes for the continuation of the generation of any species. Teleost are one of the most divergent aquatic species. The reproductive neuro-endocrine regulatory studies are limited to only few species. Neuroendocrine regulation is a finely tuned complex mechanistic pathways, involving mainly hypothalamic-pituitary-gonad (HPG) axis. Within the HPG axis, gonadotropin-releasing hormone (GnRH) modulates the synthesis and release of pituitary gonadotropins, which act on the gonads to stimulate steroidogenesis and gametogenesis. Very recently, several novel neuropeptides, associated with reproductive regulation, have been identified. Spexin (SPX), a novel neuropeptide coevolved with the galanin/kisspeptin family, has been identified as a regulator of the species-specific reproductive processes in teleost. Pituitary adenylate cyclase-activating polypeptide (PACAP) is another novel member of the secretin-glucagon peptide family that functions as a hypophysiotropic factor involved in regulating pituitary hormone secretion in fish. These two emerging neuropeptides have pleiotropic functions, but information regarding their exact roles in fish reproduction is very limited. An updated overview of the mechanistic reproductive functions of these two new neuropeptides are highlighted in this review.

Fishing with artificial light has become one of the most advanced, efficient, and common methods for the night-time purse seining in Vietnam. This study evaluated the radiation spectrum, CIE chromaticity coordinates, correlated color temperature (CCT), catch rate, fuel consumption, and CO₂ emissions when using Light emitting diode (LED) lamps (0.196 kW) in comparison with the use of metal halide (MH) lights (1 kW) in the offshore purse seine fishery in Quang Tri province, Vietnam. The fishing efficiency of the purse seine fishing boats using LED lamps has increased 1.58 times in catch rate than MH lights, although the energy consumption of LED lamp is 4 times smaller. Fuel consumption of boats per trip using LED lamps was one third of that using MH lights. The use of LED reduced the radiation spectrum, especially the intense UV radiation which negatively affects the health of fishermen. This study also showed the potential of CO₂ emission reduction up to 1.09 tons of CO₂ per trip per boat from the use of LED lamps in the offshore purse seine fishing boats.

Transport is an essential part of the aquaculture and research of the main freshwater aquaculture crayfish Procambarus clarkii in China. However, transport is often accompanied by a low survival rate. Assessing the physiological state of P. clarkii before and after transport may discover the cause of this high mortality rate. In this study, ice-cold and exposed-to-air transport methods were compared using an array of parameters, including relative expression level of heat shock protein 70 (HSP70), content of serum glucose and cortisol, immune parameters (enzyme and immune-related genes), and white spot syndrome virus (WSSV) concentration were investigated to understand the physiological state of P. clarkii before and after transport, as well as the cause of dying crayfish on days 5 and 7 after transport stress. Histological sections of hepatopancreas, gills, and intestines reflected pathological changes. The survival rate of crayfish with ice-cold transport was significantly higher than that with exposed-to-air transport, and mortality peaked at 3–9 days after transport stress. A prolonged response to oxidative stress and short-term immunosuppression was present after transport, and the trend of the WSSV concentration in the hepatopancreas was similar to the mortality rate of P. clarkii. The contents of serum glucose and cortisol, antioxidant enzymes and immune-related indexes, and the concentration of WSSV in hepatopancreas of dying crayfish were significantly higher than those of vibrant crayfish on the 5th and 7th days after transport. The hepatopancreas, intestines, and gills of dying crayfish had varying degrees of damage, and the hepatopancreas and intestines were severely damaged. The results suggested that the death of P. clarkii after transport stress is caused by oxidative stress, the imbalance of reactive oxygen species regulation, and decreased WSSV resistance, which eventually led to irreversible tissue damage. The increase of WSSV in the body of crayfish might be the direct cause of crayfish death.

A poor environment increases fish's susceptibility to myxosporean infection that can cause the death of larval fish, especially for koi fish (Cyprinus carpio). This study aimed to determine the effect of probiotics, local anti-parasitic drugs (kutuklin), and the chemical compound diflubenzuron treatments on the koi immune response. This study used PCR with specific primer 18S SSU rDNA and DNA sequencing to detect Myxobulus phylogenetic. The treatments were divided into 5 groups: Treatment (A) (healthy koi without treatment), (B) (infected koi without treatment), (C) (infected koi with 0.55 mL/30 L probiotics), (D) (infected koi with 1 μL/g of feed kutuklin), and (E) (infected koi with 0.02 mg/5 L dimilin). Myxospore has observed with Scanning Electron Microscopy (SEM) and 4′,6-diamidino-2-phenylindole (DAPI) fluorescence staining. The histological analysis using semi-quantitative scoring methods, and flow cytometry was conducted to analyse the immune response of Cluster of differentiation 4 (CD4⁺), Cluster of differentiation 8 (CD8⁺), Tumor Necrosis Factor-alpha (TNF-α), Interferon gamma (IFN-γ) cells in the gills. Results show that the histological analysis indicated edema, hyperplasia, lamella fusion, congestion, and hypertrophy lesions in infected koi. Treatment with probiotics shows the lowest damage (30.6%). The immune responses of CD4⁺ and CD8⁺ cells to dimilin treatment were 10.54% and 16.86%, respectively. The largest TNF-α and IFN-γ response were for the kutuklin treatment (29.26%) and probiotics treatment (8.23%).