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An 8-week feeding trial investigated the optimum dietary vitamin K3 requirements of largemouth bass. A total of 600 healthy fish (12.96 ± 0.07 g) were fed diets containing varying levels of vitamin K3 at 0.78 (K0), 5.80 (K5), 10.82 (K10), 15.84 (K15), and 20.85 (K20) mg/kg with four replicates per level. Results showed that dietary vitamin K3 enhanced growth, with weight gain rate and specific growth rate in K15 trials significantly higher than K0 trials (P 0.05). However, the supplementation of vitamin K3 significantly contributed to calcium accumulation in muscle tissues and vertebrae (P 0.05). The antioxidant capacity was improved with the addition of vitamin K3, which was inconsistent with the changes in malondialdehyde and MK-4 (a form of menaquinone) within liver and serum, suggesting that the toxicity of excessive artificial vitamin K3 may account for this difference. Using regression analysis, the appropriate dietary vitamin K3 levels within a largemouth bass diet was determined to be in the range of 9.93–15.22 mg/kg, which will provide a reference for the preparation of vitamin premix and artificial diet for largemouth bass.

This study investigated the effects of replacing fishmeal with Clostridium autoethanogenum protein (CAP) on growth, feed utilization and intestinal histology of largemouth bass (Micropterus salmoides). The control diet contained 350 g/kg fishmeal, and then dietary fishmeal was decreased to 300 g/kg, 250 g/kg, 200 g/kg, 150 g/kg and 100 g/kg by CAP inclusion, respectively (FM-30, FM-25, FM-20, FM-15, FM-10). The largemouth bass (110.0 ± 1.0 g) were fed one of the six diets for 8 weeks. The groups of FM-30, FM-25 and FM-20 showed the similar weight gain (WG) and feed conversion ratio (FCR) to the control (P > 0.05), while the WG of FM-10 group was decreased by 15.9%, and FCR increased by 0.12 when compared to the control (P 0.05). In conclusion, CAP could replace 150 g/kg fishmeal in diet (350 g/kg fishmeal) without adverse effects on growth, feed utilization and intestinal histology of largemouth bass.

The present study was conducted to estimate the optimum requirement of phosphorus in practical diets for largemouth bass (Micropterus salmoides). Six iso-energetic and iso-nitrogenous diets were formulated with the supplementation of monocalcium phosphate (MCP) of 0, 5, 10, 15, 20 and 25 g/kg in basal diet containing 350 g/kg fish meal, respectively. The digestible phosphorus of the six diets was measured as 5.7, 6.7, 7.8, 8.7, 9.3 and 10.0 g/kg, respectively. Each diet was randomly fed to triplicate groups of 25 juvenile fish (initial body weight, 16.0 ± 0.2 g) for 60 days. The results showed that weight gain increased, and feed conversion ratio decreased with the increase of dietary phosphorus. When dietary MCP exceeded 15 g/kg (digestible phosphorus of 8.7 g/kg), the WG and FCR were maintained at the similar values. The crude ash, phosphorus and calcium contents in whole body, apparent digestibility of phosphorus and protein retention also increased with the increasing phosphorus level in diets. Vertebrae phosphorus and calcium levels and plasma phosphorus showed no further increase when dietary MCP reached 20, 20 and 10 g/kg with digestible phosphorus of 9.3, 9.3 and 7.8 g/kg, respectively. Broken-line analysis indicated that the digestible phosphorus requirement for largemouth bass were 8.9, 8.7 and 9.6 g/kg based on weight gain, feed conversion ratio and vertebral phosphorus content. In conclusion, the supplementation of MCP in a diet containing 350 g/kg fish meal improved the growth and feed utilization of largemouth bass, and the digestible phosphorus requirement was suggested to be 8.7–8.9 g/kg with MCP supplementation of 15.0–15.8 g/kg.

La Trobe University Faculty of Science, Technology and Engineering Murray Darling Freshwater Research CentreMDFRC item.Coastal lagoons of the principal islands of Bass Strait, between Australia's mainland and Tasmania, were sampled in two summers. Many, particularly those of low to moderate salinity, contain relatively rich assemblages of microinvertebrates and some endemic Australian freshwater algae. Several species of testate amoebae and rotifers could not be referred to known morphotypes and are probably new species. The presence of certain species on islands of Bass Strait provides a link between populations in mainland Australia and others in Tasmania. Those lagoons are identified that, by virtue of catchments or buffer zones clothed in native vegetation, are favourable for the survival of a native and partly endemic microbiota.

This study assessed the effects of feed carbohydrate content on intestinal physical barrier and immunity in juvenile largemouth bass (Micropterus salmoides). Triplicate groups of juvenile fish (4.1 ± 0.2 g) were fed low (LCD, 7%), medium (MCD, 12%) and high (HCD, 17%) carbohydrate diets for eight weeks. Gut histology revealed the slight infiltration of inflammatory cells and moderate loss of mucous membrane layer in HCD group. Expression of ZO1, occluding, and claudin7 genes and epidermal growth factor receptor (EGFR) gene were significantly decreased in HCD group indicating the impairment of tight junction and epithelial cell regeneration. The results showed the significant (P 0.05) reduction of antioxidant capacity in HCD group compared to LCD. Furthermore, expression of intestinal ERS-related genes such as IRE1, Eif2α, GRP78, CHOPα and CHOPβ in HCD group was significantly higher than the LCD group. In addition, HCD induced the up-regulated expression of inflammatory (IL-8, IL-1β, TNFα and COX2) and apoptosis (TRAF2, bax, casepase3, caspase8 and casepase9) related genes in fish intestine. The data generated in this study clearly demonstrated that HCD induced ERS and oxidative stress, which promoted intestinal inflammation and apoptosis in juvenile largemouth bass.

In this paper, a method for the enzymatic modification of pectin, in which gallic acid (GA) and propyl gallate (PG) were grafted onto pectin molecules in an aqueous/organic two-phase system catalyzed by lipase, was proposed. The potential reaction mechanism was explored through UV–Vis, FTIR and 1H NMR spectroscopic methods and density functional theory. Results suggested that the lipase played a dual role during the modification by catalyzing the hydrolysis of methyl ester bonds of pectin in the aqueous phase and the esterification between the 4-OH of GA and PG and the –COOH of pectin in the organic phase. Moreover, the effects of GA and PG on the antioxidant and the antibacterial activities of pectin were evaluated, and results showed that the antioxidant and the antibacterial activities of modified pectin were better than those of native pectin. The effect of modified pectin on the quality of fresh bass (Lateolabrax maculatus) was further studied. Results suggested that, compared to control group, the total viable count, histamine level, malondialdehyde content and acid value of bass fillets treated with modified pectin were significantly reduced, whereas the sensory score was significantly increased.

Estimating metabolic rate in wild, free-swimming fish is inherently challenging. Here, we explored using surgically implanted heart rate biologgers to estimate metabolic rate in two warmwater piscivores, bowfin Amia calva (Linneaus 1766) and largemouth bass Micropterus salmoides (Lacepede 1802). Fish were surgically implanted with heart rate loggers, allowed to recover for 24 h, exposed to a netting and air exposure challenge, and then placed into respirometry chambers so that oxygen consumption rate (ṀO2 ) could be measured in parallel to heart rate (fH ) for a minimum of 20 h (ca. 20 estimates of ṀO2 ). Heart rate across the duration of the experiment (at 19°C) was significantly higher in largemouth bass (mean ± s.d., 45 ± 14 beats min-1 , range 18-86) than in bowfin (27 ± 9 bpm, range 16-98). Standard metabolic rate was also higher in largemouth bass (1.06 ± 0.19 mg O2 kg-1 min-1 , range 0.46-1.36) than in bowfin (0.89 ± 0.17 mg O2 kg-1 min-1 , range 0.61-1.28). There were weak relationships between fH and ṀO2 , with heart rate predicting 28% of the variation in oxygen consumption in bowfin and 23% in largemouth bass. The shape of the relationship differed somewhat between the two species, which is perhaps unsurprising given their profound differences in physiology and life history, illustrating the need to carry out species-specific validations. Both species showed some potential for a role of fH in efforts to estimate field metabolic rates, although further validation experiments with a wider range of conditions (e.g., digestive states, swimming activity) would likely help improve the strength of the ṀO2 -fH relationship for use in field applications.

Japanese dace (Pseudaspius hakonensis) foraging and predator avoidance behaviors were studied in dace schools with and without vicinity predators in Lake Nojiri, Nagano Japan. Dace and invasive smallmouth bass (Micropterus dolomieu), which were the only predator observed, were found interacting in shallow habitat along the shoreline. Dace exhibited remarkably different total foraging, foraging modes, and predator avoidance behavior when smallmouth bass were in vicinity. Total foraging was significantly reduced, foraging mode shifted from predominantly benthic foraging to water column foraging, and dace schooled tighter indicated by a significant decrease in nearest neighbor distance and increase in neighbor alignment. These findings show that in Lake Nojiri, dace recognize smallmouth bass as a predator and utilize predator avoidance behaviors. However, the severely decreased total dace foraging when smallmouth bass are in vicinity indicates that even when direct predation is avoided, the indirect effects of reduced foraging and heightened vigilance likely negatively impact dace growth and survival.

Yellowfin sea bream (Acanthopagrus latus) is an important economic fish, which is seriously threatened by various fish viruses. In this study, a cell line designated as ALL derived from the liver of yellowfin sea bream was developed and characterized. The cell line grew well in Dulbecco's modified Eagle's medium containing 10%-20% foetal bovine serum at 28°C. Amplification of the cytochrome B gene indicated that ALL cells originated from yellowfin sea bream. The modal chromosome number of ALL cells was 48. ALL cells were efficiently transfected with pEGFP-N3 plasmids, indicating the potential application of ALL cells in exogenous gene manipulation studies. ALL cells were susceptive to three main fish viruses, including viral haemorrhagic septicaemia virus (VHSV), red-spotted grouper nervous necrosis virus (RGNNV) and largemouth bass virus (LMBV). The replication of VHSV, RGNNV and LMBV in ALL cells was confirmed by quantitative real-time polymerase chain reaction, virus titre and transmission electron microscopy assays. Moreover, ALL cells could respond to VHSV, RGNNV and LMBV infections, as indicated by the differential expression of antiviral genes involving in the innate immune response. In conclusion, the newly established ALL cell line will be an excellent in vitro platform for the study of the virus-yellowfin sea bream interaction.

We describe observations of sea lamprey (Petromyzon marinus) and striped bass (Morone saxatilis) incursions into Labrador, Canada. While P. marinus have been periodically observed in similar latitudes, their numbers have conspicuously increased in estuarine environments in 2020. In contrast, M. saxatilis were not observed from Labrador until 2017 but appear to be declining after the initial surge in abundance that peaked in 2018. It remains unclear whether spawning populations of either species exist. Given the potential to negatively affect species of commercial and cultural importance through predation, follow-up surveys are warranted.

We conducted acute toxicity studies using semi-static protocols to examine the lethal responses of Australian bass and silver perch exposed to antimony (Sb) oxidation states in Sb(III) (10.5-30.5 mg L-1) and Sb(V) (95.9-258.7 mg L-1). Bioavailability and the effects of Sb on body ion regulation (Na, Ca, Mg, and K) were also investigated. Antimony species-specific effects were observed with exposure to both Sb oxidation states. Median lethal concentrations (LC50s) for Sb(III) were 13.6 and 18 mg L-1 for Australian bass and silver perch, respectively, and the LC50 for Sb(V) in Australian bass was 165.3 mg L-1. The LC50 could not be calculated for silver perch exposed to Sb(V) as the maximum exposure concentrations produced 40% mortality but a larger-than value of > 258.7 mg L-1 was estimated. Relative median potency values derived from the LC50s were 0.1 Sb(III) and 12.2 and 16.6 Sb(V) for Australian bass and silver perch, respectively, demonstrating greater toxicity of Sb(III) to both fish species. Antimony uptake in fish was observed. Median critical body residue (CBR50) values of 77.7 and 26.6 mg kg-1 for Sb(III) were estimated for Australian bass and silver perch, respectively, and 628.1 mg kg-1 for Sb(V) in Australian bass. Bioconcentration factors (BCFs) for both Sb(III) and Sb(V) did not change with exposure but the greater BCFs for fish exposed to Sb(III) indicate that it is more bioavailable than Sb(V) in acute exposure. No effects on whole-body Na, Ca, Mg, or K ions were observed with fish exposure to either Sb species.

The study aimed to investigate the effects of dietary sodium butyrate (NaBT) supplementation on the gut health of largemouth bass (Micropterus salmoides) fed with a high soybean meal diet. Three isonitrogenous and isolipidic diets were formulated: a high fishmeal group (Control); a high soybean meal group (SBM), in which the 30% fishmeal protein in the Control diet was replaced by soy protein; and an NaBT group, in which 0.2% NaBT was added to the SBM diet. Each diet was fed to triplicate tanks (20 fish in each tank). After 8 weeks of feeding trial, the distal intestine and intestinal digesta of the fish in each treatment were sampled. The results showed that fishmeal replacement and NaBT supplementation did not affect fish growth performance. Dietary 0.2% NaBT supplementation improved intestinal morphology, increasing the villus width and villus height and reducing the width of lamina propria. The distal intestine of fish in the control and NaBT groups demonstrated lower activities of total superoxide dismutase (T-SOD) and glutathione peroxidase (GPx) and a lower malondialdehyde (MDA) content, compared with the fish in the SBM group. Moreover, the addition of 0.2% NaBT in the feed significantly decreased the expression of tumor necrosis factor α (TNF-α) and interleukin 1β (IL-1β) compared to the SBM diet. PCoA and UPGMA analyses based on weighted UniFrac distances demonstrated that intestinal microbial communities in the NaBT group were closer to those in the control group than to those in the SBM group. In addition, dietary 0.2% NaBT supplementation significantly increased the abundance of Firmicutes and Bacteroidetes and decreased the abundance of Tenericutes at the phylum level. Furthermore, the abundance of Bacteroides, Lachnospiraceae_unclassified, and Lachnospiraceae_uncultured was significantly increased, while that of Mycoplasma was significantly decreased in fish intestine at NaBT group at the genus level. In conclusion, dietary NaBT supplementation had beneficial roles in protecting the gut health of largemouth bass from the impairments caused by soybean meal.

Predator-prey interactions exert significant influence over the survival of juvenile fish cohorts. Therefore, susceptibility of a habitat to invasion is influenced by the capacity of native predators to regulate invasive species through consumption. Closely related predators often share similar characteristics (e.g., odors or body morphometry), and prey species capable of expressing generalized behavioral responses to predators with similar characteristics may increase their chances for survival. Here, we examined how naive juvenile silver carp (Hypophthalmichthys molitrix), an invasive Asian carp, respond to three predator odors from predators commonly found in Midwestern lakes and rivers of the USA. We tested two congeneric species of bass (largemouth Micropterus salmoides and smallmouth M. dolomieu bass) and one outgroup, longnose gar (Lepisosteus osseus). Additionally, we tested how silver carp conditioned to recognize the odor of one group, largemouth bass, responded to the predator odors of the congeneric species and the outgroup. We found that juvenile silver carp showed no innate response to any of the three predator odors. Additionally, although they could be conditioned to recognize predator odors from largemouth bass, they were unable to generalize predator odors to smallmouth bass or longnose gar odor. These results suggest that invasive species could be less likely to persist in environments with diverse predator communities than environments of equal densities with uniform predator communities and that future studies should continue to explore this area as well as focus on understanding dynamics in predator-prey interactions of invasive species.

O_LIThe larval stage in fish development is characterized as a critical period with unusually high mortality rates. Additional stress may be imposed on fish larvae as fresh waters brown in color due to increased inputs of dissolved organic matter from the terrestrial watershed. Both energy transfer and foraging efficacy are predicted to decrease as light availability declines with browning.nC_LIO_LIHere, we investigated the balance between indirect versus direct effects of browning on zooplankton-larval fish interactions. Experimental tanks were established in the laboratory where water color was altered with increasing concentrations of SuperHume (water color measured as absorbance at 440 nm = 1.6 - 10.8 m-1). Phytoplankton and zooplankton densities were monitored across treatments for one month to assess possible changes in community structure leading up to fish spawning (i.e., late Spring in central Virginia, USA). We then introduced larval largemouth bass to the tanks to assess indirect effects on larval fish feeding rate and growth. Additionally, direct effects on the foraging efficiency and selectivity of largemouth bass and bluegill were determined with separate short-term feeding experiments using the same experimental setup.nC_LIO_LIBrowning did not directly alter the ability of larval fish to see and capture prey across our brown water treatments. However, significant indirect effects on larval fish foraging, growth, and survival were observed as phytoplankton and zooplankton densities decreased with increasing water color.nC_LIO_LIOur data suggest lake browning will reduce energy transfer to larval fish, during a critical stage of development, due to a reduction in prey availability but not visual foraging.nC_LI

Fragmentation of river systems by dams can have substantial genetic impacts on fish populations. However, genetic structure can exist naturally at small scales through processes other than isolation by physical barriers. We sampled individuals from five native fish species with varying life histories above and below a dam in the lower Boardman River, Michigan, USA, and used RADseq to investigate processes influencing genetic structure in this system. Species assessed were white sucker Catostomus commersonii, yellow perch Perca flavescens, walleye Sander vitreus, smallmouth bass Micropterus dolomieu, and rock bass Ambloplites rupestris. We detected significant differentiation within each species, but patterns of population structure varied substantially. Interestingly, genetic structure did not appear to be solely the result of fragmentation by the dam. While genetic structure in yellow perch and walleye generally coincided with “above dam” and “below dam” sampling locations, samples from our other three species did not. Specifically, samples from rock bass, smallmouth bass, and, to a much lesser extent, white sucker, aligned with a putative Great Lakes (GL) group that contained mostly individuals sampled below the dam and a putative Boardman River (BR) group that contained individuals sampled both above and below the dam, with some evidence of admixture among groups. We hypothesize that the GL and BR groups formed prior to dam construction and our samples largely represent a mixed stock that was sampled sympatrically outside of the spawning season. Support for this hypothesis is especially strong in smallmouth bass, where GL fish were 151 mm smaller than BR fish on average, suggesting a potential ontogenetic habitat shift of young GL fish into the lower river for feeding and/or refuge. Our study illuminates the complex dynamics shaping genetic structure in fragmented river systems and indicates that conclusions drawn for a single species cannot be generalized.

An in situ bioassay approach was used to determine whether aquatic contaminant stressors in a large Atlantic river ecosystem affect the survival three fish species; the largemouth bass (Micropterus salmoides, juveniles), the fathead minnow (Pimephales promelas, adults), and the robust redhorse (Moxostoma robustum, juveniles). Hatchery-propagated fish were placed into cages to assess site-specific survival in the Yadkin-Pee Dee River of North Carolina and South Carolina, USA. Contaminants were measured in the caged fish and sediment and surface water at each site. No apparent longitudinal trends in fish survival were detected, and contaminant concentrations varied among sites. Juvenile largemouth bass and robust redhorse did not survive past 13 and 23 days with corresponding Kaplan-Meier median survival estimates of 9.7 d and 12.1 d, respectively. Survival of adult fathead minnows deployed in cages alongside the juvenile fish averaged 43% survival at the end of the 28-d exposure with a 22-d median survival estimate. The intersex condition, an indicator of endocrine disruption, was not observed in any adult fathead minnow. Contaminant accumulation in surviving fathead minnows was apparent, with highest accumulated concentrations of polychlorinated biphenyls (34.6-93.4 ng/g dry weight), organochlorine pesticides (19.9-66.1 ng/g dry weight), and mercury (0.17-0.63 μg/g dry weight). Contaminants and other water quality stressors in this river system appear to detrimentally impact juvenile fish survival with presumed effects at the fish assemblage and community levels. This article is protected by copyright. All rights reserved.

Predator–prey systems face intensifying pressure from human exploitation and a warming climate with implications for where and how natural resource management can successfully intervene. We hypothesized young salmon migrating to the Pacific Ocean face a seasonally intensifying predator gauntlet when warming water temperature intensifies a multiple predator effect (MPE) from Striped Bass Morone saxatilis and Largemouth Bass Micropterus salmoides. We evaluated this hypothesis using data synthesis and simulation modeling.Contemporary studies based on acoustically tagged fish reaffirmed older observations that Chinook Salmon smolts must transit the Delta before water temperature reaches 20°C or mortality will be nearly 100%. Striped Bass attack rates on tethered smolts were insensitive to distance from shore and water temperature, whereas Largemouth Bass attack rates were highest near shorelines in warm water, supporting the temporal aspect of the hypothesis. Whether the combined effects of the two predators produce an MPE remains unconfirmed due to limitations on quantifying salmon behavior.We used multiple simulation models to try to reconstruct the empirical relationship between smolt survival and water temperature. Simulations reinforced attack rate results, but could not recreate the temperature dependence in smolt survival except at higher than observed temperatures. We propose three hypotheses for why and recommend discerning among them should be a focus of research.We found significant linear relationships between monthly mean inflow to the Delta from each of its two largest tributaries and monthly mean water temperatures along associated salmon migration routes, but these relationships can be nonlinear, with most of the correlation occurring at low inflows when water temperature is largely controlled by air temperature and day length. As the global climate warms, changed circumstances in predator–prey relationships may present important challenges when managing species vulnerable to extinction in addition to presently more abundant species., We build upon previous conceptual models of how intersecting impacts of multiple predators can render former habitats unsuitable to migratory animals and test the conceptual model with a case study. The case study focuses on the potential impacts of two non‐native predators on Chinook Salmon smolts as the young salmon migrate through California's Sacramento‐San Joaquin Delta on their way to the Pacific Ocean.

Largemouth bass (LMB; Micropterus salmoides) recruitment is limited by a critical developmental period during early life stages, but this mechanism may be less important within non-native habitats. We conducted boat electrofishing surveys in four tidal lakes of California’s Sacramento–San Joaquin Delta (SSJD) from 2010 to 2011 to describe introduced LMB recruitment dynamics. We evaluated growth, proximate composition, and health indices of young-of-the-year (YOY) LMB among tidal lakes and developed an integrated count model to determine how factors known to affect LMB recruitment shape SSJD population structure. Our results show a mismatch among growth, nutrition, and YOY abundance, where the tidal lake with the most abundant and fastest-growing LMB had the poorest nutritional status. The warm winter water temperatures and lack of a hatching-cohort growth advantage suggests overwinter starvation plays a less important role in SSJD LMB recruitment than in many native LMB habitats. Collectively, our results suggest that habitat characteristics (submerged aquatic vegetation) and not overwinter mortality shapes SSJD LMB population structure, a mechanism consistent with contemporary hypotheses about the altered fish community structure of the SSJD.

Striped Bass naturally inhabit a wide range of temperatures, yet little is known about the processes that control their acute and chronic temperature limits. The objective of this study was to determine the effect of temperature acclimation on acute thermal maxima and physiology of juvenile Striped Bass. Juvenile fish were acclimated to 15, 25 or 30 °C for 4 weeks, then split into two sampling groups: post-acclimation and post-critical thermal maximum trials. We found that fish survived in all acclimation temperatures with little change to underlying hematology, and that critical thermal maximum (CTmax) increased with increasing acclimation temperature. At CTmax, fish acclimated to 30 °C had elevated plasma cortisol, lactate and potassium levels. These results suggest that, while 30 °C is likely to be outside their thermal optima, Striped Bass can survive at high temperatures. This ability to cope with warm temperatures may provide an advantage with increasing global temperatures.

Purpose. Largemouth bass (Micropterus salmoides), a fish species native to freshwaters of North America, is a promising object of aquaculture all over the world. This is evidenced by the fact that this species is currently actively cultivated in aquaculture of more than 50 countries worldwide, on all continents, with the exception of Antarctica and Australia, both for recreational fishing and as a table fish. If we consider the history of breeding and cultivation of the largemouth bass, we can note a tendency to a continuous expansion of the stages of cultivation and transition from polyculture to monoculture. For example, in the first half of the last century, fish farms in the United States raised mainly juveniles of largemouth bass for stocking to natural water bodies, but currently most farms use the full production cycle from fry to marketable fish. In addition, earlier largemouth bass was used in many countries mainly as an additional object of aquaculture (biomeliorator) to increase the production of common carp, but now, thanks to the development of recreational fishing, it is increasingly becoming the main object of aquaculture, which is facilitated by the intensification of cultivation methods. Nowadays, there are many methods of growing largemouth bass, from the simplest, extensive, when fish are raised on natural food supply, to most intensive using flow-through aquaculture systems and off-season spawning. On the territory of Ukraine, it may be effective to use pond aquaculture of largemouth bass, which begins from the production of larvae and fry at fish farms. This stage of fish farming will be discussed in this article. Findings. This article contains brief information on method of natural spawning of largemouth bass, filling ponds with water, selection of broodstock and norms for their stocking to spawning ponds, spawning behavior of fish, peculiarities of caring for larvae and fry, sorting juveniles, as well as minimizing injuries during manipulations with fish. Practical value. Information from this review can be used for development of a new method for production of largemouth bass larvae and fry at warm-water pond farms in Ukraine, taking into account climatic conditions and local specificities of aquaculture. Key words: Largemouth bass, Micropterus salmoides, recreation fishing, sport fishing, pond fish farm, aquaculture, biomeliorator, larvae, fry, polyculture, monoculture, intensification, perspective species.

Habitat use and diet composition of invasive smallmouth bass, Micropterus dolomieu, Japanese dace, Pseudaspius hakonensis, and pale chub, Opsariichthys platypus, were studied for two years in the Middle Chikuma River, Nagano, Japan. Habitat use of dace and chub overlapped both years but showed differences from smallmouth bass. Additionally, smallmouth bass habitat use differed greatly between years, as young smallmouth bass were found in uncharacteristically fast flowing habitat in 2018 and predominantly in more typical slow flowing habitat in 2019. This use of fast flowing habitat in 2018 appears to be influenced by the high overall fish density, especially for smallmouth bass. Diet composition, studied in 2018, overlapped significantly between the three species in riffle habitat and overlap became less significant in run and pool habitat where smallmouth bass fed increasingly on fish prey. We therefore suggest that the interactions between smallmouth bass and dace and chub shift from predominantly predation in slow flowing habitat to resource competition in faster flowing habitat.

Availability of shelter is an important component of habitat selection for animals as it can influence survival (protection against harsh physical conditions and predation) and growth (energy acquisition and expenditure). Few studies address the effect of shelter on metabolic expenditures associated with non-mechanical tasks (excluding station holding or movement). The main goal of this study was to investigate the influence of shelter use on metabolic traits of smallmouth bass (Micropterus dolomieu) from two populations (Kiamika River and Lake Long). Respirometry experiments on smallmouth bass were conducted to measure standard metabolic rate (SMR), resting metabolic rate (RMR), aerobic scope (AS), recovery time (RT) and excess post-exercise oxygen consumption (EPOC) in the presence or absence of shelter. The presence of shelter did not affect most metabolic traits, except for RMR, which was reduced in the presence of shelter for Lake Long fish. The results of this study also show that larger fish had lower SMR in the presence of shelter than when it was absent. When accounting for social hierarchy, there were no differences in most metabolic traits in dominant or subordinate fish in the presence or absence of shelter, except for RT, which was significantly lower in the presence of shelter for dominant fish. These results do not support the existence of an unequivocal relationship between individual metabolic traits and the presence of shelter. If physiological motives may influence the use of shelter, sheltering in itself might not have important consequences on energy expenditures required for non-mechanical tasks.

Azomite is a hydrated calcium sodium aluminosilicat rich in rare earth elements. To investigate the dietary effects of Azomite on growth, intestine microbiota and morphology, immunohematological changes and disease resistance, seven diets with Azomite supplementation of 0 (the control), 1.0, 2.0, 3.0, 4.0, 5.0 and 6.0 g/kg (A0, A1, A2, A3, A4, A5, A6), were prepared and fed to largemouth bass, Micropterus salmoides (7.96 ± 0.19) for 60 days. The results revealed that the weight gain (WG) increased first and then decreased with the increasing dietary Azomite, and the A2 group presented the highest WG and lowest feed conversion ratio among all the groups. The supplementation of 2.0 g/kg Azomite significantly increased the intestine protease activity, the crude protein of whole body and protein retention (P0.05), and high inclusion of Azomite (6.0 g/kg) significantly reduced the lipid retention (P0.05). The amounts of red blood cells in A5, A6 groups, white blood cells in A3, A5, A6 groups and lymphocyte in A2-A6 groups were all significantly higher than those in the control group (P0.05). In addition, serum superoxide dismutase and catalase activities in A5, A6 groups, and serum alkaline phosphatase and lysozyme activities in A2-A4 groups showed significantly higher values than the control group (P0.05). Intestinal microbiota analysis indicated that the Tenericutes abundance was increased, whereas Proteobacteria abundance was decreased in all Azomite supplemented groups. The villus height in A2-A4 groups, and the villus width in A2 group were significantly higher than those of the control group (P0.05). The cumulative mortality was reduced by the addition of 2.0-5.0 g/kg Azomite after challenging with A. hydrophila (P0.05). In conclusion, proper addition of Azomite in diets improved the growth, intestine morphology, immune response and disease resistance in largemouth bass, and the optimal inclusion was estimated to be 2.0-3.0 g/kg diet.

HighlightsLight design is needed in recirculating aquaculture systems.A long photoperiod is beneficial to largemouth bass growth.Low light intensity is beneficial to largemouth bass growth.Abstract. In this study, recirculating aquaculture systems (RAS) were used to culture juvenile largemouth bass, and the effects of LED light intensity and photoperiod on the survival and growth performance of juvenile largemouth bass were studied. In the light intensity experiment, largemouth bass juveniles with an initial weight of 0.53 ±0.02 g were subjected to a two-month feeding experiment under two different light intensities: group A, at 0.5 W m-2 in the first month and 5 W m-2 in the second month; and group B, at 5 W m-2 in the first month and 0.5 W m-2 in the second month. The results showed that in the first month of the experiment, the growth rate of fry was faster in group A than in group B. After changing the light intensity, the weight of the fry in group B after one month of growth had exceeded and was significantly higher than that in group A. Based on the above experimental results, we conducted a photoperiod experiment. Largemouth bass juveniles with an initial weight of 0.56 ±0.02 g were cultured for two months under four different photoperiods (24L:0D, 16L:8D, 8L:16D, and 0L:24D). The light intensity of the four groups was 0.5 W m-2. The fry growth rate was fastest in the 24L:0D photoperiod group and slowest in the 0L:24D photoperiod group. The growth rate of the 24L:0D photoperiod group was significantly higher than that of the 0L:24D photoperiod group (p < 0.05). The final fry weight was highest in the 24L:0D group, followed by that in the 16L:8D group and 8L:16D group, with the lowest weight observed in the 0L:24D group (p < 0.05). Although the different light conditions in the two experiments had no significant effect on the survival rate of juvenile largemouth bass (p > 0.05), a low-intensity light environment with a continuous photoperiod during the juvenile largemouth bass culture process promoted growth and development. Keywords: Growth, Largemouth bass, Light intensity, Photoperiod, RAS.

Restoration practices aimed at fish habitat enhancement often include installation of instream structures. However, mixed outcomes have been reported regarding structure effectiveness, while mechanisms underlying success remain unclear. The interactions between fish and flow conditions generated by instream structures and their subsequent impact on fish energetics may provide some insight. This study seeks to quantify how restoration structures, simulated by cylinders in three orientations, alter the energetics and swimming stability of smallmouth bass (Micropterus dolomieu). Accelerometers measured swimming stability while a respirometer measured energy expenditure at multiple velocities. Particle image velocimetry was used to characterize flow fields behind structures. Structures generated flow conditions that benefited fish energetically. Fish had a smoother gait and expended less energy when swimming near a structure, regardless of its orientation. Benefits varied with flow conditions; reductions in energy expenditure were especially apparent at high flow velocities. Results suggest that restoration structures may be most energetically beneficial in stream systems with consistently high velocities and inform restoration by indicating flow conditions in which structures provide the greatest energetic benefits for fish.

Fishmeal has long been a staple protein feedstuff for fish, but its global shortage and high price have prompted its replacement with alternative sustainable sources. In this experiment involving largemouth bass (a carnivorous fish), a new mixture of feedstuffs (45% poultry byproduct meal, 30% soybean meal, 15% blood meal, and 10% krill shrimp meal) was added to low (14.5%) fishmeal diets along with 0.0%, 0.5% taurine, 0.5% methionine, or 0.5% taurine plus 0.5% methionine (dry matter basis). The positive control diet [65.3% fishmeal (46% crude protein on dry matter basis)] and all low-fishmeal diets contained 40% true protein and 10% lipids. There were 3 tanks per treatment group (20 fish/tank). Fish with the mean initial body weight of 16.6 g were fed to satiety twice daily. Compared with the unsupplemented low-fishmeal group, supplementing either 0.5% methionine or 0.5% methionine plus 0.5% taurine to the low-fishmeal diet improved (P

The feeding method is of great significance for aquaculture production and cost. In recent years, research on intelligent feeding, a method based on fish appetite, has been trending. Few studies, however, have focused on fish welfare issues that can result from intelligent feeding. In this study, an adaptive feeder based on a practical intelligent feeding method was designed to evaluate whether this intelligent feeding method would impair fish welfare compared to traditional automatic feeding. The results indicated that the amount of residual feed and size inhomogeneity in the traditional group was significantly higher than that in the intelligent group. The results of the growth indicator showed that the weight gain rate (WGR) in the intelligent feeding group was significantly higher (30.17%) than in the traditional feeding group. Although no significant differences were observed in the survival rate (SR), the condition factor (CF) and the hepatosomatic index (HSI), the specific growth rate (SGR) in the intelligent feeding group was significantly increased by 8.33% while the feed conversion rate (FCR) was reduced by a remarkable 17.07% compared to the traditional feeding group. Moreover, intelligent feeding significantly improved the pepsin activity of the bass. In terms of immunity and antioxidant capacity, however, the fish in the intelligent feeding group had a significantly lower lysozyme (LZM) level than those fed with the traditional method. For superoxide dismutase (SOD), the intelligent group also displayed a lower activity value, although it was not significant. The intelligent feeding group had 0.14 nmol/mg protein higher malondialdehyde (MDA) activity than the traditional group. Regarding stress, although no statistical significance was observed, the cortisol level in the intelligent group was 1.9 ng/ml higher than in the traditional group. Together, these data suggested that the intelligent feeding method can significantly improve fish growth but may also result in stress and suppress innate immunity.

Carbon nanomaterials are emerging contaminants released into the environment primarily through anthropogenic processes, where they primarily partition into soils and sediments. Aquatic animals that inhabit, forage, or choose prey in the benthic zone are vulnerable to dietary exposure to sediment-associated carbon nanomaterials. Since carbon nanomaterials are hydrophobic, dietary exposure may alter the availability, metabolism, storage, and transport of lipids in the intestinal lumen or at the epithelial barrier, affecting downstream biological processes. To assess the effect of single-walled carbon nanotubes (SWCNTs) on the gastrointestinal lipidome of aquatic species, a feeding experiment with adult largemouth bass (Micropterus salmoides) was conducted. After 8 weeks of exposure to SWCNTs via the diet, the intestinal abundance of ceramides and several classes of lyso- and phospholipids were significantly altered. Additionally, functional profiling with Metaboanalyst revealed changes in pathways related to fatty acid biosynthesis in exposed fish. These results suggest that though SWCNTs do not pass through the gastrointestinal epithelium, they may alter gut homeostasis through interactions with intestinal lipids.

Molecular markers were used as indicators in assessing the genetic diversity of a fish, they allow for direct observation of genetic information and estimation of genetic relationships between the population and species. In the present study, eleven SCoT primers and ten ISSR primers were used to estimate the genetic diversity among the four mullet species namely Mugil cephalus, Liza ramada, Liza grana, and Valamugil seheli collected from four different Egypt governorates Alexandria, Ismailia, Port Said and Damietta. The two markers SCoT and ISSR successfully amplified amplicons with a total number of 176 and 132 of which 153 and 111 were polymorphic, representing a percentage of polymorphism of 86.9% and 84.1% polymorphic amplicons/ primer, respectively. The similarity indices ranged from 0.47 to 0.84, 054 to 0.92 and 0.52 to 0.86 for SCoT, ISSR and combined, respectively. Cluster analysis based on similarity matrices of SCoT, ISSR and combined dendrograms revealed some similarities; for example, the grouping of the Mugile cephallus (Alexandria, Ismailia and Port Said) together and the grouping Valamugil seheli (Ismailia and Damietta) based on the three dendrograms. Also, Liza ramada, Liza garana (Damietta) and Mugile cephallus ( Damietta) were clustered together based on the three dendrograms. From gene sequencing and NCBI Blast analysis identified of gene location in fish genomes. The NCBI blast tool was used to align our gene with the NCBI database and it revealed that this sequence is highly similar to a sequence located on fish species called Dicentrarchus labrax (the European bass). Also, the sequence is located on Chr1 near a gene called “Type II keratin E3”.

Submitted 2020-06-30 | Accepted 2020-09-01 | Available 2020-12-01 https://doi.org/10.15414/afz.2020.23.mi-fpap.79-87 The present study assessed the effects of two initial stocking densities (low – LD, 4.23 kg m-3, moderate – MD, 8.05 kg m-3) on growth, health and fillet quality of largemouth bass (Micropterus salmoides), and on yield of lettuce (Lactuca sativa) and radicchio (Cichorium intybus group Rubifolium) produced in a low-tech recirculating aquaponic system. A total of 104 largemouth bass (initial body weight: 236 ± 38 g) were randomly stocked in eight 500 L tanks (four per stocking density) and monitored during a 70-day period. Vegetables yield was similar in LD and MD groups. Lettuce yield (6.33 kg m-2) was in line with typical values, whereas radicchio showed a negligible yield (1.34 kg m-2). Likewise, fish final weight (263 g, on average), specific growth rate (0.17% d-1), feed conversion ratio (2.72), and mortality (4.8%) did not differ between treatments. Fish morphometric indices, slaughter results and fillet quality were not affected by stocking density. In conclusion, the production of lettuce was successful in the tested system, whereas the production of radicchio did not achieve satisfactory results. Growth performances of the largemouth bass were poor and further investigations are required to optimize the rearing of this fish species in low-tech aquaponic systems. Keywords: largemouth bass, lettuce, radicchio, water quality, flesh quality References BAsMANN, B. et al. (2017). Stress and welfare of African catfish (Clarias gariepinus Burchell, 1822) in a coupled aquaponic system. Water, 9(7), 504. https://doi.org/10.3390/w9070504 BROWN, T. G. et al. (2009). Biological synopsis of largemouth bass (Micropterus salmoides). Canadian Manuscript Report of Fisheries and Aquatic Sciences, 2884, v + 27 p. CHAVES-POZO, E. et al. (2019). 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Five isonitrogenous and isocaloric diets [containing 54, 30, 15, 10, and 5% fishmeal crude-protein (CP), dry matter (DM) basis] were prepared by replacing fishmeal with poultry by-product meal plus soybean meal to feed juvenile largemouth bass (LMB, with an initial mean body weight of 4.9 g) for 8 weeks. All diets contained 54% CP and 13% lipids. There were four tanks of fish per treatment group (15 fish/tank). The fish were fed twice daily with the same feed intake (g/fish) in all the dietary groups. Results indicated that the inclusion of 15% fishmeal protein in the diet is sufficient for LMB growth. However, some of the fish that were fed diets containing ≤ 15% fishmeal CP had black skin syndrome (characterized by skin darkening and retinal degeneration, as well as intestinal and liver atrophies and structural abnormalities). The concentrations of taurine, methionine, threonine and histidine in serum were reduced (P

Nocardia seriolae is the causative agent of nocardiosis in both marine and freshwater fish. Here, we report on multiple outbreaks of nocardiosis associated with elevated mortality (23-35%) in farmed largemouth bass in Sichuan, China, from 2017 to 2018. A total of 9 strains isolated from diseased largemouth bass were identified as N. seriolae by phenotypic characterization, 16S rRNA and hsp65 gene sequence analysis. The clinical signs of infected largemouth bass included hemorrhage, skin ulcers and prominent tubercles varying in size in the gill, liver, spleen and kidney. Experimental infection indicated that these isolates were the pathogens responsible for the mortalities. In vitro antibacterial activities of 12 antibiotics against N. seriolae isolates were determined as minimum inhibitory concentrations. Histopathological observation of diseased fish infected with N. seriolae showed necrotizing granulomatous hepatitis, nephritis, splenitis, epithelial hypertrophy and hyperplasia with degenerative changes of the epithelium in the gill. Large quantities of bacterial aggregates were found in the necrotic area of the granuloma by Lillie-Twort Gram stain and immunocytochemistry. Our findings indicated that N. seriolae is a serious threat to the largemouth bass Micropterus salmoides industry in Southwest China.

The carnivorous largemouth bass Micropterus salmoides has been introduced to many regions and poses a threat to native aquatic organisms due to predation, resulting in a significant decrease in biodiversity. Under conditions of prey scarcity, the largemouth bass is thought to consume smaller conspecifics. However, little is known about this species’ dietary reliance on intraspecific predation and its impact on the population structure. We investigated the length–frequency distribution of largemouth bass and estimated their reliance on intraspecific predation using stable carbon and nitrogen isotopes in an agricultural pond with no available prey fish. Almost all individual largemouth bass were collected via the pond drainage system. Within the largemouth bass population, the dominant length class was composed of fish measuring 100–160 mm standard length (SL), whereas few individuals measuring < 100 mm SL (first-year juveniles) were collected. The results from a Stable Isotope Analysis in R mixing model indicated that all four length classes (105–146, 165–180, 216–246, and 300–337 mm SL) of largemouth bass fed mainly on juvenile conspecifics and on red swamp crayfish (Procambarus clarkii). First-year juveniles could have been predated by other individuals of various sizes. The dominant 100–160 mm SL length class may have experienced a weak predation pressure when they were in the first-year juvenile class. Consequently, the largemouth bass population was unbalanced, with few first-year juveniles (< 100 mm SL) and dominance of a 100–160 mm SL length class.

Juvenile striped bass (age-1) of distinct genetic ancestry were re-discovered in the Saint John River, New Brunswick in 2014 after a 35 yr hiatus of recognition. These juveniles were determined to be highly genetically divergent from all possible source populations, hypothesized to be of Saint John River ancestry, and thus considered evidence of the continued existence of the native stock. Successful recruitment of strong year classes of striped bass within the Saint John River, however, appears to be infrequent. We acoustically tagged and tracked juvenile and sub-adult striped bass (n = 37; age 2-4) in the Saint John River in both 2015 and 2016, and identified summer feeding and overwintering habitats that established an in-river residency. Following decades of poor or no recruitment of the native striped bass stock, it is now imperative that managers quickly include monitoring of juvenile and sub-adult striped bass and protection of their habitats in the conservation and recovery efforts for Saint John River striped bass.

ConspectusSilica-alumina catalysts, including zeolites and amorphous silica-aluminas (ASAs), are among the most widely used solid acid catalysts and supports to produce petrochemicals, fine chemicals, and renewable energy. The coordination, distribution, and interactions of aluminum in ASAs have an enormous impact on their acidic properties and catalytic performance. Unsaturated tetracoordinated aluminum (AlIV) species are commonly accepted as the key sites in generating catalytically active Bronsted acid sites (BASs) in silica-alumina catalysts. Extensive efforts focus on increasing the concentration of AlIV as the main route to enhance their Bronsted acidity for efficient catalysis. However, increasing the AlIV concentration either weakens the acid strength in zeolites or lowers Bronsted acidity in ASAs at high Al/Si ratios, impeding acidity enhancement of these popular catalysts."Pentacoordinated aluminum (AlV) species" are potential unsaturated Al species like AlIV but rarely observed in silica-aluminas, and thus, are widely considered unavailable for BAS formation or surface reactions. In this Account, we will describe novel strategies for the controlled synthesis of AlV-enriched ASAs using flame-spray pyrolysis (FSP) techniques and highlight the contribution of AlV species in acidity enhancement, together with their structure-activity relationship in the conversion of biomass-derived compounds into valuable chemicals. Using various in situ and advanced 2D solid-state NMR (SSNMR) experiments, the studies of the acidic properties and local structure of AlV-enriched ASAs reveal that AlV species can highly populate on ASA surfaces, promote BASs formation, and facilitate adaptable tuning of BASs from moderate to zeolitic strength by synergy with neighboring Al sites. Moreover, the BASs with enhanced acidity can work jointly with surface Lewis acid sites or metal active species for bifunctional catalysis on AlV-enriched ASAs. Compared to zeolites, these AlV-enriched ASAs are highly active in acid-catalyzed biomass conversion, including alcohol dehydration and sugar conversion reactions, as well as in promoting the performance of supported metal catalysts in chemoselective hydrogenation of aromatic ketones. These new insights provide a state-of-the-art strategy for strongly enhancing the acidity of these popular silica-alumina catalysts, which offers an interesting potential for a wide range of acid and multifunctional catalysis.

Winter habitat selection by Striped Bass (Morone saxatilis) has been described as opportunistic, but due to the length and severity of winter at its northern range, winter habitats in the north are predicted to be restricted in distribution and carefully selected. Here we describe the locations and environmental conditions supporting winter aggregations of adult Striped Bass including periods under ice cover in the Saint John River, New Brunswick using acoustic telemetry. Striped Bass of both Saint John River (72%) and other ancestry (28%) were observed to overwinter within the river’s four mainstem lakes and embayments to which the individuals returned each fall. Most non-Saint John River ancestry Striped Bass were observed in habitats nearest the river mouth in winter. Striped Bass travelled to winter habitats from fall feeding locations from October to November, and only four tagged individuals departed the river at this time. Temperature, dissolved oxygen, and salinity conditions best described the winter habitats. By demonstrating the non-random distribution of Striped Bass during winter and identifying a gradient of habitat use by Saint John River ancestry Striped Bass in this northern river system, it is apparent that protection of these locations is critical for the long term conservation of Striped Bass populations in Canada.