Effects of angling on feeding by largemouth bass

Angling practice significantly effected the time required for largemouth bass Micropterus salmoides to begin feeding. Mean ± s.e. time until feeding resumed was longest for fish that experienced a simulated tournament (15·6 ± 2·2 h) followed by fish that were caught and released (8·4 ± 2·2 h) and controls (0·3 ± 1·6 h). Effects on feeding related to angling practices were maintained throughout the 48 h observation period. Using multiple logistic regression and bioenergetics simulations, decreased growth in fish subjected to competitive or catch-and-release angling events was predicted. Fish subjected to multiple captures in a pond experiment had greater mass loss than those not captured, supporting model predictions.     

The influence of brood loss on nest abandonment decisions in largemouth bass Micropterus salmoides

Largemouth bass Micropterus salmoides broods were experimentally reduced in size to test whether brood size (BS) and simulated brood depredation affect the decision by a male to continue providing care for its brood or to abandon that brood prematurely before its offspring reach independence. The highest ranked of the generalized linear models predicting brood abandonment was based on the number of offspring remaining in a nest following brood devaluation, indicating that parental male fish reassess the value of a brood following perturbation. Paternal M. salmoides were more likely to abandon their broods if initial BS was small before devaluation, and if there was a greater decrease in BS, indicating a threshold for both the amount of brood loss and remaining BS. Larger, older males were also less likely to abandon their brood than smaller, younger conspecifics. These results have broad implications for determining drivers of parental care trade‐offs and how individuals assess the value of a brood.     

Observations on the ecology of Clinostomum marginatum in largemouth bass (Micropterus salmoides)

Over a fifteen month period, beginning October, 1974, approximately 13 500 centrarchids were examined for evidence of infection with metacercaria of Clinostomum marginatum. Species checked included Lepomis macrochirus, L. gulosus, L. auritus, Pomoxis nigromaculatus and Micropterus salmoides. The study site was Par Pond (South Carolina, U.S.A.), an 1120 ha reservoir receiving thermal effluent from a nuclear production reactor. Except for the largemouth bass, M. salmoides , infection percentages among the five species were less than 1%. Among bass, infection varied seasonally, being highest from January to June. From the spring highs of approximately 25 %, the percentages dropped to lows of < 10% in July and August; there was a jump in September-October to another peak of 30% and then a steady decline through December when infection percentages were again less than 10%. Neither body condition nor length of the bass were related to infection percentage or metacercaria density. Infection percentage could not be related to the influence of thermal effluent. Infection percentages did vary from location to location within the Par Pond system. A significant rank correlation could be established between infection percentage and the amount of littoral zone present in the locality from which the bass were taken. It is suggested that the local 'bay effects' are the result of limited home and foraging ranges of the bass in relation to the amounts of littoral zone present in various locations of the reservoir.     

Population responses of plant-associated invertebrates to foraging by largemouth bass fry (Micropterus salmoides)

The effect of foraging by largemouth bass fry (Micropterus salmoides) upon invertebrates associated with aquatic macrophytes was determined using six 4 m² exclosures in Cochran Lake, Michigan during June 1978. The cladoceranSida crystallina rapidly declined in exclosures with fry, but increased in control exclosures without fry. Chironomids and chydorids showed little change in the exclosures.Invertebrate populations and foraging by fry were also monitored in the lake during 1976 and 1979.Sida declined rapidly in June of both years. In 1979, a decline from 2.2 × 10³ to 0.3 × 10³ individuals per m² and a sharp drop in the proportion of adults between 19 and 22 June coincided with the entry of a large school of fry into the study site on 19 June. Chironomids also declined during June of both years, while chydorids became increasingly abundant in mid-summer and showed no evidence of depletion by the fish.These results suggest that populations of certain prey, which are found locally in high densities in the littoral zone, may be highly susceptible to brief episodes of intense predation by fish fry.     

Utilizing stomach content and faecal DNA analysis techniques to assess the feeding behaviour of largemouth bass Micropterus salmoides and bluegill Lepomis macrochirus

In this study, the feeding behaviour of the non‐native invasive predatory fishes largemouth bass Micropterus salmoides and bluegill Lepomis macrochirus was studied in the Ezura River, a northern tributary of Lake Biwa, Japan. Prey composition was estimated based on visual examination of stomach contents and faecal DNA analysis to determine feeding habits of these predatory fishes. Stomach content analysis showed that native fishes (e.g. ayu Plecoglossus altivelis and gobies Rhinogobius spp.) and shrimps (e.g. Palaemon paucidens) were the major prey items for M. salmoides, while snails, larval Chironomidae and submerged macrophytes were the dominant prey items of L. macrochirus. Micropterus salmoides tended to select larger fish in the case of crucian carp Carassius spp., but smaller fishes in the case of P. altivelis and Rhinogobius spp. Faecal DNA analyses revealed prey compositions similar to those identified in predator stomach contents, and identified additional prey species not detected in stomach content inspection. This study demonstrated that both stomach content inspection and DNA‐based analysis bear several inherent shortcomings and advantages. The former method is straightforward, although identification of species can be inaccurate or impossible, whereas the latter method allows for accurate species identification, but cannot distinguish prey size or stage. Hence, integration of morphology‐based and DNA‐based methods can provide more reliable estimates of foraging habits of predatory fishes.     

The influence of environmental temperature and oxygen concentration on the recovery of largemouth bass from exercise: implications for live–release angling tournaments

The impact of variation in water temperature and dissolved oxygen on recovery of largemouth bass Micropterus salmoides from exercise was examined. For this, largemouth bass were first exercised and recovered for either 1, 2 or 4 h at ambient water temperatures (25° C) in fully oxygenated water. Results showed that exercise forced fish to utilize anaerobic metabolism to meet energy demands, and resulted in reductions in anaerobic energy stores adenosine triphosphate (ATP), Phosphocreatine (PCr) and glycogen. Exercise also resulted in a seven‐fold increase in lactate within white muscle. After 2 h of recovery in oxygenated water at acclimation temperature, physiological recovery from exercise was under way, and by 4 h most variables examined had returned to control levels. Next, largemouth bass were exercised at ambient temperatures and recovered for 2 h in environments with either elevated temperature (32° C), reduced temperature (14 and 20° C), hypoxia or hyperoxia. Both elevated and reduced temperature impaired recovery of tissue lactate and tissue ATP relative to fish recovered in water at acclimation temperature, while hyperoxic water impaired recovery of tissue ATP. Moderately hypoxic waters impaired the recovery of plasma glucose, plasma lactate and tissue PCr relative to fish recovered in fully oxygenated water. Results from this study are discussed in the context of critical oxygen and temperature guidelines for largemouth bass. In addition, several recommendations are made concerning remedial treatments used in livewells (tanks) during angling tournaments when fish are recovering from exercise associated with angling.     

The complete mitochondrial genomes of largemouth bass of the northern subspecies (Micropterus salmoides salmoides) and Florida subspecies (Micropterus salmoides floridanus) and their applications in the identification of largemouth bass species

The largemouth bass belongs to the family Centrarchidae, which includes two subspecies: the northern subspecies, Micropterus salmoides salmoides, and the Florida subspecies, Micropterus salmoides floridanus. In this study, the complete mitochondrial genomes of the two subspecies were sequenced, and their genetic differences were identified. The mitogenomes of M. s. salmoides and M. s. floridanus are 16,486 and 16,479?bp in length, respectively. The two subspecies consisted of 37 genes (13 protein-coding genes, 2 ribosomal RNA, and 22 transfer RNA), which are typical for vertebrate mtDNA. Phylogenetic analysis provided statistical support for the monophyly of the family Centrarchidae. Comparison of the two subspecies' mitogenomes revealed a relatively high number (450) of single nucleotide polymorphisms (SNPs) in protein-coding genes. We characterized SNPs in the partial cytochrome c oxidase subunit 1 gene of different individuals from three cultured populations, one wild northern subspecies population, and one wild Florida subspecies population. Twenty-eight SNPs were fixed with alternative nucleotides in the two subspecies, which could be used for differentiating them. Based on this gene, phylogenetic tree and genetic distance analyses supported that cultured largemouth bass in China belongs to the northern subspecies.     

Experimental trophic ecology of juvenile largemouth bass,Micropterus salmoides,and blue tilapia,Oreochromis aureus

Synopsis The potential for feeding competition between largemouth bass, Micropterus salmoides, and blue tilapia, Oreochromis areus, in Lake Fairfield, Texas was evaluated experimentally. Largemouth bass and blue tilapia were grown in cages alone and in combination with each other. The fish were allowed to feed on the natural food within the lake. Largemouth bass grown in combination with blue tilapia were significantly shorter and weighed less than largemouth bass grown alone. Blue tilapia grown in combination with largemouth bass were statistically significantly longer and heavier than blue tilapia grown alone. Largemouth bass grown alone had diets (volume and number of food items) significantly different than the largemouth bass grown with the blue tilapia. Largemouth bass fed primarily on chironomid larvae and pupae, and odonates, whereas blue tilapia consumed vegetable matter, detritus, and chironomid larvae. Length and weight differences between large-mouth bass grown alone and in combination with blue tilapia, in conjunction with the largemouth bass diet shift, support the theory that these two species compete for food resources.     

The diet of largemouth bass, Micropterus salmoides, in Lake Naivasha, Kenya

Lake Naivasha is a freshwater lake situated in the eastern rift valley of Kenya. Only five species of fish are present, all of which have been introduced. Of these, Oreochromis leucostictus, Tilapia zillii and Micropterus salmoides (largemouth black bass) support an important gillnet fishery with bass also being taken for sport. Until bass reached 260 mm f.l. they depended upon invertebrate food organisms. Thereafter crayfish, fish and frogs became increasingly important the larger the size of the bass. The most important invertebrate prey species was the water boatman, Micronecta scutellaris , followed by chironomid and culicid pupae. Zooplank-ton was consumed but only in large quantity by fish smaller than 80 mm. For bass over 260 mm the crayfish, Procambarus darkii , was the principal food. The largemouth bass in Lake Naivasha are generalized macro-predators, feeding principally on free-living animals of a kind most likely to be found in the littoral zones.     

The effects of temperature change on the hatching success and larval survival of largemouth bass Micropterus salmoides and smallmouth bass Micropterus dolomieu

In this study, the effects of abrupt temperature change on the hatching success and larval survival of eggs, yolk-sac larvae (YSL) and larvae above nest (LAN), for both largemouth bass Micropterus salmoides and smallmouth bass Micropterus dolomieu were quantified. Temperature had a significant effect on hatching success and time to 50% mortality, with large heat shocks causing accelerated mortality. The temperature changes shown to influence survival of all life stages, however, were beyond what is typically experienced in the wild. Micropterus salmoides had greater egg hatching success rates and increased survival rates at YSL and LAN stages, relative to M. dolomieu. Additionally, egg hatching success and survival of LAN varied across nests within the study. These findings suggest that temperature alone may not account for variations in year-class strength and may emphasize the need for protection of the nest-guarding male Micropterus spp. to ensure recruitment.     

Effects of sulphuric acid exposure on the behaviour of largemouth bass,Micropterus salmoides

Synopsis Young-of-the-year largemouth bass,Micropterus salmoides, were exposed to four concentrations of sulphuric acid (pH levels 7.2, 6.1, 4.8, and 3.7) for 30 days, and the frequencies of feeding acts and activity bouts, and time budgets were recorded. Juveniles at pH 6.1 and at pH 4.8 performed the two feeding acts, bites and orientations, more often, and spent more time feeding than bass at pH 7.2. Bass at pH 3.7, however, reduced feeding, and spent a significantly larger portion of their time hovering in the water column. Frequencies of comfort and agonistic acts increased with a decline in pH. Alterations of behavioural repertoires of young-of-the-year largemouth bass were useful indicators of sulphuric acid exposure.     

Righty fish are hooked on the right side of their mouths - observations from an angling experiment with largemouth bass, Micropterus salmoides

The development of muscles and bones in fish is laterally asymmetric (laterality). A "lefty" individual has a "C"-shaped body, with its left-side muscles more developed and the left side of its head facing forward. The body of a "righty" is the mirror-image. This laterality causes asymmetric interactions between individuals of different fish species, in that a righty or lefty fish consumes more lefty or righty fish, respectively. To investigate the coupling mechanisms between body asymmetry and predatory behavior, we conducted angling experiments with largemouth bass (Micropterus salmoides). We used the position of the fishhook set in the mouth to indicate the movement direction of the fish when it took the bait. Righty fish had more hooks set on the right side, whereas lefty fish had more on the left side, indicating that righty fish moved more to the left, and lefty fish moved more to the right, in successful catches. The relationship between the hooked position and movement direction was confirmed by video-image analysis of the angling.     

Hunting behavior of Florida largemouth bass, Micropterus salmoides floridanus, in a channelized river

The distribution and behavior of Florida largemouth bass, Micropterus salmoides floridanus, and their main prey (sunfish, genus Lepomis, and the cichlid Tilapia mariae) were studied in southern Florida to determine how fish behave in the simplified habitats found in channelized rivers. Time budgets were constructed from focal animal observations on 69 bass. Patterns of behavior associated with hunting were performed during a significantly higher proportion of the time when bass were in vegetated habitats. Scan samples of the behavior of 236 observed bass revealed that hunting was more common in areas of high structural complexity. Only 38% of observed bass were solitary, with the majority occurring in groups with either conspecifics or in mixed-species groups with similar sized bluegill sunfish, Lepomis macrochirus. Largemouth bass (n=1014) and sunfish (n=1372) were significantly more abundant in areas with vegetation and were almost entirely absent from the water column in the center of the canal. All species of fish avoided the water column, where currents were swift and no cover was available. The structure of the habitat appears to be important in the way largemouth bass organize their activity patterns. This suggests that habitat availability in channelized rivers significantly influences important behaviors such as hunting, thus potentially altering energy budgets and population dynamics of both predator and prey.     

Failure of low-velocity swimming to enhance recovery from exhaustive exercise in largemouth bass (Micropterus salmoides)

This study was intended to discover whether forcing largemouth bass (Micropterus salmoides) to swim at 0.5 body lengths/second following exercise would expedite recovery relative to fish recovered in static water. Exercise resulted in a suite of physiological disturbances for largemouth bass that included a depletion of anaerobic energy stores, an accumulation of lactate, and increased cardiac output. At 1 h following exercise, exhaustively exercised largemouth bass forced to swim exhibited expedited recovery relative to fish in static water, evidenced by lower concentrations of lactate in white muscle, elevated concentrations of phosphocreatine in white muscle, and reduced concentrations of glucose in plasma. By 4 h postexercise, largemouth bass forced to swim during recovery exhibited signs of physiological disturbance that were absent in fish recovered in static water. These signs of disturbance included a loss of osmotically active particles from plasma, elevated lactate in plasma, reductions of phospocreatine in white muscle, and increased cardiac output. These results are discussed in relation to the body of work with salmonid fishes showing physiological benefits to recovering fish in flowing water.     

Selection of reference genes for quantitative real-time PCR normalisation in largemouth bass Micropterus salmoides fed on alternative diets

The partial cDNA sequences of eight reference genes (actb, tuba1, gapdh58, gapdh59, eef1a1, RNA 18 s, pabpc1, ube2I) were cloned from largemouth bass Micropterus salmoides. The expression levels of these eight genes were compared in the various tissues (eye, spleen, kidney, gill, muscle, brain, liver, heart, gut and gonad) of M. salmoides fed on forage fish. The results showed that the candidate genes exhibited tissue-specific expression to various degrees and the stability ranking order was eef1a1 > tuba1 > RNA 18 s > pabpc1 > ube2I > actb > gapdh58 > gapdh59 among tissue types. Four candidate genes eef1a1, tuba1, RNA 18 s and actb were used to analyse the stability in liver tissues of largemouth bass between the forage-fish group and the formulated-feed group. The candidate genes also showed some changes in expression levels in the livers, while eef1a1 and tuba1 had the most stable expression in livers of fish fed on alternative diets within 10 candidates. So eef1a1 and tuba1 were recommended as optimal reference gene in quantitative real-time PCR analysis to normalise the expression levels of target genes in tissues and lives of the M. salmoides fed on alternative diets. In livers, the expression levels of gck normalised by eef1a1 and tuba1 showed the significant up-regulation in formulated feed group (P < 0.05) than those in forage-fish group. While sex difference has no significant effects on the expression levels of gck in both groups.     

A successful population of largemouth bass, Micropterus salmoides, in a subtropical lake in Mozambique

Sectioned otoliths were used for age and growth determination of the alien Micropterus salmoides from Lake Chicamba, a hydroelectric dam in central Mozambique. Marginal zone analysis showed that annulus formation occurred during winter in August and September. The maximum estimated age was 5 years. Growth was described by the 3 parameter von Bertalanffy model as L_t=465.51 (1 – e^{-1.175(t+0.009)}) mm FL. Juvenile growth rate was 23.1 mm per month during their first 7 months of life. The age at 100% maturity was 0.9 years, and spawning occurred during August and September. The juvenile fish fed sequentially on the most abundant prey items. Spawning occured before any of the indigenous fish species and so, there is little inter-specific competition. Conspecific juveniles formed the most important constituent in the adult M. salmoides diet from October to December when alternative prey was limited. The total annual mortality rate (Z) for the species in Lake Chicamba was 1.27 yr^-1, the mean empirical estimate of natural mortality (M) was 0.73 yr^-1, and fishing mortality (F) was calculated at 0.54 yr^-1. The success of M. salmoides in Lake Chicamba was attributed to limited inter-specific and intra-specific competition for prey as a consequence of the timing of the spawning, cannibalism and high mortality rates.     

重复垂钓对鲫幼鱼易钓性和能量代谢及个性的影响

先捕后放是一种重要的鱼类资源保护策略和渔业管理手段。经历先捕后放的被钓鱼类个体的生理与行为会发生变化。当这些个体再次面对人工垂钓诱饵时,可能会呈现更加谨慎的摄饵或鱼钩回避行为。为考察重复垂钓对鱼类易钓性、能量代谢和个性的影响,本研究以鲤科鱼类鲫(Carassius auratus)幼鱼为实验对象,在(25.3±0.1)℃水温条件下对垂钓组和对照组进行3次的能量代谢(标准代谢率,SMR;最大代谢,MMR)和个性(勇敢性、活跃性)测定。其中,垂钓组需进行垂钓实验,而对照组不进行任何垂钓操作。研究发现：(1)重复垂钓显著降低鲫幼鱼的垂钓率,但明显增加单尾平均垂钓时间和整体死亡率。(2)重复垂钓降低鲫幼鱼的体重、肥满度、SMR、MMR、代谢空间(AS)和相对代谢空间(FAS),但整体上不影响勇敢性和活跃性。(3)在测定Ⅰ中,高易钓性个体的体长和开阔区运动时间比大于低易钓性个体,但前者的肥满度小于后者。然而,在测定Ⅱ和Ⅲ中,高易钓性个体的形态参数、能量代谢、个性(勇敢性和活跃性)与低易钓性个体并无差异。研究表明：重复垂钓明显降低鲫幼鱼的易钓性,并且种内个体易钓性的变化方向不尽相同;重复垂钓对鲫幼...     

Effects of temperature,salinity and body size on routine metabolism of coastal largemouth bass Micropterus salmoides

Routine metabolism (i.e. standard metabolism plus a low level of activity) of coastal largemouth bass Micropterus salmoides from Mobile‐Tensaw Delta, AL, U.S.A. was examined as a function of temperature (15, 20, 25 and 30° C), salinity (0, 4, 8 and 12) and body mass (range 24–886 g) using flow‐through respirometry. Functionally, a cubic relationship best described the effect of salinity on respiration; the magnitude of these effects increased with temperature and body mass. The best model predicted that specific respiration (mg O₂ g^?1 h^?1) at temperatures >20° C was lowest at salinities of 0·0 and 9·7, and elevated at 3·2 and 12·0; salinity had little to no effect at temperatures ≤20° C. Respiration increased exponentially with temperature, but when compared with previously published respiration rates for M. salmoides from northern latitudes, predicted respiration was higher at cool temperatures and lower at high temperatures. The reduced energetic cost near the isosmotic level (i.e. c. 9) may be an adaptive mechanism to tolerate periods of moderate salinity levels and may help explain why M. salmoides do not flee an area in response to increased salinity. Further, these results suggest that salinity has high energetic costs for coastal populations of M. salmoides and may contribute to the observed slow growth and small maximum size within coastal systems relative to inland freshwater populations.