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The variability of growth variables and age structure in bullhead Cottus gobio was studied in a single river catchment by comparing populations inhabiting river reaches with different thermal regimes. Age and growth variables were determined by examining 540 sagittal otoliths from specimens ranging between 19 and 146 mm total length. Growth of young bullhead (0+ and 1+ years) was higher in the warmest sites, especially in relation to water temperature during the growing season (spring and summer). Growth of older bullhead (2+ to 5+ years) was negatively related to mean water temperature of the site. The growth performance of bullhead over its whole life cycle was negatively correlated with water temperature, which could be partly explained by a higher energy allocation to reproduction in the warmest sites. Life span was longer in the colder sites (7 years) than in the warmer ones (4 or 5 years), and bullhead matured earlier in the warmer sites (age 1+ or 2+ years) compared to the colder ones (age 2+ or 3+ years). These results, combined with previous data on reproductive traits, suggest the possible effects that global warming could have on bullhead population dynamics. 相似文献
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The dilution effect describes the negative association between host biodiversity and the risk of infectious disease. Tests designed to understand the relative roles of host species richness, host species identity, and rates of exposure within experimental host communities would help resolve ongoing contention regarding the importance and generality of dilution effects. We exposed fathead minnows to infective larvae of the trematode, Ornithodiplostomum ptychocheilus in minnow‐only containers and in mixed containers that held 1–3 other species of fish. Parasite infection was estimated as the number of encysted worms (i.e., brainworms) present in minnows following exposure. The results of exposure trials showed that nonminnow fish species were incompatible with O. ptychocheilus larvae. There was no reduction in mean brainworm counts in minnows in mixed containers with brook sticklebacks or longnose dace. In contrast, brainworm counts in minnows declined by 51% and 27% in mesocosms and aquaria, respectively, when they co‐occurred with emerald shiners. Dilution within minnow + shiner containers may arise from shiner‐induced alterations in minnow or parasite behaviors that reduced encounter rates between minnows and parasite larvae. Alternatively, shiners may act as parasite sinks for parasite larvae. These results highlight the role of host species identity in the dilution effect. Our results also emphasize the complex and idiosyncratic effects of host community composition on rates of parasite infection within contemporary host communities that contain combinations of introduced and native species. 相似文献
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Rainbow trout have been introduced to six of the seven continents and currently are widely stocked for sport fishing. Despite their broad distribution, outside of New Zealand, little is known about the effects of rainbow trout on native species, especially fishes. We conducted experiments in an artificial stream to assess hypotheses that stocked rainbow trout significantly affected: (1) mesohabitat use, (2) foraging success, (3) social behavior, and (4) spatial organization of warpaint shiners (Luxilus coccogenis) a common native minnow found in southern Appalachian streams, with similar patterns of microhabitat use to rainbow trout. We replicated experiments at high and low natural densities (two and five warpaint shiners) and spring/fall (12 °C) and summer (17 °C) temperatures. Treatments included: (1) a control (five warpaint shiners), (2) trout (five warpaint shiners and one rainbow trout), (3) large fish control (five warpaint shiners and one river chub) and (4) density control (six warpaint shiners). The presence of rainbow trout produced a shift by warpaint shiners from pool mesohabitats to shallower, higher velocity habitats with more variable substrata, as well as reduced prey capture success, feeding efficiency, and distance from the front of the tank (i.e., warpaint shiners moved closer to food release points), and increased the distance to the additional fish (i.e., avoidance of the rainbow trout). Negative effects on foraging behaviors were stronger in 12 °C treatments. In a realistic stream flume the presence of rainbow trout produced effects that likely influenced individual fitness of warpaint shiners. The potential effects of stocking rainbow trout on native non-game fishes, such as warpaint shiners should be assessed when implementing or evaluating stocking programs. 相似文献
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Fish in the Kanawha River were collected with a 0. 5-m plankton net in main-channel borders and in open areas of backwaters and with a 1-m2 enclosed dropbox in shallow backwater habitats. Larval emerald shiners, Notropis atherinoides , were twice as dense, and gizzard shad, Dorosoma cepedianum , 2. 5 times as dense in main-channel borders as in backwaters; larval Lepomis spp. were 20 times as dense in backwaters as in main-channel borders. Smaller Lepomis larvae used open-water backwater areas primarily; larger larvae migrated to vegetated backwater habitats later in the summer. Backwaters appear crucial for the maintenance of nest-building fish species in temperate rivers, just as floodplains are necessary for the maintenance of high species diversity in tropical rivers. 相似文献
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I. D. S. I. P. Thilakaratne J. D. McLaughlin D. J. Marcogliese †‡ 《Journal of fish biology》2007,71(2):519-538
Seven biomarkers in 204 spottail shiners Notropis hudsonius were examined for effects of pollution and parasites on fish health at localities along the St Lawrence River, Canada. The number of pigmented macrophage centres and pigmented macrophages in the spleen was significantly higher at polluted localities receiving urban and industrial effluents than at reference localities, indicating that they were good indicators of exposure to pollution in spottail shiners. Seven of the nine species of parasites found in 1+ year fish showed significant correlations with biomarkers. More parasites (18 species) but fewer correlations with biomarkers were observed in 2+ year fish, indicating that parasite effects were more pronounced in young spottail shiners. A significant negative relationship was observed between condition factor and Neoechinorhynchus rutili in 1+ year fish, suggesting its potential pathological significance in young spottail shiners. High abundance of Plagioporus sinitsini was associated with higher spleen macrophage counts and lower indices of condition at polluted localities. Furthermore, infection by P. sinitsini in polluted conditions appeared to have a greater negative effect on fish health than either stressor alone, providing further evidence that parasites should be considered when examining effects of pollution on fish health. 相似文献
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Population dynamics of brown trout (Salmo trutta) in a breton stream (France): The non-migrant spawners.The biological factors of the population dynamic of brown trout in a tributary of the Scorff river, have been studied during 4 years. The characteristics of the spawners, present in the stream before the spawning migration from the main river, are described. These spawners were born in the stream and stayed there during their entire life-span. Among mature fish the sex ratio was always in favour of males. During the third and the fourth years of life, annual mortality rate was 70% for males and 50% for females. 1+ spawners were these which had the best 0+ growth rate. A majority of males first matured at 1+ years of age. On an average, 1+ females were responsible for 25% of the total reproductive potential. The number of 3+ and 4+ females seemed to depend on the fishing effort. 相似文献
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The life-history characteristics of the river blenny Salaria fluviatilis in a Mediterranean stream in north-east Spain have been studied. The maximum age observed was 4+ years in both sexes, although only age groups 0+ and 1+ years were well represented. For both sexes, growth was rapid between April and June (before the summer drought) and in October. The instantaneous rate of monthly growth (April to October) was positively correlated with water depth. All fish attained sexual maturity during their first year of life. Females spawned multiple times. Spawning occurred mainly from June to August, although older females (2+ years old) began in May. The relationship between fecundity and total length recorded for older females in the spring was not significantly different from that obtained for 1 year-old females in the summer. The mean diameter of ripe oocytes, however, was greater in older females. Larger eggs that were laid during a period of good food supply (spring) might have a higher probability of survival. The results suggest that female fecundity is affected by environmental conditions. The species is characterized by fast growth, early maturity, multiple spawning and limited longevity. This may be a good life-history strategy for small fish species in unstable environments, where adult mortality is high, variable or unpredictable. Some life-history traits of the river blenny suggest that this species might be vulnerable to more severe drought conditions than those associated with the Mediterranean climate. 相似文献
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为了获得印度北部赣达(Ganga)盆地河流中野生卡特拉(鱾)种群的年龄结构和重要生长参数,对该鱼的年龄和生长进行了研究.鳞片取自商业捕捞和实验室饲养的样品.根据研究分析,该鱼最大年龄可达8龄;巴吉拉蒂河(Bhagirathi R.)的种群平均体长为521.51 mm,退算体长为288.9-1132.3 mm;旁遮普邦(Punjab)Satluj河种群平均体长为641.6 mm,退算体长为335.4-1096.08 mm.2龄时,种群线性生长率(Cl)和体重增加率(Cw)表现出迅速下降的趋势.其它生长参数值(Clt)也呈现快速下降.退算体长差异(ANOVA)分析显示,生活在赣达盆地不同流域中的种群,1 -4 龄组的长度差异较明显(P<0.05),高龄组(5 -8 )差异不显著.根据本项研究结果,提出了对印度北部赣达盆地相关河流中生活的野生卡特拉(鱾)种群资源持续利用的对策. 相似文献
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Synopsis Instantaneous feeding, assimilation, and growth rates for white sucker larvae and young common shiners and guppies (1–2 mg initial dry weight) were measured. Food consisted of natural zooplankton. Linear relationships were obtained between growth and feeding rates for instantaneous feeding rates up to 0.5 mg-1 day-1. Maximum gross conversion efficiencies (K1) were 0.26, 0.31, and 0.24 for suckers, shiners, and guppies respectively. Particle-size-conversion efficiency (-log K1 per log predator-prey size ratio) was 0.15 for suckers, 0.14 for shiners, and 0.18 for guppies. These values are lower than most available estimates of particle-size-conversion efficiency for carnivorous zooplankton and piscivorous fish, indicating that young planktivorous fish are among the most efficient predators at transferring biomass up the biomass size spectrum in aquatic ecosystems. 相似文献
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The growth history of anadromous white-spotted charr in northern Japan: a comparison between river and sea life 总被引:1,自引:0,他引:1
K. Morita 《Journal of fish biology》2001,59(6):1556-1565
Anadromous white-spotted charr Salvelinus leucomaenis in a natural river in northern Japan migrated to the sea mainly at age 3+ years. Sea-run charr grew faster than parr, particularly as first time migrants. Sea-run charr repeated seaward migration up to three times; the observed maximum age was 5+ years old. The likelihood ratio test identified significant differences in asymptotic size and individual growth variability between parr and sea-run charr. Sea-run charr had an asymptotic size ( L ∞ ) twice as large as parr, while the growth parameter ( K ) was similar between sea-run and parr. Growth variability was higher for parr than for sea-run charr. 相似文献
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Growth, density and production of juvenile Atlantic salmon and brown trout were studied in three different sections of the Kvassheimsåna River in south-western Norway from 1979 to 1983. Section 1. in the upper part of the river, is located above a waterfall impassable for migratory salmonids and is surrounded by grazing land. Sections 2 and 3, in the middle and lower parts of the river, are influenced by agricultural activity. Total nitrogen concentration varied between 250 and 1000 μg l ?1 in section 1 and 1500 and 2500 μg l?1 in sections 2 and 3. Total phosphorus (Tot-P) concentrations also increased with decreasing altitude: 19–46 μg l?1 in section I and 31–101 μg l ?1 in sections 2 and 3. The number of 0 + salmon in sections 2 and 3 varied between 30.1 and 167.8 specimens 100 m ?2, with means 90.2 and 95.2 specimens 100 m ?2:, respectively; the density of 1 + salmon, with mean values of 16.3 and 51.0 specimens 100m?2 was significantly correlated with the original fry density. The growth rate of 0+ salmon was not inversely related to cohort density, but was significantly so for 1 + salmon. Mean annual salmon production in section 2 was 1595 g 100 m?2 year 1, and in section 3 was 841 g 100m?2 year 1. A logarithmic function gave the best curve fit between salmon production and mean annual biomass. Thus, production levelled off for the highest values recorded in section 2, and perhaps approached the carrying capacity of the stream. A multiple regression analysis showed that yearly variation in 1 + salmon density was the single factor accounting for most of the total variability in production (60%). Variation in water temperature and nutrient content were not significantly related to variation in fish production. Densities of brown trout were low in all sections (<20 specimens 100m ?2). Fry density was highest in section 3 and parr density in section 1. All age groups of sympatric brown trout grew significantly faster in sections 2 and 3 compared with allopatric brown trout in section 1. 相似文献
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The dispersion of salmon and trout of 0 +, 1 + and 2 + age classes was examined by electrofishing 12 sections of a stream in Perthshire, Scotland at the end of the growing season in September to October in 1972 and 1976. In 1972 sections ranged in surface area from 21 to 122 m2 and had volumes of 5.0–17.3 m3 and when surveyed in 1976 surface areas were 15–106 m2 and volumes 2.1–6.7 m3 . In 1976 widths and areas of sections were 63–87% of the values for 1972, depths were 39–68% and volumes 28–52% of the earlier values. These differences were due to 1976 being drier and warmer. In both years, all sections contained 0 + and 1 + age classes of salmon and trout and some sections contained 2 + age salmon and trout. The total density of fish in a section ranged from 1.9 to 3.9 m−2 in 1972 and from 3.72 to 6.08 m−2 in 1976. There was an inverse relationship, significant in 1972 only, between the density of 0 + salmon and that of 1 + trout in the different sections. Densities of both 0 + and 1 + salmon in the sections were inversely correlated, and those of 0 + and 1 + trout were directly correlated, with area of water deeper than 10 cm. 相似文献
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A field experiment during autumn, winter and spring was performed in a small stream on the west coast of Sweden, aiming to examine the direct and indirect consequences of density-dependent intercohort competition in brown trout Salmo trutta . Individual growth rate, recapture rate and site fidelity were used as response variables in the young-of-the-year (YOY) age class, experiencing two different treatments: presence or absence of yearlings and over-yearlings (age ≥ 1+ year individuals). YOY individuals in stream sections with reduced density of age ≥ 1+ year individuals grew significantly faster than individuals experiencing natural cohort structure. In the latter, growth rate was negatively correlated with density and biomass of age ≥ 1+ year individuals, which may induce indirect effects on year-class strength through, for example, reduced fecundity and survival. Movement of YOY individuals and turnover rate ( i.e. proportion of untagged individuals) were used to demonstrate potential effects of intercohort competition on site fidelity. While YOY movement was remarkably restricted (83% recaptured within 50 m from the release points), turnover rate was higher in sections with reduced density of age ≥1+ year individuals, suggesting that reduced density of age ≥1+ year individuals may have released favourable microhabitats. 相似文献
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Effects of angling exploitation on brown trout populations were assessed by comparing fished sections with close ones unfished for at least 20 years, in mountain streams of Asturias (Northern Spain). Both the fish size and age structure significantly differed among sections in the expected direction according to their exploitation status. The main effects were a significant decrease in age structure complexity (diversity), life span, and percent individuals above the legal limit size in the exploited stocks versus the unexploited ones. Trout above the minimum length limit for fishing (18 cm) averaged 19.47% of the fish caught in the unfished sections (sd = 4.01; n = 5), and 4.72% (sd = 3.46; n = 4) in those subjected to angling. Furthermore, fish older than 4 years represented 39.84% (sd = 8.53) and 1.19% (sd = 1.60) of the catch, respectively. Effects on recruitment (density of young fishes) and growth rates (length at age 1 + to 3 +) were not absolutely consistent, though maximum values were associated with fished sections. 相似文献
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David M. Walters Mike J. Blum Brenda Rashleigh Byron J. Freeman Brady A. Porter Noel M. Burkhead 《Biological invasions》2008,10(8):1229-1242
Human disturbance increases the invasibility of lotic ecosystems and the likelihood of hybridization between invasive and
native species. We investigated whether disturbance contributed to the invasion of red shiner (Cyprinella lutrensis) and their hybridization with native blacktail shiner (C. venusta stigmatura) in the Upper Coosa River System (UCRS). Historical records indicated that red shiners and hybrids rapidly dispersed in the
UCRS via large, mainstem rivers since the mid to late 1990s. We measured the occurrence and abundance of parental species
and hybrids near tributary-mainstem confluences and characterized populations at these incipient contact zones by examining
variation across morphological traits and molecular markers. Red shiners represented only 1.2% of total catch in tributaries
yet introgression was widespread with hybrids accounting for 34% of total catch. Occurrence of red shiners and hybrids was
highly correlated with occurrence of blacktail shiners, indicating that streams with native populations are preferentially
colonized early in the invasion and that hybridization is a key process in the establishment of red shiners and their genome
in new habitats. Tributary invasion was driven by post-F1 hybrids with proportionately greater genomic contributions from
blacktail shiner. Occurrence of red shiners and hybrids and the relative abundance of hybrids significantly increased with
measures of human disturbance including turbidity, catchment agricultural land use, and low dissolved oxygen concentration.
Red shiners are a significant threat to Southeast Cyprinella diversity, given that 41% of these species hybridize with red shiner, that five southeastern drainages are invaded, and that
these drainages are increasingly disturbed by urbanization. 相似文献
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Summary Sagittal otoliths were used for age determination in 1121 specimens of Micromesistius australis, caught in waters of the South-West Atlantic during the cruises made by the ships Walther Herwig and Shinkai Maru in agreement with the Argentine Republic, during the years 1978 and 1978/1979, respectively. The interpretation of growth rings required the otoliths to undergo a paraffin wax embedding and cutting technique. The relations otolith length-fish length and fish length-half otolith width were linear. Thus, back calculations, when necessary, were made by a simple extrapolation. Numbers of males and females were nearly equal, resulting in a sex ratio of 1:1.09. Length frequencies and age distributions were calculated for each sex separately. A significant difference in growth between sexes was found, curves for each were derived. A linear, regression was made and the Von Bertalanffy equation estimated as: Lt=56.90 [1-e-0.1983 (t+1.84)], in males, and Lt=60.08 [1-e-0.1769 (t+2.07)] in females, with Lt in cm and t in years. For estimation of these equation parameters age groups 2–16 years in males and 2–22 years in females were taken into account. All theoretical Lt values and almost all observed lengths for females were greater than those of males in corresponding age groups. Previously published observations about M. australis on this subject, are not in agreement or only in partial accord with present results. These are discussed. Original photographs of otolith cross sections illustrating age determination methods are presented for the first time in age and growth studies of this species. 相似文献
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Jo V. Arnekleiv Jan G. Davidsen Timothy F. Sheehan Sarah J. Lehnert Ian R. Bradbury Lars Rønning Aslak D. Sjursen Gaute Kjærstad Barbara A. Lubinski Kjell J. Nilssen 《Journal of fish biology》2019,94(1):154-164
A survey of the Kapisillit River system was conducted in 2005 and 2012 to study the only indigenous Atlantic salmon Salmo salar population in Greenland. Little is known about its characteristics or its relationship with other S. salar populations across the species range. Juvenile S. salar were captured in all stations surveyed within the lower river with the highest densities lower in the river and decreasing densities with increasing distance from the river mouth. Captured juveniles ranged from 0+ to 7+ years old and the predominant smolt age was between 4 and 6 years. Median length of 0+ and 1+ juveniles in August–September was 38.8 and 70.4 mm, respectively. The proportion of mature male parr increased from 4% for 1+ year old fish to 95% for fish greater than 2 years old. Genetic analysis using 96 single nucleotide polymorphisms (SNP) revealed a high degree of genetic similarity between collections, extremely low genetic diversity and low estimates of effective population size (Ne = 28.7; 95% CI = 19.7–42.4). Genetic comparison to range-wide S. salar populations demonstrated that the Kapisillit River S. salar is an outgroup of the eastern Atlantic stock complex, which is consistent with the hypothesised colonisation from the east. River morphology and the absence of glacier runoff are hypothesised to be the main reasons for the relatively high river temperatures supporting this self-sustaining population of S. salar. Given its uniqueness and persistence, this population represents an important part of range-wide biodiversity of S. salar. 相似文献