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1.
Abstract – This study reports the differential effect of the pseudophyllidean cestode, Ligula intestinalis , on the growth rates of three fish populations of the roach, Rutilus rutilus , under field conditions. Here, we show that only one host-population is affected by parasite-induced gigantism in the first 2 years of host life. Paradoxically, this increase in fish growth is strongly correlated with the parasitic load in plerocercoid stages, in that only the roach population subjected to the heaviest parasitic pressure shows an enhanced growth of cestode-parasitized individuals. This host gigantism observed in only one locality is associated with parasite-induced fish mortality occurring, on average, one year earlier in this fish population when compared to other populations. We discuss the different reasons for this differential parasite effect on growth enhancement across host-population in natural settings. Whether the growth effects represent an adaptive response by the host or a manipulation by L. intestinalis of the host, remains to be elucidated. 相似文献
2.
Abstract – The morphology of three lake-resident Arctic charr, Salvelinus alpinus , populations was studied at two life-history stages in a common-garden experiment. The fish of the same year class were reared under standard hatchery conditions, and 27 morphometric variables (a truss network) were measured from the sampled individuals. Most of the total variation was explained by the overall body robustness, dimensions of the head and caudal peduncle length. After controlling for a body size, significant heterogeneity in body shape was found among populations at both ages. Independent of age, the populations were morphologically highly distinct, although some integration of characters could be found as the fish reached sexual maturity. Sexual divergence accounted for a large part of the within-population shape variation, the mature males having more robust bodies, larger head dimensions and longer pectoral fins compared with the mature females/immature fish. Although the cultured fish may not be totally representative of their wild counterparts, it is reasonable to expect that the observed morphological differences have a genetic basis, presumably reflecting adaptation to local environmental conditions experienced by the charr in their original habitat. 相似文献
3.
Parasitism, water temperature and life history characteristics of the freshwater fish Gobiomorphus breviceps Stokell (Eleotridae) 总被引：1，自引：0，他引：1
Abstract – Life history traits can vary among populations of the same fish species in response to selective pressures exerted by the local environment. Here we used inter-population comparisons to investigate the effects of parasitism and variability in water temperature on life history traits in a New Zealand freshwater fish, the upland bully. Although age and size at maturity varied among populations, they were not significantly related to either temperature regime or average parasite load. Trade-offs between egg size and clutch size were only apparent in one of the seven populations when populations were analyzed separately but became clear when all data were pooled. However, neither average population clutch size or egg size was related to the population's mean parasite load or the local temperature regime. Although the latter two parameters may influence other life history variables, such as the number of clutches produced per season and the partitioning of eggs among clutches, there was no evidence that they influenced life history strategies of the upland bully populations investigated here. Note 相似文献
4.
Abstract – Although stunting is a common phenomenon in fish populations, the consequences of stunted body size on the reproductive ecology of individuals has received little attention. The present study compares the reproductive ecology of bluegill in established stunted and non-stunted populations. Three ponds (two non-stunted and one stunted) were monitored for spawning activity throughout the summer. Parental male bluegill from both non-stunted populations were older, larger, and had greater mating success (number of eggs or fry within nests) than parental males in the stunted population. Stunted bluegill also experienced a shortened reproductive season owing to the delay in onset of spawning. The present study demonstrates that individual size and population size structure can have a marked influence on the reproductive ecology of bluegill. 相似文献
5.
R. J. Scott 《Ecology of Freshwater Fish》2004,13(1):1-7
Abstract – The idea that sexual selection can lead to rapid evolution of premating isolation among independent populations (speciation) has been controversial, but is rapidly gaining acceptance among many evolutionary biologists as empirical examples accumulate. A survey of male signals and female preferences (mate recognition systems, MRSs) across the contact zone between divergent populations of threespine stickleback ( Gasterosteus aculeatus ) in Conner Creek, WA, revealed a spatial pattern of MRSs that is consistent with speciation via sexual selection. Females from locations that possessed melanic males preferred melanic males whereas females from populations possessing typical mosaic males (red chin, blue iris, and blue-green dorsum) preferred mosaic males. I argue that sensory drive sexual selection, acting through geographically varying spectral properties, is responsible for the observed population differences and premating isolation between the adjacent populations. 相似文献
6.
Reproductive characteristics of female longnose dace in the Coweeta Creek drainage, North Carolina, USA 总被引：1，自引：0，他引：1
Abstract – We examined the reproductive characteristics of 38 female longnose dace ( Rhinichthys cataractae ) from one of the southernmost populations of this species during two sampling periods in 1999 (ES=March 1999, LS=June 1999). Our data indicated that ES fish had not spawned, whereas LS fish had begun spawning. The smallest mature female captured was 56 mm SL (age 1+). Mean potential fecundity differed significantly between ES (mean±1 SD=1832±572 oocytes) and LS (mean±1 SD=775±415 oocytes) specimens. Potential fecundity was positively correlated with both standard length and somatic mass for both ES and LS specimens. Oocyte diameter frequency histograms indicated that ES specimens possessed two modes of oocytes, whereas LS fish contained two or three modes. Female longnose dace appeared to spawn more than once during a reproductive season. Oocyte number varied substantially both among individuals within periods and between periods. The number of Mode II oocytes in ES fish was positively correlated with both length and somatic mass. Female longnose dace appeared potentially capable of spawning 6+ clutches per year. GSI values for longnose dace ranged from a high of 21.4% (LS specimen) to 2.4% (ES specimen). Regression analysis demonstrated that there was no evidence of differential reproductive effort between longnose dace of different size in this population. 相似文献
7.
Abstract – In most species, males have a higher reproductive potential than females, leading to skewed reproductive success, particularly in mating systems where pre‐ or postcopulatory sexual selection reinforces inequality in male mating success. We investigated multiple paternity, reproductive skew and correlates of male reproductive success in a wild population of the Trinidadian guppy (Poecilia reticulata). We used nine microsatellite loci to assess the frequency of multiple paternity, number of sires per brood and reproductive skew. Across broods, the frequency of multiple paternity was high with 94% of broods having multiple sires (range: 1–5), resulting in a reproductive skew of 0.14. Variation in male reproductive success was high (range: 0–14 offspring per male), suggesting that there is considerable opportunity for sexual selection. Next, we examined correlations between male reproductive success and sexual coloration, sperm velocity and gonopodium length. Relative area of orange, black, iridescent and total coloration, and sperm velocity were not correlated with reproductive success. However, gonopodium length explained 14% of the variation in reproductive success, suggesting that gonopodium length is likely a sexually selected trait. We discuss these findings in the light of other studies that genetically dissect joint‐sex parentage and examine correlates of male reproductive success in wild populations. 相似文献
8.
Daisuke Takahashi 《Ecology of Freshwater Fish》2008,17(1):71-77
Abstract – Age at maturity in males of the freshwater goby Tridentiger brevispinis , a species with exclusive paternal care, was investigated in two populations in Lake Biwa, Japan, that differed markedly in nest site abundance. At Ohmi-maiko, where nest sites were scarce, most males matured at age 3, and mean body size of males guarding eggs in nests was larger than that of males sampled randomly (including both guarding and nonguarding males) in the population. Conversely, at Minamihama, where nest sites were abundant, many males matured at age 1, and there was no difference in body size between guarding males and males collected randomly. The slope of regression lines between body size of the guarding male and the number of eggs in his nest was greater in Ohmi-maiko than in Minamihama. These results suggest that the shortage of nest sites enhances reproductive success in larger males, probably through male–male competition for nest sites and female mate choice for larger males. I conclude that in nest spawners, the availability of nest sites should strongly affect life-history traits of males through sexual selection. 相似文献
9.
Saeed Keyvanshokooh Ahmad Ghasemi Mohsen Shahriari-Moghadam Rajab Mohammad Nazari & Mehdi Rahimpour 《Aquaculture Research》2007,38(9):953-956
The Caspian roach (Rutilus rutilus caspicus) is regarded as one of the most important commercial species in the Caspian Sea. Despite the commercial and conservation importance of the species, information on genetic relationships and diversities at the molecular level in Rutilus rutilus caspicus is scarce. Six microsatellite loci were analysed to study the genetic variation in two major populations of Caspian roach in the Iranian waters of the Caspian Sea: the Anzali Wetland and Gorgan Bay. The Fst value between populations was 0.07, suggesting that the genetic differentiation was significant (P<0.01). Both the studied populations deviated from Hardy–Weinberg equilibrium proportions at a number of loci, mostly due to the deficiency of heterozygosities. The genetic distance between populations was 0.29, which indicates that the genetic difference among the studied populations is pronounced. The differences between both populations were not statistically significant (P>0.05), neither for average number of alleles per locus nor for observed heterozygosities. The data generated in this study provide useful information on the genetic variation and differentiation in populations of Caspian roach. 相似文献
10.
Abstract – The relationships between size and age at smolting and juvenile growth rates were examined for 13 populations of white-spotted charr ( Salvelinus leucomaenis ). Mean smolt length (ranging 142–210 mm in fork length) and smolt age (2.4–3.7 years) varied significantly among populations and there was a significant negative relationship between smolt length and age. Mean smolt length was positively correlated with mean specific growth rate from age 0 to 1 year, whereas mean smolt age was negatively correlated with specific growth rate. The present study shows that the freshwater environment conditions operating on juvenile growth are important for moulding the phenotypic characteristics of size and age at smolting. 相似文献
11.
池塘养殖斑节对虾生长、发育与性成熟 总被引：1，自引：0，他引：1
为了解不同养殖条件下斑节对虾的生长、外生殖器发育、性腺发育及性成熟之间的关系,对其养殖进行跟踪调查研究.结果显示:①斑节对虾雌雄外生殖器官发育和头胸甲长呈线性关系;②不同养殖环境条件下,斑节对虾性成熟生物学最小型个体无显著差异.雄性精荚出现的生物学最小型个体为头胸甲长3.1 cm,体长11.1 cm,体质量20.0 g;雄性性成熟个体的头胸甲长3.7 cm,体长13.0 cm,体质量37.0 g.池养雌性斑节对虾的性成熟生物学最小型个体以纳精囊的发育完全(可与雄虾交配)为标志,其最小性成熟个体的头胸甲长4.3 cm、体长15.1 cm、体质量53.0 g,雌性性成熟个体为头胸甲长5.0 cm,体长17.0 cm,体质量75.0 g以上;③池塘养殖斑节对虾性成熟与日龄和养殖环境相关.鱼塭雄虾精荚出现的最早时间为日龄120 d前后,其性成熟日龄约为160 d;池塘养殖雄虾精荚出现的最早时间为日龄150 d前后,其性成熟日龄约为260 d.鱼媪雌虾最早交配发生在日龄165 d前后,性成熟日龄205～236 d,池养雌虾最早交配发生在日龄240～ 280 d,性成熟日龄295～360 d以上. 相似文献
12.
Reproductive ecology of two cyprinid fishes in an oligotrophic lake near the southern limits of their distribution range 总被引：3，自引：0，他引：3
A. S. Tarkan 《Ecology of Freshwater Fish》2006,15(2):131-138
Abstract – The reproductive activities of two dominant fish species, roach Rutilus rutilus and rudd Scardinius erythrophthalmus were investigated from August 2000 to July 2002 in an oligotrophic lake, Lake Sapanca, in the northwest of Turkey. A total of 907 roach and 593 rudd individuals were examined. Macroscopic appearance of ovary, gonadosomatic index and oocyte diameter frequency distribution suggested that the spawning season of roach and rudd were from early April (13 °C) to late May (18 °C) and from early May (17.5 °C) to late June (23.5 °C), respectively. The spawning cycles of both species showed the same tendency in two successive years. The estimated mean total lengths at first maturity ( L T50 ) were 12.26 and 14.98 cm for male and female roach, respectively, and 7.12 and 8.10 cm for male and female rudd, respectively. The sizes at 50% maturity corresponded to 3 years for roach and 1 year for rudd, for both sexes. The ratio of males to females was 1.3:1 and 1.2:1 for roach and rudd, respectively. The average condition factor K was 1.21 for rudd and 1.14 for roach, and it was not affected by sex or reproductive effort. Absolute fecundity varied from 7829 to 95,387 eggs between ages 3 and 9 for roach and from 1807 to 35,629 eggs between ages 1 and 7 for rudd. Comparisons of these results with earlier studies from more northern regions revealed that spawning of both species in this area started earlier, but spawning temperature and the duration of spawning was approximately the same. 相似文献
13.
Myxobolus pseudodispar (Gorbunova) is a common parasite of the muscle of roach, Rutilus rutilus L., whereas its actinosporean development occurs in two oligochaete alternate hosts. This paper reports the complete developmental cycle of this parasite in the oligochaete alternate host Tubifex tubifex and the roach. In laboratory experiments, parasite-free T. tubifex specimens were infected by myxospores of M. pseudodispar collected from roach in Lake Balaton. Parasite-free roach fingerlings were infected with floating triactinospores (TAMs) released from oligochaetes on day 69 after challenge. Young plasmodia and spores in roach were first recorded on day 80 post-exposure (p.e.). Myxospores collected from experimentally infected roach initiated a new development in T. tubifex and the resulting TAMs infected roach. No infection of roach resulted from feeding oligochaetes containing mature triactinospores. 相似文献
14.
Abstract – The size structure of a predator population can cause differences in the relative survival of different prey length classes whereby the biggest prey may reach a safe size because of the size-dependent character of predation. In the present study, the diet of European catfish was investigated to examine if catfish feeding can prevent cyprinids from reaching such a size refuge. In the lake studied, catfish was stocked for biomanipulation purposes to reduce unwanted roach and bream populations. Crayfish and roach were the most important prey items of catfish. If only species composition in the diet was considered, no clear changes were recorded in relation to catfish size. However, the length of roach as prey significantly increased with catfish length. Catfish were significantly larger than the other piscivorous fish in the lake, but took relatively smaller roach in comparison with similar-sized pike or pikeperch. Nevertheless, because of the high mean length of catfish, roach cannot reach a size refuge. For unknown reasons, the expected and intended predation on bream was not observed. Catfish took smaller prey than could be expected from mouth gape data. By extending the relationship between catfish as predator and roach as prey beyond the predator length range currently found in the lake, it could be shown that even catfish of 150 cm length will probably feed upon only 65% of all available bream length classes. Therefore, stocking with catfish cannot prevent a size refuge for the bream. 相似文献
15.
Å. Brabrand 《Ecology of Freshwater Fish》2001,10(2):97-104
Abstract – Perch ( Perca fluviatilis ) can act as a piscivore from larval stage VI (body size 10.3 mm) on newly hatched larval roach ( Rutilus rutilus ), bream ( Abramis brama ) and smaller siblings of its own cohort. Consumption rates at this stage were approx. 0.5 prey/perch*h at 21°C. Larval perch predation was strongly gap-limited, and the maximum size of roach consumed by perch (perch length interval 10.3–62.0 mm) under experimental conditions followed the linear regression, Pprey-max. =0.478*LPred. +1.829 ( r 2 =0.99, P <0.001, n =12). Under experimental conditions, predatory 0+ perch substantially affected the size distributions of 0+ roach prey cohorts, since smaller prey individuals were predated more frequently than larger ones. In both unimodal and bimodal size distributions of prey roach, the distributions changed according to the maximum prey size consumed by the added predatory perch. Unimodal prey distributions were positively skewed when piscivorous perch were added compared with controls without predators. According to the size distributions of lake-living 0+ roach and 0+ perch and the relative size difference between prey and predator, the vulnerability of 0+ roach cohort to 0+ perch predation changed from June to September. Prey vulnerability was extremely sensitive to the relative size difference between predator and prey. Therefore differences in hatching time and growth rates between the two species will strongly influence the potential for predator-prey interactions. Note 相似文献
16.
Wataru Doi Than Than Lwin Masashi Yokota Carlos Augusto Strüssmann Seiichi Watanabe 《Fisheries Science》2007,73(2):331-340
ABSTRACT: Sexual maturity, morphological sexual dimorphism, and reproduction of the goneplacid crab Carcinoplax vestita were investigated in Tokyo Bay, Japan, from November 2002 to October 2003. The puberty molt in males was evidenced by changes in the relative size of the chelipeds and merus of the walking legs, and was estimated to occur at a size range of 13.20–18.85 mm carapace length. Post-pubertal females were identified by the relative size of the abdomen and puberty was estimated to occur at a size range of 12.81–15.46 mm carapace length. Sexual dimorphism in C. vestita was observed in all features that showed secondary sexual characteristics. Monthly changes of gonad index in males, and of seminal receptacle index and occurrence of sperm plugs in females were synchronized, and indicated that mating was intense in spring. Ovaries began developing in March. Ovigerous females were found in all months except December, but were clearly more abundant between August and October. Fecundity ranged from 7800 to 57 000 mature oocytes per female per batch and was highly correlated with body size. The results suggest that some females may spawn more than one batch per year. 相似文献
17.
Two genetically distinct populations of chinook salmon, Oncorhynchus tshawytscha (Walbaum), were simultaneously sampled at the confluence of the Yukon and Tanana rivers in 2003. Upper Yukon-Canadian fish had significantly higher infection prevalence as well as more severe infections (higher parasite density in heart tissue) than the lower Yukon-Tanana River fish. Both populations had migrated the same distance from the mouth of the Yukon River at the time of sampling but had significantly different distances remaining to swim before reaching their respective spawning grounds. Multiple working hypotheses are proposed to explain the differences between the two stocks: (1) the two genetically distinct populations have different inherent resistance to infection, (2) genetically influenced differences in feeding behaviour resulted in temporal and/or spatial differences in exposure, (3) physiological differences resulting from different degrees of sexual maturity influenced the course of disease, and (4) the most severely infected Tanana River fish either died en route or fatigued and were unable to complete their migration to the Tanana River, thus leaving a population of apparently healthier fish. 相似文献
18.
S. Vincenzi A. J. Crivellì D. Jesensek J.-F. Rubin G. A. De Leo 《Ecology of Freshwater Fish》2007,16(2):116-123
Abstract – The role of endogenous and exogenous factors in regulating population dynamics of freshwater salmonids is still a matter of debate. The aim of the present work was to assess the relative importance of density-dependent and -independent factors in determining the survival of marble trout ( Salmo marmoratus ) yearlings in two populations living in Slovenian streams (Zakojska and Gorska). The investigation was performed by combining a classical life table analysis with Monte Carlo simulation. Size-dependent fecundity was estimated by stripping wild adults in the fish farm. A significant positive relationship was found between length of marble trout females and the number of eggs produced. Egg density was the major determinant of survival from eggs to age 1+ ( σ 0 ) in both streams. Residuals of the relationship between σ 0 and egg density were positively correlated with rainfall only in Zakojska, probably because, within a certain range, more intense rainfalls increases stream flow and, consequently, suitable habitat for trout. Our study shows how density-dependent and environmental factors can interact to determine the survival of marble trout during the first year of life. 相似文献
19.
Eradication of the invasive Pseudorasbora parva results in increased growth and production of native fishes 总被引：1，自引：0，他引：1
Abstract – The topmouth gudgeon, Pseudorasbora parva , has been described as Europe's most invasive fish. To control their UK invasion, some lentic populations at risk of causing fluvial dispersal have been eradicated. The first of these operations was from a lake in north-west UK in March 2005 using rotenone application; prior to eradication, their mean density was estimated as 6.1 m−2 whereas since eradication, no P . parva have been recorded. Prior to rotenone application, the majority of native fishes were removed, held off-site and reintroduced following degradation of rotenone to safe levels. In the three growth seasons since their reintroduction and P . parva eradication, the abundance, somatic growth rate and production of roach Rutilus rutilus and common bream Abramis brama have increased significantly; production is now driven by a lower number of comparatively larger, faster growing individuals. These data suggest that the eradication of this P . parva population has been highly beneficial for the growth, recruitment and production of these native species. 相似文献
20.
C. Tudorache P. Viaene R. Blust H. Vereecken G. De Boeck 《Ecology of Freshwater Fish》2008,17(2):284-291
Abstract – Migrating fish species with different swimming capacities and energy use show different capacities for passing obstacles between habitats, such as culverts and fish ladders. Here, we present an integrated study on swimming capacity and energetic use in seven European freshwater fish species with different ranges of migration (brown trout Salmo trutta L., European perch Perca fluviatilis L., roach Rutilus rutilus L., common carp Cyprinus carpio L., gudgeon Gobio gobio L., bullhead Cottus gobio L. and stone loach Barbatula barbatula L.). Critical ( U crit ), optimal ( U opt ) and maximum ( U max ) swimming speed and oxygen consumption ( M O2 ) were analysed and showed values correlated to migration capacity with highest swimming capacities in trout and roach and lowest in stone loach and bullhead. The resulting data can be used to make estimates of maximum passable water speeds in culverts. In conclusion, long-distance migrators show higher swimming capacities and can potentially clear obstacles easier than short distance migrators with lower swimming capacities. Even small obstacles (<25 cm) could be a barrier for genetic exchange between populations in short-distance migrators. 相似文献