摘要:

Atlantic permits were observed to break up and eat juvenile queen conches in an aquarium. It is suggested that this may occur in the wild more commonly than reported and may pose a threat to some conch seeding programmes.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1986.tb05149.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Breeding male ninespine sticklebacks,Pungilius pungitius, are highly aggressive toward juvenile brook charr.Salvelinus fontinalis, in the Matamek River, Québec. Field observations revealed that such aggression was always initiated by the sticklebacks and only if the charr approached their nests or free‐swimming fry. There was considerable overlap in diet in August, but not in June and July, suggesting competition for food is possible under some circumstances.In laboratory stream tanks, we compared frequency of intraspecific and interspecific aggression of single and mixed species groups over a range of densities. There was no simple relationship between aggression and density for either species, although significant differences in aggression occurred among fish in some of the different density conditio

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1986.tb05150.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Winter samples totalling 2308 specimens ofTrisopterus luscus(total length range: 13–36 cm) caught in northern Portugal were examined for infections withLernaeocera lusci.Infection prevalence was of 42%, and infection intensity was 1.7 copepods per infected fish. Individual infection varied between 1 and 9 copepods per infected specimen; 30.6% of the fish had bilateral parasitosis. There was a significant correlation (P0.05) and thus provide evidence thatL. luscihas no effect on the condition ofT. luscusin all the examined 1–cm size cl

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1986.tb05151.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

The diet of four species of the family Mormyridae, commonly found in the floodplain pools of the Sokoto‐Rima river basin, Nigeria, is described. All four species are small‐sized and show a degree of food overlap. Evidence is presented, however, that resource partitioning occurs enabling co‐existence of the species in a habitat where food resources become increasingly limited after the cessation of the

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1986.tb05152.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Several species belonging to different families of Brazilian freshwater fish are being studied cytogenetically, and the results obtained thus far have indicated interesting peculiarities. We show that karyotypic analysis, in addition to contributing to a better knowledge of the species, can also aid in their characterization, and we demonstrate the advantages of an associated cytogenetic‐taxonomic study, especially with respect to some groups of neotropical freshwater fish in Brazi

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1986.tb05153.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Two groups of largemouth bass,Micropterus salmoides, were reared in the laboratory. One group was reared on an artificial, passive diet (frozen brine shrimp) whereas the second was reared on a natural, active diet (cultured zooplankton). Observations on the development of feeding behaviour indicated that the motor patterns and duration (number of weeks in the behavioural repertoire) of the feeding acts did not differ between fry reared on the two diets. While feeding on their respective diets, natural‐diet fry performed significantly more orientations and bites, the two major early feeding acts, than did the artificial‐diet fry. When tested with live fish prey, fish reared on the natural diet performed fewer orientations and strikes and captured more prey per fry than did the artificial‐diet fry. Natural‐diet fry had a significantly better net efficiency (captures minus strikes minus orientations) than did artificial‐diet fry. Diet, experience, and length (T.L.) of fry affected their predator efficiency significantly. We argue that providing hatchery‐reared bass fry with an opportunity to prey on live forage fish once or twice before their release would enhance their survival and eventual recruitment into natural

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1986.tb05154.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

The influence of temperature on the embryonic development of three European cyprinid fishes,Abramis brama, Chalcalburnus chalcoides mentoandVimba vimba, was studied with respect to hatching efficiency and the functional relationship with the duration of development. The functional dependance of the duration of development on temperature is well described by a power function with a correcting constant for temperature. Comparison with published data for other cyprinids shows that the response of embryos to temperature, together with the various temperature controlled responses of adult fishes, is a valuable aid for the ecological characterization of the different species.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1986.tb05155.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Plerocercoids of the tapewormLigula intestinalisare reported from a salmonid,Salmo gairdneri, and an eleotrid,Gobiomorphus cotidianus, in New Zealand for the first time. There was no significant difference in condition factors between infected and uninfected trout. The prevalence of infection in bullies sampled increased with total length.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1986.tb05156.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Groups of cod,Gadus morhua(L.), were fed exclusively on fish, crustaceans, or crustacean shells for a period of 3 weeks. Chitinase and ß‐glucosidase activities were measured in enzyme extracts of stomach contents, stomach tissue, pyloric caeca, intestinal contents, and intestine tissue, and compared to the enzyme activities of control fish starved over the same period. Fulton's condition factorK, liver lipid content and liver water content were determined to estimate the effects of the diets on the condition of cod.general, the highest chitinase activities were measured in samples of cod that had been fed on whole crustaceans. In this feeding group, there was also a remarkable increase of activity by a factor of four to eight in the pyloric caeca, compared to the group fed on fish and the control group, respectively.Measurements of ß‐glucosidase activity revealed no similar dependence on food quality, ß‐glucosidase occurrence seemed to be mainly restricted to the pyloric caeca and the intestin

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1986.tb05157.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Young‐of‐the‐yearPseudopleuronectes americanuswere captured in Sandy Hook Bay, New Jersey and maintained in aquaria at 16–19° C for 115 days in 1982 and 127 days in 1983. Half of them were experimentally exposed toGlugea stephaniand the others were sham exposed. During the course of these experiments fish from both groups died as a result of G.stephaniinfection, demonstratingGlwgea‐induced mortality in this species. Infections were found in both control and experimentally exposed fish. Mortality ofGlwgea‐infected fish in the exposed group was 63% while that in the contro

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1986.tb05158.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY