摘要:

Checks were formed on the scales in June and July. A dominant 1959 year class accounted for half the population present in 1964. Females grew faster than males and attained greater ultimate size. Growth in the River Lugg was good in comparison with rates in other British waters. The sex ratio was found to change with age; a predominance of males in the youngest age classes changed to a preponderance of females in the older classes. The youngest fishes caught (3+) were already sexually mature. The gonads were found to be a constant proportion of the body weight for fishes of all sizes at a given season. Spawning was completed by June; males were ripe in May. The ovaries recovered more rapidly than the testes after spawning. Seasonal variation in feeding activity, with higher activity in summer, was observed and could be correlated with temperature. Seasonal changes in the diet could be related to availability. The diet was predominantly vegetable; the most important animal component, aquatic insect larvae, accounted for 11 % of the total diet. Aerial insects were rarely eaten. Diet varied with age: molluscs being particularly important to older roach; younger roach consumed large amounts of substrate material. There is some evidence that young roach indiscriminately ingest substrate material but older roach are more selective and reject inert material.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1972.tb05696.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

In recent years, blood group and protein polymorphisms in Atlantic salmon have been investigated extensively with a view, primarily, to their use in identifying individuals of different spawning populations present in high seas fisheries. Erythrocyte antigens, haemoglobins, serum proteins and various tissue enzymes—mainly esterases and de‐hydrogenases—have been studied by electrophoretic and immunological techniques. These studies are reviewed here for the first time.Many of the protein systems exhibit multiple components and this fact, together with cytological evidence, indicates the occurrence of tetraploidy in the course of Salmonid evolution. The significance of a tetraploid origin in the evolution and ecological adaptation of Salmonids is discussed briefly.Some protein systems studied exhibit phylogenetic variation, and analyses of phenotype ratios and allele frequencies indicate that the populations of different river systems are genetically distinct. Allele frequencies have not yet been shown to be stable from generation to generation however, and some of the factors likely to affect allele frequencies are discussed.Different spawning populations can not be identified in high seas fisheries using these protein characters, although it may be possible to identify the continent of origin (N. America or Europe) of some individuals. Indeed, it has been proposed independently by two groups that North American and European populations of Atlantic salmon be assigned to different sub‐species viz.S. s. americanusandS. s. europaeusrespectively. The contradictory evidence on which these taxa are proposed is discussed, together with the evidence for other population groups proposed in the European part of the salmon's range. The possible role and future direction of studies on the biochemical genetics of salmon are o

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1972.tb05697.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1972.tb05698.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

The biology of the population ofEthmalosa fimbriataoccurring in the Lagos lagoon was investigated. Three size groups, 35–69 mm (Yoyo), 70–169 mm (Efolo) and 170 mm and above (Agbodo) occur in the lagoon and the spatial distribution of these size groups and the length frequency distribution of the species is given. The relationship between length, weight, age and growth is discussed and the food and feeding intra‐relationship of the size groups is shown. Information on the fecundity and possible spawning periods is disc

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1972.tb05699.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

10 000 herrings from the commercial fisheries around the coasts of Great Britain and Ireland were examined for the nematode larvaAnisakissp. between October 1968 and October 1970. Heavy infestations were found in the North Sea stocks, moderate infestations west of Scotland and minimal infestations elsewhere; but nowhere was the parasite completely absent. Younger fish were often found to be more heavily infested than older fish and it is therefore suggested that the accumulation of larvae in the body cavity may be affected by annual fluctuations either in the population of an infested first intermediate host or in the extent to which the herrings are feeding on this host. A small but constant proportion of the parasites penetrate the musculature of the herring regardless of other factors such as the age or length of the host, or the number of other larvae present.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1972.tb05700.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Various parameters of the blood physiology of five South African species of fish have been investigated. The results show that plasma and serum samples differ in electrophoretic pattern, and also in the number of fractions and the protein concentration of these fractions. Red blood cell measurements, hemoglobin concentrations and blood glucose concentrations differ from fish to fish, and appear to be species specific. The values reported here are comparable with similar results obtained by other workers.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1972.tb05701.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

A total of 39 fish species has been introduced into European waters, mainly during the 19th and 20th centuries: 20 European species (12 successful), 3 Asian species (1 successful), 16 North American species (13 successful). Several successful introductions have produced unexpected and detrimental side‐effects; especially introductions of piscivorous species have created problems. Introductions of the latter type of fishes should be most carefully considered. The aim of fish introductions should preferably be to create temporary populations of non‐reproducing fishes whose numbers can be completely controlled by

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1972.tb05702.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Fractions of the pituitary extracts which were successfully used for induced spawning of certain carps have been tested in the present investigation to assess the gonadal hydration response in Lampam jawaPuntius gonionotus. The levels of major ions in the serum and seminal fluid were determined to see if there is any obvious change following the treatment. The gonadal hydration response was induced only by the injection of the second fraction, which fraction was thought to contain the gonadotropin or a gonadotropin releasing factor. A possible role of gonadotropin in osmoregulation has been indicated.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1972.tb05703.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

A review is made of some selected literature regarding the use of haematological techniques in freshwater fish pathology. Comparisons are drawn with the techniques already widely used in human pathology for the assessment of health and for aid in diagnosis of various diseases and conditions. The need for information on normal values, and on the conditions under which these were formulated, and the factors affecting them is stressed. The use of haematological values in assessing sublethal concentrations of environmental pollutants and the possibility of chromosomal changes are considered.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1972.tb05704.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AQUARIUM FISHES, THEIR BEAUTY, HISTORY AND CARE. Photographs by Douglas Faulkner. Text by James W. Atz.DISEASES OF FISH edited by S. F. Snieszko and H. R. Axelrod.DISEASES OF FISH edited by S. F. Snieszko and H. R.IBP HANDBOOK NO. 16. METHODS FOR THE STUDY OF MARINE BENTHOS edited by N. A. Holme and A. D. Mclntyre.METHODS IN AQUATIC MICROBIOLOGY by A. G. Rodina. Edited, translated and revised by R. R. Colwell and M. S. Zambruski.OCEANOGRAPHY‐Readings from Scientific American edited by J. Robert Moore.ADVANCES IN ECOLOGICAL RESEARCH edited by J. B. Cragg.GROWTH AND ECOLOGY OF FISH POPULATIONS by A. H. Weatherl

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1972.tb05705.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY