Journal ArticleDOI
The length-weight relationship and seasonal cycle in gonad weight and condition in the perch (perca fl uvia tilis)
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The present paper is an account of some of the investigations on the biology of the perch in Windermere, which are being conducted in connexion with a trap-fishery experiment, which revealed the relative complexity of the interrelationships of length, weight and condition.Abstract:
The present paper is an account of some of the investigations on the biology of the perch (Perca fluviatilis Linn.) in Windermere, which are being conducted in connexion with a trap-fishery experiment (Worthington, 1950). This experiment is mainly a study of populations, but it has been necessary simultaneously to investigate the general biology of the perch, particularly the growth and related aspects. The computation of a formula to express the length,weight relationship and provide a means of interconverting measurements of length and weight, revealed the relative complexity of the interrelationships of length, weight and condition. Condition in turn was found to be correlated with the seasonal changes in gonad development and growth, and the importance of the effect of stomach contents on weight had also to be assessed. It was decided, therefore, to combine these separate but interrelated aspects in one paper. The main part of the paper is devoted to the questions of length-weight relationship and condition. A brief review of the fundamental bases for the concepts of length-weight relationship and condition and of some of the methods of analysis of length-weight data precedes an account of the application of the chosen methods to the present material and its results. This is followed by an account of seasonal changes in gonad weights. A brief account is then given of the rather scanty data available on the weight of stomach contents. The seasonal changes in condition are then described and, finally, some of the results are summarized, combined and discussed as a picture of the seasonal cycle in the Windermere perch. In the statistical analysis of the length-weight relationship the data for only one group of fish are given in full (Tables i and 2) as an example of the method of computation used for all the groups. Again, in the section on seasonal changes in gonad weight and condition Figs. 2-7 are based partly on tables of data which are not published. The full tables have been deposited with the Freshwater Biological Association, from whom copies can be obtained.read more
Citations
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Journal ArticleDOI
Cube law, condition factor and weight-length relationships: history, meta-analysis and recommendations
TL;DR: A historical review, a meta-analysis, and recommendations for users about weight–length relationships, condition factors and relative weight equations are presented, indicating a tendency towards slightly positive-allometric growth (increase in relative body thickness or plumpness) in most fishes.
Journal ArticleDOI
Estimating fitness : a comparison of body condition indices
TL;DR: The residual index, with appropriate transformations to achieve homoscedasticity, was the most reliable index because it did not vary with body size, and it is recommended for general use in behavioral studies that require a condition estimate.
Journal ArticleDOI
The selection of suitable indices for the measurement and analysis of fish condition
T. Bolger,P. L. Connolly +1 more
TL;DR: A survey of the studies published in two leading fisheries journals revealed that the analysis and measurement of condition, based on length-weight data, has been performed using a wide variety of indices and statistical procedures.
Book ChapterDOI
Population Cycles in Small Mammals
Charles J. Krebs,Judith H. Myers +1 more
TL;DR: This chapter summarizes the current information on population cycles in small rodents, and first looks at the general questions about cycles, and then discusses the demographic machinery which drives the changes in numbers.
Journal ArticleDOI
Methods of Assessing Ovarian development in Fishes: a Review
Abstract: An important component of many studies of fish reproductive biology is the assessment of the stage of gonad development of individual fish. The methods in use vary from highly detailed to cursory, but there are few reviews of their reliability or usefulness. This review examines histology, measurements of oocyte size, staging based on the appearance of whole oocytes, staging based on the external appearance of the ovary, and gonad indices. Histology is the most accurate technique, but it is time- consuming and expensive. Staging based on the appearance of whole oocytes can be a useful alternative but may be inaccurate with oocytes in transitional stages of development. Staging based on the external appearance of the ovary is the simplest and most rapid method, but it may be subjective and its accuracy is uncertain. Oocyte size may be used as a predictor of developmental stage if the size ranges of the various stages are known, but the sizes of different oocyte stages may overlap, which complicates this approach. Oocyte size may be used on its own to measure development but gives little information on the physiological status of the ovaries. Gonad indices (gonad size relative to body size) provide a useful insight into changes in ovary size and complement results obtained using staging methods. However, gonad indices, like oocyte size, may be biased when samples of fish of different body sizes are compared.
References
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Book
On Growth and Form
TL;DR: This book is an application of some of the concepts of physical science and sundry mathematical methods to the study of organic form and is like one of Darwin's books, well-considered, patiently wrought-out, learned, and cautious.
Book
Problems of relative growth
TL;DR: This detailed study of the different rates of growth of parts of the body relative to the body as a whole represents Sir Julian Huxley's great contribution to analytical morphology, and it is still a basis for modern investigations in morphometrics and evolutionary biology.
Book
The mechanics of environmental control of body form in fishes
TL;DR: Direct evidence of the role of inflection in the determination of body form was found in natural populations and experimental lots of rainbow trout and the slope of relative-growth lines was altered experimentally by ~alnu~nlion' Relatively large head parts resulted.