Premium
Validation of the Scale Method for Estimating Age and Growth of Bluegills
Author(s) -
Regier Henry A.
Publication year - 1962
Publication title -
transactions of the american fisheries society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 86
eISSN - 1548-8659
pISSN - 0002-8487
DOI - 10.1577/1548-8659(1962)91[362:votsmf]2.0.co;2
Subject(s) - scale (ratio) , statistics , annulus (botany) , mathematics , biology , geography , cartography , botany
Bluegill age and growth data were obtained from 24 small farm ponds near Ithaca, New York. Criteria for annulus recognition were developed from scales of known‐age bluegills which consisted of original stock in the ponds. Twelve separate criteria permitted recognition of annuli in nearly all samples. The 24 body‐scale relationships estimated in the present study were compared with 18 relationships determined by 10 other authors after units of measurement had been standardized. Body‐scale relationships were found to be approximately rectilinear for the key‐scale area used in this study except for bluegills below 1.5 inches. The hypothesis that differences between intercepts (i.e., correction factors) were due only to chance variation was tested and rejected. From a practical standpoint, however, inaccuracies resulting from use of an average intercept were found to be negligible. Bluegills occasionally fail to form annuli near the focus or at the margin. Validity of annulus determination and back‐calculation were examined by comparing back‐calculated lengths with observed lengths in previous years for each of 24 populations. Poor agreement was found in segments of four populations, and acceptable agreement otherwise. The scale method, as applied in this study, was generally valid for age and growth determinations of bluegills.