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Quantifying precision of in situ length and weight measurements of fish

North American Journal of Fisheries Management

Abstract has subscript/superscript to be fixed
By:
and
DOI: 10.1577/1548-8675(1994)014<0318:QPOISL>2.3.CO;2

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Abstract

We estimated and compared errors in field-made (in situ) measurements of lengths and weights of fish. We made three measurements of length and weight on each of 33 common carp Cyprinus carpio, and on each of a total of 34 bluegills Lepomis macrochirus and black crappies Pomoxis nigromaculatus. Maximum total lengths of all fish were measured to the nearest 1 mm on a conventional measuring board. The bluegills and black crappies (85–282 mm maximum total length) were weighed to the nearest 1 g on a 1,000-g spring-loaded scale. The common carp (415–600 mm maximum total length) were weighed to the nearest 0.05 kg on a 20-kg spring-loaded scale. We present a statistical model for comparison of coefficients of variation of length (Cl ) and weight (Cw ). Expected Cl was near zero and constant across mean length, indicating that length can be measured with good precision in the field. Expected Cw decreased with increasing mean length, and was larger than expected Cl by 5.8 to over 100 times for the bluegills and black crappies, and by 3 to over 20 times for the common carp. Unrecognized in situ weighing errors bias the apparent content of unique information in weight, which is the information not explained by either length or measurement error. We recommend procedures to circumvent effects of weighing errors, including elimination of unnecessary weighing from routine monitoring programs. In situ weighing must be conducted with greater care than is common if the content of unique and nontrivial information in weight is to be correctly identified.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Quantifying precision of in situ length and weight measurements of fish
Series title:
North American Journal of Fisheries Management
DOI:
10.1577/1548-8675(1994)014<0318:QPOISL>2.3.CO;2
Volume
14
Issue:
2
Year Published:
1994
Language:
English
Publisher:
Taylor & Francis
Publisher location:
Philadelphia, PA
Contributing office(s):
Upper Midwest Environmental Sciences Center
Description:
5 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
North American Journal of Fisheries Management
First page:
318
Last page:
322
Number of Pages:
5