Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 7-Day Trial for You or Your Team.

Learn More →

Mean Size at Age: An Evaluation of Sampling Strategies with Simulated Red Grouper Data

Mean Size at Age: An Evaluation of Sampling Strategies with Simulated Red Grouper Data The influence of sampling protocol on estimation of mean lengths at age was evaluated by computer simulation of a population of red grouper Epinephelus morio. Variation in length at age was simulated with platoons of different lengths within each year‐class. Mean length of each platoon was assigned with the normal distribution and mean size at age from a previous growth study. Natural mortality was assumed to be 0.2. Simulated samples were obtained at random or with length stratification from either the population or its fishery. Fishing mortality was assumed to be a function of either fish age or fish length. Estimates of mean length at age contrasted with known true mean lengths indicated that reliable estimates of mean size at age requires random sampling of lengths within ages. Stratification of samples by length biases the estimates of mean length at age. Similarly, samples drawn from size‐selective gears or fisheries yield biased estimates of mean length at age. Growth models fitted to such data will not generally reflect the mean growth of individuals in the population, and even slight changes in sampling protocol can result in misleading temporal shifts of estimates of size at age. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Transactions of the American Fisheries Society Oxford University Press

Mean Size at Age: An Evaluation of Sampling Strategies with Simulated Red Grouper Data

Download PDF
10 pages

Loading next page...
 
/lp/oxford-university-press/mean-size-at-age-an-evaluation-of-sampling-strategies-with-simulated-Bxv9TPY367

References (0)

References for this paper are not available at this time. We will be adding them shortly, thank you for your patience.

Publisher
Oxford University Press
Copyright
© American Fisheries Society
ISSN
0002-8487
eISSN
1548-8659
DOI
10.1577/1548-8659(1995)124<0746:msaaae>2.3.co;2
Publisher site
See Article on Publisher Site

Abstract

The influence of sampling protocol on estimation of mean lengths at age was evaluated by computer simulation of a population of red grouper Epinephelus morio. Variation in length at age was simulated with platoons of different lengths within each year‐class. Mean length of each platoon was assigned with the normal distribution and mean size at age from a previous growth study. Natural mortality was assumed to be 0.2. Simulated samples were obtained at random or with length stratification from either the population or its fishery. Fishing mortality was assumed to be a function of either fish age or fish length. Estimates of mean length at age contrasted with known true mean lengths indicated that reliable estimates of mean size at age requires random sampling of lengths within ages. Stratification of samples by length biases the estimates of mean length at age. Similarly, samples drawn from size‐selective gears or fisheries yield biased estimates of mean length at age. Growth models fitted to such data will not generally reflect the mean growth of individuals in the population, and even slight changes in sampling protocol can result in misleading temporal shifts of estimates of size at age.

Journal

Transactions of the American Fisheries Society – Oxford University Press

Published: Sep 1, 1995

There are no references for this article.