Estimating fishing and natural mortality rates, and catchability coefficient, from a series of observations on mean length and fishing effort
Gedamke and Hoenig (2006) (Transactions of the American Fisheries Society, 135: 476-487) developed a non-equilibrium version of the Beverton and Holt estimator of total mortality rate, Z, based on mean length and thereby increased the usefulness of length-based methods. In this study, we extend thei...
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| Format: | Article |
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Oxford University Press
2017
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| _version_ | 1825721506401878016 |
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| author | Then, Amy Yee Hui Hoenig, John Maurice Huynh, Quang C |
| author_facet | Then, Amy Yee Hui Hoenig, John Maurice Huynh, Quang C |
| author_sort | Then, Amy Yee Hui |
| collection | UM |
| description | Gedamke and Hoenig (2006) (Transactions of the American Fisheries Society, 135: 476-487) developed a non-equilibrium version of the Beverton and Holt estimator of total mortality rate, Z, based on mean length and thereby increased the usefulness of length-based methods. In this study, we extend their model by replacing period-specific Z parameters with the year-specific parameterization Z y = qf y + M where q is the catchability coefficient, f y is the fishing effort in year y, F (=qf) is the fishing mortality rate, and M is the natural mortality rate. Thus, the problem reduces to estimating just three parameters: q, M and residual variance. We used Monte Carlo simulation to study the model behaviour. Estimates of q and M are highly negatively correlated and may or may not be reliable; however, the estimates of corresponding Z's are more precise than estimates of F and are generally reliable, even when uncertainty about the mean lengths is high. This length-based method appears to work best for stocks with rapid growth rate. Contrast in effort data may not be necessary for reliable estimates of Z's. This approach forms a bridge between data-limited models and more complex models. We apply the method to the Norway lobster Nephrops norvegicus stock in Portugal as an example. |
| first_indexed | 2024-03-06T05:51:20Z |
| format | Article |
| id | um.eprints-20481 |
| institution | Universiti Malaya |
| last_indexed | 2024-03-06T05:51:20Z |
| publishDate | 2017 |
| publisher | Oxford University Press |
| record_format | dspace |
| spelling | um.eprints-204812019-02-25T07:08:31Z http://eprints.um.edu.my/20481/ Estimating fishing and natural mortality rates, and catchability coefficient, from a series of observations on mean length and fishing effort Then, Amy Yee Hui Hoenig, John Maurice Huynh, Quang C Q Science (General) QH Natural history Gedamke and Hoenig (2006) (Transactions of the American Fisheries Society, 135: 476-487) developed a non-equilibrium version of the Beverton and Holt estimator of total mortality rate, Z, based on mean length and thereby increased the usefulness of length-based methods. In this study, we extend their model by replacing period-specific Z parameters with the year-specific parameterization Z y = qf y + M where q is the catchability coefficient, f y is the fishing effort in year y, F (=qf) is the fishing mortality rate, and M is the natural mortality rate. Thus, the problem reduces to estimating just three parameters: q, M and residual variance. We used Monte Carlo simulation to study the model behaviour. Estimates of q and M are highly negatively correlated and may or may not be reliable; however, the estimates of corresponding Z's are more precise than estimates of F and are generally reliable, even when uncertainty about the mean lengths is high. This length-based method appears to work best for stocks with rapid growth rate. Contrast in effort data may not be necessary for reliable estimates of Z's. This approach forms a bridge between data-limited models and more complex models. We apply the method to the Norway lobster Nephrops norvegicus stock in Portugal as an example. Oxford University Press 2017 Article PeerReviewed Then, Amy Yee Hui and Hoenig, John Maurice and Huynh, Quang C (2017) Estimating fishing and natural mortality rates, and catchability coefficient, from a series of observations on mean length and fishing effort. ICES Journal of Marine Science, 75 (2). pp. 610-620. ISSN 1054-3139, DOI https://doi.org/10.1093/icesjms/fsx177 <https://doi.org/10.1093/icesjms/fsx177>. https://doi.org/10.1093/icesjms/fsx177 doi:10.1093/icesjms/fsx177 |
| spellingShingle | Q Science (General) QH Natural history Then, Amy Yee Hui Hoenig, John Maurice Huynh, Quang C Estimating fishing and natural mortality rates, and catchability coefficient, from a series of observations on mean length and fishing effort |
| title | Estimating fishing and natural mortality rates, and catchability coefficient, from a series of observations on mean length and fishing effort |
| title_full | Estimating fishing and natural mortality rates, and catchability coefficient, from a series of observations on mean length and fishing effort |
| title_fullStr | Estimating fishing and natural mortality rates, and catchability coefficient, from a series of observations on mean length and fishing effort |
| title_full_unstemmed | Estimating fishing and natural mortality rates, and catchability coefficient, from a series of observations on mean length and fishing effort |
| title_short | Estimating fishing and natural mortality rates, and catchability coefficient, from a series of observations on mean length and fishing effort |
| title_sort | estimating fishing and natural mortality rates and catchability coefficient from a series of observations on mean length and fishing effort |
| topic | Q Science (General) QH Natural history |
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