Using R for Modelling and Quantitative Methods in Fisheries Chapman & Hall/CRC The R Series Series Editors John M. Chambers, Department of Sta(cid:127)s(cid:127)cs, Stanford University, California, USA Torsten Hothorn, Division of Biosta(cid:127)s(cid:127)cs,University of Zurich,Switzerland Duncan Temple Lang, Department of Sta(cid:127)s(cid:127)cs,University of California, Davis, USA Hadley Wickham, RStudio, Boston, Massachuse!s, USA Recently Published Titles Sta!s!cal Compu!ng with R, Second Edi!on Maria L. Rizzo Geocomputa!on with R Robin Lovelace, Jakub Nowosad, Jannes Muenchow Advanced R, Second Edi!on Hadley Wickham Dose Response Analysis Using R Chris!an Ritz, Signe Marie Jensen, Daniel Gerhard, Jens Carl Streibig Distribu!ons for ModellingLoca!on,Scale,and Shape Using GAMLSS in R Robert A. Rigby, Mikis D. Stasinopoulos, Gillian Z. Heller, Fernanda De Bas!ani Hands-On Machine Learning with R Bradley Boehmke and Brandon Greenwell Sta!s!cal Inference via Data Science A ModernDiveintoR and the Tidyverse Chester Ismay and Albert Y. Kim Reproducible Researchwith R and RStudio, Third Edi!on Christopher Gandrud Interac!ve Web-Based Data Visualiza!on with R, plotly, and shiny Carson Sievert Learn R Pedro J. Aphalo Using R for Modelling and Quan!ta!ve Methods in Fisheries Malcolm Haddon For more informa(cid:127)on about this series, please visit: h!ps://www.crcpress.com/Chapman--HallCRC- The-R-Series/book-series/CRCTHERSER Using R for Modelling and Quantitative Methods in Fisheries Malcolm Haddon CSIRO, Oceans and Atmosphere, Hobart IMAS, University of Tasmania CRCPress Taylor&FrancisGroup 6000BrokenSoundParkwayNW,Suite300 BocaRaton,FL33487-2742 ©2021byTaylor&FrancisGroup,LLC CRCPressisanimprintofTaylor&FrancisGroup,anInformabusiness NoclaimtooriginalU.S.Governmentworks Printedonacid-freepaper InternationalStandardBookNumber-13:978-0-367-46989-4(Hardback) 978-0-367-46988-7(Paperback) Thisbookcontainsinformationobtainedfromauthenticandhighlyregardedsources.Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannotassumeresponsibilityforthevalidityofallmaterialsortheconsequencesoftheiruse.The authorsandpublishershaveattemptedtotracethecopyrightholdersofallmaterialreproduced in this publication and apologize to copyright holders if permission to publish in this form has notbeenobtained.Ifanycopyrightmaterialhasnotbeenacknowledgedpleasewriteandletus knowsowemayrectifyinanyfuturereprint. 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Library of Congress Cataloging-in-Publication Data Names:Haddon,Malcolm,author. Title: Using R for modelling and quantitative methods in fisheries / Malcolm Haddon. Description:BocaRaton:CRCPress,[2021]|Summary:“Thebookhasevolved and adapted from an earlier book by the same author and provides a detailed introduction to analytical methods commonly used by fishery scientists, ecolo- gists,andadvancedstudentsusingtheopensourcesoftwareRasaprogramming tool”--Providedbypublisher. Identifiers: LCCN 2020014277 (print) | LCCN 2020014278 (ebook) | ISBN 9780367469894 (hardback) | ISBN 9780367469887 (paperback) | ISBN 9781003032601(ebook) Subjects: LCSH: Fisheries--Mathematical models. | R (Computer program language) Classification: LCC SH331.5.M48 H343 2021 (print) | LCC SH331.5.M48 (ebook)|DDC333.95/611015118--dc23 LCrecordavailableathttps://lccn.loc.gov/2020014277 LCebookrecordavailableathttps://lccn.loc.gov/2020014278 Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com Contents Preface xi 1 On Modelling 1 1.1 Characteristics of Mathematical Models . . . . . . . . . . . . 1 1.1.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1.2 Model Design or Selection . . . . . . . . . . . . . . . . 1 1.1.3 Constraints Due to the Model Type . . . . . . . . . . 3 1.1.4 Mathematical Models . . . . . . . . . . . . . . . . . . 3 1.1.5 Parameters and Variables . . . . . . . . . . . . . . . . 4 1.2 Mathematical Model Properties . . . . . . . . . . . . . . . . 5 1.2.1 Deterministic vs Stochastic . . . . . . . . . . . . . . . 5 1.2.2 Continuous vs Discrete Models . . . . . . . . . . . . . 6 1.2.3 Descriptive vs Explanatory . . . . . . . . . . . . . . . 7 1.2.4 Testing Explanatory Models . . . . . . . . . . . . . . . 8 1.2.5 Realism vs Generality . . . . . . . . . . . . . . . . . . 9 1.2.6 When Is a Model a Theory? . . . . . . . . . . . . . . . 10 1.3 Concluding Remarks . . . . . . . . . . . . . . . . . . . . . . 11 2 A Non-Introduction to R 13 2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2.2 Programming in R . . . . . . . . . . . . . . . . . . . . . . . . 13 2.2.1 Getting Started with R . . . . . . . . . . . . . . . . . 14 2.2.2 R Packages . . . . . . . . . . . . . . . . . . . . . . . . 15 2.2.3 Getting Started with MQMF . . . . . . . . . . . . . 16 2.2.4 Examining Code within Functions . . . . . . . . . . . 17 2.2.5 Using Functions . . . . . . . . . . . . . . . . . . . . . 18 2.2.6 Random Number Generation . . . . . . . . . . . . . . 19 2.2.7 Printing in R . . . . . . . . . . . . . . . . . . . . . . . 21 2.2.8 Plotting in R . . . . . . . . . . . . . . . . . . . . . . . 21 2.2.9 Dealing with Factors . . . . . . . . . . . . . . . . . . . 22 2.2.10 Inputting Data . . . . . . . . . . . . . . . . . . . . . . 24 2.3 Writing Functions . . . . . . . . . . . . . . . . . . . . . . . . 25 2.3.1 Simple Functions . . . . . . . . . . . . . . . . . . . . . 25 2.3.2 Function Input Values . . . . . . . . . . . . . . . . . . 27 2.3.3 R Objects . . . . . . . . . . . . . . . . . . . . . . . . . 28 2.3.4 Scoping of Objects . . . . . . . . . . . . . . . . . . . . 28 v vi Contents 2.3.5 Function Inputs and Outputs . . . . . . . . . . . . . . 29 2.4 Appendix: Less-Traveled Functions . . . . . . . . . . . . . . 33 2.5 Appendix: Additional Learning Resources . . . . . . . . . . . 33 3 Simple Population Models 35 3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 3.1.1 The Discrete Logistic Model. . . . . . . . . . . . . . . 35 3.1.2 Dynamic Behaviour . . . . . . . . . . . . . . . . . . . 37 3.1.3 Finding Boundaries between Behaviours . . . . . . . . 40 3.1.4 Classical Bifurcation Diagram of Chaos . . . . . . . . 42 3.1.5 The Effect of Fishing on Dynamics . . . . . . . . . . . 43 3.1.6 Determinism . . . . . . . . . . . . . . . . . . . . . . . 46 3.2 Age-Structured Modelling Concepts . . . . . . . . . . . . . . 48 3.2.1 Survivorship in a Cohort. . . . . . . . . . . . . . . . . 48 3.2.2 Instantaneous vs Annual Mortality Rates . . . . . . . 49 3.3 Simple Yield per Recruit . . . . . . . . . . . . . . . . . . . . 52 3.3.1 Selectivity in Yield-per-Recruit . . . . . . . . . . . . . 55 3.3.2 The Baranov Catch Equation . . . . . . . . . . . . . . 57 3.3.3 Growth and Weight-at-Age . . . . . . . . . . . . . . . 59 3.4 Full Yield-per-Recruit . . . . . . . . . . . . . . . . . . . . . . 60 3.5 Concluding Remarks . . . . . . . . . . . . . . . . . . . . . . 62 4 Model Parameter Estimation 65 4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 4.1.1 Optimization . . . . . . . . . . . . . . . . . . . . . . . 66 4.2 Criteria of Best Fit . . . . . . . . . . . . . . . . . . . . . . . 67 4.3 Model Fitting in R . . . . . . . . . . . . . . . . . . . . . . . 69 4.3.1 Model Requirements . . . . . . . . . . . . . . . . . . . 70 4.3.2 A Length-at-Age Example . . . . . . . . . . . . . . . . 71 4.3.3 Alternative Models of Growth . . . . . . . . . . . . . . 72 4.4 Sum of Squared Residual Deviations . . . . . . . . . . . . . . 73 4.4.1 Assumptions of Least-Squares . . . . . . . . . . . . . . 74 4.4.2 Numerical Solutions . . . . . . . . . . . . . . . . . . . 74 4.4.3 Passing Functions as Arguments to Other Functions . 75 4.4.4 Fitting the Models . . . . . . . . . . . . . . . . . . . . 77 4.4.5 Objective Model Selection . . . . . . . . . . . . . . . . 83 4.4.6 The Influence of Residual Error Choice on Model Fit . 84 4.4.7 Remarks on Initial Model Fitting . . . . . . . . . . . . 86 4.5 Maximum Likelihood . . . . . . . . . . . . . . . . . . . . . . 87 4.5.1 Introductory Examples. . . . . . . . . . . . . . . . . . 87 4.6 Likelihoods from the Normal Distribution . . . . . . . . . . . 90 4.6.1 Equivalence with Sum-of-Squares . . . . . . . . . . . . 92 4.6.2 Fitting a Model to Data Using Normal Likelihoods . . 94 4.7 Log-Normal Likelihoods . . . . . . . . . . . . . . . . . . . . . 98 4.7.1 Simplification of Log-Normal Likelihoods . . . . . . . 99 Contents vii 4.7.2 Log-Normal Properties . . . . . . . . . . . . . . . . . . 99 4.7.3 Fitting a Curve Using Log-Normal Likelihoods . . . . 102 4.7.4 Fitting a Dynamic Model Using Log-Normal Errors . 105 4.8 Likelihoods from the Binomial Distribution . . . . . . . . . . 108 4.8.1 An Example Using Binomial Likelihoods . . . . . . . . 109 4.8.2 Open Bay Juvenile Fur Seal Population Size. . . . . . 112 4.8.3 Using Multiple Independent Samples . . . . . . . . . . 114 4.8.4 Analytical Approaches . . . . . . . . . . . . . . . . . . 116 4.9 Other Distributions . . . . . . . . . . . . . . . . . . . . . . . 117 4.10 Likelihoods from the Multinomial Distribution . . . . . . . . 117 4.10.1 Using the Multinomial Distribution. . . . . . . . . . . 119 4.11 Likelihoods from the Gamma Distribution . . . . . . . . . . 125 4.12 Likelihoods from the Beta Distribution . . . . . . . . . . . . 127 4.13 Bayes’ Theorem . . . . . . . . . . . . . . . . . . . . . . . . . 128 4.13.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . 128 4.13.2 Bayesian Methods . . . . . . . . . . . . . . . . . . . . 130 4.13.3 Prior Probabilities . . . . . . . . . . . . . . . . . . . . 131 4.14 Concluding Remarks . . . . . . . . . . . . . . . . . . . . . . 134 5 Static Models 135 5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . 135 5.2 Productivity Parameters . . . . . . . . . . . . . . . . . . . . 136 5.3 Growth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136 5.3.1 Seasonal Growth Curves . . . . . . . . . . . . . . . . . 137 5.3.2 Fabens Method with Tagging Data . . . . . . . . . . . 142 5.3.3 Fitting Models to Tagging Data . . . . . . . . . . . . 144 5.3.4 A Closer Look at the Fabens Methods . . . . . . . . . 146 5.3.5 Implementation of Non-Constant Variances . . . . . . 148 5.4 Objective Model Selection . . . . . . . . . . . . . . . . . . . 151 5.4.1 Akiake’s Information Criterion . . . . . . . . . . . . . 151 5.4.2 Likelihood Ratio Test . . . . . . . . . . . . . . . . . . 153 5.4.3 Caveats on Likelihood Ratio Tests . . . . . . . . . . . 154 5.5 Remarks on Growth . . . . . . . . . . . . . . . . . . . . . . . 154 5.6 Maturity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155 5.6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . 155 5.6.2 Alternative Maturity Ogives. . . . . . . . . . . . . . . 157 5.6.3 The Assumption of Symmetry . . . . . . . . . . . . . 161 5.7 Recruitment . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 5.7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . 165 5.7.2 Properties of “Good” Stock Recruitment Relationships 166 5.7.3 Recruitment Overfishing . . . . . . . . . . . . . . . . . 167 5.7.4 Beverton and Holt Recruitment . . . . . . . . . . . . . 168 5.7.5 Ricker Recruitment. . . . . . . . . . . . . . . . . . . . 169 5.7.6 Deriso’s Generalized Model . . . . . . . . . . . . . . . 171 5.7.7 Re-Parameterized Beverton-Holt Equation . . . . . . . 172 viii Contents 5.7.8 Re-Parameterized Ricker Equation . . . . . . . . . . . 175 5.8 Selectivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175 5.8.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . 175 5.8.2 Logistic Selection . . . . . . . . . . . . . . . . . . . . . 176 5.8.3 Dome-Shaped Selection . . . . . . . . . . . . . . . . . 177 5.9 Concluding Remarks for Static Models . . . . . . . . . . . . 180 5.10 Appendix: Derivation of Fabens Transformation . . . . . . . 181 5.11 Appendix: Reparameterization of Beverton-Holt . . . . . . . 182 6 On Uncertainty 185 6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . 185 6.1.1 Types of Uncertainty. . . . . . . . . . . . . . . . . . . 185 6.1.2 The Example Model . . . . . . . . . . . . . . . . . . . 188 6.2 Bootstrapping . . . . . . . . . . . . . . . . . . . . . . . . . . 191 6.2.1 Empirical Probability Density Distributions . . . . . . 191 6.3 A Simple Bootstrap Example . . . . . . . . . . . . . . . . . . 192 6.4 Bootstrapping Time-Series Data . . . . . . . . . . . . . . . . 195 6.4.1 Parameter Correlation . . . . . . . . . . . . . . . . . . 199 6.5 Asymptotic Errors . . . . . . . . . . . . . . . . . . . . . . . . 200 6.5.1 Uncertainty about the Model Outputs . . . . . . . . . 203 6.5.2 Sampling from a Multivariate Normal Distribution . . 204 6.6 Likelihood Profiles . . . . . . . . . . . . . . . . . . . . . . . . 209 6.6.1 Likelihood Ratio-Based Confidence Intervals. . . . . . 212 6.6.2 -ve Log-Likelihoods or Likelihoods . . . . . . . . . . . 214 6.6.3 Percentile Likelihood Profiles for Model Outputs . . . 216 6.7 Bayesian Posterior Distributions . . . . . . . . . . . . . . . . 219 6.7.1 Generating the Markov Chain . . . . . . . . . . . . . . 221 6.7.2 The Starting Point . . . . . . . . . . . . . . . . . . . . 222 6.7.3 The Burn-In Period . . . . . . . . . . . . . . . . . . . 223 6.7.4 Convergence to the Stationary Distribution . . . . . . 223 6.7.5 The Jumping Distribution . . . . . . . . . . . . . . . . 224 6.7.6 Application of MCMC to the Example . . . . . . . . . 225 6.7.7 Markov Chain Monte Carlo . . . . . . . . . . . . . . . 225 6.7.8 A First Example of an MCMC . . . . . . . . . . . . . 228 6.7.9 Marginal Distributions . . . . . . . . . . . . . . . . . . 235 6.8 The Use of Rcpp . . . . . . . . . . . . . . . . . . . . . . . . . 236 6.8.1 Addressing Vectors and Matrices . . . . . . . . . . . . 239 6.8.2 Replacement for simpspm() . . . . . . . . . . . . . . . 240 6.8.3 Multiple Independent Chains . . . . . . . . . . . . . . 243 6.8.4 Replicates Required to Avoid Serial Correlation . . . . 247 6.9 Concluding Remarks . . . . . . . . . . . . . . . . . . . . . . 251 7 Surplus Production Models 253 7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 7.1.1 Data Needs . . . . . . . . . . . . . . . . . . . . . . . . 254 Contents ix 7.1.2 The Need for Contrast . . . . . . . . . . . . . . . . . . 254 7.1.3 When Are Catch-Rates Informative? . . . . . . . . . . 255 7.2 Some Equations . . . . . . . . . . . . . . . . . . . . . . . . . 259 7.2.1 Production Functions . . . . . . . . . . . . . . . . . . 261 7.2.2 The Schaefer Model . . . . . . . . . . . . . . . . . . . 263 7.2.3 Sum of Squared Residuals . . . . . . . . . . . . . . . . 264 7.2.4 Estimating Management Statistics . . . . . . . . . . . 265 7.2.5 The Trouble with Equilibria . . . . . . . . . . . . . . . 266 7.3 Model Fitting . . . . . . . . . . . . . . . . . . . . . . . . . . 267 7.3.1 A Possible Workflow for Stock Assessment . . . . . . . 268 7.3.2 Is the Analysis Robust? . . . . . . . . . . . . . . . . . 274 7.3.3 Using Different Data . . . . . . . . . . . . . . . . . . . 277 7.4 Uncertainty . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279 7.4.1 Likelihood Profiles . . . . . . . . . . . . . . . . . . . . 280 7.4.2 Bootstrap Confidence Intervals . . . . . . . . . . . . . 283 7.4.3 Parameter Correlations . . . . . . . . . . . . . . . . . 290 7.4.4 Asymptotic Errors . . . . . . . . . . . . . . . . . . . . 290 7.4.5 Sometimes Asymptotic Errors Work . . . . . . . . . . 297 7.4.6 Bayesian Posteriors. . . . . . . . . . . . . . . . . . . . 299 7.5 Management Advice . . . . . . . . . . . . . . . . . . . . . . . 308 7.5.1 Two Views of Risk . . . . . . . . . . . . . . . . . . . . 308 7.5.2 Harvest Strategies . . . . . . . . . . . . . . . . . . . . 309 7.6 Risk Assessment Projections . . . . . . . . . . . . . . . . . . 310 7.6.1 Deterministic Projections . . . . . . . . . . . . . . . . 310 7.6.2 Accounting for Uncertainty . . . . . . . . . . . . . . . 313 7.6.3 Using Asymptotic Errors . . . . . . . . . . . . . . . . 314 7.6.4 Using Bootstrap Parameter Vectors . . . . . . . . . . 316 7.6.5 Using Samples from a Bayesian Posterior . . . . . . . 316 7.7 Concluding Remarks . . . . . . . . . . . . . . . . . . . . . . 319 7.8 Appendix: The Use of Rcpp to Replace simpspm . . . . . . . 321 References 323 Index 335