PREDICTING VULNERABILITY OF FISHES by Stacey Lee O’Malley A thesis submitted in conformity with the requirements for the degree of Master of Science Department of Ecology and Evolutionary Biology University of Toronto © Copyright by Stacey O’Malley 2010 Predicting Vulnerability of Fishes Stacey Lee O’Malley Master of Science Department of Ecology and Evolutionary Biology University of Toronto 2010 Abstract Conservation biology would benefit from methods that identify species at risk in a proactive manner, rather than through post-hoc conservation assessments. This study examines the utility of four potential indices for predicting vulnerability in fishes: total body length; trophic level; intrinsic vulnerability score; and, resilience. Statistical analysis was done to determine if correlations existed between any of these four indices and known levels of risk in marine and freshwater Canadian fishes. Results show the success of two of these indices to predict risk: fished species over 78.33 centimeters total length, or with intrinsic vulnerability scores over 57.41 are more highly vulnerable to becoming at risk. Over 20% of Canadian fished species of unknown conservation status are therefore currently vulnerable, and possibly at risk of extinction. This study shows vulnerability indices allow a rapid prioritization of fishes at risk of extinction, and can thus help achieve proactive conservation even in the absence of population decline data. ii Acknowledgements Firstly, I would like to thank my supervisor Prof. Mart Gross for his support, guidance and assistance throughout the duration of my work at the University of Toronto, and for inspiring me to pursue graduate studies in conservation biology. Mart, more than anyone else you have expanded my thinking about conservation issues, and you have helped me to realize my potential to make a difference as a conservation biologist. Thank you. I thank the David Suzuki Foundation (DSF) for their partnership through the NSERC Industrial Postgraduate Scholarship program. I would like to thank Dr. Scott Wallace, Sustainable Fisheries Analyst at DSF for his supervisory support, as well as the Marine Conservation Team and the rest of the DSF staff for welcoming me into their office and community. My lab members have provided me the opportunity to discuss the work presented here, and I thank Blake Turner, Eric Davies, Dan Clarke, Sandra Neill, Kristen Hahn and Sarah Hasnain. Additionally, I thank my supervisory committee members Dr. Lisa Manne and Douglas Macdonald, PhD. who have assisted in focusing my research. I thank as well Dr. Don Jackson, Dr. Brian Shuter and Dr. Joe Repka for discussions on statistics and mathematics, as well as graduate students Brie Edwards, Monica Granados and Bronwyn Rayfield. Finally, I would like to extend appreciation to my friends and family for their support and encouragement. I particularly thank Amy Stevens Yee and Duane Petts for their editing assistance. iii Table of Contents List of Tables ................................................................................................................................. vi List of Figures............................................................................................................................... vii List of Appendices ....................................................................................................................... viii Predicting Vulnerability of Fishes .................................................................................................. 1 1 Introduction................................................................................................................................ 1 2 Materials and Methods............................................................................................................... 3 2.1 Overall analytical design..................................................................................................... 3 2.2 Data sources........................................................................................................................ 4 2.3 Vulnerability indices and categories................................................................................... 5 Body size (SIZE)................................................................................................................. 5 Trophic level (TROP) ......................................................................................................... 5 Intrinsic vulnerability score (IVUL) ................................................................................... 6 Resilience (RESL) .............................................................................................................. 6 2.4 Statistical analyses and comparisons .................................................................................. 7 3 Results........................................................................................................................................ 9 3.1 Comparative overview........................................................................................................ 9 3.2 Predictive capacity of indices ........................................................................................... 10 Predictive success ............................................................................................................. 10 3.3 Predictive capacity by cause of endangerment ................................................................. 11 Predictive success ............................................................................................................. 12 3.4 Misclassifications.............................................................................................................. 12 3.5 Predicting vulnerability of Canada’s fishes ...................................................................... 13 4 Discussion ................................................................................................................................ 13 iv 4.1 What makes an index successful?..................................................................................... 14 4.2 Why do indices work for some species and not others? ................................................... 17 4.3 Uncertainty and misclassification..................................................................................... 18 False positives................................................................................................................... 18 False negatives.................................................................................................................. 19 4.4 Data considerations........................................................................................................... 20 4.5 Predicting Vulnerability in Canada’s Fish Fauna ............................................................. 21 4.6 Conclusions....................................................................................................................... 22 References..................................................................................................................................... 24 Tables............................................................................................................................................ 29 Figures........................................................................................................................................... 39 Appendices.................................................................................................................................... 46 v List of Tables • Table 1. Vulnerability index values for Canadian fish species at risk and not at risk. • Table 2. Spearman correlations between vulnerability index values for assessed Canadian fish species (at risk and not at risk), n=166. • Table 3. Analysis of variance (ANOVA) examining effects of external variables on capacity for vulnerability indices to predict risk. • Table 4. Capacity for vulnerability indices to predict Canadian fish species at risk: cross- validated logistic regression output. • Table 5. Threshold values of body size (maximum length) and intrinsic vulnerability score in predicting Canadian fish species at risk and not at risk, as determined by cross-validated logistic analysis. • Table 6. Extrinsic threats to Canadian fishes. • Table 7. Capacity for vulnerability indices to predict Canadian fish species at risk under particular extrinsic threats. • Table 8. Cross-validated threshold values for species’ vulnerability to fishing related threats. • Table 9. Cross-validated threshold values for species’ vulnerability to overfishing and bycatch threats. • Table 10. Species misclassified by both body size and intrinsic vulnerability indices at probability cutoff point 0.5. vi List of Figures • Figure 1. Conservation-assessed Canadian fish species (n=166) that are at risk or not-at- risk of extinction, classified by fishing and environment type. • Figure 2. Classification success of vulnerability indices to predict risk, using cross- validated models in receiver-operating characteristic (ROC) space. • Figure 3. Classification success of vulnerability indices to predict under the threat of fishing in Canadian fish species, using cross-validated models in receiver-operating characteristic (ROC) space. • Figure 4. Frequency distribution and vulnerability of fished Canadian species of unknown risk status. vii List of Appendices • Appendix 1.