Evaluating the consequences of common assumptions in run reconstructions on Pacific salmon biological status assessments

• Published in: Canadian journal of fisheries and aquatic sciences Vol. 77; no. 12; pp. 1904 - 1920
• Main Authors: Peacock, Stephanie J, Hertz, Eric, Holt, Carrie A, Connors, Brendan, Freshwater, Cameron, Connors, Katrina
• Format: Journal Article
• Language: English
• Published: 1840 Woodward Drive, Suite 1, Ottawa, ON K2C 0P7 NRC Research Press 01.12.2020; Canadian Science Publishing NRC Research Press
• Subjects: Abundance; Age; Assessments; Data analysis; Evaluation; Protection and preservation; Recovery plans; Salmon; Simulation; Stochasticity; Surveillance; Threatened species; Wildlife conservation; Canada
• ISSN: 0706-652X; 1205-7533
• DOI: 10.1139/cjfas-2019-0432

Information on biological status is essential for designing, implementing, and evaluating management strategies and recovery plans for threatened or exploited species. However, the data required to quantify status are often limited, and it is important to understand how assessments of status may be biased by assumptions in data analysis. For Pacific salmon, biological status assessments based on spawner abundances and spawner–recruitment (SR) analyses often involve “run reconstructions” that impute missing spawner data, expand observed spawner abundance to account for unmonitored streams, assign catch to individual stocks, and quantify age-at-return. Using a stochastic simulation approach, we quantified how common assumptions in run reconstructions biased assessments of biological status based on spawner abundance. We found that status assessments were robust to most common assumptions in run reconstructions, even in the face of declining monitoring coverage, but that overestimating catch tended to increase rates of status misclassification. Our results lend confidence to biological status assessments based on spawner abundances and SR analyses, even in the face of incomplete data.