Research Document 2021/025

Recovery Potential Modelling of Lake Sturgeon (Acipenser fulvescens) in Canada

By van der Lee, A.S. and Koops, M.A.

Abstract

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) has assessed the Lake Sturgeon (Acipenser fulvescens) across 4 designatable units (DU) as Endangered in DUs 1 and 2, Threatened in DU 4 and Special Concern in DU 3. Here population modelling, using a female only matrix model, is presented to determine population-based recovery targets, assess the impact of anthropogenic harm, and conduct long-term projections of population recovery in support of a recovery potential assessment (RPA) for Lake Sturgeon populations in Canada. Simulations were conducted for populations with 5 distinct growth patterns characterized by their rate of growth and maximum size to incorporate the diversity in life-history characteristics expected across Canada. Populations with slower growth were estimated to have greater adult survival rates (~ 95%) and resultantly greater generation times (> 50 years) relative to faster growth sturgeon populations (~ 92% and ~ 30 years). Patterns in elasticity estimates were similar across growth types. Under most scenarios population growth rate (λ) was most sensitive to changes to survival of young adults (age 26–62). The exception to this was populations experiencing continued reduced adult survival (leading to population decline); which were most sensitive to changes to the survival rate of older juveniles (age 13–25). This indicates the importance of understanding the current stresses and the age distribution of a population when considering harm or determining what recovery actions to take. To achieve demographic sustainability, (i.e., a self-sustaining population over the long term) under conditions with a catastrophe probability of 0.15/generation and a quasi-extinction threshold of 25 adult females at a 1% probability of extinction over 250 years, population sizes ranging from 1,255–4,840 adult females were required. Populations with faster growth required larger population sizes (~ 5,000) to achieve demographic sustainability as their lower generation times resulted in increased frequency of catastrophic population decline (a 50% decline every 200–250 years compared to 340–360 years for slow growth Lake Sturgeon). MVP population size required between 550–>13,000 ha of lake habitat and 162–3,800 ha of river habitat (inclusive of both sexes and all age classes). Recovery times are variable, dependent on initial population size and the rate of population growth.

Research Document 2021/025 (PDF, 4,092 KB)

Accessibility Notice

This document is available in PDF format. If the document is not accessible to you, please contact the Secretariat to obtain another appropriate format, such as regular print, large print, Braille or audio version.