Minimum viable population size for lake sturgeon (Acipenser fulvescens) using an individual-based model of demographics and genetics

Abstract

Population viability analysis is a useful tool to explore the relationship between extinction risk and population size, but often does not include genetic factors. Our objectives were to determine minimum viable population size (MVP) for lake sturgeon (Acipenser fulvescens) and examine how inbreeding depression may affect MVP. Our individual-based model incorporated inbreeding depression in two ways: individuals with inbreeding coefficients above a threshold experienced inbreeding depression (threshold), and individuals experienced inbreeding depression at a rate related to their inbreeding coefficient (gradual). Three mechanisms relating inbreeding to fitness were explored (young-of-the-year (YOY) viability, post-YOY viability, number of progeny). The criterion we used to determine MVP was a 5% chance of extinction over 250 years. The estimated MVP without inbreeding effects was 80 individuals. For some scenarios incorporating inbreeding, MVP did not change, but for others, MVP was substantially higher, reaching values up to 1800. Results demonstrate that extinction risk and MVP can be influenced by both demographic stochasticity and inbreeding depression. This research should inform management by determining MVP and how inbreeding, which is expected to accrue in remnant populations because of generations of low abundance, may affect MVP.Résumé : L'analyse de la viabilité d'une population est un outil utile pour explorer la relation qui existe entre le risque d'extinction et la taille d'une population, mais souvent elle n'inclut pas les facteurs génétiques. Nos objectifs sont de déter-miner la taille minimale viable de la population (MVP) chez l'esturgeon jaune (Acipenser fulvescens) et l'effet potentiel de la dépression endogamique sur la MVP. Notre modèle basé sur l'individu incorpore la dépression endogamique de deux façons : les individus qui possèdent un coefficient d'endogamie au-dessus d'un certain seuil connaissent une dépression endogamique (seuil) et les individus connaissent une dépression endogamique à un taux proportionnel à leur coefficient d'endogamie (gradient). Nous avons exploré trois mécanismes qui relient l'endogamie à la fitness (la viabilité des jeunes de l'année (YOY), la viabilité après le stade YOY et le nombre de rejetons). Le critère que nous utilisons pour déterminer la MVP est une probabilité d'extinction de 5 % sur 250 ans. La MVP estimée sans les effets de l'endogamie est de 80 individus. Dans certains scénarios qui incorporent l'endogamie, MVP ne change pas, mais dans d'autres, la MVP est beaucoup plus élevée, pouvant atteindre des valeurs de l'ordre de 1800. Nos résultats démontrent que le risque d'extinction et la MVP peuvent être influencés par à la fois la stochasticité démographique et la dépression endogamique. Notre recherche devrait fournir des renseignements pour la gestion en déterminant la MVP et en montrant comment l'endogamie, qu'on s'attend à voir augmenter dans les populations résiduelles à cause de générations de faible abondance, peut affecter la MVP.[Traduit par ...

Retrospective weight-of-evidence analysis identifies substrate change as the apparent cause of recruitment failure in the upper Columbia River white sturgeon (Acipenser transmontanus)

“…335 locations. It may differ from the final official version of record.2000 mature fish; UCWSRI 2013) would exceed the low population thresholds identified by 380 theoretical evaluations for sturgeon(Jager et al 2010;Schueller and Hayes 2011). J.…”

Quantification of emigration and habitat use inform stocking rates of lake sturgeon (Acipenser fulvescens , Rafinesque, 1817) in the Cumberland River, Tennessee, USA

“…Quantifying emigration rates with a goal to maintain/establish a MVP are essential components in a recovery plan when evaluating stocking strategies. Management implications regarding temporal stock size as it pertains to Minimum Viable Population levels is critical to healthy populations (Reed & Bryant, ; Schueller & Hayes, ). Emigration and immigration of lake sturgeon through CDL and OHLD can occur by way of turbines, spillway gates, and locks.…”

“…In the Tennessee River system, studies indicate that stocked juvenile lake sturgeon show a general propensity to disperse downriver by way of dam passage (Collier et al., ; Huddleston et al., ). This tendency and ability have important potential management implications regarding temporal stock size as it pertains to Minimum Viable Population levels (MVP; Schueller & Hayes, ). And while studies of lake sturgeon (e.g.…”

“…Management implications regarding temporal stock size as it pertains to Minimum Viable Population levels is critical to healthy populations(Reed & Bryant, 2000;Schueller & Hayes, 2011).Emigration and immigration of lake sturgeon through CDL and OHLD can occur by way of turbines, spillway gates, and locks. The study design used herein did not focus on the specifics of each passage event, but only at which passage it occurred and at what rate.…”

Find the weakest link. A comparison between demographic, genetic and demo-genetic metapopulation extinction times

“…Important fields of application are (i) the definition of MVPs, which should differ according to whether ecological [22] or genetic [13] processes are considered. Recent examples include demo-genetic modeling of lake sturgeon populations, indicating that MVP estimates are strongly underestimated if the effects of inbreeding are neglected [23]; (ii) solving potential antagonism between genetic and demographic aspects in metapopulations [24] and considering genetic connectivity in reserve design (see an example on the jaguar in ref. [25]) (iii) help defining optimal strategies in conservative restoration or supplementation programs [26,27].…”