Survival of Translocated Clubshell and Northern Riffleshell in Illinois

Abstract

Translocation of freshwater mussels is a conservation tool used to reintroduce extirpated populations or augment small populations. Few studies have evaluated the effectiveness of translocations, mainly because estimating survival is challenging and time-consuming. We used a mark-recapture approach to estimate survival of nearly 4,000 individually marked Clubshell (Pleurobema clava) and Northern Riffleshell (Epioblasma rangiana) translocated to eight sites over a five-year period into the Salt Fork and Middle Fork Vermilion rivers in central Illinois. Survival differed among sites and between species; Clubshell were approximately five times more likely to survive than Northern Riffleshell. Survival also increased in the fourth year following a release and decreased following high-flow events. Translocating numerous individuals into multiple sites over a period of years could spread the risk of catastrophic high-flow events and maximize the likelihood for establishing self-sustaining populations.

Reassessing Enigmatic Mussel Declines in the United States

“…disappeared from nearly their entire historical range, even from streams that continue to support otherwise healthy mussel faunas (e.g., Epioblasma rangiana, Pleurobema clava, P. rubrum; Haag and Cicerello 2016;Stodola et al 2017). These latter three types of declines are similar to enigmatic declines in that precise causes are unknown, but they differ in other ways, which I will describe subsequently.…”

“…Studies of this nature typically are conducted by housing mussels in enclosures. However, detailed monitoring of wild or reintroduced individuals and their responses to ambient conditions also provides opportunities to evaluate specific hypotheses about causes of mussel declines (e.g., Jones et al 2012;Clayton et al 2015;Stodola et al 2017). For example, assessing changes in individual mussel performance over time in response to management actions meant to reduce sediment could provide valuable information about the effectiveness of such actions.…”

Research priorities for freshwater mussel conservation assessment

“…Additionally, severe droughts associated with extreme temperatures can result in extremely low flows, with declines in species richness and local extirpations (Gagnon et al, 2004;Haag and Warren Jr., 2008;Sousa et al, 2018). In contrast, flooding due to extreme precipitation events can scour mussel beds, disrupt recruitment, or hinder species recovery efforts, such as translocations or reintroductions of endangered species (Strayer, 1999;Steuer et al, 2008;Haag, 2012;Stodola et al, 2017).…”

Freshwater mussels (Unionidae) brought into captivity exhibit up-regulation of genes involved in stress and energy metabolism

“…Some captive breeding programs maintain species threatened with extinction in zoos and aquaria for multiple generations to ensure their survival, with the goal of future reintroduction once threats to their existence have been removed 15 . Freshwater mussels are also often translocated to different habitats or brought into captive holding facilities for temporary refuge and propagation to mitigate damage from in-stream construction activities, toxic river spills, and zebra mussel infestations 16 – 19 . These ex situ management efforts are powerful tools used to maintain or increase biodiversity, but may also cause stress for the animals, making them more vulnerable to factors that directly contribute to translocation failure, such as starvation, disease, and reduced reproductive capacity 20 .…”