Conserving Peripheral Trout Populations: The Values and Risks of Life on the Edge

Abstract

Peripheral populations-generally defined as those at the geographic edge of the range-often have increased conservation value due to their potential to maximize within-species biodiversity, retain important evolutionary legacies, and provide the fodder for future adaptation. However, there has been little exploration of their conservation value in aquatic systems. Inland cutthroat trout (Oncorhynchus clarkii) subspecies provide a unique opportunity to evaluate the distribution of peripheral populations and patterns of persistence across a wide range of environmental conditions. Our assessment analyzed range-wide losses of peripheral and core populations since the 1800s, and evaluated the likelihood of persistence for remaining populations of five cutthroat trout subspecies: Bonneville, Colorado River, Yellowstone, Rio Grande, and westslope. For all five, we found that core and peripheral populations have declined substantially, but the amounts of habitat occupied by peripheral populations generally have declined at a greater magnitude. The more isolated peripheral populations typically exhibited the greatest declines. Remaining peripheral populations often failed to meet minimum persistence criteria. Our characterization of peripheral populations and their losses emphasizes the need for closer evaluation of conservation priorities and management actions for cutthroat trout and other fishes if the values of peripheral populations are to be maintained.

Effects of Temperature and Spatial Scale on Rio Grande Cutthroat Trout Growth and Abundance

“…Climate effects are expected to be especially concerning in the southwestern USA, where reduced flow and increasing temperatures are anticipated to further constrain trout distributions, particularly along the southern periphery (Haak et al. ; Wenger et al. ).…”

An Evaluation of Mississippi Barrier Islands as a Spawning and Nesting Habitat for the American Horseshoe Crab, Limulus polyphemus, with Implications for Island Restoration

“…This is evident in both the timing (Penn andBrockmann 1994, Sekiguchi and) and the location (Badgerow and Sydlik 1989, Penn and Brockmann 1994, Brockmann 2003) of spawning activity, as well as the dominant behavioral cues (Rudloe 1985, Barlow et al 1986, Brockmann 2003, Ehlinger et al 2003. Typically this type of plasticity is highly localized and more pronounced at the extreme edges of a species' distribution (Fraser 1999, Haak et al 2010, so in examining HSC spawning patterns on Mississippi barrier islands we expected to find some differences, particularly in comparison to well studied populations along the U.S. Atlantic coast and in Florida.…”

Annual Variation of Spawning Cutthroat Trout in a Small Western USA Stream: A Case Study with Implications for the Conservation of Potamodromous Trout Life History Diversity

“…For many potamodromous trout populations, knowledge of the diversity of life history patterns, including spawning ecology (e.g., Northcote and Lobon-Cervia 2008), is remarkably limited but not surprising given the challenges of sampling and monitoring potamodromous trout populations in headwater streams. However, identifying the within-and across-population diversity is critical for setting conservation targets to enhance species persistence (Haak et al 2010;Schindler et al 2010).…”

“…Furthermore, we consider our results to be a case study in identifying the diversity of life history patterns of Cutthroat Trout in headwater streams; understanding the diversity of such patterns can be used in directing local management actions (e.g., timing and intensity of livestock grazing; Peterson et al 2010) as well as devising population and species conservation frameworks (Haak et al 2010). This study is one of the first to investigate the spawning activity of stream-dwelling Bonneville Cutthroat Trout over several spawning seasons.…”