An Individual-Based Model for Population Viability Analysis of Humpback Chub in Grand Canyon

Authored by III William E Pine, Brian Healy, Emily Omana Smith, Melissa Trammell, Dave Speas, Rich Valdez, Mike Yard, Carl Walters, Rob Ahrens, Randy Vanhaverbeke, Dennis Stone, Wade Wilson

Date Published: 2013

DOI: 10.1080/02755947.2013.788587

Sponsors: United States Geological Survey (USGS)

Platforms: No platforms listed

Model Documentation: Other Narrative Mathematical description

Model Code URLs: Model code not found

Abstract

We developed an individual-based population viability analysis model (females only) for evaluating risk to populations from catastrophic events or conservation and research actions. This model tracks attributes (size, weight, viability, etc.) for individual fish through time and then compiles this information to assess the extinction risk of the population across large numbers of simulation trials. Using a case history for the Little Colorado River population of Humpback Chub Gila cypha in Grand Canyon, Arizona, we assessed extinction risk and resiliency to a catastrophic event for this population and then assessed a series of conservation actions related to removing specific numbers of Humpback Chub at different sizes for conservation purposes, such as translocating individuals to establish other spawning populations or hatchery refuge development. Our results suggested that the Little Colorado River population is generally resilient to a single catastrophic event and also to removals of larvae and juveniles for conservation purposes, including translocations to establish new populations. Our results also suggested that translocation success is dependent on similar survival rates in receiving and donor streams and low emigration rates from recipient streams. In addition, translocating either large numbers of larvae or small numbers of large juveniles has generally an equal likelihood of successful population establishment at similar extinction risk levels to the Little Colorado River donor population. Our model created a transparent platform to consider extinction risk to populations from catastrophe or conservation actions and should prove useful to managers assessing these risks for endangered species such as Humpback Chub. Received August 28, 2012; accepted March 13, 2013

Tags

Management ecology Temperature Life-history Arizona Colorado river Native fishes Gila-cypha Turbidity Capture