Age and growth rates of the critically endangered fish Garra ghorensis can inform their conservation management

Authors

  • Nashat Hamidan,

    Corresponding author
    1. Royal Society for the Conservation of Nature, Amman, Jordan
    2. Centre for Conservation Ecology and Environmental Science, Bournemouth University, Poole, UK
    • Correspondence to: Nashat Hamidan, Royal Society for the Conservation of Nature, P.O. Box 1215, Amman, Jordan 11941. Email: nashat.hamidan@gmail.com

    Search for more papers by this author
  • J. Robert Britton

    1. Centre for Conservation Ecology and Environmental Science, Bournemouth University, Poole, UK
    Search for more papers by this author

Abstract

  1. Information on the life-history traits of threatened fishes can inform their conservation as they can indicate resilience to environmental change and vulnerability to extirpation and extinction. Garra ghorensis, a small (< 140 mm total length) riverine cyprinid fish, endemic to the southern Dead Sea area, is critically endangered through habitat loss and invasive species. There are, however, no data currently available on their life-history traits to inform their conservation management.
  2. The age structure and growth rate characteristics of three G. ghorensis populations in Jordan were assessed. Close to the sampling sites, minimum air temperatures approached 0 °C in January but maxima exceeded 40 °C in July and August. Samples collected monthly throughout 2011 contained fish with lengths between 23 and 137 mm, with most less than 100 mm. Monthly length distributions showed three distinct length modes in each population whose mean lengths increased throughout the warmer months.
  3. Growth check formation on scales was annual and their ageing revealed fish in each population present to at least 4 years old, with a maximum of 6 years. Comparison of these data with the length modes indicated that the modes corresponded to ages 0+, 1+ and >2 years. Variability in length at age was apparent within sites, suggesting protracted spawning. Females were significantly larger than males.
  4. Growth rates and lifespans of G. ghorensis were highest at the most disturbed site (habitat loss and the presence of the invasive Oreochromis aureus). This growth plasticity in response to slower flows and deeper water suggests G. ghorensis has some resilience to environmental disturbances and suggests that their conservation management might not have to return their habitats to pristine conditions to avoid impacts on their lifespan and growth parameters. It also shows that further work is needed to identify the issues that are affecting the persistence of their populations.

Copyright © 2014 John Wiley & Sons, Ltd.

Ancillary