Publication Date

8-2013

Type of Culminating Activity

Thesis

Degree Title

Master of Science in Biology

Department

Biology

Supervisory Committee Chair

Peter Koetsier, PhD.

Abstract

Invasive fish species have been identified as a major threat to aquatic biodiversity world-wide. The most successful of these invaders share several life history characteristics such as long lifespan, high fecundity, multiple reproductive events, generalized omnivorous diet, and tolerance for a wide range of environmental conditions. Although many studies have focused on well-known and economically costly invaders, there are many invasive fish about which very little is known. In this series of studies, I describe some life history characteristics of one such invasive fish, the oriental weatherfish (Misgurnus anguillicaudatus). I collected 586 specimens from water bodies connected with the lower Boise River, Idaho, USA. For the first study, I dissected 237 of these individuals and used morphometrics, ova counts, and otolith ageing to build a life history profile of this invasive population. I found a 1:1 sex ratio of sexually mature males and females. Young of the year displayed rapid growth to sexual maturity within one year of life and fish lived to six years of age in the wild. Upon reaching maturity, the fish became capable of reproduction during two predicted spawning events over a protracted spawning season (June through October). Female fish had the capacity for releasing up to 40,000 eggs per spawning season. For the second study, I examined the stomach contents of the dissected fish and used gravimetric, frequency, and abundance data to determine the fish’s diet. Oriental weatherfish were eating a generalized diet of aquatic invertebrates and detritus. For the third study, I used a temporally extended Critical Thermal Minimum (CTmin) approach to find the lowest water temperature that the fish could survive. Fish survived exposure to subfreezing water temperatures and direct contact with ice. I used logistic regression to estimate the CTmin of this sample of oriental weatherfish as -1.76°C. This series of studies shows that the oriental weatherfish possesses many hallmark characteristics of other successful invasive fishes. These characteristics, coupled with ongoing dispersal through the aquarium pet trade make the oriental weatherfish an ideal invasive species. Currently, the oriental weatherfish is invasive in at least 10 countries throughout the world, and further research into the impacts that the fish has on native faunal communities is needed.

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