The Ecological Consequences of Exotic Fish in Florida Waters

Defense Date


Document Type


Degree Name

M.S. Marine Biology

First Advisor

Richard E. Dodge

Second Advisor

Curtis Burney


This paper examines the ecological consequences of exotic fish, species that were most probably brought into this country by man. The term "exotic" in this paper is meant to denote a species from another continent. This "nonnative" species is not fully acclimatized to the environment that it now inhabits. A "transplanted" species is one that has undergone a range extension through natural or artificial means (i.e., the armadillo walked in from Mexico under its own power).

There is a clear mandate to maintain the biological integrity of this nation's waters (Federal Pollution Control Act of 1972). Exotic fish pose a distinct ecological disruption to the overall biotic structure in water bodies they inhabit. Most biologists and ecologists recognize the potentially disastrous effects of introducing species outside of their native range. These are very important biological concerns. Characteristics exhibited by the exotics can have harmful effects on the life histories and overall population size of the native sport fishes such as the largemouth bass, Micropterus salmoides floridanus. Unfortunately, once exotic fish become established into new territories, it is usually impossible logistically or impractical economically to eradicate them. Exotic fish become, for better or for worse, permanent additions to the fauna.

The importation of exotic fish into North America began in the late 1600's with the arrival of the ornamental goldfish. Since that time, concern over the purposeful introduction of exotic species relate primarily to the degree in which exotics become established (i.e., actively breeding and expanding) and compete with the native fish populations (termed indigenous or native species). The importation of exotic fish by various governmental agencies and private groups for purposes of aquaculture, sportfishing, or aquaria has led directly to the release or escape of many imported fish into Florida's waterways.

The intent of this paper is to focus on: (1) exotic fish alter the natural energy flow throughout native aquatic communities; (2) exotic fish are unpredictable outside their native range and their behavior (i.e., reproduction, feeding habitats, and predation) may bring about serious problems to the native fish assemblages; and (3) exotic fish can be a carrier of unknown pathogenic organisms.

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