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    Author(s): R.A. Knapp; K.R. Matthews
    Date: 2000
    Source: Conservation Biology 14:428-438
    Publication Series: Miscellaneous Publication
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    Abstract: One of the most puzzling aspects of the worldwide decline of amphibians is their disappearance from within protected areas. Because these areas are ostensibly undisturbed, habitat alterations are generally perceived as unlikely causes. The introduction of non-native fishes into protected areas, however, is a common practice throughout the world and may exert an important influence on amphibian distributions. We quantified the role of introduced fishes (several species of trout) in the decline of the mountain yellow-legged-frog (Rana muscosa) in California’s Sierra Nevada through surveys of >1700 sites in two adjacent and historically fishless protected areas that differed primarily in the distribution of introduced fish. Negat ive effects of fishes on the distri bution of frogs we re evident at three spatial scales. At the l a n d s c ape scale, c o m p a risons between The two protected areas indicated that fish distri bution was stro n g ly n egat ive ly corre l at e d with the distribution of frogs. At the watershed scale, the percentage of total water-body surface area occupied by fishes was a highly significant predictor of the percentage of total water-body surface area occupied by frogs. At the scale (if individual water bodies, frogs were three times more likely to be found and six times more abundant in fishless than in fish-containing water bodies, after habitat effects were accounted for. The strong effect of introduced fishes on mountain yellow-legged frogs appears to result from the unique life history of this amphibian which frequently restricts larvae to deeper water bodies, the same habitats into which fishes have most frequently been introduced. Because fish populations in at least some Sierra Nevada lakes can be removed with minimal effort, our results suggest that the decline of the mountain yellow-legged frog might be relatively easy to reverse.

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    Knapp, R.A. and K.R. Matthews. 2000. Non-native fish introductions and the decline of the mountain yellow-legged frog from within protected areas. Conservation Biology 14:428-438


    yellow-legged frog

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