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Comparison of visual survey and seining methods for estimating abundance of an endangered, benthic stream fish

Environmental Biology of Fishes

By:
, , ,
DOI: 10.1007/s10641-007-9202-0

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Abstract

We compared visual survey and seining methods for estimating abundance of endangered Okaloosa darters, Etheostoma okaloosae, in 12 replicate stream reaches during August 2001. For each 20-m stream reach, two divers systematically located and marked the position of darters and then a second crew of three to five people came through with a small-mesh seine and exhaustively sampled the same area. Visual surveys required little extra time to complete. Visual counts (24.2 ?? 12.0; mean ?? one SD) considerably exceeded seine captures (7.4 ?? 4.8), and counts from the two methods were uncorrelated. Visual surveys, but not seines, detected the presence of Okaloosa darters at one site with low population densities. In 2003, we performed a depletion removal study in 10 replicate stream reaches to assess the accuracy of the visual survey method. Visual surveys detected 59% of Okaloosa darters present, and visual counts and removal estimates were positively correlated. Taken together, our comparisons indicate that visual surveys more accurately and precisely estimate abundance of Okaloosa darters than seining and more reliably detect presence at low population densities. We recommend evaluation of visual survey methods when designing programs to monitor abundance of benthic fishes in clear streams, especially for threatened and endangered species that may be sensitive to handling and habitat disturbance. ?? 2007 Springer Science+Business Media, Inc.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Comparison of visual survey and seining methods for estimating abundance of an endangered, benthic stream fish
Series title:
Environmental Biology of Fishes
DOI:
10.1007/s10641-007-9202-0
Volume
81
Issue:
3
Year Published:
2008
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Environmental Biology of Fishes
First page:
313
Last page:
319
Number of Pages:
7