Effects of capture by trammel net on Colorado River native fishes

Journal of Fish and Wildlife Management
By: , and 



Trammel nets are commonly used to sample rare fishes; however, little research has assessed delayed mortality associated with this capture technique. We conducted laboratory experiments to evaluate the effects of capture by trammel net on bonytail Gila elegans, razorback sucker Xyrauchen texanus, and roundtail chub Gila robusta, at 15, 20, and 25uC. Fish (139–288 mm total length) were entangled in a trammel net for 2 h or captured by seine net and then monitored for mortality for at least 14 d. Blood samples were collected immediately after capture, and plasma cortisol levels were quantified as an index of capture-related stress. The cortisol response varied by species, but mean cortisol levels were higher for fish captured by trammel netting (295.9 ng/mL) relative to fish captured by seine netting (215.8 ng/mL). Only one fish (of 550) died during capture and handling, but 42% of the trammel-netted fish and 11% of the seine-netted fish died within 14 d after capture. In general, mortality after capture by trammel net increased with increased water temperature and at 25uC was 88% for bonytail, 94% for razorback sucker, and 25% for roundtail chub. Delayed mortality of wild-caught fish captured by trammel net has the potential to be high, at least under some circumstances. We suggest that sampling frequency, timing of sampling (relative to reproductive cycles), and water temperature all be considered carefully when using trammel nets to sample diminished populations of imperiled native fishes.
Publication type Article
Publication Subtype Journal Article
Title Effects of capture by trammel net on Colorado River native fishes
Series title Journal of Fish and Wildlife Management
DOI 10.3996/122011-JFWM-070
Volume 3
Issue 1
Year Published 2012
Language English
Publisher U.S. Fish and Wildlife Service
Publisher location Arlington, VA
Contributing office(s) Southwest Biological Science Center
Description 9 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Journal of Fish and Wildlife Management
First page 133
Last page 141
Country United States
Other Geospatial Colorado River
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