Physiological Responses of Adult Rainbow Trout Experimentally Released through a Unique Fish Conveyance Device

Abstract

We assessed the physiological stress responses (i.e., plasma levels of cortisol, glucose, and lactate) of adult Rainbow Trout Oncorhynchus mykiss at selected time intervals after they had passed a distance of 15 m through a unique fish conveyance device (treatment fish) or not (controls). This device differs from traditional fish pumps in two important ways: (1) it transports objects in air, rather than pumping them from and with water; and (2) it uses a unique tube for transport that has a series of soft, deformable baffles spaced evenly apart and situated perpendicular within a rigid, but flexible outer shell. Mean concentrations of the plasma constituents never differed (P > 0.05) between control and treatment fish at 0, 1, 4, 8, or 24 h after passage, and only minor differences were apparent between the different time intervals within a group. We observed no obvious injuries on any of our fish. Our results indicate that passage through this device did not severely stress or injure fish and it may allow for the rapid and safe movement of fish at hatcheries, sorting or handling facilities, or passage obstacles.

Received March 5, 2013; accepted August 5, 2013

ACKNOWLEDGMENTS

This study was supported by funding from the U.S. Geological Survey. We thank Vincent Bryan III, Todd Deligan, Tony Finazzo, and Jeff Gueble of Whooshh Innovations for their technical assistance. We also thank Joe Benjamin, Alec Maule, Dennis Sitherwood, Lyman Thorsteinson, Joe Warren, and Steve Waste for technical and administrative assistance. Reference to trade names does not imply endorsement by the U.S. Government.