Influence of Raceway Substrate and Design on Fin Erosion and Hatchery Performance of Rainbow Trout
R.E. Arndt, M.D. Routledge, E.J. Wagner,
R.F. Mellenthin-2001
North American Journal of Aquaculture, 63(4): 312-320
Abstract:
Raceway substrate and design were manipulated in a
series of four trials to improve fin condition of rainbow trout Oncorhynchus
mykiss. In the first trial, fish were reared in either conventional
concrete raceways or raceways fitted with a false floor overlaid with cobble
and through which water and waste materials flowed. Growth, feed
conversions, and mortalities were not influenced by treatment type, but fish
reared in false-floor raceways exhibited an improvement in fin lengths. For
trial 2, fish were raised in control raceways or raceways that contained
two-dimensional, painted gravel patterns (2D) as a substrate or actual
gravel affixed to the raceway bottom (3D) to provide a three-dimensional
appearance. Growth, feed conversions, and mortalities were not influenced by
treatment type, but fish in the 3D treatment had significantly better dorsal
fins compared with the control and 2D groups. Anal fins, pelvic fins, and
right pectoral fins were significantly better for control and 3D fish
compared with 2D fish. For trial 3, fish were reared in either control
raceways or raceways with walls and bottoms that had been smoothed by the
application of a resin. Fish performance was not affected by raceway
coating; however, fish reared in the coated raceways had significantly more
fin erosion than control fish over the course of the study, although by the
end of the study these effects appear to have been transient. In trial 4,
treatment raceways fitted with a cross-flow system, either with gravel
substrate panels or without, were compared with plug-flow controls. At the
end of the study, fish reared in the raceways with gravel had better final
weights, growth rates, and feed conversions compared with fish in the
plug-flow controls. Fins were generally significantly better for the fish in
both cross-flow raceways compared with the controls. The results indicate
that raceway substrate and design can be manipulated to reduce fin erosion
when culturing rainbow trout.
(Utah Division of Wildlife Resources, Fisheries
Experiment Station, 1465 West 200 North, Logan, Utah 84321, USA)