Ecology of bonytail and razorback sucker and the role of off-channel habitats in their recovery

Survival and growth rates of stocked razorback suckers (Xyrauchen texanus) in a wetland of the Green River, Utah

“…The faster growth rate in Baeser Bend was possibly the result of fewer nonnative fish and maintenance of fresh water by pumping river water into the wetland during the summer. Mueller (2006) reported young razorback suckers growing 0.2 mm/d in Cibola High Levee Pond, where dietary competition among small fish may have been a limiting factor.…”

“…It has been successful when razorback suckers are raised in offchannel habitats in the lower Colorado River Basin and is a strategy for razorback sucker recovery (Mueller, 2006). However, wild-produced larval razorback suckers face the challenge of entering natural floodplain wetlands because spring flows are often too low to connect mainchannel habitat with floodplain wetlands or are ill-timed (i.e., floods subside before larvae appear).…”

“…Floodplain wetlands are thought to have great value as nursery habitat for razorback suckers because they have lower water velocity, warmer temperatures, and richer food production than do main channel habitats (Modde, 1996;Modde et al, 2001;Mueller, 2006). It has been successful when razorback suckers are raised in offchannel habitats in the lower Colorado River Basin and is a strategy for razorback sucker recovery (Mueller, 2006).…”

“…However, wild-produced larval razorback suckers face the challenge of entering natural floodplain wetlands because spring flows are often too low to connect mainchannel habitat with floodplain wetlands or are ill-timed (i.e., floods subside before larvae appear). Even if they do enter, they are often eaten by the many nonnative fish predators in the wetland (Modde et al, 2001;Mueller, 2006). If larval razorback suckers can enter the wetland and avoid predation, their probability of survival increases.…”

“…However, when nonnative fish invaded and spawned, razorback sucker larvae were no longer observed. Nonnative fish predation appeared to be the primary factor limiting razorback sucker recruitment (Mueller, 2006). In Upper Klamath Lake, Oregon, Markle and Dunsmoor (2007) found a negative relationship between abundance of fathead minnows and survival of larval shortnose suckers (Chasmistes brevirostris) and Lost River suckers and noted predation on larval suckers by fathead minnows.…”