Laserfiche WebLink
<br />(;"Z~--'7 <br />'J ~..:.. <br /> <br />control strategies, especially for those strategies that required a large investment of <br />labor. <br /> <br />Virtually all of the scenarios focus control efforts on nonnatives that have been <br />identified as predators. This is not surprising, due to significant problems that have <br />been reported for some of the fishes. Of all the predators discussed, the channel <br />catfish was mentioned most frequently in the scenarios. Common carp and several <br />centrarchids were also mentioned frequently, perhaps due to the possibility for using <br />the same control method for all three of these species. <br /> <br />Most participants were concerned with predation of nonnative fishes on larval <br />and juvenile life stages of the listed fishes and many of the scenarios directed effort at <br />reducing the abundance of predators in the channel or in nursery areas. Other <br />scenarios were directed at controlling the input of nonnative fishes from lentic habitats <br />(e.g., floodplain ponds and reservoirs) or from stocking. <br /> <br />The recommended control measures were a diverse mix of techniques and <br />methods that have been recommended in the past. The most commonly mentioned <br />method was mechanical removal by use of traps. The most unusual technique involved <br />establishment of a commercial fishery for channel catfish and common carp. Other <br />methods involved policy changes that would govern stocking, or set fishing regulations <br />to assist in removal of nonnative fishes. Flow management for nonnatives is already <br />part of the Program and presumably will be implemented as part of a program that <br />improves habitat for the native fishes as well. Some techniques were intended to <br />prevent or reduce the movement of nonnatives into the mainstream river, and included <br />pond reclamation (chemical fish removal), escapement control, and nursery protection. <br /> <br />The beneficiary native species was not always specified in the scenarios (Table <br />10). Nevertheless, it was clear from the workshop discussions that threats to the <br />Colorado squawfish and razorback sucker were very similar (Table 6). There was less <br />certainty about interrelationships between non natives and the humpback chub, due to a <br />general lack of information about the humpback chub in the UCRB. <br /> <br />Workshop discussions also included the need for pursuing some control actions <br />in a particular sequence. For example, northern pike now exist in the Gunnison River <br />because of escapement from Paonia Reservoir. There are plans to improve floodplain <br />and backwater habitats in this area to benefit native species. However, these <br />improvements also could harbor nonnative species such as northern pike. It would be <br />prudent to remove the pike from the system before preceding with the habitat <br />improvements. <br /> <br />The scenarios developed by workshop participants represented a range of <br />possibilities, but should not be taken as an exhaustive list. A limited amount of time <br /> <br />32 <br />