|
<br />
<br />eng a Bala'nce: '.',', ,,' '.' ,,' ,
<br />
<br />between non-native and endangered fish in the upper Colorado River basin
<br />
<br />D' uring the past 100 years in
<br />North America, 40 species
<br />, " ' and subspecies of fish have
<br />gone extinct; another 364 fish species
<br />are threatened with extinction. Biolo-,
<br />gists believe the priniary causes are"
<br />habitat changes, such as construCtion
<br />of dams and introductions of non'na~
<br />tive fish.
<br />Only 14 fish speCies are native to the
<br />upper Colorado River Basin; eight of
<br />these ate either listed as endangered or
<br />are candidates for listing. More than
<br />40 non-native' fish species have been,
<br />introduced ,- many adversely affect na~
<br />, tive Colorado River'fish. For'example:
<br />, ~ Studies onUtah's Duchesne River
<br />foUnd that i- to 3-year-oldCol'
<br />orado, squaw-fish constituted, 5 '
<br />percent of the diets of northern '
<br />pike, even, though squawfish
<br />,made up a small portion of the '
<br />available food. A single northern
<br />pike can consume more thari 100
<br />
<br />...
<br />
<br />and as much as 20 times the num-
<br />ber of squawfish as green Sunfish.
<br />Young Colorado squaw fish have
<br />been found in the stomachs of
<br />'channel catfish collected in the
<br />Dolores River, ~ven though'
<br />squawfish are very rare in this
<br />river. Also, research showed a
<br />,handful of squawfish died tiying
<br />to, eat channel catfish whose
<br />spines became lodged' in their
<br />'mouthS. '
<br />
<br />Recovery Program Involvement
<br />Controlling the, adverse effects, of
<br />non'native fishes on endangered fishes
<br />is on of five rnajorelements ofthe Re-
<br />covery Program: '
<br />The, Program recommends that sto- '
<br />cking of 'non-native species be, con-
<br />fined to areas where an absence of con-
<br />flict with protected -fish can be demon-
<br />strated. It also calls for the Service and
<br />states to develop procedures ,for resolv-
<br />.. - , 'ing disagreements
<br />" ~ ;~~ of fish-stockiitg re-
<br />"y ';,::, commendattons'. '
<br />...,.~ -
<br />
<br />
<br />dam and in certain standing wa-
<br />ters separated from rivers occu-
<br />pied by endangered 'fish.
<br />... Black crappie, bluegill, channel
<br />,catfish and largemouth bass can
<br />, be stocked without review in cer-
<br />tain standing waters or isolated
<br />, ponds and reservoITs.
<br />... Proposals to stOCK walleyes, yel-
<br />,low perch, wipers or tiger muskies
<br />will be reviewed' case-by-case ac-
<br />cording to stocking location, po-
<br />tential for the fish to escape into
<br />endangered-fish, habitats, mea-
<br />sures that could offset hann to en-
<br />dangered fish and other criteria.
<br />... In Colorado, ongoing stocking of
<br />non-native fish, aS,allowed in ex-
<br />isting lake-management plans,
<br />can prciceed'Ni1;hout review. This
<br />is the case for the following lakes
<br />, . and reseivoirs: Rio Blanco, Hal-
<br />lenbeck, Mack Mesa, Chip eta
<br />Lakes, Crawford, Narraguiimep,
<br />Puett, Summit and'Totten.
<br />... In stretches of river currently oc-
<br />cupied by endangered fish, stock-
<br />'ing ,of non-native fish species
<br />other thari trout is prohibited.
<br />
<br />Non-native fish stri'
<br />, eking procedures
<br />To' address the Issues regarding specifienon-native
<br />sometimes compet- fish species '
<br />, ing goals of recov- , ' ' Tiger muskies in Harvey Gap Reser-
<br />e'ring' endangered voir-- The Colorado Division of
<br />fish and ,stockingWlIdlife haS projiosed Stocking tiger
<br />: game fish, the Ser- inwikies in Harvey Gap" an 'isolated
<br />vice ,and states of reservoir near Rifle.' However, biolo-
<br />Colorado, Utah and gists believe muskies could have a sig-
<br />Pholo "" Pony, Conway Wyoming develop- nificant negative impact ifthey were to
<br />More than 40 non-native fish species have been introdue8d ed interim proce- come in'contact with native and endan-
<br />_ many adversely affect native Colorado River fish. dures for stocking gered fishes in the Colorado River
<br />, , " , _ ' non-native fish ill Basin.' The Fish and Wildlife Service
<br />, squawfish per year. ' the upper Colorado River Basin to en- and others will be reviewing the Divi-
<br />~ At least four studies have shown 'sure that stocking of non-natives is sion's proposal over the next 60 days.
<br />predation by channel, catfish, compatible with recovery, of endan- Contr%f northern pike --The Ser-
<br />green sunfish and carp on razor- geied'fishes, Highlights include: vice and'the Division of WlIdlife are
<br />back sucker eggs and larvae. ... Trout species can be stocked with- working together to remove northern
<br />... StUdies of predation on Colorado out'review anywhere in the upper pike from the Gunnison R'iver. A sim-
<br />squawfish and various non-native Colorado River Basin, even ilar effort planned for the Yampa River
<br />fish, showed that largemouth bass though there may be minor ad-' has been postponed for a year pending
<br />exhibit a strong preference for na- verse impacts on endangered fISh. more public, involvement and comple-
<br />tive fish, eating twice as many ... Smallmouth bass can be stocked tion of a strategic plan for non-native
<br />young squawfish as red shiners without review upstream of the fish c'ontrol. _
<br />
<br />6
<br />
|