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<br />Aquatic Sciences
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<br />beyond the native riverine distribution of the species, some
<br />interest was shown in the U.S. to introduce that fish. Nik
<br />perch are the largest of the snooks (Centropomidael. growing
<br />to a weight of more than 160 kg. In 197 [, the American
<br />Fisheries Sociely Exotic Fishes Committee prepared a repOti
<br />on Nile perch, emphasizing that its low thermal tolerance made
<br />it unsuitable for introduction in most U. S. waters and rec-
<br />ommended against its introduction.7K Introduction of this large
<br />predator into Lake Victoria and certain other African lakes was
<br />disastrous for native fishes and to fishery economics of affected
<br />countries.7') Its proposed introduction to Australia was termi-
<br />nated due to its potential to severely impact native barramundi
<br />perch (L. calcarifer) and other native fishes.7~
<br />Apparently the idea of exotic, giant snook in heated power
<br />plant reservoirs was attractive to Texas. In the 1970s, the Texas
<br />Department of Parks and Wildlife proposed introduction of
<br />Nile perch. [n this instance, they followed. in pan, the early
<br />steps of the 1972 American Fisheries Society policy statement
<br />on introductions of exotic fishes. A team of biologists was
<br />sent, on several occasions, to East Africa, to study Nile perch
<br />and three other candidate species of Lales in their native bio-
<br />tope. Those biologisls decideo against introduction of Nile
<br />perch, but recommended the bigeye lales (L. /lwriue), the
<br />smallest of the African centropomids under consideration, for
<br />release into heated reservoirs for further stuoy. Three species.
<br />the Tanganyika lates (L. angustifrons), bigeye lates, ano Nile
<br />perch were transported to Texas for studies in closed systems
<br />and as brood stock.-'6
<br />Giant snook were too tempting, ano Nile perch were intro-
<br />duced into Victor Braunig Reservoir, Bexar County, Texas in
<br />1979. Only males were introduced, but sex reversal is known
<br />in centropomids.Ko The fish failed to survive. Later, in 1983,
<br />the Texas Department of Parks and Wildlife stocked higeye
<br />!ates, as recommended by the team they had sent to Africa.
<br />Bigeye lates were introduced into several reservoirs, including
<br />one on the coast, with the stated purpose being reduction of
<br />previously introduced and established tilapiasv, The snook
<br />failed to survive, partly due to inaoequate forage, except in
<br />the coastal reservoir, ~(, and mostly because of cold tempera-
<br />tures.",.KI Prior to 1986, Texas had not abanooned the hope of
<br />establishing exotic snooks in !ts reservoirs;K' recently, how-
<br />ever, policy has changed and introductions of nonnative fishes
<br />are discouraged. Texas has tried nearly every exotic fish pro-
<br />posed for introduction into U.S. waters to date, made many
<br />transplants from beyond ils borders, and exceeded other states
<br />with the introduction of marine fishes into inlanu waters. [t
<br />appears that the no management policy that dominated intro-
<br />ductions in Texas for so long has been changed to a no intro-
<br />(dllcliOIl policy. OIL kasl for the pn:scllt. Wherc rcspollsihk ~
<br />ma~lagemen~ ba~ed on sounu,biological investigations oemanos
<br />an Il1troductlon 111 the face of no alternative, then and only then
<br />should an introduction be seriously considered.
<br />
<br />VIH. PIQUED BY Pl;{E
<br />
<br />Successful establi.shment of striped bass aloq; p;HiS of t>._~
<br />U.S. Pacific coast during the latter part of the lB\)Os ;lnd i\s
<br />expanding introduction into U.S. inland \';;\ters piqued i'llcrc:;[
<br />in the Soviet Union during the 1960s to introduce tllis specics
<br />to its waters. A request to the U.S. from Russia for st;-ip:,l
<br />bass was made. Pennsylvania requested Amur pike (E. !'t'!ch.
<br />erti) in return.
<br />Lachner et al.,-' in discllssing the Amur pik.e, C();]C!t:C::d
<br />".. .that the ecological niche suitable for the Ainur pikl: can
<br />be occupied by one or two native esocids." Coupcr'c reco;-ded
<br />the introduction, noting that it has "added diversity to recre-
<br />ational angling" and that "severe acid-ll1i;~e drall~;tgc to thi;
<br />outlet stream is thought to be an adequate barrier \0 (hpcr:;;;l
<br />of this exotic from its planting site" (Gkildale Lake, a In;,r;-
<br />made reservoir). Yet, in 1972, flooding following! [uni;';';;,!
<br />Agnes resulted in escape of brood fish 1':\'111 the: h;,tc"h,','", .,
<br />Although there is no evidence ofreprOl!uclIC:l outside of l~kn-
<br />dale Lake, the idea that fishes can be ]OC;\'ly ., j,-"'uu;xcl ;;;~(
<br />effectively kept III pace laS again bCCill1"<)\',-d j1<ll\e. ;\itr:C\I~:;'
<br />no one has said so in print, we have been l;lld nil m;::,,, ,)':-
<br />casions that a motivating factor for selecting the J\!1il~r pd;c'
<br />was the fact that it was the only esoc1,] th;ll did nGt D'::C\i]" in
<br />Pennsylvania. This is reminiscent of the case of' the st;;;-;;,,::
<br />(SllImus \'ulgaris). introduced into North America i" ;:r. ::~::::
<br />effort to establish all birds mentioned in the y:rilings GfV/I]i;;:-,
<br />Shakespeare. X3
<br />The Amur pike is a sister species of the hoLu'Ctic IWilhe:m
<br />pike (E. lueius), restricted to the Al11ur bacin or iWl';;C;i::i:,;
<br />Asi.a. The genetic distance between the t\\'o ~pl:('ics is un1;:-;(\\'.;;,
<br />but COUl1enay and Kohler" noted that PCl1nsylviW::1 Vi,:; ci'i-
<br />luring hybrids between them. Introgressive hy~'ridiz;ltions;s
<br />already shown for native F..wx by Raney'" in !\i,,~:.;aL'hu\c'ii,':_
<br />The possibility exists for changing, thl'Llugh hybliulJ:atil)il, ':,:
<br />genetic makeup of northern pike populations in Pennsyhani;\
<br />and perhaps in adjoining jurisdictions. Much has been "lid
<br />about use of strains of vilrious organisms produced "ilh re-
<br />combinant DNA in agriculture and medicine. Yet fiSher:'-'.")'
<br />scientists Illay unwillingly be shifting ge:netic composition
<br />through introgression by introducing species il,1t(,) ecosYSL;nl,:';
<br />occupied by closely allied species, or by inll(),i;lcing hyhrid
<br />stocks, the result of the most primitive form of gene splicing.
<br />into waters where one of the parental types is native.
<br />
<br />IX. STRANGERS IN THE SEA
<br />
<br />The introduction of marine fishes from ol1e place to lln'lthcr
<br />ill OCI:,1I1ic wilters WilS 11IOSt recently reviewed by Maciolek. Ii
<br />Carlton,K' ano Randall.~" lIawaii is the only area where 1l1,Irille
<br />fishes have been successfully inlrodueed, but the Mozambique
<br />tilapia, not a marine species, though euryhalinc, is established
<br />
<br />1989
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<br />167
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