NORTH AMERICAN JOURNAL OF FISHERIES MANAGEMENT

Volum e9 Winter 1989 Numbe1 r

North American Journal of Fisheries Management 9:1-11, 1989

Proposed Biological Management of Mysis relicta in Colorado Lake Reservoird san s PATRICK J. MARTINEZ Colorado Division Wildlife,of 711 Independent Avenue Grand Junction. Colorado 81505, USA ERIC P. BERGERSEN U.S. Fish Wildlifeand Service, Colorado Cooperative Fish Wildlifeand Research Unit1 Room 201 Wagar Building, Colorado State University Fort Collins, Colorado 80523, USA

Abstract. —The opossum shrimp Mysis relicta bees ha n introduced into many lake reservoird san s outside its native range to supplement the prey bases for fish. Colorado has received more intro- ductions of the mysid than any other state or province in western North America, but not all of these introductions have been beneficia r innocuouso l . Mysid predatio zooplanktonn no , partic- ularly cladocerans resultes ,ha diminishedn i d foo somr dfo e fishes, especiall planktivorer yfo s such kokanee th s a e Oncorhynchus nerka smald an l trout Oncorhynchus sppfishew .Fe s e foragth n eo often abundant population introducef so d mysids. Management option limitee sar laken di s where M. relicta compete eliminateds forha r ,o large th , e zooplankters eate fishy nb . Furthermoree th , mysi shows dha n enough vagilit expano yt nonnativs dit hary e mrangma d fisherieean watern si s that it enters. Because its eradication is not now feasible, the development of strategies to control or benefit from established mysid populations is warranted. Biological controls appear most feasible. Amphipods and fishes that have the potential to control or benefit from nuisance mysids through competitio predatior no candidatee nar introductionr sfo 1e 3th specief O . s thaexaminede w t e ,th deepwater sculpin Myoxocephalus thompsoni was our first choice for introduction into waters containing established mysids basee .W d this choic potentias it n eo eitheo t l r control mysid numbers r channeo l mysid productio predatoro nt s wit hadverso n littl r o e e th e res effectf th o t n o s community.

As a result of widespread introductions intended received more introductions of this mysid than to supplement the prey base for fishes, the opos- any other state or province in western North sum shrimp Mysis relicta has become established America (Table 1). in many lake reservoird san s outsid s nativeit e Mysis relicta, considered a true glaciomarine rel- range in North America and northern Europe ict crustacean in its native range, has a circumpolar (Gosho 1975; Lasenb t alye . 1986). Colorad s distributiooha norte th hn ni hemisphere (Segerstrale 1962) Nortn I . h America nativs it , e distribution Continentae eass th i f to l Divid remnann ei t Pleis- ———— unie sponsores ti Th ' d U.S e byth . WildlifFisd han e tocene Proglacial lakes (Ricker 1959). Service Colorade th , o Divisio f Wildlife no e mysi Th Colod dan , -occur n deei s p oligotrophic lakes rado State University. having cold, well-oxygenated waters (less than 14°C 1 MARTINEZ AND BERGERSEN

TABLE 1.—Summary of Mysis relicta introductions in western North America as of 1987.

Lakes receiving M. relicta Established8 Passive Province Number trans- or state stocked Number port15 Total Reference Canada Alberta 4 3 0 3 DeHenau(198l) British Columbia 19 10 1 11 Lasenbyetal. (1986) United States California0 11 4 1 5 Gosho (1975); A. Cordone, California Department of Fish and Gamed Colorado 51 13 5 18 Finnell (1977); Nesler (1986) Idaho 16 3 0 3 Gosho (1975) . Mauser;G , Idaho Departmen Fisf Gamed o t han d Montana 8 5 1 6 W. Beatty, Montana Department of Fish, Wildlife, and Parksd Nevadac 4 0 0 0 Gosho (1975) . CoffinP ; , Nevada Departmen Wildlifef o t d Oregon 11 2 0 2 Gosho (1975); J. Griggs, Oregon Department of Fish and Wildlifed Utah 7 2 0 2 . JohnsonJ , Utah Departmen Wildliff o t e Resourcesd Washington 1 1 0 1 Gosho (1975) . Brown;L , Washington Departmen Gamef o t d Wyoming 2 2 0 2 J. Baughman, Wyoming Game and Fish Department4 Totals 134 45 8 53 waterl al t sa No receivin . relictagM introductions have been checke verifo dt speciese yth ' establishment. b Populations resulting from dispersal of mysids via downstream transport or water diversion. c Lake Tahoe, California-Nevada includes i , Californin di a information. d Personal communication.

with more dissolve g tham n2 d oxygen/L). During food source for predatory salmonids at the size at the day, it is typically found on the bottom in the which their principal diet changes from inverte- hypolimnion; at night, it makes extensive vertical brates to fish (Sparrow et al. 1964; Frantz and migrations that may be influenced by light inten- Cordone 1970)s . ha Muc A h US interes e th n i t sity, thermal stratification pred an ,y distribution been in enhancing growth of kokanee Oncorhyn- (Beeton and Bowers 1982). Mysis relicta is an op- chus nerka (Rieman and Falter 1981) as occurred portunistic omnivore that feed detritun so s (Las- afte . relicta rM establishe s wa Kootenan di y Lake, enby and Langford 1972), phytoplankton (Gross- British Columbia (Northcote 1972). nickle 1979), zooplankton (Coope Goldmad ran n mysil al t d No introductions have been beneficial 1980), amphipods (Parker 1980), possibly other or innocuous. An international group of research- mysids (DeGraeve and Reynolds 1975), dead an- ers recommended tha worldwida t e moratorium imals such as chironomids (Lasenby and Langford imposee b futurn do e introduction . relictaM f so 1973), and fish larvae (Cooper and Goldman 1980). (Morgan 1982) becaus threae th f eo t this crusta- Mysis relicta may reproduce seasonally (Furst cean poses to fisheries and their management. 1972b) or continuously throughout the year (Car- There are no known methods for eradicating my- penter etal. 19 74), at ages 1-4, dependin waten go r sids from lakes (Riema Falted nan r 1981; Lasenby temperature and lake productivity (Berrill and et al. 1986), so methods need to be devised to Lasenby 1983). It is extremely facultative in ex- minimize negative effect r derivo s e benefit from ploiting resource flourishind san g unde varietra y introduced populations. of ecological conditions. Pennak (1978) recommende . relictadM a s a Current Problems "logical" transplant becaus importancs it f eo n ei Cladoceran populations changed in many North diet lakf so e trout Salvelinus namaycush cord an - American and European waters after Mysis relicta egonines and because the "Mysis niche" was un- became established. Populations ofDaphnia spp. occupie mosn di t lakes. Furst (1972a) reasoned virtually disappeared in Lake Tahoe, California- that introductions of M. relicta and other glacial Nevada (Goldman et al. 1979), Lake Sturgusjoen, relicts among crustaceans would provid epatha - Norway (Langeland 1981), Donner and Fallen Leaf way between energy trapped in benthic detritus in lakes, California (Morgan et al. 1981), and Colo- profundae th l zon fishd ean . Others believed that rado's Grand Lake, Dillon Reservoir (Nelson the mysid would provide a larger, supplementary 1981), and Twin Lakes (LaBounty et al. 1980). BIOLOGICAL MANAGEMENT OF MYSIS RELJCTA

Seasonal abundance or species composition of WYOMING daphnia populations change Kootenan di y Lake, COLORADO British Columbia (Zyblut 1970), Lake Selbusjoen (Langeland 1981), Pend Oreille Lake, Idaho (Rie- man and Falter 1981), and Lake Granby, Colorado N (Martinez 1986). Mysids prey heavily on zoo- plankton t prefe,bu r daphnias (Coope Goldd ran - man 1980; Langeland 1981; Murtaugh 1981). Mysis relicta has indirectly influenced kokanee by depletin majos git r food supply (Wydoskd an i Bennett 1981). The mean size and numbers of 16 spawning kokanee decline Lakn di e Tahoe (Mor- kilometers ga alt ne . 1978), Lake Granby (Sealin Bennetd gan t 1980), and Pend Oreille Lake (Rieman and Falter FIGURE I .—Colorado lake reservoird san s with estab- 1981) afte mysie th r d became established. lished populations of Mysis relicta. Passive introductions Most fisheries in Colorado lakes having estab- e indicatear a singl y db e asterisr downstreafo ) k(* m lished mysid population e supportear s saly db - transport and by a double asterisk (**) for transmountain monids—rainbow trout Oncorhynchus mykiss water diversions (Finnell 1977; Nesler 1986): 1-Big Creek flower), 2—Carter**, 3—Chalk, 4—Chambers— ,5 (formerly Salmo gairdneri) and kokanee—that do Dillon, 6—Estes**, 7—Granby, 8—Grand, 9—Green occut no r naturall native th yn i e range of M. relicta Mountain, 10—Horsetooth, 11—Jefferson, 12—Marys**, and wer t exposeeno freshwateo dt r mysida s sa 13—Mount Elbert Forebay*, 14—Ruedi, 15—Shadow food source during their evolutionary history. Most Mountain*, 16—TaylorPark, 17—Turquoise, 18—Twin salmonids rarely encounter mysids during their (upper and lower). Heavy line through Colorado indi- active daytime feeding periods whe . relictanM s i cates the Continental Divide. in deep waters. Sight-dependent feeders such as trout and salmon typically do not feed extensively round. Management option reducee sar waterr dfo s when M. relicta is available to them during its in which large cladocerans have disappeared since nocturnal migration into surface waters. M. relicta became established. When the mysids are present on the bottom in In Colorado, M. relicta from Grand Lake (which shallow water, they appear abl evadeo t e predators is west of the Continental Divide) has become (Janssen 1978). In Colorado lakes where hypolim- establishe varioun di s water Contie s th eas f o t- netic dissolved oxygen is low before the fall and nental Divide (Figure 1). Nesler (1986) reported spring overturns sizel ,al mysidf so s appea- mi o rt that mysids were introduced into three foothills grate to shallower water. Although numerous po- lakes and reservoirs through passive transport via tential predators are present in these areas, their pumps, canals conduitd an , s (componente th f so stomachs contai mysidsw fe n . Stomachs often Colorado-Big Thompson transmountain water di- contain other benthic invertebrates such as iso- version and distribution project). Mysis relicta has pods Asellus sp., fingernail clams Pisidiwn sp.r ,o sprea othen di r systems (Furst 1981; Leathd ean chironomid larva pupad ean e (Martinez 1986). Graham 1982; Lasenby et al. 1986). This vagility Predatio mysidn no commos si n during periods may further increas lis e waterf eo th t s where eth of ice cover. In Colorado, lake trout, coho salmon specie less si s than desirable. Oncorhynchus kisutch, rainbow trout kokad an , - nee that were caught through the ice contained Control Alternatives large number mysidf Bennett. so L . s(G , Colorado sensitivite Th y of Mysis relicta elevateo t d tem- Division of Wildlife, personal communication). peratures (DeGraev Reynoldd ean s 1975) disw -,lo Low water temperature d subduean s d light solved oxygen (Sherman et al. 1987), increased throughout the water column in winter may induce nutrient loading (Colby et al. 1972), and pH change myside th enteo st r surface waters durin day,e gth (Nero and Schindler 1983) suggests certain phys- where they are vulnerable to predators. ical mean reducinf so eradicatinr go speciese gth . The limited use of mysids by fish in Colorado However, potential strategie effectinr sfo g physical lakes discourage e introductioth s . relictaM f no control, suc extrems ha e drawdown, therma- ma l elsewher statee th n ,ei particularl high-elevan yi - nipulations, or induction of hypoxia, eutrophica- tion, cold water impoundments wher woult ei - den tion acidificationr o , rarele ar , evef yi r applicable. zooplankton-producine th r te g surface waters year- Although several aquatic pesticide toxie sar o ct MARTINE BERGERSED ZAN N

crustaceans, none are known to be specific for M. to eat mysids on more than an occasional, inci- relicta. Both physical and chemical approaches in- dental, or seasonal basis. volve undesirable side effects suc jeopardizins ha g Other fish specie knowe sar consumo nt - emy or eliminating existing fisheries or reducing water sids, but they do not possess the behavioral or quality. ecological characters believed necessar providyo t e Introductions of biological control agents such reliable, persistent predatio mysidsn no . Splake as parasites or diseases have been suggested to (the hybrids between lake trout and brook trout control the mysid (Leathe 1984). However, no dis- Salvelinusfontinalis), however reportee ,ar feedo t d ease is known to be specific for M. relicta. Smith heavily on mysids (J. Johnson, Utah Department and Lankester (1979) discovered thamysie th t d of Wildlife Resources, personal communication) is an intermediate host of the swim bladder nema- and may prove to be useful control agents in the tode Cystidicola cristivomeri, t laboratorbu - yob future. Presently, t splakoccuno - o re d wit re . hM servation t indicatno d sdi e tha infectioe th t s nwa licta mann i y places theid an , r interactions with lethal. Smith and Lakester (1979) found that mor- mysidt welno l e documentedsar . tality was high when M. relicta was experimentally Attribute Candidatf so e Control Species infected by C. farionis, another swim bladder nematode that has an amphipod as an interme- Amphipods diate host. Release of such a parasite to attack Lik . relicta,eM amphipode th s Pallasea qua- mysids appears to be of uncertain value and poses drispinosa d Pontoporeiaan affinise considerear d threaa fisheso t . true glaciomarine relicts. Pontoporeia affinis has a Other types of biological mysid control—intro- circumpolar distribution simila re-thaM o rt f o t ductions of predators and competitors—seem more licta\ Pallasea quadrispinosa restrictes i northdo t - promising, although such control vectors would Eurasin er a (Segerstrale 1962). Pontoporeia affinis themselves have to be exotic species in western occurs with Mysis relicta mann i y North American waters have .W e compared selected characteristics lakes (Ricker 1959), and all three species occur in of Mysis relicta with thos othe2 f eo r crustaceans some Scandinavian and Russian waters (Seger- 1d 1 an fishes that migh able b tcontro o et l mysid strale 1962). populations through competition or predation Furst (1981) provided informatio e mosth f o t n (Tables 2-4). Crustaceans were selected that have availabl Pallasean eo quadrispinosa introductions. close association with benthic M. relicta in its na- In Sweden, this amphipo bees dha n introduced tive range. Fish species were chosen that are known wit . relictahM improvo t e fish forage. Despits eit

TABLE 2.—Selected species characteristics of Mysis relicta compared with thospotentias it f eo l competitord san predators.

Niche Size at maturity Maximum size Species Zone8 Behavior5 Trophic levelc (mm)d (mm)6 Mysis relicta B,L,P E,V O,P,D 14-22 30 Pallasea quadrispinosa B E D 10-20 30 Pontoporeia affinis B E,B D 5-8 10 Alewife L P,S P,F 120-180 280 Lake herring L,P P,S P 200-300 380 Lake whitefish UP P,D P,B 350-460 610 Bloater P D,P P,B 170-260 300 Pygmy whitefish L D P3 100-130 250 Arctic char UP P P3 380-450 640 Lake trout P P F,B 400-560 1,200 Rainbow smelt L P,S P 130-200 300 Burbot P D F,B 280-480 890 Slimy sculpin B D,E B 70-90 150 Deepwater sculpin B D,E B 60-80 130 Vertical position typically occupie waten di r column =B : benthic =L ; limnetic profunda= P ; l ba Characteristic activities displaye availabln di e habitat burrowing= :B demersal= ;D -;E epibenthic pelagic= ;P =;S schooling; V «= vertical migration. c Feeding habits - benthivorous:B detritivorous= D ; piscivorous= F ; omnivorous= ;O planktivorous= ;P . Crustacean lengths were measure rostrumf o d telsof p froo ti p mo ti nt ; fish siz totas ei l length. ed Approximate maximum length typically attained by the species. BIOLOGICAL MANAGEMEN MYSISF TO RELICTA

TABLE 3.—Reproductive characteristics of Mysis relicta and of its potential competitors and predators. NA not applicable.

Spawning Habitat Fecundity Hatch- Loca- Thousands Egg Species Timing3 ^ inga>c tiond Substrate6 Depthf Age* ofeggsh type1 Mysis relicta F NA V L P NA I-1V 0.010-0.035 NA Pallasea quadrispinosa W NA V L P NA I-III ? NA Pontoporeia affinis W-S NA S L P NA I-II 0.015-0.040 NA wife Al e 5-7 15.5 6d L,S S,G S II-III 10-22 D Lake herring 10-12 4.5 4 L S,G,C S II-III 6-20 B Lake whitefish 10-12 5.0 5 L,S S,G S III-IV 8-25* B Bloater 3 1.5 6 L S,G,C D II-III 4-8 B Pygmy whitefish 10-12 4.5 S L,S G S II-III 0.4-0.6 D Arctic char 11-12 4.0 4 L,S G S IV-VI 1.9-3.5* D Lake trout 10 11.0 3 L C,B S V-VII 0.9-2.6* D Rainbow smelt 3-5 10.0 3w S,L G S II-III 8-30 A Burbot 1-3 1.0 5 L,S S,G S III-IV 50-1,500 B Slimy sculpin 5-6 5.0-10.0 7 S,L N S II-III 0.2-1.4 A Deepwater sculpin 12-5 1.0 2-7 L N D II-III 0.2-1.2 A Approximate seaso spring= V nsummer( = ;S winter = fall = F W ,; number )o monthf depositionro g eg f so . ab Water temperatures associated with spawning activity. c Approximate mont seasor ho releasf no hatchingyounf g eo eg r go duratior o , incubationf no days = weeks= :d ;w . d Major habitat selected for spawning: L = lake; S = stream. Substrate types depositionselecteg eg r dfo =:P brood pouch sand = gravel= ; S cobble;G = ;C boulder= ;B nest= ;N . cr Relative spawning depth: S = shallow; D = deep. (yearse 8Ag t maturity)a . h Average number of eggs per female or average egg number per kilogram of female (*). behaviog Eg ' r upon deposition adhesive= :A semibuoyant= B ; demersal= D ; . higher birth rates, however, its populations do not reac e surfacth h e (Mundie 1959; Wells 1960). develo quickls pa r reacyo h densitie greas sa s a t Marzolf (1965b), who found that not more than myside thosth f eo . This differenc bees - ha en at 7% of the P. affinis population in Lake Michigan tributed to intense fish predation on the amphi- migrated int watee oth r colum nightt na , conclud- pod, possibly becaus largs i t ei e (Tabldoed an s) e2 ed that these migrations of predominantly adult not burrow into the substrate. Pallasea quadri- subaduld an t instarr s fo wer t matinr no efo d gan spinosa does not make vertical migrations but feeding. This amphipod feeds nonselectively by swims just abov bottoe eth t mnighta . Onc- ees ingesting large quantities of bottom sediment tablished t seemi , havo st e more positive effects (Marzolf 1965a). on fish populations than does M. relicta—proba- Though Mysis relicta d Pontoporeiaan affinis bly because its influence on zooplankton com- most commonly live in well-oxygenated hypolim- munities is minor and it is available to fish, in- netic waters, Juday and Birge (1927) found the cluding species tha littorae t feeth n di l zone (Furst amphipod tolerant of low oxygen concentrations 1972a). (< 1 mg/L). Mysis relicta, however, dies at oxygen Pontoporeia affinisburrowea s i r (Marzolf 1965a) concentrations below 2 mg/L (Sherman et al. 1987). that remains almost entirely on and in the bottom W. SmitE . h (1972) reported thamaximue th t m during daylight (Wells 1968a; Robertso t alne . temperature tolerated by P. affinis in the labora- 1968) oftes i mos e t .I n th t abundant benthic mac- tory was about 11°C Larkin (1948) found that roinvertebrate in many glaciated lakes, composing reproduction by P. affinis was inhibited in Atha- 50-80% of all macroinvertebrates on or near the baska, Great Bear, and Great Slave lakes by tem- botto mseveran i l Canadian lakes (Rawson 1953), peratures above 7°C. This amphipod appearo st in the St. Lawrence Great Lakes (Cook and John- be less tolerant of high water temperatures than son Lak1974)n i d e an Vatter, n (Grimas 1969). M. relicta, which has been collected in surface diee Th l vertical migration f Pontoporeiaso af- waters at 20°C (Mundie 1959). Thus P. affinis pre- finis are shorter than those of M. relicta. Large sumably would occur at the greater depths in lakes number mysidf so entey uppee sma rth r stratf ao and reservoirs where temperatures and dissolved lake . affinist nightsa P t bu , remains largely below oxygen concentration bote sar h low. the metalimnion and relatively few individuals importance Th e of Pontoporeia diete affinisth sn i MARTINEZ AND BERGERSEN

TABLE 4.—Management consideration Mysisr sfo relicta compared with potentias thosit r efo l competitord san predators. NA = not applicable.

Introductions Populations Potential Acquisi- Controlla- Species History8 tion13 Vagility0 Number* Stability6 bilityf Fishery* Forageh Disease* Mysis relicta W S M H M L NA H L Pallasea quadrispinosa L F L M L H NA H H Pontoporeia affinis L F L H L L NA H H Alewife W S H H H L L H H Lake herring L S L H L L M H H Lake whitensh L S M H L L M M H Bloater N S L M L L L H H Pygmy whitensh N D H M L L NA H H Arctic char W S M M L H H L M Lake trout W S L L L H H L M Rainbow smelt W S H H M M M H H Burbot N F M M L M M L H Slimy sculpin N D M H L L NA H H Deepwater sculpin N D L H L L NA H H a Previous introduction attempts =:N none —L ; limited —;W widespread. b Relative availability: S = simple; F = feasible; D = difficult. c Propensity for dispersion or colonization (self-introduction): L = low; M = moderate; H = high. d Relative abundanc speciee e achievth environmenty w sma ne n ei low= =:L M ; moderate high= H ; . c Relative variation in population numbers over time: L = low; M » moderate; H = high. f Capacity to manage population levels once established: L = low; M = moderate; H = high. 8 Relative capacity of species to provide sport harvest: L = low; M = moderate; H = high. h Relative suitabilit specief yo fiss sa h forage lowmoderate= = L : M ; «;•H high. ' Potentia transmittar fo l majof o l r pathogen parasitesr so moderatelow= = :L M ; high= H ; . of many fish species is well documented (Scott and these species to increase predation on mysids may Crossman 1979). Because of its close association also enhanc efishera supplementiny yb g foragr eo with the substrate, preference for cold water, and sport-fish populations. Before destructive pertur- detritus diet, P. affinis should have a more pre- bations occurre Greae th n dti Lakes fooe b ,th dwe dictable effec establishedf i t providy ma d ea an , composed of large invertebrates (Mysis relicta and more reliable food source for fish, than would M. Pontoporeia affinis) younr fo g lake trou muld tan - relicta. Brownell (1970) advised cautioe th n ni tispecies forage (coregonine cottidsd san largr )fo e transfer . affiniso fP water o t s wher acanthoe eth - lake trout was believed to be the most stable and cephalan Echinorhynchus salmonis is not already productive predator-prey system in the Great present, because the amphipod is an intermediate . LakeSmitH . hs(S 1972). host for this fish parasite. alewife Th e Alosa pseudoharengus appearo t s If thes amphipodo etw s were introduced into have invaded many lakes containing natura- my l Colorado waters, they might compete with Mysis populationd si s (Miller 1957; Young Oglesbd san y relicta for food (detritus) and space. Grimas et al. 1972) Lakn I . e Michigan verticae th , l migration (1972) reported rapid growth rates for most fish of alewive adaptation s believei a s e b o r dt nfo species in Lake Vattern, Sweden, where Mysis re- feeding on vertically migrating mysids. Adult ale- licta, Pontoporeia affinis, and Pallasea quadrispi- wives also feed extensivel . relictaM n t ynigho a t nosa occur together. Chars, trouts, and whitefishes (Jansse Brandd nan t 1980). Despite this appar- fed on these glacial relicts, which were believed to ently perfect match of predator and prey and the contribut "idean a eo t l food web botr "fo h pelagic- nominatio alewiff no Leathy eb e (1984 speciea s )a s and bottom-feeding predators. capable of controlling problem mysid populations, other aspects of alewife ecology are discouraging. Fish Alewive extremele sar y efficient feeders (Janssen 1e 1 fisTh h species liste Tabledn i s 2-4 pren yo 1978) that can induce shifts in zooplankton com- Mysis relicta, and several, including Arctic char positio sizd nean distribution toward smaller forms; Salvelinus alpinus, rainbow smelt Osmems mor- such shifty adverselma s y affect other plankti- dax, burbot Lota lota, sculpind an s Myxocephalus vores, including young-of-year sport species (Koh- spp., have circumpolar distributions (Scotd an t ler and Ney 1981). Alewives are also considered Crossman 1979). Introductio r moro e f eo on f no potentially important predators on fish larvae, and BIOLOGICAL MANAGEMEN MYSISF TO RELICTA

may have contributed to the collapse of certain to be responsible for their faster-than-usual growth, native Great Lakes fish populations (Crowder 1980; but consumption decreased among older fish 1980)y KohleNe (1980d .y Kohlean rNe d ) an r (Griest 1976) Lakn .I e Tahoe, mysid consumption suggested that this characteristi e alewifth f co e produce significano dn t improvemen lakn ti e trout should be seriously considered before the species condition, but the fish ate mysids to the exclusion is introduced elsewhere. Landlocked alewife pop- of traditional food sources such as crayfish and ulation subjece sar periodio t c mass die-offs (Koh- fish (Morgan et al. 1978). Further lake trout in- 1981)y thed Ne d ,lean y rreadilan y spread through troductions shoul consideree db d carefull avoio yt d lakreservoid ean r systems (Ne t alye . 1982). complicating or precluding the establishment of Pelagic lake herring Coregonus artedii and pro- forage specie essentiae b s y tha effectivr ma t fo l e fundal bloaters Coregonus hoyi knowe ar feeo nt d mysid control. heavil mysidn yo s (Scot d Crossmaan t n 1979). rainboe Th w smel anadromouss i t t indigebu , - Rawson (1951) showed that lake herring wern ea nous landlocked populations also occur. This fish important link between mysids and large preda- offers limited recreational fishing opportunities, tor Grean si t Slave Lake, Ontario Laken .I s Mich- bees ha n t widelbu y introduce pres dmana r yfo y igan and Superior, large bloaters feed heavily on fish species. Mysis relicta primara s i y foo rainf do - mysids throughout the year (Dryer and Beil 1968); bow smelt (Scot Crossmad an t n 1979). However, these fish eat both plankton and benthos (Janssen rainbow smelt are suspected predators of small fish 1978). Although lake whitefish Coregonus clupea- (Scot Crossmad tan n 1979; Crowder 1980). Jones formis d pygman y whitefish Prosopium coulteri (1985) indicated that young rainbow smeln i t also eat plankton, they are typically benthic feeders Horsetooth Reservoir, Colorado, competed with (Lindsey 1981) that readily consume mysids game fiszooplanktonr hfo , whereas larger rainbow (Eschmeye Bailed ran y 1955; Johnson 1975- ;Wy smelt (longer than 80 mm) ate primarily mysids. doski and Bennett 1981). Because lake whitefish Because rainbow smelt are capable of exploiting a stock extremele sar y adaptabl thein ei r feedin- gbe wide variety of foods, their introduction into waters havior (Lindsey 1981 pygmd )an y whitefish have where stockin f planktivorougo r younso g fiss i h highla y disjunct distribution (Lindse Frand yan - important in the management of a fishery should zin 1972) selectioe ,th donof no r sources from lakes be carefully considered. Caution in the use of rain- where these species coexist with Mysis relicta bow smelt also is advised because the species ap- should be considered. pearhighle b o st y vagile (Bur Mayded ran n 1980; When Mysis relicta has been introduced into Suttkus and Conner 1980). lakes and reservoirs containing Arctic char and All sizes of burbot feed on Mysis relicta, but lake trout resulte th , s have been mixed (Gosho large burbot are primarily piscivorous and are be- 1975; Furst 1981; Lasenb . 1986)al t ye . Arctic char lieve competo dt e with other predaceous species and lake trout are sport species that might be more for food (Bailey 1972; Scott and Crossman 1979). widely introduced to prey on mysids. Populations Burbot are often regarded as "rough fish." In Wy- Arctif o c char differ considerably (Kornfiel. al t de oming, however, this specie manages i gama s da e 1981) donoo s , r stocks probably shoul takee db n fish because of its potentially large size (Bjorn 1940) from water whicn si h Arctic char coexist witd han and excellent food quality (Baxter and Simon t M.ea relicta. Mucinformatioe th f ho intern no - 1970). Manager consideo swh r transplanting bur- action f Arctio s c chad mysidan r s comes from bot should think about the species' potential effect Scandinavia, where Arctic char are littoral and on existing fisheries and on future introductions profundal benthivores and limnetic planktivores of other species. (Lasenb . 1986)al t ye . Generally, planktivorous The slimy sculpin Coitus cognatus is widespread Arctic char compett e ea wit t hno mysido d t sbu in lakes and streams of northern North America. them, whereas benthic-feeding Arctic char usually The deepwater sculpin Myoxocephalus thompsoni feed heavily on introduced mysids (Furst 1981; appears to be restricted exclusively to deep, cool Langeland 1981) Arctil .Al c char, however, appear lakes within or near basins of formerly glaciated to feed most heavily on mysids under winter ice lakes (Scot Crossmad tan n 1979) deepwatee Th . r cover (Furst 1972a; Lasenby et al. 1986). sculpin, like Mysis relicta, is generally referred to Mysis relicta is an important food of lake trout ,trua s ea glacial relict Bailet ,bu Smit d yan h (1981) particularly of the young (Scott and Crossman indicated this reference to be incorrect. However, 1979). Juvenile lake trou Twin i t n Lakes, Colo- M. relicta and the deepwater sculpin have similar rado, fed primarily on mysids, which was believed distribution Nortn si h America mysidd ,an s occur 8 MARTINE BERGERSED ZAN N

in all waters known to contain deepwater sculpins didates for introduction should not transfer con- (McAllister 1961; McAllister and Ward 1972; tagious diseases or parasites exotic to the system. Dadswell 1972). Deepwater sculpins typically live All of the species discussed have been cultured in in deeper water than that occupied by slimy scul- hatchery or laboratory facilities. As is commonly pins (Wells 1968b; Johnson 19 Scot; 7 5 Cross d tan - practice salmonidn i d culture, eggs shoul treate db - 1979)n ma . Both species fee Mysisn do relictad an whed e n thi feasibls si precludo et transfee eth f o r Pontoporeia affinis (Kraft 1977; Wells 1980; Kraft diseases and parasites (Kohler and Stanley 1984). Kitcheld an l 1986) t slim,bu y sculpins ten feedo t d capacite Ifth reao yt r the mdevelopeds i - ac e th , on a wider variety of benthic organisms (Scott and quisition, propagation, introduction, and estab- Crossman 1979). Although deepwater sculpint sea lishment of these species would be facilitated. For other benthic animals (Jacoby 1953; Scotd an t species that are difficult to culture, donor sources Crossman 1979), their diet often consists almost shoul selectee db d carefull fisd hyan shoul hele db d entirel mysidf yaffinis. o P d san (Kraft 1977; Wells in isolatio inspectionfor minimiznto e risks from 1980). Slimy sculpins generally eat more P. affinis disease parasitesd san . and fewer mysids than deepwater sculpins (Kraft 1977; Kraft and Kitchell 1986). Acknowledgments Recommendations We thank Robert Behnke for his guidance in In the selection of additional exotic organisms this review. Also recognized are the fishery per- stoco t lakea protocole n ki th , s prescribei L y db sonne provideo wh l d informatio e introth n -o n Moyld an e (1981 Kohled )an Stanled ran y (1984) duction and establishment of Mysis relicta in west- shoul e considereb d d before introductione ar s Nortn er h America speciaA . l thank extendes si d to Anita Martinez for her assistance in producing made. First amon recommendatione gth s listey db Li and Moyle (1981) is that candidates for intro- this manuscript. duction shoul coadapatea pare db f o t d trophic assemblage involving species already present in References the system. This guideline was violated in the . Bailey1972M . M , . Age, growth, reproductiond an , widespread introduction of Mysis relicta outside burbote footh f do , Lota lota (Linnaeus) southn i , - its native range (Lasenb t alye . 1986); introduced western Lake Superior. Transaction Amere th f so - lake trout often were the only fish present that had ican Fisheries Society 101:667-674. coevolved wit myside hth . e specieNonth f eo s Bailey, R. M., and G. R. Smith. 1981. Origin and ge- ography of the fish fauna of the Laurentian Great discussed here is proposed as the sole solution for Lakes basin. Canadian Journa f Fisherieo l d an s mysid problems .candidate e Howeverb y ma l sal , Aquatic Sciences 38:1539-1561. for species complexes that migh developee b t o dt Baxter, G. T., and J. R. Simon. 1970. Wyoming fishes. control introduced mysids. Kohler and Stanley Wyoming Gam Fisd ean h Commission Bulleti. n4 (1984) recommended that species proposed for in- . BowersBeetonA . J . M.d .A , an , 1982. Vertica- mi l troduction matc neede hth . Becaus deepwatee eth r gration of Mysis relicta Loven. Hydrobiologia 93: sculpin provide majoe sth r link between mysids 53-61. Berrill . LasenbyC . D , M.d .,an 1983. Life cyclee th f so lakd an e troua straight n i t , simple food chain freshwater mysid shrimp Mysis relicta reareo tw t da (Johnson 1975) t representi , logicasa l first choice temperatures. Transactions of the American Fish- for introduction into waters where the lake trout eries Society 112:551-553. onle th ys i species coadapted with M. relicta. Bjorn, E. E. 1940. Preliminary observations and ex- The second and third recommendations out- perimental study of the ling, Lota maculosa (Le- Moyld an i lineeL (1981y db thae )ar t candidate Sueur), in Wyoming. Transactions of the American Fisheries Society 69:192-196. species have narrow niche breadth and low vagil- Brownell, W. N. 1970. Comparison of Mysis relicta ity. Aside from amphipods deepwatee ,th r sculpin Pontoporeiad an affinis possibls a e intermediate hosts appear beso st t fulfill these criteria benthia s i t .I - for the acanthocephalan Ehinorhynchus salmonis. vore tha restrictes i t cole th d o dt depth lakef so s Journal of the Fisheries Research Board of Canada and should, therefore, not spread to other waters 27:1864-1866. r seriouslo y compete with sport species. Because Burr, B. M., and R. L. Mayden. 1980. Dispersal of rainbow smelt, Osmerus mordax, inte uppeoth r of its affinity for mysids and deep water, the deep- Mississippi River (Pisces: Osmeridae). American water sculpin again represents a good candidate Midland Naturalist 104:198-201. for introduction. Carpenter, G. F., E. L. Mansey, and N. H. F. Watson. Lastly, Li and Moyle (1981) suggested that can- 1974. Abundance and life history of Mysis relicta BIOLOGICAL MANAGEMENT OF MYS1S RELICTA

in the St. Lawrence Great Lakes. Journal of the Fish- Angeli. 1979. A population dynamics analysis of eries Research Boar Canadf do a 31:319-325. the cladoceran disappearance from Lake Tahoe, . . SpangesM R . Hurley. . A A G Colby . , d D ,J. an ,. P , California-Nevada. Limnology and Oceanography McCombie. 1972. Effect eutrophicatiof so saln no - 24:289-297. monid communities in oligotrophic lakes. Journal Gosho . 1975 E e introductio. Th M , . n of Mysis relicta of the Fisheries Research Board of Canada 29:975- into fresh water lakes. Universit f Washingtonyo , 983. Fisheries Research Institute, Circular 75-2, Seattle. Cook, D.G. M.G.Johnsond ,an . 1974. Benthic macro- Griest . 1976R lake . ,J eTh . trou Twif to n Lakes, Col- invertebrates of the St. Lawrence Great Lakes. Jour- orado. Master's thesis. Colorado State University, nal of the Fisheries Research Board of Canada 31: Fort Collins. 763-782. Grimas, U. 1969. The bottom fauna of Lake Vattern, Cooper, S. D., and C R. Goldman. 1980. Opossum central Sweden somd ,an e effect eutrophicationf so . shrimp (Mysis relicta) predatio n zooplanktonno . Institut f Freshwateo e r Research Drottningholm Canadian Journal of Fisheries and Aquatic Sciences Report 49:49-62. 37:909-919. Grimas, U., N.-A. Nilsson Wendt. C d ,an . 1972. Lake Crowder, L. B. 1980. Alewife, rainbow smelt, and na- Vattern: effects of exploitation, eutrophication, and tive fishes in Lake Michigan: competition or pre- introductions on the salmonid community. Journal dation. Environmental Biolog Fishef yo s 5:225-233. of the Fisheries Research Board of Canada 29:807- Dadswell, M. J. 1972. Postglacial dispersal of four 817. deepwater fishes on the basis of new distribution Grossnickle, N. E. 1979. Nocturnal feeding patterns of records in eastern Ontario and western Quebec. Mysis relicta Lakn i e Michigan, conten t basegu n do t Journa Fisheriee th f o l s Research Boar Canadf do a fluorescence. Limnology and Oceanography 24:777- 29:545-553. 780. DeGraeve, G. M., and J. B. Reynolds. 1975. Feeding Jacoby, C. 1953. Notes on the life history of the deep- behavior and temperature and light tolerance of'My- water sculpin, Myoxocephalus quadricornis, in Lake sis relicta in the laboratory. Transactions of the Superior. Master's thesis. University of Michigan, American Fisheries Society 104:394-397. Ann Arbor. De Henau, A. M. 1981. A study of the feasibility of Janssen, J. 1978. Feeding-behavior repertoire of the introducing Mysis relicta Loven 1862 into the Spray alewife, Alosapseudoharengus. and the ciscoes, Cor- Lakes Reservoir. Alberta Fish and Wildlife Division egonus . artedii.C hoyid an Journa Fisheriee th f o l s and Alberta Energ Naturad yan l Resources, Plan- Research Board of Canada 35:249-253. ning Documen , Calgary9 t , Canada. Janssen . BrandtB . S ,d .J. an ,1980 . Feeding ecology . DryerBeilJ d . R.. an W , 1968. Growth changef so verticad an l migratio adulf no t alewife (Alosa pseu- the bloater (Coregonus hoyi) of the Apostle Islands doharengus) in Lake Michigan. Canadian Journal regio Lakf no e Superior. Transaction Amere th f so - of Fisheries and Aquatic Sciences 37:177-184. ican Fisheries Society 97:146-158. Johnson, L. 1975. Distribution offish species in Great Bailey. M . EschmeyerR . d 1955 an pygme , Th H. . . y,P Bear Lake, Northwest Territories, with referenco et whitensh, Coregonus coulteri, in Lake Superior. zooplankton, benthic invertebrates, and environ- Transactions of the American Fisheries Society 84: mental conditions. Journa lFisherie e ofth s Research 161-199. Board of Canada 32:1989-2004. Finnell, L. M. 1977. Fryingpan—Arkansas fish re- Jones. S 1985 . M , . Age, growth food walleyef an ,do , search investigations. Colorado Division of Wild- smallmouth bass smeld an ,Horsetoot n i t h Reser- life, Final Report, Fort Collins. voir, Colorado. Master's thesis. Colorado State Uni- . CordoneJ Frantz . A . d C.T , an ,. 1970. Food of lake versity, Fort Collins. trout in Lake Tahoe. California Fish and Game 56: Juday, C, and E. A. Birge. 1927. Pontoporeia and My- 21-35. sis in Wisconsin lakes. Ecology 8:445-451. Furst, M. 1972a. Experiments on the transplantatio . NeyJ . J n . d 1980an Kohler , .C . PiscivoritC , a n yi of new fish-food organisms into Swedish impound- landlocked alewife (Alosa pseudoharengus) popu- ed lakes. The feeding habits of brown trout and char lation. Canadian Journal of Fisheries and Aquatic in Lake Blasjon. Internationale Vereinigung fuer Sciences 37:1314-1317. Theoretische und Angewandte Limnologie Ver- Kohler, C. C, and J. J. Ney. 1981. Consequences of handlungen 18:1114-1121. alewifn a e die-of zooplanktofisd o ft han maina n i - Furst . biologe 1972b opossu,M e th th n f yO o . m shrimp stream reservoir. Transaction e Americath f o s n Mysis relicta s introductioit Love d - an n im n i n Fisheries Society 110:360-369. pounded lake Scandinavian i s . Acta Universitatis Kohler, C. C, and J. G. Stanley. 1984. A suggested Upsaliensis, Abstracts of Uppsala Dissertations in protocol for evaluating proposed exotic fish intro- Science 207. duction Unitee th n si d States. Pages 387-40. W 6n i Furst . 1981M , . Result f introductionso fisw hne f so R. Cortenay, Jr., and J. R. Stauffer, Jr., editors. Dis- food organisms into Swedish lakes. Institutf o e tribution, biology and management of exotic fishes. Freshwater Research Drottningholm Repor: 59 t Johns Hopkins University Press, Baltimore, Mary- 33^7. land. Goldman, C. R., M. D. Morgan, S. T. Threlkeld, and N. Kornfield, L, K. F. Beland, J. R. Moring, and F. W. 10 MARTINE BERGERSED ZAN N

Kircheis. 1981. Genetic similarity among endemic Marzolf . 1965bR . G , . Vertical migratio f Ponto-no Arctic char (Salvelinus alpinus) implicationd an r sfo poreia affinis (Amphipoda) in Lake Michigan. Pro- their management. Canadian Journal of Fisheries ceedings, Conference on Great Lakes Research 13: and Aquatic Sciences 38:32-39. 133-140. Kraft, C, and J. F. Kitchell. 1986. Partitioning of food McAllister . 1961E origie . statud e Th D , .nth an f so resource sculpiny sb Lakn si e Michigan (USA)- .En deepwater sculpin, Myoxocephalus thompsonii,a vironmental Biology of Fishes 16:309-316. Nearctic glacial relic. National Museu Canadaf mo , . KraftE 1977 . C , . Comparative trophic ecologf o y Bulletin 172:44-65. deepwater sculpins (Myoxocephalus quadricornis) McAllister Ward. C . J d E.. ,D 1972,an deepwate e Th . r and slimy sculpins (Cottus cogantus) in Lake Mich- sculpin, Myoxocephalus quadricornis thompsoni, new igan. Master's thesis. University of Wisconsin- to Alberta, Canada. Journa e Fisherieth f o l- sRe Madison, Madison. search Board of Canada 29:344-345. LaBounty, J. F., J. J. Sartoris, S. G. Campbell, J. R. Miller . 1957R . R , . Origi dispersad nan alewifee th f lo , Boehmke. RolineA . R d . an ,1980 . Studiee th f so Alosa pseudoharengus, and the gizzard shad, Dor- effect operatinf o s. ElberMt e tg th pumpe d storage osoma cepedianum, in the Great Lakes. Transac- powerplant on Twin Lakes, Colorado: 1979 report tions of the American Fisheries Society 86:97-111. of findings. Water and Power Resources Service, Morgan, M. D., editor. 1982. Ecology of Mysidacea. Report REC-ERC-80-7, Denver, Colorado. Dr. W. Junk, The Hague. Langeland . 1981A , . Decreased zooplankton density Morgan, M. D., C. R. Goldman, and R. C. Richards. Norwegiao intw n lakes cause predatioy db - re f no 1981. Impac f introduceo t d population f Mysisso cently introduced Mysis relicta. Internationale Ver- relicta zooplankton o n oligotrophini c subalpine einigung fuer Theoretische und Angewandte Lim- lakes. Internationale Vereinigung fuer Theoretische nologie Verhandlungen 19:835-842. und Angewandte Limnologie Verhandlungen 21: Larkin, P. A. 1948. Pontoporeia and Mysis in Atha- 339-345. baska, Great Bea Gread ran t Slave lakes. Fisheries Morgan . . ThrelkeldGoldman T R . D. . . M S ,C d an ,. Research Boar Canadf do a Bulleti. n78 1978. Impact of the introduction of kokanee (On- Lasenby, D. C., and R. R. Langford. 1972. Growth, corhynchus nerka) opossud an m shrimp (Mysis- re life history respiratiod an , f Mysisno relictan a n i licta)subalpina n o e lake. Journa Fisheriee th f lo s arctic and temperate lake. Journal of the Fisheries Research Board of Canada 35:1572-1579. Research Boar Canadf do a 29:1701-1708. Mundie, J. H. 1959. The diurnal activity of the larger Lasenby, D. C., and R. R. Langford. 1973. Feeding invertebrates at the surface of Lac la Ronge, Sas- assimilatiod an f Mysisno relicta. Limnologd yan katchewan. Canadian Journal of Zoology 37:945- Oceanography 18:280-285. 946. Lasenby, D. C., T. G. Northcote, and M. Furst. 1986. Murtaugh, P. A. 1981. Selective predation by Neomysis Theory, practice, and effects of Mysis relicta intro- mercedis n Laki e Washington. Limnologd an y duction Norto st h America Scandinaviad nan n lakes. Oceanography 26:445-453. Canadian Journa Fisherief lo Aquatid san c Sciences Nelson, W. C. 1981. Large lake and reservoir limno- 43:1277-1284. logical studies. Pages 6-8 in O. B. Cope, editor. Leathe, S. A. 1984. Opossum shrimp: a controversial Colorado fisheries research review 1978-1980. Col- new residen Flatheaf o t d Lake. Western Wildlands orado Division of Wildlife, Fort Collins. 9:10-14. Nero, R. W., and D. W. Schindler. 1983. Decline of Leathe, S. A., and P. J. Graham. 1982. Flathead Lake Mysis relicta during the acidification of Lake 223. fish food habits study. Montana Departmen Fishf to , Canadian Journal of Fisheries and Aquatic Sciences Wildlife and Parks, Final Report. Kalispell. 40:1905-1911. . MoyleB . P .d 1981an , W. Li. . H , Ecological analysis Nesler,T. 1986. ASjtfto-gamensh studies. Colorado Di- of species introductions into aquatic systems. Trans- vision of Wildlife, Federal Aid Project F-83, Fort actions of the American Fisheries Society 110:772- Collins. 782. Lindsey . 1981C . C , . Stock chameleonse sar : plasticity Nigro. A Ney. Kohler . C A J.. . .J , ,C d 1982,an . Land- in gill rakers of coregonid fishes. Canadian Journal locked alewife in Claytor Lake, Virginia: evaluation of Fisheries and Aquatic Sciences 38:1497-1506. foraga s a e specie inlanr sfo d waters. Virginia Poly- . Franzin.G . W d Lindseyan 1972 , comC w . .C ,Ne - technic Institute and State University, Management plexitie zoogeographn si taxonomd yan pyge th f -yo Publication 4, Blacksburg. my whitefish (Prosopium coulteri). Journae th f o l Northcote, T. G. 1972. Some effects of mysid intro- Fisheries Research Boar Canadf do a 29:1772-1775. duction and nutrient enrichment on a large oligo- Martinez . J 1986 . P , . Zooplankto kokaned nan e inter- trophi salmonidss cit lakd ean . Internationale Ver- actions in Lake Granby, Colorado, and management einigung fuer Theoretische und Angewandte of introduced Mysis. Master's thesis. Colorado State Limnologie Verhandlungen 18:1096-1106. University, Fort Collins. Parker, J. I. 1980. Predation by Mysis relicta on Pon- Marzolf, G. R. 1965a. Substrate relations of the bur- toporeia hoyi: a food chain link of potential impor- rowing amphipod Pontoporeia affinis in Lake Mich- Greae tancth n tei Lakes. Journa f Greao l t Lakes igan. Ecology 46:579-592. 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Pennak, R. W. 1978. Freshwater invertebrates of the Great Lakes. Journal of the Fisheries Research Board United States. Wiley Yorkw Ne , . of Canada 29:717-730. Rawson . 1951S . D , . Studie fis e Greaf hth o f so t Slave Smith, W. E. 1972. Culture, reproduction, and tem- Lake. Journal of the Fisheries Research Board of perature tolerance of Pontoporeia labe affinisth -n i Canada 8:207-240. oratory. Transaction Americae th f so n Fisherie- sSo Rawson . 1953 S bottoe . D , Th . m faun Greaf ao t Slave ciety 101:253-256. Lake. Journal of the Fisheries Research Board of Sparrow, R. A. H., P. A. Larkin, and R. A. Rutherglen. Canada 10:486-520. 1964. Successful introduction of Mysis relicta Lov- Ricker, . KE 1959. glaciao e origitw Th f .n lo relict en into Kootenay Lake, British Columbia. Journal crustaceans of North America as related to Pleis- Fisheriee ofth s Research Board of Canada 21:1325- tocene glaciation. Canadian Journa Zoologf o l : y37 1327. 871-893. Conner. SuttkusV . J . D.d .R , an , 1980 rainboe Th . w . FalterRiemanM . C . d . E.1981B ,an , . Effecte th f o s smelt, Osmerus mordax, in the lower Mississippi establishment of Mysis relicta on the macrozoo- River nea . FrancisvilleSt r , Louisiana. American plankton of a large lake. Transactions of the Amer- Midland Naturalist 104:394. ican Fisheries Society 110:613-620. Wells, L. 1960. Seasonal abundance and vertical move- Robertson Anderson. Powers. F , F . A. . R ,C d ,an . 1968. ment f planktoniso c Crustace Lakn ai e Michigan. Direct observations on Mysis relicta from a sub- U.S. FisWildlifd han e Service Fishery Bulleti: n60 marine. Limnolog Oceanographd yan y 13:700-702. 343-369. . CrossmanJ . E Scott d . B.an W ,, . 1979. Freshwater Wells . 1968aL , . Daytime distribution of Pontoporeia fishes of Canada. Fisheries Research Board of Can- affinis off botto mLakn i e Michigan. Limnologd yan ada Bulletin 184. Oceanography 13:703-705. Sealing, C, and G. Bennett. 1980. Middle Park res-Wells . 1968bL , . Seasonal depth distribution of fisn hi ervoir studies. Colorado Divisio Wildlifef no , Fed- southeastern Lake Michigan. U.S. Fish and Wildlife eral Aid Project F-40-D, Final Report, Grand Junc- Service Fishery Bulletin 67:1-15. tion. Wells . 1980,L . Foo alewivesf do , yellow perch, spottail Segerstrale . 1962G immigratioe . S ,Th . prehisd nan - shiners, trout-perc slimd fourhord han yan n scul- glaciae torth f yo l relict Eurasif so Nortd aan h Amer- pin southeastern si n Lake Michigan. U.S. Fisd han ica. A survey and discussion of modern views. In- Wildlife Service Technical Paper 98:1-12. ternationale Revu gesamter ede n Hydrobiologi: e47 Wydoski, R. S., and D. H. Bennett. 1981. Forage species 1-25. in lakes and reservoirs of the western United States. Sherman . LasenbyC . Hollett. K.. L R , D , d an , . 1987. Transactions of the American Fisheries Society 110: Influenc f oxygeeo n concentratio distribue th n no - 764-771. tio f Mysisno relicta Love a temperat n i n e lake. . OglesbyYoungsT . R D.. d .,W an 1972. CayugaLake: Canadian Journal of Zoology 65:2646-2650. effects of exploitation and introductions on the sal- Smith, J.D., and M. W. Lankester. 1979. Development monid community. Journae Fisherieth f - o l Re s of swim bladder nematodes (Cystidicola spp. thein )i r search Board of Canada 29:787-794. intermediate hosts. Canadian Journal of Zoology Zyblut, R. E. 1970. Long-term changes in the limnol- 57:1736-1744. ogy and macro-zooplankton of a large British Co- Smith, S. H. 1972. Factors of ecologic succession in lumbia lake. Journa Fisheriee th f lo s Research Board oligotrophic fish communities of the Laurentian of Canada 27:1239-1250.