Transactions of the American Fisheries Society, volume 120, issue 3 (May 1991) pp. 368-381. ISSN 0002-8487 DOI: 10.1577/1548-8659(1991)120<0368:STSCFY>2.3.CO;2 http://afs.allenpress.com/perlserv/?request=get-archive http://afs.allenpress.com/archive/1548-8659/120/3/pdf/i1548-8659-120-3-368.pdf © American Fisheries Society Transactions Americane oth f Fisheries Society 120:368-381, 1991 Stocking Threadfin Shad: Consequences for Young-of-Year Fishes DENNIS R. DEVRiES,1 ROY A. STEIN, AND JEFFREY G. MiNER2 Ohio Cooperative Fish and Wildlife Research Unit3 and Department of Zoology The Ohio State University, Columbus, Ohio 43210,USA GARY G. MITTELBACH Kellogg Biological Station, Michigan State University Hickory Corners, Michigan 49060,USA Abstract.— Threadfin shad Dorosoma petenense commonle ar y introduced into reservoiro t s supplement prey availabl piscivorouo et s fishes determino T . earlw eho y life stage threadfif so n shad and their potential competitors and predators interact, we introduced this species into two Ohio lakes—Clark and Stonelick—and evaluated how its young of year influenced young-of-year bluegills Lepomis macrochirus and largemouth bass Micropterus salmoides. After adults were stocked in April, peak abundance of young-of-year threadfin shad occurred in August in both lakes. Bluegills generally spawned earlier than threadfin shad, which apparently reduced competition between young of these species. In Clark Lake, young-of-year threadfin shad did not reduce zoo- plankton populations, but in Stonelick Lake, peak abundance of young-of-year threadfin shad was followed by a precipitous decline in zooplankton. Data on cladoceran birth rates indicated this decline was due to increased predation by threadfin shad. Survival of bluegills to a size at which they move int littorae oth l zone also decline Stonelicn di k Lake, perhaps becaus virtuae th f eo l elimination of zooplankton. Limited survival of bluegills in turn contributed to reduced growth of young-of-year largemouth bass dependent on them as prey. Given that zooplankton declined othee th t r lakeno t ,bu interactione inon s among young-of-year annuall o fishet e sdu y introduced threadfin shad will likely vary among system yearsd san . Nonetheless, introduced threadfin shad could, in some systems in some years, negatively affect growth and recruitment of the very species they were meant to enhance. Manipulation of prey has become a popular described manipulations involving two clupeid technique for increasing production of sport fishes species (gizzard shad Dorosoma cepedianum and (Ney 1981; Noble 1981,1986; Wydoski and Ben- threadfin shad D. petenense) and four target spe- nett 1981; DeVrie Steid san n 1990). Manipula- cies (white crappie Pomoxis annularis, black crap- tions may involve the introduction of prey to in . nigromaculatus,-P e pi largemouth bass Microp- creas fooe eth d remova e basth r eo planktivoref lo s terus salmoides, and bluegill Lepomis macrochirus) reduco t e competition between the spord man t that resulted in positive, neutral, and negative ef- fishes. Numerous taxa have been used in these fects on the target species. Thus, introducing prey manipulations, including member Athere th f so - for predators or removing presumedly undesirable inidae, Catostomidae, Clupeidae, Coregonidae, competitor increast no y esma adult growt tarf ho - Cyprinidae d Percidaan , e (see referencen i s ge resuly t specie ma othern i t d san , unexpected DeVrie Steid san n 1990). These manipulations, consequences. based primarily on predator-prey interactions be- Because angler interestee sar largn di e fishe th , tween introduced prey and adults of the target spe- adult stag sporf eo t bees fishha n most studiedn i cies, sought to enhance the target sport species. relatio preo nt y manipulations. Other life stages However, enhancemen t alwayno s stha beee nth (larvae, juveniles pre f predator)d o yan s have been result. In a recent review, DeVries and Stein (1990) largely ignored (but see Kirk 1984; Kirk and Da- vies 1987). Because fish often change their diets and habitat thes a s y grow (Werne Gilliad an r m 1 Present address: Department of Fisheries and Allied 1984), species that interact as predator and prey Aquacultures, Auburn University, Auburn, Alabama adults a compety sma t earlieea r life stages- Ex . 36849, USA. 2 amples include largemouth bas bluegilld san s (Gil- Present address: Departmen f Zoologyo t , Miami liam 1982 Europead )an n perch Perca fluviatilis University, Oxford, Ohio 45056, USA. 3 The Unit is sponsored jointly by the U.S. Fish and and roach Rutilus rutilus (Persson 1988). Many Wildlife Service, Ohio Departmen f Naturao t - Re l fishes have Limnetic, zooplanktivorous larvae sources, The Ohio State University, and the Wildlife (Werner 1967; Barge Kilambd an r i 1980; Keast Management Institute. 1980; Beard 1982; Mills et al. 1987); where such 368 THREADFIN SHAD EFFECTS ON YOUNG OF YEAR 369 fishe introducee ar s preys da , competthey yma e during both stockings. Poststocking predatory during this life stage with larva f theieo r subse- mortalit largemoute monitores on y; wa d 3 r hdfo quent predators. Because year-class strength is collecte2 bas2 f so Clardn f 10i o 3e k Lakon d ean typicall t earlyse lifn yi e (Gushing 1975; Lasker collecte Stonelicdn i k Lak eated threade eha non - 1975; Ware 1980; Mill Forned san y 1988), inter- fin shad each r additionaFo . l details concerning actions during this critical perio havy dema major collection, transport stockind ,an g procedurese ,se effect sport-fisn so h surviva subsequend lan t har- Buynak et al. (1989) and Austin and Hurley (1989). vest. Thus, interactions at all life stages may de- Sampling methods.— samplee W d during April termine the success of any prey manipulation, the through October in preshad (1987) and shad (1988) overall outcome depending on some combination years. Because threadfin shad cannot overwinter of potential positive and negative effects. in Ohio lakes, any effects they have on resident We quantified how young bluegills responded fish must occur durin growine gth g season after introductioe toth n of threadfi nOhio shatw o dn i stocking. Larval fish (limnetic young-of-year fish demonstratee w lake d san potentiae dth negr fo l - susceptible to the sampling gear) were collected ative effects due to interactions among larvae. Be- offshore once per week in two replicate surface cause young-of-year bluegills are also important tows with a 0.75-m-diameter, 500-/ttm-mesh prer young-of-yeafo y r largemouth bass after ichthyoplankton net towed in the limnetic zone at moving into the littoral zone at a size between 10 1.5 m/s or faster. A flowmeter mounted in the standarm m 5 2 dd lengtan h (Werner 1967; Storck mouth of the net allowed calculation of the total 1978; Werne Hald ran l 1988) alse ,w o determined volume of water filtered. Juveniles were collected hoe offshorwth e interactio f bluegillo n s with biweekl t fouya r (Clark Lake r fivo ) e (Stonelick threadfin shad might indirectly affect growth and Lake) sites in the littoral zone with a 9-m bag seine surviva largemoutf lo h bass. (4-mm mesh) l fisAl h. were preserve- re d dan turnelaboratore th o dt y where they were identi- Methods fied and measured (total length to the nearest mm, Study lakes.— Clar d Stonelican k k lakee ar s up to 50 individuals per species), and their diets shallow, turbid reservoir southwestern si n Ohio. individual0 1 (u o pt r speciespe r datespe ) were Clark Lake Clarn i , k County0 are4 n a f ao s ha , quantified. Diets were quantified from weekly col- shorelinef hectareso m k 5 maximua ,4. , m depth lections of limnetic fish samples and from month- of 2 m, and Secchi depths varying from 25 to 75 ly collections of littoral samples (i.e., from every cm. Stonelick Lake Clermonn i , t Countyn a s ha , other sample date). We identified prey to the low- area of 69 hectares, 16 km of shoreline, a maxi- est taxonomic category possibl were % (>e80 iden- muSecchd an m , ideptm depth4 f ho s o frot 2 m2 tified to genus) and measured them to the nearest . Durin119cm studyr gou , submersed vegetation 0.1 mm. Lengths were converted to biomass by was never abundan eithen i t r lakemergend ean t usf taxon-specifio e c length-dry-weight regres- vegetation occupie shoreline th df abouo f % eo t25 . MittelbachsionG . s(G , unpublished data). Clark Lake (cattails Typha spp.) and 70% of the Integrated zooplankton samples (two tube hauls shorelin Stonelicf eo k Lake (Typha spp wated .an r sampler pe , three replicate sample dater spe ) were willow Justicia americana). Neither lake stratified collected with a 2-m tube sampler (7.30-cm inside thermally, and dissolved oxygen concentrations diameter, 54-/im mesh size; DeVries and Stein fell belo wmg/3 L botto e onlth yf o mwithi m 5 n0. sam1991e th t e)a time larval fish were collected. in Clark Lak Stonelicn beloi d ean m w2 k Lake. Samples were preserved in 5% sucrose formalin Fish communitie botn si h lakes consisted primar- (Haney and Hall 1973) to prevent cladoceran egg illargemoutf yo h bass, white crappies, bluegills, loss. Zooplankton taxa with less than 200 indi- longear sunfish Lepomis megalotis, brown bull- viduals per sample were counted in their entirety; head Ictalurus nebulosus, and common carp Cy- subsamples were take morr nfo e abundant taxa prinus carpio. until at least 200 individuals were counted. At In collaboration with personnel fro Ohie mth o least 20 individuals of each taxon in a sample were and Kentucky Departments of Natural Resources, measured (total body length excluding spines, hel- we stocked adult threadfin shad from Herrington mets caudad an , l rami) wit oculan ha r microme- Lake (Mercer County, Kentucky t densitiea ) f so ter.