Since the round goby was discovered in the St. Clair River in 1992, this aquatic invasive species has spread throughout the Great Lakes and Mississippi River Basins. This fact sheet provides information on this fish including ways you can help prevent the spread.Ope

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Round Gobies Invade North America

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FS-065By J. E.MarsdenIllinois Natural History SurveyDavid J. Jude University of Michigan Edited byRobin G.GoettelAgnes E.DillonIllinois-Indiana Sea Grant Reviewed byTed Cavender, Museum ofBiological Diversity, Columbus,Ohio;Jeff Gunderson, MinnesotaSea Grant, Duluth;Doug Jensen,Minnesota Sea Grant, Duluth;Carey Knight, Ohio Departmentof Natural Resources, Fairpor tHarbor; Clifford Kraft, Universityof Wisconsin Sea Grant Institute,Green Bay; Tom Lauer, PurdueUniversity, W. Lafayette, Indiana;and Dave MacNeill, New YorkSea Grant Institute, Brockport.The Great Lakes Sea GrantNetwork is a cooperativeprogram of the Illinois-Indiana,Michigan, Minnesota, New York,Ohio, and Wisconsin Sea Grantprograms. Sea Grant is a university-based program withinthe National Oceanic andAtmospheric Administration(NOAA) that is designed to support greater knowledge and well-informed, responsibledecisions about the resources ofthe Great Lakes, inland waters,and oceans.Through its network of advisoryagents, researchers, educators,and communicators, the GreatLakes Sea Grant Network sup-plies the region with usable solu -tions to pressing problems andprovides basic information need-ed to better manage the GreatLakes and inland waters for bothpresent and future generations.OHSU-FS-065 1995.This publication is produced by the I l l i n o i s-Indiana Sea Gra n tP r o gram in cooperation with the Michigan and Ohio Sea G rant College Programs as I L - I N - S G - 9 5 -1 0 .© The Ohio State UniversityPrinted on recycled paper.In the last decade, c o n s i d e rabl ep u blic and scientific at t e n t i o nhas been focused on the zeb ramu s s e l , an aquatic invader inthe Gre at Lakes. The zeb ramussel actually is a recent a ddition in a long history ofi nva d e rs , ra n ging from ra i n b ows m e l t , a l ew i fe, and lamprey tothe re c e n t ly introduced ru ffeand spiny water flea. Nowanother fo reign species hasb egun to spread throughout theinland wat e r ways. The ro u n dgo by ( N e ogobius melanosto -mu s ) was discove red in the St. Clair Rive r, the channel con-necting Lake Huron and LakeSt. Clair, in 1990. This speciescomes from the same area of the wo rld as the zeb ra mu s s e l( a round the Black and Caspian Seas). Pre s u m ably, t h eya rrived the same way as zeb ra mu s s e l s : in ballast water d i s ch a rged by transoceanic vessels. Although gobies belong to a fa m i ly of fish with awo rl dwide distri bution in both salt and fre s h wat e r, t h eyhad not been found in the Gre at Lakes prior to 1990. Asecond species, the tubenose go by ( P ro t e ro r h i nus mar -m o rat u s ), also ap p e a red in the St. Clair River in 1990; bu tthis species, wh i ch is endange red in its nat ive hab i t at , h a sremained uncommon. The more aggre s s ive, ro bust ro u n dgo by underwent a rapid dispersal and population ex p a n-sion in the St. Clair River and Lake St. Clair. In 1993 itb egan to spread to other wat e r way s , and the likelihood ofits spreading to wat e rsheds such as the Mississippi Rive rd ra i n age system has raised concerns over its potentiale ffects on North A m e rican nat ive species and ecosystems.Exotic species, s u ch as the round go by, h aved e s t royed and disrupted aquatic communities across then ation. The entry of another fo reign invader to the alre a dyabused Gre at Lakes env i ronment is an unwelcome add i t i o nto the plethora of other pro bl e m s , i n cluding hab i t at destru c-t i o n , ove r fi s h i n g, p o l l u t i o n , and loss of nat ive species. Range and Spread From 1990 to 1992 round gobies were found only in the areas adjacent to the St. Clair River: Lake St. Clairand in the first 2 km of the upper Detroit River. By 1993round gobies were found in the Grand River nearCleveland, Ohio (Lake Erie) and in the Grand CalumetRiver near Chicago, Illinois (Lake Michigan). In August1994, gobies became well established in the CentralBasin of Lake Erie. Also in 1994, gobies were found 12 miles east of the Grand Calumet River at HammondMarina and at South Haven, Michigan, on the east shoreof Lake Michigan. Because the Grand Calumet River isRound gobies invade North AmericaConfirmed Round Goby Sitings, July 1995Duluth-Superior Harbor (1995)lCalumet River (Dec.1993),Hammond Marina (1994), andCalumet Harbor (1994)Montrose Harbor (1995)lSouth Haven(1994)llDetroit River (1993) lSt.Clair River (Sept.1990) lGrand River (1993)lAshtabula River (1995)lconnected to the Mississippi River, round gobies nowhave access to America’s largest watershed. By 1995,they had spread to Duluth-Superior Harbor, in Duluth,Minnesota (Lake Superior), Montrose Harbor north ofChicago (Lake Michigan), and Ashtabula River in Ohio(Lake Erie).After they reach a new area, gobies are capable ofrapid population growth. Densities of gobies in rockyareas at Calumet Harbor already exceed 20 per squaremeter—equivalent to 20 fish in a space the size of a bathtub. The fish in this harbor range from 12 to 140 mm(0.5 to 5.5 inches) in length, and likely represent twoage groups. IdentificationRound gobies are bottom-dwelling fish that perch onrocks and other substrate. They can grow to 250 mm (10 inches) as adults. Gobies have large heads, soft bod-ies, and dorsal fins lacking spines; they slightly resemblelarge tadpoles (Figure 1). The gobies’unique feature istheir fused pelvic (bottom) fins, which form a suctorialdisk. In flowing water habitats, this suction disk aids inanchoring the fish to the substrate. Young round gobiesare a solid slate gray; larger individuals have blotches ofblack and brown over their bodies, and their dorsal finmay be tinged with green.Round gobies look similar to sculpins, a native,bottom-dwelling fish occasionally caught by anglers.Sculpins (Cottus bairdi and C. cognatus), also calledmuddlers or Miller’s thumb, are usually solid brown ormottled. Both sculpins and goby males can appear almostsolid black during spawning. Round gobies havea distinctive large black spot on the front dorsal fin; andsculpins often have a dark spot in the same location.Sculpins can most easily be distinguished from gobies by their separate pelvic fins (Figure 2).Figure 1Characteristics and HabitatRound gobies possess four characteristics thatmake them effective invaders.1. Round gobies are aggressive, pugnacious fish.They feed voraciously and may eat the eggsand fry of native fish such as sculpins, darters,and logperch. They will aggressively defendspawning sites in rocky habitats, therebyrestricting access of native species to primespawning areas.2 . Th ey have a we l l - d eveloped sensory system thatenhances their ability to detect water move m e n t .This allows them to feed in complete dark n e s s ,and gives them a major competitive adva n t ageover nat ive fish in the same hab i t at .3. They are robust and are able to survive underdegraded water quality conditions. This abilityand their propensity to swim into holes andother crevices probably allowed round gobies to enter and survive in the ballast water of ships.4. Round gobies spawn over a long period during thesummer months so they can take advantage of optimaltemperature and food conditions. Females mature at 1to 2 years and males mature at 3 to 4 years. Spawningcan occur frequently from April through September.E a ch female produces from 300 to 5,000 large (4 x 2.2 mm [0.16 x 0.09 inch]) eggs; these eggs ared eposited in nests on the tops or undersides of ro ck s , l og s ,or cans; they subsequently are guarded by the males.Round gobies pre fer a ro cky or gravel hab i t at; theyhide in crevices or active ly bu rrow into gravel when s t a rt l e d. In the Black and Caspian Seas, gobies ge n e ra l lyi n h abit the nears h o re are a , although they will migrate tod e eper water (up to 60 m [197 feet] depth) in winter. Th eyalso are found in rive rs and in slightly bra ckish wat e r. InE u ro p e, the diet of round gobies consists pri m a ri ly ofb iva l ves (clams and mussels) and large inve rt eb rat e s , bu tt h ey also eat fish egg s , small fi s h , and insect larva e. In theUnited Stat e s , studies have revealed that the diet of ro u n dgobies includes insect larvae and zeb ra mu s s e l s .Potential Impacts Gobies may compete successfully with native benthic fishsuch as sculpins and darters. Substantial reductions inlocal populations of sculpins already have been reportedfrom areas in which gobies have become established.Gobies may compete with sculpins for food or drive themfrom their preferred habitat and spawning area. In labora-tory experiments, gobies will eat darters and other smallfish. Of perhaps more concern is their predation on theeggs and fry of lake trout, which has been observed inlaboratory experiments. The reproduction of the lake troutin the Great Lakes is extremely limited.On the positive side, round gobies eat large quantitiesof zeb ra mu s s e l s , an invader that is causing an incre a s i n g lyl a rge number of pro blems because of its huge rep ro d u c t iveoutput. Zeb ra mussels are an important component of thego b i e s ’ diet in their nat ive ra n ge; and, in lab o rat o ry studiesin North A m e ri c a , a single round go by can eat up to 78zeb ra mussels a day.  Howeve r, it is unlike ly that go b i e salone will have a detectable impact on zeb ra mussels. Th eround go by is expected to be one of seve ral species( i n cluding duck s , c ray fi s h , d i s e a s e s , and other fish species)t h at eve n t u a l ly will reduce the abundance of zeb ra mu s s e l s .Gobies are preyed upon by seve ral sport fish species (e. g. ,smallmouth and ro ck bass, wa l l eye s , ye l l ow perch , a n db rown trout). Because the diet of round gobies consists pre-d o m i n at e ly of zeb ra mu s s e l s , t h e re may be a direct tra n s fe rof contaminants from gobies to sport fi s h .Gobies affect anglers in several ways. These fishaggressively take bait from hooks. Anglers in the Detroitarea have reported that, at times, they can catch only gob-ies when they are fishing for walleye.What can be done?Unfortunately, eliminating a species after it has becomeestablished usually is impossible. However, it may bepossible to slow the spread of these unwanted species intoour waterways. Ballast water exchange is one method ofreducing additional introductions of foreign organisms.Ballast dumping regulations within North Americanwaterways may help to prevent the spread of exoticspecies. Anglers and others can avoid accidentally spread-ing these species by dumping bait buckets only in areaswhere they were filled, and by not taking unusual animalshome to add to an aquarium. Note: there may be a temp-tation to take gobies for a home aquarium or home fishpond; however, transportation of gobies or other exoticspecies across state lines is illegal.What can you do?Learn to identify gobies (see illustration that indicatesfused pelvic [bottom] fins). To enable biologists to trackthe spread of round gobies, up-to-date information onnew sightings is needed. Your assistance is extremelyimportant. If you catch a round goby outside the areasnoted on the map indicating goby range, preserve the fisheither in alcohol (grocery store rubbing alcohol is fine) orby freezing it. Then contact your state Sea Grant office,fisheries management agency, or the Illinois NaturalHistory Survey (847/872-8676). Be prepared to describewhen and where you caught the fish (the name of the lakeor stream, and the nearest town). New sightings can beconfirmed only by identification of a captured fish. Verbalreports cannot be used because sculpins can be easilymistaken for gobies.For other publications,newsletter, conference, andworkshop announcements,or for advice from local experts ,contact the Sea Grant program or state naturalresources management officenearest you.Phone  numbers forthe Great Lakes Sea Grant pro-grams follow.Illinois-Indiana 217/333-9448Michigan 517/353-9568Minnesota 218/726-8712New York 800/285-2285Ohio 614/292-8949Wisconsin 608/263-3259Other Sea Grant programs and other agencies also havei n fo rmation ava i l a ble on this issue.Publishers and authors can be contacted at the addresseslisted here.Illinois-Indiana Sea Grant ProgramPurdue University1159 Forestry BuildingW. Lafayette, IN 47907-1159Administration765/494-3573 FAX 765/496-2422Communications217/333-9448FAX 217/333-2614For large orders of this publication, contact Ohio Sea Grant.Request OHSU-FS-065.Ohio Sea GrantCollege ProgramThe Ohio State University1314 Kinnear RoadColumbus, OH 43212-1194614/292-8949FAX 614/292-4364Michigan Sea GrantCollege ProgramUniversity of Michigan2200 Bonisteel BoulevardAnn Arbor, MI 48109-2099734/763-1437FAX 734/647-0768J. E.MarsdenAiken CenterSchool of Natural ResourcesUniversity of VermontBurlington, VT 05405802/656-0684FAX 802/656-8683emarsden@nature.snr.uvm.eduDavid J. JudeUniversity of MichiganCenter for Great Lakes and Aquatic Sciences2200 Bonisteel BoulevardAnn Arbor, MI 48109-2099734/763-3183FAX 734/747-2748djude@umich.eduSculpin — Sculpins have separate pelvic (bottom)fins. A dark spot on the dorsal fin is common.Round Goby —The distinctive feature of the round goby is its fused pelvic (bottom) fins.This fish can grow up to 10 inches in length, although 3- to 6-inch fish are more common.The smaller tubenose goby has two, rather distinct, tube-like projections from its head.Figure 2

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Round Gobies Invade North America

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