Pete Alexander, EBRPD
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againbeavailabletoanadromousfish,andwecanrestockasnecIt’s not that mosquito fish are deficient at their task, Miller essary with our native rainbows,” Leidy says. says.They do a fine job of gobbling mosquito larvae, and they Happily,nativeEastBayrainbowtrout — non-anadromous arefecundintheextreme.Plantsomemosquitofishinapond variants of the steelhead — are still relatively common, but orslough;they’llreproducewithgreatrapidity,andmosquitoes nolesspreciousfortheirabundance.Alexanderdeemsthem willdeclineproportionately.Theproblemisthatthey’lleatmore “genetictreasures.”“Peopleoriginallylearnedaboutrainbow than mosquito larvae and eggs. They’ll also chow down on endangered red-legged frog and tiger salamander eggs. trout from our East Bay trout,” Alexander says. “We have evi“That has raised some concerns, so we’re looking at native dencethattheywerefirstgiventhename‘rainbow’basedonfish fish as alternatives,”Miller says.“I doubt we’ll ever move comtaken from an East Bay creek (San Leandro) and described in pletelyawayfrommosquitofish,buthavingsomeoptionscould 1855.Notlongafter,rainbowtroutweretransportedtotemperate regions throughout the world.” help with native fish restoration.” MillerfirsttriedSacramentoperchasamosquitofishsubstiDams have contributed to the decline of the East Bay’s steelhead — butparadoxically, tute, but that proved a no go. thereservoirstheseimpediments “They were hard to raise,” he have created have aided in the observes. Today, he’s experimentingwithSacramentoblackpreservationofnativerainbows: Instead of migrating to the fish,Californiaroach,andhitch, oceanfromtheirnatalstreams, anotherheat-tolerantCalifornia native. He’s rearing the fish in rainbows migrate to the reservoirs that back up behind the morethan20swimmingpools, dams.Theretheyfatten,returnsome located on foreclosed properties. That achieves the ing to the creeks that enter the reservoirs to spawn. dual purpose of eliminating mosquitoesfromwatersources San Antonio Reservoir, a that would otherwise teem few miles southeast of Sunol Regional Wilderness, is espewith larvae and contributing ciallyfinerainbowhabitat.Built to research in native fish in 1964 by the City of San Franpropagation. Biologists from the East Bay Regional Park District conducting a wildlife survey at So how’s it going?“The Saccisco,itstorescold,clean,highly Sindicich Lagoon in Briones Regional Park. ramentoblackfisharefairlyeasy oxygenated Sierra water from tospawnandraise,sowehavesomehopesforthem,”Millersays. theHetchHetchyaqueduct.LikeotherEastBayreservoirsthat containnativerainbows — CalaverasandUpperSanLeandro “We collected some hitch under a Department of Fish and reservoirs — SanAntonioisclosedtoangling.Therolling,oakWildlife permit two years ago, we’ve raised them to maturity, studdeduplandsthatsurroundthereservoirarewellvegetated; and we’re trying to get them to spawn.We’ve seen spawning erosionisminimal,andthelakedoesn’tsufferthesedimentation activityandafewlarvae,sowe’regettingclose.Andwe’repretty problemsthatblighttroutpopulationselsewhere.“SanAntonio optimisticabouttheCaliforniaroach.Mosquitofishtypically essentially serves as the ocean for these fish,”Leidy says,“and [stop eating] at lower temperatures, but California roach just they’ve adapted well.” keep on eating. We think that could make them valuable for Whilethefisharegeneticallysimilartotheirancestorsthat late season abatement — say, at duck clubs in the fall.” Miller’sworkpointstothekindofflexibilityandinnovative went to sea, they differ from steelhead in one significant way: thinking needed to maintain the East Bay’s rich complex of size. In the ocean, steelhead graze for years on rich shoals of nativefreshwaterfish.Inlightofthechallenges — everything krillandforagefish.Returningsteelheadspawnerscanoccasionfromongoingurbandevelopmenttoclimatechange — itwon’t allyreachweightsof20poundsormore.“Amature,nativerainbeaneasymission.Butthereareopportunities,saysMoyle,and bowtroutbycomparisonprettymuchtopsoutatthreetofour it’s incumbent on both scientists and citizens to seize them. pounds,”saysAlexander.“Butforalandlockedrainbow,that’sa very respectable fish.” “The big thing we have going for us are the East Bay parks andtheutilitydistrictlands,”saysMoyle.“They’regivingusthe Given the ongoing challenges faced by the East Bay’s abilitytopreserveandevenenhancemanyofthesefishpopulanative fish, biologists are always looking for opportunities to tions—andthey’realsogivingusthechancetoshowthepublic thatthesefishexist,thatthey’resomethingworthsaving.” stabilize existing populations and establish new ones. At the Contra Costa Mosquito Abatement District, biologist Chris GlenMartin,formerenvironmentalreporterfortheSanFranciscoChronicle, Miller is testing native fish as substitutes for exotic mosquito writesonnaturalresourceissuesforvariouspublications.Hislatestbook,Game fish,currentlythepreferredmeansforcontrollingmosquitoes Changer:AnimalRightsandtheFateofAfrica’sWildlife,waspublished in California. by UC Press in March 2012. bay nature
october–december 2013