Endangered Species Protection Program (ESPP) The deltasmeltisa The U.S.Environmental Hypomes Endangered species Program (ESPP)willhelp Endangered SpeciesProtection Protection Agency’s(EPA) not jeopardizethesurvivalof becoming extinct. plants andanimalsthatare population numbersareso in immediatedangerof ensure thatpesticideusedoes endangered inthefuture. are plantsandanimalswhose listed species. low thattheymaybecome species us transpacificuss . Threatenedspecies o source: B. Moose Pet B.Moose Photo source: erson/USFWS Digital Library Library Digital erson/USFWS are threatened Office ofPesticide Programs (7507P) Endangered Spec Endangered tail. pose teeth ontheupperandlowerjaws.Asmall, appear large.Itsrelatively smallmouthhaslittle,pointed its delicate,slenderbodyappearsnearlytransparent. Itseyes inches inlength.Except forthesteel-bluesheenon itssides, Range Appearance Critical Habitat Status Description andEcology Habitat These highdensities occurwhenthemixing zone occupies a limited. Larvae require highdensitiesofmicrozooplankton. usual speciesrichness(microzooplankton) ofthemixingzone may befasterandmoreturbulent,shoalsabsent,the and limitedtothedeeperriver channels wherethecurrent into theriver channels.Therethemixing zone is compressed freshwater downstream,themixingzone isdrawn upstream drought andriver water diversions reducetheout the mixingzone (wherethesaltandfreshwater meet).As locations ofdeltasmeltaretiedtothefreshwater sideof water makes upmorethan1/3ofthetotalwater. The (saltwater tolerant) species,itisseldomfoundwheresea arises fromthefactthatwhiledeltasmeltisaeuryhaline in theDelta. abundance hasshiftedeasttotheSacramento River channel increasing water diversions anddrought,thecenterofspecies upper SuisunBay andtheMontezuma Slough.Asaresultof Rivers. Whenout extent ofwater out Locations aredependantuponstageinthelifecycle and and upstreamintheSanJoaquinRiver toaboutMossdale. then upstreamintheSacramento River toaboutIsleton were foundfromSuisunBay, easttotheDeltaarea,and San JoaquinestuaryinCalifornia.Historically, populations Delta Smelt fin) sitsatopthebackbetweendorsal DeltasmeltarefoundonlyintheSacramento- Threatened,listedMarch5,1993. This shiftinthespeciescenterofabundance Thedeltasmelttypicallygrowsto2.4–2.8 flow was greater, deltasmeltcongregatedin flow fromtheSacramento andSanJoaquin Designated December19,1994. Hypomes us transpacificus fl eshy fin andthe fl ow of ow fi n (adi- n http://www.epa.gov/espp/ U.S. EnvironmentalProtectionAgency area ofChinaandJapan, af larvae, andconsistprimarilyofanative copepod, The preyofthedeltasmeltaresmallcrustaceansandinsect slows downwhiletheirbodiesreadyforreproduction. several monthsthegrowthrate ofthedeltasmeltjuveniles This definesthedeltasmeltasanannualspecies.For thenext adults suggeststheymay not live much beyond spawning. 2.0 inchesinlength.At thistimethemarked absence ofolder and theirowngrowthrapid. ByAugustthejuveniles are1.6– upstream ofthemixingzone. Therepreyshouldbeabundant water columnandbewhisked downstreamto withinorjust the 0.6–0.7inchlonglarvae areabletorise higherinthe and othermicroscopicprey. Aftertheswimbladderdevelops, above thebottomwheretheyareabletofeedonrotifers Initially thelarvae have anoilglobulethatbuoys themjust another 4–5days. temperatures eggshatchin9–14days. Feeding beginsin roots, andsubmergedvegetation orbranches. Withoptimum Eggs sinktothebottomandadhererocks,gravel, tree the upperDelta.Eachfemalebroadcasts1,200–2,600eggs. occurs insloughsandshallow, edge-waters ofchannelsin to eclipsetheseasonfromMarchmid-May. Spawning can occurfromJanuarythroughJuly, lowout Reproduction andLifeCycle inability ofsunlighttopenetrate water depths. the rivers anddelta,wherefoodproductionislimitedbythe and theirlarvae upstreaminthedeep, narrowchannelsof depths lessthan13feet.Lowout sloughs, wetlandedges,andsuitablespawningsubstrate at large geographic areasuchasSuisunBay, whichhasshoals, eliminated much ofthebenthiccommunity of SuisunBay, the in SuisunBay in1986.Afteramulti-year droughtthat Another exotic species,theoverbite clam,was discovered exotic species,thefullimpactofitspresence isunknown. replacing fi nis . Recently anexotic copepodspeciesfromtheYangtze ies E. af fi nis . Whiledeltasmeltappearto consumethis Pseudodiaptomus forbesi Facts flows keep adultdeltasmelt Whilespawning fl February 2010 ow tends ow Eurytemora , hasbeen Delta Smelt

population of overbite clams spread. Its numbers and their Delta Smelt Information Sources filtration rate can impact the phytoplankton population and, as a result, the overall food web. Striped bass, white catfish, Primary Reference Beacham, Walton, Castronova, and black crappies prey upon delta smelt. Frank F., and Sessine, Suzanne (eds.), 2001. Beacham’s Guide to the Endangered Species of North America, Gale While populations of delta smelt have fluctuated from year to Group, New York. Vol. 2, pp. 908–912. Phot o of the San Joaquin-Sacramento River Delta courtes y of Dave Polaschek. year, drought from 1987 to 1992 severely impacted the delta smelt numbers. A rebound in the population the following Listing Notice U.S. Fish and Wildlife Service, 1993. year was attributed to a wetter winter and spring. Since then Federal Register 58, No. 42, pp. 12854-12864, March 5, the numbers, of what once was one of the most common 1993. http://ecos.fws.gov/docs/federal_register/fr2235.pdf pelagic fish in the Sacramento–San Joaquin estuary, have Critical Habitat Designation U.S. Fish and Wildlife dropped significantly. Critical habitat was designated for Service, 1994. Federal Register 59 No. 242, pp. 65256- this species on December 19, 1994. However, by 2005 the 65279, December 19, 1994. http://ecos.fws.gov/docs/ population of delta smelt was perhaps as little as 2.4% of the federal_register/fr2751.pdf estimated population in 1993 when the delta smelt was listed Recovery Plan U.S. Fish and Wildlife as “threatened.” Service. 1996. Sacramento_San Joaquin Delta Recovery Plan The U.S. Fish and Wildlife Service (FWS) Native Fishes Recovery Plan. U.S. Fish and Wildlife developed a recovery plan for the delta smelt in 1996. Service, Pacific Region, Portland, Oregon. 195 pp. Recovery plans outline reasonable actions that FWS http://ecos.fws.gov/docs/recovery_plan/961126.pdf believes are required to recover or protect listed species. FWS prepares recovery plans, sometimes with the assistance Phot o of Suisun Bay courtes y of Mike Huisking. of recovery teams, contractors, state agencies, and others. Recovery plans do not necessarily represent the views nor the official positions or approvals of any individuals or agencies, other than FWS, involved in the plan formulation. Approved recovery plans are subject to modification as dictated by new findings, changes in species’ status, and the completion of recovery tasks.

Native copepod Eurytemora affi nis (magnifi ed, left), and introduced Pseudodiaptomus forbesi (right), prey of the delta smelt. Bot h images courtes y of Jeff ery R. Cordell, Copepod Gallery, University of Washington.