T recce 121 SHRIMP MATURATION AND SPAWNING Granvi 1 D. Treece TexasARM University, SeaGrant CollegeProgram 1716 Briarcrest, Suite 702 Bryan, Texas 77802 USA Tel: 09! 845 7527; Fax; 09! 845-7525;e-inail: gtreece.unix.tamu.edu ABSTRACT The lack of a reliablesupply of disease-resistantpostlarvae PL! continuesto contributeto the uncertainty, inefficiency,and economic loss facing shrimp farmers worldwide. Many of theworld's estimated 375 913 shrimp farms reiyheavily on wild stocks for broodand seed to stockponds! and many of the5777 hatcheries Rosenberry 1999! rely onready-to-spawn adult females from the oceans as a sourceof nauplii.As theshrimp aquaculture industry has matured, thenumber of farms relying on hatcheriesfor seedhas increased and hatcheries are adopting technology tocontrol the reproductiveprocess and to producegeneration after generauon of shrimpwithout totally relying on the wild populanons. Thistechnology offers independence from the unpredictable fluctuations in wild populations,accessibility to thesuperior non-indigenousspecies, improvement in performancethrough artificial selection, and somecontrol overthe diseases found in feral stocksthrough development of disease-resistantstrains. Thetechnology for controlof shrimpreproduction has not changed much since the most important breakthroughs in this areaoccurred more than 20 yr ago.The UnitedStates Department of Agricultute USDA! ShrimpFarming Consortiumhas made progress toward domesticating thewestern white shrimp Pen«ieus vannairiei, the newly proposed genusby Perezand Kensley998! is Liropenaet«s!,and has worked toward developing High Health, Geneticaliy Improved HHGI! animals for the industry. More progress is neededto stayahead of theshrimp virus problems plaguing theindustry. Problems with maleshrimp quality have beenovercome to someextent by using artificialinsemination techniques but, again, more research is needed, The technologyfor controlling shrimp reproductionis under constantrefinement by commercialand academic groups.Initial breakthroughsoccurred more than 65 yr agowhen a Japaneseresearcher published the first written accountof shrimpculture Hudinaga 1935!, The seine researcher spawned the kuruina shrimp and described the techniques in detail Hudinaga 1942!. Panouse 943! describedshrimp eyestalk ablation, but it wasnot usedin commercial shrimp inaturationuntil theearly I 970s.A few advancedfarms were familiar with the techniques, but there was reluctance to shareinformation. For many years, the industry generally preferred wild-caught PL overhatchery-reared PL,but with the adventof shrimpviruses like theWhite Spot Syndrome Virus WSSV!and evidence of measuredgrowth from capuvestocks, the industry is graduallybecoming more dependent on captive stocks, Disease-resistant, hatchery-reared animalsare becoming more popular for pond stocking, Practicing the HHGI concept involves strict biosecuiity measures at thehatchery and farin tocontrol disease which generally involve limiting access and maintaining strict quarantine procedures.Pond growout comparisonshave been made with PL from different sources,and it is documentedthat domesticationandthe HHGI concept with added biosecurity measures practiced! have benefits over wild-caught stocks. TheUSDA funded US MarineShrimp Farming Program, The Oceanic Institute, and a numberof otherorganizations havemade progress in domesticatingand selecliiig faster-growing, disease-resistant families of shrimpand have brought themforth in their breedingprograms. Several private coinpanies are now utilizingthe offspringfrom this workto producefuture generationsof shrimpfor the aquacultureindustry Dr, JamesWyban, Hawaii, personalcommunication, http://www.hihealthshrimp.corn!. Several research groups have selected animals through numerous generations that do not requireablalion and the resulting animals selected spawn without ablation Dr. RobertShleser, Hawaii, personal communication!,Through selective breeding, virus-resistant strains of P. srylirostriscalled the Super Shrimp were developedin Venezuelawithout eyestalk ablation Chris Howell, Venezuela,personal communication! and this has assistedMexico to reestablishitself as oneof the topproducing shrimp mariculture countries in LatinAmerica. INTRODUCTION j aponicusfemales and reared the resultinglarvae Maturation - ResearchHistory to subadults Hudinaga 1942!, The capture of wild Dr. MotosakuFujinaga Hudinaga1935! females with mature ovaries for immediate made someof the most important contributions spawningin captivity, known as "sourcing", was to the development of shrimp culture when he first the only method known and practiced for inducing accomplished captive spawning of mature P. penaeidfemales to spawn in captivity until the 122 UJNR Technical Report No. 28 early1970s. As discussedearlier, shrimp eyestalk Lawrence992!, In the 1990s,shrimp viruses ablation was not used in commercial shritnp forced the industry to rely less on feral maturation until the early 1970s. populations,adopt biosecurity measures, and look Thesourcing of gravidfemale shrimp is more closely at perfecting domesticationof still widelypracticed today in manycountries with species.The shrimp aquacultureindustry has an abundantsupply of wild brood in nearby followedsimilar steps taken earlier by thepoultry waters.In the past,Japan had a totaloutput of and swine industries in an attempt to control 600 to 700 million PL shrimp annually using diseases. sourcedfemale P.japonicus. About 80% were used to restock coastal fisheries and the rest were Maturation aud SpawningResearch used in commercial culture Liao and Chao 1983!. Highlightsin the United States Sourcing,or obtainingready-to-spawn females Johnsonand Fielding 956! reportedthe from the wild, has been used worldwide for first successfulmaturation and spawning with experimentaland commercial culture of numerous fertilizedeggs! of P.setiferus in theUS, butthis otherspecies. This is particularlytrue in Southeast was in ponds.In 1959,the National Marine Asiawhere a singleP. rnonodon female can sell FisheriesService NMFS! hadbegun to adoptand for US$500-$2,000or more. Sourcing,however, use a modification of the Japanese culture limits culturists to the use of indigenousspecies techniqueto assistwith closingthe cycleof thatmay or maynot be the best, or evena suitable, importantspecies for theshrimp fishery in Texas. culture speciesand is dependenton seasonal Cummings961! describedmaturation and availability, migratory movements,weather, spawningin thepink shrimpP. duorarurn,Dr. naturalrhythms, and diseases in feralpopulations. Fujinagavisited the NMFS Laboratoryin Effortsto inducepenaeid reproduction in captivity Galveston,Texas, in 1963 with the intention of continuedso that a consistent,reliable sourceof scoutingthe area for a shrimpmariculture facility. PL seedstock could be obtained to support Instead,a facility waslater built in the stateof commercialculture operations and establish the Florida. Soineof the other researchpublications basis for genetic selectionto develop ideal from the NMFS lab were Brown and Patlen domesticstocks with stronggrowth and survival 974!, Brownet al. 979, 1980!,and Duronslet characteristics resistance to diseases!.Annie et al. 975!, TheGalveston Laboratory, serving Laubier-Bonichon and L. Laubier at the Centre asan important demonstration and training center Oceanologiquede Bretagnein Brest, France, for maturation-hatcherybiologists worldwide, developedthe "Laiibier method" of shrimp continued to refine maturation, hatching and maturation which involves maturatio~ of P, larval-rearingmethods throughout the 1970s. The japonicususing temperature and photoperiod methodsutilized by theNMFS researchers are still manipulation,without ablation or theremoval of widely knownas the intensivemethod or "the oneeye Laubier-Bonichonand Laubier 1976; GalvestonLaboratory Technique" Klima 1978; Laubier-Bonichon 1978!, The Laubier method McVey 1983! sometimesreferred to as the workedfor P j aponicuson a smallscale but was clearwatermethod. The methodsused today are not dependablefor commercialuse. The French basicallymodifications of this intensive method, made other important advancesin shrimp andmethods developed in Asiaand other parts of maturation Aquacop 1977a, 1977b, 1979, 1984!. the world, NMFS continuedresearch and training Additionally, the SoutheastAsian Fisheries at the Galvestonlaboratory in the early 1980s, DevelopmentCenter SEAFDEC! in the andlater under Texas AsrM University Lawrence Philippinesmade very important contributions to et al. 1980!the research continued along similar our presentknowledge of shrimp maturation lines. Similar research occurred at Texas AkM Primavera1978, 1979; Primavera et al. 1980!. University TAMU! maincampus Chamberlain Good literature reviews of maturation and and Gervais 1984! and the TAMU Texas reproductionin penaeidshrimp were done by AgriculturalExperiment Station labs in Corpus Primavera985!, Harrison990!, andBray and Christi andPort Aransas, Texas, Other institutions T recce 123 like The OceanicInstitute in Hawaii Oyama et vannarnei spawners from the Ecuadorian coast al. 1988! worked with shrimp maturation and might contradict the above Roeland Wouters, spawning. Since the late 1980s, research and CENAIM/ESPOL, Ecuador, The following developmentby the US Marine Shrimp Farming equationwas calculatedfrom 612 spawns some Program has contributed to the successof the US of themwere repeat spawns! from spawnerswith shrimp aquacultureindustry. Commercialtrials weightsranging from 27 to 80 g: