©CopyrightJASSS

FrancescoPizzitutti,CarlosF.MenaandStephenJ.Walsh(2014)

ModellingTourismintheGalapagosIslands:AnAgent-BasedModelApproach

JournalofArtificialSocietiesandSocialSimulation 17(1)14<http://jasss.soc.surrey.ac.uk/17/1/14.html>

Received:29-Jan-2013Accepted:08-Sep-2013Published:31-Jan-2014

Abstract

CurrentlytourismisthemaindriverofchangeintheGalapagosIslands,affectingthesocial,terrestrial,andmarinesub-systems.Tourismalsohasdirectandindirectconsequencesfortheuniquearchipelago'snaturalhabitatsandforthehumanwell-being.DescribingthemechanismsthatdriveandaffectmostthetourismdevelopmentinGalapagosisapreliminaryconditiontodevelopingabetterunderstandingoftheinteractionstructureoffactorsthatshapetheGalapagosarchipelagoasasocial-ecologicalcomplexsystem.Inthispaper,wepresentafirstattempttorepresentthetouristicmarketinGalapagostroughanAgentBasedModel(ABM)oftouristicactivity,focusingontouristicoffers,reservations,andtouristicactivities.Themodelisbasedonanindividual-basedrepresentationoftourists'consumptionpreferencesandtouristicaccommodationoffersintheGalapagosIslands.TouristagentsarecreatedtomimictherealworldbyassigningaveragecharacteristicsofindividualswhovisittheGalapagosArchipelagoofEcuador.Theaccommodationoffers(i.e.,hotelsandcruises)aregeneratedinaccordancewithactualconditionsderivedfromdatacollectedthroughfieldsurveys.Themodelincludesamarketagentthatcanchangetheprices,createanddeleteaccommodationoffersfollowinganevolutionaryalgorithm.Wecarriedoutpreliminarysimulationsthatshowacloseagreementbetweenrealworlddataandmodeloutputs.Furthermoreweusedthemodeltogeneratethree"whatif"scenariosinordertostudyhowemergentpatternsinthetouristicmarketinGalapagosareaffectedbychangesinthearchipelagoenvironment.Inthiswayweillustratehowthemodelcanbeusedasausefultooltohelppublicpolicymakerstoexploretheconsequencesoftheirdecisions.

Keywords:SpatialAgentBasedModelandSimulation,GalapagosIslands,TouristDestinationDynamics

Introduction

1.1 Overthelastfewdecades,tourismintheGalapagosIslands,likeinmostintactandpristinebiodiversitysitesaroundtheworld,hasexperiencedanexplosivegrowthinthenumberofinternationalvisitorsandinthedevelopmentofinfrastructuretosupporttheconsumptiveneedsoftourists(Epler2007).ThisremarkabledevelopmentisinducingchangesinnearlyeveryaspectoflifeintheGalapagosIslands(Watkins&Cruz2007).Forinstance,localcommunitiesintheGalapagoshaveexperiencedarapidincreaseintheresidentialpopulationcausedbythemigrationofEcuadoriansfromthemainlandinsearchofjobsinthelucrativetourismindustry,withnegativeimplicationsfortheuniqueandfragilenaturalenvironmentofthisWorldHeritageSite(Bensted-Smith1999;Truemanetal.2010).Migrantsarebeing"pushed"fromtheEcuadorianmainlandbyagenerallypooreconomyandrelativelylowwages,and"pulled"bythehigherpayingjobsintourismthataremandatedbyEcuadorianlawandaccentuatedbytherobustgrowthintheisland'stourismindustry.Thedevelopmentofthetouristicmarket,inspiteoftheeffortscarriedoutbypublicandprivateconservationinstitutions(ParqueNacionalGalápagos2007),seemstobeoccurringinarelativelyuncontrolledandconflictivemanner.Theperceptionisthatalltheattemptstoregulatetherapidtourismexpansionhavebeenconductedinanintermittentandunconnectedway,proposingsolutionstoacutesocialandecologicalcriseswithoutalong-termvisionorstrategicplan(González,Montes,Rodríguez,&Tapia2008).Attemptstoregulatetourismandtocreateasustainableislandeconomythatexplicitlylinkstonaturehavebeenfleetingandepisodic.

Figure1.Thestudyarea

1.2 TheGalapagosarchipelago(seeFigure1foramapofthearchipelago),viewedasanecotourismdestination,isanemblematiccaseofthechallengesofacoupledhuman-naturalsystem(CHANS)(Liuetal.2007)inwhichanaturalresource(theGalapagosislandecosystem)isexploitedbyhumans(tourists)producingfeedbackmechanismsthatinfluencesocial-ecologicalinteractions,dynamics,andtrajectories.Endogenousfactorsandexogenousforcesinteractincomplexwaystoshapeandreshapehuman-environmentinteractions.Incoupledhuman-naturalsystems,atthebeginningofthelinkingprocess,the

http://jasss.soc.surrey.ac.uk/17/1/14.html 1 15/10/2015

exploitationincreasesexponentially.Thenaperiodofdegradationofthenaturalresourcequalityandavailabilityisobserved,withasubsequentdeclineinecosystemgoodsandservices,potentiallyleadingtoradicalchangesoracollapseoftheexploitiveactivities.ThissituationcanleadtoanevolutionoftouristdestinationsthathasbeenextensivelydescribedbyPlog(1974)andButler(1980).Typically,CHANSaredifficulttostudybecauseoftheirnon-linearitycharacteristics,multiplespace-timescales,complexfeedbackmechanisms,anduniquelocalcontextsthatarelinkedtoforcesofglobalization.Thisfrequentlymakesitdifficulttoexportprocessunderstandingfromoneplace-basedstudytoanother(Ostrom2007).Obviously,fromamanagementanddecision-makingpointofview,themainchallengeofCHANSissustainability,thatis,theattainmentoftheequilibriumbetweenprolongedandcontinuoushumanactivitiesandthewell-beingofthenaturalenvironment.UnderstandingwhysomesystemsaresustainableandotherscollapseisthemainpurposeoftheCHANSperspective(Ostrom2009).

1.3 Withouttourism,theGalapagoswouldremainarelativelypristine,unique,andbiodiversity-richislandarchipelagoinwhichagricultureinthehighlandsandfishingalongthecoastwouldcontinuetobetheprimaryhouseholdlivelihoods,nowsubsumedbytourism.Inhabitedbyfarfewerpeople,thehumandimensionwouldlikelyberelativelywellintegratedintotheoceanicenvironmentsettingoftheGalapagos,firstencounteredbytouristsarrivingintheGalapagosinthe1950s(Epler2007).Butevenbeforethearrivalofinternationaltourists,theGalapagoswasexploitedforitsnaturalresourcesofbothterrestrialandmarinespecies.Determiningthehistoricallegacyofexploitation,thespace-timelagsofimportantendogenousandexogenousfactors,andtheadaptivecapacityofthetourismindustry,aswellaslocalorinternationalactors,whocollectivelyshapesocial-ecologicalinteractions(Baggio2008)isakeystepinunderstandingthedynamicsandtrajectoriesofthearchipelagoasitreactsandadjuststotheconsumptivedemandsofaburgeoningtourismindustry.

1.4 Inthelastdecades,AgentBasedModels(ABMs)wereincreasinglyusedinawiderangeofstudies(Grimmetal.2005).InABMs,agentsareintegratedinacomputer-basedmodel.Everyagentcanrepresentindividualssuchastouristsorgroupsofindividualssuchasinstitutions.Toeverysingleagent,asetofbehavioralrulesareassociatedthatpermitagent-to-agentandagent-to-environmentinteractionstobesimulated.IntheABMsetting,itispossibletostrategicallyandcontrollablychangetheagents'featurestobuildasetof"whatif"scenarios,studytheresultingchangesinthesimulationsoutputandexaminesystembehaviorandagentlearning.ThisfinalaspectofABMscanbeusedtoanalyzeandmanagetouristicdestinations,butrarelyhaveABMsbeenusedwithsuchanobjectiveinmind.Indeed,despitefewpreliminaryworks(JohnsonandSieber2011;BalbiandGiupponi2010;Yin2007;CecchiniandTrunfio2007),noattempthasbeenmadetobuildacomputationalmodelofatouristicdestinationthatintegratestheeconomic,social,environmentalandpsychologicalfeaturesofalltheactorsinvolved.

1.5 ThispaperrepresentsafirststeptowardsthebuildingofanABMofthetourismmarketintheGalapagosIslandsandinwidertermstowardsthebuildingofanABMofatouristdestination.Theaimofthisstudyistoidentify,amongthevastnumberofmicroscopic,individualbasedelementthatcreate,throughacomplexnetworkofinteractionsthetourismmarketsysteminGalapagos,alimitedsetoffeaturesthatcanbeusedtoeffectivelybuildamodelabletoreproducesomeoftheemergentpatternsoftherealworldsystem.Theresultingmodel,aswedescribeinthelastsectionofthispaper,couldbeusedtobuilddifferentkindof"whatif"scenariostotesttheimpactofpossibleinterventionsandpolicies.FromthispointofviewthemodelthatwepresentcanbeusedbypublicpolicymakersliketheGalapagosNationalParkadministratorsasatooltoevaluatetheconsequencesoftheirdecision.

1.6 Thepaperisdividedasfollows:inthefirstpart,aspectsofthetourismmarketintheGalapagosaredescribedthatarerelevanttothederivedmodel,inthesecondpart,theABMisdescribed,andinthethirdpart,resultsfromsimulationarepresentedanddiscussed.

TheGalapagosTourismMarket:Uncontrolled,ExplosiveExpansion

2.1 Asmentionedabove,tourisminGalapagoshasexperiencedanexplosivegrowthinthelastfewdecades.AreviewoftheavailabledatafromtheGalapagosNationalPark(ParqueNacionalGalápagos2012)showsthattouristarrivalsinGalapagosgrewexponentiallyfrom1995–2011,withanaverageannualgrowthrateofapproximately9%(seeFigure2).

Figure2.NumberoftouristsvisitingGalapagosfrom1975to2011(Source:GalapagosNationalPark)

2.2 FollowingButler(1980),therepresentationofthelife-cycleofatouristicdestinationcanbebasedonaSshapedcurvedescribingsixstagesthatthedestinationwouldgothroughastourismdevelops:exploration,involvement,developmentshowinganexponentialgrowth,consolidation,stagnationandtheendingwitheitherrejuvenationordecline.AsshowedinFigure2,theexpansionoftourisminGalapagosisstillinthe"development"phase,notyetapproachingthe"stagnation"phase.TheGalapagostouristicmarketevolutionprocessinthelastfewyearsfollowedthesamegeneralpatternofgrowthseenontheEcuadorianmainlandandintheneighboringcountriesofPeruandBolivia(WorldTourismOrganization2006).AnothercharacteristicoftheGalapagosIslandsisthatthearchipelagoisrelativelyremoteandisolated,factorgenerallyresponsibleforitshighnaturalendemismthatinturnisthesourceoftheattractionofinternationaltourism.Also,thearchipelagogeographyremotenessresultsinageneraldisconnectionfromtheusualtouristicroutes,creatingtheneedforahightransportationinvestmentintheinfrastructureintheislandsbylocalandregionalgovernmentsandhighercostsofvisitingtouristsincomparisontoothercompetingtouristicdestinations.Consequently,thenormaltouristrarelyvisitsGalapagosmorethanonce,oftenseeingthearchipelagoasa"bucketlist"destination.ThesurveyconductedbytheGalapagosTourism

http://jasss.soc.surrey.ac.uk/17/1/14.html 2 15/10/2015

MonitoringCenteroftheEcuadorianMinistryofTourismin2011(ObservatoriodeTurismoGalapagos2011)pointsoutthat92.66%oftheinterviewedtouristvisitedGalapagosforthefirsttime.ThisimpliesthatalmosteverytouristicexperienceinGalapagosisafirsttimeexperience,probablynevertoberepeated.AnotherimportantaspectoftheGalapagostouristicmarketisthatvisitorstypicallybookanaccommodationofferbasedonthechoiceofsecond-handsourcessuchasinternationaltravelagenciesand/orcompaniesthatadvertiseontheinternet.TheseorganizationspresenttotheinternationaltourismmarkettheGalapagosasapristine,natural,anduniquearchipelago.Thetouristacceptsthisrepresentationandthecorrespondingofferswithoutadirectknowledgeofwhathe/sheisactuallybuying.Weinfusetheseconditionsinourmodelbyrelyinguponparametersthatcharacterizetouristicoffers,suchas,whetherthehotelisnearorfarfromabeachorthecategoryofacruiseboat.

2.3 ThetourismexperiencesinGalapagoscanbedividedintotwomainsegments:theland-basedtourismandtheboat-basedtourism.TouristsreservingacruisetoexploretheGalapagosIslandsaredefinedas"boat-based,"because,ingeneral,theyspendmostofthetimeoftheirtouristicexperienceonboard–sleeping,dinning,anddisembarkingforshortislandactivities.Thistypeoftouristsisperceivedbyresidentsasnotcontributingtothelocaleconomy(Epler2007),asfundstendtosupportnationalandinternationalboatcompaniesandlargetouringorganizations.Land-basedtouristsaretouriststhatspendallormostoftheirtouristicexperienceinlocalcommunities,sleepinginhotels,arrangingtouristactivitieswithlocalvendors,andeatingattheirhotelsorinlocalrestaurantsandtheyareperceivedbylocalpeopleasmorereliantonlocalproducts,workers,andservices.Thedifferencebetweenlandandboat-basedtouristsishighlyrelevantfromthepointofviewoftheimpactonthesocial,terrestrial,andmarinesub-systems,asland-basedtourismimpliesgreaterurbandevelopmentandsupportinginfrastructure,useofpublictransportationandprivatevehicles,increasedrateofexoticspeciesintroductionasaconsequenceoftheimportationofmostfoodandproductsfromthemainland,depletionofdrinkingwaterreserves,consumptionofenergy,generationofwaste,andtheneedsofanenhancedwaterandsanitationsystemsthroughoutthearchipelago.Overthelast20–30years,boat-basedtourismdominated,buttoday,thenumbersofland-andboat-basedtouristsarenearlyequal.

2.4 ToabetterunderstandingoftheGalapagostouristsystemenvironment,itshouldbenotedthatintheGalapagos,onlyfourislandsarepopulatedandthusequippedwithtouristiclandinfrastructures:SanCristobal,SantaCruz,Isabela,andFloreana(seeFigure1).SanCristobalishometotheprovincialgovernment,SantaCruzisthehuboftourismwhileIsabelaistheepicenteroftheconflictsbetweenresourceconservationandeconomicdevelopment.Floreanahasthefewestresidentsandtourists,constrainedbythelackofavailabilityfreshwaterandthelimitedsupportinfrastructurefortourism.OnlySantaCruzandSanCristobalhostairportsthatdirectlyconnecttheseislandswiththeEcuadorianmainland.

2.5 ThemodelwepresentinthispaperreproducestheseGalapagostouristmarketfeaturestorepresentthereservationprocessaswewillshowinthenextsections.

TheAgentBasedModel

3.1 ThisABMisdescribedfollowingthe"'Overview–Designconcepts-Details"(ODD)protocolproposedbyGrimmetal.( 2006;2010).

3.2 Shortly,themodelisdesignedasfollows:whenatouristagentiscreated,theagentestablishesasortedlistofalltheavailableaccommodationoffersbasedupontheagentindividualcharacteristicsandthefeaturesoftheallavailableaccommodationoffers.Scrollingthroughthesortedlistofaccommodationoffers,thetouristagentbooksthefirstofferthatisaccessiblebypricerangeandbedsavailability.Accordingtothetouristagent'sdecisions,theaccommodationofferscanaccumulateaneconomicprofitforthetouristicprovideragent.Theoffersthataccumulateaprofitfasterareduplicatedwiththesubsequentcreationofanewindependentaccommodationoffer.Theduplicationprocessisimplementedincludingsmallchanges(mutations)inthepackagingoftheparentduplicatedaccommodationoffer,therebycreatinganevolutionaryselectionprocesssimilartotheevolutionaryalgorithmsusedinmetaheuristicoptimizationproblems(Gen2010).

3.3 Furthermore,apartialrepresentationoftheGalapagosgeographicalspaceisincludedinthemodeltorepresentthecostsintimeandmoneythatarerequiredforatouristagenttomovefromoneislandtoanother.Inthisway,itispossibletoincludethemovementsoftouristsbetweenislandstotakeincountthefactthateverytouristwantstomaximizethenumberoftouristicattractionsvisited,travelingfromislandtoislandminimizingthetransportationcostintimeandmoney.

3.4 Inwhatfollows,wedefineanaccommodationofferasatouristicofferthatincludesaccommodationamongtheirservices.Wedefineahotelasanykindofland-basedaccommodation(e.g.,hotels,hostals,resorts),andcruisesasanykindofboat-basedaccommodation(cruiseboats,yachtsandothers).Moreover,weusetheexpression"touristicattraction"toindicateallthepossibletouristicactivitiestowhichthetouristcouldaccessduringhis/herstayintheGalapagosIslands.Amongtouristicattractions,weincludedaytours,visitstointerestingplaces,watersports,trekkingtrails,snorkelingsites,useofbeaches,andothers.

Overview

Purpose

3.5 Thepurposeofthemodelistoexaminethetourists'decision-makingprocessesthatrelyuponthecharacteristicsoftheaccommodationoffersinfrastructure,uponthetourist'sindividualpreferences,aswellasuponthespatialconfigurationcharacteristicsoftheGalapagosIslands.ThereforeoneofthegoalsofthemodelistoidentifyalltheindividualbasedcharacteristicsoftheprocessthatarerelevantindeterminingtheoverallemergentdynamicsofatouristicdestinationliketheGalapagosIslands.Inthisperspective,thecomparisonbetweenthemodeloutputandtherealworldempiricaldatawouldpermitustoevaluateiftheindividualbasedelementsusedtobuildthemodelaresignificantornot.AnotherobjectiveofatouristdestinationABMliketheonepresentedinthispaperistoprovidetopublicpolicymakersatooltotesttheconsequencesoftheirmanagementdecisions.

Entitiesstatevariablesandscales

3.6 Themodeliscomposedoffivemaintypesofentities:touristagents,accommodationofferagents,themarketoperatoragent,thetouristagentgenerator,andthegeographicalenvironmentcircumstancesthatrepresenttheGalapagosIslands.

http://jasss.soc.surrey.ac.uk/17/1/14.html 3 15/10/2015

Figure3.Themixed,spatialexplicitandgraph-likerepresentationofthegeographicalenvironmentoftheGalapagosarchipelago.EveryIslandisthevertexofatransportationgraph.Onlytheareainsideeveryislandistreatedexplicitly

3.7 Figure3showsthegeographicalenvironmentrepresentation,characterizedbymixinganexplicitspatialrepresentationwithatopological,graph-basedrepresentation.ThefourinhabitedislandsoftheGalapagosArchipelago,i.e.,SanCristobal,SantaCruz,Floreana,andIsabela,arerepresentedasverticesonagraph.Theedgesareusedtorepresenttransportationconnectionsbetweenislands.Twoislandsareconnectedbyanedgeifanavailabletransportationoperationexistsbetweenthem.Weightsaregiventoedgestospecifythecostandtheamountoftimeoftransportation.Someoftheislandsaredefinedasentrancehubs,becausetheyhostanairportfromwheretouristsenterthearchipelagofromtheEcuadorianmainland(i.e.,SanCristobalandSantaCruzthatareaccessedthroughthenearbyBaltraIslandairport).Notethataninter-islandairlineserviceconnectsSanCristobal,SantaCruz,andIsabelaislandsusinglowcapacity,smallaircraftbutlocalcommercialboats(i.e.,"fibras")arethemostcommonwayofmovingbetweenislands.Thereforeinthemodelonlytransportationsbyboatwillbeconsidered.Thespatiallyexplicitrepresentationoftheinnerterritoryofeveryislandisdenoted,includingthenetworkofroadsandthetouristicoffers,representedaspointslocatedalongtheroadnetwork.Moreover,weassociateacertainnumberoftouristicattractionstoeachoneofthepopulatedislands.

3.8 Thetouristagentsaredescribedbythefollowingstatevariables:age,budget,stay,reservationflexibility,reservationanticipation,group,andcharacter.Thevariable"budget"istheamountofmoneythatthetouristagentspendsduringhistouristicexperience.Thevariable"stay"isthelengthofthetouristicexperience,whereas"reservationanticipation"isthetimeintervalbetweenthedateofbookingandthedatethetouristagentbeginsthetrip.The"reservationflexibility"representstheextenttowhichthetouristagentcanchangetheanticipation,andthevariable"character"isaderivedvariablethatreferstothetouristagentpreferencefordifferentaspectsofatouristicexperienceintheGalapagosIslands.Thevariable"group"indicateshowmanypeopletraveltogetherwiththetouristagent–whenthevariablevalueisgreaterthan1thetouristisconsideredtobeagroupofagentmakingthesamedecisions.The"character"variablehasfivedimensions:worldheritage,activities–sports,sun–beach,all-inclusive,andexclusivity.Eachdimensionhasvaluesbetween[0,2]–0forlowinterest,2forhighinterest.The"worldheritage"dimensionindicateshowmuchthetouristagentisinterestedinseeingGalapagoswildlife."Activities–sport"isthetouristwillingnesstoaccesslandandwatersports(e.g.,horsebackridingandkayaking)andothertouristicattractionswiththeexclusionofwatchingwildlife,while"sun–beach"isthewillingnesstoexperiencebeachlife(e.g.,swimmingandsunbathing)."All-inclusive"indicateswhetheratouristagentisinterestedinbuyinganall-inclusivetouristicexperience(i.e.,generallyatourledexperiencethatincludesalllandandwateractivities,arrangedmealsandlodging,andtransit),andlastly"exclusivity"indicatestheextenttowhichthetouristagentisinterestedinstayinginanexclusivetouristicfacility(i.e.,afullservice,resort-typeaccommodation).

3.9 Theaccommodationoffersarecharacterizedby:type,time,capacity,category,price,location,andfeatures."Type"couldtake"hotel"or"cruise"values."Time"istheminimumamountoftimeduringwhichtheofferappliesforatouristagent.The"Capacity"isdefinedashowmanypersonscanbeaccommodatedinanofferatthesametime,whilethe"Category"istherankassociatedtotheoffersaccordingtotheiroverallquality."Price"isthecostofahotelnightoraboatcruisethroughtheislands(refertotheTouristreservationsubmodeltoseehowcruisesandhotelspricesarecompared)."Location"isspecifiedonlyforland-basedaccommodationtypesandindicatesthegeographicpositionofhotelsonthecorrespondingisland."Feature"isanofferstatevariablethatcorrespondstothe"character"touristagentstatevariable,owningthesamefivedimensionsandvalueranges.Theoffer"features"indicatestheextenttowhichtheoffersatisfiestheexpectationofatouristagentinthefivedifferentdimensionsofthevariable.Theactualnumberoftheaccommodationoffersinthesimulationandthevaluesoftheirstatevariablesareassignedtothetouristicoffers,inthemodelinitialization,toreproducetherealworldstateintheGalapagosArchipelagoofEcuador.

3.10 Themarketoperatoragentisdefinedbythefollowingstatevariables:periodicity,priceincreasethreshold,priceincreaserate,pricedecreasethreshold,pricedecreaserate,numberofrandomoffercreations,operatingexpensesparameters,offercostparameters,offerdepreciationrate,numberofyearsofthenetpresentvalue,yearlydiscountrate,reinvestmentrate,andbankruptcythreshold.ThemarketoperatorstatevariablesaredescribedinTables6and7inAppendixA.

3.11 Thetouristagentgeneratorisnotstrictlyanagent,asitcouldbeconsideredamoduleinthemodelwherealltheparametersneededtogeneratetouristagentsarestored.Itisdefinedbythefollowingstatevariables:periodicity,numberoftouristagentsperyear,numberofageclasses,andseasonaltuning.ThetouristagentgeneratorstatevariablesaredescribedinTable12inAppendixA.

Processoverviewandscheduling

3.12 Thetimestepofthemodelisoneday.Monthsaredefinedascomposedby30days,andyearsaredefinedascomposedby12months.Hotelsandcruisesoperatewithadailytimestep,registeringthenumberoftouristagentstheyhost.Themarketoperatoragentfollowsatimestepdefinedbyitsperiodvariablethat,inthisstudy,isalwayssetatamonth.

3.13 Whentouristagentsaregeneratedbythetouristagentgenerator,theyimmediatelyattempttoreserveanaccommodationoffer.Iftheydonotsucceedinfindinganaccommodation,theyexitfromthesimulation.Ifthetouristagentsucceeds,theagentwaitsuntilthedatescheduledbythereservation,thenswitchestothe"trip"stateandtheagentisthenregisteredintheofferthatwasbooked.Inthecasewherethetouristagentbookedahotel,eachsimulationdaytheagentsearchesforanewaccommodationforthenextday.Wenotethat,inthisway,thetouristagentscannotreserveahotelformorethanoneday.Ofcourse,thisisnotwhatactuallyhappensintherealworldasincertaincasesatouristwantstobookinthesameplaceformorethanoneday.However,thereservationprocesswasdesignedinthiswaybecausewehavenoinformationaboutthepercentageoftouristsbookinghotelsinadvanceinGalapagosformorethanoneday.Alsoallowingtouristagentstobookformorethanonedayinadvancewouldimplythatthetouristagentcouldcancelthereservationincasehewantstochangeplacebeforeofthereservationends.Inthiscircumstancethetouristagentisforcedtopayafinebutthenagainwehavenodataaboutcancellationpoliciesappliedinthehotels.

3.14 Everysimulationday,theland-basedtouristagentssubtract3touristicattractionsfromthelistoftheunvisitedtouristicattractionoftheislandwheretheagentsareactuallylocated.Thissimulatethefactthattheland-basedagentgothrough,asdailyaverage,3activities,forexamplevisitinganaturalenvironmentsite,takeawalkalongahighlandtrack,andtakeasunbathonalocalbeach.Inthisway,whilethetourist

http://jasss.soc.surrey.ac.uk/17/1/14.html 4 15/10/2015

agentremainsinthesameislandIA,thenumberofunvisitedtouristicattractionassociatedtoIAwilldecreaseeverydaybythreeunits.Afteracertainnumberofdays,forthetouristagent,inanotherislandIBofthearchipelago,thenumberofunvisitedtouristicattractionswillbehigherthanintheislandIA.Aswewillseeinthe"Touristreservationsubmodel"section,thetouristagentstendtoreserveaccommodationofferslocatedintheislandwiththehighernumberofunvisitedtouristicattractions.ThereforewhenthenumberofunvisitedtouristicattractionsintheislandIAwillbelessthanthenumberofunvisitedtouristicattractionintheislandIB,theagentwillbepushedtobearthecosts–intimeandmoney–ofmovingfromanislandtoanotherisland.

3.15 Ifthetouristagentbooksacruise,theagentfollowsthecruisejourneythatincludesimplicitly3dailyactivities.Attheendofthecruisejourney,andifthelengthofhis/herscheduledstayisgreaterthanthelengthofthecruisejourney,theagentattemptstobookahotel.Notethatthestopoverdestinations,thenumberofstops,andthenumberofdaysofeverycruisejourneyarestrictlyregulatedbytheGalapagosNationalParkandcannotbechangedbytheboats'owners.Moreover,thecruisesstopoversneverincludenightsoffboardsotheboat-basedtouristagents,whiletheyareincruiseneveruselandaccommodationoffers.

3.16 Themarketoperatorcalculatestheprofitorlossandtheaveragenumberofhostedtouristagentsforeveryaccommodationofferinthemodel,anddecideswhethertocreatenewoffers,removeoldoffers,orincrease/decreaseprices.

http://jasss.soc.surrey.ac.uk/17/1/14.html 5 15/10/2015

Figure4.Flowdiagramoftheprocessessequenceofagentsinthemodelintheirlifecycle.

3.17 AflowdiagramofthelifeprocessofeveryagentinthemodelisshowninFigure4.NotethatthemaximumnumberofcruiseboatswithregularoperatingpermissionisstrictlyregulatedbytheGalapagosNationalPark.Forthisreason,weimposedthatthetotalnumberofcruisesduringthesimulationisnotgreaterthantheinitialnumberofcruisesintheinputdata.ThetotalnumberofhotelsisnotsostrictlyregulatedbytheGalapagosNationalParksothenumberofhotelsinthesimulationcanchange.

Softwareandhardwareenvironment

ThemodelhavebeenimplementedintheMASON(Lukeetal.2005)environment.MASONisafree,Java-based,discrete-event,multi-agentsimulationlibrarycoreusedtoreducetherepetitivecodewritingeffortnecessarytodevelopanABM.Everyrunof15yearswith200,000generatedtouristsperyearrequiresapproximately4CPUhoursonanIntelPentiumDual2.40GHz.

DesignConcepts

Emergence

3.18 Manymacroscopicpatternsemergefromthetourist,offer,andmarketoperatoragents'individualbehaviors–themodelreproducetherelativeproportionofland-andboat-basedtouristsandthespatialdistributionofaccommodationoffersandtouristagentsacrosstheGalapagosArchipelago.

Adaptation

3.19 Themarketoperatoradaptstheaccommodationofferstotheavailableenvironmentconstitutedbytouristagents.Theprocessispermittedbythevariationofoffersprices,replicationofmostbookedoffers,andtheeliminationofun-bookedoffers.Onlytheoffersthatsatisfymostthetouristagentpreferenceswillsurviveandreplicate.

Objectives

3.20 Thetouristagents'aimistofindthemostsatisfyingaccommodationofferandmaximizethenumberofpossibletouristicattractionsenjoyedduringthetrip.Thepurposeofthemarketoperatoristoproduceanoffers'populationthatsatisfytouristagentsmost.

Knowledge

3.21 Touristagentsandmarketoperatorhaveanunrestrictedaccesstoinformation.Thismeansthatineverymomenttheyknownexactlythecharacteristicsofeveryaccommodationoffer.Evenifitisknownthattheaccesstoinformationintherealworldtourismmarketcouldbeasymmetricandnotcompletewemakethisassumptionforthesakeofmodel'ssimplicity.

Interaction

3.22 Touristagentsinteractwithofferstolearnaboutthehotel'sbedsavailabilityaswellasboatberths,andtogetinformationabouttheoffers'features.Marketoperatorsinteractwithofferstodeterminewhetheritisnecessarytointroducechangesintheoffers'environment.

Stochasticity

3.23 Alltheparametersdefiningthetouristagentcharacteristicareconstructedasstochasticvariables,astheyareextractedrandomlyfromempiricalprobabilitydistributions.TheseempiricaldistributionsaretheresultoffieldsurveysinwhichasampleoftouristsvisitingGalapagosIslandswasinterviewedthroughapre-testedsurveyinstrument.Moreover,astochasticfactorisextractedtogettheextenttowhichtouristicoffersaredifferentinrespecttotheirduplicates.

Observation

3.24 Duringsimulation,wemonitorthenumberofland-andboat-basedtouristagentsvisitingtheGalapagosIslandsandthenumberoftouristagentsineachofthepopulatedislands.

Details

3.25 Inthissection,wedescribetheinitializationprocessandtheinputdatausedtoinitializethestatevariables.Furthermore,thesubmodelsthatcontaintheequationsandrulesofthemodelarepresented.

Initialization

3.26 Atthebeginningofeachsimulationruntheislandparametersarereadfromtheconfigurationfiles.First,thearchipelagographischarged.InTable2inAppendixA,theparametersdefiningthearchipelagotransportationgrapharereported.Next,theshapefilecontainingthecoastlineofeveryislandisread.ThecoastlinesdatawereobtainedfromtheINGALA,NationalInstituteofGalapagos,nowrenamedtheGovernmentCouncilofGalapagos.Then,thegeographicalcoverageoftheroadsnetworkisread(dataobtainedfromtheEcuadorianInstituteofStatisticsandCensus,INEC),followedbytheshapefilecontainingthehoteldata.TheinformationabouthotelsinGalapagosisobtainedfromtheGalapagosTourismMonitoringCenter.Cruisesarealsoinitializedinthemodel,informationobtainedfromtheGalapagosNationalParkandtheGalapagoscruisespromotionorganization(www.crucerogalapagos.com).Pricesofhotelswereobtainedthroughatelephonesurvey.Afterthegeoreferencedinformationisread,thesimulationbegins.ThenumberoftouristicattractionsofeveryislandinthearchipelagoisreportedinTable3inAppendixA.NotethattouristicactivitiesarestrictlydelimitedbytheGalapagosNationalParksoweknowexactlyhowmanyactivitiesareofferedtotouristsineveryisland.Theactualvalueofeverystatevariableofeveryindividualtouristagentisextractedfromempiricaldistributionsfromthe2011fieldsurveyoftheGalapagosTourismMonitoringCenter(ObservatoriodeTurismoGalapagos2011).Notethattheempiricaldatawehaveusedindicateonlythetotaltouristagent'sexpenditurefortheGalapagostrip,includingtheairticketfromtheEcuadorianmainlandandtheparkentrancefee.BecausetheairticketpricesandtheGalapagosNationalParkentrancefeesaredifferentfornationalandforeigntourists,wecalculatedtheactualbudgetavailablefortourismintheGalapagostoeverytouristagentbysubtracting$450.00(USD)fortheairticketand$100.00(USD)fortheparkentrancefeeappliedtothe78.16%ofthegeneratedtouristagentthatareconsideredasforeigntouristagents,and$350.00(USD)fortheairticketand$16.00(USD)fortheparkentrancefeeappliedtothe21.84%ofthegeneratedtouristagentsconsideredasnationaltouristagents.Thevaluesofthetouristagent'sstatevariablearereportedinTables3and4inAppendixA.Theoffers'variablefeatureisdeterminedbythecharacteristicsoftheoffer.Forhotels,WorldHeritagevaluesaresetto0,1or2dependingonthedistancefromthecentroidoftheislandroadsnetwork–2fordistanceslargerthan10,000m,1fordistancesbetween10,000mand8,000m,and0forhotelswithadistancebelow8,000m.ThesameWorldHeritagevalueissetto2forcruises.Theactivities-sportvalueisassignedtohotelsandcruisestobeproportionaltotheCategory.Sun-beach,forhotels,aresetto1or2dependingonthedistancefromtheislandcoastline–2fordistancessmallerthan100m,and1fordistancesgreaterthan100m.Sunandbeachissetto0forcruise.Wenotethat,inthisway,theislandsthatshowroadswithmoreextensionalongtheseafronttendtobemoreattractiveforsunandbeachtouristagents,whileislandsthatshowroadsthatbringtouristagentsfarfromtheurbancenterstendtobemoreattractiveforworldheritagetypetouristagents.AlltheoffersfeaturevariableassignmentsarereportedinTable6inAppendixA.

3.27 Thetime-seriesofthetouristagentsgeneratedforonesimulationyearisproportionaltothehistoricalseriesofvisitingtouristsinGalapagos,extractedfromtheGalapagosNationalParkstatistics(ParqueNacionalGalápagos2012).

Submodels

Touristreservationsubmodel

3.28 Thissubmodeldefinesthewaytouristagentschoosetheaccommodationthattheybook.Whenatouristagentiscreatedinthesimulation,thefirstactiontheagentperformsistotrytobookanaccommodationoffer.Iftheagentbooksahotel,thetouristagentisdefinedasaland-basedtouristagent.Thissubmodelisdescribedasfollows:

1. Thetouristagentusestheoffercomparatormoduletobuildasortedlistofalltheavailableoffers.Ifthisistheinitialapplicationofthecomparatormodule,allpossibleland-andboat-basedoffersareincluded.Iftheagentwishestorenewaland-basedreservation,theagentincludesonlyhoteltypeoffers.

2. Startingfromthetopofthesortedlist,thetouristagentexaminestheaccommodationoffersandbooksthefirstofferwithapricewithintheagent'sbudgetandwithavailableroomsduringthedatesofthedesiredtrip.Iftheendofthelistisreached,theagentexitsfromthesimulation.

ThetwostepsprocesscorrespondstothediagrampresentedinFigure5.

http://jasss.soc.surrey.ac.uk/17/1/14.html 6 15/10/2015

Figure5.Flowdiagramofthereservationsubmodel

3.29 TheOfferComparatormoduleworksinthefollowingway:thetouristagentgeneratordividestheintervalfromtheminimumtothemaximumtouristagents'budgetintonsubintervals.Wedefineas"lowbudget"and"highbudget"thegeneratedtouristagentswithabudgetbelongingtothelowerandhigherlevelsoftheconsideredbudgetsubintervals,respectively.Theremainingtouristagentswillbedefinedas"mediumbudget"touristagents.Dependingonthebudgetsegmentthetouristagentbelongs,theagentwillapplyadifferentstrategytosorttheaccommodationoffers:lowbudgettouristagentswillpreferlowestpriceoffers,thehighbudgettouristagentwillpreferthehighestqualityoffersandthemediumbudgettouristagentswillfollowabestqualityforminimumpricestrategy(Piana2004).Indetail,thelowbudgettouristagentswillsortoffersaccordingtothefollowingcondition:theofferO1precedestheofferO2ifP1<P2wherePiisgivenby:

Pi=pbi+Tci

HerepbiisthepriceforaroompernightfortheofferOiandTciisthetransportationcosttoreachtheislandwheretheofferOiislocatedfromtheclosestentranceisland(iftheofferOiislocatedinanentrancehubthenTci=0).CruisesalwaysembarktouristagentfromSantaCruzorSanCristobalsoTci=0forcruises.InthecasewheretwoormoreofferspresentthesameP,theOfferComparatorModulewillorderthematrandom.Toallowcomparisonsbetweentheaccommodationpriceofanall-inclusivetouristicoffer,likeacruiseandanoffersuchasahotelforwhichtheaccommodationpriceonlyincludestheexpensesforthenightstay,itisnecessarytoconsiderthepriceofthehotelasifthehotelwhereanall-inclusivetouristicoffer.Toaccommodatethatinthemodel,aspecificparameterisdefined–thedailyexpenserate,aratiobetweenthetotalaveragedailyexpensesofaland-basedtouristagentandtheaveragepriceforonenightinahotel.Bymultiplyingthepriceofahotelbythedailyexpenserate,itispossibletoobtainacorrectedhotelpricethatiscomparabletocruiseprices.Below,allthehotelspricesareintendedascorrectedpricesandthedailyexpensesrateissetto3(Epler2007).

3.30 Thehighbudgettouristagentwillconsideroffersthroughthefollowingcondition:theofferO1precedestheofferO2iftheoverallqualityQ1isgreaterthanQ2.Theoverallqualityisdefinedas:

Herefijisthej-thelementofthefeaturevariableoftheofferOi,whilecjisthej-thelementofthetouristagent'scharactervariable.Moreover,NiisthenumberoftouristicattractionsassociatedtotheislandwheretheofferOiislocated.TtiisthetransportationtimetotraveltotheislandwheretheofferOiislocatedfromanentranceisland.Lastly,Aistheagefactorassociatedtothetouristagent–asinthecaseoftouristagents'budget,thetouristagentgeneratorseparatesthegeneratedtouristagentsbyageintoacertainnumberofageintervals,definingas"youngaged"and"oldaged"theagentsthatcorrespondtothelowestageandhigherageintervals,respectively.Theremainingtouristagentswillbedefinedas"middleaged"touristagents.TheagefactorAisdefinedtobeequalto1,2or3fortouristagentsbelongingtotheyoung,middleandoldagedclasses,respectively.ThethreefactorsCf,CN,andCAareparametersthatwillusedtocalibratethemodel.

3.31 Forthemediumbudgettouristagent,theofferO1precedestheofferO2ifR1>R2.Riisthequalitypriceratioanditisdefinedas:

Ri=Qi/Pi.

Whenthetouristagentisalreadyaccommodatedinahotelandtheagentislookingforanewaccommodationforthefollowingday,theexpressionusedtoindicatetheoverallqualityofthetravelexperienceisslightlydifferent:

HereNεiisequaltothenumberofthetouristicattractionsnotvisitedbythetouristagentontheislandwheretheofferOiislocated.Theislandswithmorenotvisitedtouristicattractionwillbemoreattractiveforthetouristagent.Theparameterεitisalwaysequalto0andisequalto1onlyiftheofferOiisnottheofferwherethetouristagentisactuallyaccommodated.

Marketoperatorsubmodel

3.32 Thissubmodeldefinesthemarketoperatordecision-makingrules.Themarketoperator(MO)usestheprofitgeneratedbyanoffertocreatenewofferssimilartoasuccessfuloffer.ThestepsfollowedbytheMOtodecideifanoffershouldbe"replicated"areasfollows:

1. Calculatethetotalprofitaccumulatedbytheofferanddetermineifitishighenoughtocovertheinvestmentneededtobuildacopyofthestartingoffer.2. CalculatetheNetPresentValue(NPV)ofthenewoffer.AnewofferwillbecreatedonlywhenNPVispositive.

3.33 ThetotalprofitPoftheoffersisdefinedasthesumofallthedailyprofitspiovertheperiodfromthelastreplicationorfromthecreationoftheoffertothepresenttimeminustheaccumulatedrenovationcosts:

HereNdaysisthenumberofdaysbetweenthecreationorthelastreplicationoftheofferandthepresenttime,whileDcisthecostduetotherenovationaccumulatedbytheofferinthesameperiod.Inaddition,oiandpbiaretheoccupancyandpriceperbedorberthoftheoffercorrespondingtothedayi.ThevariablesCcapandboerepresentthecapacityandtheoperatingexpensesper"bed"respectively.Indetail,theoccupancyisthenumberofoccupiedbedsandtheoperatingexpensesarethecostperday,perbedtomaintaintheoffer.boe,isafunctionofthecharacteristicsoftheofferasfollows:

whereCatcouldtakethevalues0,1,2and3,fiisthei-thelementoftheofferfeaturestatevariableandαe,βeandγearetheparameterspresentedinTable10forHotelsandTable11forCruises.

3.34 Notethatboeautomaticallydefinesminimumrentablepricefortheoffer:

prent=boeprentinturndefinestheminimumacceptablepricepmin:pmin=prent·fmp

http://jasss.soc.surrey.ac.uk/17/1/14.html 7 15/10/2015

Wherefmpisafactorthatissettobe1.2.

3.35 Theinvestmentneededtoduplicatetheoffer,inthecaseofhotels,isproportionaltothefeaturesandcharacteristicsoftheoffer:

whereABistheaverageareaperbedasfunctionofthecategoryCat,Pm2isthebuildingpricepersquaremeterasfunctionofthecategory.ThevaluesoftheparameterspresentedinthislastequationhavebeendeterminedthroughafieldsurveyofdepartingtouristsonSanCristobalandSantaCruzIslandsandtheresultingvaluesarepresentedinTable8inAppendixA.ForCruisestheinvestmentexpressionisasfollows:

Ic=Cap·αi(Cat)

whereαi(Cat)isaparameterdependentontheCruisecategory.ThevaluesforαIarepresentedinTable9inAppendixA.

3.36 WenotethattherenovationcostDcintheaboveexpressionoftheprofit,isequalsto:

Dc=a·dr·IH.C

Herea,istheageoftheofferinyearsanddristhedepreciationannualrate.Asresultofourfieldsurvey,wesetdr2.5%forhotelsand3.5%forcruises.

3.37 Oncetheconditionatpoint1issatisfied,theMOevaluatesconditionnumber2,calculatingtheNetPresentValue(NPV)ofthenewofferthatrepresentsthecost-effectivenessoftheinvestmentforanewoffer.TheNPVisexpressedas:

whereNisthenumberofyearsinwhichtheinvestmentmustberecovered,<O>isthedailyaverageoccupancyoftheofferthatisduplicated,calculatedinthelastyearofactivity,pbisthepriceperbedpernightoftheduplicatedofferatthetimeofduplication.FurthermoreDRTisthediscountratefortheyeartandIistheinvestmenttocreatethenewofferpresentedabove.Thediscountrateistherateofreturnthatcouldbeearnedonaninvestmentinthefinancialmarketswithsimilarrisk.AlltheoffersthatfulfilltheconditionsP·Rr>IandNPV>0arereplicated.Whenthereplicationisdone,thecumulatedprofitofthereplicatedofferissettozeroandthesameofferwillnotbereplicateduntiltheconditionsatpoints1and2aresatisfiedagain.Thenewofferwillbenotanexactcopyofthereplicatedone–allthefeaturesandcharacteristicsofthereplicatedofferwillbechangedbyasmallstochasticfactorSc=10%togiverisetoaslightlydifferentnewoffer.Inthatway,wecreateanofferecosystemwherenotonlythefittestoffersarereplicatedi.e.,theoffersthatcanaccumulateprofitfastest,butwherewealsointroduceerrorsintheprocessofreplicationtopermittotheoffers'ecosystemtoadapttothetouristagentfeaturesenvironmentfasterandmoreefficiently.Whenahotelisduplicated,anewhoteliscreated.Thisnewhotelisplacedinarandompositioninsidetheroadsnetworkofthesameislandoftheparenthotel,withadistancefromtheparenthotelbetween100and1600m.Alsonewhotelshavenottobecloserthan20mtootherestablishedhotels.Ifanaccommodationoffershowsapassiveprofit(P<0),andthepassiveabsoluteisequaltothebankruptcythresholdmultipliedforthecost(I)oftheoffer,themarketoperatorwilldestroytheoffer.

3.38 Theseconddecisionmakingprocessofthemarketoperatoristheofferpricevariation.Iftheoffer'saverageoccupationisabovethepriceincreasethresholdpresentedinTable7inAppendixA,theMOwillincreasethepriceoftheofferbyafactordefinedbythepriceincreaserate.Ontheotherhand,iftheaverageoccupationisbelowthepricedecreasethreshold,theMOwilldecreasethepriceoftheofferbyafactordefinedbythepricedecreaserate.Thepriceofanofferwillbeneversetbelowtheminimumacceptablepricepmindefinedabove.

Modelverification,CalibrationandValidation

Verification

4.1 Theverificationprocessconsistsofobtainingaconfirmationthattheimplementedprogramcodebehavesasplannedinthedesignphase.Toverifyourmodel,weappliedthefollowingstrategy:first,weexaminedeverycodelinetoconfirmitsfunctionandcorrectness;second,weperformedanextremevaluetestforeveryparameterinthemodel,includingempiricaldata,provingthatthesystemrespondsintheexpectedway,andthird,webuiltanoversimplifiedtestmodelwithonlyafewtouristsandaccommodationoffersagentsandwecloselyexaminetheresults,checkingthateveryagentbehavedintheappropriatemanner.

CalibrationandValidation

4.2 Thecalibrationistheprocessofadjustingthevalueofsomeoftheindependentparameterstochangetheresponseofamodelinsearchofanempiricaladequacy.Thevalidation(afterCrooksetal.2008;Ligtenbergetal.2010)consistsofcontrollingthattheoutputfromamodelproducesresultsthataresufficientlyclosetothedataofthecorrespondingrealworldsystem,withinthelimitsandtheobjectivesofthemodeling.Calibrationandvalidationarequiteinterconnectedprocesses,becauseduringthecalibrationprocess,theparameterspaceisrestrictedtoobtainamodelthatcanbeconsideredasvalidated.

4.3 OurmodelwasdesignedtoreproducemacroscopicfeaturesoftourismintheGalapagosIslands,suchastherelativeproportionbetweenland-andboat-basedtourismandthespatialdistributionoftouriststhroughoutthearchipelago.Therefore,thevalidationprocessconsistsinverifyingthattheland-andboat-baseddistributionsandthespatialdistributionoftouristagents,predictedbythemodel,isinagreementwithdatasetsfromtheGalapagosNationalParkandtheGalapagosTourismMonitoringCenter.

4.4 Weperformedthecalibrationprocessbyvaryingthevalueofthreeparameters:Cf,CN,andCA.Thesethreecalibrationparametersarepresentedinsection"Submodels"intheexpressionoftheaccommodationoffersqualityQandareusedtobalancethecontributiontotheofferquality,originatingfromtheofferfeaturesterm,theislandstouristicattractionsterm,andtheageterm.Beinginvolvedintherepresentationofthetourist'sdecision-makingprocessand,therefore,intherepresentationofmentalprocesses,thesethreefactorsareusedascalibrationparameters,becauseitwouldbeverydifficulttoobtainameasureofthem.Weperformedasystematicsearchinthisthree-dimensionalparameterspaceandweselectedthevectorvaluethatgivesusthebestapproximationoftheobservedproportionbetweenland-andboat-basedtouristandofthedistributionoftouristsinthefourinhabitedislandsoftheGalapagosArchipelago.Asthemodelincludesdifferentstochasticfactors,distinctrunsproducegenerallydistinctresultsintermsofthesimulatedsystemhistory.Forthisreason,weaveragedtheoutputsfrom10independentrunsof15year.Thenwecomparedtherealworlddatawiththeaveragevaluesoverthelast7simulationyearsoftheresultingaveragedsimulatedhistory.Inthisregard,weconsideredthefirst8simulationyearsasatimeintervalduringwhichthesystemcanreachalocalequilibrium,allowingtheaccommodationofferstoadjusttheirpricesandnumberstothecharacteristicsofthetouristagents.Thecalibrationisonlyaqualitativeprocessbecauseweknowempiricaldataonlyapproximatelyandwedonothaveaccesstoempiricaltime-seriesdata.

4.5 Fromthe2011GalapagosNationalParkstatistics,weknowthatapproximately43%oftouriststouredthearchipelagoaspartofacruiseandthat23%ofpeopleenteredthearchipelagothroughSanCristobalIsland.Moreover,fromtheGalapagosTourismMonitoringCenterreport,weknowthatapproximately20%oftouristsreservedacruiseandthenarrangedforahotelattheendofthecruise.AsurveyfromtheTourismAssociationofIsabela(ArucariaXXI2007)showsthatin2007nearly12,000touristsvisitedIsabelaIsland,whichaccountsfor8%ofthetotalnumberoftouristsvisitingGalapagosin2007.Usingtheseabovepercentagereportsofuseandgeneralaccess,wecalibratedthemodel.

Calibrationresults

4.6 InFigure6,weshowthefinalcalibrationoutputscorrespondingtothevalueofthecalibrationvector(Cf,CN,CA)=(1,2,0.2).Afteraninitialequilibrationperiod,thecurvesrepresentingthemonthlynumberoftouristagentsreservingcruisetripsorvisitingthefourinhabitedislandsreachaplateau.TheplotsinFigure6alsoshowatypicalseasonalbehaviorbetweenthemonthsofSeptemberandOctober,theperiodwithlowesttouristicpresence.InFigure7weshowsomesnapshotsfromthecalibrationsrun.InthisFigureisrepresentedasmallportionofthetotalsimulationspace:theareaofPuertoAyorathat,asshowedinFigure1,isthemaininhabitedcenteroftheSantaCruzIsland.Aswecanseeinthetimeseriesofthethreereportedsnapshot,duringthesimulationtime,somehotelsareremovedfromthesimulation,whileotheracreated.

http://jasss.soc.surrey.ac.uk/17/1/14.html 8 15/10/2015

Figure6.Calibrationmodeloutput.Intheuppergraphareshowedthemonthlytotalnumberoftouristagentreservingacruise(blueline)orahotel(redline)asfirstoption.Thegreenlineinthesamegraphisthemonthlynumberoftouristagentreservingahotelafterreservingacruiseasfirstoption.ThebottomgraphshowsthemonthlytotaltouristicpresenceinthefourinhabitedislandsoftheGalapagosarchipelago.

http://jasss.soc.surrey.ac.uk/17/1/14.html 9 15/10/2015

Figure7.Snapshotpicturestakenfromthecalibrationrun.InthethreesnapshotsisrepresentedthecentralpartofPuertoAyorathatisthemainurbanareaoftheSantaCruzIslandwherethemajorityoftheisland'shotelsarelocated.Roadsarerepresentedtroughblacklines.Greensquaresarehotel.Bluesquaresarenewhotelcreatedduringthesimulationtimebetweenthetimeofthecurrentsnapshotandthetimeoftheprecedingsnapshot.

Table1:OutputsfromtheABMsimulations–fractionsofthetotalnumberoftouristagentgeneratedinthelast10-yearofthesimulationruns.

Boat-based Land-based Landafterboat SanCristobal IsabelaEmpiricaldata 0.42 0.58 0.20 0.23< 0.08

ReferenceRun 0.44 0.56 0.26 0.16 0.08Whatifscenarios

AirportinIsabela 0.43 0.57 0.25 0.17 0.08Tourismcollapse 0.44 0.58 0.26 0.16 0.06Parkticketincrease 0.76 0.24 0.59 0.08 0.07

4.7 InTable1,weshowtheresultsofthelast7-yearrunaverages.Inthistable,wereportthefractionofthetotalnumberoftouristagentsenteringthesimulationandreservingacruiseastheirfirstchoice(i.e.,boat-basedtouristagent),thefractionoftouristagentsreservingahotelastheirfirstchoice(land-basedtouristagent),thefractionoftouristagentsthatreservedacruiseandthenreservedahotelroomimmediatelyafterthecruise(land-andboat-based),thefractionoftouristagentsvisitingSanCristobalIsland,andthefractionoftouristagentsvisitingtheIslandofIsabela.Wenotethatafterthefirstequilibrationperiod,thenumberandthespatialdistributionoftheaccommodationoffersisdifferentwithregardstotheinitialconfiguration.Indetail,thenumberofcruiseboatschangedfromaninitialvalueof66vesselstoanaveragevalueof47.2inthelast7-yearsofthesimulationruns.Furthermore,thenumberofhotelsinSantaCruz,SanCristobal,Isabela,andFloreanachangedfrom43,24,35and2to34.5,7.3,4.3and0respectivelyforthelast7-yearsofthesimulation.Inthecontextofourcalibrationprocess,thesechangesarenotsignificantbecauseweareinterestedinfindingastateofourmodelthatcanreproducethedistributionoftouristsamongland-andboat-basedoffersandamongtheislandsofthearchipelago,andnotthenumberanddistributionoftouristicoffers.

ABMexperiments

5.1 Themodelresultingfromthecalibrationprocesswasusedtobuildthree"whatif"scenariostostudytheresponseofthemodeltostatevariablechanges.Thethreescenarioswetestedwereasfollows:

a. OpeningofanewairportonIsabelaIslandwithdirectflightsto/fromtheEcuadorianmainlandb. Tourismcollapse–areductionofvisitingtouristsfrom180,000peryear(asrecordedin2011)to100,000peryearc. Increaseintheparkfeesfrom$6.00(USD)and$100.00(USD)fornationalandforeigntourists,respectively,to$400.00(USD)forallthevisitingtourists

Forallthethreetestedscenarios,weperformed1015-yearruns,permittingthesystemtoequilibrateforthefirst7-years,afterwhichwechangedthestatevariablesaccordinglytothe"whatif"experiment.

5.2 Indetail,theset-upofthe3"whatif"scenarioswere–forscenario(a)attheendofthe7thsimulationyear,wepermittedtouristagentstoenterthesimulationdirectlyalsofromIsabela.Togeneratescenario(b)attheendofthe6-hsimulationyear,wedecreasedthenumberofgeneratedtouristagentsby0.75peryeartogetthetotalnumberofgeneratedtouristagentsto112,500after2-yearsandthenwemaintainedas

stablethenumberofgeneratedtouristagents.Tocreatethescenario(c)attheendofthe7thsimulationyear,wesharplyreducedthebudgetavailabletoeverytouristagentby$400.00(USD).

ABMExperimentsResults

5.3 Theresultsofthe"whatif"scenariosshouldbeinterpretedasaninformationabouthowourmodelreactstocertainchangesinthestatevariables.Newempiricaldataareneededandadditionalvalidationdataarerequiredtodeterminewhetherthemodelissufficientlyrobusttosuitablyrepresentthedecision-makingofagentandsomeofthestochasticprocessesassociatedwithexogenousforcesandendogenousfactorsthatcombineincomplexwaystoaffecttouristicbehaviorsinresponsetomarketconditionsandadynamicenvironment.

5.4 InTable1,theaveragefractionsoftouristagentsobtainedinthecalibrationprocessarereported.Wenotethatforscenarios(a)and(b),themodeldoesnotshowanysignificantchangeregardingthereferencecalibrationrun.Scenario(c)showsthatchangesinthemodelstatevariablesgenerateastrongerinfluenceonthesimulationoutputs.

5.5 Wecanassumefromtheseresultsthatifwedonotchangetheindividualbasedcharacteristicsofthevisitingtouristagents(suchasthetouristagents'budget),onlychangesomeaspectsofthetouristicinfrastructure(e.g.,anewairport),andchangethetotalnumberofarrivingtouristagents,thiswillnotaffecttheobservedemergentpatterns.WithanewairportinIsabelaandwithoutanupgradedtouristicinfrastructureonthesameislandthatisabletoattractandhostanincreasednumberoftouristagents,intheshortterm,nochangeinthetouristagentdistributionwillresultamongtheislandsofthearchipelago.ThismayoccurbecauseSantaCruzIsland,duetohisstrategicandcentralgeographicalpositioninthearchipelagoandasthehubofthetourismindustry,willremainthefocalpointoftourismintheGalapagosIslands.Assuch,SantaCruzIslandsubstantiallyinfluencestourismmobilityaroundthearchipelagoand,therefore,willstillattractthelargestportionofthevisitingtourists.Wecanexpectasimilarpatternforasuddendecreaseintourists'arrivals–withoutanyotherchange,thevisitingtouristswillbedistributebetweenland-andboat-basedtoursandamongthearchipelagoislandsinanunalteredmanner.

5.6 Thecircumstanceschangecompletelywhenwealtersomeofthecharacteristicsofindividualtouristagents.Inscenario(c),theincreaseintheentrancefeestotheGalapagosNationalParkcompletelyaltersthetouristagent'sabilitytogainaccesstothedifferentsegmentsoftheGalapagostouristicmarket.Inthislastcase,theproportionofland-basedtouristagentscollapsesto24%ofthearrivingtouristagents,whiletheboat-basedtouristagentsassume76%ofthevisitingtouristagents.Wenotethatinthisscenario,theaveragenumberoftouristagentssucceedinginreservinganaccommodationofferoneverysimulationmonthfallsfrom14,880ofthecalibrationreferencemodel,to8,322registeringadecreaseofabout56%.Clearly,thetouristagentsthatareremovedbythereservationprocessarethelowbudgettouristagents.

Conclusion

6.1 ThedynamicsandchangesofatouristicdestinationlikeGalapagosIslandsdependonahighnumberofcombinedfactorsthat,inmostcases,actalsoattheindividualscaleoftouristsandtouristicoffers.Inthispaper,wehaveshownanapproachtodevelopanAgentBasedModeloftouristicoffersandreservationintheGalapagosIslands.Theresultingmodelis,asusualinanABM,amultidisciplinaryassembly,whereelementsfromtourismmarket,economy,psychology,andgeographyarecombinedtocreateasystemthatrepresentssomeofthecharacteristicsofthetourismmarketoftheGalapagosIslands.ThemodelincludesapsychometricrepresentationoftouristsvisitingtheGalapagos,togetherwithadetailedrepresentationoftouristicaccommodationoffersandtouristicattractionsintheGalapagos.Weparameterizedthemodel,exploitingtothemaximumextent,theavailableempiricaldatasets.Someofthemodel'sparameterswhereusedtocalibrateitandtoreproducecloselyemergentpatternsoftourisminGalapagos.Themodeloutputsarequiteconsistentwiththeavailableempiricaldatasetsshowingthattheindividual-basedmechanismandprocessesdefinedtobuildthemodelcancloselyreproducesomeofthekeyaspectsoftheGalapagostourismmarket.Asindicatedabove,thismodelrepresentsafirststepinbuildinganABMthatwillincludeothersocialandenvironmentalaspectsofGalapagosIslandssuchasfisheries,agriculture,landcoverchange,andmore.Moreover,additionalcollectionandderivationofempiricaldataarenecessarytostrengthenthevalidationofthemodelandtoreproducemoreaspectsofthetouristicmarketintheGalapagosIslands.

Acknowledgements

TheresearchconductedinthegenerationofthismodelwasmadepossiblethroughagrantfromtheMcDonnellFoundationtotheUniversityofNorthCarolinaatChapelHill,USAandasub-contracttotheUniversidadSanFranciscodeQuito,EC.Inaddition,theauthorswishtothanktheGalapagosScienceCenter,apartnershipbetweentheUniversidadSanFranciscodeQuito,ECandtheUniversityofNorthCarolinaatChapelHill,USAforuseoffacilitiesandassociateddatasets.WeparticularlywishtothanktheGalapagosNationalParkfortheirassistanceandcooperation.

References

ARUCARIAXXI.(2007).SATISFACCIÓNDETURISTASQUEVISITANPUERTOVILLAMIL,ISABELA.ISLAISABELA–GALÁPAGOSJULIO2007(pp.1–25).

BAGGIO,R.(2008).SymptomsofComplexityinaTourismSystem.TourismAmalisys,13(1),1–20.[doi:10.3727/108354208784548797]

BALBI,S.,&Giupponi,C.(2010).Ca'FoscariUniversityof,(05).

BENSTED-SMITH,R.(Ed.).(1999).ABIODIVERSITYVISIONFORTHEGALAPAGOSISLANDS.CharlesDarwinFoundationandWorldWildlifeFund,PuertoAyora,Ecuador.

BUTLER,R.W.(1980).theConceptofaTouristAreaCycleofEvolution:ImplicationsforManagementofResources.TheCanadianGeographer/LeGéographecanadien,24(1),5–12.[doi:10.1111/j.1541-

http://jasss.soc.surrey.ac.uk/17/1/14.html 10 15/10/2015

0064.1980.tb00970.x]

CECCHINI,A.,&Trunfio,G.A.(2007).AMultiagentModelforSupportingTourismPolicy-MakingbyMarketSimulations.Computationalscience:7thInternationalconference,ICCS2007:proceedings,partI(pp.567–574).NewYork:Springer.[doi:10.1007/978-3-540-72584-8_75]

CROOKS,A.,Castle,C.,&Batty,M.(2008).Keychallengesinagent-basedmodellingforgeo-spatialsimulation.Computers,EnvironmentandUrbanSystems,32(6),417–430.[doi://dx.doi.org/10.1016/j.compenvurbsys.2008.09.004]

EPLER,B.(2007).Tourism,theEconomy,PopulationGrowth,andConservationinGalapagos.CharlesDarwinFoundation,PuertoAyora,ProvinceofGalapagos,Ecuador,(September).

GEN,M.andYu,X.(2010).IntroductiontoEvolutionaryAlgorithms.(R.Roy,Ed.)(second.).NewYork:Springer.

GONZÁLEZ,J.A.,Montes,C.,Rodríguez,J.and,&Tapia,W.(2008).RethinkingtheGalapagosIslandsasacomplexsocial-ecologicalsystem:implicationsforconservationandmanagement.EcologyandSociety,13(2).Retrievedfromhttp://dlc.dlib.indiana.edu/dlc/handle/10535/2456

GRIMM,V.,Berger,U.,Bastiansen,F.,Eliassen,S.,Ginot,V.,Giske,J.,Goss-Custard,J.,etal.(2006).Astandardprotocolfordescribingindividual-basedandagent-basedmodels.EcologicalModelling,198(1–2),115–126.[doi:10.1016/j.ecolmodel.2006.04.023]

GRIMM,V.,Berger,U.,DeAngelis,D.L.,Polhill,J.G.,Giske,J.,&Railsback,S.F.(2010).TheODDprotocol:Areviewandfirstupdate.EcologicalModelling,221(23),2760–2768.[doi:10.1016/j.ecolmodel.2010.08.019]

GRIMM,V.,Revilla,E.,Berger,U.,Jeltsch,F.,Mooij,W.M.,Railsback,S.F.,Thulke,H.-H.,etal.(2005).Pattern-orientedmodelingofagent-basedcomplexsystems:lessonsfromecology.Science(NewYork,N.Y.),310(5750),987–91.[doi:10.1126/science.1116681]

JOHNSON,P.A.,&Sieber,R.E.(2011).Anagent-basedapproachtoprovidingtourismplanningsupport.EnvironmentandPlanningB:PlanningandDesign,38(3),486–504.Retrievedfromhttp://www.envplan.com/abstract.cgi?id=b35148[doi:10.1068/b35148]

LIGTENBERG,A.,VanLammeren,R.J.a.,Bregt,A.K.,&Beulens,A.J.M.(2010).Validationofanagent-basedmodelforspatialplanning:Arole-playingapproach.Computers,EnvironmentandUrbanSystems,34(5),424–434.[doi:10.1016/j.compenvurbsys.2010.04.005]

LIU,J.,Dietz,T.,Carpenter,S.R.,Alberti,M.,Folke,C.,Moran,E.,Pell,A.N.,etal.(2007).Complexityofcoupledhumanandnaturalsystems.Science(NewYork,N.Y.),317(5844),1513–6.[doi:10.1126/science.1144004]

LUKE,S.,Cioffi-Revilla,C.,Panait,L.,Sullivan,K.,&Balan,G.(2005).MASON:Amultiagentsimulationenvironment.Simulation,1–18.Retrievedfromhttp://sim.sagepub.com/content/81/7/517.short[doi:10.1177/0037549705058073]

OBSERVATORIODETURISMOGALAPAGOS.(2011).Boletinn1sept2011.

OSTROM,E.(2007).Adiagnosticapproachforgoingbeyondpanaceas.ProceedingsoftheNationalAcademyofSciencesoftheUnitedStatesofAmerica,104(39),15181–7.[doi:10.1073/pnas.0702288104]

OSTROM,E.(2009).Ageneralframeworkforanalyzingsustainabilityofsocial-ecologicalsystems.Science(NewYork,N.Y.),325(5939),419–22.[doi:10.1126/science.1172133]

PARQUENACIONALGALÁPAGOS(2007).PlanManejoParqueNacionalGalapagos.

PARQUENACIONALGALÁPAGOS.(2012).PNGtouristsstatistics.Retrievedfromhttp://www.galapagospark.org/onecol.php?page=turismo_estadisticas

PIANA,V.(2004).CONSUMERDECISIONRULESFORAGENT-BASEDMODELS.EconomicsWebInstitute.Retrievedfromhttp://www.economicswebinstitute.org/essays/consumers.pdf

PLOG,S.(1974).Whydestinationareasriseandfallinpopularity.CornellHotelandRestaurantAdministrationQuarterly,14(4),55–58.Retrievedfromhttp://www.mendeley.com/research/destination-areas-rise-fall-popularity/[doi:10.1177/001088047401400409]

TRUEMAN,M.,Atkinson,R.,Guézou,A.,&Wurm,P.(2010).Residencetimeandhuman-mediatedpropagulepressureatworkinthealienfloraofGalapagos.BiologicalInvasions,12(12),3949–3960.[doi:10.1007/s10530-010-9822-8]

WATKINS,G.,&Cruz,F.(2007).GALAPAGOSATRISKASocioeconomicAnalysis.CharlesDarwinFoundation,PuertoAyora,ProvinceofGalapagos,Ecuador,(May).

WORLDTOURISMORGANIZATION.(2006).TourismMarketTrendsWorldOverview&TourismTopics.

YIN,L.(2007).AssessingIndirectSpatialEffectsofMountainTourismDe-velopment:anApplicationofAgent-basedSpatialModeling.TourismandRegionalScience,37(3),257–265.Retrievedfromhttp://jrap-journal.org/pastvolumes/2000/v37/F37-3-8.pdf

AppendixA:DataTables

Table2:Parametersdefiningthearchipelagograph.Islandsmarkedwithan"h"areentrancehubstothearchipelago.*Datafromfieldsurveys

Connection Price(USD)* Time(hours)*SantaCruzh-SanCristobalh 30 2.5

SantaCruzh-Isabela 30 2.5

SantaCruzh-Floreana 30 2.5

Table3:NumberoftouristicattractionsassociatedwiththeArchipelago'sIslandsandtheircruises.*DatafromGalapagosNationalPark

Island Numberoftouristicattractions*SantaCruz 17SanCristobal 12Isabela 16Floreana 7Cruises 18

Table4:Firstpartofthetouristagent'sstatevariables1thevaluesreportedinthistablemustbedecreasedby$560.00(USD)forforeigntouristandby$366.00(USD)forEcuadoriantourists

http://jasss.soc.surrey.ac.uk/17/1/14.html 11 15/10/2015

Table5:Valuesofthefivedimensionsofthetouristagent'scharacterstatevariable

Table6:Thefivedimensionsoftheaccommodationoffersfeaturestatevariable

http://jasss.soc.surrey.ac.uk/17/1/14.html 12 15/10/2015

Table7:Statevariablesofthemarketoperatoragent

http://jasss.soc.surrey.ac.uk/17/1/14.html 13 15/10/2015

Table8:InvestmentcostsparametersforHotels.Datafromfieldsurvey

Category AB(m

2) P

m

2(USD) α

First 30 800 100Second 23 700 50Third 15 600 10Fourth 8 400 0

Table9:InvestmentcostsparametersforCruises.Datafromfieldsurvey

Category αI(USD)

Luxury 156250First 143750Medium 131250Economy 118750

Table10:OperationexpensesparametersforHotels.Datafromfieldsurvey

Table11:OperationexpensesparametersforCruises.Datafromfieldsurvey.

>

Table12:Statevariablesofthetouristagentgenerator

Variable Description ValuesPeriodicity DefinethetimeschedulingoftheAgent dailyNumbertouristagentsperyear

Definethenumberoftouristagentgeneratedeverysimulationyear 200000(tourist)

Numberofbudgetclass Definethenumberclassesinwhichthegeneratedtouristagentswillbedividedusingtouristagentbudgetascriterion

7

Numberofageclasses Definethenumberclassesinwhichthegeneratedtouristagentswillbedividedusingtouristagentage 3

http://jasss.soc.surrey.ac.uk/17/1/14.html 14 15/10/2015

ascriterionSeasonaltuning Changethenumberofgeneratedtouristagentdependingonthemonthoftheyear FromGalapagosNationalPark

Statistics

http://jasss.soc.surrey.ac.uk/17/1/14.html 15 15/10/2015