AquacultureorthefarmingofaquaticplantsandanimalsisanimportantfisheriesindustryinthePhilippines. In2015,aquaculturecontributed50%ofthetotal fisheriesproductionof thecountrywithavalueof85billionpesos (PSA,2016). ThemainPhilippineaquacultureproductsareseaweeds(67%),milkfish(16%),andtilapia(11%).

Globalwarmingor climate change impactsonaquatic systems. From theassessmentreport of the Intergovernmental Panel onClimateChange, theocean’smean temperatureof0.11oCperdecadefrom1971to2010,whilethemeansealevelroseby1.7mm/yrfrom1901to2010andthefrequencyofintensecyclonesincreased(SeggelandDeYoung,2015).

NAST Bulletin No. 11 PublishedbytheNational Academy of Science and Technology, Philippines (NAST PHL) February2017A contribution from the Agricultural Sciences Division of NAST PHL.

About the Author:

Academician Rafael D. Guerrero isamemberoftheNationalAcademyofScienceandTechnology,Philippines(NASTPHL)andanAdjunctProfessorattheUniversityofthePhilippinesLosBaños,SchoolofEnvironmentalScienceandManagement.HeholdsaPhDinFisheriesManagementfromAuburnUniversity,Alabama,USA.HeistheformerExecutiveDirectorofthePhilippineCouncilforAquaticandMarineResearchandDevelopmentoftheDepartmentofScienceandTechnology.

NASTPHListhecountry’spremieradvisoryandrecognitionbodyonscienceandtechnology.NASTPHLisanattachedagencytotheDepartmentofScienceandTechnology.(www.nast.ph;email:secretariat@nast.ph)

COPING STRATEGIES FOR CLIMATE CHANGE IMPACTS ON PHILIPPINE AQUACULTURE

Rafael D. Guerrero IIINational Academy of Science and Technology Philippines (NAST PHL)

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Fishpens and floating cages made ofsuspended net enclosures with bamboo poles forsupport and floatation are destroyed by the strongwinds and waves brought about by typhoons. EventhefloatingNorwegian-typecages (Fig.8)withsturdypolyvinylchloride(PVC)andsteelpipesforframesandfloatationwerenotsparedin2010byTyphoons“Mina”and “Pedring” which hit Lingayen Gulf causing lossesamountingtomillionsofpesos(Cardinoza,2011).

Fixed cages are used in shallow lakes while floatingcages, also made of bamboo poles for framing andfloatationwithsuspendednetenclosures,areused indeeplakesandreservoirs.

Freshwater ponds are vulnerable to floodscausedbyheavyrainfallsespeciallyinfloodplainareassuch as that of Central Luzon. Prolonged dry spellsand droughts can also limit fish production with thelackofwaterfromtheirrigationsourceandhighwatertemperatureoftheshallowponds.IntheCagayanValley(Region2),fishfarmershaveexperienced“fishkills”orheavyfishmortalitiesintheirpondsparticularlyinthemonthsofMaytoAugustwhentheairtemperaturecanbeashighas40 oCandtherainyseasonsetsinwhichsubjects the cultured fish to abrupt changes inwatertemperature(Guerrero,2014).

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The El Niňo of 1997-1988 caused by highsurface temperature and drought negatively affectedPhilippine fisheries. As a result of the event, totalfisheriesproductiondecreasedby283,879metrictonsvalued at 72.48million pesos. The aquaculture sub-sector of Philippine fisheries was the most adverselyaffected with 85% of the total economic loss. Thecultureofspeciesinbrackishwaterpondsandseaweedfarms in coastal waters were the most seriouslyimpacted.

Studieshavebeenproposedtoaddressclimatechangethroughmitigationandadaptation.Mitigationreferstoactionsthatcanlowergreenhousegasemissionandsequestercarbon.Adaptation,ontheotherhand,consists of measures or strategies for coping withclimatechangeimpacts.

This studywas done to assess the impacts ofclimatechangeonPhilippineaquaculturewithfocusonthe farming of seaweeds,milkfish and tilapia, and toidentify coping strategies for cushioning such impactsonthecultureofthesaidspecies.

Inassessingthe impactsofclimatechangeonPhilippineaquaculture,informationfromtheliteraturewas gathered and field observations were made. Inidentifyingcopingstrategiesforseaweeds,milkfishandtilapia culture, interviews with reliable persons, fieldobservationsandanexperimentwereconducted.

A. Assessment of Climate Change Impacts on Philippine Aquaculture

(1) Seaweeds The Philippines is one of the world’s biggestproducersoftheredseaweeds,Eucheuma denticulatum andKappaphycus alvarezii (Fig.1),whichareculturedin more than 150,000 hectares of coastal waters inthe country by over 100,000 fisherfolk families. Thecommonmethodsofculturearemonolinesfixedtothebottom(Fig.2)inshallowwaters(0.5-1mdeepatlowtide)andfloatingmonolines (Fig.3) indeeperwaters(morethan1matlowtide).

Whileseaweedsarecapableoftakingupcarbondioxideintheseaforphotosynthesis,theirgrowthandsurvival are reducedbyhigh surface sea temperatureandintenseexposuretosunlightparticularlyinshallowwatersduringthehotweathermonths(MarchtoApril)anddroughtperiods(i.e.,ElNiňo). Theoccurrenceofthe so-called “ice-ice disease” caused by unfavorableenvironmental conditions as high salinity, hightemperature,lackofnutrientsandotherfactors(Largo,2002)isalsoprevalent.

Typhoons have also been destructive toseaweedfarmsinthecountry.SuperTyphoonYolandainNovember2013destroyedmorethan2,000hectaresof the farms in MIMAROPA (Region 4B), the CentralandEasternVisayas (Regions7and8)anddiminishedthelivelihoodsofanestimated16,500coastalfamilies(FAO,2014;Galvez,2014).

(2) Milkfish The milkfish (Chanos chanos) is the mostimportant culturedfish (Fig. 4) in thePhilippines thatis extensively grown in brackishwater ponds (Fig. 5),fishpens (Fig.6) in lakesandtidal rivers,andfloatingcages (Fig. 7) in coastal waters. There are about200,000 hectares of brackishwater ponds, more than10,000hectaresoffishpensandaround5,000hectaresof floating cages used formilkfish culture throughoutthecountry.

Fig.1-Kappaphycus alvarezii Fig.2-Bottom-fixedmonolines(Source:RafaelD.GuerreroIII)(Source:seaglobe.com)

Fig.3-Floatingmonoline(Source:CenterforEmpowermentandResourceDevelopment)

Fig.4-Chanos chanos(Source:FishConsultingGroup)

Fig.5-Brackishwaterponds(Source:www.aq.auburn.edu)

Fig.6-Afishpeninashallowlake(Source:trips2Philippines.com)

Fig.7-Floatingcageinthesea(Source:SEAFDECPhilippines)

Fig.8-Norwegian-typeoffloatingcage(Source:TheFishSite)

(3) Tilapia The Nile tilapia (Oreochromis niloticus) is thesecond most important cultured fish (Fig. 9) in thecountrywithmorethan14,000hectaresoffreshwaterponds(Fig.10)particularlyinCentralLuzonandaround10,000 hectares of fixed (Fig. 11) and floating cages(Fig.12)inlakes(e.g.,LagunadeBayandTaalLake)andreservoirs(e.g.MagatReservoir).

The freshwaterpondsaregenerally shallow (1meterdeep)andsuppliedwithwaterfromanirrigationsourceand/orpumpedundergroundwater.

Fig.9-Oreochromis niloticus(Source:GalaDiscovery)

Fig.10-Freshwaterponds(Source:AquaworldAquarium)

Fig.11-Bottom-fixedcagesinashallowlake(Source:FoodAgriculturalOrganization)

Fig.12-Floatingcagesinadeeplake(Source:YouTube)

B. Coping Strategies for Philippine Aquaculture

(1) Seaweeds A coping strategy practiced by farmers forminimizingtheoccurrenceofthe“ice-icedisease””inseaweedsisgrowingtheplantswithfloatingmonolinesindeepcoastalwatersinsteadofwithfixedmonolinesinshallowwaterstoavoidhighseasurfacetemperatureandintenseexposuretosunlightparticularlyduringthe

hot weather months of April and May. The floatingmonolines (Fig. 13) to which the plants are attachedcanalsobeloweredunderwaterwithweightstofurtherlessen the effects of high surface temperature andintense light. Field tests toverify theeffectivenessofsuchmeasuresagainst the “ice-icedisease,”however,needtobedone.

Another possible coping strategy is theapplication of fertilizers such as the “Ocean Green”(20% ferrous sulfate)at40g/m2/wkwhichwas foundinastudytobecost-effectivewithincreaseintheyieldoffloatingraft-culturedK. alvarezii by30%morethanthatofthecontrolandapparentresistanceto“ice-icedisease”duringthehotweathermonthsofMarch-April(Guerreroetal.,2003).

A powder extract of the brown seaweedAscophythium nodosum found in the North AtlanticandcommerciallyproducedasAMPEP(AcadianMarinePlant Extract Powder) is also said to be effective forenhancinggrowthanddiseaseresistanceofK. alvarezii whenappliedasadipatlowconcentrationsforplantingmaterials(Hurtadoet al.,2015).

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Fig.13-Underwatermonolinesforseaweedculture(Source:stevenreef.com)

(2) Milkfish The coping strategies thatmay be applied tominimize lossoftheculturedspecies inbrackishwaterpondsduringfloodeventsaretoincreasetheheightofponddikes(Fig.14)atleastameterabovethehighestrecordedfloodleveltoforestallwaterovertoppingfromthe outside and/or the installation of net enclosures(Fig.15)alongtheperimetersofthepondstopreventthestockfromescaping.

Toreducefishlossduringdryspellsordroughts,thepondscanbefurtherdeepenedtoholdmorewater(Fig. 16) and a supplemental supply of undergroundwatercanbetappedusingpumps(Fig.17)toaugmentthelowwatersupplyoftidalrivers.

Fig.14-Mechanicalponddikeconstruction(Source:YouTube)

Fig.15-Netenclosuresinapond(Source:SEAFDECAQD)

Fig.16-Mechanicalponddeepening(Source:YouTube)

Fig.17-Undergroundwaterpump(Source:FAO)

The coping strategy applied to prevent theescapeoffishcultured incoastalwaterfloatingcagesduring typhoons is the use of submersible cages.One such innovation is the “rope-framedfloatingfishcage” (RFFC) inRegion1developedby researchersoftheBureauof Fisheries andAquaticResources ledbyRegionalDirectorNestorDomenden. InsteadofusingPVCorsteelpipesforframingandfloatation,theRFFChas a rope frame that is kept afloat by plastic buoys (Fig.18).

TheRFFC ismoreflexible, easier tobuild andcheaper than the rigid, difficult to build and moreexpensiveNorwegian-typeoffloatingcagescommonlyusedbytheindustry.Onlythe20RFFCsofthecompanywhichadoptedtheinnovationremainedintactaftertheseriesoftyphoonsthatstruckLingayenGulfin2010and2011(Cardinoza,2011).ApatentfortheRFFCisbeingappliedfor.

Another submersible floating cage design formilkfish culturehasbeen introducedby the JapaneseInternationalCooperationAgency(JICA)inthecountryparticularly to replace the conventional cages withbamboo frames which were destroyed by SuperTyphoonYolandainSamarandLeyte(JICA,2016).Thenewcagedesignuseshighdensitypolyethylene(HDPE)pipesforframesandfloatationwhichissaidtobe

CopingStrategiesforClimateChangeImpact.......p.5

resistanttostrongwaves.Withasystemofweights,theJapanese-designedcagecanbeloweredunderwatertoavoidthesurfacewindandwaveforces(Fig.19).

Fig.18-Rope-framedfloatingfishcage(Source:TigerPropertyDevelopersGroup,Inc.)

Fig.19-Japanese-designedsubmersiblefloatingcage(Source:JICA)

(3) Tilapia The coping strategies for freshwater pondculture of the Nile tilapia in addressing floods anddroughtsaresimilartothoseforbrackishwaterponds.Increasing theheightofponddikes,deepeningpondsfrom1to2meterstoincreasewatervolume,useofnetenclosuresandsupplementingwatersupplybymeansof pumps are also appropriatemeasures that can beapplied.

Theuseoffine-meshnets(Fig.20)forshadingsimilartothatforprotectingplantssensitivetosunlightinagriculturehasbeendonebysomefishpondoperatorsinthecountrytolessenpondwatertemperature.Thecost of such practice, however, can be prohibitive forlargepondsandneedstobeevaluated.

In a field study conducted by the author in afishfarm in Bay, Laguna inMarch-April 2016, the useofwater lettuce (Pistia stratiotes), a floating aquaticweed, was tested to determine its effectiveness asshadeplant to reducewater temperatureof fertilizedfreshwater ponds and its effect on the growthof theblack-chin tilapia (Sarotherodon melanotheron). Theresultsshowedthattheuseoftheplant(Fig.21)whichwas contained at the pond surface with floating PVCpipesloweredpondwatertemperatureby3.2oCwith24%shadingof thepondcompared to33.8 oC of the controlpond (without shading). Thefish in thepondwith24%shadinggrewattherateof0.59g/daywhile

thoseinthepondwithonly12%shadingandwithpondwatertemperatureonly1.5oC lesser thanthatof thecontrolpondhada-0.12g/daygrowthrate. Thecostofshading24%ofthesurfaceofa200m2pondusing5cmdiameterPVCpipestocontainthefloatingplantwasPhP4,500.

Fig.20-Fine-meshnetshadingofapond(Source:BFARRegion1)

Fig.21-Shadingofafreshwaterpondwithwaterlettuce(Source:RafaelD.GuerreroIII)

InshallowlakeslikeLagunadeBay,submersiblefixedcages(Fig.22)havebeenusedforthecultureoftheNiletilapiabyfarmersformanyyearstominimizethe lossofthefishduringtyphoonevents. Thecagesare simply held down below the water surface withweightswhenwindsandwavesarestrongandbroughtupagaintothesurfacewhentheweatherimproves.

Recommendations

Thereisaneedtoevaluatetheefficiencyandcost-effectiveness of using underwater monolinesand fertilizers for seaweed culture and net shadingfor pond culture of Nile tilapia as coping strategiesto minimize the impact of high water temperature.Further studies on the use of floating aquatic plantsfor shading freshwater pond for fish culture are alsorecommended.

Fig.22-Submersiblebottom-fixedcageinLagunadeBay(Source:RafaelD.GuerreroIII)

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References

Cardinoza,G. 2011.Weather-proof fish cages seen assaviorofaquacultureindustry.PhilippineDailyInquirer,November1,2011.

Food and Agriculture Organization. 2014. HelpingseaweedfarmingflourishaftertyphoonhitsPhilippines(www.fao.org/in-action/helpingseaweedfarming...)

Galvez,J.K.2014.Yolandavictimstogetseaweedfarmtools.TheManilaTimes,October14,2014.e

Guerrero, R.D. III, K. Hotta and L.A. Guerrero. 2003.Useof“OceanGreen” for thecultureofKappaphycus alvarezii in the Philippines. Asia Life Sciences,12(1):39-43.

Guerrero,R.D.III.2014.TilapiafarmerscopewithclimatechangeinIsabela.AgricultureMonthly,XVIII(4):18-19.

Hurtado,A.Q.,R.P.Reis,R.R.LoureiroandA.T.Critchley.2015.Kappaphycus(Rhodophyta)Cultivation,ProblemsandtheImpactofAcadianMarinePlantExtractPowder.In:L.Pereira,J.P.PatricioandJ.M.Neto(eds.)“MarineAlgae–Biodiversity, Taxonomy, Environment” SciencePublishers-CRCPress,USA.251-299.

Japanese International Cooperation Agency. 2016.Japan’stechnologieshelprevivalofmilkfishandoysterfarming in Yolanda-affected areas in the Philippines.(www.jica.go.jp/english/news/field/2015)

Largo, D.B. 2002. Recent developments in seaweeddiseases, pp.35-42. In: Hurtado, A.Q., N.Q. Guanzon,Jr., T.R. de Castro-Mallare and Ma. R.J. Luhan (eds.)Proceedings of the National Seaweed PlanningWorkshop, Southeast Asian Fisheries DevelopmentCenter Aquaculture Department, Tigbauan, Iloilo,Philippines.

PhilippineCouncilforAquaticandMarineResearchandDevelopment.1999.AssessmentofimpactsofElNiňoonPhilippinefisheries.In:ProceedingsoftheNationalWorkshopontheAssessmentofImpactsofElNiňoonPhilippineFisheries.PCAMRD,LosBaňos,Laguna.

PhilippineStatisticsAuthority.2016.FisheriesStatistics2015.QuezonCity,Philippines.

Seggel, A. and C. De Young. 2016. Climate changeimplications for fisheries and aquaculture: summaryoffindingsof the IntergovernmentalPanelonClimateChang Fifth Assessment Report. FAO Fisheries andAquacultureCircularNo.1122.Rome,Italy.54p.

Acknowledgment

The author gratefully acknowledges theResearchFellowshipGrantoftheNationalAcademyofScienceandTechnology,Philippinesfortheconductofthestudy.

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