probable capture fisheries scenarios for danajon...

Probable Capture Fisheries Probable Capture Fisheries Scenarios for Scenarios for DanajonDanajon BankBank

Input to the Formulation of the Input to the Formulation of the DanajonDanajonBank Fisheries Management PlanBank Fisheries Management Plan

29 June 200529 June 2005

TopicsTopics

TrophicTrophic system system –– the conceptthe conceptData inputsData inputsTrophicTrophic system for system for DanajonDanajon BankBankScenarios and simulationScenarios and simulationSummarySummary

Trophic level: the concept Trophic level: the concept Trophic level: the concept Tr

ophi

c le

vel

Trop

hic

leve

l

PhytoplanktonPhytoplankton

Top predatorsTop predators

Prey fishPrey fish

ZooplanktonZooplankton

. . . . . . .... .. .. .. .. .. .. .. *.*. .. .. ... . ..*.*.*.*.*.*.

*.*. *.*.*.*.*.*.

≅ 10%≅ 10%

≅ 10%≅ 10%

≅ 10%≅ 10%

*.*.

44

33

22

11

Ecology of fisheriesEcology of fisheriesEcology of fisheriesFisheries form part of a complex ecosystem

Fisheries Fisheries form part of a form part of a complex complex ecosystemecosystem

Some data inputSome data input

TrophicTrophic group group -- BiomassBiomassConsumption to biomass ratioConsumption to biomass ratioRate of mortalityRate of mortalityEcotrophicEcotrophic efficiencyefficiencyDiet compositionDiet compositionFishery harvestFishery harvestGate pricesGate prices

TrophicTrophic groupsgroups

danggitdanggit, , kitongkitong, , samaralsamaralRabbitfishRabbitfish1313banakbanak, , gisawgisaw, , molmolmolmolDemersalDemersal herbivoresherbivores1212gunoguno, , bolinaobolinao, , libgaolibgao, solid, solidCoastal Coastal planktivoresplanktivores1111

nokosnokos tarorotontaroroton, , bisayabisaya, , kubotankubotan, , bukobuko--bukobukoSquidsSquids44

1414

1010998877

66

55

332211

uyapuyapSergestidsSergestids

hiloshilos--hiloshilos, , mangsimangsi, , gilanggilang, , maubgasmaubgasSardinesSardinestamarongtamarong, , tikabtikab, , anduhawanduhawPelagic Pelagic planktivoresplanktivorespasayanpasayan, , loconlocon, , lunhanlunhan, , bulitbulitShrimpsShrimpslambaylambay, , kasagkasagBlue crabsBlue crabs

pakolpakol, , ngisingisi--ngisingisi, , kyampawkyampaw, , liptilipti, , labayanlabayan, , lupitlupit, , katambakkatambak, , tad, tad, lagawlagaw, , tuwastuwas, , silaysilay

ReefReef--associated associated zoobenthoszoobenthos feedersfeeders

moongmoong, , sapsapsapsap, , caraballascaraballas, , samooksamook, , bogobogo, , timbungantimbungan, , asoosasoos, , bugaongbugaong

SoftSoft--bottom bottom zoobenthoszoobenthosfeedersfeeders

ahaanahaan, , islawanislawan, , awmanawman, , panangitanpanangitan, , gawotgawot, , pugapopugapoReefReef--associated associated piscivorespiscivoresubodubod, , tikitiki--tikitiki, , sunugansunugan, , banghutinbanghutinSoftSoft--bottom bottom piscivorespiscivoresbawobawo, , talakitoktalakitok, , kubalkubal--kubalkubal, , balilabalila, bat, bat--ogog, lapis, , lapis, tangigitangigi, , diwitdiwitPelagic Pelagic piscivorespiscivores

Diet compositionDiet composition

mangsi, maubgas

0 10 20 30 40 50 60

M ollusks

Other benthic crustaceans

Coastal planktivores

Shrimps

Zooplankton

Phytoplankton

potpot, timbungan, buagaong

0 5 10 15 20 25

Reef zoobenthos feeders

Echinoderms

Soft-bottom zoobenthos feeders


Phytoplankton

Sergestids

M ollusks

Other benthic crustaceans

Zooplankton

Algae, seaweeds

Shrimps

Crabs

Detritus

Worms

(percent composition of food group)

Harvest estimatesHarvest estimatesHarvest estimates

Gillnets

Blast f ishing

Seine nets

Pots and Traps

Spears

Hook & lines

Traw ls

Impounding nets

Others

Jigs

Other f ine mesh

41.7%

15.9%

10.7%

8.8%

8.7%

6.8%7.5%

(Based on catch survey in the focal of Danajon Bank)

Gate priceGate price

55OctopusOctopus1010SergestidsSergestids1313Other crabsOther crabs1919Coastal Coastal planktivoresplanktivores2424SardinesSardines3131SoftSoft--bottom bottom piscivorespiscivores4343SoftSoft--bottom bottom zoobenthoszoobenthos feedersfeeders6060Pelagic Pelagic planktivoresplanktivores6060Pelagic Pelagic piscivorespiscivores6262ReefReef--associated associated zoobenthoszoobenthos feedersfeeders6565RabbitfishRabbitfish7676SquidsSquids8080DemersalDemersal grazers/herbivoresgrazers/herbivores

117117Blue crabsBlue crabs130130ReefReef--associated associated piscivorespiscivores163163ShrimpsShrimps

Pesos/kiloPesos/kiloFish groupFish group

1919ScoopnetScoopnet2626dynamitedynamite2828beach seinebeach seine3131round haul seineround haul seine3333multiple multiple handlinehandline3636stationary stationary liftnetliftnet3636drift gillnetdrift gillnet3838encircling gillnetencircling gillnet4040set gillnet with plungerset gillnet with plunger4646danishdanish seineseine5454simple hook and linesimple hook and line5656bottom set gillnetbottom set gillnet6262trammel nettrammel net6464drivedrive--in gillnetin gillnet6666bottom set bottom set longlinelongline6767fish trapfish trap7474fish corralfish corral7777handspearhandspear7878spear with compressorspear with compressor8080squid jigsquid jig8080hook and line with floathook and line with float9999otter trawlotter trawl9999crab crab liftnetliftnet

118118crab gillnetcrab gillnet118118crab potcrab pot

Pesos/kiloPesos/kiloFishing gearFishing gear

Fishes

Fishing gears

Focal area in Focal area in DanajonDanajon BankBank

Area: 1,227 km2

pasayan(shrimps)

lambay, kasag(crabs)

banak, gisaw(algal grazers, herbivores)

bawo, talakitok, tangigi(pelagic piscivores)

ahaan, awman, pugawo(reef piscivores)

Trop

hic

leve

l

1

2

3

4

potpot, moong, timbungan

(soft-bottom zoobenthosfeeders)mangsi, gilang

maubgas (sardines)

bolinao, guno(coastal planktivores)

AlgaeDetritusPhytoplankton

Zooplankton

Trophic structure of Danajon Bank ecosystem

TrophicTrophic structure of structure of DanajonDanajon Bank Bank ecosystemecosystem

Average trophic level of the fishery: 2.89Average Average trophictrophic level of the fishery: 2.89level of the fishery: 2.89

pasayan(shrimps)





Trop

hic

leve

l

1

2

3

4



maubgas (sardines)



Zooplankton




0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5


Blue crabs

Sardines

Pelagic piscivores

Reef-assoc. zoob. feeders


Squids

Pelagic planktivores

Shrimps

Rabbitf ish

Demersal grazers/herbiv.

Reef-associated piscivores

Soft-bottom piscivores

Octopus

Other crabs

Sergestids

Total harvestable biomass

harvestable biomass (t/km2/yr)

Total harvestable biomass: 3.32 t/km2

Biomass estimates (initial year)Biomass estimates (initial year)Biomass estimates (initial year)

shrimps: 0.76 t/km2

other crabs: 0.59 t/km2

soft-bottom zoob.feeders: 0.42 t/km2

sardines: 0.32 t/km2

blue crabs: 0.22 t/km2

Top predators?

Equivalent value: PhP 237,581/km2

Value for focal area: PhP 291 Million

Trophic level: the concept Trophic level: the concept Trophic level: the concept Tr

ophi

c le

vel

Trop

hic

leve

l

PhytoplanktonPhytoplankton

Top predatorsTop predators

Prey fishPrey fish

ZooplanktonZooplankton

. . . . . . .... .. .. .. .. .. .. .. *.*. .. .. ... . ..*.*.*.*.*.*.

*.*. *.*.*.*.*.*.

≅ 10%≅ 10%

≅ 10%≅ 10%

≅ 10%≅ 10%

*.*.

44

33

22

11

SimulationSimulation

AA Increase of trawls, Danish seines, Increase of trawls, Danish seines, and blast fishing activitiesand blast fishing activities

Collapse of Collapse of management regimemanagement regime

BB Removal of all illegal and Removal of all illegal and destructive gears and effort destructive gears and effort redistributed indiscriminatelyredistributed indiscriminately

Partial/haphazard Partial/haphazard management management interventionsinterventions

CC Removal of all illegal and Removal of all illegal and destructive gears and effort destructive gears and effort redistributed appropriatelyredistributed appropriately

Appropriate Appropriate management options management options in place in place

-5%

0%

5%

10%

15%

20%

25%

30%

0 1 2 3 4 5 6

Year

% c

hang

e in

bio

mas

s

No management

Partial management

Sound management

Trend in harvestable biomass in the years Trend in harvestable biomass in the years following interventionfollowing intervention

Value (in Value (in PhPPhP) of harvestable biomass in the ) of harvestable biomass in the years following interventionyears following intervention

-5.0%

5.0%

15.0%

25.0%

35.0%

0 1 2 3 4 5 6

Partial management

Sound management

No management

-5%

0%

5%

10%

15%

20%

25%

30%

0 1 2 3 4 5 6

Year

% c

hang

e in

bio

mas

s

No management


No managementNo managementNo management

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8


Blue crabs

Sardines

Pelagic piscivores



Squids


Shrimps

Rabbitfish




Octopus

Other crabs

Sergestids

2005 2007 2010

-- 7%7%-- 4%4%ShrimpsShrimps-- 25%25%-- 18%18%RabbitfishRabbitfish-- 23%23%-- 19%19%Pel.pisciPel.pisci..-- 65%65%-- 40%40%OctopusOctopus-- 66%66%-- 54%54%SardinesSardines2010201020072007GroupGroup

3.28 t/km3.28 t/km223.35 t/km3.35 t/km22Overall Overall harvestable harvestable biomassbiomass

-- 1.4%1.4%+ 0.8%+ 0.8%% change% change

2010201020072007

+14 %+14 %+ 14%+ 14%SoftSoft--bottom bottom zoob.feedzoob.feed..

+ 25%+ 25%+ 23%+ 23%Blue crabsBlue crabs+ 16%+ 16%+ 17%+ 17%Coast.plankCoast.plank..+ 13%+ 13%+ 16%+ 16%Other crabsOther crabs

2010201020072007GroupGroup

-5%

0%

5%

10%

15%

20%

25%

30%

0 1 2 3 4 5 6

Year

% c

hang

e in

bio

mas

s

Partial management


0.00 0.25 0.50 0.75 1.00 1.25


Blue crabs

Sardines

Pelagic piscivores



Squids


Shrimps

Rabbitfish




Octopus

Other crabs

Sergestids

2005 2007 2010 Partial managementPartial managementPartial management

+ 53%+ 53%+ 35%+ 35%ShrimpsShrimps+ 97%+ 97%+ 97%+ 97%RabbitfishRabbitfish

+ 135%+ 135%+ 124%+ 124%Reef Reef piscipisci..+ 136%+ 136%+ 134%+ 134%PelPel. . PisciPisci..

+ 133%+ 133%+ 120%+ 120%OctopusOctopus+ 120%+ 120%+ 105%+ 105%SoftSoft--bottom bottom

piscipisci..+ 117%+ 117%+ 102%+ 102%SquidsSquids

2010201020072007GroupGroup


+ 25.1%+ 25.1%+ 21.3%+ 21.3%% change% change

2010201020072007GroupGroup

-- 19%19%-- 15%15%SergestidsSergestids-- 90%90%-- 69%69%PelPel. Plank.. Plank.-- 75%75%-- 69%69%Blue crabsBlue crabs2010201020072007GroupGroup

-5%

0%

5%

10%

15%

20%

25%

30%

0 1 2 3 4 5 6

Year

% c

hang

e in

bio

mas

s

Sound management


0.0 0.2 0.4 0.6 0.8 1.0


Blue crabs

Sardines

Pelagic piscivores



Squids


Shrimps

Rabbitfish




Octopus

Other crabs

Sergestids

2005 2007 2010


+ 17.3%+ 17.3%+ 18.0%+ 18.0%% change% change

2010201020072007Sound managementSound managementSound management

-- 18%18%-- 10%10%ReefReef--assoc. assoc. zoobzoob. Feeders. Feeders

-- 100%100%-- 95%95%Pelagic plank.Pelagic plank.2010201020072007GroupGroup

+ 59%+ 59%+ 54%+ 54%ReefReef--assoc. assoc. piscivorespiscivores

+ 26%+ 26%+ 23%+ 23%CrabsCrabs

+ 129%+ 129%+ 124%+ 124%SquidsSquids+ 121%+ 121%+ 127%+ 127%PelPel. . PisciPisci..

+ 80%+ 80%+ 80%+ 80%RabbitfishRabbitfish+ 78%+ 78%+ 77%+ 77%SoftSoft--bottom bottom

piscivorespiscivores+ 60%+ 60%+ 65%+ 65%SardinesSardines

+ 162%+ 162%+ 143%+ 143%OctopusOctopus2010201020072007GroupGroup

SummarySummary

Collapse of management regime will lead to Collapse of management regime will lead to overall decline of the harvestable biomassoverall decline of the harvestable biomassPartial management will lead to the biggest Partial management will lead to the biggest overall increase in the harvestable biomass but overall increase in the harvestable biomass but drastic decline of important commodity like the drastic decline of important commodity like the “blue crab”“blue crab”Sound management will lead to a moderate Sound management will lead to a moderate increase in the harvestable biomass but increase in the harvestable biomass but increase in the desirable species especially the increase in the desirable species especially the carnivorescarnivores

Thank youThank you

probable capture fisheries scenarios for danajon...

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