Some advantages of MPAs for fisheries

ColinA(woodMarineResearchIns4tute

DepartmentofBiologicalScienceUniversityofCapeTown

The Schaefer produc:on model

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Modelparameters:r=0.4y-1,K=100000t

HolyGrail

How do fishery dynamics alter with MPAs?

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MPAmodelparameters:r=0.4y-1,MPAscover20%ofarea,Effortdisplacementincluded,Movementmimicsresidentfishwithbroadcastspawning

cost

Think of a fishery in your area, and :ck the correct boxes.

1) Isthereaneffec4vecatchmonitoringsystem?2)Istherearobustassessmentprocedure?3)Isthereareliableobserversystem?4)Iscompliancewithregula4onsgood?5)Istheadministra4oncorrup4on-free?

Yes No

Yes No

Yes No

Yes No

Yes No

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HolyGrail

If you :cked no for one or more ques:ons, your fishery could end up here (if it is not here already).

Some:mes (very, very seldom) scien:sts get it wrong.

Mysterious New Whale Species Discovered in Alaska

Insurance quote

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Premium

Cover

Annual costs of insurance

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Howmuchshouldwepayhere?

Regula:on by TAC and effort control have some limita:ons.

Most types of fishing gear catch several species of fish at once, other than the one targeted

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These other species are usually less produc:ve. What happens to catches of these species when we reach for

the Holy Grail?

?

?

R.I.P.

Fisheries assessment is easy at high la:tudes, but difficult in the tropics. Why?

1.  Thenumberofspeciesincreasesdrama4callyfrompoletoequator,buttheabundancesdiminish.Weneedtodomoreassessmentsinthetropics,yetthefinancialincen4veislessforeachspecies.Of±600exploitedfishspeciesinSA,16areassessed!

2.  Withsomanysimilartropicalspecies,thereisgreattaxonomicconfusion,andcatchrecordsarenotreliablyassignedtospecies.

3.  Seasonalsignalsareweakornon-existent,sowestruggletoreadthebandsintheotoliths,andtofollowcohorts.Wedonotknowthefish’svitalrates,suchasgrowthandmortality,andtheage-at-maturity.Theseareimportantparametersthatinfluenceproduc4vity.

MPAsareespeciallyusefulinthetropics!

Problem

Fisheries assessments are difficult in the tropics.

AND

Tropical countries have the worst governance and the weakest scien:fic capacity.

Modernfishingintensitypresentsamassiveselec4onpressureagainstpar4culartraits.Manyoftheseareheritable.

Farmers select the best strains for breeding

Farmersimprovetheirstock

Fishing does the opposite

Wekillthestrongandleavetheweaktobreed.Intensefishingweakenstheproduc4vityofthestock.Fishingalsoquicklyreducesgene4cvariability.Gene4cvariabilityisafundamentalrequirementforDarwinianselec4onandadapta4onin4mesof(climate)change.Ul4mately,fishproduc4ondependsongene4cvariability.MPAsarethebestmeanstomaintainnaturalselec4onpressuresandtopreservegene4cvariability.

MPAs can provide substan:al benefits to most of the world’s fisheries