duurzame vis hoe gaat het met de visbestanden? 16 januari, jan jaap poos (imares)

Duurzame vis

Hoe gaat het met de visbestanden?

16 Januari, Jan Jaap Poos (IMARES)

2048

Text slide

3

Global loss of species from Marine Ecosystems

Worm et al 2006 in Science

Cumulative

Annual

“There will be a point in the future where we will run out ...”

Commentaren op “2048” schatting

Branch 2008 in Marine Policy

“[...] even if all fisheries collapsed at least once, 50–55% would be recovered in any given year.”

Hilborn and Branch 2013 in Nature

It is misleading to use catch data to assess the health of fish stocks

Hoe gaat het met de visbestanden?

Analysis of “2048” in scientific literature

Wat zijn dan de regels?

Hoe gaan we daar in Europa mee om?

Froese and Proelss 2010 in fish and Fisheries

“[...] if European Governments are serious about meeting their obligations to [...] the Johannesburg Plan of Implementation[...] they will have to reduce drastically fishing pressure and halt fishing completely on some of the European stocks.

CFPVisserijbeleid in Europa geformuleerd in Common Fisheries Policy. De regels voor beheer van visbestanden in Europa

Population models, MSY &

overfishing

Generiek populatiemodel

Population

Growth

Recruitment

Natural Mortality

Fishing+ -

0 5 10 15 20 25 300

0.2

0.4

0.6

0.8

1

1.2

Generiek populatiemodel

Time

Bio

mass

Exponentiele groei

Dichtheidsafhankelijke groei en sterfte

Generiek populatiemodel

Carrying capacity K, Bmax

0 5 10 15 20 25 300

0.2

0.4

0.6

0.8

1

1.2

Bio

mass

Time

2BK

rrB=

dt

dB

K

BrB

dt

dB1

B = population biomasst = timer = intrinsic population growth rateK = carrying capacity

Generiek populatiemodel

0 5 10 15 20 25 300

0.2

0.4

0.6

0.8

1

1.2

Time

Bio

mass

Carrying capacity

Maximum population growth

Generiek populatiemodel

Carrying capacity K

0 5 10 15 20 25 300

0.2

0.4

0.6

0.8

1

1.2

Bio

mass

Time

Max population growth

2BK

rrB=

dt

dB

We know population growth:

At what biomass do we find maximum growth?

Generiek populatiemodel

0 5 10 15 20 25 300

0.2

0.4

0.6

0.8

1

1.2

Time

Bio

mass

Carrying capacity

Maximum growth

Generiek populatiemodel

Biomass

Popu

lati

on

gro

wth

Max population growth

0 0.2 0.4 0.6 0.8 10

0.91.82.73.64.55.46.37.28.1

99.9

K

Van populatie groei naar surplus productie

Y

B = population biomasst = timer = intrinsic population growth rateK = carrying capacityY = Yield (also called catches)

growthmortality Yield

2BK

rrB=

dt

dB

Biomass

Popula

tion g

row

th

Max pop growth

0 0.2 0.4 0.6 0.8 10123456789

10

Schaeffer model

Populatie in evenwicht als Yield = groei

Y2BK

rrB=

dt

dB

Biomass

Popula

tion g

row

th

Max pop growth

0 0.2 0.4 0.6 0.8 10123456789

10YBK

rrB=

20

2BK

rrB=Y

= maximum surplus

=Maximum sustainable yield

Visserij druk

Y

B = population biomassY = Yield (also called catches)q = catchabilityE = fishing effort

2BK

rrB=

dt

dB

Biomass

Popula

tion g

row

th

0 0.2 0.4 0.6 0.8 10123456789

10

qEBBK

rrB=

dt

dB

2

0 0.2 0.4 0.6 0.8 10123456789

10

Yield

Fishing effort

Eindresultaat: de yield curve

0 0.2 0.4 0.6 0.8 10

0.51

1.52

2.53

3.54

4.55

5.56

6.57

7.58

8.59

9.510

Yield

Fishing effort (or fishing mortality)

Eindresultaat: de yield curve

0 0.2 0.4 0.6 0.8 10

0.51

1.52

2.53

3.54

4.55

5.56

6.57

7.58

8.59

9.510

Yield

Fishing effort (or fishing mortality)

FMSY

costsFisheries “want”

to go here

FMEY

“Yield curves” voor visgemeenschappen

25

Worm et al. 2009 in Science

biodiversity is maintained at low exploitation rate, maximum catch is maintained at intermediate exploitation rate, and high employment is often maintained at intermediate to high exploitation rate”

Where do we stand

26

So where do we stand?

27

Worm et al. 2009 in Science

Global analysis of 166 stocks

For 63% of the examined stocks biomass has dropped below the traditional single-species management target of MSY, that is, B < BMSY. About half of those stocks (28% of total) have exploitation rates that would allow for rebuilding to BMSY

Hoe gaat het in Europa?

28

Fernandes and Cook 2013 in Current Biology

Analyse visbestanden NO AtlanticA) Pelagische vis (haring, makreel, sprot, ...)B) bodemvis (schelvis, koolvis, wijting, ...) C) platvis (schol, tong, heilbot, ...);D) kabeljauwbestanden.

Wat is het effect van verlaging visserijdruk?

29

Fernandes and Cook 2013 in Current Biology

Afname visserijdruk, toename biomassas

Situatie is anders in de Middellandse zee

Vasilakopoulos et al. 2014 in Current Biology

[...] the CFP has not succeeded in improving the state of European Mediterranean commercial fish stocks over the past two decades

“data limitations, low levels of compliance, and poor enforcement”

Visserijdruk Biomassa

Economy

Wat kan er mis gaan: beheerscyclus

onderzoek:Dynamiek van• visbestanden• Ecosystemen

visserij:• vangsten• Inspanning• Aanpassen aan

beheer

beheer:• reguleren• implementeren

advies

Gegevens

regels

Plaice: landings

0

50

100

150

200

1977 1982 1987 1992 1997

Th

ou

sa

nd

to

nn

es

official estimated

Plaice

0

50

100

150

200

1977 1982 1987 1992 1997

Th

ou

sa

nd

to

nn

es

recommended agreed

visserij:

beheer:

onderzoek: incorrect

assessment Plaice Sub-area IV (North Sea)

0

50

100

150

200

250

300

350

400

450

500

1980 1985 1990 1995 2000 2005

SSB ('000 tonnes)

Wat kan er mis gaan: beheerscyclus

De CFP (en certificering)

33

De Common Fisheries Policy

34

Environmentally sustainability while achieving economic, social and employment benefits

Apply the precautionary approach The maximum sustainable yield exploitation rate shall be achieved by 2015 where possible and at the latest by 2020 for all stocks

implement the ecosystem-based approach to minimize negative impacts of fishing on the marine ecosystem

Laatste hervorming CFP in 2013

35Uit Smith 2013 in Current Biology

Certificering

36

MSC

RFS

Viswijzer

Friends of the Sea

Waddengoud

Marine Stewardship Council

37

MSC Fisheries standard

MSC chain of custody standard

Third party certification

Reviewing standards

Principle 1: sustainable fish stocksFishing activity must be at a level which ensures it can continue indefinitely

Principle 2: Minimising environmental impact

Fishing operations must be managed to maintain the structure, productivity, function and diversity of the ecosystem

Principle 3: Effective management The fishery must comply with relevant laws and have a management system that is responsive to changing circumstances

Marine Stewardship Council

MSC Fisheries standard

MSC chain of custody standard

Third party certification

Reviewing standards

Also the MSC label is hotly debated:

Jacquet et al. 2010 in nature

“The MSC is growing rapidly; the organization is also rapidly failing on its promise.”

“In our view, the certification system creates a potential financial conflict of interest, because certifiers that leniently interpret existing criteria might expect to receive more work and profit from ongoing annual audits.”

Kaiser and Hill 2010 in Nature

“We believe that the MSC process has refocused the behaviour and attitudes of fishermen in these areas, and has delivered conservation benefits more effectively than formal non-participatory legislation would have.”

Thank you