The Common Fisheries PolicyState of Resources and Ecosystems

Rainer Froese, GEOMAR, Germany10 December 2014

Sustainable Fisheries Internal SeminarS&D PECH Working Group

Overview

• Revisiting MSY, Fmsy, Bpa and Bmsy

• State of Resources• State of the Ecosystems• Rebuilding stocks above MSY-Level• Minimizing the Impact of Profitable Fishing• Summary

Revisiting MSY, F, Fmsy, Bpa and Bmsy

• MSY is the maximum catch that a stock can deliver long-term

• Bmsy is the biomass that can produce MSY

• Bpa is the biomass below which recruitment may be compromised

• F is the fraction of the fish (present during the year) that are caught

• Fmsy is the F that leads to MSY and Bmsy, albeit in infinite time

Management Framework

0 100 200 300 400 500 6000

200

400

600

800

1000

1200

Spawning stock size

Rec

ruit

s

cons

tant

recr

uit-p

er-s

paw

ner r

atio

SSBlimconstant recruitmentBpa

Outside safebiological limits

proxyBmsy

Froese et al. 2014

State of the Resource

State of the Resource: Stock Size

• The offical reference points for safe biological limits (Bpa) are often based on the lowest stock size ever observed (Bloss)

• With Bpa properly estimated, 52% of the stocks were outside of safe biological limits, and 12% were severely depleted. (Froese et al. 2014)

State of the Resource: Stock Size

• CFP requires rebuilding of stocks above Bmsy

• There are no official reference points for Bmsy

• But 2*Bpa can be used as a proxy for Bmsy • In 2013, 88% of the stocks were below the

proxy for Bmsy Froese et al. 2014)

State of the Resources: Fishing Mortality F

• Fisheries science holds that sustainable fishing mortality Fmsy has to be less than natural mortality M

• However, official estimates of Fmsy exceeded natural mortality M in 76% of the stocks

• Fishing mortality in 2013 exceeded natural mortality in 73% of the stocks, including those that were severely depleted (Froese et al. 2014)

State of the Resource: Maturity

• Fisheries science and common sense hold that fish shall reproduce before being caught

• In 74% of the stocks, the age at first capture was below the age at first maturity (Froese et al.

2014)

State of the Ecosystems

• What is the minimum stock size that still allows species to fulfil their ecosystem role as prey or predators?

• Fisheries science holds that 2/3 of unexploited population size may be a lower limit for regular fish (with F ~ 0.8 Fmsy) and ¾ may be a lower limit for forage fish (with F ~ 0.5 Fmsy)

(Froese et al. in prep)

FisherySeals

Harbour Porpoise

Adult Cod Juvenile Cod

Other Demersal Fish Sprat

Adult HerringJuvenile Herring

Other Pelagic Fish

Flatfish

(Sea-) Birds

Benthic Meiofauna

Zooplankton

Bacteria/Microorganisms

Benthic Producers

Benthic Macrofauna

Detritus / DOM

Phytoplankton

4

5

Tro

ph

ic L

evel

3

2

Pelagic Macrofauna

Food Web of the Western Baltic Sea Sprat is a central food organisms and „natural“ predators must compete for it with the fishery.

Opitz & Garilao unpublished

State of the Ecosystems

• What is the age and size structure that allows a population to reproduce and fulfil its ecosystem role as prey or predator?

• The natural length at first maturity is about 1/3 to ½ of maximum length

• The natural average length of parents is about 2/3 of maximum length

• Starting fishing at about ½ of maximum length allows all fish to reproduce and leads to natural average length; it also maximizes catch and biomass for a given F (Froese et al. in

prep.)

Long-term Catch as a Function of F/M and Length at First Capture

Froese et al. in prep.

Biomass as a Function of F/M and Length at first Capture

Froese et al. in prep.

Maximizing Profits of Fishers

• Profit of fishers is the difference between the value of the catch and the cost of fishing

• Cost of fishing is a function of the abundance of fish

• Highest profits are obtained at about 1.2 Bmsy

• 1.2 Bmsy is therefore the target biomass level in Australia

Follow the Money…

Froese et al. in prep.

Cost

Cost

Cost

Value of catch

Profit

ProfitProfit

Summary

• In 2013, about ¾ of the stocks were too small, were fished too hard, and were caught before reaching maturity

• For stocks to rebuild above levels that can produce MSY, F has to be smaller than Fmsy

• For minimizing impact of fishing and maximizing profits, F should not exceed 0.8 Fmsy and length at first capture should be about half of maximum length

• For forage fish (herring, sprat, anchovy, …) to fulfil their crucial ecosystem duties, F <= 0.5 Fmsy

Thank You