The Common Fisheries Policy
State of Resources and Ecosystems
Rainer Froese, GEOMAR, Germany
10 December 2014
Sustainable Fisheries Internal Seminar
S&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
1200
proxy
Bpa
SSBlim
Bmsy
constant recruitment
1000
Recruits
800
600
Outside safe
biological limits
400
200
0
0
100
200
300
400
500
600
Spawning stock size
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)
Food Web of the Western Baltic Sea
5
Sprat is a central food organisms and „natural“ predators must compete for it with the fishery.
Harbour Porpoise
Fishery
Seals
4
Adult Cod
(Sea-) Birds
Juvenile Cod
Adult Herring
Other Demersal Fish
3
Juvenile Herring
Other Pelagic Fish
Sprat
Pelagic Macrofauna
Flatfish
Zooplankton
2
Trophic Level
Benthic Meiofauna
Bacteria/Microorganisms
Benthic Macrofauna
Benthic Producers
Phytoplankton
Detritus / DOM
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…
Profit
Value of catch
Profit
Profit
Cost
Cost
Cost
Froese et al. in prep.
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