Transcript SAES CH14x

Do Now
- What is the future of fishing and
why is this the case?
- Why is this especially important for
New England?
- What is currently being done about
this? What are pro’s and con’s of this
approach?
CHAPTER 14 FISHERIES AND AQUACU
FISH IN A
WAREHOUSE?
How one Baltimore fish scientist could change the way we eat
WHAT IS A FISHERY?
The industry devoted to commercial fishing, or the places
where fish are caught, harvested, processed, and sold.
WHY ARE FISHERIES SO
IMPORTANT?
Because humans rely on fish protein.
over 15% of the
world
population rely
on fish as their
main source of
protein
poorer nations – fish is
cheaper than other meat
wealthier nations – fish is
part of a health-conscious
diet due to the omega-3 fatty
acids found in cold saltwater
species
This reliance
on fish
spawns a
huge global
fishing
industry – 200
million people
and a revenue
of $130 billion
But the oceans pay a price for the
health and economic benefits that fish
provide humans.
WHAT IS A COLLAPSED
FISHERY?
A collapsed fishery is when in a
commercial fishery the annual catches
fall below 10% of their historic high.
WHAT CAUSES A FISHERY
TO COLLAPSE?
A collapsed fishery reflects a
combination of factors:
• technological advances
• increasing demand for fish
• tragedy of the commons
• discounting future value
Technological advances feed
the increasing demand for fish
steam
engines, flash
freezing, and
trawler ships
that could
drag huge
nets behind
them
enables fishers to
travel further into the
ocean, catch more fish,
and transport them
greater distances than
ever before to meet
market demand
this leads
to
declines
in fish
stock
Additional consequences of technology:
Pollution – from increased fishing traffic
Bycatch – the capture of non-target species often exceeds
the target species catch
Damage to the sea bed – trawling damages
ecosystems and spawning grounds
Tragedy of the commons
discounts the future value of fish
As nobody owns
the ocean, the
choice is simple
for an individual
fisher: “If I don’t
take it, someone
else will.”
It doesn’t make sense to
leave any fish behind,
when the immediate
value of taking the fish is
greater than the
immediate cost—even if
it means fewer fish to
harvest in the future
This leads to
overuse and
harm to fish
stock
without
regard for
the future
COMMERCIAL FISH CATCH IN NEWFOUNDLAND-LABRADOR
SHELF
This could mean that we may not be able to harvest fish this way
for much longer.
WHAT IS THE CURRENT STATUS OF
MARINE FISHERIES?
WHAT IS MAXIMUM
SUSTAINABLE YIELD (MSY)?
The amount of fish that can be
harvested without decreasing the
yield in future years.
Currently, 68% of the global marine
fisheries are sustainably fished.
If so, then what is the problem?
The other 32% of global marine
fisheries are overexploited, and this
number has increased threefold since
the 1970s.
WHAT IS AN
OVEREXPLOITED FISHERY?
A fishery in which more fish are
harvested than is sustainable in the
long run, leading to population decline
and possibly a depleted fishery.
WHAT IS A DEPLETED
FISHERY?
A depleted fishery is when the fish population is
well below historic levels and the population’s
reproductive capacity is low, meaning that
recovery will occur slowly, if at all.
WHAT ARE THE CONSEQUENCES
OF DEPLETED FISHERIES?
With the loss of higher trophic level species like
cod, fishers pursue the herring, crabs, and shrimp
at lower trophic levels – called “fishing down the
food chain.”
Declining fish populations impact
ecosystems – especially those with
simple food webs.
When
codinare
Declines
cod
depleted,
fishers
and their prey
move
down
the
increase
hydroid
food chain and
populations
pursue
prey,
making cod
it hard
for
thereby
reducing
cod to recover
as
food
supply
the
they eat
the for
same
cod, and
food as young cod,
jeopardizing
and also feeditson
recovery.
the juvenile cod.
WHAT ARE SOME POTENTIAL
SOLUTIONS TO PROTECT FISHERIES?
Exclusive economic zones
zones that extend 200 nautical miles from the
coastline of any given nation, where that nation has
exclusive rights over marine resources, including fish
Marine protected areas
discrete regions of ocean that are legally protected
from various forms of human exploitation
Marine reserves
restricted areas where all fishing is prohibited and
absolutely no human disturbance is allowed.
Sustainable fishery
fishing that ensures fish stocks are maintained at healthy
levels, the ecosystem is fully functional, and fishing activity
does not threaten biological diversity
However, many scientists say that the
real solution to our fish problem won’t
be found in the ocean at all.
WHAT IS AQUACULTURE?
Aquaculture, or fish-farming, is the rearing of
aquatic species in tanks, ponds, or ocean net pens.
Aquaculture provides more than half of
all seafood consumed world wide. But,
they come along with many
environmental challenges.
WHAT ARE THE POTENTIAL
PROBLEMS WITH
AQUACULTURE?
Aquaculture: Problems and Solutions
Another solution to the problems of
conventional aquaculture is to move it
indoors.
WHAT IS A RECIRCULATING
AQUACULTURE SYSTEM (RAS)?
A recirculating
aquaculture system
produces fish in
indoor tanks where
the environment is
controlled through
water treatment and
recirculation.
HOW DOES RAS WORK?
REQUIRED PROCESSES IN RAS
Temperature,
salinity, and
pH
Fine and
dissolved
solids
removal
Aeration or
oxygenation
Waste solids
removal
Carbon
dioxide
removal
Disinfection
Fish
culture
tank
Biological
filtration
(nitrification)
HOW DOES RAS MEASURE UP
TO OPEN WATER
AQUACULTURE?
RAS has several OPERATIONAL
advantages over open water systems:
The system
can be sized
as needed.
The system can
raise marine
species
independent of
location of the
aquaculture
operation.
Conditions in the
tanks can be
precisely
controlled to suit
a specific species
of fish.
RAS has several ECOLOGICAL advantages over
open water systems:
As they are indoors,
they reduce habitat
loss
The system is
biosecure—there is no
risk of the fish from RAS
operations escaping into
the wild.
The fish growing in RAS
tanks require less food
per pound, and convert it
into flesh at a much
higher ratio.
Reducing the distance
between the fishery and
the consumer means less
energy spent on
transportation and cold
storage
RAS uses waste to produce energy:
RAS employs
carefully calibrated
microbial
communities to
manage waste in
which the bacteria
convert some 96%
of the solid waste
into fuel-grade
methane
However, marine aquaculture
presents some unique challenges.
For one, most commercially
important marine fish—such as
sea bream, sea bass, and tuna—do
not reproduce in captivity.
Clicker Question
How did Dr. Zohar get his captive fish to
spawn and reproduce?
a. He changed the lighting to mimic
outdoor lighting cycles.
b. He controlled the levels of interactions
among the fish.
c. He carefully controlled the salinity
regimes in the tanks.
d. He injected the fish with hormones.
RAS is better suited to
certain regions of the world.
RAS technology is complex and expensive to set up and
operate.
• not feasible in poorer regions of the world
• not feasible in water-starved areas
As the type of fish grown can be chosen based on
economic opportunity rather than location, such a
system is potentially well-suited for markets in
developed countries, like the US.
“We have to make a distinction
between having an impact and being
sustainable. Anything you do is going
to have an impact on the environment.
The real question is whether it’s an
impact the environment can absorb
and recover from or one that will do
permanent damage”
- Lorenzo Juarez