Transcript Ecosystem Collapse in Global Fisheries due to Chronic Over-Fishing Chris Coner Will Harrigan-Anderson Mike Jolly Jeff Schles.

Ecosystem Collapse in Global
Fisheries due to Chronic
Over-Fishing
Chris Coner
Will Harrigan-Anderson
Mike Jolly
Jeff Schles
Overview
• Objectives
– Three essential concepts
• Preferences, Lack of control, and Lack of Information
• Ecosystem Approach to Management
– Steps towards improvement
– Open access fishing
– Solutions
• Ecological Impacts
– Decrease in trophic levels
– Impacts of exploitation
– Examples
• Economic Impacts
– Background
– Impacts
– Case studies: Southeast Asia, Ghana, Iceland
Objectives
• In understanding the global fisheries
problem due to social irresponsibility in
relation to sustainable management;
economic and ecological aspects were
evaluated.
Three essential concepts
• “Preferences”
– An example of this concept is the discussion
of people preferring the ocean with whales in
it even if the presence of whales has no
influence on the production of anything else of
value
– a situation that gives rise to the economist's
notion of existence (or passive use) value
Three essential concepts
(continued)
• “Lack of control”
– Pertains to some event, like the roll of a dice,
where influence by people is insignificant.
– For example the control of weather, the ocean
currents, the climate, or the processes of
recruitment to fish stocks; cannot be
influenced by managers or anyone for that
matter
Three essential concepts
(continued)
• “Lack of information”
– A risk that is independent of the ability to
control the underlying process.
– An example of this is a storm causing
substantial loss of life at sea without warning.
With appropriate weather information, and the
knowledge that a storm is coming, vessels will
stay in port and losses will be minimized.
Relationship between components and determinants of risk in fishery management (Huppert 1996)
An Ecosystem Approach to Management
Steps Toward Improvement
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Ecosystem analysis of marine fisheries
Spatial analysis of fish habitats
These analyses must be prior to fishing!
Implementations of “no-take” zones
“No-take” zones must be physical and
temporal
• Eliminate “open-access” fishing!
Open-Access Fishing
Open access is the condition where access to the
fishery (for the purpose of harvesting fish) is
unrestricted; i.e., the right to catch fish is free and
open to all.
A Solution for Everybody?
• “Open-access” fishing is lucrative
• Over-harvesting leaves fishermen with a
lot of product
• Lots of product means less demand
• In the early 90’s, the market value of cod
dropped
• A direct result of over-harvesting
Solutions Cont’d
• Fishing industry has 53 times the average
industrial mortality rate
• Limiting “open-access” will save lives
• Enforcing quotas will save ecosystems
• Productive ecosystems will save
businesses
Ecological Impacts
-Trophic level interactions can be
severely altered as a result of overfishing.
Figure 2: (a) Trajectories of collapsed fish and invertebrate taxa over
the past 50 years (Diamonds, collapse by year; triangles, cumulative
collapses.) Data are shown for all (black), species-poor (<500
species, blue), and species-rich (>500 species, red). Regression
lines are best-fit power models corrected for temporal
autocorrelation. (b) Map of all 64 LMEs, color-coded according to
their total fish species richness. (c) Proportion of collapsed fish and
invertebrate taxa (d) average productivity of noncollapsed taxa (in
percent of maximum catch)
(Worm et al. 2006).
Worm et al. 2006
Decrease in trophic levels
• Fishing down the
food web
• Decline in trophic
levels
• Transition from
longe-lived
piscivorous fish to
short-lived
planktivorous fish
Trend of mean trophic level landings in global
fisheries (Pauly et al.)
Impacts of exploitation
• Loss or removal of top predator(s) results
in alleviated pressure
– Smaller species expand spatially and
numerically
• Studies have shown that overfishing has
resulted major structural and functional
changes
examples…
Examples
• Kelp Forests
– Pacific
• Removal of sea otter, spiny lobster
– Atlantic
• Removal or Atlantic Cod and other large ground
fish
Examples
• Water Quality
– Chesapeake Bay
• Decline in water quality (i.e. eutrophication)
correlated to decline in oyster populations
• Act as filters through suspension feeding
Economic Impacts of Global
Over Fishing
Southeast Asia
Ghana
Iceland
Background
• One of world’s largest generators of
revenue
• Extremely important for many coastline
nations worldwide
• Over fishing one of major causes of
potential industry collapse
Southeast Asia
Live Reef Fish Trade
• Comprised of Indonesian
Island Countries
• ~1 Billion USD Annual
Revenue
• Supplies Hong Kong,
Mainland China, Taiwan
• Main Species: Large
Groupers, Humphead
Wrasse
(Cesar et al 2000).
Over Fishing Impacts
• Fish harvested as fry or fingerlings
• Grown to maturity in captivity
• Caused a decrease in reproducing adults
in the wild
• Leading to a severe decline in fish
populations
Ghana
• Fisheries account for ~380 million dollars
of economic revenue
• Support 56 million people
• No outside commercial fishing allowed in
Ghana’s waters (only Ghana natives)
• Ghana natives also not allowed to fish
neighboring countries’ waters
Lack of Local Enforcement
• Key species: Sardinellas, Trigger Fish,
Club Mackerel
• Causing ecosystem degradation, as well
as a collapse of the fishing industry
• These species rapidly disappearing
• 56 million people in jeopardy of losing their
jobs
Iceland
• Fishing accounts for 63% of total exports
• 10% of the nation’s workforce
• Iceland has defended its valuable Cod
fisheries from other countries
• This has caused over fishing by its own
people
Iceland’s Goals
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Currently fishing 45% of fishable stock
Goal is to reduce this amount to 25%
Limiting use of fishing grounds
Implementing quotas to limit fish landings
Global Ramifications
• Studies show, annual fishing harvests
could rise 10 million metric tons, $16
billion to gross worldwide revenues
• Key is to allow fish populations time to
recover, reproduce
• $2.9 billion increase in US alone if
sustainable practices reached
How it really works now…
• However, world’s fishing harvests growing
at half the rate of fishing fleets
• This has caused ~75% of the world’s
fisheries to be considered fully exploited
• All nations affected in some way,
economically or socially
• These unsustainable practices are leading
to the potential economic collapse of entire
nations
Literature Cited
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