Ecosystem Collapse in Global Fisheries due to Chronic Over-Fishing

1
Ecosystem Collapse in Global Fisheries due to
Chronic Over-Fishing

• Chris Coner
• Will Harrigan-Anderson
• Mike Jolly
• Jeff Schles

2
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

3
Objectives

• In understanding the global fisheries problem due
  to social irresponsibility in relation to
  sustainable management economic and ecological
  aspects were evaluated.

4
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

5
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

6
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.

7
Relationship between components and determinants
of risk in fishery management (Huppert 1996)
8
An Ecosystem Approach to Management
9
Steps Toward Improvement

• 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!

10
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.
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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 90s, the market value of cod
  dropped
• A direct result of over-harvesting

12
Solutions Contd

• 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

13
Ecological Impacts
-Trophic level interactions can be severely
altered as a result of over-fishing. 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 (lt500 species, blue), and
species-rich (gt500 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
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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.)
15
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

16
Examples

• Kelp Forests
• Pacific
• Removal of sea otter, spiny lobster
• Atlantic
• Removal or Atlantic Cod and other large ground
  fish

17
Examples

• Water Quality
• Chesapeake Bay
• Decline in water quality (i.e. eutrophication)
  correlated to decline in oyster populations
• Act as filters through suspension feeding

18
Economic Impacts of Global Over Fishing

• Southeast Asia
• Ghana
• Iceland

19
Background

• One of worlds largest generators of revenue
• Extremely important for many coastline nations
  worldwide
• Over fishing one of major causes of potential
  industry collapse

20
Southeast AsiaLive 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).
21
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

22
Ghana

• Fisheries account for 380 million dollars of
  economic revenue
• Support 56 million people
• No outside commercial fishing allowed in Ghanas
  waters (only Ghana natives)
• Ghana natives also not allowed to fish
  neighboring countries waters

23
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

24
Iceland

• Fishing accounts for 63 of total exports
• 10 of the nations workforce
• Iceland has defended its valuable Cod fisheries
  from other countries
• This has caused over fishing by its own people

25
Icelands Goals

• 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

26
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

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How it really works now

• However, worlds fishing harvests growing at half
  the rate of fishing fleets
• This has caused 75 of the worlds 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

28
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