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Ecosystem Collapse in Global Fisheries due to Chronic Over-Fishing

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Historical Overfishing and the Recent Collapse of Coastal Ecosystems Science Magazine. 293: 629 637. Kenneth T. Frank, Brian Petrie, ... – PowerPoint PPT presentation

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Title: 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.
11
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
14
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

27
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
Literature Cited
  • Atta-Mills, J., Alder, J., Sumaila, U. The
    Decline of a Regional Fishing Nation The Case
    of Ghana and West Africa. Natural Resources Forum
    28. 2004. 13-21.
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    Apostolaki, P., and Santora, C. 2005. A
    perspective on the use of spatialized indicators
    for ecosystem-based fishery management through
    spatial zoning. Journal of Marine Science.62 469
    476.
  • Botsford, L. W., Castilla, J. C., Peterson, C. H.
    1997. The Management of Fisheries and Marine
    Ecosystems. Science. 277 509 515.
  • Cesar, H., Warren, K., Sadovy, Y., Lau, P.,
    Meijer, S., Ierland, E., Marine Market
    Transformation of the Live Reef Fish Food Trade
    in Southeast Asia. Collected Essays on the
    Economics of Coral Reefs. CRDIU, Kalmar
    University, Sweden. 2000. 137-157.
  • Declining Cod Stocks Threaten Icelands Economy.
    Planet Ark. Stockholm. 3 Dec 2001.
  • Hughes, T.P. 1994. Catastrophes, Phase Shifts,
    and Large-Scale Degradation of a Caribbean Coral
    Reef. Science 2651547.
  • Huppert, D.D. 1996. Risk assessment, economics,
    and precautionary fishery management. FAO
    Fisheries Technical Paper. 350 103 128.
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  • Kenneth T. Frank, Brian Petrie, Jae S.
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  • Newell, R. I. E. 1988. Understanding the Estuary
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  • Pauly, D., Christensen, V., Dalsgaard, J.,
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  • Rosser Jr., J.B. 2002. Implications for fisheries
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  • Somma, A. 2003. The Environmental Consequences
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