Ecosystem Collapse in Global Fisheries due to Chronic

Over-Fishing

Chris Coner Will Harrigan-Anderson

Mike JollyJeff 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

• 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 FishingOpen 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

Worm et al. 2006

-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 (<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).

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 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).

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

• 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

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