Overfishing the Oceans

The Facts

 Gray Redding

 Facts about Over Fishing of the world's fisheries

  • Overfishing
  • Dependence on fish for much of world
  • Increased draw on the fish populations
  • Negatives of Commercial fishing 

Over Fishing - To fish (a body of water) to such a degree as to upset the ecological balance or cause depletion of living creatures.


To fish a body of water so extensively as to exhaust the supply of fish or shellfish. (Answers.com, Overfishing)

Fish and Shell Fish have the largest share of the available food for meat products with a 33% holding (Mackenzie, Our Changing Planet)

Fish is an important part of the daily diets in many nations, providing roughly 40 per cent of the protein consumed by nearly two-thirds of the world's population

With so many fishing vessels in the world, massive fleets are migrating away from over fished areas and are stalking the planet on a desperate search for less exploited fishing grounds.

The world's marine catch has increased more than four times in the past 40 years -- from 18.5 million tons in 1950 to 82.5 million tons by 1992

    The above picture is a chart of a sustainable take from fishery.  The fleet production must be in tune with the biomass production in order to keep the chart in the green, sustainable section. (source - http://en.wikipedia.org/wiki/Overfishing)

Seven out of ten (69%) of the oceans' commercially targeted marine fish stocks are fished beyond ecologically safe limits, being either fully or heavily exploited, overexploited, depleted, or very slowly recovering from collapse after previous overfishing.

One-quarter of the planet's biological diversity is in danger of extinction within the next 30 years. In the ocean environment, commercial fishing stands as one of the greatest biodiversity threats.

Overfishing damages much more then fish populations. Extracting too many fish from an ecosystem can reduce the survival chances of other predators in the marine food web, including populations of marine mammals, seabirds, turtles, sharks and a host of other species

The depletion of food supplies is not the only threat to marine wildlife posed by fishing operations. Many millions of animals other than fish are severely injured or killed each year through deadly interactions with fishing gear

One-quarter (25%) of all the fish pulled from the sea never make it to market. They are left or thrown away as by catch.

Since 1970, the world's fishing fleet has expanded twice as fast as world catches

Worldwide, about 13 million people make all or a major part of their living from fishing. More than 10 million of them work in coastal waters on little boats powered by paddles, sails or sometimes outboard motors, with only a few crew members.

Biomass Over fishing - occurs when fishing mortality has reached a level where the stock biomass has negative marginal growth (slowing down biomass growth), as indicated by the red area in the figure.  Fish are being taken out of the water so quickly that the replenishment of stock by breeding slows down. If the replenishment continues to slow down for long enough, replenishment will go into reverse and the population will decrease.

Economic Over fishing - Fish are being taken out of the water so quickly that the growth in the profitability of fishing slows down. If this continues for long enough, profitability will decrease.

The cod fishery in New England, for example, caused annual landings to decrease 88% between 1990 and 2000.  This is a numerical description of the situation described in Technical Issues.

54 billion pounds of by catch are discarded annually 

In 1948, the largest trawlers weighed some 1,216 tons. Today, the American Monarch (above), one of a fleet of super-trawlers, is 6,730 tons and as long as a football field.


The above facts were provided by 




Book - Mackenzie, Fred.   Our Changing Planet 



Technical Issues

Leadership Issues

Ethical Issues