90% of fish gone...

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90% of fish gone...


My goodness next time you open a can of tuna remember that we are eating the last of the fish, with abandon. What we see as normal, may be a luxury for our children's children.

Analysis of data from five ocean basins reveals a dramatic decline in numbers of large predatory fish (tuna, blue marlins, swordfish and others) since the advent of industrialized fishing.

The world's oceans have lost over 90% of large predatory fish, with potentially severe consequences for the ecosystem. These findings provide indirect support for goals established at the UN's World Summit on Sustainable Development in Johannesburg last year.

UN officials argued that three-quarters of the world's fisheries were fished to their sustainable limits or beyond, and made proposals for the restoration of depleted fisheries by 2015. Data on predatory fish are important as they are not dependent on datasets from commercial fisheries, which can be unreliable.

In a letter to Nature (15 May 2003), Ransom A. Myers and Boris Worm report the following:

Analysis suggest an average equilibrium1 of 10% of pre-exploitation levels, with 95% of the individual communities2 landing between 5% and 24%.

An 80% decline in biomass typically occurred within 15 years of industrial exploitation. This is usually before scientific monitoring takes place.

As new areas were exploited, they were initially very rich in fish, but catch rates were greatly reduced in just a few years.
Compensatory increases of fast-growing, non-exploited species were observed, but were in most cases subdued by increased bycatch3 mortality or by becoming targets for trawling.

Presently, all major sources of large predatory fish are exploited and severely diminished.

Basis of study

This data was collected from research trawl surveys from northwest Atlantic Ocean, the Gulf of Thailand and the Atlantic Ocean off South Georgia. The surveys included codfishes, flatfishes, skates and rays, among others. For oceanic systems, Japanese pelagic longlining data from 1952 - 1999 were used. It represents complete catch rate data for tuna, billfishes and swordfish.

Data from most of the northern hemisphere was excluded, since modern fishing methods have been in use for decades before scientific surveying began.

To estimate the reduction in biomass, they used "catch per 100 hooks" for each area, not total yield. They assumed that catch rate is proportional to biomass, but added that this probably underestimates the decline, since intensive fishing tends to reduce average age and weight of the preyed fish.


Reduced yield leads to changed strategies for the fishing industries. If some species are fished into oblivion, other species are tracked down and in the end severely reduced. There is a global trend towards ever lower mean trophic levels of the catch, as reported by the UN Food and Agriculture Organization (FAO). Also, the management goals of today are to stabilize the fish stock at current levels. But is it really beneficial to stabilize the stock at levels that are some 10% of pre-industrial levels?

(For a different write-up and interview with Myers, see CNN and National Post )

1. Equilibrium as in residual equilibrium, which is reached after infinite time. Levels near the residual equilibrium are reached pretty fast though.
2. A community is the population of a species in a local ecosystem, e.g. Southern Grand Banks or Gulf of Thailand.
3. Bycatch is fish that is caught in trawls and other fishing tools, but not intentionally targeted.
By netchicken: posted on 21-5-2003

looks like people are starting to wake up...

Cod stocks only 1/10 of the levels of 1970!
Thats amazing, considering the amount of development and fishing tech since then, they have indeed stripped the seas empty.

more on the site.....


The fishing industry must change if many of the familiar fish round the UK coast are to stand any realistic chance of survival, Prince Charles has said.

He told a charity promoting sustainable fishing that overfishing threatens once- abundant species with extinction.

People should not stop eating fish, but should only eat species which were not in decline, the prince added.

Nine former UK environment secretaries and the present incumbent all say world fish stocks are collapsing already.

'Lessons are obvious'

The prince was speaking at a gala event to raise money for the work of the Marine Stewardship Council (MSC), which says it is the only global charity working exclusively to save global fish populations.

It seeks to do this by awarding its label to fisheries it judges sustainable: seven have been certified so far, and more than 40 others are at some stage of the certification process.

Prince Charles said that with cod stocks in the North Sea now at one tenth of the 1970 level, the "lessons are obvious".
By netchicken: posted on 8-3-2004

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