Why is overfishing a problem

Written by Claudia Xian

Recently, I read an article from the overfishing.org, which named "Overfishing--A global disaster". i found it provides very basic information about overfishing, and also includes the updated data about global overfishing.
I decide to paste it in this blog. Therefore, many of my friends could have some basic ideas about overfishing and how serious it is today.

What is overfishing:
Overfishing can be defined in a number of ways. However, everything comes down to one simple point: Catching too much fish for the system to support leads to an overall degradation to the system. Overfishing is a non-sustainable use of the oceans.

Below are a few definitions in use by organisations and governments.

The practice of commercial and non-commercial fishing which depletes a fishery by catching so many adult fish that not enough remain to breed and replenish the population. Overfishing exceeds the carrying capacity of a fishery.

Catching too many fish; fishing so much that the fish cannot sustain their population. The fish get fewer and fewer, until finally there are none to catch.

Fishing with a sufficiently high intensity to reduce the breeding stock levels to such an extent that they will no longer suppport a sufficient quantity of fish for sport or commercial harvest.

What is causing overfishing
Worldwide, fishing fleets are two to three times as large as needed to take present day catches of fish and other marine species and as what our oceans can sustainably support. On a global scale we have enough fishing capacity to cover at least four Earth like planets.

On top of the overcapacity many fishing methods are unsustainable in their own way. These methods have a large impact on the basic functioning of our marine ecosystems. These unselective fishing practices and gear cause tremendous destruction on non target species. Bycatch / discards and bottom trawling destruction are two examples of this.

Why is overfishing a problem:

In the first chapter we discussed already that globally fishing fleets are at least two to three times as large as needed to take present day catches of fish and other marine species. To explain why overfishing is a problem we first have to get an idea on the scale of the problem. This is best done by looking at some figures published by the UN Food and Agriculture Organization. The FAO scientists publish a two yearly report (SOFIA) on the state of the world's fisheries and aquaculture. The report is generally rather conservative regarding the acknowledging of problems but does show the main issues. In general it can be stated that the SOFIA report is a number of years behind time of the real situation.
52% of fish stocks are fully exploited
20% are moderately exploited
17% are overexploited
7% are depleted
1% is recovering from depletion
The above shows that over 25% of all the world's fish stocks are either overexploited or depleted. Another 52% is fully exploited, these are in imminent danger of overexploitation (maximum sustainable production level) and collapse. Thus a total of almost 80% of the world's fisheries are fully- to over-exploited, depleted, or in a state of collapse. Worldwide about 90% of the stocks of large predatory fish stocks are already gone. In the real world all this comes down to two serious problems.
We are losing species as well as entire ecosystems. As a result the overall ecological unity of our oceans are under stress and at risk of collapse.
We are in risk of losing a valuable food source many depend upon for social, economical or dietary reasons.
The single best example of the ecological and economical dangers of overfishing is found in Newfoundland, Canada. In 1992 the once thriving cod fishing industry came to a sudden and full stop when at the start of the fishing season no cod appeared. Overfishing allowed by decades of fisheries mismanagement was the main cause for this disaster that resulted in almost 40.000 people losing their livelihood and an ecosystem in complete state of decay. Now, fifteen years after the collapse, many fishermen are still waiting for the cod to return and communities still haven't recovered from the sudden removal of the regions single most important economical driver. The only people thriving in this region are the ones fishing for crab, a species once considered a nuisance by the Newfoundland fishermen.

What can I do to help:
The effects of overfishing are still reversible, that is, if we act now and act strongly.
When fish stocks decline and and fisheries become commercially unviable the damaged stock gets some rest and generally struggles along on a pathetic level compared to it's pre-fishing level, but doesn't go biologically extinct . A damaged system is struggling and shifting, but can still be active (e.g. filled with jellyfish instead of cod).

If we want to we can reverse most of the destruction. In some situations it might only take a decade, in other situations it might take many centuries. Yet in the end we can have productive and healthy oceans again as is shown in many examples around the world. We do however need to act on it now, before we cross the point of no return.

Every long-term successful and sustainable fishery, near-shore or high-seas, needs to be managed according to some basic ground rules:
Save catch limitsA constantly reassessed, scientifically determined, limit on the total number of fish caught and landed by a fishery. Politics and short time economical incentives should have no role in this.

Controls on bycatchThe use of techniques or management rules to prevent the unintentional killing and disposal of fish, crustaceans and other oceanic life not part of the target catch or landed.

Protection of pristine and important habitatsThe key parts in ecosystems need full protection from destructive fisheries; e.g. the spawning and nursing grounds of fish, delicate sea floor, unique unexplored habitats, and corals.

Monitoring and EnforcementA monitoring system to make sure fishermen do not land more than they are allowed to, do not fish in closed areas and cheat as less as possible. Strong monetary enforcement is needed to make it uneconomic to cheat.

We need to make sure management systems based on these rules are implemented everywhere.
In combination with the banning of the lavish -hidden- subsidies to commercially unviable fisheries.

So, what can I do to help

It's fair to say that individuals cannot solve this global problem all by ourselves, we need politicians to strengthen international law. What we can do is make a difference. Over a decade ago many people started buying dolphin-friendly tuna. Now the time has come to buy ocean friendly tuna. Here are some of the actions you yourself can undertake.
Be informedRead up a bit on the issues of overfishing, have a look at some articles on this site, see if you can find some information regarding your local situation. Keep in mind that while this is a global problem every local situation is different.

Know what you eatIf you eat fish make sure you know what you eat, and pick the ones with the lowest impact. Have a look at the Guide to Good Fish Guides for some tips.
Spread the wordI know, it's all rather obvious, but this is simply how it works. Let your voice be heard!

Friends - Mention to your friends why you refrain from eating certain fish, tell them about the problems we're faceing -pointing them to the Overfishing Basics at overfishing.org might be a good idea.

Elected officials - Write to your elected officials or political party and tell them you are concerned about overfishing and destructive fishing methods. Ask them what they think of the fisheries problem and what they are doing to manage our oceans in a sustainable manner.
Media - Your local newspaper almost certainly has a section dedicated for letters by readers or articles. If you are motivated it writing a letter to the editor is a good way of getting a wide audience.

If you prefer to visit the website, please go to:
http://overfishing.org/pages/what_is_overfishing.php