The Anthropocene on Our Water Environments
When I think about our classes this week and how we discussed the Anthropocene in relation to our environment, an important topic came to mind. Overfishing. Why because it is definitely a way in which mankind is drastically changing the environment that we live in.
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.
So 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? Above I already discussed 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 key issue and trends. Due to the difficulty of aggregating and combining the data it can be stated that the SOFIA report is a number of years behind 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.
Now as bad as this situation seems, there is still hope. By taking safety precautions like safety catch limits, policy enforcements, and protecting important habitats, we can reverse the damage that has been done so far to many overfishing problems. It may take decades or even centuries but we can still do something as long as we put in the effort.
http://www.lehigh.edu/~kaf3/books/reporting/glossary.html
http://www.reefed.edu.au/home/glossary/o
http://www.fishonline.org/information/glossary/
The FAO Fish and Aquaculture organisation - http://www.fao.org/fi/default.asp
The State of World Fisheries and Aquaculture (SOFIA) can be found on http://www.fao.org/sof/sofia/index_en.htm. Figures on this page are taken from the 2006 version of the report. As of 2011 the situation has became worse.