The seas, fish and what we are doing to them

The seas are a tremendous resource for humanity. They contain fish and sea food, which have important nutrients for humans and the seas also act as a reservoir for carbon dioxide, where trillions of tonnes of it are stored.  Ninety percent of sea life lives in the first two hundred metres of so of the sea, which is called the sunlight or Euphotic zone. The next layer, about 750 metres deep is the twilight or Disphotic zone. This is colder and supports less sea life, which has to be adapted to cope with the high pressure and very low light levels.  The midnight or Aphhotic zone comes last; here there are no plants and sea animals that do not need eyes to sea and which can eat bacteria growing on materials down there.

Around coastlines are dead zones; these are caused by fertiliser and nutrient run off, sewage, animal waste and even human made air borne pollution. These remove oxygen from the water or change its chemical balance so instead of a thriving fish pollution the dead zones are only fit for algal blooms. The number of dead zones and their size has rapidly increased in the past forty years. You can find them in Chesapeake Bay in the United States, the Baltic, Black and northern Adriatic seas and the Scandinavian fjords. New dead zones are appearing off South America, China, Japan, south east Australia and New Zealand. The most famous dead zone is in the Gulf of Mexico, created by a huge volume of nutrients and fertilizers carried down by the massive Mississippi River.

The animals that live in the sea are under threat from these dead zones and also from over fishing. The species of fish that appear in fish and chip shops is dwindling and the fish is becoming very expensive. Some species have vanished from the shores around these islands and some new species are becoming more prevalent. Taken as a whole fish are becoming scarcer and harder to find.

In Scotland, the soils and waters of the Galloway Hills have become measurably more acidic during the last century. Planting coniferous trees seems to have changed the water chemistry. Trout and salmon are sensitive to this increased acidity. It seems that even a superficially benign event – such as planting trees, can adversely affect fish populations.

In one sense this would not matter too much, if the fish had somewhere else they could go, but the impact of what we do on the oceans as a whole is such that the fish are rapidly running out of usable Euphotic and Disphotic zones in which to live, and when they find a clean area of ocean they are caught for human food..

The United Kingdom’s Government is trying to protect the fish and marine life in the seas around its shores by a new piece of legislation, the Marine Bill. It will create “marine conservation zones”. It is not sure how these zones will work.

There is another way of protecting the marine life is to create “no fishing” zones which can stay as no fishing zones for a number of years, to enable fish stocks to recover, and when those zones have come into use create other no fishing zones.

With the UK’s membership of the common market our fisheries are under EU control, not UK control, so it would need EU co-operation to conserve fish stocks properly.

A small no fishing zone was created five years ago on the eastern side of the isle of Lundy off the coast of Devon.  Monitoring has shown that in five years lobster populations have increased fivefold, whereas lobster populations in similar areas where fishing is allowed have remained at the same levels.

Fishing is a good example of an activity that is directly affected by our impact on the environment where with proper management taking a long term view we can preserve and enhance an important supply of food instead of what we now do, which is to use our impressive technology to sweep the seas clean of as much fish as we can catch.

But there has to be more than creating no fishing zones. We have to be more careful about the fertilisers that we allow into the seas by run-off (another good reason for supporting organic farming) and much more strict about the pollution that we put into the seas, such as oil, waste and sewage. We also have to work hard to make fishing more sustainable so that we control more rigorously some of the techniques that the commercial fisheries use.

There is no doubt that fish farming will eventually increase to the extent that most of the fish on our tables comes from a fish farm, rather than the wild river or sea.

When you buy and eat fish it would be nice if we could be informed as to whether the fish was farmed, where and how it was caught and whether the fishery uses sustainable techniques or simple drag nets what it can find.

Fish and sea food are good for you (almost always) and we need to keep it that way and ensure an abundant supply for everyone.

3 Responses

  1. I agree the fishing should be controlled!. I want the variety of fish to be sustained and so that i get omega 3 brain food from a variety of tasty fish!

  2. As well as the iodine annd other trace elements.

  3. I completely loved coming upon your post.

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