Wednesday, 30 May 2012

Fish length A LITTLE up, so what...

Heavily fished oceans [1]
Integrity of marine ecosystems can be measured by average size of fish.

Therefore governments gather data on that feature all over the world knowing that a large portion of marine biomass is extracted by fishing. In may parts of the world ocean that share exceeds 30%. Many fish get caught before being mature. Thus the reproduction of fish populations gets brutally truncated!

One of the main indicator for the northern North Sea is average size of fish. It is based on the largest data set available and refers to an area heavily fished that still is trying to recover from lasting heavy over-exploitation. 

The "UK Biodiversity Indicators in Your Pocket 2011" [*] reports for large fish, thus equal to or larger than 40 cm: In in the northern North Sea the proportion of ) dropped 1982 to 2009 from about 15-20% in early 1980-ties to about 5% in 1995,  and since.  

 Large fluctuations in numbers between years are features of the size of North Sea fish populations, but changes in the size structure of fish populations and communities reflect changes in the health of the fish community. Thus not quite healthy change if the proportion of large fish in the Northern North Sea fell from around 15 per cent by weight of the fish community in 1982 to a low of two per cent in 2001 and was around seven per cent in 2009.  

What to do? Don't eat small fish!  Know the size, and say no to buy small  fish.

Haddock in the North Sea should have an average length of more than 30 cm length to have a population of mainly mature fish, ready to repoduce.

Now, in 2009 only some large Haddock are at that size - one out of ten. Sorry your food is gone!



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