Here's an interesting article about how increases in ocean noise cause whales to stress. While this reports on a study done in the Bay of Fundy, Canada it is applicable to our waters and we need to take heed.
This article states that '...ocean noise has risen substantially in recent decades along with the growth in global shipping;one analysis showed that the north-eastern Pacific is 10-12dB louder now than in the 1960s.'
Remember my blog about how heavy ship traffic is around our shores? (http://whalessrilanka.blogspot.com/2011/10/global-shipping-traffic-in-prime-blue.html.) Now revisit the figure that accompanied the blog and you will notice that ship traffic around our southern coast (and therefore within blue whale habitat) is equal to, if not higher than in the north-eastern Pacific and we have no idea how this affects our acoustically dependent marine life above and beyond the ship strikes that occur!
Click here for the full article: http://www.bbc.co.uk/news/science-environment-16926005