Careful what you wish there Brashy, it may come true. There are parts of the country where Dogfish are considered to be vermin. However, I would rather catch a \"Dogfish\" than a \"No-fish\".
The ecology of the seas around Britain have most certainly changed over the last two centuries. The reasons are probably manyfold, including over fishing such that alternative species start to occupy the niche left by others. Is this what is happening with the decline in Cod stocks and the apparent increase in Dogfish? Climate change could also contribute to the species shift. However, we only have some 200 years of reliable weather data on which to base our theories of global warming / cooling, the next ice age etc.
I think the earth is like a smokers lungs, if you stop smoking you will stop the damage and eventually the body will repair that lung. However, there is a point of no return, continue smoking and you will continue the damage and eventually if something else doesn\'t kill you, then lung cancer will. So if we don\'t stop polluting the earth and taking away natural resources faster than they can be replenished, then the earth will die. If we stop and it is not to late, then nature will repair the earth, and our grand children may inherit a planet in a better condition than we have now.
Oh yes, I once caught one of those Dragonets of SS pier.