What you are experiencing is called print-through, and it's very common. What weight fibreglass did you use behind the gelcoat? The heavier the first layer of glass you use, the more noticeable the print through effect will be. Often you will still get print using a 100g or 225g cloth though, so don't be too upset if that's the case. The absolute best way to eliminate it is to allow the mould to cure for longer (or do an elevated temperature cure) prior to demoulding. The effect is caused by shrinkage of the resin, so the better cured it is the less it will shrink. 

It also looks like you've got a fair few voids in the coupling coat behind the gelcoat. These will leave areas of unsupported gelcoat, which will be extremely brittle. You want to take a lot of care to get rid of any and all trapped air in the coupling coat.