AgentSmith has a beautiful seagull model for free right here in Renderosity Free Stuff. It's a Poser model, so of course you'll need that app to be able to pose it and create a .pz2 for import to Vue. I'm not aware of any gull models in other formats. Sometimes a single gull, or maybe two, off in the distance in the sky can do a lot to help complete a nautical scene. I agree with the comments, this is already a very pleasing, attractive render. Perhaps some more texturing would increase the realism.