There are no dolphins on the enterprise-D.
There were dolphins on the Enterprise D. Geordi showed them to the Ferengi in 'The Perfect Mate.' It is unknown what happened to the dolphins after the ship crashed.
There's two likely answers to this question, depending on where said Dolphins were located on the Enterprise-D.
1. If said Dolphins had been housed in the Stardrive section, it's unfortunately likely that they were not evacuated in the minutes the crew had to conduct a full evac of that section into the saucer. As we saw no physical evidence of crew carrying dolphins or beaming dolphins into the saucer section in Generations, the only conclusion we can form is that they were killed in the subsequent explosion of the stardrive shortly after the saucer separated and the warp core breached. We can see a massive explosion behind the saucer section as the stardrive erupts into flame, but a close study of that explosion shows no Dolphins in the debris flotsam. It's difficult to conclude that the Dolphins were in fact in the Stardrive section.
2. If Dolphins had been evac'd to the Saucer, survival would largely depend on where they were located. Generatations makes it clear that the saucer suffered massive internal damage during the crash, with bulkheads failing, windows designed to withstand the vaccum of space shattering, and fires erupting throughout different areas. It's likely that had they been on the lower decks of the saucer which bore the full brunt of the impact with the Veridian III jungles, the chances of the water tank they were enclosed in remaining intact would have been minimal. As we see no evidence of the Dolphins in the closing minutes of Generations as the crew are packing up their belongings in preparation for leaving for the last time, it's difficult to determine if they had survived or not. Close analysis of the scene where a shuttlecraft flies over the wrecked saucer on the surface of Veridian III heads no evidence of Dolphins. —Preceding unsigned comment added by Bracyj (talk • contribs)