A gulf menhaden
Pelicans, like many of the birds and larger fish in the Gulf survive off a diet that consists mostly of menhaden. This is a small, oily fish full of tiny bones that fishermen disregard. Because of the bones and the taste and the size, menhaden aren't considered food fit for humans. Most fishermen will catch the menhaden in nets and then use them as chum to attract other fish. These are small fishermen catching small fry. There is another kind of fisherman who catches every single menhaden he can find for sale.
Omega Protein is the corporation that dominates the menhaden fishery. As they boast, and rightly so perhaps, they use every single bit of this small fish. They manufacture those omega-3 fish oil pills you find in health food stores. They also grind up the fish for animal feed and pet food. That chicken you eat was probably fattened, at least partly, on menhaden meal. Mmmmm.
The data isn't yet in on how the menhaden stocks are faring in the current BP Gulf of Mexico oil spill fiasco. This once plentiful fish will no doubt be affected, however, and not for the better. Menhaden stocks are already at historic lows. No matter how many oily pelicans are scrubbed clean with dish detergent, they will still need to eat. The Gulf ecosystem will be in a shambles for years to come, the food chain disrupted.
Someone will devise some other feed for the factory farmed chickens. Omega Protein may already be on the case. That's not the main worry. What about the pelicans? They feed themselves and there won't be many fish for them to find.
If you are taking fish oil supplements, you may want to switch to eating tinned sardines from Morocco. The pelicans will thank you if they survive this.