Fighting for an eel

I took my long lens for a walk, hoping find the kingfisher I saw a few days ago. No sign of it, but as I was walking over Perth bridge there was a commotion in the water below. Two goosanders were fighting over something, and a gull swooped in to try its luck.

From the photos I can see that one of the goosanders had most of an eel, minus head; too big to swallow easily. It dropped it (1st extra), and both birds dived. After a few seconds they came up and one managed to swallow the eel (2nd extra). Whether it was the first bird or the attacker I have no idea.

I'm a novice at bird photography, and I found some advice on how to set up my camera for best results. I was pleased with the result today, except that at f/4 I didn't have enough depth of field to keep all the action fully in focus.