There is no regulation on seafood for organic or not, so, in a sense, there is no organic seafood. Seafood in Wholefoods are not organic, they only say that they are from trusted sources, meaning they follow ethical farming and wildlife catching practices. I also think Wholefoods seafood is way too expensive!
Because unless you feed baby organic all the time, the hormones will accumulate in their body regardless of what they eat in the first year. So if you feed them organic in the first year and then stop after that, the total "harm" would be the same as if they eat non-organic food in the first year.