PINS "hotline" for weather and beach conditions, tide, etc. is: 361-949-8175. It is an automated recording updated each morning.
A good place to find fishing reports for the region is:
Corpus Fishing.com
The various fishing spots are listed in a column on the lefthand side of the page.
I'd encourage you to make sure you are well equipped to travel down PINS. The park website has a good writeup on traveling down island, or look at the "desperate for beach camping" thread here on Wild Texas.
Have a great trip!