Surf fishing is very popular on Nantucket, especially in the late spring when bluefish are running (the best place to go after them is Great Point). Freshwater fishing is also an option at many area ponds.
Many of the fishing charters will gladly make detours to spot whales.
Captain Peter Kaizer, a former commercial fisherman, guarantees a good catch aboard the Althea K (508/228-3471); he also offers whale-watching and charter cruises.
Captain Tom's Charters (Public Landing, Madaket. 508/228-4225. www.captaintomscharters.com) win consistent "best of" awards for Tom Mleczko's hands-on expertise. Choose among rips, bars, surf, open water, and flats (the latter for the added challenge of sight fishing with fly rods).
A permit is required for shellfishing, specifically foraging for littleneck and cherrystone clams, quahogs, scallops, oysters, steamers, and mussels. You can pick one up -- along with tips on where and how to get the best catch -- at the Marine and Coastal Resources Department (34 Washington St. 508/228-7261).