Fishing in the Newburyport area is still a month away.
Pick up a copy of this week's Fisherman, Captain John Gribb (from Newburyport) has an article about Shad fishing on the Merrimack. In fact, get yourself a subscription to the Fisherman, it's like $50 for two years, that's 50 cents a copy.
Stripers will finally arrive in mid-late May and then the bite will be on all summer long. Live bait like mackerel, pollock or herring are best, I guess clams are pretty good too. I plan on trying a bunch of artificials this year, bucktails, rubber shad, etc. Talk to the gals at Surfland or the guys at Crossroads for details.
There is a very active saltwater fly fishing group on Plum Island, some of them post here and at
http://www.flyfishsaltwaters.com/cgi.../Ultimate.cgi.
I live in Byfield and fish the Merrimack and Parker River, ask around, most people are willing to help.