As with anything "law", you are responsible for knowing it. Somehow I landed on this web page and was intrigued that it was illegal to fish between Lawrence and Haverhill:
http://www.mass.gov/eea/agencies/dfg/dfw/laws-regulations/cmr/321-cmr-400-fishing.html
"(4) Prohibitions: Except as otherwise provided for in M.G.L. c. 131 and 321 CMR, it shall be unlawful:
(a) to fish in the Merrimack River in the area downstream from the Essex Dam to the Boston and Maine Railroad Bridge"
This is interesting because Methuen is building/renovating a new ramp off Rt. 110. Maybe there's a law that supersedes this (the "otherwise provided"), but I couldn't find it.
Now the more intriguing part for me is how the heck do people fish this area anyways? It is loaded with underwater structures (i.e. rocks) that would be catastrophic for any boat if hit. Are there any old-timers here that have made the trek? To me this is virgin fishing territory, screaming with Pike and Smallies. I'd probably pay someone to navigate me through to the prime real estate. Until then, I don't think I'd make this trip into an exploration adventure.[/quote]