“Where, in many straggling group,
Gnarled and crooked willows
By a chaffing streamlet stoop,
And their yellow branches droop,
Tow’rd its tiny billows;
Near the banks are little whirls,–
Whirles of fretted water,–
And beneath those rings of pearls
Trout delicious caught are.” 
New Hampshire was probably renown for its fishing even before its shores were first spied by Captain Martin Pring.
“And as the land is full of Gods good blessings, so is the Sea replenished with great abundance of excellent fish, as Cods sufficient to lade many ships, which we found upon the coast in the month of June, Seales to make Oile withall, Mullets, Turbuts, Mackerels, Herrings, Crabs, Lobsters, Creuises and Muscles with ragged Peales in them.”— The Voyage of Martin Pring, 1603
Using spear, net and hook, the fishing industry has supplied a livelihood to countless inhabitants, including the Penacook native people’s who lived within the current boundaries of New Hampshire long before Europeans arrived. Those Europeans had been buying fish from the waters off Newfoundland since 1502. [according to J. Dennis Robinson and credited to Historian David B. Quinn]
In fact, the premium fishing in the waters off the New Hampshire coast was the reason for the establishment of the earliest and first permanent settlements of Pannaway, Dover and Portsmouth. Very early on New Hampshire lawmakers understood the importance of unimpeded water to fish migration. In May 1739, John McMurphy was granted a privilege to build a grist-mill at “Massabesic River,” below the great fall, “provided said McMurphy shall not stop or impede the course of the fish up the said river, but shall and will leave, continue and make sufficient passage for that purpose.” 
In 1865, in response to dwindling supplies of native fish and animals, New Hampshire established a fish and game department, the first one of its kind in New England.Since that date, its efforts have been devoted to the propagation and conservation of fish and game within the state.
The reasons for dwindling fish is as varied as the species itself. The building of dams to capture energy for various mills and manufacturing companies, the felling of trees, the encroachment of homes and farms to once remote lakes and streams, the dumping of waste chemicals and bacteria–the advancement of civilization had a negative impact on wildlife.
It became a tug of war between New Hampshire and Massachusetts to fix the problem. At a meeting in November of 1865, Theodore Lyman III of Massachusetts reported to governor John Andrew that Governor Frederick Smyth during a meeting with him “undertook the high horse and said they would shut down the water from Lake Winnepiseogee [sic] if we did not give the fishways.” 
According to a report of the Commissioners on Fisheries of the State of NH in 1876, “Since the building of The Great Stone Dam at Lawrence in 1847, probably few, if any, salmon have ascended the Merrimack. Fishways were made over several of the obstructing dams in 1866, 1867 and 1868, but they were faulty, and did not amount to much.” By 1876 it was reported that fish-ways had been built and rebuilt when they did not work well at Lawrence MA, and also built at Amoskeag in Manchester NH. Those and other fish obstructions in Lowell and Holyoke added to the decline. Despite efforts, apparently by 1850 the anadromous fish population in the Merrimack River collapsed. [Note: the current fish ladder at Amoskeag Falls in Manchester NH was built in 1989]. 
A similar occurrence befell the Connecticut River. Several major dams at Turners Falls, Massachusetts in 1798 and four others were not equipped with fish ladders. As early as 1814 the salmon and shad had disappeared from this river. They were almost extinct in New England.
Fish hatcheries became necessary to restock these depleted waters. The first fish hatchery built by the U.S. Fish Commission was on Clackamas River in Oregon in 1877. It was operated by Livingston Stone, a former resident (but not a native) of New Hampshire.
Locally, between 1867-1877 several Nashua area businessmen became involved with the fish hatchery movement. They included Oliver Henry Phillips and Dr. Edward Spalding (1867); Gen. George Stark (1870); Hon. Virgil C. Gilman and Charles H. Nutt (1877).  Their work resulted in the Fish Hatchery on Broad Street across from the Nashua Mall. It was “dedicated to the wise use of our fish and wildlife resources.” The hatchery is now owned and controlled by the federal government (is has since 1898) and is part of the Federal Atlantic Reclamation Project.
Today, Nashua National Fish Hatchery is fully immersed in Atlantic salmon and American shad conservation for fisheries in the Merrimack River and other New England waters. The hatchery is also a refuge for the threatened brook floater mussel.
FYI: New Hampshire’s official saltware game fish is the striped bass. Our State freshwater game fish is the brook trout (adopted 1994).
=====S O U R C E S======
 “Farrar’s illustrated guide book to the Androscoggin lakes:and the head-waters of the Connecticut, Magalloway, and Androscoggin rivers, by Charles Alden John Farrar; Lee and Shepard, 1885
 [“Collections, Volume 2, by Manchester Historical Association, J.B. Clarke Company, 1902, page 107]
 [Reasonable Use: The People, the Environment, and the State, New England, 1790-1930″ by John T. Cumbler, 2001]
 Great American Bridges and Dams, by Donald C. Jackson, 1988
 [From Bulletin of the United States Fish Company]