In the research game, a chase can be quickly rewarded. Always nice. Then again, important information sometimes appears unexpectedly, from the clear blue sky. Even better.

Well, chalk up a recent discovery we’ll soon explore – pertaining to 18th-century migratory fish of the Merrimack River – as the latter.

What led to my new finding was enduring personal genealogical interest in “the Fort at Number 4,” once the Connecticut Valley’s northernmost 18th-century military outpost, built in 1743, in what is now the town of Charlestown, New Hampshire, established in 1753.

Nestled between Claremont and Walpole on the east bank of the Connecticut River across from Springfield, Vermont, early Charlestown helped sprinkle our slice of the valley with sturdy northwestern Middlesex County Massachusetts stock named Parker, Shattuck, Williard, Sartwell and Longley, to name some, all from the Groton area. Members of these Yankee military families occupied perilous outposts between forts Dummer and No. 4, and, during the most dangerous times there between 1740 and 1760, temporarily fled to safer places like Northfield, Deerfield, Sunderland, and Hatfield – the north part of which became Whately.

When the dust from the final French and Indian War settled in 1763, many of members of these hardy families settled here, particularly accumulating in Hawley after the Revolution and Shays Rebellion of 1786. Thus, the Fort at Number 4 gene pool is important to genealogists of all stripes researching these local families.

The problem is that, even in this day of Ancestry.com and other comprehensive online sources, the attempt to track them has become a vexing genealogical conundrum. I call it the black hole of Charlestown, New Hampshire – one left by a devastating downtown fire that destroyed the town’s vital records in 1842.

These days, the Charlestown vital records begin in 1842, nearly eliminating any hope of recovering birth, death, and marriage records from the town’s first 100 years. Oh sure, diaries and Bibles with hand-entered family-register forms do occasionally come to light at estate sales or on-site auctions. But time is sadly running out on such important discoveries that provide answers. Thus, the rest of the “answers” are conjectural.

I was nudged into this familiar Charlestown abyss by a Sanderson Genealogy Facebook post from a distant Connecticut relative I have not met. Identifying as a James and Sarah (Parker) Sanderson descendant of 18th-century Conway, I responded with a simple question: Did she know Sarah Parker’s lineage?

“No, do you?” was her rapid-fire answer.

So, the chase was on.

Not unexpectedly, my search led straight to Groton and Charlestown, eventually suggesting the strong but unprovable possibility of parentage by Isaac Parker, Jr. (1709-1760) and his second wife Mehitable. I had been down this road before with James’ three-years-older brother Joseph, who was born in 1741 and married the elusive Lois Fuller – undoubtedly, without hard evidence, the daughter of mysterious Micah Fuller, Fort Number 4’s first blacksmith.

By chance, the hunt for Sarah Parker’s lineage led me to a source that had somehow previously escaped me. I found it in a Fort Number 4 pamphlet footnote: Charles E. Clark’s The Eastern Frontier: Settlement of Northern New England 1610-1763, published in 1970, the year before I graduated high school. I found a reasonably priced copy in “very good” condition, bought it, read it, and gained new insight regarding migratory Merrimack River fishes of the colonial period.

Although as an annual tracker of Connecticut River anadromous fish runs for nearly a half-century I have always viewed Merrimack River fish migration as peripheral data, I have never ignored it. Quite the contrary, I remain alert for accurate assessments of the American shad and Atlantic salmon runs that greeted the first waves of colonial New England settlement.

Clark, a history professor who began as a newspaper reporter in West Lebanon, New Hampshire, and Providence, Rhode Island, visited the subject of Merrimack Valley migratory fish four times in his work chronicling the settlement of colonial Maine and New Hampshire. Not surprisingly, his descriptions of fishing practices and harvests on the Merrimack River closely resemble contemporaneous accounts from the Connecticut River at present-day Turners Falls and Gill. All the data were gathered from second-hand reports gleaned from town histories. In Clark’s case, he relied upon the 1851 History of Bedford, N.H.

And, yes, there were salmon, albeit in far fewer numbers than shad, smaller herrings, and lampreys. Curiously, Clark doesn’t mention sturgeon – Atlantic or shortnose – which appear to have been less important to colonists than to Native Americans.

Clark reports early opposition, by Indians and colonials alike, to migratory-fish-obstructing millsite dams. River-obstruction grievances were addressed by colony regulations mandating New England’s first fish passageways past grist and sawmill dams. Examples are many on the rivers of coastal Maine and New Hampshire, and on the Merrimack River, which flows from New Hampshire’s Lakes Region (Winnipesauke) to Massachusetts’ North Shore.

The late 18th-century fishing practices and harvests described by Clark at Amoskeag Falls in Manchester, New Hampshire mirror those reported by Franklin County historians Epaphras Hoyt (Antiquarian Researches, 1824), Francis M. Thompson (History of Greenfield, 1904), and Edward P. Pressey (History of Montague, 1910). Unfortunately, such second-hand numbers published in town histories are not always reliable, but they’re all we have.

These sources describing two major New England river systems say that shad were harvested in great numbers by seines stretched across heavily-used migration channels, while fishermen employing long-handled dip-nets scooped up many shad and smaller herrings, such as bluebacks and alewives.

Clark doesn’t quantify the daily take of scoop-netters, but he does report individual 1762 seine harvests of 2,500 and 1,500 shad, which is remarkably similar to reports by the Franklin County historians focused on the same activity some 30 years later.

Pressey reports that seine-netters at present-day Turners Falls took “as many as 2,000 shad in one haul, often [with] a giant salmon or two floundering in their midst.” He also says that solitary scoop-netters took as many as 5,000 fish in a day at Turners Falls, without naming the fish.

It would, however, appear that Pressey is parroting Hoyt’s “upwards of 5,000 shad a day by dipping nets at Burnham’s Rock” – a well-known mass of bedrock jutting from the head of the falls on the Gill side to create an ideal fishing site.

As for Merrimack valley salmon, they were obviously there, according to Clark, and his source is airtight: The Diary of Matthew Patten, 1754-1788. An original Scots-Irish settler of Bedford, New Hampshire, Patten (1718-1795) was a man about town and neighboring villages. He records fishing at his Patterson friends’ brook on July 17, 1762 and catching four salmon weighing 66 pounds, an average of 16.5 pounds per fish; two days later he caught 11 more totaling 134 pounds, better than 12 pounds each.

So, yes, salmon existed in the Merrimack valley back then, and take it to the bank that they were here, too – though in far fewer numbers than the accompanying shad, and their smaller herring kin.

The proof’s in the puddin’.