Jack Hemingway, who has died in New York aged 77, was the eldest son of the novelist Ernest Hemingway and bore a striking resemblence to his father. However, despite having grown up under the shadow of a famous writer, notorious drunk and hunter, Jack carved out a life which reversed some of the values of his distant, disengaged father.
He had long been his family's emissary, attending conferences, sitting on the advisory board of the Hemingway Foundation and, with courtesy and good humour, welcoming visitors to the family home at Ketchum, Idaho, with its breathtaking view across Sun Valley. Visitors admired the rich horde of family memorabilia - Hemingway's typewriter, a trunk which had been with the writer in Paris in the 1920s and a handsome fake Picasso hanging in the bedroom - before adjourning to the Olympic bar, one of Papa's favourite hangouts in Ketchum.
But his greatest love was fly fishing and the outdoor life, and after his father's suicide in 1961, he settled in Ketchum. Growing increasingly interested in the problem of conserving Idaho wildlife and environment, he became a persuasive advocate for enlightened policies in a state famed for its hunting and fishing.
Hemingway served as a commissioner on the Idaho Fish and Game Commission from 1971 to 1977 and was instrumental in the adoption of a "catch and release" law, which did much to preserve trout stocks while those in neighbouring states declined.
He was born in Toronto, an easy birth made even more congenial when his mother, Hadley, his father's first wife, was given laughing gas ("Hadley says the whole childbirth business has been greatly over-rated," Hemingway wrote to Gertrude Stein, who became Jack's godmother). Nicknamed "Bumby", Jack spent his early years in Paris and the Austrian Alps. These years are described in A Moveable Feast, Hemingway's autobiography, published in 1964. The book ends with a description of Hadley greeting him at the train station, smiling, "her lovely face tanned by the snow and the sun", and Bumby at her side, "blond and chunky and with winter cheeks looking like a good Voralberg boy." Hemingway had just decided to abandon his wife and child.
Jack was five when his parents divorced. Sent to boarding schools, he only saw his father during summer vacations. As he grew up, they went fishing together and boxed. When Hemingway was too busy at work on a novel, he paid for Jack to stay at a dude ranch in Montana. Sending his love, Hemingway promised to bring his son ammunition for his rifle and asked if he should order some pistol cartridges, too. As a teenager they drank frozen daiquiris together, and spent time in Pamplona and Havana. After attending the University of Montana and Dartmouth College, Jack dropped out before taking his degree and enlisted in the US Army. He served in a military police detachment in North Africa and then, with certain strings pulled by influential family friends, was assigned to the Office of Strategic Services.
With the rank of captain, he was parachuted into Nazi-occupied France on a mission to assist the resistance. He took with him a rod, reel and fly box. On a later mission in November 1944 he was shot in the arm and shoulder, and taken prisoner. He spent the rest of the war in a PoW camp. With a fine war record, "a nice set of visible scars" and the Croix de Guerre awarded by the French government, relations between novelist and son improved.
After the war, Jack Hemingway continued his army career as a security officer in Berlin, and as liaison officer to the Third French Army Corps in Freiburg. After serving on the staff of a special intelligence course at Fort Bragg in North Carolina, Jack left the army. The transition to civilian life was difficult. He had a brief career as a stockbroker and then as a salesman of fishing supplies.
After Ernest's death, Jack was the family member most at ease with the growing public interest in the family. He explored his relations with his father in a 1986 memoir, Misadventures of a Fly Fisherman: My Life With and Without Papa. Before his death he had completed the manuscript of an as yet unpublished second volume of autobiography, A Life Worth Living, and was working on a volume of reminiscences, recipes and tales of travel, with his second wife, Angela Hovey, who survives him.
His first wife, Byra, whom he married in Paris in 1949, died in 1986. They had three daughters: Joan, Margaux, who died of a barbiturate overdose in 1996, and Hadley (Mariel), the actress.
John (Jack) Hadley Nicanor Hemingway, angler and conservationist, born October 10 1923; died December 1 2000.