From uscode.house.gov, Joint Resolution, Public Law 92-285:

In 1972, Congress resolved, “That the President of the United States declare the fourth Saturday of September 1972 as ‘National Hunting and Fishing Day’ to provide that deserved national recognition, to recognize the esthetic, health and recreational virtues of hunting and fishing, to dramatize the continued need for gun and boat safety and to rededicate ourselves to the conservation and respectful use of our wildlife and natural resources.”

From The American Presidency Project, Proclamation 10453—National Hunting and Fishing Day, 2022, “Every year, tens of millions of Americans take to the great outdoors to hunt and fish. These time-honored traditions offer opportunities for sport and leisure, put food on our tables, and bring families and friends together. They embody the American spirit of adventure and resourcefulness and inspire gratitude for the beauty and bounty of our natural world. On National Hunting and Fishing Day, we celebrate America's hunters and anglers for strengthening our communities and recommit ourselves to conserving lands and waters so future generations can enjoy these beloved pastimes.”