Calvin Johnson reportedly told the Lions he plans to retire

Detroit Lions wide receiver Calvin Johnson has reportedly informed head coach Jim Caldwell that he plans on retiring this offseason, according to ESPN's Adam Schefter.

Schefter's report comes after a month of speculation revolving around the receiver's future. Johnson, who will turn 31 in September, just finished his ninth NFL season -- all coming with the Lions.

According to the report, Johnson told family members prior to the 2015 season that he planned on it being his last. He reiterated this point to Caldwell after the team's season ended on Jan. 3, but the team is holding on to hope that Johnson will reconsider.

Lingering injuries and "general body soreness" have driven Johnson to this point, according to the report, and he only shared his retirement plans with two teammates during the season: quarterback Matthew Stafford and linebacker Stephen Tulloch.

The team still hasn't received official confirmation from Johnson, and Caldwell told him not to rush into a decision. But an ESPN source close to the six-time Pro Bowler told Schefter, "He's pretty content with his decision" to retire.

Should he end his career after nine seasons, his 83 touchdown catches would rank 22nd all-time, and his 11,619 yards would go down as 27th-most ever.

See the richest players of the 2015 NFL season

More from AOL Sports:
Johnny Manziel has another 'altercation' with girlfriend
Michael Phelps strips off, flashes gold medals to distract basketball player
NFL says concussions way up; no release of full injury data