JJ Hooper's second-half hat-trick handed Grimsby a 3-0 victory at Forest Green on the final day of the League Two season.Hooper broke the deadlock on 51 minutes when he stretched to toe-end the ball over the line. He grabbed his second on 83 minutes with a sumptuous angled strike and six minutes later completed his smash and grab with a howitzer from 25 yards.With both sides safe from any lingering relegation fears, the game was played out in a pedestrian fashion.Forest Green created the better first-half chances but found Grimsby keeper James McKeown in fine form as he denied 25-goal striker Christian Doidge and then clawed away a Scott Laird free-kick. He remained resolute as he somehow miraculously scooped away a Charlie Cooper header.Referee Seb Stockbridge hobbled off to be replaced by fourth official Adam Bromley with 20 minutes to go.Hooper turned up the heat in the second half with his hat-trick to leave Grimsby unbeaten in their last five games, finishing 18th in the final league standings, with Forest Green ending their first season in League Two in 21st.