First-half goals form Kevin Ellison and Steven Old gave Morecambe a 2-0 win at struggling Grimsby.Ellison struck after 10 minutes and Old added a second before the break as the Mariners suffered a third straight defeat and saw their winless run extend to six games.The visitors took the lead when a hopeful ball into the box caught Grimsby's defenders napping, and Ellison was on hand to loop a header over debutant goalkeeper Jake Kean and into the net.Vadaine Oliver looked to pounce on a slip from Mitchell Rose a few minutes later as the visitors broke, but his shot was comfortably saved by loanee Kean.Morecambe doubled their lead as Kean flapped at a header from Ellison, resulting in the ball falling kindly for Old to nod in from just a couple of yards out.Grimsby almost pulled one back at the start of the second half as Danny Collins had his close-range header brilliantly cleared off the line.Siriki Dembele forced a good save from Barry Roche, but Grimsby could not find a way back into the game as Morecambe secured only their second away win of the season.