In-form Liam Mandeville settled the game with a superb free-kick in the third minute.
Rovers controlled the first half as they dictated the play.
But they had to dig in after the break - as Grimsby rallied and almost snatched a last-gasp equaliser through Luke Summerfield - to keep a first clean sheet in eight league games.
“Those are the games you need to win - the ones where you scrap, fight, battle,” said Ferguson.
“I thought we did it very well and it was a deserved victory and a really good win for us.
“It was a fantastic goal that won the game for us and we’ve kept a clean sheet. We’ve seen a strong, disciplined side to our game today.
“Our record in derbies last season was really poor and in many ways that was more rewarding today than the last two games when we were very good on the ball.
“They’ve got two long throws, they put the ball in the box, there were one or two hairy moments - especially the one right at the death - but you need that wee bit of luck.”