A two-out throwing error by the New Hampshire Fisher Cats opened the floodgates for the Portland Sea Dogs in a 5-2 win Friday night at Hadlock Field.

With one Portland runner on and two outs in the third inning, Fisher Cats shortstop Kevin Nolan fielded Deven Marrero’s grounder but threw wildly to first. The Sea Dogs followed with three run-producing hits from Travis Shaw, Carlos Rivero and Blake Swihart (two-run double) for a 4-0 lead.

Rivero added another RBI single in the seventh.

That was enough for Brian Johnson (2-0), who allowed two runs on six hits in his Hadlock Field debut. His ERA is 1.59 after two Double-A starts.

Noe Ramirez pitched three scoreless innings for his second save.

New Hampshire starter Deck McGuire (3-4) took the loss, although he did not allow an earned run.

The Sea Dogs (21-11) continue to lead the Eastern League’s East Division, while the Fisher Cats (14-19) are fifth among six teams.

NOTES: Mookie Betts went 1 for 3 with a walk, extending his on-base streak to 61 games. He is batting .392. … Shaw continues to lead the team with 26 RBI. … The announced paid attendance was 6,810.