PEORIA, Ariz. -- The Mariners made their first round of cuts from Major League camp on Monday, moving nine players to the Minor League side, including hard-throwing reliever Thyago Vieira and former first-round Draft pick D.J. Peterson.
The moves leave Seattle with 53 players in big league camp, needing to get down to a final 25 by Opening Day on April 3.
Four players off the 40-man roster were moved, with left-handed reliever Paul Fry and Peterson, a corner infielder who is ranked No. 11 among Mariners prospects by MLBPipeline.com, optioned to Triple-A Tacoma. Vieira (ranked No. 12) and left-handed reliever Zac Curtis were optioned to Double-A Arkansas.
The other five players were non-roster invitees who were reassigned to the Minor League camp -- right-handed pitchers Dylan Unsworth and Peter Tago, outfielder Kyle Waldrop and catchers Marcus Littlewood and Tyler Marlette.
None of the moves were surprising. Vieira opened eyes early in camp with his 100-mph fastball, but the 23-year-old from Brazil struggled in three Cactus League outings, allowing seven hits and five runs while walking three and striking out four in 2 2/3 innings.

Peterson, the 12th overall pick in the 2013 Draft, is behind Daniel Vogelbach (ranked No. 10 in the organization) and Danny Valencia in the first-base depth chart and will return to Tacoma, where he hit .253/.307/.438 with eight homers and 35 RBIs in 46 games after a midseason promotion last year.
Fry, 24, also was optioned to Tacoma, where he was 3-1 with a 2.78 ERA in 48 games last season. Curtis, another lefty reliever, was acquired from the D-backs as part of the Taijuan Walker-Jean Segura trade.
Lefty relievers still in camp are Marc Rzepczynski, James Pazos, Dillon Overton, Nick Hagadone and Dean Kiekhefer, as well as potential starter Ariel Miranda.