Hatch scored a game-high 24 points and hauled down 14 rebounds, while Ryan finished with 13 points and 13 boards, but it wasn't enough as the Tritons fell behind early and never recovered.
Monterey Bay shot 46% (27-58) from the field and led by as many as 15 points, evening its season record to 2-2 and improving to 1-1 in CCAA play.
UCSD, which has now lost two straight conference openers, falls to 5-2 overall. The Tritons had won three straight coming in following a strong showing at the 4th Annual Notre Dame de Namur Thanksgiving Classic in Belmont last weekend.
Davion Berry scored 22 points and dished out eight assists to pace the Otters, who never trailed. He finished 7-of-14 from the field. Ian Hosford scored 18 points on 8-of-15 shooting, while Brandon Ward added 11 points and four assists.
Hatch led four players in double figures for UCSD, finishing 10-of-18 from the floor, while Ryan converted 3-of-7 attempts and hit 7-of-8 at the foul line. Justin Brue tallied 13 points on 6-of-10 shooting to reach double figures for the third time in the last four games and James McCann chipped in with 11.
The Tritons shot 44% (24-54) for the game, but converted just 6-of-20 attempts in the opening half, 30%. UCSD was dominant in the rebounding department, posting a commanding 51-22 advantage, but CSUMB scored 15 points on 14 Triton turnovers.
Monterey Bay led 17-8 nearly 10 minutes into the opening half and pushed the lead 25-11 on back-to-back baskets from Hosford. UCSD was able to trim the lead to eight at 29-21 following two free throws from Ryan and a Hatch jumper, but the Otters closed the period on a 7-2 run to take a 36-23 halftime lead.
The Tritons' 23 points at the break marked their lowest total for a half this season.
"We definitely struggled in the first half and it cost us," fourth-year head coach Chris Carlson said. "We've been fortunate enough to overcome a couple of poor starts so far this season, but when you fall behind by 15 points on the road, its very difficult to come back."
CSUMB took its biggest lead at 51-36 on a jumper by Brandon Ward with 13 minutes remaining and the margin remained at 15 when two free throws from Berry made it 61-46 four minutes later.
UCSD would not roll over though, using a 13-5 run to pull within 66-59 with 5:32 left to play. Hatch scored seven points during the stretch, as the Tritons began to heat up late in the second half. UCSD continued to chip away at the lead, cutting the deficit to just three at 70-67 following a McCann three and a Brue jumper with 55 seconds left.
That would be as close as UCSD would get though, as Berry converted on the Otters' next trip and Derrick Anderson hit two free throws after a Triton turnover to push the lead back to seven, 74-67, with 22 ticks left. With UCSD trailing 75-69, Hatch would knock down a three with four seconds remaining to bring the Tritons within three at the final horn.
UCSD hit 18-of-34 shots in the second half, 53%, but it wasn't enough to overcome the big deficit.
The Tritons will now travel to San Francisco State to take on the Gators on Saturday night. Tipoff is scheduled for 7:30 p.m. following the women's matchup.