ALAMEDA, Calif. (CBS SF) — Crews aboard two Alameda-based Coast Guard cutters boarded three suspected drug smuggling vessels in the Eastern Pacific Ocean, seizing more than 9,000 pounds of cocaine worth an estimated $156 million.

Coast Guard officials said the Coast Guard Cutters Munro and Bertholf were involved in the operations between Jan. 26 and Feb. 1.

READ MORE: Wayne, Washtenaw County Included In DNR's First Round Of State Park Infrastructure Projects

The Munro’s crew boarded a fishing vessel suspected of smuggling illicit narcotics on Jan. 26. the boarding teams searched and discovered 1,300 pounds of cocaine concealed within the vessel.

The crew then encountered a second suspected drug smuggling vessel hours later. The Munro launched a helicopter aircrew and boarding teams and together they overtook the low-profile vessel. The boarding teams discovered 3,439 pounds of cocaine aboard the purpose-built drug smuggling vessel.

“Having back-to-back cases lasting 31 hours pushed our limits, but our crew took on the challenge,” said Capt. Blake Novak, commanding officer of the Munro.

READ MORE: Police Seek Hit-And-Run Driver That Injured Two Children In Dearborn

On Feb. 1, Bertholf’s boarding teams also boared a low-profile vessel, seizing more than 4,380 pounds of cocaine.

Cartels design low-profile vessels specifically to evade law enforcement by being difficult to detect. These vessels are built to ferry large quantities of illicit contraband while riding low in the water.

“The crew continues to impress me as they rise above challenges, stand a taut watch, and conduct themselves in a professional manner as we go about our business of stemming the flow of narcotics in the Eastern Pacific,” said Capt. Brian Anderson, commanding officer of the Bertholf.

MORE NEWS: Two People Killed After Car Attempts To Outrun Amtrak Train in Detroit

Nine suspected traffickers were taken into custody.