A birdwatching tour boat ran aground just after leaving the Berkeley Marina on Saturday afternoon, stranding 43 people and a dog on board, authorities report.

Update, Sunday, 9:15 a.m. The captain of the Osprey is now on paid leave as Tideline conducts an internal investigation into the grounding in conjunction with the Coast Guard, according to Nathan Nayman, president of Tideline. Marine records also show that the boat was going 13.2 knots when it ran aground, not the 8-10 knots that Tideline originally said. But Nayman, who was not at the scene and spoke to his staff to find out details of the grounding, said that was a normal speed for a charter vessel.

Update, 7 p.m. The boat that ran aground Saturday afternoon was a charter boat carrying a group from the Audubon Society, said Nathan Nayman, president of Tideline. The captain took an atypical route, hugging the shore, according to Nayman.

The vessel was grounded by old wreckage on the Berkeley Reef, which Nayman said is noted on some nautical maps but not visible from the water. There are reef markers that stick out of the water, however.

Nayman said the incident happened during “dead low tide,” one of the factors that caused the boat, which was traveling a slow 8-10 knots, to run aground. The tide was lowest 10 minutes after the grounding.

There was no environmental spillage, and the boat was not damaged, Nayman said. But he said groundings can shake up those on board.

“The boat just stops, and that’s the last thing you expect when you’re traveling on the water. It’s a traumatic feeling,” he said.

A community member who was in a kayak near the grounded boat told Berkeleyside he overheard the crew discussing the marker in the water, asking: “Why did they put a channel marker right in the middle of all these rocks?”

The community member said the marker is there to alert boats about the reef in the area, not the channel.

“At extreme low tide you can stand on the Berkeley Reef rocks and keep your feet dry,” he told Berkeleyside.

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Update, 5 p.m. A birdwatching tour boat ran aground just after leaving the Berkeley Marina on Saturday afternoon, stranding 43 people and a dog on board, authorities report.

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Battalion Chief Bill Kehoe of the Berkeley Fire Department said 41 passengers and the dog were all shuttled safely to land from the Osprey, a Tideline vessel that runs a taxi service between Berkeley and San Francisco, as well as private charters. One person was treated for a minor leg injury and released.

Kehoe said the boat ran aground on the Berkeley shoal soon after leaving the marina. The shoal is marked, and the incident took place at low tide, at about 2:20 p.m. Kehoe said the U.S. Coast Guard will investigate exactly what happened.

“They ran aground because they ran out of water, but why it happened or how it happened, I’m not quite sure,” he said. Passengers reported coming to an “abrupt stop” and were unable to continue their trip. The captain contacted the Coast Guard for a tow, and Berkeley firefighters and police responded to help, along with the harbormaster’s office at the Berkeley Marina.

The coast guard and harbormaster’s office spent about an hour shuttling 41 passengers and the dog from the boat to the Berkeley launch ramp, while two crew members remained on the Osprey. The Coast Guard will now investigate the circumstances of the crash. As of about 5 p.m., all passengers had been released after providing their contact information to the Coast Guard so it can complete its investigation.

Update, 4:34 p.m. Petty Officer Cory Mendenhall, a U.S. Coast Guard spokesman from Sector San Francisco, said investigators have not yet determined what caused the ferry to run aground. He said a couple of the agency’s small boats from Yerba Buena Island had worked to shuttle passengers from the boat to land Saturday afternoon. An 87-foot USCG cutter boat called Sockeye also responded.

The boat could be a Tideline water taxi, which runs between Berkeley and San Francisco. According to vessel tracking data on the Tideline website, its Osprey boat left Berkeley at 2:19 p.m. Saturday, but stopped not far from Cesar Chavez Park.

Update, 4:15 p.m. Forty-one of 43 people have been rescued from the boat, along with one dog, authorities report. Two crew members remain on the boat to deal with the situation.

A community member identified the boat as a water taxi called “Osprey.”

Original story, 3:43 p.m. Authorities responded to Cesar Chavez Park in the Berkeley Marina on Saturday afternoon to rescue passengers on a boat that ran aground.

There were 43 people on the boat, and the U.S. Coast Guard is on scene, along with Berkeley police and firefighters. The call came in at approximately 2:40 p.m.

The boat ran aground a half-mile from shore, north of Cesar Chavez Park, but there’s no indication it is sinking. The Coast Guard and firefighters are working to come up with a rescue plan, while police are helping manage the scene and clear vehicles from the area so BFD vehicles can set up in the sailing circle turnaround area, authorities said.

Community members may notice a Coast Guard helicopter flying in the area.

There was an early report that a child was in the water, but that turned out to be false.

Two injuries have been reported but no further detail was immediately available. The passengers were being brought in as of shortly before 4 p.m.

This story was updated after publication due to the developing nature of events. Berkeleyside reporter Natalie Orenstein contributed to this story.