Some people thought it was from generators on the houseboats. A lot of people dismissed the sound was an urban myth. Others were convinced it the source was secret underwater military testing.

The director of San Francisco’s Steinhart Aquarium had a different theory. Dr. John McCosker was one of the world’s foremost experts on White Sharks. He thought the noise sounded similar to one he heard on a beach in Mexico. It was the mating call of the male humming toadfish. The fish grew up to a foot long and could vibrate at incredible speeds producing the sound. All he needed was proof.

Channel 7 videographer Dick Epting had a boat and a plan. He arranged to take Dr. McCosker on an expedition to Richardson Bay to prove  the toadfish was the source of the annoying noise. I was invited along.

The fish is nocturnal so we headed out about 9 o’clock. Epting brought along sensitive underwater microphones. We crisscrossed the Sausalito waterfront cutting the engines frequently so we could listen for the fish. We were about to give up when McKosker picked up the distinctive drone.

Epting maneuvered the boat directly over the sound. McCosker and his assistant dropped fishing net off the back of the boat and scooped up everything in the area. We hauled the net back up and dumped the fish into the boat’s holding tank.

He picked out an ugly seven-inch long fish from the tank and held it up by its tail.

“And here you have the toadfish,” he said with a noticeable sense of satisfaction. “Mystery solved.”