All you have to do is listen for the seagulls.
"That sound is the sound of a herring spawn," said Fish and Wildlife environmental scientist Ryan Bartling.
Bartling is closely watching the millions of fish currently making their way through the Golden Gate to spawn.
"You'll see lots of bird activity. Marine mammals sitting right along the shoreline; everybody is either after adult herring or after the eggs," said Bartling.
Bartling will crisscross the bay from the San Mateo Bridge to the Richmond-San Rafael Bridge, pulling up herring egg samples for the State Department of Fish and Wildlife.
"And then from that we can delineate the area and the boundaries and then estimate how many adult fish it took to come in and lay this amount of eggs," said Bartling.
Judging by the number he's seen, it may be a big year for the 8 to 12 inch fish.
One fisherman stopped Bartling on the water to show him a shovel full of herring eggs. A sign the fish have returned in large numbers.
Herring numbers have been declining since the early 2000s. In fact, the 2008-09 season was so bad, regulators banned fishing to allow the population to recover.
So far, many fishermen have only seen eggs in their nets, not many fish.
The same fisherman telling Bartling, "We just pulled a net for zero."
Still, all signs point to a turnaround.
One key indicator may be all those sea birds. This year's herring run has attracted a record number to the area. Bird watchers with Audubon California have counted twice as many birds at Richardson Bay in Marin County this year compared to last year.
Initial estimates by the state Fish and Wildlife Department indicate that fishermen will be allowed to catch nearly 4,000 tons of herring this year. That's nearly a thousand tons more than they were allowed to catch last year.
Some fishermen have already caught half of their limit this year.
Bartling will visit Pier 45 to see the fish come ashore, taking samples from fishermen in order to gauge the health and sustainability of the herring fishery over the next couple weeks. Those samples will be sent to a lab so that they can be checked for age and overall health.
Surprisingly, most of the fish caught in the Bay Area won't stay here, or even the United States for that matter. They will end up an ocean away in Japan where the roe is a popular New Year's delicacy. It can fetch upwards of $50 for a pound.
"The rest of the fish is either dried or sold whole and it's mostly for human consumption," said Bartling.
The herring season runs until March but closes once the annual quota has been met. The fish left in the bay are left behind to spawn another generation.
Written and Produced By Ken Miguel