North Coast kelp beds ‘like a desert’ this year
Abalone diver Richard Hayman already had been observing troubling shifts in underwater conditions off the North Coast when he found himself gazing around the ocean floor in Arena Cove with a new level of alarm.
“It’s like a desert out there,” he recalled, describing a barren underwater landscape stripped of vegetation by colonies of purple urchins that vastly outnumbered the mollusks he sought. It looked, he said, “like a fire went through.”
During 25 years of diving, Hayman had come to know the area offshore the Mendocino County town of Point Arena as a source of succulent abalones, abundant and plump with meat.
In June, he came ashore with his limit of three, despite a substantial reduction in the number of shellfish he saw. But they were so withered that, once removed from their shells, the creatures weighed less than a third of what they normally would.
“They’re starving to death,” the Calistoga man said. “It’s obvious.”
Hayman, 52, was among a dozen veteran divers who recently shared their observations at the midway point to the 2016 red abalone season, which resumes Aug. 1 after a month-long break and runs through November.
What they revealed was near consensus that all is not as usual out there, off the edge of the land, beneath the waves.
Scientists had predicted as much just before the season’s April 1 start, describing an unprecedented collapse of the North Coast’s iconic bull kelp forest and the resulting gloomy outlook for the abalone fishery and the overall ecosystem.
Divers reporting in over the past few weeks - people like Napa diver Andy Treweek, 55 - witnessed as much in some areas, where they discovered a few undersized abalone living on near-barren ocean floor.
“Usually by this time of the year, you’re swimming out over mats of kelp bed,” he said, “to the point where if you’re shore diving, it’s tough to get in some places because the kelp is so thick.”
But they also witnessed a mix of conditions and cause for hope in areas of rebounding kelp and other plant life, spots where the abalone were healthy and full, in cooler water conditions that could only be good for the system.
Many found that the ocean status varied by location, sometimes even within the distance of a few yards.
Todd Stagnaro, of Santa Cruz, said his usual dive spots around Moat Creek and the Sonoma-Mendocino county line, as well as Shelter Cove in southern Humboldt County, appeared lush and healthy, with a great diversity of wildlife.
“I don’t know where people get the idea the kelp is in trouble,” said Stagnaro, 36.
The answer comes, in part, from scientists at the California Department of Fish and Wildlife who routinely monitor offshore conditions as part of their fisheries management mission.
Over the past two years, they have been alarmed by what some have come to call a “perfect storm” of large-scale environmental impacts that included a harmful algal bloom off the Sonoma Coast in 2011 and related release of toxins that killed off large numbers of red abalone and other invertebrates.
In 2013, the spread of sea star wasting disease depleted numerous species of starfish, including two that play pivotal roles in maintaining ecosystem balance.
The elimination of starfish, which are key urchin predators, allowed for the unchecked proliferation of small, voracious purple urchins that swarmed the ocean floor in search of food.
The result was large-scale destruction of kelp and other plant life, according to marine wildlife expert Cynthia Catton, an environmental scientist with state Fish and Wildlife.
The bull kelp, which thrive in the cold upwellings typical off the North Coast, suffered further due to two years of unusually warm water conditions off the West Coast - what meteorologists and other scientist came to call the “Warm Blob” - and El Niño, which arrived last year and reinforced high temperatures.
By spring 2-16, Catton and her team estimated that the golf-ball sized urchins, which compete with abalone for food, had reached densities estimated at more than 60 times those observed in the past.
Meanwhile, aerial surveys assembled from imaging done last fall off the coastline between San Francisco and the Oregon border showed a 93 percent reduction in the surface area of the kelp forests compared with past peak years, she said.
But while most of the underwater and aerial surveys for the current year are still to come, scheduled to coincide with peak kelp growth season later this summer, Catton said preliminary dives, abalone inspections and diver reports suggest some patchy recovery of the kelp and areas where abalone seem to be doing better than others, but only in small areas.