Pair of UCSB researchers to explain the economic value of the oversized fish at lecture today in Ventura
In one of the first studies of its kind, UCSB researchers Ana Sofia Guerra and Francis Joyce are identifying the movement of individual giant sea bass using new computer imaging technology paired with photographs taken by recreational divers.
The duo will be sharing some of their insight during a lecture tonight at the Channel Islands National Park Robert J. Lagomarsino Visitor Center, 1901 Spinnaker Drive in Ventura.
Their research evaluated the high economic value of the giant sea bass to the recreational diving industry. Viewed as an apex predator, or one of the top predators in the kelp forest, the giant sea bass plays a key role in the local marine ecosystem in Southern California. The populations remain critically low, however, due to overfishing in decades past and the species is listed as critically endangered by the International Union for Conservation of Nature.
The commercial fishery of giant sea bass peaked around 1932 and completely collapsed by the 1970s. In 1981, the state closed down the fishery to recreational fishing and the fish can no longer be targeted. In two specific California fisheries, the halibut and white sea bass fisheries, if a fisher were to accidentally catch one they can only retain one, Ms. Guerra explained.
Giant sea bass are understudied despite being the largest bony fish found along the California coast. They can grow to over 700 pounds and up to seven feet in length and can live up to 70 years.
Ms. Guerra formerly worked in Australia where they have an ecologically similar fish called the Potato Cod. There is a dive site where divers visit just to see that fish, which she said sparked her interest in the giant sea bass.
“It turns out it’s hard to find an endangered fish,” she explained. “There’s just not a lot of them.”
One of the more popular local dive spots, Casino Point near Catalina Island, is known as a giant sea bass aggregation area. Researchers at California State Longbeach have been tagging giant sea bass with what are known as “jab tags,” which then transmits an acoustic signal to previously placed receivers which record their location.
“You can’t tag every fish but you can’t have a receiver everywhere,” Mr. Joyce explained.
Last July, the researchers launched a citizen science projects where local divers can share their data or photos of the fish. Mr. Joyce and Ms. Guerra are then able to use a computer vision algorithm to find a potential match.
“It makes the process way more efficient and frankly effective because we just wouldn’t have that at all,” Mr. Joyce explained.
Despite the value of the species, because of the collapse in population biologists were unable to properly study them. Researchers are still grappling with the basic biology, their age structure, population trends and the “effective population size,” which examines the genetic diversity to determine the idealized population, Mr. Joyce said.
“We have a pretty good sense that the species is recovering and this moratorium has been effective, but the abundance is just a shadow of what it was,” he said.
It’s not uncommon to see a giant sea bass in local waters, but being able to offer more information is still tough to do, Ms. Guerra said.
“People talk about them a lot and they’re an exciting thing to see in the kelp forest when you’re diving,” she said. “But then it’s this mix of they’re excited to see them but we don’t know what to tell you about them.”
Ms. Guerra, 28, is in her third year of her PhD focusing on the intersection of animal behavior and human interaction. She also studies the behavior and ecology of animal aggregations, including schooling fish on coral reefs, and western gulls nesting on the Channel Islands.
Mr. Joyce, 27, is a researcher at the Benioff Ocean Initiative at UCSB where he focuses on a wide array of marine conservation topics, from threatened species in the Santa Barbara Channel to global analyses of industrial fishing activity. He grew up in Costa Rica and went to Bowdoin College in Brunswick, ME. He moved to Santa Barbara in 2014.
Tonight’s program begins at 7 p.m. and is free and open to the public. The talk is part of the “From Shore to Sea” lecture series sponsored by the Channel Islands National Park and is aimed to further understand the current research on the Channel Islands and surrounding waters.
The lecture series is held on the second Thursday of each month March through May and September through November. The lecture can be viewed live online by searching “Shore to Sea lecture series.”