LIFE AT SEA 2019
HUNGRY WHALES, DISORIENTED SEA LIONS FOUND ALONG THE VENTURA COUNTY COAST
BY KIT STOLZ
n May 3, the carcass of a gray whale washed up on an Oxnard beach. An initial examination on site found that the dead whale was underweight, had been entangled in fishing gear, and had been struck by a passing ship. “He was a sub-adult, probably 4 to 6 years old,” said Michelle Berman, of the Channel Islands Cetacean Research Unit (CICRU), a Ventura County-based marine research organization. “He’d had a hard life, the poor guy. He’d been entangled in fishing gear and another group down south had freed him from the lines a few days before, but he was emaciated, and he also had gashes on his side from a ship’s propeller.” Berman said that CICRU had conducted a necropsy of the dead whale, but hadn’t yet seen the results. She said another whale washed up on a Ventura County beache this year, in the Point Mugu area, one of more than 171 whales that have been found dead along West Coast beaches this year, from Mexico up into Alaska. The long string of deaths was declared an “Unusual Mortality Event” by (NOAA), the National Oceanographic and Atmospheric Administration. The agency and its many partners in conservation have mobilized a network of scientists, fishery experts and marine wildlife lovers to better understand the nature of these whale deaths. This is not the first such setback for gray whales. The species, the best known and most visible of the whales that migrate from Mexico to Alaska and back along the West Coast, suffered a massive die-off during the 1990s, losing a total of about 6,000 individuals and putting the species itself at risk. Despite many years of research, no single cause was ever found for the die-off. Yet this century the gray whale has rebounded, experiencing what marine biologist Alisa Schulman-Janiger described as a “baby boom.” Schulman-Janiger is a whale census organizer for the American Cetacean Society-Los Angeles Chapter (ACS/LA). The species total now stands at a high-water mark in the modern era. An estimated 27,000 gray whales migrate south in the winter and north in the spring. With the resurgence of the gray whales has come a decadeslong surge in interest in whales, as seen in the growth of conservation groups such as ACS/LA, which has more than 100 members, to the business of Island Packers, which operates a small fleet of boats for whale-watching and other trips from Ventura and Channel Islands harbors to the Channel Islands. “One reason gray whales capture our attention so much is that they migrate so close to the shore,” said Schulman-Janiger, who runs the ACS/LA Gray Whale Census and Behavior Project from the South Bay area. “They’re quite visible, when they’re doing well and have lots of calves, and also when the trends are more disturbing, such as when they’re skinny with few calves. It’s easy to see what’s going on.” The northbound count of young whale calves this year, the 36th since the census has been in operation, was one of the lowest on record. “Our low northbound calf count is quite similar to the calf counts we had during the gray whale Unusual Mortality Event of 1999-2001, when we also saw many skinny grays,” reported the whale census this year.
WHY ARE GRAY WHALES DYING?
The declaration of an Unusual Mortality Event in June for the gray whale population means that a working group of scientists
— August 1, 2019
and experts organized by NOAA unexpectedly found a “significant die-off” in a marine mammal population in U.S. waters, “which demands an immediate response.” The whale census found about 25 percent of the gray whales heading north to be noticeably emaciated, with large heads and a narrowing of the body. “They were coming down the coast later than usual [in the fall], with fewer calves. They may be late because they stayed longer to feed, and then after going to Mexico, often they headed right back up north,” said Schulman-Janiger. Besides emaciation, last year an unusually high number of whales migrating along the West Coast became entangled in fishing gear. This month NOAA issued a report for 2018, finding that 46 whales, mostly humpbacks, were found entangled in fishing gear, about four times the historical average for this century. In a majority of cases where the gear could be identified, it was linked to crab fishing. Because the humpback whale is an endangered species, the Center for Biological Diversity advocacy group last year sued the California Department of Fish and Wildlife and an industry group, the Institute for Fisheries Resources, under the Endangered Species Act, alleging that they were allowing an illegal “take” of several endangered species, including the humpback whale. The suit was settled this spring when the crab industry agreed to shut down operations along the coast this year in April, three months earlier than customary. “This settlement represents the path back to normality for California’s crab fishery with built-in protections for whales and crab fishing operations under the Endangered Species Act,” said Noah Oppenheim, executive director of the Pacific Coast Federation of Fishermen’s Associations. “The past several years have been extraordinarily challenging for fishing families, and the actions we’re taking here are no exception. But in the end, we’re going to emerge together with a resilient, prosperous and protective fishery that will continue to feed California and the nation.” Humpback whales, the species most likely to become entangled in fishing gear, pursue and eat tiny anchovy, which along with some other “forage” fish along the Pacific Coast appear to be in a long decline. Studies led by William Sydeman, a scientist at the
Farallon Institute in Petaluma, California, have found that the anchovy along the coast of California has crashed in recent years, going from a high of an estimated 2 million metric tons between the years of 1960-1990, to less than 20,000 pounds in 2015, with little apparent recovery since. A series of studies shows that the anchovy spawning stock in Southern California collapsed by 99 percent from 2005-09, and remain low. Sydeman argues that as the stock of anchovy declines, the fish tend to stick close to the shore, which could explain why more humpback whales are becoming entangled in fishing gear as they pursue the fish nearer the shore. Meanwhile an international group of scientists, including Daniele Bianchi at UCLA, found in a recent climate study that as the atmosphere warms, the overall number of fish in the oceans declines, by about 5 percent per 1 degree of atmospheric warming. The study shows that already the amount of biomass in the sea has declined, and much sharper declines are forecast as atmospheric temperatures increase worldwide. “What we know is that a trend of warming due to human activities means that some natural fluctuations become more likely,” Bianchi said. “A marine heat wave becomes more likely with climate change, and a cold wave becomes less likely.” Beginning in 2014, a “marine heat wave” brought “incredibly high temperatures” to West Coast waters for about three years, according to Nathan Mantua, an oceanographer and supervisory scientist at NOAA’s Southwest Fisheries Science Center in Santa Cruz. “Top predators such as sea lions and some sea birds had trouble finding food at that time,” Mantua said. “We had a lot of abandoned sea lion pups in the rookeries [in the Channel Islands], as well as a record harmful algae bloom.” Harmful algae fosters a poison called domoic acid that can build up in many sea creatures, from the tiniest of plankton to massive blue whales. Gray whales — the most common West Coast variety — feed on tiny shrimp-like creatures on the bottom of the sea called amphipods, which they capture by filtering huge volumes of water through their baleen plates. “Harmful algae blooms can be a mortality issue for sea lions and blue whales, but for the gray whales it’s different,” explained
Ventura County Reporter | August 1, 2019