At first glance, these snail-like bottom dwellers don’t strike you as much. But their unassuming shells hold a secret brilliance, and the creatures inside share a fascinating, yet tragic, history.
Abalone are large gastropods that have round, oval-shaped shells with two or three spirals, the last creating an ear-like shape, giving them the nickname “ear-shell.” Outside, the shells are a plain reddish-brown or black depending on the species, while the insides are beautifully iridescent, ranging from silvery white mother of pearl to a shiny green-blue. Using what is called a muscular foot, the mollusks move along rocks searching for the different types of algae they eat. The muscular foot also allows them to firmly attach to surfaces, preventing themselves from being disturbed by predators or wave action. As the animal grows it develops open holes along the edge of its shell eventually having three to nine, depending on the species. These holes are used for respiration, sanitation, and reproduction. They reproduce through broadcast spawning in which they release their eggs and sperm into the water. However, this method of reproduction becomes less successful when the animals are few and far between, which sadly is now the case for California’s abalone.
In California we have seven species of abalone: red, pink, green, black, white, pinto and flat. These interesting creatures, once abundant off the California coast, have endured decades of threats including overfishing, disease, and environmental changes that have caused their populations to plummet. Because of their beautiful shells and value to cuisine, abalone have been a part of Californian culture for centuries. They were fished, traded, and eaten by indigenous tribes, colonizing Spaniards, and 19th century Chinese and Japanese immigrants. As the 20th century brought developments to scuba diving, abalone’s popularity peaked. Both sport and commercial fishing throughout the 1950s, 60s, and 70s dealt a hefty blow to the mollusks’ population. According to NOAA, white abalone catch dropped from “roughly 143,000 pounds per year to just 5,000 pounds per year in less than a decade”. Then, the 80s and 90s brought severe El Niños that caused waters to warm and nutrients to decrease. This harmed the Southern California kelp beds and in turn abalone that depend on the kelp for food. The abalone’s next adversity came in the form of disease. Withering foot syndrome or withering syndrome (WS) was first identified in the 1980s and has two major mechanisms that leads to abalone mortality First, it inhibits the production of an abalone’s digestive enzymes, which leads to starvation. Secondly, it atrophies, or shrivels, their muscular foot, until they are unable to latch onto rocks, which leads to predation. This cruel disease decimated abalone populations in the 80s and 90s, specifically the black abalone.
Besides their social, cultural, and economic importance, abalone also play an important ecological role in keeping the highly diverse kelp forest habitat healthy. By clearing some areas of kelp, it allows different species to establish and encourages kelp diversity. This in turn boosts diversity of the countless species depending on the kelp for food and shelter. In addition, they are the main competitor of sea urchins who also feed on kelp. Unfortunately, due to lack of predation and competition, the urchin population has been rising out of control, eating through the kelp and creating urchin barrens. If the abalone populations were at normal levels, they would regulate sea urchin populations and their capacity to overgraze on kelp. However, we already know that is not currently the case...
Due to their history studded with struggles that caused population decline, protections have been placed on California's abalone. Seeing the impact humans were causing, the commercial black abalone fishery was closed in 1993, followed by green, pink, and white in 1996, and finally in 1997 came the end of all commercial fishing of abalone. The only fishery remaining to this day is the recreational fishery for red abalone north of San Francisco Bay. However, after sea urchin booms and kelp collapse caused a number of red abalone to die of starvation, this last fishery was closed in 2017, effective until 2026. In addition to restrictions on fishing, two of California’s abalone species, white and black, have been federally listed as endangered in 2001 and 2009, respectively. Sadly, fishery closures and ESA listings might have come too late, as abalone populations have not shown signs of recovery. It has become clear that because of all they have been through, abalone will not be able to recover on their own.
Despite the abalone’s long string of misfortune, conservationists have not given up on this special shellfish. There are several efforts to reverse the impact humans have caused and restore abalone populations to the shores of California. The California Department of Fish and Wildlife adopted the Abalone Recovery and Management Plan in 2005. In addition, white and black abalone each have specific recovery plans through the ESA which were published in 2008 and 2020, respectively. The main strategies of all of these plans are to protect wild populations and their habitat and to undergo captive breeding and out-planting programs to supplement populations. This is no easy task: breeding in labs requires just the right chemical cues to trigger the abalone’s broadcast spawning and once the abalone have been out-planted there is a low chance of survival. Despite these difficulties, there have been recent successes in abalone conservation. In 2019, 3,000 captive-bred, endangered white abalone were released into the wild, half near San Diego and half near LA. After years of working to spawn them in labs and practicing releases with red abalone, this was the first time white abalone, the most imperiled species, were released into the wild. NOAA, California Department of Fish and Wildlife, and Paua Marine Research Group who collaborated on this hope that some of these abalone will survive and breed to help revive the population. Locally, Get Inspired Inc has had success breeding and releasing green abalone in OC.
Abalone are unique and interesting animals that have ecological, cultural, and economic value. It is our responsibility to protect this vulnerable species and undo what decades of human caused threats have done. Hopefully, with our help, abalone can be restored to their prominence in California, perform their duties in the ecosystem, and return to the level of cultural and economic importance they once held.