Kelp forests are among the most productive habitats in the world and are present along the west coast of North America. Kelp (order Laminariales) are large brown algae that grow vertically from the rocky substrate (hard surface where organisms live or grow) to the water surface, and they can occur in high density that resembles a forest. Their structure supports a diverse community of species, from large marine mammals (e.g., sea lions) to microscopic invertebrates (e.g., zooplankton). One of the most notable species that inhabits kelp forests along the Orange County coastline is the California sheephead (Semicossyphus pulcher). California sheephead belongs to the family Labridae (Wrasses) (FishBase). This species is native to the eastern Pacific Ocean, from Cabo San Lucas, Baja California, Mexico to Monterey Bay, California (Braje, et al., 2017). They are found in rocky nearshore reefs (6-30m depth), near and in kelp beds. Those who have gone snorkeling or diving along the Southern California coast and Santa Catalina Island may have seen this fish before.
California sheephead have an interesting life history in that they are protogynous sequential hermaphrodites (California Sea Grant). This means that they are all born as females before transitioning into males as they grow older and larger. This transition can be socially triggered by the removal of an alpha male in a harem, in which the largest female then undergoes hormonal changes to become a fully functioning male (Santa Barbara Independent). Juvenile sheephead have a reddish-orange body with dark blue spots on their fins. Adult males and females are sexually dimorphic (different) in coloration and body shape, with males having bolder coloration and larger body size. Males are black with a red-pink midsection and a white chin; they have red eyes, protruding canine teeth, and prominent sheep-like head. Females have a monochromatic pink coloration with a white chin (California Sea Grant). Under optimal conditions, sheephead have a lifespan of 20-30 years and can reach about 37 inches in length (Braje, et al., 2017).
As a diurnal species, California sheephead are active during the day and are inactive at night. They forage for hard-shelled invertebrates (e.g., sea urchins, lobsters, crabs) along with their harem members during the daytime. Sheephead use their powerful jaws and strong teeth to crack through hard shells and their pharyngeal jaws (modified throat bones) to further crush shells into smaller pieces (Braje, et al., 2017). At night, they hide in crevices and caves and cover themselves with mucus (a common behavior for wrasses) to cover their scent and avoid detection by predators such as harbor seals (Phoca vitulina), California sea lions (Zalophus californianus), and sea birds (Monterey Bay Aquarium; Animal Diversity Web).
Since California sheephead regulate the populations of voracious kelp consumers (e.g., sea urchins) through predation, they have an indirect effect on the abundance of kelp in their ecosystem (Sundberg at al., 2009). Removing California sheephead individuals from the food web can result in an overwhelming abundance of sea urchins (and other kelp grazers), which can lead to urchin barren (areas dominated by sea urchin and devoid of kelp) and ultimately harm the health of the entire habitat and its species (you can read all about sea urchins here!). Therefore, California sheephead are a keystone species in kelp forest ecosystems.
California sheephead are listed as a “Vulnerable” species by the International Union for Conservation of Nature (IUCN). Threats to their populations in Southern California include heavy commercial and recreational fishing. Since fisheries tend to catch larger fishes, they often take the males (Braje, et al., 2017). In the case of California sheephead harems, this prompts the largest females to metamorphose into males and creates a harmful pattern of younger and smaller females abruptly transitioning into males. This ultimately causes their overall population to decline.
Fortunately, California sheephead populations are now being managed through various measures including seasonal closures, bag and size restrictions, and Total Allowable Catch (TAC) limit for both commercial and recreational fisheries (California Department of Fish and Wildlife). As for the general public, being mindful of our fish consumption (for those who do eat fish) and respecting kelp forest habitats and wildlife can go a long way in helping California sheephead populations and in protecting the diversity of our local marine ecosystems. Many environmental organizations in Orange County monitor the status of our native habitats and species. OC Habitats and Get Inspired are currently monitoring the populations of purple sea urchins (Strongylocentrotus purpuratus) with the goal of restoring kelp forest ecosystems along our OC coastline. OC residents who are 18 years or older can participate in this monitoring project for free. Interested in helping? Contact OCH Staff (staff@ochabitats.org) to get started!
If you want to learn more about marine habitats and species in Orange County, OC Habitats leads informational hikes in Marine Protected Areas (MPAs) such as Little Corona Beach. Check out the OCH event schedule to learn more!