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Conservation Status:  Endangered - Protected

Climate Change:  Uncertain

AquaticGiant Sea Bass

Stereolepis gigas Bony Fishes

Aquarium of the Pacific - Online Learning Center - Species Print Sheet

Giant Sea Bass
Giant sea bass in the Channel Islands Sanctuary | Courtesy of NOAA
Giant Sea Bass
Giant sea bass in the Channel Islands Sanctuary | Courtesy of NOAA

Species Overview

Giant sea bass are also known as jewfish m and black bass. When alive they can cause the dark spots that are scattered on their body to come and go but when dead, they are a uniform very dark brownish-black, hence the common name black bass. In spite of their size, they are gentle giants, easily approached by divers. Almost hunted in extinction, in 1988, the California legislature passed a law to protect them and their numbers appear to be increasing in California waters.

Species In-Depth | Print full entry

At the Aquarium

The Aquarium has three giant sea bass under a special permit from the California Department of Fish and Wildlife. The two larger ones have inhabited Blue Cavern since 1998 and we have identified them as male and female (the larger of the two) because of their spawning behavior. It is believed they may be about 30 years old based on their size and spawning behavior. The third small fish came to the Aquarium in 2012. Our aquarists believe it is a male based on behavior and interaction between it and the older giant sea bass.

Geographic Distribution

Northwest Pacific Ocean from Humboldt, California, to the Gulf of California

Habitat

Adult giant sea bass tend to inhabit the edges of nearshore areas with rock bottoms where kelp beds are nearby and drop-offs USUALLY at depths deeper than 30 m (66 ft). Juveniles are usually found near or in kelp beds on sand or mud bottoms at depths of 21 m (69 ft). Studies using acoustic tags have shown that GSB spend summer months in shallower waters, and migrate to deeper waters during the winter months

Physical Characteristics

Adult giant sea bass have a bulky robust body with a dingle strongly notched dorsal fin that fit into a groove on the back, and d a broad flat tail. The head and mouth are large. The teeth are small and in the back of the mouth.

Giant sea changes color during their lifespan. Adults are usually a grayish-black to dark brown in color on except for the belly which is much lighter. This coloration is called countershading. At times they may have dark spots on their sides. Perch-like in appearance, juveniles differ considerably from adults and are often mistaken for a different fish species. They have a sandy-red to orange body with white and dark patches scattered along the sides. The body spots are more permanent in juveniles.

Diet and Feeding

Giant sea bass are apex predators that fed on a variety of food items including crustaceans, rays, skates, squid, bony fish species (anchovies, sheephead, sand dabs, flounder, croaker), and sometimes even kelp. When feeding, a giant sea rapidly opens its mouth creating a vacuum with which to suck in water and prey. Not built for speedy swimming, much of their prey is bottom dwelling organisms.

Reproduction

Sexual maturity appears to be reached at 10 to 13 years of age. Adults gather in groups of two to twenty fish from June to September to spawn. Eggs and sperm are broadcast spawned and fertilization is external. Individuals may spawn with different mates in a single spawning season. Little is known about mating behavior or development of the planktonic larvae

Behavior

Giant sea bass can be very curious, and are known to swim near divers to investigate them. They spend much of its time in kelp forests and rocky reefs waiting to ambush prey.

Although the majority of their time is spent moving slowly, despite their size they can move very quickly for a short time. They have even been reported aiming faster than bonito over short distances. Four individuals have been tracked migrating annually between Anacapa and Catalina islands, a distance of 50 nautical miles, in about 27 hours.

Adaptation

The coloration of giant sea bass coloration helps them blend in with their surroundings in rocky reefs and the shadows of kelp forests, but their large size is their its primary protection. Their ability to make their dark spots appear and disappear is a form of camouflage.

Longevity

At least 50 years. The oldest known specimen to date was 72 years old. Two of the Aquarium’s giant sea bass are at least 16 years old.

Conservation

Giant sea bass populations are believed to be increasing slowly after years of decline but there is no scientist evidence to that effect. They are listed internationally as critically endangered and are protected in California. Legislation passed in 1988 and in force today prohibits commercial or recreational fishing for giant sea bass. If accidentally caught, they must be released. In 1990 use of gill nets near the California coast decreased the bycatch of these fish. Propagation of this species in research laboratories and other facilities has not been successful to date although fit has been attempted with recovered fertilized eggs,

These sea bass can still be caught in Mexico but they have been so overfished that they are rarely aught.

Amazing Facts

The giant sea bass can rapidly and dramatically change color, revealing white mottling or dark spots which are believed to be used in communicating stress or other signals to nearby members of the same species.

The giant sea bass is so large that when fully grown, it’s only known predators are the great white shark and human beings.