Stereolepis gigas

Geographic Range

Giant sea bass inhabit coastal waters of California, from Humboldt Bay to the tip of Baja California, Mexico.

• Biogeographic Regions
• nearctic nearctic
  • native native
• pacific ocean pacific ocean
  • native native

Habitat

Juvenile giant sea bass are found at depths of 6 to 10 m, over mud flats and in coastal lagoons of southern California and the Baja California peninsula. Older juveniles and adults are found in 10 to 40 m of water over sandy bottoms, kelp beds and rocky reefs, as well as within deep ridges at depths of 70 to 80 m. Adult sea bass venture offshore of these coastal areas at various times in the year to prey on groups of spawning squid.

• Habitat Regions
• temperate temperate
• saltwater or marine saltwater or marine

• Aquatic Biomes
• benthic benthic
• coastal coastal

Physical Description

Juvenile giant sea bass are a brilliant shade of orange, with distinctive large black spots. As a fish matures, its spots deminish and its colorful exterior gradually darkens and acquires a bronzy purple hue. At full maturity, it begins to develop a white underside while the rest of its body turns black or even gray. Features characteristic of giant sea bass are dorsal spines that fit into grooves in the back and a large mouth specialized for ambush predation. Perhaps the most well-known feature of this species is its large size, with individuals historically exceeding 2 meters in length.

• Other Physical Features
• ectothermic ectothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes alike

Development

There is little specific information on the development of this species. Like in other broadcast spawning marine teleosts, fertilized eggs develop into planktonic, lechithotropic larvae that drift with coastal currents while developing into fully developed juveniles.

• Development - Life Cycle
• indeterminate growth indeterminate growth

Reproduction

Spawning behavior of giant sea bass has rarely been observed in the field. One study documented groups of 2 to 20 fish spawning in one particular area. As is the case with other broadcast spawning species, pair bonds are not formed, and individuals may spawn multiple times with several different mates.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

Male giant sea bass reach sexual maturity at about 18 kg, while females mature at sizes of 23 to 27 kg. These sizes correspond to an age of 11 to 13 years for either gender. During a three mouth spawning period from July to September, females may produce up to 60,000,000 eggs. After fertilization, the eggs absorb water and swell up, measuring up to 1.6 mm in diameter (much larger than the eggs of other bass species). Eggs are positively buoyant and float to the surface. After hatching, larvae drift and feed on plankton for about a month until they sink and start their juvenile phase.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
  • external external
• broadcast (group) spawning
• oviparous oviparous

As is the case with the majority of species that broadcast spawn, there is no parental investment beyond the energy required to produce gametes.

• Parental Investment
• no parental involvement

Lifespan/Longevity

The oldest scientifically aged fish was estimated to be 75 years old, weighing 197 kilograms. It is believed that giant sea bass may potentially live for over a century.

Behavior

Giant sea bass move among kelp beds and rocky reefs to wait for and ambush their prey. Their large mouth opens quickly, creating a vacuum that sucks the prey into the mouth. Due to its rarity in the wild, other behaviors have not been observed in this species, but it is assumed that giant sea bass might display similar behaviors to other species of a similar size, such as groupers .

• Key Behaviors
• natatorial natatorial
• diurnal diurnal
• motile motile
• sedentary sedentary
• solitary solitary

Home Range

Individuals have been repeatedly observed in the same locations, indicating that these fish reside within particular areas. However, there are no published estimates of the size of these home ranges.

Communication and Perception

This species has the ability to rapidly and dramatically change color, producing black spots and white mottling over the body. It is believed that these color changes serve as stress signals and a means of communication between conspecifics. In addition to the use of visual cues, giant sea bass are able to perceive their environment through the use of their lateral line system, which detects pressure changed and movement in surrounding waters. They can also detect dissolved chemical substances via their nares, which are analogous to nostrils in terrestrial animals.

• Communication Channels
• visual visual

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• vibrations vibrations
• chemical chemical

Food Habits

Giant sea bass mainly consume benthic invertebrates including rock crab ( Cancer antennarius ) and California spiny lobster ( Panulirus interruptus ), and will also prey on other fishes, such as round stingrays ( Urobatis halleri ), ocean whitefish ( Caulolatilus princeps ), California barracuda ( Sphyraena argentea ), kelp bass ( Paralabrax clathratus ), and barred sand bass ( Paralabrax nebulifer ). They are sit-and-wait ambush predators, that capture their prey by rapidly opening their mouth, creating a vacuum that sucks their prey into their throats.

• Primary Diet
• carnivore carnivore
  • piscivore piscivore
  • eats non-insect arthropods
  • molluscivore molluscivore

• Animal Foods
• fish
• mollusks
• aquatic crustaceans
• echinoderms

Predation

Giant sea bass are most likely to be preyed upon while they are in larval or juvenile stages, by a wide variety of marine mammals and fish. Due to their large size, only large sharks and humans have the ability to prey on adults.

Ecosystem Roles

Giant sea bass are top-level carnivores that prey on many kelp forest species of invertebrates and fish. This species is also a host for endoparasitic monogenean flukes and ectoparasitic isopods, which attach themselves to the gill rakers. Señoritas are a species of cleaner fish that share a mutualistic symbiosis with giant sea bass, removing these external crustacean parasites from the gills, skin, and inside of the mouth.

Economic Importance for Humans: Positive

Giant sea bass were one of the most economically important species of fish in the Gulf of California and were fished heavily in the 1930’s and 40’s for their value as food. As a protected species, their current value lies in ecotourism, attracting divers from around the world to coastal marine sanctuaries in California to catch a glimpse of these undersea giants.

• Positive Impacts
• ecotourism ecotourism
• research and education

Economic Importance for Humans: Negative

There are no known adverse effects of giant sea bass on humans.

Conservation Status

Giant sea bass have been protected in California since 1982, when the California State Legislature recognized the great decline in populations and banned recreational and commercial fishing for this species. However, the species can still be fished in Mexico. In 1990, Proposition 132 passed in California, banning the use of gill nets within coastal waters as a public initiative to prevent further population declines of giant sea bass.

Additional Links

Encyclopedia of Life

Contributors

Zack Helke (author), San Diego Mesa College, Antone Lahr (author), San Diego Mesa College, Paul Detwiler (editor), San Diego Mesa College, Jeremy Wright (editor), University of Michigan-Ann Arbor.

References

Bond, C. 1996. Biology of Fishes, 2nd Edition . Pacific Grove, CA: Brooks/Cole Publishing Company.

Bushing, B. 2009. "Black Sea Bass, Stereolepsis gigas " (On-line). Underwater Photography Guide. Accessed March 21, 2012 at http://www.uwphotographyguide.com/black-sea-bass .

Cornish, A. 2004. "IUCN Red List of Threatened Species" (On-line). Stereolepis gigas. Accessed March 21, 2012 at http://www.iucnredlist.org/ .

Erisman, B., O. Aburto. 2012. "Scripps Institution of Oceanography" (On-line). Reef Fish Conservation in Eastern Pacific. Accessed March 21, 2012 at http://cmbc.ucsd.edu/Research/Gulf_of_California/Reef_Fish_Conservation/ .

Hendrickx, M., M. Espinosa-Pérez. 2001. Checklist of isopods (Crustacea: Peracarida: Isopoda) from the Eastern Tropical Pacific. Belgian Journal of Zoology , 131 (1): 43-55. Accessed May 03, 2012 at http://unam.academia.edu/MichelHendrickx/Papers/515055/Checklist_of_isopods_Crustacea_Peracarida_Isopoda_from_the_Eastern_Tropical_Pacific .

Oliver, G. 1984. [Description of 2 new species of the genus Cycloplectanum Oliver, 1968 (Monogenea, Monopisthocotylea, Diplectanidae)]. Annales de Parasitologie humaine et comparée , 59/1: 31-39.

Schultze, D. 1983. California barracuda life history, fisheries, and management. CalCOFI Report , XXIV: 88-96. Accessed May 03, 2012 at http://www.calcofi.org/publications/calcofireports/v24/Vol_24_Schultze.pdf .

Sepulveda, C., S. Aalbers. 2009. "The Giant Sea Bass: Status of Biological Knowledge" (On-line). PIER. Accessed March 21, 2012 at http://www.pier.org/CA_coastal_gs_bass_biological.shtml .

2012. "Marine Sportfish Identification: Sea Bass" (On-line). California Department of Fish and Game. Accessed March 24, 2012 at http://www.dfg.ca.gov/marine/mspcont9.asp#giant .