Bar Gigantesque

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.

Known Predators:

• great white sharks (Carcharodon carcharias)
• humans (Homo sapiens)

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.

Range mass: 255.6 (high) kg.

Range length: 2.5 (high) m.

Other Physical Features: ectothermic ; bilateral symmetry

Sexual Dimorphism: sexes alike

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.

Range lifespan
Status: wild: 75 (high) years.

Typical lifespan
Status: wild: 100 (high) years.

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.

Range depth: 6 to 80 m.

Average depth: 40 m.

Habitat Regions: temperate ; saltwater or marine

Aquatic Biomes: benthic ; coastal

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

Perception Channels: visual ; tactile ; acoustic ; vibrations ; chemical

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.

US Federal List: endangered

CITES: no special status

State of Michigan List: no special status

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

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

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 ; research and education

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.

Mutualist Species:

• señoritas (Oxyjulis californica)

Commensal/Parasitic Species:

• Nerocila californica (Order Isopoda, Subphylum Crustacea)
• Cycloplectanum caballeroi (Class Monogenea, Phylum Platyhelminthes)

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.

Animal Foods: fish; mollusks; aquatic crustaceans; echinoderms

Primary Diet: carnivore (Piscivore , Eats non-insect arthropods, Molluscivore )

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

Biogeographic Regions: nearctic (Native ); pacific ocean (Native )

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)

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.

Breeding interval: Giant sea bass spawn annually, potentially engaging in multiple individual spawning events during a single spawning season.

Breeding season: Spawning occurs once a year between July to September.

Range number of offspring: 60,000,000 (high) .

Range gestation period: 24 to 36 hours.

Range age at sexual or reproductive maturity (female): 11 to 13 years.

Range age at sexual or reproductive maturity (male): 11 to 13 years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); broadcast (group) spawning; 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

Black sea bass can swim very fast for short distances (4) but are not built for sustained speed and the vast majority of their prey is caught on the sea bed (3). As the black sea bass rapidly opens its huge mouth a vacuum is produced, which draws in organisms crawling across the bottom or buried just below the surface, although some mid-water fish are also ambushed and sucked in. The diet largely consists of a range of fish such as sting rays, skates, flatfish, small sharks, as well as various crustaceans and octopus and squid (3). Black sea bass mature at seven to ten years. Large spawning aggregations form over the period of June to September, and remain together for a period of one to two months (1). Large females are capable of producing enormous numbers of eggs, up to 60 million or more, which hatch in around 24 to 36 hours. The larvae then drift around feeding on plankton for about a month before becoming bottom-dwelling juveniles (3). Remarkably, individuals have been known to live to an age of at least 70 years (2).

The black sea bass has been protected in California since 1981 and in Mexico since 1992. Both commercial and recreational fishing of this species were prohibited in California in 1981, although two fish per angler per trip are allowed to be caught south of the U.S.-Mexican border and one fish per trip to be taken incidentally by commercial fishermen. The law also limited the amount of black sea bass that could be caught in Mexican waters and landed in California (1). Although these laws have prevented commercial fishermen from targeting and profiting from these fish, they have failed to protect the habitats occupied by the species from fishing and have probably done little to reduce incidental mortality, since black sea bass entangled in nets have simply been discarded back into the sea (5). Indeed, many fish in spawning aggregations in the summer have been caught and released, frequently receiving injuries in the process (6). However, the banning of gill nets in California in 1990 has probably helped significantly reduce the incidental mortality of this species, and anecdotal data suggest that numbers may be beginning to rebound (1) (5). Nevertheless, either voluntary or imposed seasonal and/or area closures would undoubtedly help further minimise incidental mortalities and greatly aid the recovery of this magnificent and dramatic giant of the sea (3) (6).

As implied by its alternative name of giant sea bass, the most dramatic feature of this fish is its conspicuous size, with the largest individual recorded reaching a phenomenal 255.6 kg – a true giant of the ocean (2) (3)! The bulky, robust fish has a large mouth, small teeth and a distinctive single, strongly-notched dorsal fin (4). Almost as impressive as its size is the variation in colour displayed by this species. Juveniles start out life as a bright orange colour with black spots, with the orange turning a more bronzy purple as the individual grows and the spots fading as the fish gets darker. Large adults often appear solid black to grey, with a white underside, but retain the ability to display large black spots. Indeed, black sea bass are in fact capable of rapid and dramatic colour changes, from dark above and light below to displaying white mottling or simply changing from jet black to pale grey. These colour changes are thought to act as a form of communication between individuals or to be an indication of stress (3).

Adults typically inhabit rocky bottoms near kelp beds in waters deeper than 30 m, while juveniles usually occur in and around kelp beds as well as sandy bottom areas at depths of 12 to 21 m (1).

Found in the Eastern Pacific, from Humboldt Bay in California, U.S.A., to the tip of Baja in Mexico, as well as being found in the northern half of the Gulf of California. Recorded also in the coastal waters of northern Japan, although this occurrence is suspected to represent a misidentification (1).

Classified as Critically Endangered (CR A1bd) on the IUCN Red List 2004 (1).

The black sea bass has been massively over-fished in both California and Mexican waters, leaving this water giant Critically Endangered. Indeed, so dramatic were these declines that between 1932 and 1980 commercial landings diminished from 115 tonnes biomass to 5 tonnes in Californian waters, and from 363 tonnes to 12 tonnes in Mexican waters. The species' limited distribution, large size and aggregation in spawning areas made it an easy target for fisheries (1). Unfortunately, its slow growth and late onset of sexual maturity make the fish extremely vulnerable to population collapses from over-fishing, and slow to recover (5). Additionally, it appears that the black sea bass may also be suffering from toxin poisoning. Sediments along the coast of California have been found to carry very high levels of toxins such as DDE and PCB, with an area off the Palos Verdes peninsula thought to contain possibly the highest loads of DDE (a breakdown product of DDT) in the world's oceans. The toxins cannot be broken down so, as a mid-level predator, black sea bass ingest the cumulative toxins in increased concentrations from the food chain below it, and have been found to be carrying extremely high body burdens of DDE and PCB in southern California. The chemicals have been recorded to interfere with normal reproductive biology in other species of fish, as well as amphibians, reptiles and birds, but more research is needed into the effects they are having on this giant fish and its process of recovery in California (3).

Pelagic spawner (Ref. 56049).

Occur on rock bottoms; near shore, outside kelp beds and along drop-offs (Ref. 2850). Large specimens usually found deeper than 30 m, small ones over sand and in kelp beds mostly from 12-21 m (Ref. 2850). Aggregate for spawning in summer (Ref. 2850). Pelagic spawners (Ref. 56049). Longevity of 90 to 100 years (Ref. 56049) stemmed from speculation on the age of a 557 lb fish caught in 1962, but the oldest age determined from otoliths of a 435 lb fish was 72 to75 years (Ref. 4563). Validated age so far is up to >50 years using bomb radiocarbon (A.H. Andrews, pers. comm.)

fisheries: commercial; gamefish: yes

The giant sea bass (Stereolepis gigas) is a fish native to the North Pacific Ocean. Although commonly referred to as a giant sea bass, black sea bass or giant black sea bass, it is actually a wreckfish in the family Polyprionidae rather than in the sea bass family Serranidae.