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Sebastes serranoidesRockfish

By Thanh-Van Nguyen

Geographic Range

Olive rockfish are typically found in the Pacific Ocean off the coast of California from Del Norte County to Baja California, Mexico and is usually found around a depth of 5-100 m (Love and Westphal, 1981). These rockfish are commonly called “long-term residents”, indicating that migration is not common in this species despite changes in water conditions. (Green, Greenley and Starr, 2014). (Green, et al., 2014; Love and Westphal, 1981)

Habitat

Juvenile olive rockfish are pelagic fish, occupying a depth less than 100 m. They live close to the shore in rock reefs and kelp forests (Green, Greenley, and Starr, 2014). After a few months, however, they are found at varying depths (Love and Westphal, 1981). (Green, et al., 2014; Love and Westphal, 1981)

  • Range depth
    5 to 100 m
    16.40 to 328.08 ft

Physical Description

Sebastes serranoides is gray in color and darker dorsally. There may be visible white spots along the sides, and the fins may have a yellow tint with a dusky edge. Olive rockfish have large scales that get smaller towards the head. The head is compressed and has a long, pointed snout with a lower protruding jaw (Eigenmann and Eigenmann, 1890). The juveniles tend to be a lighter brown than the adults and have irregular spots above the lateral line. They may also have small black spots visible on the anal fins and a large black spot between dorsal spines 8 and 11. This large spot is typically absent in adult rockfish larger than 35 cm (Love, 1978). The males usually have larger eyes and longer pectoral fin. Females tend to grow larger than the males (Love, Yoklavich, and Thorsteinson, 2002). (Eigenmann and Eigenmann, 1890; Love, 1978; Love, et al., 2002)

  • Sexual Dimorphism
  • female larger

Development

Members of the Sebastes genus are known to have internal fertilization and are ovoviviparous fishes. The eggs are carried and hatch inside of the ovaries of the female (Haldorson and Love, 1991; Love and Caselle, 1998). The larvae of S. serranoides are released from December through March, the majority of which are released in January (Love and Westphal, 1981). When the larvae are released, they stay in the upper layer of the water. After a month, the larvae become pelagic juveniles (Love and Caselle, 1998). After a period of about 3 to 6 months, these fish begin to settle in waters of various depths, particularly in rocky reefs and kelp habitats (Love and Westphal, 1981). (Haldorson and Love, 1991; Love and Caselle, 1998; Love and Westphal, 1981)

Reproduction

Not much is known about the mating behaviors of olive rockfish, but it is speculated that there are several mechanisms in place to prevent cross-breeding between closely related species of Sebastes that have the same mating season. The male copulatory organs of the olive rockfish are small making it difficult for other species to fertilize the females of S. serranoides. There may also be auditory, visual, and chemical mechanisms at work that prevent cross-breeding (Love and Westphal, 1981). (Love and Westphal, 1981)

Not much is known about the reproductive general behaviors of the olive rockfish; however, the mating season of S. serranoides is believed to be from October to December, peaking in November (Love, 1978). (Love, 1978)

  • Breeding season
    October to December, peaking in November

Not much is known about the amount of parental investment of the olive rockfish after birth; however, Sebastes serranoides is an ovoviviparous, taking care of the eggs until they are ready to be hatched (Haldorson and Love, 1991; Love and Caselle, 1998). (Haldorson and Love, 1991; Love and Caselle, 1998)

  • Parental Investment
  • pre-hatching/birth
    • provisioning
      • female

Lifespan/Longevity

Rockfish are known to be slow-growing (Haldorson and Love, 1991) with a life span of around 30-50 years (Green, Greenley, and Starr, 2014). (Green, et al., 2014; Haldorson and Love, 1991)

Behavior

Olive rockfish are known to be relatively stable and are likely to stay in one area despite changes in water conditions. They are also more active during the day than at night (Green, Greenley, and Starr, 2014). At around 1 to 4 inches, juveniles are typically found in schools, but as they grow larger, they tend to prefer solitude (Limbaugh, 1955). (Green, et al., 2014; Limbaugh, 1955)

Home Range

Sebastes serranoides are typically found off the coast of California from Del Norte County to Baja California, Mexico.

Communication and Perception

Not much is known about communication of olive rockfish, but it is suspected that there are auditory, visual, and chemical mechanisms used by the fish in order to prevent cross-breeding between closely related species (Love and Westphal, 1981). (Love and Westphal, 1981)

Food Habits

The food habits of the olive rockfish change as the fish gets older and depending on the season. Juvenile rockfish are dependent on plankton and small fishes found in midwaters as a source of food. During the upwelling period, the rockfish depends more on nekton, such as squid and young rockfish. The dependence on young rockfish, however, decreases in the fall and winter due to the juveniles becoming older and are unable to be easily caught. During these seasons, other prey are targeted, such as the northern anchovy. The diet of adult rockfish mainly consists of small fishes, such as blue rockfish, young olive rockfish, and pipefish, and of substrate-oriented prey, such as octopus and squid (Love & Westphal, 1981). (Love and Westphal, 1981)

  • Animal Foods
  • fish
  • mollusks
  • aquatic crustaceans

Predation

During the upwelling period, juvenile olive rockfish, as well as other species of rockfish, are an important food source for adult rockfish and other fish species (Love and Westphal, 1981). Not much is known about what organisms prey on the adults of this species. (Love and Westphal, 1981)

Ecosystem Roles

Juvenile rockfish are an important food source for other adult rockfish and other species of fish. The adults of this species feed on small fishes and on substrate-oriented prey, such as octopus and squid (Love and Westphal, 1981). Predation is important for the regulation of the population sizes of these food sources (Johnson, 2006). The olive rockfish were thought to be replacing the kelp bass in the areas around central and northern California (Limbaugh, 1955), but this is unlikely since the two fish species do not typically rely on the same food sources (Love and Westphal, 1981). (Johnson, 2006; Limbaugh, 1955; Love and Westphal, 1981)

Economic Importance for Humans: Positive

Olive rockfish are important both as a sports fish and in the commercial fishing industry (Schroeder and Love, 2002; O’Farrell and Botsford, 2006; Love et al., 1990). (Love, et al., 1990; O'Farrell and Botsford, 2006; Schroeder and Love, 2002)

  • Positive Impacts
  • food

Economic Importance for Humans: Negative

Not much is known about the olive rockfish's negative impacts on humans.

Conservation Status

The olive rockfish is not a threatened species; however, there is evidence that the population of rockfish found off the coast of southern California has declined. There was a sharp drop in the population during the 1970s, and the population has remained at a constant low level possibly due to environmental conditions and overfishing (Love and Caselle, 1998). (Love and Caselle, 1998)

Contributors

Thanh-Van Nguyen (author), Louisiana State University, Prosanta Chakrabarty (editor), Louisiana State University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

Glossary

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

diurnal
  1. active during the day, 2. lasting for one day.
fertilization

union of egg and spermatozoan

food

A substance that provides both nutrients and energy to a living thing.

internal fertilization

fertilization takes place within the female's body

molluscivore

eats mollusks, members of Phylum Mollusca

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

ovoviviparous

reproduction in which eggs develop within the maternal body without additional nourishment from the parent and hatch within the parent or immediately after laying.

pelagic

An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).

piscivore

an animal that mainly eats fish

planktivore

an animal that mainly eats plankton

reef

structure produced by the calcium carbonate skeletons of coral polyps (Class Anthozoa). Coral reefs are found in warm, shallow oceans with low nutrient availability. They form the basis for rich communities of other invertebrates, plants, fish, and protists. The polyps live only on the reef surface. Because they depend on symbiotic photosynthetic algae, zooxanthellae, they cannot live where light does not penetrate.

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

tactile

uses touch to communicate

visual

uses sight to communicate

References

Eigenmann, C., R. Eigenmann. 1890. Description of a new species of Sebastodes. Proceedings of the California Academy of Sciences, 3: 36-38.

Green, K., A. Greenley, R. Starr. 2014. Movements of blue rockfish (Sebastes mystinus) off central California with comparisons to similar species. Plos One, 9: 1-11.

Haldorson, L., M. Love. 1991. Maturity and fecundity in the rockfishes, Sebastes spp., a review. Marine Fisheries Review, 53: 25-31.

Johnson, D. 2006. Predation, habitat complexity, and variation in density-dependent mortality of temperate reef fishes. Ecology, 87: 1179-1188.

Limbaugh, C. 1955. "Fish life in the kelp beds and the effects of kelp harvesting" (On-line pdf). Accessed November 01, 2015 at http://escholarship.org/uc/item/4w36x6mb.

Love, M., J. Caselle. 1998. Declines in nearshore rockfish recruitment and populations in the southern California Bight as measured by impingement rates in coastal electrical power generating stations. Fishery Bulletin, 96: 492-501.

Love, M., P. Morris, M. McCrae, R. Collins. 1990. Life history aspects of 19 rockfish species (Scorpaenidae: Sebastes) from the southern California Bight. NOAA Technical Report NMFS, 87: 1-38.

Love, M., W. Westphal. 1981. Growth, reproduction, and food habits of olive rockfish, Sebastes serraoides, off central California. Fishery Bulletin, 79: 533-545.

Love, M., M. Yoklavich, L. Thorsteinson. 2002. The rockfishes of the northeast Pacific. Berkeley, CA: University of California Press.

Love, M. 1978. "Aspects of the life history of the olive rockfish, Sebastes serranoides" (On-line pdf). Accessed October 06, 2015 at https://escholarship.org/uc/item/26j8768b.

O'Farrell, M., L. Botsford. 2006. Estimating the status of nearshore rochfkish (Sebastes spp.) populations with length frequency data. Ecological Applications, 16: 977-986.

Schroeder, D., M. Love. 2002. Recreational fishing and marine fish populations in Califonia. California Cooperative Oceanic Fisheries Investigations Report, 43: 182-190.

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