Nearshore Fishes

weighing of white sea bass, CDFW CRFS photo; Guad Dunes Surfperch Derby, CDFW photo by Ken Oda; recreational angler, CDFW photo by Ken Oda; angler interview, CDFW photo by Colin Brennan; Marina del Rey Halibut Derby, CDFW photo by Sabrina Bell

California Halibut

California halibut are large, toothed flatfish found in nearshore waters and may be described as being an estuarine-inner shelf species. They are visual ambush predators that range from Magdalena Bay, Baja California north to the Quillayute River in Washington, being most abundant from central California to Baja California. Though they may be found in ocean waters as deep as 600 ft (183 m), they are most often caught by anglers in 10 to 90 ft (3 to 27 m) of water. California halibut are broadcast spawners, and eggs are fertilized externally. Adults migrate from the continental shelf into shallow coastal waters and bays before spawning, usually from February through September. Eggs are pelagic (free floating). Larvae develop with one eye on each side of the head. As California halibut mature and reach the post-larval stage (20-29 days), one eye migrates to the other side so that both eyes are on the same side. California halibut may be right- or left-eyed.

Species Identification

California halibut are usually uniformly brown to brownish-black on the eyed side, and have the ability to change skin color patterns to camouflage with the substrate. They may have white spots, especially juveniles, which often fade after death. The non-eyed side is usually entirely white, though some mottling may occur. The lateral line is most distinctive and is highly arched above the pectoral fin. The mouth is large with conical teeth. The maxilla (top jaw bone) extends beyond the eye. There are less than 77 soft dorsal rays.

Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Pleuronectiformes
Family: Paralichthyidae
Genus: Paralichthys
Species: californicus

California halibut - a flat, bottom fish

Pacific halibut vs. California halibut

In the Pacific halibut (Hippoglossus stenolepis), the maxilla extends only to the front edge of the eye, whereas the maxilla extends beyond the eye in California halibut. Pacific halibut have more than 80 soft dorsal rays and the eyes are always on the right side of the head whereas California halibut will have less than 77 soft dorsal rays and the eyes may be on the right or left side (dextral or sinistral).

Studies

California halibut is one of the most important recreational species in Southern California, and commercially-fished species among the state-managed fisheries. The Southern California Fisheries Research and Management Project obtains Essential Fishery Information (EFI) such as length, weight, age, and sex of halibut from commercial landings in Southern California ports and from sport-caught fish. The Northern and Central California Finfish Research and Management Project obtains basic length, weight, age, and reproductive information from sampled landings in central and southern California ports. Choose from the links below for more information about California halibut.

  • Fishery Independent Trawl Surveys
    Staff began collecting an index of California halibut abundance in Southern California in 2018.
  • link opens in new windowGreen sturgeon post-release impacts in central California halibut trawl fishery: This project is collaborating with central California commercial halibut trawl fishermen, NOAA Fisheries Santa Cruz office, and the West Coast Groundfish Observer Program, to place satellite tags on green sturgeon caught as bycatch in the halibut trawl fishery.
  • Cruise Report: California Halibut (Paralichthys californicus) CDFW/NMFS Light Touch Trawl Survey of North Monterey Bay (2013)
  • link opens in new windowCruise Report (PDF): California Halibut (Paralichthys californicus) Trawl Survey of North Monterey Bay (2010)
  • link opens in new windowCruise Report (PDF): Southern California Fishery-Independent Halibut Trawl Survey (2008)
  • link opens in new windowCruise Report (PDF): Fishery-Independent Trawl Survey in Monterey Bay (2007)
  • Length- and age-at-maturity study: The Project was awarded a grant through the Bay-Delta Sport Fishing Enhancement Stamp Fund for research to determine length- and age-at-maturity for male and female California halibut within San Francisco Bay. In a collaborative partnership with Moss Landing Marine Labs, California halibut maturity was additionally studied from fish collected along the open central California coast. The results from these studies were combined to assess maturity, using histological parameters, in the central California region as a whole and have now been published in an article available in the journal link opens in new windowCalifornia Fish and Game (PDF). Comprehensive estimates of length- and age-at-maturity, using macroscopic parameters, for halibut were previously available from the southern California region (Love and Brooks 1990). Using those data, the article discusses regional differences in maturation between southern and central California. Additionally detailed descriptions useful in determining reproductive phase and spawning state for California halibut are presented.
    • Data summary:
      • In central California, 50% of males were mature by 27.0 cm (1.1 yr) and 50% of females were mature by 47.3 cm (2.6 yr), according to histological parameters.
      • In southern California, 50% of males were mature by 22.7 cm (1.3 yr) and 50% of females were mature by 47.1 cm (4.3 yr), according to macroscopic parameters.
  • San Francisco Bay Hooking Mortality Study: In 2009 CDFW staff completed the second year of a hooking mortality study for halibut initiated in 2008 within San Francisco Bay. This study evaluated the potential impact of various gear types on released halibut. Upon landing, the type of hook, hooking location, and length of the fish were recorded. Selected halibut were retained at the Aquarium of the Bay for observation. link opens in new windowView the unpublished study report (PDF).
  • Statewide Stock Assessment: The CDFW has collected and summarized recent and historical data for use in a statewide stock assessment for California halibut. Historical and current catch and biological data were included. This is the first statewide evaluation of the California halibut resource. View the completed assessment.
  • link opens in new windowCalifornia Halibut Sex Determination Guide (PDF)
  • link opens in new windowExternal Sex Determination of California Halibut (Video)
    CDFW instructional video by Kristine Lesyna

California Halibut Trawl Surveys

The goal of this study is to develop a fishery-independent index of juvenile California Halibut abundance. The index can be used to inform management on the status of the resource, and provide predictions for recruitment to the fishery in Southern California. Because juvenile halibut spend their first couple of years exclusively in shallow offshore locations and embayments, conducting swept area trawl surveys can be used to evaluate distribution, relative abundance, and expected contributions to the fishery. 

Starting in April 2018, CDFW staff began conducting biannual trawl surveys in the spring and fall months using a 25 ft. otter trawl. Trawls are deployed in 13 primary locations ranging from San Diego to Los Angeles. Ten 10-minute trawl surveys are conducted in 8 to 20 ft. depths at each location, and all of the fish caught are identified and measured. All halibut greater than 3 inches are internally tagged with a Passive Integrator Transponder (PIT) tag that allows for identification of specific individuals when recaptured. This study uses similar methods to those used by CDFW from 1993-1995, including net parameters, survey locations, depths, and trawl times. Following these past protocols presents the opportunity to evaluate current population abundance relative to results obtained in the 1990s and establishes a new baseline for comparison to future surveys. 

Across two years and four sampling surveys, the average halibut abundance varied greatly among locations but was similar between years (Figure 1); there was no significant difference between spring and fall surveys. Protected locations like bays and harbors yield a significantly higher number of juvenile halibut per area compared to coastal locations. Halibut are the third most abundant species caught while trawling, although they are the most abundant fisheries species (Table 1).

Comparing the most recent (2018-2019) and past (1993-1995) study periods, halibut density was similar among all years except for 1994 which was significantly higher at all but one location (Figure 2). It is also interesting that commercial halibut landings between these two time periods were also similar (Figure 3). Both recent and past trawl study time periods occurred during similar warm temperature regimes, with 1994-1995 being classified as a 'moderate' El Nino and 2018-2019 classified as a 'weak' El Nino. Based on the significant greater number of juvenile halibut in 1994 at a size of approximately 6-8 inches (~1 year old), CDFW would have predicted a large increase in commercial landings of halibut 5-7 years later (1999-2001) when they would be approximately 6-8 years old and 25-29 inches in length, the typical size landed in the Southern California fishery.

A chart showing the average number of halibut observed at each location for 2018 and 2019 surveys
Figure 1. Average number of halibut observed per 300m2 at each location. Black bars represent the average of spring and fall surveys in 2018 and white bars represent 2019 surveys. The error bars represent one standard error.

A chart showing the average number of halibut observed at each location for all survey years
Figure 2. Average number of halibut observed per 300m2 at each location. The white, grey, and black bars indicate 1990’s data, and blue shaded bars represent the more recent survey years. The error bars represent one standard error.

A chart showing commercial landings in pounds of California halibut in Southern California from 1990 to 2019
Figure 3. Commercial landings in pounds of California halibut in Southern California from 1990 to 2019. The large black circles represent the time periods of the past (1993-1995) and more recent (2018-2019) trawl surveys. The asterisk indicates when a predicted spike in landings would be seen based on the 1994 trawl data.

Table 1. The total number of species sampled across all locations for 2018 and 2019 sampling periods, ranked in order of most to least abundant.

Species Total Number Caught
Queenfish 2,747
Sanddab species 1,501
White Croaker 1,123
California Halibut 978
Perch species 768
Round Stingray 516
California Lizardfish 414
Barred Sand Bass 238
Yellowfin Croaker 181
Pipefish species 162
California Tonguefish 135
Topsmelt 128
California Corbina 111
Spotted Turbot 104
Fantail Sole 82
Bat Ray 76
Diamond Turbot 74
Thornback Ray 66
Spotfin Croaker 53
Spotted Sand Bass 41
Kelp Bass 26
Sargo   22
Giant Kelpfish 21
California Butterfly Ray 20
Curlfin Sole 18
Pacific Jack Mackerel  17
White Seabass 14
Unidentified Croaker  10
Speckled Midshipman 10
Pacific Sardine 10
California Scorpionfish 10
Hornyhead Turbot 9
Horn Shark 8
Rock Wrasse 7
Shovelnose Guitarfish 5
Pacific Angel Shark 5
Pacific Staghorn Sculpin 4
Salema 3
Leopard Shark 3
Torpedo Ray 2
Cusk Eel 2
Treefish 1
Jack Smelt 1
Cabezon 1
Basketweave Cusk-Eel 1

Ageing Studies

In 2009 the Project began to determine the age of California halibut using thin sections of otoliths (ear bones) collected from fish sampled primarily in the commercial and recreational fisheries. Otoliths are mounted in epoxy resin, thin sections are cut using a diamond saw, and ages are determined under high magnification. Two readers independently age each otolith and when agreement is reached, the age, length, sex, and other sampling data are entered into a database. As of August 2013 more than 1,000 otoliths have been aged from southern and central California. The photos below show three of the best thin sectioned halibut otoliths we have aged, from top to bottom: a 7-year old female, a 9-year old female, and a 12-year old female, all sampled from the San Francisco Bay recreational fishery from 2012 to 2014. Most otoliths are not nearly as easy to read as these are.

Otolith section from 7-year-old California halibut. CDFW file photo.
Otolith section from 9-year-old California halibut. CDFW file photo.
Otolith section from 12-year-old California halibut. CDFW file photo.

Recruitment Studies

link opens in new windowRelative Contribution of Local Recruitment to the San Francisco Bay California Halibut (Paralichthys californicus) Fishery Inside the Golden Gate (PDF)
by Max Fish, Bay-Delta Study, CDFW

Project Resources

Environmental Scientist Travis Tanaka with a California halibut captured during a research cruise. CDFW file photo.

Environmental Scientist Kristine Lesyna examines a California halibut. Photo credit: Angler James Garvey.

Halibut caught during Hooking Mortality Study. CDFW photo by Adrienne Vincent.

California halibut. Photo credit: CDFW/MARE

White Seabass

The white seabass (Atractoscion nobilis) is the largest member of the Sciaenid family found in California waters. In addition to being a popular sport fish, white seabass is also targeted by a commercial fishery. There have been commercial and recreational fisheries for white seabass in California since the 1890s. The fisheries occur primarily in Southern California but in some years may extend to central California. The commercial fisheries use primarily drift gill nets but some fish are taken on hook-and-line. The current sport angling record is a 78-pound fish caught in Monterey Bay on April 4, 2002 by David L. Sternberg. White seabass are also taken by divers. The current sport diving record is for a 93-pound, 4-ounce fish caught in Malibu on September 17, 2007 by Bill Ernst while freediving.

Species Identification

an elongated white and silver fish

Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Perciformes
Family: Sciaenidae
Genus: Atractoscion
Species: nobilis

The white seabass (Atractoscion nobilis) has an elongated body, large mouth, and a raised ridge along the length of its belly. It is grey-blue to copper on its back, with dark specks on its sides and a silver belly. It has a black spot on the inner base of its pectoral fins. Young white seabass have dark bars on the side. White seabass may be confused with the shortfin corvina (which has 1 or 2 large canine teeth on each side of the upper jaw) or the queenfish (which has a wider gap between the dorsal fins and more soft rays in its anal fin).

Maturity

CDFW staff are collecting white seabass from areas within the Southern California Bight during spawning season (March - September) from 2016 onward. A range of lengths will be targeted to obtain juvenile through adult size classes. Staff will calculate the following reproductive parameters for white seabass: gonadal somatic indices (GSI), length and age at which 100% of fish have reached maturity, fecundity and the reproductive potential of adults.

An improved dataset for white seabass EFI (reproductive parameters) will allow CDFW to evaluate the effectiveness of current size limits. The collection of this EFI will contribute to stock assessments and FMPs and generate reliable spawning biomass estimates.

Recreational

  • Ocean Sport Fishing
    Provides links to current Ocean Sport Fishing Regulations, California Code and Regulations, Title 14, regulation changes, closures, and more.

Commercial

  • Commercial Landing Totals
    All commercially caught fish landed within the State must be accurately documented. The CDFW maintains basic catch records of amounts and values of the various marine resources taken by California's commercial fisheries.
  • Commercial Ocean Fishing
    Provides links to the current Commercial Fishing Digest, California Code of Regulations, Title 14, license information, and more.
  • Fish Business Information
    The CDFW License and Revenue Branch provides excellent service to our customers by issuing licenses, permits, stamps and tags consistent with statutory and regulatory requirements, collecting revenue, and providing information to support the use and enjoyment of California's diverse natural resources and insure that they are available for future generations.

White Seabass Activities

The CDFW conducts an annual review of the white seabass fishery as required by the White Seabass Fishery Management Plan. The Northern and Central California Finfish Research and Management Project assists in sampling the recreational and commercial fisheries in Monterey Bay as needed. Project staff also convene an annual meeting of white seabass fishery stakeholders and produce an annual report (A Summary of Information: White Seabass Fishery and Sampling Programs as related to the Annual Review of the White Seabass Fishery Management Plan) for the Fish and Game Commission.

  • Annual Reviews of White Seabass Fishery Management
    Each year the White Seabass Scientific and Constituent Advisory Panel meets to consider if current management measures are providing adequate protection for the white seabass resource. Annual reviews are conducted so that any changes in management, or to the White Seabass Fishery Management Plan, can be considered by the Commission in accordance with the requirements of the Marine Life Management Act. The Advisory Panel meets with CDFW each spring.
  • Nearshore and Bay Management Project (NBMP)
    NBMP staff coordinate the activities of the Ocean Resources Enhancement and Hatchery Program (OREHP) which is involved in the experimental culture and release of white seabass for fishery enhancement purposes.

Project Resources

  • Annual Status of the Fisheries Reports (2006)
    The Marine Life Management Act (MLMA) of 1998 mandated that California Department of Fish and Wildlife (CDFW) review at least one quarter of state-managed marine fisheries annually with focus on species that are the subject of a directed recreational or commercial fishery. The report contains a history of the fishery, status of biological knowledge, the status of the population, management considerations, and references to more white seabass information.
  • link opens in new windowWhite Seabass (PDF)
    Excerpt from Review of Selected California Fisheries for 2005: Coastal Pelagic Finfish, Market Squid, Dungeness Crab, Sea Urchin, Abalone, Kellet's Whelk, Groundfish, Highly Migratory, Species, Ocean Salmon, Nearshore Live Fish, Pacific Herring, and White Seabass, M. Connell, author. 2006 CalCOFI Report, Volume 47, pgs. 27-29
  • link opens in new windowWhite Seabass (PDF)
    Excerpt from Review of Selected California Fisheries for 2008: Coastal Pelagic Finfish, Market Squid, Ocean Salmon, Groundfish, California Spiny Lobster, Spot Prawn, White Seabass, Kelp Bass, Thresher Shark, Skates and Rays, Kellet's Whelk and Sea Cucumber, V. Taylor, author, 2009 CalCOFI Report, Volume 50, pgs. 27-30
  • link opens in new windowWhite Seabass Brochure (PDF)
    This brochure provides a summary of information about white seabass including fishing, identification, life history, and management.
  • White Seabass Fishery Management Plan
    Concern over the decline in white seabass landings and conflict between recreational and commercial fishermen over this resource from the mid- to late-1900s resulted in legislation requiring the development of the White Seabass Fishery Management Plan. The plan was developed in 1995 and adopted by the Fish and Game Commission in 1996. However, regulations to implement the plan were not adopted at that time. The CDFW revised the plan in accordance with the Marine Life Management Act and submitted it to the Commission, which adopted it on April 4, 2002.

A school of white seabass

A young angler standing on a boat with several white seabass on the deck

A commercial fisherman with many white seabass on the deck of his boat

Kelp Bass

Species Identification

The kelp bass (Paralabrax clathratus), also known as calico bass, is characterized by its similarity to a freshwater largemouth bass. Its third and fourth dorsal spines are of equal length, and are approximately twice the length of the second dorsal spine. The upper part of the head is brownish-olive with random yellow spots, and the upper back is mottled with characteristic white blotches on a brown background. The fins have a yellowish coloration. Breeding males have an orange-colored chin.

There are two rows of the characteristic rectangular white blotches on the back. The bass is easily differentiated from other members of the bass family by these white blotches. Sometimes these bass are confused with yellowtail rockfish or olive rockfish. Rockfish have spines on the operculum (cheek) which are not present on kelp bass.

Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Perciformes
Family: Serranidae
Genus: Paralabrax
Species: clathratus

Kelp Bass

Studies

The State Finfish Management Project was created in July 2006. In 2011 the Project was re-organized and the Southern California Fisheries Research and Management Project assumed all work for kelp bass and other basses. Bass project staff are based in Los Alamitos. The fishery data collected include length-at-age, catch per unit-of-effort, seasonal maturity, fishing gear effects on undersized fish, and relative species composition within habitats. These data are collected in order to manage fisheries with the best available information and ensure their long term resource sustainability for economic and recreational benefits.

Historical Length and Catch Data

Marine Recreational Fisheries Statistics Survey (MRFSS) and California Recreational Fisheries Survey (CRFS) kelp bass length and catch data from 2000 to 2008 were analyzed by project staff to determine trends in length and angler catch (or bag) frequencies. All data analyzed were obtained from anglers interviewed by MRFSS and CRFS field technicians. These data will be used to assist in future kelp bass population evaluations. Summaries of data are provided below.

Length Frequency Data

The total length (TL) data summarize the total number of kelp bass measured from interviewed anglers each year. The TL data were grouped into four length intervals: less than 12 inches (sub-legal), 12 to 12.99 inches, 13 to 17 inches, and greater than 17 inches to provide a better understanding of length distribution. Average percentages were calculated for the 9-year period and results indicated that almost 86% of all kelp bass measured were from the 12- to 17- inch TL interval.

2000-2008 Kelp Bass Length Frequency Data by Year
Year Number of Fish & Percentage Total Length of Kelp Bass (in inches)
<12 12 to 12.99 13 to 17 >17
2000 Number of Fish 34 234 704 120
Annual Percentage 3.11 21.43 64.47 10.99
2001 Number of Fish 41 227 514 55
Annual Percentage 4.90 27.12 61.41 6.57
2002 Number of Fish 83 503 896 133
Annual Percentage 5.14 31.15 55.48 8.24
2003 Number of Fish 91 814 1431 233
Annual Percentage 3.54 31.69 55.70 9.07
2004 Number of Fish 152 1071 3306 566
Annual Percentage 2.98 21.02 64.89 11.11
2005 Number of Fish 134 828 2473 589
Annual Percentage 3.33 20.58 61.46 14.64
2006 Number of Fish 146 1103 4214 878
Annual Percentage 2.30 17.39 66.46 13.85
2007 Number of Fish 107 722 2615 544
Annual Percentage 2.68 18.10 65.57 13.64
2008 Number of Fish 184 1045 2933 450
Annual Percentage 3.99 22.66 63.59 9.76
Combined 2000-2008 Total Number of Fish 972 6547 19086 3568
Average Percentage 3.55 23.46 62.11 10.87

Note: MRFSS and CRFS kelp bass length measurements were collected as fork length in millimeters. All fork lengths presented here were converted to total length in inches as California regulations are written in this manner.

Catch Frequency Data

The kelp bass catch frequency data summarize the number of fish caught (also called daily bag and possession) per individual interviewed angler from 2000 to 2008. The table below provides annual summaries of total fish caught, total number of anglers sampled, and the average number of fish per angler. Data summarized include all angler trips that targeted kelp bass, which means that bags over the legal 10-fish limit and bags with zero fish caught were included. The average annual catch of kelp bass per angler for the 9-year period was 0.8 fish. If bags with zero fish were eliminated from the summary, the average annual catch of kelp bass per angler for the 9-year period would be 2.1 fish.

2000-2008 Kelp Bass Average Angler Catch (or Bag) by Year
Year 2000 2001 2002 2003 2004 2005 2006 2007 2008 Combined
Number of Fish 1496 1077 1842 3394 9834 4547 6253 5075 4837 38355
Number of Anglers 1474 1269 2253 3669 8944 6393 7666 7907 7650 47225
Average Fish per Angler 1.01 0.85 0.82 0.93 1.10 0.71 0.82 0.64 0.63 0.81

Reproduction

Spawning Frequency

If a female has recently spawned, postovulatory follicles will be present in the ovaries. When we know what proportion of females have postovulatory follicles, we can estimate spawning frequency. In a previous study conducted 25 years ago over a brief portion of the spawning season, a small sample size indicated that female kelp bass spawn approximately every two and a half days. In 2013, we examined the current spawning frequency exhibited by kelp bass over the course of the entire spawning season.

Results coming soon!

Spawning Periodicity

Fish spawning is triggered by environmental cues. In marine environments, common cues include lunar and/or tidal flux. These cues are important for species to successfully reproduce and may indicate the best times for survival of fertilized eggs and larvae. Kelp bass may experience other environmental cues such as increased day length or increased temperature that drive them to form spawning aggregations, but there may be additional, closely related environmental cues throughout the spawning season that trigger spawning pulses. Understanding which cues trigger spawning in kelp bass is important for understanding how and why reproductive potential sometimes varies from year to year.

Reproductive hormones fluctuate with respect to environmental cues and may peak during spawning pulses. With support from the Reproductive Biology Lab run by Dr. Kelly Young at California State University Long Beach, we used enzyme immunoassays to measure the concentration of estradiol in the blood plasma collected from kelp bass over the course of the 2013 spawning season to estimate spawning periodicity.

We also looked at how hormone concentrations relate to fish size, gonad size and the presence or absence of post-ovulatory follicles produced by females following spawning events.

Results coming soon!

organic shapes
Example of a histological section of a bass ovary showing a post ovulatory follicle (POF) surrounded by oocytes in various stages of development (Photo: CDFW)

Batch Fecundity

Kelp bass are serial spawners, meaning they may spawn many times over the course of a spawning season. As in other serial spawners, kelp bass ovaries contain eggs at several different stages of development; however, only the hydrated eggs will be spawned.

Batch fecundity refers to the number of eggs released in one spawning event. By determining the batch fecundity for several individuals over a wide size range, we can develop a batch fecundity-size relationship which allows us to estimate the batch fecundity of females measured in the field. Batch fecundity will be an important parameter for estimating reproductive potential of kelp bass.

Staff counted the number of hydrated eggs in the ovaries to determine batch fecundity for individual fish.

Results coming soon!

Age and Growth

The age of many fish can be determined by analysis of their otoliths. Otoliths are hard structures located in the inner ear that grow as the fish grows by adding layers of calcium carbonate. The addition of layers is affected by seasonal changes in growth rate, so that calcium carbonate rings may form annually and can be counted similar to tree rings. By counting the rings on the otoliths we can estimate the age structure of kelp bass. In 2013 we collected 806 otoliths from kelp bass in the southern California bight and the data is currently being processed for publication.

While examining otoliths is a common ageing technique in fish, no one has ever validated that the ring pattern is annual across size classes in kelp bass. To examine this, we will keep kelp bass of several size classes in captivity for at least one year. Shortly upon capture we will inject a chemical marker called oxytetracyline (OTC) into the musculature that will be naturally incorporated into the otoliths. After a year, we will remove the otoliths and confirm the periodicity of the ring pattern.

Results coming soon!

Project Resources

  • Annual Status of the Fisheries Reports (2003)
    The Marine Life Management Act (MLMA) of 1998 mandated that California Department of Fish and Wildlife (CDFW) review at least one quarter of state-managed marine fisheries annually with focus on species that are the subject of a directed recreational or commercial fishery. The report contains a history of the fishery, status of biological knowledge, the status of the population, management considerations, and references to more kelp bass information.
  • Kelp Bass (PDF)
    Excerpt from Review of Selected California Fisheries for 2008: Coastal Pelagic Finfish, Market Squid, Ocean Salmon, Groundfish, California Spiny Lobster, Spot Prawn, White Seabass, Kelp Bass, Thresher Shark, Skates and Rays, Kellet's Whelk and Sea Cucumber, O. Horning, author, 2009 CalCOFI Report, Vol 50, pgs. 30-32.

organic shapes
Example of oocyte developmental stages in bass:
A – Hydrated
B, C, D – Vitellogenic
E – Cortical alveolar
F – Primary growth

 

Barred Sand Bass

Movement and Habitat Association

Background

Barred sand bass, Paralabrax nebulifer, are one of the most sought-after sport fishes in southern California. Since the 1960s, this species has ranked among the top ten sport fish caught by commercial passenger fishing vessels (CPFVs), or "party boats," in southern California, with annual catches averaging nearly one million fish over the last 20 years. For decades, CPFVs and private recreational boaters have targeted well-known spawning aggregation sites throughout southern California, including the Ventura Flats, Santa Monica Bay, Huntington Beach Flats, San Onofre, and San Diego. Approximately 71 percent of the annual barred sand bass catch is harvested by the CPFV fleet from June through August, during peak spawning season.

Records show that from 1961 to 2000 barred sand bass catches increased, followed by a dramatic decline in landings through 2008. These dramatic catch declines in recent years have caused concern among fisheries biologists and fishermen alike. A 2010-2011 fishery analysis on the basses (including barred sand bass) indicates that bass populations in the last decade have been negatively affected by cool oceanographic conditions and fishing. Answering scientific questions regarding barred sand bass spawning behavior, movements and spawning habitat requirements will be important for the management of this resource.

Barred sand bass catch location data was compiled by California Recreational Fisheries Survey samplers for private/rental boats from 2004-2008 in the southern California region. Samplers interview anglers at public launch facilities, ask questions about their fishing activities, examine their catch to determine the number and species of fish kept or discarded, weigh and measure the catch, and collect fishing location and depth information. The catch location data were mapped and analyzed and major "hotspot" catch locations (potential spawning grounds) were identified using a Geographic Information System. This analysis provides valuable information about where and when barred sand bass spawning aggregations may occur in southern California. In addition, areas fished around Huntington Beach were examined on a finer scale to examine any seasonal patterns of catch.

Spawning Movements

In the 1960s and 1990s, CDFW biologists tagged a total of 9,000 barred sand bass in southern California. The recapture information from these two time periods enabled us to document large-scale spawning-related movements of barred sand bass for the first time. Using this dataset we attempted to discover:

  • How long individual barred sand bass remain at spawning grounds during spawning season
  • How far fish migrate to spawn
  • Whether fish show fidelity to certain spawning locations

In addition to large-scale spawning movements, we were also interested in the short-term, fine-scale spawning movements of barred sand bass. To address this, project staff worked with California State University, Long Beach professor Dr. Chris Lowe and his master's student, Megan McKinzie. Project staff assisted with field research that uses state-of-the-art technology to actively track adult barred sand bass at Huntington Flats during the spawning season. Fish were surgically fitted with acoustic transmitters and then followed by boat using an underwater hydrophone. Several transmitters contained depth sensors which emitted a signal that allowed the researcher to determine both the horizontal and vertical movements of the fish every two seconds.

The results from this research allowed us to characterize fine-scale horizontal and vertical movement patterns of tagged barred sand bass during the spawning and non-spawning seasons, and to quantify activity space size (area and volume), habitat use and preference, and patterns of activity throughout a 24-hour period. Movement patterns believed to be indicative of spawning and/or courtship were determined through the comparison of spawning and non-spawning season individuals.

(1) With the fish immersed in a saltwater anesthetic bath, the transmitter is inserted through a small incision in the lower abdominal cavity. (2) Two to three sutures are used to close the incision. (3) Prior to release, the fish is measured and fitted with an external dart tag for easy identification upon recapture.
(1) With the fish immersed in a saltwater anesthetic bath, the transmitter is inserted through a small incision in the lower abdominal cavity.
(2) Two to three sutures are used to close the incision.
(3) Prior to release, the fish is measured and fitted with an external dart tag for easy identification upon recapture.

CDFW photos by E. Jarvis

Spawning Habitat

The timing and location of spawning aggregations are related to water temperature, lunar activity, and currents for some other aggregate spawners. However, depth and bottom habitat type are the only characteristics documented in historical descriptions for barred sand bass spawning aggregation sites. To understand whether barred sand bass spawning aggregation sites were unique, Fisheries Independent Assessment Project staff conducted field surveys in 2008 to determine the typical oceanographic (water temperature), seafloor habitat (type of substrate), and biological features (invertebrates living on and in the substrate) of areas where barred sand bass spawning aggregations occur and areas where they are absent.

Barred sand bass 'resting' at spawning grounds. CDFW photo, circa 1961.
Barred sand bass "resting" at spawning grounds. CDFW photo, circa 1961.

Findings to Date

"Hotspot" Analysis

During the summer months, five "hotspots" for barred sand bass catch were identified that are likely major spawning grounds for this species. The proportion of catch varied among these "hotspots" from 2004 to 2008 with Huntington Flats off Orange County and Imperial Beach ("I.B." Flats) on the U.S./Mexico border in San Diego County being the top catch locations. On a finer scale, natural reefs (Horseshoe Kelp and Palos Verdes Peninsula) and artificial structures (reefs, oil rigs, and breakwaters) were more important catch locations in the Huntington Beach Flats area outside of peak spawning season. This suggests that areas with higher relief or structure may serve as important habitat for barred sand bass before and after spawning activities.

Barred Sand Bass Catch Locations in the Summer Months 2004-2008
Map of the Southern California Bight showing the number of barred sand bass kept and released by private/rental boats from 2004-2008 by 1x1 mile fishing block from June - August. The percentages represent the proportion of barred sand bass caught by county and standardized by area (1x1 mile fishing block).

Spawning Movements

Tag and Recapture Data

The CDFW received 972 barred sand bass tag returns from tagging efforts conducted in the 1960s and 1990s (an 11 percent recapture rate). Based on recapture frequencies, it appears that barred sand bass individuals remain on spawning grounds (e.g., Huntington Beach Flats) for at least one month during peak spawning season. Spawning residency at Huntington Flats was estimated by the frequency of returns over time; most same-year returns (82%, n = 141) were recaptured within a 35-day period, with secondary peaks in returns at 28 and 56 days at liberty.

Barred Sand Bass Catch Locations in the Summer Months 2004-2008
Frequency of tag returns over time for fish tagged during peak spawning season (June through August) at Huntington Flats and recaptured there within the same year.

Following spawning season, some fish remain, while others move away. The average migration distance from spawning locations was about 15 miles, although it appears that not all individuals at spawning grounds migrate to the same locations after spawning season. Overall, the farthest recapture distance was approximately 57 miles. Annual patterns in the timing and occurrence of recaptures strongly suggest barred sand bass visit the same spawning grounds year after year.

Recapture matrix of barred sand bass tagged during peak spawning season (Jun-Aug) and recaptured in subsequent peak spawning seasons.
Recapture matrix of barred sand bass tagged during peak spawning season (Jun-Aug) and recaptured in subsequent peak spawning seasons.

Fine-Scale Movements

Three distinct patterns of behavior were identified and believed to be representative of non-spawning season behavior, spawning season resting behavior, and spawning/courtship related behavior. Non-spawning season fish remained more closely associated with reef habitats than sand habitat, used smaller activity spaces, and remained more closely associated with the substratum than fish tracked during the spawning season.

Fish tracked during the spawning season used significantly more area and volume, and preferred sand over available reef habitats than fish tracked during non-spawning season. Spawning season fish typically utilized more of the available water column; individuals made dives toward the seafloor throughout the day and remained close to the seafloor at night. During the day, they remained primarily within or just below the thermocline (~ 16 °C), but continually made directed dives towards the seafloor lasting 15 to 30 seconds, a behavior believed to be analogous to vertical spawning rushes demonstrated by other serranids. Fish tracked during spawning season also demonstrated movement patterns similar to non-spawning season fish and was believed to be resting behavior.

Box and whisker plots of day versus night activity space-area during spawning and non-spawning seasons.
Box and whisker plots of day versus night activity space-area during spawning and non-spawning seasons.

Box and whisker plots showing distance from bottom during day and night periods for both spawning and non-spawning fish.
Box and whisker plots showing distance from bottom during day and night periods for both spawning and non-spawning fish.

3-D graphical representation of barred sand bass activity space usage during: (a) the non-spawning season, (b) presumed spawning/courting behavior and (c) resting periods.
3-D graphical representation of barred sand bass activity space usage during: (a) the non-spawning season, (b) presumed spawning/courting behavior and (c) resting periods.

Spawning Habitat

Seafloor Habitat and Invertebrate Densities

Not surprisingly, our results indicated the Huntington Flats largely consists of a uniform, sandy substrate; however, our analysis of existing substrate maps also identified several previously unknown areas of hard substrate sparsely scattered over the study area. Exploratory scuba dives conducted by CDFW staff identified barred sand bass on these reefs (some natural, some artificial) during peak spawning season, but we never observed courtship or spawning behavior even though dives occurred during daylight hours when barred sand bass reportedly spawn. Although there is potential barred sand bass spawning over reefs, the reefs may actually serve as areas for reproductive staging, resting, refuge, and foraging during spawning season.

The distribution of observed CPFV activity on barred sand bass spawning aggregations did not appear related to the distribution and (or) relative abundances of larger bottom invertebrates and animals that dwell within bottom sediments/sand. Fishermen have long associated barred sand bass spawning aggregations with "clam beds"; however seafloor video footage taken during opportunistic events on the Flats did not reveal evidence of large clam beds in the area. Although we did not collect sand bass stomachs for stomach content analysis, as they become adults barred sand have been shown to shift their diet predominantly to fishes that live near the bottom and crabs. Therefore, although clams occurred frequently in our benthic survey of the Flats, barred sand bass probably form aggregations over sand flats for reasons other than the presence of clams or other soft bottom prey items.

Hard and soft substrate mapped within the Huntington Flats study area in southern California in 2008. Data source: California Seafloor Mapping Project. Some areas beyond state waters (3 nm) were not available. Circled numbers reference small patches of hard substrate within the study area. AR=artificial reef.
Hard and soft substrate mapped within the Huntington Flats study area in southern California in 2008. Some areas beyond state waters (3 nm) were not available. Circled numbers reference small patches of hard substrate within the study area. AR=artificial reef. Data source: California Seafloor Mapping Project.

Oceanographic Conditions at Huntington Flats

The development of a strong thermocline occurred during late July and early August and coincided with the highest, sustained catch of barred sand bass during peak spawning season. Thermocline temperatures measured within areas of presumed aggregation activity were significantly warmer than the average thermocline temperatures measured throughout the area during June, July, and August. In subsequent years, barred sand bass tracked during spawning season were associated with the thermocline during the daytime (see Fine-scale Movements above). Previous research on the optimal thermal habitat for barred sand bass egg and larval development suggests warmer thermocline temperatures may increase larval fitness.

Daily catches of barred sand bass by the CPFV fleet were positively associated with fishing effort and tidal flux, and negatively associated with chlorophyll-a concentrations. These factors explained 72 percent of the variability in barred sand bass catch over the peak spawning season. Periods of high tidal flux occurred during both new and full moon phases; thus, the observed peaks in barred sand bass catch may represent a reproductive behavioral response to tidal amplitudes more so than moon phase. Sea surface currents were generally low during peak barred sand bass catches; however, Huntington Flats experienced large tidal fluxes of several feet.

The negative relationship between barred sand bass CPFV catches and chlorophyll-a concentrations is less clear. Chlorophyll-a concentrations are typically used as a proxy for phytoplankton abundance and tend to be inversely related to the ability of light to penetrate water in this area. A negative relationship with chlorophyll-a may reflect a preference of barred sand bass aggregations for increased water clarity, or it may reflect avoidance of forage fishes that eat plankton and zooplankton egg predators.

Comparison of average thermocline temperatures on the Huntington Flats in June, July, and August, and during sampling events located within barred sand bass aggregation fishing activity, 2008. Error bars represent 95% confidence intervals, the asterisk denotes a statistical difference among means.
Comparison of average thermocline temperatures on the Huntington Flats in June, July, and August, and during sampling events located within barred sand bass aggregation fishing activity, 2008. Error bars represent 95% confidence intervals, the asterisk denotes a statistical difference among means.

Monitoring

Diver and Video Surveys

Fishery-independent datasets provide critical information to the management of Barred Sand Bass and there is a lack of fishery-independent data on their abundance in southern California. Although some historical datasets exist, such as powerplant monitoring records of fish impingement, these have recently been phased out. Many entities run surveys of fish abundance on the slope of local rocky reefs, however Barred Sand Bass are more common along the ecotone (reef-sand interface) of artificial reefs. Because of this, SCFRMP staff have initiated a long-term monitoring study to create a fishery independent index of abundance for Barred Sand Bass. While underwater visual census (UVC) has been the most common non-extractive technique used in reef fish surveys, baited remote underwater videos (BRUVs) also show promise for surveying carnivorous species in deep, low visibility environments.

During June – October 2017 Department staff compared UVC and BRUV survey methods for quantifying the abundance of fishes at the ecotone of inshore natural and artificial reefs in southern California. Six reefs at the Los Angeles Harbor Breakwater and Palos Verdes Peninsula were sampled on a monthly basis. Results from this initial sampling will help characterize the best locations, season and substrate to conduct annual surveys, as well as the best survey method, or combination of methods to be used in the monitoring study design. In the future, survey data collected on annual basis will contribute an important fishery-independent measure of abundance to management.

Results from 2017 surveys are currently being analyzed.

Age Structure and Validation

The age of most finfish can be determined by analysis of their otoliths. Otoliths are hard structures located in the inner ear that grow as the fish grows by adding layers of calcium carbonate. The addition of layers is affected by seasonal changes in growth rate, so that calcium carbonate rings may form annually and can be counted similar to tree rings. We collected otoliths from 352 barred sand bass at Huntington Flats in 2011. By counting the rings on the otoliths we can estimate the age structure of barred sand bass at the Huntington Flats spawning aggregation in 2011. While this is a common ageing technique in fish, no one has ever validated that the ring pattern is annual across size classes in barred sand bass. To examine this, we will keep barred sand bass of several size classes in captivity for at least one year. Shortly upon capture we will inject a chemical marker called oxytetracyline (OTC) into the musculature that will be naturally incorporated into the otoliths. After a year, we will remove the otoliths and confirm the periodicity of the ring pattern.

We are currently processing otoliths. Stay tuned!

BRUV Frame Diagram
Diagram of the Baited Remote Underwater Video (BRUV) platform used in this study.

Cross-section of a sagittal otolith taken from a barred sand bass collected in the 1990s. The otolith was aged to 17 years. CDFW file photo.
Cross-section of a sagittal otolith taken from a barred sand bass collected in the 1990s. The otolith was aged to 17 years. CDFW file photo.