REFEREPJCB COPY 

Not Remove from the Library 

U. S. Fish and Wildlife Service 

~iological Report 82 (11- Wetlands Research Center TR EL.82.4 

March 1985 700 Cajun Dome Boulevard . - - 

Lafoyette, Louisiana 70506 

Species Profiles: Life Histories and 

Environmental Requirements of Coastal Fishes 

and Invertebrates (Pacific Southwest) 

BLACK, GREEN, AND RED ABALONES 

Fish and Wildlife Service 

Coastal Ecology Group 

Waterways Experiment Station 

U.S. Department of the Interior U.S. Army Corps of Engineers 
This is one of the first reports to be published in the new "Biological 

Report" series. This technical report series, published by the Research 

and Clevelopment branch of the U.S. Fish and Wildlife Service, replaces 

the "FWS/OBS1' series pub1 ished from 1976 to September 1984. The Biological Report series is designed for the rapid publication of reports with 

an application orientation, and it continues the focus of the FWS/OBS 

series on resource management issues and fish and wildlife needs. 
Biological Report 82(11. 32) 

TR EL-82-4 

March 1985 

Species Prof i 1 es: Life Hi stories and Envi ronmental Requirements 

of Coastal Fishes and Invertebrates (Pacific Southwest) 

BLACK, GREEN, AND RED ABALONES 

Jerald S. Ault 

Cooperative Institute for Marine and Atmospheric Studies 

4600 Rickenbacker Causeway 

Miami , FL 33149 

Project Manager 

Larry Shanks 

Project Officer 

John Parsons 

National Coastal Ecosystems Team 

U.S. Fish and Wildlife Service 

1010 Gause Boulevard 

Slidell, LA 70458 

Performed for 

Coastal Ecology Group 

Waterways Experiment Station 

U. S. Army Corps of Engineers 

Vicksburg, MS 39180 

and 

National Coastal Ecosystems Team 

Division of Biological Services 

Research and Development 

Fish and Wildlife Service 

U.S. Department of the Interior 

Washington, DC 20240 
This series should be referenced as follows: 

U.S. Fish and Wildlife Service. 1983-19 . Species profiles: life histories 

and environmental requirements of coastal fishes and invertebrates. U. S. Fish 

Wildl. Serv. Biol. Rep. 82(11). U. S. Army Corps of Engineers, TR EL-82-4. 

This profile should be cited as follows: 

Aul t, Jerald S. 1985. Species profiles: 1 ife histories and environmental 

requirements of coastal fishes and invertebrates (Pacific Southwest)--black, 

green, and red abalones. U.S. Fish Wildl. Serv. Biol. Rep. 82(11.32) U.S. 

Army Corps of Engineers, TR EL-82-4. 19 PP. 
PREFACE 

This species profile is one of a series on coastal aquatic organisms, 

principally fish, of sport, commerci a1 , or ecol og ical importance. The profil es 

are designed to provide coastal managers, engineers, and biologists with a brief 

comprehensive sketch of the biological characteristics and environmental requirements of the species and to describe how populations of the species may be 

evected to react to environmental changes caused by coastal devel opment. Each 

profile has sections on taxonomy, 1 ife history, ecological role, environmental 

requirements, and economic importance, if appl icabl e. A three-ring binder is 

used for this series so that new profiles can be added as they are prepared. This 

project is jointly planned and financed by the U.S. Army Corps of Engineers and 

the U.S. Fish and Wildlife Service. 

Suggestions or questions regarding this report should be directed to one 

of the following addresses. 

Information Transfer Special is t 

National Coastal Ecosys tems Team 

U.S. Fish and Wild1 ife Service 

NASA-Sl idel 1 Computer Compl ex 

1010 Gause Boulevard 

Sl idel 1 , LA 70458 

U.S. Army Engineer Waterways Experiment Station 

Attention: WESER-C 

Post Office Box 631 

Vicksburg, MS 39180 
CONVERSION TABLE 

Metric to U.S. Customary 

Mu1 tiply !ti To Obtain 

mil 1 imeters (mn) 

centimeters (an) 

meters (m) 

ki 1 meters ( km) 

square meters (mL) 10.76 

square ki 1 meters (km2) 0.3861 

hectares (ha) 2.4 7 1 

inches 

inches 

feet 

mil es 

square feet 

square miles 

acres 

liters (1) 

cubic meters (m3) 

cubic meters 

0.2642 gal 1 ons 

35.31 cubic feet 

0.0008110 acre-feet 

mil 1 igrams [mg) 0.00003527 ounces 

grams (g) 0.03527 ounces 

kil ograms (kg) 2.205 pounds 

metric tons (t) 2205.0 pounds 

metric tons 1.102 short tons 

ki 1 ocal ories ( kcal ) 3.968 British thermal units 

Cel sius degrees 1.8("~) + 32 Fahrenheit degrees 

U.S. Customary to Metric 

inches 2 5.40 

inches 2.54 

feet (f t) 0.3048 

fa thoms 1.829 

miles (mi) 1.609 

nautical miles (mi) 1.852 

square feet (ft2) 

acres 2 

square miles (mi ) 

gal 1 ons (gal ) 3.785 

cubic feet (ft3) 0.02831 

acre- feet 1233.0 

ounces (oz) 28.35 

pounds (Ib) 0.4536 

short tons (ton) 0.9072 

British thermal units (Btu) 0.2520 

mil 1 imeters 

centimeters 

meters 

meters 

kil ometers 

ki 1 ometers 

square meters 

hectares 

square kilometers 

liters 

cubic meters 

cubic meters 

grams 

ki 1 og rams 

metric tons 

ki 1 ocal ori es 

Fahrenheit degrees 0.5556("F - 32) Celsius degrees 
CONTENTS 

Page 

PREFACE .............................................................. iii 

CONVERSION TABLE ....................................................... iv 

ACKNOWLEDGMENTS ....................................................... vi 

NOMENCLATURE AND TAXONOMY .............................................. 1 

REASONS FOR INCLUSION IN THE SERIES .................................... 1 

GEOGRAPHIC RANGE ...................................................... 1 

MORPHOLOGY AND IDENTIFICATION AIDS ..................................... 1 

Black Abalone ....................................................... 1 

Green Abalone ........................................................ 4 

Red Abalone .......................................................... 4 

LIFE HISTORY ..................................................... 4 

Spawning and Maturation .............................................. 4 

Black abalone ...................................................... 5 

Green abalone ...................................................... 5 

Red abalone ........................................................ 5 

Larval Development ................................................. 5 

Postlarvae and Juveniles ............................................. 6 

Habitat .............................................................. 6 

GROWTH CHARACTERISTICS ................................................. 7 

THE FISHERY ........................................................... 8 

Commercial Fishery ................................................... 8 

Sport Fishery ........................................................ 10 

Resource Status ...................................................... 10 

ECOLOGICAL ROLE ........................................................ 11 

Food and Feeding Habits .............................................. 11 

Black abalone ...................................................... 13 

Green abalone ..................................................... 13 

Red abalone ....................................................... 13 

Competition and Predation ........................................... 14 

ENVIRONMENTAL REQUIREMENTS ............................................. 15 

Temperature .......................................................... 15 

Depth ................................................................ 15 

Other Environmental Requirements ..................................... 16 

LITERATURE CITED ....................................................... 17 
ACKNOWLEDGMENTS 

I am grateful for the reviews by John D. DeMartini, Telonicher Marine 

Laboratory, Humboldt State University; David L. Leighton, World Research, Inc.; 

and Earle E. Ebert and Steven A. Schultz, California Department of Fish and Game. 

Thomas J. Hassler (Cal ifornia Cooperative Fishery Research Unit) kindly acted as 

the liaison with the National Coastal Ecosystems Team and greatly facilitated the 

completion of this report. 
BLACK, GREEN, AND RED ABALONES 

Scientific name . . . . . . Haliotis 

cracherodii Leach 

Preferred comon name . Black abalone 

Scientific name . . . . . . Haliotis 

fulgens Philippi 

Preferred common name . Green abalone 

Scientificname.. . . . Haliotis 

rufescens Swainson 

Preferred common name . . Red abalone 

Class . . . . . . . . . . Gastropoda 

Order . . . . . . . Archaeogastropoda 

Family . . . . . . . . . . Haliotidae 

REASONS FOR INCLUSION IN THE SERIES 

All abalones belong to the genus 

Haliotis sensu latu, family Haliotidae. The 75 species known worldwide 

(Booloot ian et, al. 1962) are anatomically similar and all are adapted for 

attachment to hard substrates. Seven 

species are widely distributed along 

the coast of California (Cox 1962; 

Mottet 19781, of which several are 

important in the comercial and sport 

fisheries of the Pacific Southwest. 

(See Figure 1 for shell characteristics.) 

GEOGRAPHIC RANGE: 

Black abalone ranges along the 

Pacific coast from San Francisco Bay, 

Cal ifornia, to Bahia Santa Maria, Baja 

California Sur, Mexico, including the 

Coronado, Guadalupe, and all the 

Channel Islands. Generally, it is 

comon to the south and rare to the 

north of Point Lobos (Figure 2). 

The green abalone ranges from Point 

Concept ion to Bahia Magdalena, Baja 

California Sur, Mexico (Leighton et 

al. 19811, including the California 

localities of San Clemente, Santa 

Catal ina, Santa Barbara, Anacapa, and 

Coronado Is1 ands. 

The red abalone ranges from Sunset 

Bay, Oregon, to Bahia San Bartolome, 

Baja Cal ifornia (29 N Lat. 1, including 

the Farallon and Channel Islands (Cox 

1962; Leighton 1968). It is rare 

north of She1 ter Cove, California. 

MORPHOLOGY AND ICIENTIF ICATION AIDS 

Bl ack Abal one 

The shell of the black abalone is 

comparatively deep and oval, its 

average shell length is about 115 mm 

(maximum 215 mm). The shell exterior 

is dark blue, black, or greenish black, 

usually smooth, and supports few or no 

encrusting organisms. Its round respiratory apertures (pores), which are 

flush with the shell surface, are about 

3 mm in diameter. Usually five to nine 

pores are open at any one t ime, but in 

specimens from Baja Cal ifornia and 

Guadalupe Island, 11 to 14 pores may 

be open. The interior shell pigmentation is cream to silver pearl with 

pink and green iridescence. A columellar muscle scar is lacking. The 

outer edge of the 'she1 1 protrudes over 

a nacreous surface forming a narrow, 

dark blue-black rim. 
I \Respiratory Apertures. 

Figure 1. Shells of the black, green, and red abalones. Length measurement 

typical shell is shown in lower left. 
, 

\ 

\ 

\ 

\ 

CALI FORNIA \ 

\ 

\ 

LOS ANGELES 

MILES 

0 - 50 100 150 

0 50 100 150 200 

KILOMETERS 

. -- -_ 

Figure 2. Coastal distribution of the black, green, and red abalones 

in California. 
The epipodium (dorsal rim of the the particular brown algae being confoot) is smooth and black. Its upper sumed (Leighton 1961; Olsen 1968a,b). 

edge is scalloped and bears short, The shell is often overgrown by 

slender tentacles that somet imes sess i 1e organisms that are common to 

protrude sl ightly beyond the edge of the area. The shell interior is smooth 

the shell. and brilliantly iridescent with deep 

green and blue shades; green and black 

spots may also be present. The interGreen Abalone 

The shell of the green abalone is 

oval; its average length is 175mm 

(maximum 250 mm). The shell exterior 

is olive-green to red-brown and regular in form and sculpture with fine 

spiral ribs. The shell surface is 

often overgrown with encrusting invertebrates and algae. The circular 

respiratory apertures are about 5 mm 

in diameter and sl ightly raised; usually five to seven are open. The 

shell interior is smooth and strongly 

iridescent, having deep green, blue, 

and lavender shades and some black 

spots. A prominent, central, 

columellar muscle scar is present; the 

shell is considered to be the most 

beautiful of all abalones. 

The ep ipodium of the green abalone is olive green with patches of 

brown. It is scalloped along the edge 

and small tuberculations give it a 

rough, frilled surface. Epipodial 

tentacles are grayish green, short, 

and thick, and project slightly. 

Red Abalone 

The red abalone is the largest of 

the abalones. The average shell 

length is about 220 mm (maximum 292 

mm). Usually, three to four respiratory pores are open along the sinistral margin of the shell at agiven 

time. The outline of the pores are 

oval and typical ly sl ightly elevated. 

The shell exterior is commonly lumpy, 

irregular, and red. The redness is 

conferred by red algae in the diet. 

The ostracal shell layer is typically 

dull brick red (Cox 1962). If red 

abalone feed on brown rather than red 

algae, the shell colors range from 

white to cream to green, depending on 

ior b e a r s - a large, ' prominent, central 

columellar muscle scar with rough texture. The outer lip of the shell 

extends over an inner nacreous surface 

forming a rim (red if the abalone has 

been feeding on red algae). 

The epipodium and lateral portion 

of the foot are smooth and usually 

black; however, the epipodium of a 

second prominent phenotype has alternat ing dark and 1 ight vertical bars. 

The edge of the epipodium is scalloped; black epipodial tentacles can 

be extended beyond the edge of the 

shell. In some individuals, the upper 

edge of the epipodium is white. The 

epipodium protrudes beyond the edge of 

the shell when the animal is either 

relaxed or feeding. 

LIFE HISTORY 

Spawning and Maturation 

Abalones 1 ack evident sexual 

dimorphism and are dioecious, broadcast spawners. The sex of mature 

specimens can be determined by gonadal 

color (Cox 1962; Leighton and Boolootian 1963; Mottet 1978). Thetestis 

is usually white, yellow-cream, or 

beige; the ovarian tissue is dark 

green in black and red abalones and 

their larvae are conspicuously green. 

The green abalone has brownish-green 

ovarian tissue and produces brown 

eggs. Immature gonads are brown or 

brownish-gray -- the color of the 

hepatic tissue. 

Gonadal histology has been 

described for the black abalone by 

Boolootian et al. (1962); for the 

green abalone by Sevilla et al. (1965) 

and Tutschulte (1976); and for the red 
abalone by Young and DeMart in i (1970). 

All three species are histologically 

similar and there is no evidence of 

sex reversal. According to Le ighton 

(1968) and Ault (19821, maturation of 

the gonads depends largely on the 

quality and quantity of available 

food, and to a lesser extent on 

temperature (within certain 1 imits). 

Seasonal changes in the avai 1 abi 1 i ty 

of food may determine the period of 

gamete product ion (Booloot ian et a1 . 1962). Low food intake, combined with 

seasonally low ambient water temperatures, may cause suboptimal gamete 

development (Young and DeMartini 1970; 

Giorgi and DeMartini 1977; Ault 1982). 

All three species of abalones 

d e s c r i b e d h e r e spawn primar i ly in 

spring and early summer. 

Black abalone. A1 though black 

abalone usually spawn in late spring 

and early summer in both central 

California (Boolootian et al. 1962) 

and southern California (Leighton and 

Boolootian 19631, a minor second pulse 

of spawning in early fa1 1 was reported 

in central California by Webber and 

Giese (1969). Most black abalone 

longer than 44 mm were sexually mature 

near Point Dume in southern California 

(Leighton and Booloot ian 1963). Gametogenesis is begun imned iately after 

spawning is completed (Webber and 

Giese 1969). 

Green abalone. Green abalone 

spawn from April through October in 

Cal ifornia coastal waters (Leighton 

1979; Leighton et al. 1981; Tutschulte 

and Connell 1981) and as far south as 

Ensenada and Cedros Island in Mexico 

(Sevilla et al. 1965; Cota 1970). 

Green abalone off Santa Catal ina 

Island may spawn twice a year (Tutschulte 1976). They mature sexually at 

5 to 7 years of age at lengths of 80 

to 120 mm (Tutschulte and Connell 

1981). In 1 aboratory experiments, 

green abalone became sexual ly mature 

and produced viable larvae as early as 

1.5 years and lengths of 40 to 50 mm 

(Leighton et al. 1981). In California 

coastal waters, individual green abalone may produce from 100,000 to 6 

million eggs per spawn (Tutschulte 

1976). 

Red abalone. Peak spawning of 

red abalone in the northern port ion of 

their range coincides with spring 

benthic brown algal blooms. In 

northern Cal iforn ia, the spawn ing 

season extends from April through July 

(Giorgi and DeMartini 1977; Ault 

1982). In southern California, they 

may spawn twice annually (Price 1974). 

Abalone living in the same environments have relatively uniform and 

similar gonadal development. Most red 

abalone in northern Cal iforn ia become 

sexually mature when shell length is 

about 100 mm (Giorgi and DeMartini 

1977). Abalone spawning for the first 

time may produce only a few thousand 

eggs, but older females may yield up 

to 6 million eggs (Giorgi and DeMartini 1977; Ault 1982). Red abalone 

reared in the laboratory became sexually mature and yielded viable larvae 

when about 40 mm long. Under optimum 

laboratory conditions, the fecundity 

of individual abalone can be doubled 

(Aul t 1982). Gametogenesis of coastal 

red abalone is begun immediately after 

spawning and may he completed within 4 

months (Ault 1982). Female red 

abalone first spawn in their third or 

fourth year of 1 ife and may continue 

to spawn for as long as 10 years. 

Necrosis of ova is suspected in geriatric females (Young and DeMartini 

1970; Giorgi and DeMartini 1977). 

Insufficient nutrition inhibits egg 

production and in extreme cases the 

eggs may be resorbed (Giorgi and 

DeMartini 1977). 

Larval Develo~ment 

Larval development of the abalones is well-documented (Leighton 

1974). Because the specific gravity 

of spawned eggs is greater than that 

of sea water, the eggs sink to the 

bottom. Upon fertilization, a membrane forms and 1 arval devel opment 

begins. The rate of embryonic development depends on temperature. Trocho- 
phore larvae hatch in 10 to 72 hours 

when the eggs are reared at water 

temperatures of 12 to 20 OC. Larvae 

are 1 eci thotrophic. Trochophores and 

veligers are most abundant near the 

surface of the water. 

Pigmentation of velar and visceral portions of the larvae may 

provide distinctive features for 

recognition of some species. Pigments 

derived from parental yolk appear to 

be retained by trochophore and v e l i g e r 

larvae of Haliotis (Leighton 1972). 

In the laboratory, veligers settle on 

the substrate when they are 5 to 14 

days old. Settl ing of postlarvae on 

coral 1 ine red algae can be induced by 

substances released in the water by 

the algae (Morse et al. 1979). 

Metamorphosis into juveniles requires 

individual contact with red algae 

(Morse et al. 1980), yet there is some 

evidence that settling is a random 

phenomenon. Settlement (the crawling 

stage) marks the end of larval life. 

Postlarvae and Juveniles 

Postlarvae are the settled young 

up to 10 mm long. They are characterized by the loss of the velar cilia 

and operculum, and the pronounced 

development of the foot and shell 

(Leighton 1974; Mottet 1978). After 2 

weeks, the postlarvae leave the 

coral1 ine alga on which they have 

settled and attach to rocks, especially in crevices (Cox 1962). The 

postlarvae have a well-developed 

radula (rasping tooth structure) for 

feeding on bacteria and diatoms that 

grow as a film on the substrate. Once 

they have started to feed, they begin 

to deposit the peristomal shell around 

the lip of the larval shell aperture. 

The shell is depressed and grows in 

the form of an equiangular spiral. 

New shell material is deposited to a 

greater extent on the right side of 

the aperture, producing a shell with a 

right-handed whorl. The spiral 

becomes flattened and the shell 

becomes ear-shaped (Haliotis = sea 

ear), a form well suited for clinging. 

Sensory tentacles have two 

ciliary lobes that create water currents over the ctenidia and epipodial 

tentacles, which function as chemosensory and tact i le-sensory structures. When postlarvae are 1 to 3 

months old and the shell is about 2 mm 

long, the first respiratory pore forms 

(Cox 1962) as the mantle separates 

along the sinistral margin of the 

shell opening and creates a notch 

(Leighton 1972 1. As growth proceeds, 

old pores are closed and new ones are 

formed one at a time along the growing 

margin of the she1 1. When the abalone 

is about 10 mm long -- now a juvenile 

-- it begins feeding largely on 

macroalgae, and to a much lesser 

extent on microflora (Cox 1962; 

Leighton and Booloot ian 1963; Mottet 

1978). Abalones are seldom seen in 

the open until they are 75 to 100 mm 

long (Cox 1962). 

Habitat 

Postlarvae, juveniles, and adults 

require hard substrate for attachment. 

The type and extent of rocky bottom 

materials 1 argely determine abalone 

abundance. Opt imum habitat consists 

of various combinations of ledges, 

cutbacks, depressions in stones, 

boulder piles, and other hard surfaces 

where food is abundant. Different 

microhabi tats are necessary for the 

growth and survival of abalones of 

different sizes and ages, as are an 

abundance of particular algae species 

for food. 

Black abalone live primarily in 

the rocky, mid-intertidal zone. Specimens larger than 90 mm tend to be 

sedentary and 1 ive under and on the 

sides of large rocks and in crevices. 

Smaller (c 90 mm) black abalone live 

primarily under boulders and in crevices. They move about more than the 

larger animals, presumably in search 

of food. The intertidal distribution 

of the species predisposes it to less 

predation from marine predators but to 

more predation from terrestrial predators (Morris et al. 1980). 
Green abalone are most abundant 

along rock headlands from the low 

intertidal zone to a subt idal depth of 

about 15 m. Headlands are exposed to 

high wave and current turbulence and 

abalones there are concentrated in 

crevices. The lower depth limits of 

abalones are governed by the severity 

of the wave action, by the availability of drifting red algae for food 

(Tutschulte 1976), and suitable water 

temperatures (Leighton 1974; Leighton 

et al. 1981). Juveniles also are 

abundant in areas where adults are 

abundant, especially in waters with 

strong currents and in crevices where 

coral 1 ine algae thrive. Postlarvae 

settle gregariously among adults 

(Tutschulte 1976; Morse et al. 1980). 

Most of the older juveniles and adult 

green abalone move frequently in 

search of food and protection 

(Tutschul te 1976). 

In northern Cal iforn ia, red abalone 1 ive in the lower intertidal 

zone, to a depth of about 6 m (J.D. 

DeMart in i pers. comm. 1. In southern 

Cal iforn ia they 1 ive subt idal ly out to 

depths of 40 m (Leighton 1968) but in 

northern Cal i f o r n i a abalones 1 onger 

than 75 mm live in crevices, under 

1 arge boulders, and on exposed bedrock 

where sea otters (Enhydra lutris) 

are scarce. Small er r-1 onee 

cryptic, at least diurnally. Red 

abalone up to 20 mm long commonly live 

under clean boulders with veneers of 

inarticulate coral 1 ine algae. Red 

abalone up to 80 mm long commonly live 

in crevices. The seams, cutbacks and 

ledges in rock faces where algae are 

abundant provide opt imal habitat for 

red abalone (J.D. DeMartini, Humboldt 

State University, California, pers. 

corn. 1. Red abalone seek locat ions 

where food is abundant and relatively 

easy to capture. The largest specimens tend to live in the choice locations (J.D. DeMartini, pers. comm.). 

Some abalone are re1 at ively inactive 

and do not forage unless they are 

unable to catch sufficient drift 

algae; they then forage mostly among 

kelp stands. 

GROWTH CHARACTERISTICS 

The growth rates of the three 

abalone species are re1 at ively uniform 

during their first few years (Leighton 

1974). The length of most abalone 

is 1 to 3 mm at the end of 3 months, 

about 20 mm at the end of the first 

year of 1 ife, and 75 to 100 mm by the 

end of the third to fourth year. 

Growth in girth and weight increase as 

length increases. Black abalone are 

rarely longer than 175 mm, and the 

maximum length for red abalone is 

about 290 mm. 

In southern California the average annual growth rate of the black 

abalone is about 20 mm over the first 

4 to 5 years of life (Leighton and 

Booloot ian 1963). In 1 aboratory 

experiments, green abalone were as 

long as 30 mm by the end of their 

first year of life (Leighton et al. 

1981). Tagged juvenile red abalone 

grew up to 48 mm in 1 year in central 

Cal ifornia (Cox 1962). 

Growth rates of abalones 

fluctuate with the seasonal abundance 

of kelps (Cox 1962; Leighton and Boolootian 1963). Growth is rapid during 

the summer, when brown macroalgae are 

most abundant. Differences in growth 

rates also may reflect the different ial nutrient qua1 ity of the available 

algae (Leighton 1972). In winter 

along the north coast of California, 

abalones may lose weight because of 

the paucity of brown algae for food. 

In northern California, about 80% of 

the annual growth of red abalone is 

during peak algal production in summer 

and fall (J.D. DeMartini, pers. comm.). 

According to Hansen (19701, the 

rate of shell growth slows or stops 

duriqg periods of accelerated gonadal 

growth, but more recent studies on red 

abalone in the laboratory indicate 

that shell growth and gonadal 

maturation may be simultaneous (Aul t 

1982). Gonadal development is fastest 

when the diet consists of giant kelp 

(Leighton 1968) or bull kelp (Ahlt 

1982). 

7 
Only a small percentage of 

abalones grow fast. Under optimal 

conditions in a laboratory culture, 

some juvenile red and green abalone 

grow as much as 50 mm in one year 

(Leighton et al. 1981; J. McMullen, 

Port Huememe, Cal ifornia, pers. 

comm. ) ; however, the average is near 

25 mm in the sea. 

THE FISHERY 

For comparison, the commercial 

catch data for abalone are compiled 

separately for southern California 

(Mexican border to Point Conception, 

Santa Barbara County, including the 

Channel Islands); central Cal ifornia 

(from Point Conception to San 

Francisco, including the Farallon 

Islands); and northern California 

(north of San Francisco to the Oregon 

border). 

Commercial Fishery 

Annual commercial landings of 

abalones have decl ined from 4.6 mi 1- 

lion pounds in 1966 to a low of 1 

million pounds in 1979 (Table 1). The 

foot meat of the abalones is a highly 

prized delicacy, noted for its rich 

flavor. Commercial processing commonly involves separation of the body 

from the shell; the viscera and dark 

portions of the epipodium are trimmed, 

and the remaining 1 ight meat is sl iced 

and pounded into steaks. The dorsum 

of the shells is sometimes cleaned 

with a strong acid; and the whole 

shell is then used as an ornament, or 

broken into smaller sections and 

pol ished for jewelry. Dwindling 

supplies have given this prized 

mollusk the distinction of being 

the highest priced domestically produced seafood in the United States. 

Historically, most of the commercial 

catch consisted of red abalone taken 

from central Cal iforni a coastal waters 

between Cape San Martin (Monterey 

County) and Avila (San Luis Obispo 

County) ; however, commerci a1 1 and ings 

of red abalone in central Cal ifornia 

Table 1. Commercial abalone landi nqs 

and ex-vgssel value in cal i fornia, 

1965-.I982 . 

Thousandsb Thousands 

Year of pounds of dollars 

'1ncl udes landings of black, green, 

red, pink, white, threaded, pinto, 

and flat abalones. (No data for 

1980). 

b~rom California Marine Annual Fish 

Landings. Bulletins of the Cali fornia Department of Fish and Game. 

'~rel iminary data. 

have declined partly because of the 

expansion of the range of the highly 

predatory sea otter into old establ ished abalone grounds. The other 

abalones e., pink, black, green, 

and white), taken primarily from 

southern Cal ifornia, now make up twothirds to three-fourths of the state 

abalone catch (Table 2). Commercial 

fishing for abalones is banned north 

of San Franc i sco. 

The commercial fishery in 

southern California is regulated by a 

split season (closures during February 

and August) and by size 1 imits. 

Fishing is regulated by limited entry. 

Comerc ial divers are restricted by 

types of gear, diving depth, and area 
Table 2. Annual commercial landings (pounds) of black, green, and red 

abalones at major ports of entry from 1972 to 1982a. (No data for 1980). 

Central Southern 

California California 

San Santa Los San 

Year Species Francisco Monterey Barbara Angeles Diego Total 

Bl ack 

Green 

Red 

Black 

Green 

Red 

Black 

Green 

Red 

Black 

Green 

Red 

Black 

Green 

Red 

Black 

Green 

Red 

Black 

Green 

Red 

Black 

Green 

Red 

Black 

Green 

Re d 

Black 

Green 

Re d 

'~rom Cal ifornia Marine Annual Fish Landings, Bulletins of the California 

Department of Fish and Game. 

b Prel irninary data. 
boundaries. Commercial divers use the 

"hookah" system, which consists of a 

compressor and a surge tank with 300 

to 500 feet of hose connected to a 

full face mask or the second stage of 

a scuba regulator. This system enables 

more than one diver to operate from a 

vessel and provides a more thorough 

inspection of crevices. Since the 

early 1950's the commercial diving 

fleet has increased from 75 vessels to 

about 210, an increase of nearly 180%. 

Although divers now use more efficient 

gear, they harvest only 50% of the 

amount that was consistently landed by 

the smaller fleet in the 1950's (Burge 

et al. 1975). 

Sport Fishery 

Since 1965, there has been a 400% 

increase in the number of recreational 

scuij;. divers who search for abalones 

in southern California, and a 250% 

increase in catch. The number of 

party boats designed for the use of 

scuba divers has also increased. These 

vessels now have sufficient range to 

take divers to all offshore islands in 

southern Cal iforn i a. In central and 

northern California, there has been a 

more than 400% increase in shorepickers and divers, and a doubling of 

the sport catch from Marin, Sonoma, 

and Mendocino Counties between 1965 and 

1980. In central California the scuba 

season lasts 10 months. In northern 

California the catch is restricted to 

"free" divers (using mask and snorkel 

and beach combers over a spl it 7-month 

season. 

The dai ly possess ion 1 imi t in 

Cal ifornia is four abalones of any 

combinatim of species. Eight 

abalones are a1 lowed in possession by 

sport-divers d e c l a r i n g a mu1 t i-day 

trip to offshore waters. Accessible 

red abalone populations in northern 

California are now at their optimum 

yield for sport purposes (Hardy et al. 

1980). 

Resource Status 

Abalones are rare in the coastal 

waters between Avi 1 a and Monterey, 

California. The resurgence of the sea 

otter population along the central 

California coast coincided with a 

substantial reduct ion in commercial 

and sport catches for abalones. In 

the 19401s, the 200 miles of coastline 

between Monterey and Point Conception 

produced an annual commercial catch of 

720,000 red abalone (Bonnot 19481, but 

densities of abalones and sea urchins 

fell drastically after the reestablishment of sea otters in the coastal 

waters of Monterey County in the early 

1960's (Lowry and Pearse 1973). Abalone stocks within the sea otter's 

establ ished range are too low for 

prof itable commercial or sport 

fisheries. The relative changes in 

abalone density when sea otters became 

reestablished in 1970 near Point 

Estero are illustrated in Figure 3. 

This area supported a strong commercial fishery from about 1940 to 1970 

(Hardy et al. 1980). The full impact 

of the sea otter on abalone fisheries 

was slow to be recognized by the 

pub1 ic. Sea otters have depleted the 

most productive abalone grounds and 

are a threat to a1 1 abalone populations 

in California (Burge et al. 1975). 

Although the Mar ine Mammal Protect ion 

Act of 1972 categorizes the sea otter 

as a threatened species (Wyner et a1 . 1977), many authorities in California 

believe that it must be contained 

within a restricted range as a 

necessary prerequisite to the 

d~v~lopment of a viable management 

plan for abalone resources in 

California (Wyner et al. 1977; Hardy 

et al. 1980). 

A metal bar of about 12 inches in 

length, 1-112 inches wide, and 1/4 

inch thick is the standard commercial 

and sport diving tool used to collect 

abalones. The tool is used to break 

the suction-vacuum created by the 

abalone's foot against the substrate. In southern and northern 

Cal ifornia (areas outside the sea 
YEAR 

2 Figure 3. Average population densities (number/m ) of red 

abalone at Point Es tero, Cal i fornia , 1965-1978 ( from Hardy 

e t a1 . 1980). 

otter's range), a high percentage of 

the abalones that are removed from the 

substrate by commercial and 

sportd i vers, then rep1 aced because 

they are found to be below legal size, 

die because of iqjury or improper 

rep 1 acement. Abalones are hemocoel s , i.e., the blood sinuses pass through 

the foot. Metal picking bars 

sometimes sever these blood sinuses, 

causing a loss of blood pressure and 

fluids. About 50% of the abalones 

injured (but not removed) by picking 

bars are likely to die (Burge et al. 

1975). Abalones not securely attached 

to the substrate also become easy prey 

for fishes. General declines in 

standing stocks of abalones may be 

caused by catches of abalones below 

legal size and by habitat degradation 

(Hardy et al. 1980). 

In 1984, studies are being conducted to determine the feasibi 1 ity of 

rearing 1- to 2-year-old abalones of 

several species in the laboratory and 

transplanting them into suitable habitats where popu 1 at ions have decl ined. 

Seeding abalone habitat with juveniles 

may prove to be an effective means of 

repopulating formerly product i ve 

waters (Leighton et al. 1981). 

ECOLOGICAL ROLE 

Food and Feeding Habits 

Abalones are herbivores that feed 

largely on brown and red algae, 

somewhat in proportion to its 

availability. Densities are often 

high in locations with abundant algal 

drift or situ kelps. Studies of 

the food and feeding have been reported for black abalone by Leighton and 

Booloot ian (19631, for green abalone 

by Leighton (1966), and for red 

abalone by Leighton (1966, 1968) and 

J.D. DeMartini (pers. comm.). 

Newly hatched abalone have enough 

yolk to last for several days. By the 

time the larva settles, its radula has 

developed sufficiently to enable the 

ingestion of microalgae less than 10 

micrometers long. Abalones less than 

10 mm long usually subsist on a diet 

of sessile pennate diatoms such as 

Navicula and Nitzchia, and some 

bacter ia (Le ighton 1972; Mottet 1978). 
Small abalones (less than 5 mm long) 

graze primarily on benthic microflora 

(Leighton et al. 1981; Olsen 1968b). 

Although small juveniles do not feed 

directly on kelp, kelp beds provide 

cryptic refuges that enhance survival 

of abalones. The young often grow 

well in waters unsuitable for adults. 

A1 though small juveniles prefer to 

feed on seaweeds with thin fronds, 

juveniles as short as 1 cm long can 

eat the same food as adults. When 

kelp is sparse, diatoms may form a 

large part of the adult diet. 

Coastal waters inhabited by abalones off California and Baja California flourish with the Phaeophyta 

(Table 3). The product ion of algae is 

highly seasonal and the amount of 

algae being consumed usual ly reflects 

its availability (J.D. DeMartini, 

pers. corn. ). In northern Cal ifornia 

waters in late fall, annuals begin to 

disintegrate and perennials die back. 

The abundance of food then drops 

sharply and remains low until the 

following spring. At the same time, 

the growth of the abalones drop 

sharply (Leighton and Boolootian 1963; 

J.D. DeMartini, pers. comm.). 

Table 3. Common brown and red algae (kelp) in nearshore waters of southern 

California (south of Point Conception) and northern California (Point Conception to Oregon border). 

Southern Cali forni a Northern Cal i forni a 

Division Phaeophyta 

(Brown algae) 

Cys tosei ra osmundacea 

Desmarestia 1 i gulata 

Egregia menziesii 

Ei seni a arborea 

Hal i drys dioica 

Laminaria sincl ari i 

- 

L. farlowii 

Macrocysti s pyri fera 

Pelagophycus porra 

Pterygophora cali fornica 

Division Rhodophyta 

(Red algae) 

Di vi sion Phaeophyta 

(Brown a1 gae) 

Alaria marginata 

Costaria costata 

Desmarestia 1 igulata 

D. vi ri di s - 

Dictyoneurum cal i forn 

Egregia menziesi i 

Hedophyl 1 um sessile 

Lami nari a den ti gera 

- i cum 

- 

L. -- sinclarii - - - 

- 

Lessoniopsis littoralis 

Macrncvstis ~vrifera ~ ~ ~ 

M. integrifolia - 

Nereocystis 1 uetkeana 

Postel sia palmaeformis 

Pterygophoe cal i fornica 

Di vision Rhodophyta 

(Red algae) 

Botryoglossum far1 owianum 

Gi garti na sp. 

Hymenena sp. 

Tridaea sp. 

Li thothamni on sp , 

Porphyra sp. 

Prionitis sp. 

Rhodymenia sp, 

Schizymenia sp, 
Since some species of algae are 

more nutritious than others, somatic 

and gonadal growth is influenced by 

the species of algae eaten (Leighton 

1968). The coincidence of gonadal 

growth and food supply has been 

observed for both the green abalone 

(Leighton et al. 1981) and the red 

abalone (Leighton 1974; Ault 1982). 

Both ocean and hatchery-reared adults 

can be spawned artificially in the 

1 aboratory every month of the year if 

sufficient food is available. Grazing 

can be selective under certain conditions, and food toughness may influence choice. For example, the more 

resilient, denser algae are eaten at a 

slower rate than the tender tissues 

(Leighton 1966); however, selectivity 

tends to disappear when food is 

scarce. Although bits of drift kelp 

are an important source of food, 

attached kelp also is eaten. 

Abalones feed by raising their 

shell and extending their epipodium 

(Cox1962). When a piece of drift 

touches the epipod ium, the abalone 

turns toward the food and grasps it 

with the highly prehensile anterior 

lobes of the foot. By creating rhythmical contractions of the foot the 

algae is drawn under the anterior half 

of the foot (D.L. Leighton, World 

Research, Inc., San Diego, CA; pers. 

obs. 1. Water current, 1 ight, and 

other stimuli also elicit feeding 

behavior (Olsen 1968a). 

The summer feeding posture of 

abalones could cause easy detachment 

when food is scarce. Thus, abalones 

are commonly depressed onto rock 

surfaces with their epipodial tentacles extended during winter. These 

animals feed only when contacted 

directly by drift algae. 

Black abalone. The black abalone feeds mostly on brown algae, and 

to a lesser extent on red algae. The 

smaller abalones (less than 20 mm 

long) graze on diatom films and coralline algae, but larger ones subsist on 

fragments of algae brought in by waves 

and currents. Under 1 aboratory condi - 

tions black abalone have shown a preference for the brown alga Egregia, 

but Macrocysti s produced the most 

rapid growth. To some extent, shell 

color varies with the diet (Leighton 

1961; Olsen 1968a,b). 

Green abalone. Green abalone 

eat brown algae proportionate to its 

abundance in the algal drift. The 

1 arger brown a1 gae Macrocyst i s and 

Egreia predominate in the diet 

7-%- Leig ton 1966) and produce the best 

growth (Leighton 1979). However, the 

green abalone strongly prefers the red 

algae Gel idium, Pterocladia, Plocam& and Gigartina. Red algae are 

three times more abundant in the diet 

of the green abalone than they are in 

the a1 gal drift (Tutschul te 1976). 

Red abalone. Adult red abalone 

main1 v eat brown macroalaae. Juveniles 

(less- than 20 mm long) graze on diatom 

films or other sessile microscopic 

plants, and the shell's dorsum may be 

pink, bluish-green, or white. Pigmentation of the ostracum reflects the 

diet in nature (Leighton 1961). When 

red algae become predominant in the 

diet, either as consumed kelps or as 

epiphytic growths on consumed kelps, 

the ostracum of the abalone becomes 

reddish. Individuals a1 ternately fed 

red . and brown algae show alternate 

banding of red and white. Color 

sequences in the shells may be used as 

a key to botanical succession in the 

home area of the respective animals. 

Yearly color sequences indicate growth 

rate relative to season and diet 

(Olsen 1968a). At Point Cabrillo, 

Mendocino County, the annual and 

seasonal 1 v abundant s~ecies A1 aria 

mar inata" and ~esma;-esetia liu 

r ..~ .I iaulata account . . - .- 46; 

more than- 65mhe food observed 

being eaten (J.D. DeMartini, pers. 

corn.). South of San Francisco, kelp 

beds of Macrocystis and Nereocystis dominate the diet (CoxTXZ; 

Leiqhton 1968). These kelps are rich 

in -protein and carbohydrates that are 

highly digestible (Leighton 1968). 
Competition and Predation 

Competition between abalones and 

sea urchins in rocky nearshore waters 

is intense. The sea urchin Strongylocentrotus franciscanus is distributed throughout the range of the abalones. ~balones and urchins occupy 

the same general habitats and eat much 

the same food (Leighton 1968), but the 

maintenance demands of abalones are 

three to four times greater than those 

of sea urchins (Leighton 1968). The 

apparent negative kelp growth affected 

by urchins destroys recruiting sporophytes and greatly reduces abalone 

food product ion (Leighton 1966, 1968). 

Abundant sea urchins may completely 

denude kelp plants. In shallow water 

where sea urchins are scarce, kelp and 

other algal growth is usually lush. 

In southern and central California, the small dark-purple shrimp 

Betaeus harfordi is a commensal in 

theantle cavity and the mantle 

groove of green and red abalones; it 

positions itself with its head near 

the abalone's mouth. There is a 

direct correl at ion between the size of 

the abalone and the size of the commensal shrimp (Morris et al. 1980). 

Boring organisms living in carbonate 

matrices often infest the shells of 

abalones. The boring sponcje Cl iona 

celata initially attacks neam 

spire of the abalone shell, then 

riddles the host, reducing the shell 

to a fragile skeleton (Hansen 1970). 

A small clam. the abalone Diddock 

(Penitel 1 a coniadi bores at ' right 

angles into the dorsal aspect of the 

abalone shell (Cox 1962). As the clam 

penetrates the shell and approaches 

the inner surface, the abalone 

secretes nacre locally over the inner 

surface of the shell, forming a 

bl ister pearl (Hansen 1970). 

The mortality of abalones is 

probably greatest in the planktonic 

stages. Those that survive to live on 

the benthos are preyed upon by sea 

stars, crabs, fishes, octopuses, sea 

otters, and man. Some asteroids can 

extend their stomachs completely over 

large abalones (185 mm long) and 

digest them by secreting gastric 

juices through the respiratory pores 

of the abalone. Abalone display 

active escape responses in contact 

with, or in proximity of, the sea 

stars Pvcno~odi -. a he1 i anthoides and 

Pi sas ter ochraceus (Montgomery 

196Q). Abalones attempt to escape by 

making a gal loping retreat coupled 

with repeated 180 degree rotations of 

the shell. By extending the epipodium 

over the shell surface the abalone 

applies a copious amount of mucus to 

the shell, which helps prevent the 

tube feet of the sea star from fastening to the shell (Montgomery 1969). 

The number of actual accounts of sea 

star predation on abalones in relation 

to abalone abundance is so slight that 

asteroids are probably not a serious 

threat under usual conditions; however, under severe oceanic condi t ions, 

when abalones are prone to being 

injured by roll ing boulders, asteroid 

predation may be commonplace. The 

shifting or disturbance of boulders in 

abalone habitat causes an imnedi ate 

but usual ly temporary movement of most 

juvenile and adult abalones. 

Fishes and sea otters sometimes 

catch abalones that have raised their 

shells to catch drift algae. Abalones 

may be dislodged by a sharp bump from 

fishes like the California shee~head. 

Semicossyphus pulcher; cabezon, Wrpaenichth-YS mxmoratus; kelp green1 ing, Hexagramnos decagrammus; kelp 

bass, Para1 abrax ciathratus; or barred 

sand bass, P. nebulifer. They may 

also ~ ~ be disloaaed bv a sea otter or a 

bat-ray, ~;l iobatus cal ifornica, 

which pries them loose with the lower 

jaw. 

Where abundant, sea otters are the 

major predators of 1 arge abalones, 

preferring them over all other foods 

(Hardy et al. 1980; Hines and Pearse 

1982). The sea otters use rocks to 

break the top of an abalone shell, 

exposing the soft body parts. Because 

of this intense predation, abalone 
populations are restricted in distribution to cryptic microhabitats and 

older abalones are relatively scarce 

(Hines and Pearse 1982). Octopuses are 

capable of pulling small abalones from 

the rocks, or drilling through the 

shell of abalones of all sizes. Man 

is a long-t ime predator on abalones 

(Cox 1962). 

ENVIRONMENTAL REQUIREMENTS 

Temperature 

The vertical and latitudinal distribution of abalones is most closely 

related to water temperature (Cox 

1962; Leighton 1974). The distribution of juveniles and adults of each 

abalone species corresponds well with 

thermal tolerances observed in the 

1 aboratory (Leighton 1974). Their 

tolerance increases with age. Larvae 

that have the best chance of survival 

live in water(s) with optimum temperature and settle in areas where temperature changes are not excessive 

(Leighton 1974). 

The thermal optima foro the red 

abalone is between 14 and 18 C (Leighton 1974). The optimal temperature 

for egg fertilization is apparently 15 

OC (Ebert and Hamilton 1983). Red 

abalone eggs develop normally within a 

temperature range of 10-23 OC, but 

optimum larval growth is at 13.5-20'~. 

At 18 OC, larvae settle in about 5 

days. Larval growth is temperature 

dependent; only larvae reared between 

14 and 18 OC reached the advanced 

post-larval stages (Leighton 1974). 

The red abaione feeds at temperature5 

of 7 to 22 C, but maxJmum feeding 

is between 13 and 18 C (Leighton 

1968). Growth was fastest ato temperatures between 15 and 20 C and w8s 

only slightly less at 12.5 C 

(Leighton 1974). I 

The black abalone is an intertidal species that lives over a 

broader 1 ati tudinal range than red 

or green abalones, yet the thermal 

requirements of red and black abalones 

are similar (Leighton 1974). 

Larval and juvenile green abaloze 

grow and survive well at 20 to 28 C 

(Leighton et al. 1981), but the 

optiym temperature is between 18 and 

24 C (Leighton 1974). The time 

required for qreen abalone larvae to 

reach the sett ing stage varies from 

3.5 days at 24 "C to 12 days at 14 "C. 

Larvae incubated at 12 "C failed to 

settle within 2 weeks (Leighton et al. 

1981). Young laboratory-reared green 

abalone grew fastest at temperatures of 

22 to 28 "C. When postlarvae were 

reared at near optimal thermal and 

feeding conditions, they formed the 

respiratory pore in about half the time 

required by other California abalones 

(Leighton 1974). The "notch stage" was 

reached in some rapid-growing green 

abalones within 30 days after fertiliza tion. Juveniles usual ly 1 ive beneath 

rocks and in crevices in the lower 

intertidal zone where they are exposed 

to temperatures of about 12 to 26 "C. 

In one experiment, the growth rates of 

juve!i les in thermal effluent (22- 

28 C) were increased twofold over 

those reared at ambient temperatures 

(14-20 OC). Increases in shell growth 

are linearly dependent on temperature 

(Leighton et al. 1981). Green abalones grow fastest in water at about 

26 OC. The optimal thermal range for 

somatic growth declines with age, 

corresponding with the lower temperatures in the sublittoral areas occupied by adults (Leighton et al. 1981). 

Depth 

The black abalone lives higher in 

the intertidal zone than any other 

California species. It ranges from 

the mid-intertidal zone to about 3 m 

below mean low tide. 

The habitat of green abalone 

usually extends from the intertidal 

zone to a depth of about 20 m; however, few of the animals live below 

10 m. They are most abundant at 

depths of 2 to 3 m below mean low tide 
in areas of high turbulence, strong 

surge, and suitable crevice refuge. 

In northern California,. red abalone inhabit water from 0 to 35m 

deep, but concentrate in water 1 to 

6 m deep. In Morro Bay, central 

California, the red abalone lives in 

intertidal waters up to 30 m deep 

(maximum concentrations are between 5 

and 17 m), and as far as 2 miles offshore if there is abundant rocky 

substrate and food supply (Cox 1962). 

Near San Diego, California, red 

abalone usually 1 ive in water 8-40 m 

deep; maximum c o n c e n t r a t i o n s a r e 

between 12 to 15 m. Although red abalone are re1 at ively abundant off 

southern California and Mexico, they 

are seldom encountered at depths less 

than 12 m (Cox 19621, and are usually 

restricted to rock bottoms 10 to 30 m 

deep (Leighton 1968). This depth 

distribution correlates with an extended phot ic zone, generally higher 

algal product ion, and more suitable 

temperatures at greater depths. 

Other Environmental Requirements 

In waters north of San Francisco, 

abalones occupy a narrow coastal band, 

restricted to the nearshore waters 

where either drift or attached kelp is 

available for food. Along the coasts 

of Sonoma and Mendocino Counties in 

northern Cal iforn i a, abalones are common below the algal zone, especially 

along the bottoms of surge channels, 

and are not always near attached 

algae. The availability of drift 

macroalgae var ies dai ly. Water movement is essential for transport ing 

food that abalones can catch (Olsen 

1968a). Abalones in deep water (20- 

30 m) 1 ive in channels serving as funnels for drift kelp transported from 

shal low water. In southern Cal iforn i a 

these underwater channels bear a 

strong resemblance to terrestrial 

desert washes (J.S. Ault, author, 

pers. obs.). Along a coastline with 

adjacent surge channels, abalones are 

characteristically further offshore. 

This more seaward distribution is correlated with greater kelp abundance 

there, either adrift or attached 

(01 sen 1968b). Abalones are scarce 

where channels widen and currents 

become diffuse. 

A1 though much rocky habitat is 

comon along the coasts of Humboldt 

and Del Norte counties in the extreme 

north of California, these coastlines 

are highly exposed, and abalones are 

scarce north of She1 ter Cove, Humboldt 

County. In winter, overlying waters 

are sometimes excessively turbid due 

to high freshwater inflow. Unusual ly 

large freshwater inflows near river 

mouthsmaykill all abalones in the 

immediate vicinity (Bonnot 19483. If 

the water is turbid too long, most 

brown algae in waters 6 m or less 

below mean low tide are excessively 

shaded and die. In addition, excessive exposure to swell and sand 

abrasion inhibits sporophyte recruitment and reduces the product ion and 

availability of algae. The shifting of 

sand by strong bottom currents somet imes smothers 1 arge numbers of abalones (Bonnot 1948). The deepest that 

abalones are found north of Shelter 

Cove is about 6 m; consequently most 

of their habitat is subt idal. They 

inhabit even shallower water if food 

is abundant there. 

Abalones are relatively scarce in 

the two most northern counties of 

coastal Cal iforn i a because food and 

surge channels are both scarce. 

Surveys off the coast of San Diego and 

Santa Barbara revealed that small 

rocks encrusted with patches of coralline red algae frequently served as 

nursery grounds for juveni le red abalones and other species of Haliotis 

(Morse et al. 1980). These areas are 

scarce in the two northernmost 

counties of northern Cal iforn i a. 

Abalone larvae there may have drifted 

from the more productive waters to the 

south (J.D. DeMartini, pers. comm.). 
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183-193. 

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70(2) :373-381. 

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juvenile growth in three species 

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1963. Diet and qrowth in the 

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development and growth in young 

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Lowry, L.F., and J.S. . Pearse. 1973. 

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area inhabited by sea otters. 

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two Hal iot id qastro~ods (Moll usca) , ~aliotis ' assimi l is 

and Haliotis rufescens. to 

the forci~ulate asteroids chinodermata) , Pycnopodi a He1 i anthoides and Pisaster ochra- 

- 

ceus. Vel iger 9(4):359-368. 

Morris, R.H., D.P. Abott, and E.L. 

Haderl ie. 1980. Intertidal 

invertebrates of California. Stanford University Press, Stanford, 

Calif. 190 pp. 

Morse, D.E., N. Hooker, L. Jensen, and 

H. Duncan. 1979. Induction of 

larval abalone settling and metamorphosis by gamma-aminobutyric 

acid and its congeners from crustose red algae. 11. Applications 

to cultivation, seed-production 

and bioassays; principal causes 

of mortal i ty and interference. J. 

World Maricul. Soc. 10:81-91. 

Morse, D.E., M. Tegner, H. Duncan, N. 

Hooker, G. Trevelyan, and A. Cameron. 1980. Induction of settling and metamorphosis of planktonic moll uscan (Haliotis) 

larvae. 111. Signaling by metabol ites of intact algae is dependent on contact. Pages 67-86 

- 

in D. Mu1 ler-Schwarze and 

R. M. Silverstein, eds. Chemical 

signals. Plenum Publ. Corp. , New 

York. 

Mottet, M.G. 1978. A review of the 

fishery biology of abalones. 

Wash. Dep. Fish. Tech. Rep. No. 

37. 81 pp. 

Olsen, D.A. 1968a. Banding patterns 

of Haliotis rufescens as indicators of botanical and animal 

succession. Biol. Bull. (Woods 

Hole) 134(1):139-147. 

Olsen, D.A. 1968b. Banding patterns 

in Haliotis. 11. Some behavioral considerations and the effect of diet on shell coloration 

for Hal iotis rufescens, Hal iotis 

corraqata, Hal iotis sorenseni, 

and Haliotis assimilis. Veliger 

11 (2) : 135-139. 

Price, P.S. 1974. Aspects of the 

reproductive cycle of the red abalone. M.S. Thesis, San Diego 

State University, San Diego, 

Calif. 64 pp. 
Sevilla, M.L., H. Hernandez, E. Mondragon, D.N. Farran, A. Giovanini, 

and A. Hernandez. 1965. Estudio 

histologico comparativo de algunos moluscos de importancia economica en Mexico. Inst. Nac. 

Invest. Biol. Pesqs. 3(22): 1-19. 

Tutschulte, T.C. 1976. The comparative ecology of three sympatric 

abalones. Ph.D. Dissertation. 

University of Cal ifornia, San 

Diego. 335 pp. 

Tutschulte, T.C., and J.H. Connell. 

1981. Reproductive biology of 

three species of abalones (Haliotis) in southern California. 

Veliger 23:195-206. 

Webber, H.H., and A.C. Giese. 1969. 

Reproductive cycle and gametogenesis in the black abalone, 

Haliotis cracherodii (Gastropoda, 

Prosobranchiata). Mar. Biol. 

(Berl . ) 4(2): 152-159. 

Wyner, A.J., J.E. Moore, and B. CicinSain. 1977. Politics and management of the California abalone 

fishery. Mar. Policy 1(4):326- 

339. 

Young, J.S., and J.D. DeMartini. 1970. 

The reproductive cycle, gonadal 

histology, and gametogenesis of 

the red abalone, Hal iotis rufes 

tens Swainson. Cal if. Fish Game 

56(4):298-309. 
SO172 -101 

Id S. Ault 

b. hflormln# O~anlzatlon Name and Addrasm 10. ~miM/TasklWor~ Unlt No. 

Cooperative Institute for Marine and Atmospheric Studies 

4600 Rickenbacker Causeway 11. Contmct(C) or Crant(G) NO. 

Miami , FL 33149 

REPORT DOCUMENTATION 1. "Emrn NO. 2 

PAGE I Biological Report 82(11.32)* ( 

I 

4. nth and mt~t~. 

Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Paci fic SouthC rrppn. and Red unes 

It Spanwrlng Organlxatlon Name and Addms I 

3. Rec~p~ern's Accesston NO 

S. R*porl 

March 1985 

L 

a Paflorming Omanlxat~on ~ept. NO. 

National Coastal Ecosystems Team U.S. Army Corps of Engineers 12 TY~. a( Repaft • hrlod hnd 

Fish and Wildlife Service Waterways Experiment Station 

U.S. Department of the Interior P.O. Box 631 

Washington, DC 20240 Vicksburg, MS 39180 

16. 

IS. 

* U.S. 

Atmtre 

Supplementav 

Army 

(Limit 

Corps 

Notes 

100 worm) 

of Engineers 

Black, green, 

Report 

and 

No. 

red 

TR 

abalones (Hal 

EL-82-4 

iotis cracherodi 

- 

i , K. fulqens, 

and K. rufescens, respective1 y) are of commercial and ecological importance and are 

distributed widely along the California coast. The abalones are morphologically similar; 

species are distinguished by particular shell sculpture, color, and body characteristics. 

Their latitudinal and bathymetric distribution is stratified and most closely related to 

temperature. Small juveniles eat mainly microflora; adults eat primarily drift macroa1 gae, preferring specific brown or red a1 gae, when available. Spawning occurs during 

summer; gonad ripening depends on food quality and quantity and water temperature. 

Larvae are lecithotrophic and remain planktonic forperiods of 5 to 14 days after 

hatching; settling is substrate specific. Postlarvae and adults require hard substrate 

for attachment. Juveniles are cryptic, adults usually more exposed. Growth rates are 

similar, although maximum size varies with species. Increases in shell length and body 

weight correlate positively with food abundance and temperature. Be1 ow depths of 6 m, 

sea urchins are major competitors for food and space. Predation by invertebrates is low. 

Decreased abalone production from central California is associated with range expansion 

and increased- predation by sea otters, the major source of abalone mortality. General 

declines in California landings are due to mortality from improper picking and replacement, habitat degradation, and perhaps overfishing. Commercial and sport diving efforts 

have increased sharp1 y, whereas annual landings of abalones decl ined from 1965 to 1982. 

17. Document Anal-is a. Descriptors I 

Shell fish Food habits 

Distribution Growth 

Age 

b. IQentlfienlOoen-Ended Terms 

Predation 

Life historv 

Hal ioti s cracherodi i. 

Green abalone 

Habitat r&$i rements Hal iotis fulgens 

Black abalone Red abalone C. COSATI FieldlCroup Hal iotis rufescens 

la Aveilablllty Statement 19. Sccunty Class Chis 'IewrO 21. No. of Pages 

Unlimited I Unclassified 19 I n security class mis pa e) 

- 

ZL P"C* 

unclassified iee ANS1-239.18) OPTIONAL CORY 272 (4-771 

(Fornrrly NTIS-35) 

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