AN INNOVATIVE METHOD FOR SEEDING ABALONE

AND RESULTS OF LABORATORY AND FIELD TRIALS

A Thesis

Presented to

The Faculty of the Department of Biology

San Jose State University

In Partial Fulfillment

of the Requirements for the Degree

Master of Arts

By

Thomas B. Ebert

August, 19 8 6

ABSTRACT

In recent years the California abalone fishery has

undergone a severe decline.· However, present technology

offers an opportunity for rehabilitation and enhancement of

this once valuable fishery resource. Because the biology and

technology for producing and cultivating abalone is well

developed, sufficient quantities of juvenile abalone are

available for seeding programs. Previous efforts to

rehabilitate once productive abalone fishing grounds have

failed, met with limited success, or have been of

questionable value. These enhancement efforts were conducted

by divers who generally hand-planted the abalone in crevices.

This method is not only unwieldy and labor intensive; but the

planted abalone are generally stressed, and often are highly

vulnerable to predators. In an effort to rectify this

problem a new abalone planting method has been designed,

tested and appears promising. This method employs a "seeding

module'' which is designed to serve as an intermediate habitat

for the abalone, and retains them for a predetermined

acclimation time prior to their release and dispersal.

Evaluation of this technique indicates that site selection,

abalone size, and season are critically important factors.

However, if the appropriate criteria are met then high

abalone survivorship and an enhanced fishery resource should

result. iii

ABSTRACT, • • •

LIST OF TABLES

LIST OF FIGURES

ACKNOWLEDGEMENTS

INTRODUCTION

METHODS AND MATERIALS

TABLE OF CONTENTS

..

Abalone Seeding Module Design and Operation

Abalone Collector-Transporter

Page

iii

v

vi

vii

1

8

8

9

Abalone Species Selection and Shell Coloration. 10

Laboratory Studies. ll

Field Studies 13

RESULTS • • 17

Seeding Module Performance. 17

Laboratory Trials • 18

Initial Trial Series 18

Second Trial Series. 19

Field Trials ••

Seeding Module Site.

Control Site

DISCUSSION.

LITERATURE CITED.

TABLES.

FIGURES • •

iv

20

21

24

27

39

42

56

LIST OF TABLES

Table Page

1. Abalone tLansplants and seeding efforts in

CalifoLnia, exclusive of abalones seeded

in private enterpLise leased sites,l956-B6.

2. Laboratory dispersal Late of Led abalone from

the seeding module. • • . •••••

3. Number of red abalone observed on concrete block

habitats with and without giant kelp ••••

4. Red abalone found inside of the seeding module

during weekly suLveys at the field study site

in Carmel Bay. TheLe were 250 of each size

• 42

• 49

• 50

class abalone released for every trial ••••• 51

5. Empty red abalone seed shells recovered during

weekly surveys at the field study sites in

Carmel Bay. . • • • • . . . . . 6. Live red abalone recovered, percent showing shell

growth, and percent unaccounted for, after

four weeks from the field study sites in

. 52

Carmel Bay. . • . . . . . . . . .. • • 54

7. Locomotory rates for three size groups of

hatchery-reared red abalone on plastic

laboratory tank surfaces. ~ • • 55

LIST 01!' FIGURES

Figure Page

1. The abalone seeding module with cut-away section

showing the temporary door interior with

astroturf and the ~agnesium link attachment.

2. The collector-transporter used for translocating

abalones from the laboratory to the field.

overall, are 50

• 56

Not to scale. Dimensions,

em by 31 em by 19 em high. .. .. • 57

3. A schematic diagram of the 2.3 m diameter tank

floor layout used to measure abalone

dispersal rates and patterns

4. Dispersal rate of the red abalone from the

seeding module during laboratory trials.

vi

• .. 58

• .. • 59

ACKNOWLEDGEMENTS

I am grateful to the following people for their time

and effort given throughout this study. David Ebert, Jim

Houk, and David VenTresca for their helpful comments,

suggestions, and diving assistance. The members of my thesis

committee James Nybakken, Mike Foster, and John Oliver for

their helpful suggestions and comments in reviewing this

manuscript. Melanie Mayer and Al Miller provided diving

assistance. Special thanks to my parents, Earl and Peggy

Ebert, for their constant support throughout my educational

endeavors. Additionally, I would like to extend my sincere

appreciation to my father for serving as my guiding light

throughout every portion of this research, and to whom I

dedicate this thesis.

This work was supported in part by a Packard

Foundation research grant.

vii

INTHODUCTION

Abalones, Haliotis spp., comprise an important

shellfish resource to Califqrnia. Seven species and one

subspecies occur (Owen et al. 1971). Of the seven species,

five, the white, sorensoni, green, H. pink, ~-

corrugata , black, ~· cracherodii, and red, H. rufescens are

generally sought by fishermen. The remaining three, the

flat, ~- walallensis, pinto, H. kamtchatkana, and threaded,

H. k. assimilis, are usually smaller in size, more cryptic,

and typically taken incidentally. They are generally prized

more for their shells than their consumptive value. However,

the pinto abalone is the object of a limited commercial

fishery in British Columbia. The pink, green, and white

abalones are generally considered warmer water species which

are endemic to southern California and Baja California; while

the black inhabits the shallowest depths (principally the

intertidal zone), from central Baja California to northern

California, but is uncommon north a£ San Francisco.

The red abalone ranges from central Baja California

to southern Oregon (Cox 1962) and is highly prized by sport

and commercial fishermen. It occasionally exceeds 29 em in

length (Cox 1962) and is the largest abalone species. The

red abalone is the principal species taken by skin divers and

shore pickers in northern California and represents one of

2

the most important sport fisheries in that region (Burge,

Schultz and Odemar 1975, Schultz 1984). Along the California

coast commercial fishing is permitted from the

California-Mexican border to Yankee Point, Monterey County,

and from Pigeon Point, San ~ateo County, to Point Lobos, San

Francisco and the Farallon Islands.

Commercial fishery landings of red abalone have

steadily declined since 1967 when nearly 2.7 million pounds

were landed. By 1985 this valuable fishery yielded less than

G.4 million pounds (Calif. Dept. of Fish and Game, report of

annual comm. lndgs.); approximately 15% of former long-term

annual production. Historically, during the peak production

years, the major commercial fishing grounds for red abalone

were located along the central California coast from Monterey

to Point San Luis. Morro Bay represented the center of the

fishery, and the majority of the catch, exceeding 1 million

pounds annually, was landed there (Cox 1962, Miller 1974,

Burge and Schultz 1973). This fishery persisted through the

1961's and into the early 1970's (Miller 1974, Burge et al.

1975). The demise of the central California fishery was due

to the sea otter, a major predator of abalone (Ebert 1968a,

b, Burge and Schultz 1973, Miller 1974, Burge et al. 1975).

Presently, no red abalone are taken commercially from the

central California coast, nor are any landed at Morro Bay.

Red abalone populations have declined elsewhere in

California principally due to human-related factors (Burge et

3

al. 1975, Tegner et al. 1981, Hardy, Wendell and DeMartini

1982). These include over-exploitation, habitat degradation

and perhaps competition with sea urchins. A limited entry

commercial abalone fishery and further restrictions on the

sport fishery were instituted in 1976 (Hardy et al. 1982,

Schultz 1984). However, stocks have continued to decline and

in 1985 legislation was instituted which provides for even

greater restrictions on the commercial fishery.

To augment this valuable but declining resource the

California Department of Fish and Game (CDFG), university

scientists, and commercial abalone fishermen have conducted

various restoration and/or enhancement projects (Cox 1962,

Ebert and Houk 1984, Tegner and Butler 1985 ) • An initial

effort to enhance the red abalone resource was made in 1956

when the CDFG attempted to establish a red abalone population

at Santa Catalina Island, off southern California (Cox 1962).

This transplant was unsuccessful. The development of abalone

hatcheries in California during the late 1960's and early

1970's (Ebert and Houk 1984) provided a seed source for

fishery enhancement investigations. The first seeding

attempt using hatchery-reared red abalone in California was

made in 1968, near Point Estero (CDFG unpubl. data). This

was a small-scale experiment (500 red abalone averaging 15 mm

in length) to test feasibility. The abalone were distributed

within an artificial habitat comprised of nine concrete

slabs, each 40 em by 40 em by 3 em thick, arranged in a stack

4

with 1.5 ern spaces between each slab. Unfortunately, the

abalone rapidly dispersed from this habitat and their fate

was not determined. Following this another small scale

seeding experiment, using juvenile red abalone (6-14 mm) took

place at Avila in 1972 (CDFG unpubl. data). The results of

this seeding experiment were similar to the earlier effort in

that the juvenile abalone rapidly dispersed from the seeding

site and were not observed thereafter. In the mid-1970's

relatively large numbers of green and pink adult abalone were

transplanted into areas along the Orange county (southern

California) coast by CDFG, and the first major abalone

seeding effort (14,000 hatchery grown juvenile red abalone)

was made (Table 1). A subsequent survey, 1 year later,

revealed that this seeding effort was not successful. Also,

an abalone seeding association was formed by a group of

commercial abalone fishermen and processors in late 1974 with

intentions of hatching and seeding abalone larvae as a means

to augment the fishery (Ebert and Houk 1984). However, the

results of these endeavors are not known, and presumably

would have been difficult to measure.

In 1976, a small-scale abalone enhancement project

commenced in Ventura County (Fox and McMullen 1981, unpubl.

report to Ventura Co. per agreement dated 3 August 1976).

About 10,000 red abalone were seeded during this project.

But, once again, follow-up surveys revealed few abalone, live

or dead. It was surmised that the abalone had dispersed from

5

the study area or were too cryptic to be located.

Fox and McMullen (1981) did design and test an

intermediate abalone habitat. This habitat consisted of a

roll of plastic screening, 12 em in diameter by 60 em long,

that held 1000 abalone, 5-l~ mm long. Newspaper was stuffed

in either end of the habitat to contain the abalone. The

abalone escaped upon disintegration of the newspaper.

However, the habitat was lost during the study and the

effectiveness of this abalone seeding method could not be

evaluated.

In 1977, an experimental abalone enhancement program

was inaugurated by CDFG and the Oniversity of California Sea

Grant Program (Tegner et al. 1981). This program focused on

southern California and was buttressed by an abalone fishery

moratorium along the coast, from Palos Verdes Point, Los

Angeles Co., to Dana Point, Orange Co., to allow populations

to rebuild. This joint effort was undertaken to determine

the biological and economic feasibility for enhancing

depleted abalone populations by transplanting adults and

seeding smaller size, hatchery-reared, red, pink, and green

abalones. Relatively large numbers of abalones were seeded

and transplanted during this program.

In all, since 1956 over 25,000 adult abalones have

been transplanted, and more than 200,000 hatchery-reared

abalone have been seeded in California, exclusive of private

enterprise lessors (Table 1). However, about 61% of those

6

abalone transplanted came from the Diablo Cove region (Table

l) where a nuclear power plant was under construction, and

posed a threat to these abalone.

Although relatively large numbers of abalones have

been transplanted or seeded jn California, on an experimental

basis, their survivorship, and ultimate contribution to

resource enhancement has been difficult to assess (Tegner

and Butler 1985). As a consequence, abalone seeding and

transplanting as a means to enhance the resource remains

questionable from a biological standpoint, and an economic

assessment has not, or cannot yet be made.

Other countries, primarily Japan, are presently

investigating the feasibility of enhancing abalone

populations through seeding programs because of declining

natural stocks ( Kan-no 1975, Inoue 1976, Mottet 1978).

Moreover, the Japanese government has promoted abalone stock

enhancement since the beginning of the Maiji Restoration in

the 19th Century (!no 1966). Interestingly, abalone

enhancement efforts in Japan appear to be more successful

than similar projects conducted in California. However,

Japan's techniques are generally no~ applicable here because

their abalone harvest is largely controlled by fishery

cooperatives and they do not permit a sport fishery

(Cicin-Sain et al. 1982).

Over- shing of abalone stocks has been a problem in

every country where commercial fisheries exist (Mottet 1978).

7

In attempts to rebuild these fisheries it has become common

practice to seed areas with juveniles. Par economic and

practical reasons small abalones from l to 3 ern long are

usually obtained from hatcheries for seeding purposes (Mottet

1981). Prior investigations suggest that the survival of

hatchery-reared abalone in the field is directly related to

size. For example, an experiment conducted in Japan involved

the release of two size groups of abalone (15 and 21 mrn) in

concrete cribs which were filled with 30-50 ern diameter rocks

and partially covered with a protective lattice. After eight

months the survival rates of the two size groups were 16.5%

and 33.4%, respectively (Momma et al. 1980, Mottet 1984).

Efforts to seed juvenile abalone for population

enhancement in California were not only unwieldy and archaic

but the abalone were generally stressed, and as a

consequence, more vulnerable to predation before acclimating

to their new environment. These factors served as an impetus

to this study. My objective was to develop a more efficient

approach to seed juvenile abalone. I describe a

collector-transporter/seeding module method which was

developed to provide an expedient method for transporting and

seeding relatively large numbers of juvenile abalone.

Laboratory and field trials were conducted to determine the

efficacy of this method.

METHODS AND MATERIALS

Abalone Seeding Module Design and Operations

The seeding rnodul~ 6onsists of a concrete utility

box, commercially available, that is commonly used in water

and gas meter applications. The utility box dimensions are

71 ern by 47 ern by 28 ern high (Figure l). It was modified by

adding a 5 ern thick concrete base, and by cutting-out a 5 ern

x 22 em section at each end to provide abalone egress. A PVC

casement was fitted around both of these passageways using

l/4-inch thick PVC 90 degree angle stock that was glued

directly to the concrete. These passageways were partitioned

into four openings, each measuring 5 ern long by 4 ern high,

using l/4-inch thick PVC strips. These partitions served to

restrict large predators (e.g. most bony fish, large

Pycnopodia, large crabs, and Kelletia kellettii) from

entering the seeding module, yet allowed egress of abalones

up to 6 ern in length.

Temporary doors were fitted in both passageways.

They were made using l/4-inch thick perforated PVC plastic

sheeting and were 30 ern long by 8 ern high. Astroturf was

cemented to the door interiors to inhibit abalone attachment.

The abalone could therefore not impede water circulation by

covering the door perforations, nor could they block the

doors from opening by adhering to the door jambs.

8

9

Both doors were held in place under tension (53-71

newtons), with two 20 em lengths of latex rubber tubing.

This was done by fastening one end of each tubing length to

opposite doors, then pulling the "free" ends of the tubing

lengths together, and innerconnecting them with a magnesium

link. Plastic cable ties were used to Easten the tubing ends

to the doors and the magnesium link. Dissolution of the

magnesium link in seawater ultimately released the doors. A

series of tests was performed with various size magnesium

links to measure decay rates at various seawater

temperatures. A buoy was attached exteriorly to each door

via a l/8-inch diameter nylon line l m long. Between the

buoy and door the nylon cord passed through a nylon lifting

loop that was attached to the lid (1 lifting loop/buoy).

When the doors were released they floated up, away from the

module passageway, and were retained by the lifting loops.

The temporary doors were installed just before the abalone

are introduced to the seeding module.

Abalone Collector-Transporter

An abalone collector-transporter was designed and

fabricated to provide a substrate for the abalone while in

transit and in the seeding module. The collector-transporter

was made from four, 50 em long PVC pipe sections, of four

different diameters (4,6,8 and Hl-inch), that were cut in

~alf length-wise. These were stacked one directly above the

other (smallest diameter pipe on the bottom), and fastened

10

together near either end, using 3/4-inch by 5-inch long PVC

bolts. This configuration provided about a 2 em to 3 em space

between each pipe section for the abalones (Figure 2).

Astroturf was affixed to the collector-transporter base. This

served two purposes; (i) it prevented abalone from adhering to

this surface where they could be crushed when the

collector-transporter was positioned in the seeding module

following transit and(ii) it presented a good friction surface

with the concrete. This minimized the potential for the

collector-transporter to shift position in the seeding module,

particularly when subjected to severe seawater surge

conditions, and possibly injure the contained abalone. The

abalone collector-transporter was designed to accommodate 500

to 1000 juvenile abalone in the size range of 15 to 30 mm. A

seeding module accommodates only one collector-transporter.

Abalone Species Selection and Shell Color

The red abalone was selected for testing because it was

readily available, economically is the most valuable to the

fishery resource, and because stocks have been seriously

depleted in some areas. The animals used for this study were

hatchery-reared and supplied by the CDFG, Marine Resources

Laboratory (MRL), Granite Canyon.

It is well known that diet influences the shell

coloration of abalone (Leighton 1961, Olsen 1968). Since the

hatchery-reared abalone used during this study were fed

predominantly giant kelp, Macrocystis spp., their shell

ll

color was typically aquamarine. By contrast, native red

abalone typically exhibit a sepia shell color. Therefore,

the shell coloration of hatchery-reared abalone used for this

study served as a useful "tag'' for field identification from

the natural population, and.could also be used for subsequent

growth rate information.

Laboratory Studies

Laboratory studies with the abalone seeding module

were conducted in a circular, 2.4 m diameter, fiberglass

tank. Ambient temperature seawater (12-l5°C) was provided at

a 16 litre/min. flow rate. To simulate the natural

environment cobbles and boulders, with attached biota, were

collected from the adjacent low intertidal region and were

distributed on the tank floor. Additional substrate consisted

of four hollow concrete blocks that were spaced equidistant

around the tank floor perimeter. Sand patches fronted each

concrete block, and giant kelp fronds were anchored to two

of the concrete blocks. This arrangement of substrates and

kelp (Figure 3) was used to determine abalone dispersal

patterns, substrate preferences, and the influence of forage

(kelp).

With one exception, two abalone size groups were

used for laboratory trials. These averaged 10 mm (range=B-12

mm), and 20 mm (range=l8-22 rnm) shell lengths, and 250 of

each size group were used per trial. The one variant

abalone size group trial comprised 554 individuals with a

12

mean length of 32 mm (range=24-45 mm). The abalone used for

all trials were first contained and acclimated in the seeding

module through two nocturnal periods. A magnesium link size

was selected that would decay (according to seawater

temperature) separate, and release the seeding module doors in

the late afternoon-earlyevening period, just prior to the third

nocturnal period of abalone containment. This release time was

selected because it corresponds to a known rise in abalone

activity that has been observed in laboratory and field

populations (T.Ebert, pers. obser.).

An initial series of seven trials were made in the tank to

measure abalone dispersal rates and movement patterns from the

seeding module according to abalone size. They spanned

1,2,2,4,5,7 and 8 nocturnal periods post-abalone release. The

second 2 day release period (noted above) was conducted for the

larger abalone size group (mean length=32 mm). All abalone

were recovered at the end of each trial and their location

plotted diagramatically on a data sheet.

Following the initial series of trials a longer term trial

(28 days) 14as conducted. Only the 10 mm and 20 mm mean length

abalone size groups were used for this trial; 250 of each size

group. Also, post-release observations were made daily,

occasionally at night, but the abalone were not removed. The

tank was drained daily and all abalone were enumerated

according to size and location inside and outside of the

seeding module for the trial duration. This trial was

duplicated using two "fresh" abalone size groups.

Field Studies

13

Field studies were conducted in Stillwater Cove,

Carmel Bay (lat 36°34' N,long 121°56' W). All observations

were made with SCUBA. These studies were designed

principally to compare abalone behavior and survivorship

according to seeding method. The study area consisted of two

sites SB m apart, at a 7 m depth. An abalone seeding module

was placed at one site, while the other site (control) lacked

a seeding module. Abalone seeded at the control site

followed "established'' practices, i.e. the abalone were

allowed to attach to adult abalone shells in the laboratory,

about lB-15 per shell, transported to the control site and

hand-planted while on the adult shells, in rock crevices. In

the experimental set-up, the abalone collector-transporter

was used to hold and transport abalone to the seeding module.

Physical relief at both study sites was similar and

consisted principally of cobbles with a few scattered

boulders on a pavement-like rock base. A thin layer of

coarse sand and shell debris filled depressions and

interstices that cris-crossed the stratum. The most obvious

difference in physical relief between the two sites was the

presence of two large boulders, about l m in diameter, at the

control site. These served as the site reference point. The

seeding module served as a reference point at the other site.

Bach study site area was circular and encompassed about 28

14

meters squared. Area limits were defined by attaching one end

of a 3 m line to the site reference point, and moving the

extended opposite end 360 degrees around the perimeter.

The biota in the general study area also was "

characterized. Dominant algde included Macrocystis, the major

canopy forming species in this region, and important

nutritionally for abalone. Predominant brown algae in the

understory were Laminaria setchellii and Pterygophora

californica while Botryoglossum farlowianum, Gigartina spp.

and Rhodyrnenia spp. were the most conspicuous red algae.

Articulated and crustose coralline algae were major turf

components.

Known juvenile abalone predators in the general study

area, although not necessarily documented during initial

surveys, included the cabezon, Scorpaenichthys mamoratus,

crabs, Cancer spp., Loxorhynchus spp., Paguristes spp., various

sea stars (Pisaster spp., Orthasterias koehleri, and Pycnopodia

helianthoides ) and octopuses, (Octopus spp).

To assess the more cryptic Octopus spp. population,

traps were designed, fabricated and deployed. These consisted

of PVC pipe sections, about 36 em long, of three diameters

(about 2.5 em, 3.8 em and 5.1 em), capped at one end, with a

coupling inserted near the capped end to facilitate octopus

removal. Three traps, one of each size, were deployed at each

study site.

15

Neither study site was considered optimum juvenile

abalone habitat, principally because they lacked the deep

crevices and boulder undersides that offer good protective

niches. However, the sites were selected because they

offered adequate juvenile abalone habitat, and good potential

for critical observations, and enumeration, of those abalone

present.

Three field trials were conducted using 10 mm

(range=B-12 mm) and 20 mm (range=l8-22 mm) abalone; 250 of

each size group at each site (total of 500 abalone per site)

for each trial. The abalone were transported from the

laboratory to the study site, out-of-water, in styrofoam

containers following procedures developed at the MRL. These

consist of putting the abalone and their substrates (adult

abalone shells or collector-transporter) in a plastic bag,

adding seawater moistened sponges, filling the plastic bag

with pure oxygen and sealing it. One or two refrigerant bags

(Blue Ice) are placed on the bottom of each chest, followed

by 5-6 layers of newspaper to insulate the abalone from close

contact with the refrigerant. Transit time from the

laboratory to the study site, and placement of the abalone in

the seeding module, for each trial, took about 2 hours,

Post abalone seeding observations commenced two days

after seeding, just prior to and immediately following door

release. Observations were made at both sites weekly,

thereafter, but with a minimum of perturbations. These

16

surveys included, (i) a general qualitative assessment of the

biota, (ii) qualitative and quantitative observations of

abalone distributions and dispersal patterns, (iii) removal

of dead abalone (empty shells) and noting when possible, the

cause of mortality, (iv) op~ning the seeding module lid to

determine abalone dispersal rates and to check for abalone

predators, and (v) examination of octopus traps. Four weeks

after abalone release both sites were destructively surveyed.

This entailed critical examination, and disturbance of all

abalone habitat, where physically possible, throughout the 28

meters squared study site. For trial one all live abalone

found were noted according to position, but not removed,

examined for growth, and marked with a grease pencil. During

the next two trials all located abalone were recovered.

These abalone were distinguished Erom the trial one group

because they were not marked and exhibited significantly less

post-seeding growth. Also, a less intensive extralimital

survey was made Eor seeded abalone, during each trial, that

extended out to approximately 15 m from each site reference

point. This general survey focused on ''optimum'' abalone

habitat areas.

RESULTS

Seeding Module Performance

The seeding module performed well during the laboratory

and field trials. Door release mechanisms (magnesium links)

separated as planned, and the buoys lifted the doors clear of

the module passageways on all trials. Also, the

configuration and weight of the module enabled it to remain

stable at the relatively shallow depth of the study site,

even during moderately strong surge conditions. Water

circulation and dissolved oxygen levels were apparently

adequate in the module since there were no abalone

mortalities or evidence of stressed abalone. The grate

affixed to the door passageways was sufficient to preclude

observed abalone predators, yet there was no evidence that

the grates inhibited abalone egress from the module. During

field trials bat stars, Patiria miniata, a scavenger feeder,

were frequently observed on the seeding module, occasionally

attached to a closed door, and also just outside the door

passageways following door release, but none gained entry nor

did they impede door release.

The abalone collector-transporter proved to be an

efficient method for translocating abalone to the seeding

module. Abalone readily crawled on the collector-transporter

When it was placed in a laboratory tank containing abalone,

and there were no mortalities during the two hour transit

(out-of-water) period, for the field trials.

17

18

One diver was able to attach the doors by

interconnecting the magnesium link, place the

collector-transporter (with 500 abalone) in the seeding

module, and connect the buoys in a span of about 5 minutes

with a minimum of disturbance at the site.

Laboratory Trials

Initial Trial Series: Fifty percent of both abalone

size groups (10 mm and 20 mm) had left the seeding module

following two nocturnal periods (Table 2). This percentage

held for all abalone size groups and comparable trials.

Additionally, a direct relationship was evident between

abalone size and dispersal rate from the seeding module. For

example, after 2 days at liberty 80% of the 20 mm abalone

outside of the module were at the perimeter of the tank, in

comparison to only 5% of the lG mm abalone at the tank

perimeter. Moreover, the largest abalone size group (x=32

mm) traveled further and faster, than other size groups (i.e.

91% were at the tank perimeter after two days post-door

release) The smallest abalone size group (x=lG mm)

dispersed more slowly, and initially remained close to the

seeding-module passageways.

The hollow concrete blocks with giant kelp were the

preferred habitat of the two larger abalone size groups

(Table 3). Observations of the largest size group revealed

that following two nocturnal periods post-door-release, 281

(50.7%) of these were outside the seeding module, of which

19

143 (50.9%) were observed on the concrete blocks with kelp,

while only 10 (3.6%) were observed on the concrete blocks

without kelp. This preference of the larger size abalone for

concrete block habitats with giant kelp increased with time.

By contrast, the smallest abalone size group (x=lO mm) was

not observed on concrete blocks until seven nocturnal periods

had elapsed, and very few were present (Table 3). All

abalone size groups formed clumped distributions,

irrespective of habitat type.

Second Trial Series: Abalone dispersal rates from

the seeding module, during this 28 day test, run in

duplicate, compared closely with the first trial series

through 8 nocturnal periods. Also, no significant difference

was apparent between the duplicate test runs for each size

group (Comparison of simple linear regressions, (0.1 < P <

0.2). Following release of the doors from the seeding module

passageways, the exodus of abalone was initially high, then

leveled and maintained at a uniform rate (Figure 4). After

14 nocturnal periods post-door release approximately 50

abalone remained in the module, but very few were on the

collector-transporter and it was removed. Those abalone that

remained in the seeding module preferred the floor-wall

junctures, close to the module passageways. This behavior

became more pronounced during the last two weeks oE the 28

day tests. Also, it became evident through day-to-day counts

that some abalone that had left the module retur. After

20

28 nocturnal periods both the 10 mm and 20 mm abalone size

groups had traveled about equal distances from the seeding

module (i.e. between 60 and 75 percent of both size groups

outside of the module were at the tank perimeter), were found

in clumped distributions, and preferred concrete block habitats

with kelp.

Observations made three nocturnal periods after the

temporary doors were released, and during daylight and

darkness, revealed a correlation between abalone movement and

photoperiod. Observations were made at midday (12 noon and

bright sun), 1.5 hours before sunset, at sunset, and 45 minutes

later and revealed 2,8,41, and 150 emergent abalone,

respectively. Also, observations made at sunset and later

revealed a high activity level of emergent abalone as they

traversed available substrates.

Field Trials

The first trial was conducted during the summer

(August-September, 1984) period when algal assemblages in

Carmel Bay typically attain maximum seasonal growth (Foster and

Schiel 1985). In contrast, the following two trials were

conducted during the late fall and winter months

(November-February) when storm conditions were prevalent. The

results of four weekly site surveys for each of the three

trials, commencing one week post-seeding module door release,

are presented consecutively, according to site.

21

Seeding module site: During each trial the

collector-transporter, with contained abalone seed, was

placed in the seeding module and no conspicuous abalone

predators were observed. Also, abalone predators were not

observed just prior to, and immediately following temporary

door release. This suggests that the seeding module did not

attract potential abalone predators.

Week 1 Survey: Each trial revealed a high initial

exodus of abalone from the seeding module. After this

initial dispersal period there were never more than 13% of

the 10 mm and 25% of the 20 mm seed abalone remaining inside

of the module (Table 4). Typically, about one-half of those

abalone remaining inside were located on the

collector-transporter. Also, no abalone were found dead

inside of the seeding module and relatively few empty shells

were found outside the module. Shell recoveries were

approximately the same for each trial (Table 5).

Random searches for live abalone dispersed from the

module were made with a minimum of disturbance to the site.

A few small rocks were lifted and examined. Generally, 10-50

seeded abalone were located within the articulated coralline

algae and on rock sides and crevices at various distance from

the module. Limited observations made outside the study area

revealed very few abalone. These were seen in good

Protective, cryptic habitats, and not emergent. On a few

occasions the seeded abalone were found adjacent to native

22

red abalone. No octopuses were caught in the traps.

Week 2 Survey: The first trial (summer) witnessed a

sharp decrease of abalone in the module for both size groups

from the previous week. In contrast, trials 2 and 3 (winter)

showed only a slight decrease in the numbers of abalone

remaining inside of the seeding module (Table 4). The

collector-transporter was always removed during this survey

because relatively few abalone were still utilizing it.

These were removed from the collector-transporter but

deposited inside the module. The removal of the

collector-transporter reduced surface area for attachment,

which probably promoted the exodus of the remaining abalone.

Only one abalone death was recorded during all three trials

(trial-3;1-20 mm). Searches for live seed abalone commonly

revealed clumped distributions of two or more individuals.

These abalone were not emergent, but rather cryptic in rocky

recesses, and difficult to see. No octopuses were caught.

Week 3 Survey: Very few abalone remained inside of

the seeding module (less than 3%) during each survey. A few

empty shells were recovered, in about equal numbers, during

each trial (Table 5). Also, fewer live abalone were noted

than prior surveys. These abalone were generally in the same

areas as observed earlier. No octopuses were caught.

Week 4 Survey: Intensive, destructive surveys were

made during each trial. During trials l and 2 a masking crab,

~· crispatus, a potential predator of juvenile abalone, was

23

noted adjacent to the seeding module. No abalone remained

inside the seeding module (Table 4). Abalone mortalities

were very similar to the earlier surveys.

During trial one a total of 178 live abalone,

comprised of almost a 50:50 size group ratio were located and

marked. Fewer abalone were located and recovered during the

second and third trials, conducted during the winter,

compared to the first (summer) trial (Table 6). For all

three trials approximately 15 percent of the abalone were

found within 0.5 m of the seeding module. Most of the

remaining abalone were evenly distributed out to 3 m from the

module. There apP,eared to be no difference in the distance

traveled by either size group of abalone away from the

module. Cursory surveys beyond the site limits uncovered a

few seed abalone, of both size groups, up to 10 m away from

the module. In general, most abalone were found under rocks

that were 15 em and larger in diameter. Also, most

recovered abalone exhibited recent shell growth (Table 6).

The total number of seed abalone unaccounted for steadily

increased from the first to the third trial. This event may

have been influenced by prevailing inclement weather that

occurred during the second and third trials. The storms

reduced available forage, disrupted protective habitats and

probably increased the dispersion of empty seed shells making

recovery more difficult. Two octopuses, Octopus rubescens,

were caught in traps (diameter=3.8 em), one each during trial

24

2 and 3.

Control Site: During each trial 500 abalone were

planted in crevices within and around the two large boulders

that represented the site reference point. No obvious large

abalone predators were observed while seeding the abalone,

although small crabs (eg. Paguristes spp. and Mimulus spp.)

were commonly seen.

Two days post-abalone seeding several large

potential abalone predators were conspicuous. The number and

type of predators present varied between weel1ly surveys and

trials. some of the more common predators observed, but not

removed, listed in order of sighting frequency were Pisaster

spp., o. koehleri, L. crispatus, K• helianthoides, and~·

marmoratus. Additionally, empty abalone shells were commonly

found (lumped with week 1 totals) during these early surveys.

Significantly more 20 mm empty seed shells were found at the

control site during weekly surveys, for each trial, compared

to the seeding module site (Mann-Whitney test, .Ill< P

<.012). In contrast, even though 7 more empty 11 mm seed

shells were recovered overall at the control site there was

not a significant dif renee between the sites for this size

class. Approximately twenty to sixty percent of the seed

abalone were still attached to the adult abalone shells that

had served as their seeding substrate. Also, cursory

examinations of several smaller rocks that were scattered

between the boulders revealed numerous clumps of seeded

25

abalone, several of which were emergent.

Week l Survey: Careful examination of a few rocks

at various distances away from the two central boulders

disclosed that the majority of seed abalone remained in

clumped distributions adjacent to their original seeding

location. Moreover, nearly one-half of these abalone were

emergent, which is not normal behavior for these size red

abalone. For example red abalone less than 12t1 mm are

generally never emergent (T. Ebert, pers. obser.). All

trials revealed more mortality among 20 mm than 10 mm size

group abalone (Table 5). The empty shells were found near

the two large boulders that marked the site reference point.

During trials 2 and 3 an o. rubescens was caught in a trap

(diameter=3.8 mm).

Week 2 Survey: Some abalone could be observed,

partially or wholly exposed without turning or disturbing

rocks. Seed abalone were not observed more than 0.1 m from

the site reference boulders. More 20 mm than 10 mm size

group empty abalone shells were noted during each trial

(Table 5). No octopuses were caught.

Week 3 Survey: During trial two approximately

fifteen small L. crispatus were observed. Most of these were

seen adjacent to the site reference boulders. Only a few

partially or wholly exposed abalone were noted. Very few lt1

mm size group abalone mortalities were found, but

approximately the same numbers of 20 mm size group empty

26

abalone shells were recovered as during week 2 surveys (Table

5). No octopuses were caught.

Week 4 Survey: Intensive, destructive surveys

were made. These surveys typically yielded a greater number

of empty shells, predominatly from the 20 mm size group, than

prior surveys. The majority of these mortalities were found

in previously concealed locations near the two site reference

boulders.

A total of 107 seeded abalone were marked during

trial one with the majority (76%) from the 20 mm size group.

Fewer live abalone were recovered during the second and third

trials (winter) compared to the first (Table 6). All three

destructive surveys revealed that the majority of recovered

live seed abalone (-90%) were found within 0.2 m of the site

reference boulders. No octopuses were caught.

DISCUSSION

Prior abalone seeding projects in Cali.fornia

generally required several divers who expended considerable

time and effort hand-planting abalones. This resulted in

extensive disturbance at the seeding site, and frequently

attracted abalone predators (Fox and McMullen 1981, Tegner

and Butler 1985). The use of "mother" shell (adult abalone,

scallop or oyster shells) as an attachment surf~ce for seed

abalone did serve to reduce seeding time and effort, and

probably reduced stress on the abalones. Data compiled from

several CDFG Cruise Reports show that an average of 529

abalone were seeded per diver hour (range~200-lG27). In

contrast, using the collector-transporter, seeding module

method 511 abalone were seeded in 5 diver minutes, with a

minimum of site disturbance, and without attracting

predators. Moreover, this seeding rate can be increased

several fold simply by increasing the module size and number

of contained abalones.

The abalone containment period in the seeding

module prior to door release (minimum of 48h) was arrived at

through deductive reasoning and proved satisfactory. It was

hypothesized that this time period was sufficient for the

abalone to acclimate, and because no forage (kelp) was

Pto ·a Vl ed, this would serve to hasten their departure from the

le. Yet this starvation period, based on laboratory

27

28

observations, would not stress them, But, no tests were

performed at shorter or longer durations and it is possible

that some other containment time interval would prove more

optimum. However, there is strong evidence from laboratory

and field observations, and ~einforced by this study, to

indicate that twilight (early evening) is an optimum time for

seeding module door release and abalone dispersal. The

abalone activity level sharply increases at this time, and

apparently (based on laboratory observations over several

years), does not diminish until just before dawn. At this

time the abalone seek shelter.

Initially poor water circulation within the seeding

module was a concern, particularly during laboratory trials,

where water flow rates were considered minimal. However,

there was no evidence of anoxic conditions (stressed or dead

abalone) and it became evident that the seeding module could

accommodate a greater abalone density. This was later

confirmed by routinely holding 1000 abalone (both the red and

pink species), averaging about 20 mm long, in a seeding

module on a collector-transporter. These were 48h tests,

performed in the laboratory, and without any abalone

mortalities.

Fox and McMullen (1981) reported that potential

abalone predators were attracted to the seeding area while

the abalones were being seeded, and o'bserved predation of

just-seeded abalones. Tegner and Butler (1985) noted that

29

abalone predators rapidly returned to an abalone seeding area

following their removal, and that seeded and hence stressed

abalones, were vulnerable to the scavengous feeding whelk;

Kellettia. This whelk does not prey on healthy abalone. It

was clearly evident from fie~d observations that there were

more predators at the control site; however, it was not

determined if this was a characteristic of the site or caused

by the presence of abalone. Moreover, the broken abalone

shells recovered at this site probably resulted from

predation by the commonly observed crab, L. crispatus.

Weekly observations indicated that abalone were dispersing

more slowly at the control site than at the module site.

These general observations were confirmed by the final site

surveys (week 4). For example, approximately 90% of the

control site abalone remained within 0.2 rn of the reference

boulders, compared to about 15% of the seeding module abalone

still located within 0.5 m of the module. Because the

control site reference boulders offered reasonably good

abalone habitat this may have retarded their dispersal. Or,

their retarded dispersal rate could have been stress-induced.

Excluding trials two and three (10 mm size group) in which

only two abalone were found, more abalone at the seeding

module site exhibited growth than at the control site when

similar abalone sizes and trials are directly compared

(t-test, .05 > P >.025). It was encouraging to observe that

the seeding module did not attract potential abalone

30

predators, or other reef fauna during the field trial; either

before or after door release. The presence of the omnivorous

bat star,~· miniata, was not unexpected on or proximal to

the seeding module, and did not pose any problems (i.e. door

removal or predation). Although no abalone mortalities could

be directly attributed to octopus predation (drilled shells)

octopuses may have preyed on seeded abalone. Laboratory

studies showed that hatchery-reared and native red abalone,

up to approximately 20 mm in length, can be detached from the

substrate and preyed on by octopuses without being drilled

(T. Ebert, unpubl.data.). Tegner and Butler (1985) noted

that octopuses can severely limit seeding succes if they are

common in the seeding area. Only four o. rubescens were

caught during this study, but the type of octopus trap used

is thought to be effective. Apparently octopus populations

in the area were at low levels, at least during the study

period. This is supported by general and detailed surveys

whereby only one non-trap caught octopus was seen.

Therefore, the use of octopus traps in conjunction with

abalone seeding projects, especially where Octopus spp. are

abundant, is recommended. The adjustable grates, affixed to

the seeding module passageways apparently do serve as

effective barriers to large abalone predators, but would not

restrict octopuses. It is advisable to have the grate size

adjusted such that the spaces between the partitions are

approximately 50 percent wider than the widest abalone.

31

Smaller grates could inhibit abalone egress because the

abalone tend to clump on the grates prior to door release.

The more rapid egress and dispersal of the larger

size group (21 mm) abalone from the seeding module during

laboratory trials and their preference for concrete blocks

with kelp was not unexpected. Momma et al. (1981) and

Miyamoto et al. (1982) also reported that larg•r seed sizes

dispersed more rapidly. Laboratory studies noted a direct

relationship between abalone size and speed (Table 7). The

20 rom size group abalone probably were attracted to the

blocks with kelp because this size abalone prefers

macroalgae, and most likely were more starved than their

smaller size cohorts. Abalones less than 15 mm long prefer a

diatom diet, and diatom films covered most exposed surfaces.

!n view of the above, more 10 rom than 21 mm size group

abalone were expected in the seeding module, through 2 weeks

post-door release, during the field trials. But, this was

not the case. Either those 20 mm size group abalone

remaining subsisted on diatoms (which is quite possible), or

they foraged nocturnally outside the module, but returned,

and used the module for a habitat. But, more significantly,

approximately 50 percent of all abalone had left the seeding

module following two nocturnal periods during the laboratory

trials. Presumably they dispersed at the same rate during

the field trials. The initial surveys at the field site were

made l week post-door-release and only 11-18 percent of the

32

abalone remained in the seeding module. The results of all

laboratory and field trials showed that at least ~6 percent

of all abalone had left the seeding module within 2 weeks.

Two abalone size groups were tested to compare

dispersal rates from the seeding module and survival.

Underlying these tests was the obvious and direct implication

to the economics of seeding abalone for fishery enhancement

i.e., cost effectiveness. It requires about 6 months to

cultivate red abalone to 10 mm shell lengths, and another 5

months for them to attain 20 mm lengths. Hence, the obvious

direct relationship between seed size and cost. The main

objective then is to optimize abalone seed size with

survivorship. Some studies indicate that better abalone

survival is obtained at larger seed sizes (Inoue 1976, Momma

et al. 1980, Miyamoto et al. 1982). But, Tateishi et al.

(1978) showed that good survival can be obtained with smaller

seed sizes (10-16 mm) when protective habitat is available.

Also, Schmitt and Connell (1982) monitored a population of

seeded red abalone (10-45 mm) for 17 weeks and found an

inverse relationship between size and survivorship, and

Tegner and Butler (1985) reported no difference in

survivorship, after 1 year, for two size groups of red

abalone that averaged 45 and 71 mm when seeded. Field

studies at both study sites revealed that for each trial more

of the larger (20 mm) size group abalone were recovered

alive. However, a greater number of 20 mm than 10 mm empty

33

shells were located overall, which might indicate that the

smaller abalone were harder to locate. But, neither of these

two findings can be assumed to accurately reflect the results

because in all trials over 62 percent of the abalone were not

found. I surmise, as did Tegner and Butler (1985), that most

of the unaccounted abalone had dispersed from the study area.

A high percentage of ''unaccounted'' for abalones has

plagued the interpretation of results of most seeding

projects in California. Live abalones less than 20 mm long

are cryptic and frequently not viewable. Moreover, red

abalone are generally not emergent until they attain 120 mm

lengths and 4 or more years of age. This tends to compound

the problem of monitoring a seeded abalone population. But,

empty shells are rather easily seen because their nacreous

interior is reflective and often exposed. Also, they are not

subject to extensive transport by prevailing currents (T.

Ebert unpubl. data, Hines and Pearse 1982, Schmitt and

Connell 1982), Therefore, at least in theory, empty shell

recoveries should serve to estimate seeding success. Using

this criterion, the seeding success, after 4 weeks, ranged

from 95.0-98.4% at the seeding module and 89.0-92.6% at the

control site.

The clumped abalone distribution observed during

the laboratory and field trials is a normal behavioral trait

frequently observed in natural populations, and probably

reflects the dynamics of abalone populations. Stephensen

34

(1924) noted that the abalone H. tuberculata occurs in

.colonies and that they choose localities with "some

exactness.• Stephensen (1924) also reported that H.

tuberculata was relatively mobile and could travel 5-6

m/min. Momma and Sato (1969) observed that H. discus hannai

moved 12.6 m in one hour, and 56.2 m during one night of

foraging. More recently, Hines and Pearse (1982) and Tegner

and Butler (1985) suggest that red abalone populations are

highly dynamic. Findings from this study concur. Laboratory

tank observations, made at night, show that abalones may

traverse the same substrates and habitats, several times in

one night. But, when they locate on optimum habitat they

tend to aggregate (clump). This behavior is not always size

specific, i.e., occasionally a larger abalone (60-B~ mm) will

have several smaller (20-30 mm) abalone clustered around it.

But, generally abalone seek habitats (crevices or beneath

ledges, cobbles or boulders) that will just barely

accommodate them. Therefore, abalone habitat selection

becomes of paramount importance in seeding programs. Habitat

that will support small-size abalone may be lacking for

larger size abalone. Larger size abalone may not require

protective niches, but they do require smooth surfaces.

Siltstone-mudstone substrates often are subject to extensive

bar by pholad clams and support few adult abalones, but

may provide ideal habitat for juveniles. Moreover, in areas

Where currents are sluggish the physical relief must be

35

oriented on a plane other than horizontal {preferably

vertical or the ceiling of overhangs) in order for the

abalones to facilitate waste removal through their

respiratory pores (E. Ebert, pers. comm.).

Seasonality may be another important factor that

predicates the success or failure of an abalone seeding

endeavor. Apparently, however, scant attention has~ been

given to this factor, at least in California. Leighton and

Boolootian (1963) noted a seasonal variation in the growth

rate of black abalone, ~· cracherodii, populations and

attributed it to food supply. The first field trial was

conducted during the August-September period when the flora

typically attains maximum seasonal lushness along the central

California coast {Foster and Schiel 1985). The seafloor

algal "mat" was relatively dense, and correspondingly offered

additional protective habitat for small-size abalone, and an

abundance of food. The second and third field trials were

conducted during winter (November-February) when this algal

"mat'' is typically reduced, consisting principally of

crustose and articulated coralline algae. Theoretically,

abalone seeding success should be the greatest during the

summer months when an excess amount of food is available and

their habitat is not disrupted by storm induced water motion.

A direct comparison of summer and winter trials indicates

that the summer trial had significantly more recovered live

abalone after four weeks at liberty (Mann-Whitney test,

36

.01 < P <.02). Additionally, the vast majority of abalone

released from the seeding module during the summer exhibited

excellent growth and based on general observations appeared

to acclimate quicker and better to their new environment,

unlike the abalone released at the control site and during

the winter months when forage was lacking.

Efforts to enhance California's abalone

populations, either by transplanting mature adult stocl<, or

by seeding smaller size, hatchery-reared abalone, have

spanned a 30 year period. But, the benefits of either method

have been difficult to assess. The transplant method

generally employs a relatively small number of large-size

abalone which are ready to spawn, presumably do so, and the

success of the transplant may be dependent not upon

longer-term adult survivorship, but dispersal and

survivorship of their offspring. Adult transplants are done

at the ''expense" of one region of the fishery to enhance

another. This practice may not be prudent given that the

fishery is being fully-exploited. Conversely, field studies

(Giorgi and DeMartini 1977), and laboratory studies (Ebert

and Houk 1984) show that the onset of sexual maturity in the

red abalone occurs at about a 40 mm shell length. Based on

recovered abalone seed shell growth increments, 19 mm abalone

take about a year and a half in the wild to reach sexual

maturity, while 2~ mm size individuals require a little less

than one year. Additionally, these smaller size red abalone

37

exhibit unusual sexual vigor in the laboratory, when compared

to larger adults, and may spawn three times annually (Ebert

and Houk 1984). Presumably this occurs in nature and may

serve to enhance recruitment through broadcasting gametes

during most or all annual oceanographic regimes. Hence,

contribution of the seed abalone to the resource begins when

they attain sexual maturity and contribute to the population

reproductively, rather than upon attainment of the sport or

commercial legal size.

Also, laboratory observations made over several

years indicate that hatchery-reared abalone respond similarly

to their natural population cohorts with respect to

predator-prey relationships (T. Ebert, unpubl. data, Schiel

and Weldon, manuscript in review). For these reasons it is

suggested that hatchery-reared abalones be seeded in future

programs rather than the transplantation of adults. The red,

green, and pink abalone species are routinely cultivated, and

available.

The results of this study suggest that the use of

an abalone collector-transporter, seeding module method

offers:

1) An efficient method to collect, transport and seed relatively large numbers of abalone.

2) Reduced handling stress on abalone.

3) An acclimation period for abalone free from potential predators.

4) A timed-release mechanism that permits abalone dispersal at an optimum time.

38

Further research is needed on optimizing abalone

seed size and survivorship, and the development of a reliable

method to assess the results of a seeding program.

LITERATURE CITED

Burge, R., s. Schultz and M. Odemar. 1975. Draft report on recent abalone research in California with recommendations for management. State of California. The Resources Agency, Depart. Fish and Game. 62pp.

Burge, R. T, and s. A. Schultz. 1973. The marine. environment in the vacinity of Diablo Cove with special reference"to abalones and bony fishes. Mar. Res. Tech. Report No. 19. 433p.

Cicin-Sain, B., P. M. Grifman, and J, B. Richards. 1982. Social science perspectives on managing conflicts between marine mammals and fisheries. University of California Cooperative Extention, San Luis Obispo. 347 p.

Cox, K. w. 1962. California abalones, family Haliotidae. (118) 1-133.

Calif. Dept. Fish and Game, Fish Bull.

Ebert, E. E. 1968a. California sea otter-census and habitat survey. Underwater Naturalist, Winter:20-23

1968b. A food habits study otter, Enhydra lutris nereis. Game, 54(1):33-42.

of the southern Calif. Fish and

Ebert, E. E. and J. L. Houk. 1984. Elements and innovations in the cultivation of red abalone

l rufescens. Aquaculture, 39:375-392,

sea

Foster, M. s., and D. R. Schiel. 1985. The ecology of giant kelp forests in California: a community profile. u.s. Fish and Wildl. Serv. Biol. Rep.85(7.2): 152 p.

Giorgi, A. E. and J. D. DeMartini. 1977. A study of the reproductive biology of the red abalone, Haliotis rufescens Swainson, near Mendocino, California. Calif. Fish and Game, 63(2):80-94.

Hardy, R. F. Wendell and J. D. DeMartini. 1982. A status report on California shellfish fisheries. Pages 328-340 in B. Cicin-Sain, P.M. Grifman and J, B. Richards, eds, Social science perspectives on managing conflicts between marine mammals and fisheries.

Hines, A. H. and J. s, Pearse. 1982. Abalones, shells and sea otters: dynamics of prey populations in central California. Ecology, 63(5):1547-1560.

39

40

Ina, T. 1966. [The abalone science and its propagation in Japan), Pages 2-105 in Vol. No. 11 in the series on the propagation of the marine products. Published by the Japan Fisheries Resource Conservation Association. Fisheries Research Board of Canada, Translation Series No. 1078.

Inoue, M. 1976. [Abalone.] Pages 19-60 in Suisan Zoyoshoku Deeta Bukku. [Fisheries Propagation Data Book.) Published by Suisan Shupoan. Translation by !'1. Mottet, State o"f Washington,· Def?artment of Fisheries.

Kan-no, H. 1975. Recent advances in abalone culture in Japan. Pages 195-211 in Proc. first international conference on aquaculture nutrition, Sea Grant Program at the Univ. of Delaware.

Leighton, D. L. 1961. Observations of the effect of diet on shell coloration in the red abalone, Haliotis rufescens Swainson. The Veliger 4(1):29-32.

Leighton, D. L. and R. A. Boolootian. 1963. Diet and growth in the black abalone, Haliotis cracherodii. Ecology, 44(2):227-238.

Miller, D. J. 1974. The Sea Otter Enhydra lutris: Its Life History, Taxonomic Status, and Some Ecological Relationships. Calif. Dept. Fish and Game, Mar, Res. Leafl. (7):1-13.

Miyamoto, T., K. Saito, s. Mataya, and K. Kawamura. 1982. Experimental studies on the release of the cultured seeds of abalone, Haliotis discus hannai Ina in Oshoro Bay, Hokkaido. Sci Repts. Hokkaido Fisheries Experimental Station, No. 24:59-89. (English abstract, figures and tables).

Momma, H. and R. Sato. 1969. The locomotion of the disk abalone, H. discus hannai Ina, and the Seibold's abalone H. seiboldii Reeve in the fishing grounds. Tohoku J Agric Research 20 (3): 150-157

Momma, H., K. Kobayashi, T. Kato, Y. Sasaki, 'r. Sakamoto, and H. Murata. 1980. [On the artificial propagation method of abalone and its effects on rocky shores. I. Remaining ratio of the artificial seed abalone (Haliotis discus hannai Ina) on latticed artificial reefs.] Suisan Zoshoku [The Aquaculture], 28 (2):59-65. Translation by M. Mottet, State of Washington,Department of Fisheries.

41

Mottet, M. 1978. A review of the fishery biology of abalones. State of Washington, Department of Fisheries, Technical Report No. 37:1-81.

Mottet, M. 1981. Enhancement of the marine environment for fisheries and aquaculture in Japan. State of Washington, Department of Fisheries, Technical Report No. 69:1-176.

Olsen, D. A. 1968. Banding patterns in Haliotis. II. Some behavioral considerations and the effect of diet on shell coloration for Haliotis rufescens, H. corrugata, ~ sorenseni and H. assimilis. Veliger-11 (2): 135-139.

Owen, B., J. H. McLean and R. J. Meyers. 1971. Hybridization in the eastern Pacific abalones (Haliotis). Los Angeles Co. Mus. Nat. Hist., Sci. Ser. 9, 37p.

Schiel, D. R. and B. A. Welden. Manuscript in review. Responses to predators of cultured and wild red abalone, Haliotis rufescens, in laboratory experiments.

Schmitt, R. J. and J. evaluation of an Pages 172-176 in Program 198~-1982 Marine Resources, Jolla.

H. Connell. 1981. Field abalone enhancement program. California Sea Grant College Biennial Report, Institute of University of California, La

Schultz, S. A. 1984. Status of abalone resource. Odyssey, 7 (2):4-5.

Stephenson, T. A. 1924. Notes on Haliotis tuberculata. J. Mar. Biol. Assoc. 13 (2): 480-495.

Tateishi, M., M. Tashiro, and T. Yada. 1978. Place of releasing and survival rate of artificially raised young abalone, Haliotis discus. Suisan Zoshoko [The Aquaculture], 26(1):1-5. Translation by M. Mottet, State of Washington, Department of Fisheries.

Tegner, M. J., J. H. Connell, R. W. Day, R. J. Schmitt, S. Schroeter, and J. B. Richards. 1981. Experimental abalone enhancement program. Pages 114-116 in California Sea Grant College Program 1978-198~ Biennial Report, Institute of Marine Resources, University of California, La Jolla.

Tegner, M. J. and R. A. Butler. 1985. The survival and mortality of seeded and native red abalones, Haliotis rufescens, on the Palos Verdes Peninsula. Calif. Fish and Game, 71(3):15~-163.

-- Abalone transplants and seeding efforts in California, exclusive of seeded in private enterprise leased sites, 1956-86,

Date Species Number of Abalone

Transplanted Seeded

2/56 H~ rufescens

4/56 H, cracherodii

4/56 H, cracherodii

3/57 H, corrugata

8/5 7 H. rufe s cens

10/58 H, corrugata

4/67 H~ rufescens

H. cracherodii

H, corrugata

6/69 H. rufescens

800

358

351

380

52

300

58

4

1760

500

Abalone Size

adults

adults

adults

adults

adults

adults

12-15 rnrn

adults

adults

adults

Capture Location

Planted/Seeded

San "t-liguel Is.

White Pt, Palos Verdes Peninsula

Santa Catalina Is,

Santa Catalina Is.

Santa Catalina Is, \>lhi te Pt. Palos Verdes Peninsula

Santa Catalina Is, (\-.rest end)

Pt. Estero, San Luis Obispo Co,

Santa Catalina Is, (west end)

Guadalupe Is., Hexico

Diablo Cove, San Luis Obispo Co,

Santa Catalina Is (A':alon Harbor)

Pacific Grove, Nonterey Co,

Santa Catalina Is, (Avalon Harbor)

Pt. Estero, San Luis Obispo Co.

Santa Barbara Co. (Richmond Oil Is,)

Shell Beach and Montano de Oro State Park, San Luis Obispo Co,

_ _-'- continu€d Number of Abalone Abalone Location

Date Sf>ecies TransE lan ted Seeded Size CaEture Planted/Seeded

6/69 !!· crache rodii 1016 adults

7/69 H. rufescens 121 adults Diablo Cove, San Hontano de Oro Luis Obispo Co, State Park, San

Luis Obispo Co,

9/69 !i· rufescens 3993 adults Diablo Cove, San Montano de Oro Luis Obispo Co, State Park, San

Luis Obispo Co.

H. cracherodii 200

3/70 !i· cracherodii 4325 adults Diablo Cove, San :M.ontano de Oro Luis Obispo Co. State Park, San

Luhs Obispo Co.

5/70 !i· cracherodii 2113 adults Diablo Cove, San 1'-!ontano de Oro Luis Obispo Co, State Park and

Sunset Palisades, San Luis Obispo Co.

5/70 H. rufes cens 828 adults Diablo Cove, San San Luis Obispo Co. Luts Obispo Co.

6/70 !i· cracherodii 370 adults Diablo Cove, San Sunset Palisades, Luis Obispo Co. San Luis Obispo Co.

5/72 H. rufescens 740 adults Diablo Cove, San Pt. San Luis, San Luis Obispo Co. Luis Obispo Co. ...

w

5/72 H. rufescens 400 6-14 mm Avila, San Luis Obispo Co.

- -co-n t::in ue d Number of Abalone Abalone Location

Date Species Transplanted Seeded Size Capture Planted/Seeded

11/73 D:· fulgens 310 adults San Clemente Is. Santa Catalina Is. (Isthmus)

6/74 H. rufescens 1000 8-12 nun Abalone Cove, Palos Verdes Peninsula

H. rufescens 1000 24-50 nun

7/75 H. rufescens 15000 10-25 nun Heisler Harine Reserve, Orange Co.

7/75 H. corrugata 375 adults San Clemente Is. Heisler Marine Reserve, Orange Co.

11/75 H. fulgens 325 adults Santa Catalina Is. Heisler Harine Reserve, Orange Co.

11/75 H. fulgens 500 adults Santa Catalina Is. Heisler Harine San Clemente Is. Reserve, Orange Co.

1/76 H. fulgens 325 adults Santa Catalina Is. Heisler Marine Reserve, Orange Co.

9/76 H. fulgens 250 adults Santa Catalina Is. Abalone Cove, Palos Verdes Peninsula

11/76 H. fulgens 350 adults San Clemente Is. Heisler Harine Reserve, Orange Co. "" ....

H. corrugata 109 adults

3/77 H. rufescens 1000 5-10 mm Port Hueneme (harbor en trance), Ventura Co.

-- c'on tin ue d Abalone Location Number of Abalone

Date Species Transplanted Seeded Size Capture Planted/Seeded

6/77 H. rufescens 1000 5-12 mm Bass Rock, Ventura Co.

12/77 !:!_. rufescens 1000 juveniles Johnson's Lee, Santa Rosa Is.

5/78 H. rufescens 500 10-45 mm Bass Rock, Ventura Co.

ll/78 H. rufescens 550 27 mm Lunada Bay, Palos Verdes Peninsula

ll/78 H. rufescens 5000 40 mm Lunada Bay, Palos Verdes Peninsula

ll/78 H. rufescens 5000 25 mm Lunada Bay, Palos Verdes Peninsula

5/79 H. rufescens 69 86 10-75 mm Anacapa Is.

6/79 H. fulgens 109 adults Palos Verdes Peninsula

8/79 H. rufescens 20700 28-34 mm San :Higuel Is.

10/79 H. rufescens 21700 10-22 mm San Miguel Is.

10/79 H. rufescens 300 30-50 mm Anacapa Is. .,. 12/79 H. rufescens 7000 32 Pt. Vincente, Palos

U1 mrn

Verdes Peninsula

12/79 H. corrugata 6()0 39 mm Pt. Vincente, Palos Verdes Peninsula

c-ontinued Number of Abalone Abalone Location

Date Species Transplanted Seeded Size Capture Planted/Seeded

3/80 H. rufescens 3000 25 rrnn Palos Verdes Peninsula

5/80 H. rufescens 9000 10-45 rrnn Naples Reef, Santa Barbara Co.

10/80 H. fulgens 8400 14-40 rrnn Palos Verdes Peninsula

11/80 ,!!. rufescens 10000 13 rrnn Palos Verdes Peninsula

5/81 ,!!. rufescens 501 70 rrnn Palos Verdes Peninsula

5/81 H. rufescens 250 LeO rrnn Pal,os Verdes Peninsula

6/81 H. fulgens 26 adults Palos Verdes Peninsula

6/81 !!· corrugata 14 adults. Palos Verdes Peninsula

8/81 ,!!. fulgens 1000 20 rrnn Santa Cruz Is.

9/81 H. fulgens 19000 20 rrnn Santa Cruz Is.

11/81 H. fulgens 57 adults Santa Barbara Is. Golden Cove, Palos ... Verdes Peninsula "'

12/81 !!· rufescens 19000 13-40 rrnn Pendleton Artificial Reef, Orange Co.

le l. -- cont:inued Number o£ Abalone Abalone Location

Date S[Je cies TransE lanted ·Seeded Size Capture Planted/ Seeded

2/82 H. fulgens 6 75 150 mm Santa Barbara Is. Golden Cove, Palos Verdes Peninsula

4/82 H. ;fulgens 1150 150 U1Ill Santa Barbara Is. Golden Cove, Palos Verdes Peninsula

6/82 H. fulgens 608 adults Santa Barbara Is. Golden Cove, Palos Verdes Peninsula

8/82 H. fulgens 980 150 1Jli!l Santa Barbara Is. Orange Co.

8/82 H. fulgens 1010 150 mm Palos Verdes Peninsula

9/82 H. fulgens 1040 150 rnrn Palos Verdes Peninsula .

9/82 H. fulgens 5000 11-31 rnm Santa Catalina Is.

10/82 H. fulgens 5000 14-42 rnm Santa Catalina Is.

12/82 H. fulgens 9200 15-43 rnm Santa Catalina Is.

1/83 !:J.. corrugata 237 95-170 = San Clemente Is. Sa."'1ta Catalina Is.

4/83 H. corrugata 280 145 rnm S&"'1 CleTIEnte Is. Orange Co.

5/83 H. fulgens 3066 40-75 nun Platt's Harbor, Santa Cruz Is. ...

-J

8/83 !:J.. fu1gens 1045 155 rnm Santa Barbara Is. Orange Co.

12/83 H. rufescens 10000 juveniles Pt. Loma, San Diego Co.

le 1. -- continued Number of Abalone Abalone.

Date Species Transplm<ted Seeded Size

6/84 H. rufescens

8/84 ~· rufe.sce.ns

11/84 H. fulgens

4/85 H. rufescens

5/85 H. rufe.scens

H. rufescens

7/85 H. rufescens

H. rufescens

8/85 H. corrugata

9/85 H. corrugata

H. rufescens

l/86 H. rufescens

4100

10000

800

3000

600

600

900

500

2000

2000

1000

1250

25-65 mm

10-15 mm

2 3 TiliU

juveniles

30-46 unn

36-50 mm

2 7-45 mm

4 7-66 IT!IIl

16-28 TiliU

15-25 unn

44-70 mm

44-54 mm

Capture

>~'Compiled principally from CDFG cruise reports.

Location Planted/Seeded

Pt. Vincente, Palos Verdes Peninsula

Russian Gulch State Park

Pt. Vincente, Palos Verdes Peninsula

Pt. Lorna, San Diego Co.

Abalone Cove, Palos Verdes Peninsula .

Abalone Cove, Palos Verdes Peninsula

Abalone. Cove, Palos Verdes Peninsula

Abalone Cove , Palos Verdes Peninsula

Abalone Cove, Palos Verdes Peninsula

Abalone Cove, Palos Verdes Peninsula

49

Table 2. -- Dispersal rate of red abalone from the seeding module, during laboratory trials, according to size group.

Abalone size Nocturnal periods and abalone (%) group (mm) found outside seeding module

l 2 4 . ; 5 7 8 . 28 28

10 38.4 57. 2 70.4 73.6 72.0 60.8 88.0 92.8

20 52.0 50.2 80.0 59.6 94.0 86.0 92.0 99.2

32 50.7

50

Table 3. -- Nuwber of red abalone observed on concrete block habitats with and without giant kelp.

Abalone size Nocturnal period and no. of abalone group ( nn:n) on habitats (kelp/no kelp)

l 2 .4 5 7 8 . 28 . 28

10 0/0 0/0 0/0 0/0 2/2 2/0 19/9 24/13

20 14/0 20/0 32/6 34/5 65/7 56/6 63/13 89/15

32 143/10

51

Table 4. -- Red abalone fotmd inside of the seeding module during weekly surveys at the field study site in Carmel Bay.

Abalone size group (rum)

lO

20

· Trial

1

2

3

1

2

3

·week

13

31

22

40

61

31

~ Shell ·week

1

23

20

11

45

22

recoveries 2 week 3

4

0

2

4

14

8

(no.) ·week 4

0

0

0

0

0

0

Table 5. -- Empty red abalone seed shells recovered during weekly surveys at the field sites in Canrel Bay,

Abalone size Shell recoveries (no. I condition'~) Site group (mm) Trial week 1 week 2 week 3 '"eek 4

Seeding 10 1 0/-- 0/-- 0/-- 2/1

module 2 5/1 01-- 1/1 3/1

3 2/1 0/-- 1/F 1/F

20 1 2/1 0/-- 1/F 2/1

1/1

2 4/1 0/-- 6/1 4/CE

2/1

3 2/1 l/F 2/F 1/1

1/F

Control 10 1 2/1 3/1 2/1 5/1

2 1/1 2/F 0/-- 0/--

3 1/1 2/1 0/-- 4/1

20 1 2/1 2/1 2/1 5/F

8/F 2/CE 3/CE 8/l

ll/CE

L11

"'

's. -- contin1..Jad

Abalone size Site group (rom) Trial week 1

2 6/1

11/F

3 4/1

6/1

·~<1=intact, F= fragTIEnt, CE= chipped edges

Shell recoveries week 2

5/F

2/1

4/CE

(no, I condition'~') week3 week

3/F 9/F

2/1 3/F

2/F 7/1

8/CE

4

U1 w

Table 6, -- Live red abalone recovered, percent shotdng shell growth, and percent unaccounted for, after four weeks, from the field study sites in Carmel Bay,

Abalone size Live abalone New shell Abalone Site group (mm) Trial no, fo gra"~<7th tmaccotm ted (/.)

Seeding 10 1 87 34,8 94,3 64,4

module 2 21 8.4 93.5 88.0

3 3 1.2 100 97.2

20 l 91 36 '4 99.6 61.2

2 39 15.6 87,2 78.0

3 26 10,4 61.5 86.8

Control lO l 26 10.4 36.4 84.8

2 2 0.8 100 98.0

3 2 0,8 100 96.4

20 1 81 32.4 84.0 50.4

2 55 22,0 69.1 64.4

3 46 18.4 43.5 65.6

( li"

r: t:

U1 .,.

55

Table 7, -- Locomotory rates for three size groups of

hatchery-reared red abalone on plastic laboratory tank

surfaces,

Abalone size group (mm) -1, Speed (em/min,)

10 17,0 + 4.2

20 30 0 7 + 6,3

30 38,7 + 7 .lf' ·k D"'20 of each size group

BASt:: ,. "'l. c-ure 1 Lo ,

..__Buoys---.. 'fp.J

LiFTtN G Loops--._

L!o

temporary door interior

- The ~-abalone seeding modulo ASTRoTURF MAGNESIUM

LiN/( _lATEX TUatNc ·- With cut-away sect:z.· L •

. on Suow:z.ng the NJ..th astroturf and the .

PART! TtoN

ma&nesl. um link attachment, 01 0\

Figure 2, - The collector-transporter used for translocating abalones from the

laboratory to the field, Not to scale, Dimensions, overall, are 50 em by 31 em

by 19 em high,

CONCRETE

BLOCK

HABITATS

SAND

WjOUT KELP

W/ OUT KELP

SEEDING

MODULE

58

C ONC,R E'T E

BLOCK

HABITATS

0 SAND

Figure 3. - A schematic diagram of the 2. 3 m diameter tank

floor layout used to measure abalone dispersal rates and

patterns.

250

w --' ::J 200 0 0 :2:

z 150

w z 0 --' 100 <t co <t

lL

0 50 c:i z

0

I I I I I I I I I I \0

I

• 0 •

----0 0

- " 10mm size group --- o 2.0mm size group

• • • rJ'

• 'l. 0 --- 0 • - ----0 0 - -9---.o--- A

0 0 0 - -"t-- ....Sb

• • • •

NOCTURNAL PERIODS

Figure 4, - Dispersal rate of the red abalone from the seeding module during

laboratory trials,

Ul UJ