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 TABLE OF CONTENTS
Page
ABSTRACT, • • • iii
LIST OF TABLES .. v LIST OF FIGURES vi ACKNOWLEDGEMENTS vii
INTRODUCTION 1
METHODS AND MATERIALS 8
Abalone Seeding Module Design and Operation 8
Abalone Collector-Transporter 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 •• 20
Seeding Module Site. 21
Control Site 24
DISCUSSION. 27
LITERATURE CITED. 39
TABLES. 42
FIGURES • • 56 iv LIST OF TABLES
Table Page
1. Abalone tLansplants and seeding efforts in
CalifoLnia, exclusive of abalones seeded
in private enterpLise leased sites,l956-B6. • 42
2. Laboratory dispersal Late of Led abalone from
the seeding module. • • . ••••• • 49
3. Number of red abalone observed on concrete block
habitats with and without giant kelp •••• • 50
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
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. . • • • • ...... 52 6. Live red abalone recovered, percent showing shell
growth, and percent unaccounted for, after
four weeks from the field study sites in 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. • 56
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. .. .. • 57
3. A schematic diagram of the 2.3 m diameter tank
floor layout used to measure abalone
dispersal rates and patterns • .. 58
4. Dispersal rate of the red abalone from the
seeding module during laboratory trials. • .. • 59
vi 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 13 duplicated using two "fresh" abalone size groups.
Field Studies
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 Vl·a 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. Calif. Dept. Fish and Game, Fish Bull. (118) 1-133.
Ebert, E. E. 1968a. California sea otter-census and habitat survey. Underwater Naturalist, Winter:20-23
1968b. A food habits study of the southern sea otter, Enhydra lutris nereis. Calif. Fish and Game, 54(1):33-42.
Ebert, E. E. and J. L. Houk. 1984. Elements and innovations in the cultivation of red abalone l rufescens. Aquaculture, 39:375-392,
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. H. Connell. 1981. Field evaluation of an abalone enhancement program. Pages 172-176 in California Sea Grant College Program 198~-1982 Biennial Report, Institute of Marine Resources, University of California, La Jolla.
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,
Number of Abalone Abalone Location Date Species Transplanted Seeded Size Capture Planted/Seeded
2/56 H~ rufescens 800 adults San "t-liguel Is. Santa Catalina Is,
4/56 H, cracherodii 358 adults White Pt, Palos Santa Catalina Is. Verdes Peninsula
4/56 H, cracherodii 351 adults Santa Catalina Is, \>lhi te Pt. Palos Verdes Peninsula
3/57 H, corrugata 380 adults Santa Catalina Is, Santa Catalina Is (\-.rest end) (A':alon Harbor)
8/5 7 H. rufe s cens 52 adults Pt. Estero, San Pacific Grove, Luis Obispo Co, Nonterey Co,
10/58 H, corrugata 300 adults Santa Catalina Is, Santa Catalina Is, (west end) (Avalon Harbor)
4/67 H~ rufescens 500 12-15 rnrn Pt. Estero, San Luis Obispo Co.
H. cracherodii 58 adults Guadalupe Is., Santa Barbara Co. Hexico (Richmond Oil Is,)
H, corrugata 4 adults
6/69 H. rufescens 1760 adults Diablo Cove, San Shell Beach and Luis Obispo Co, 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 -- Number of Abalone Abalone Location 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. .,. U1 12/79 H. rufescens 7000 32 mrn Pt. Vincente, Palos 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. Location Date Species Transplm 8/84 ~· rufe.sce.ns 10000 10-15 mm Russian Gulch State Park 11/84 H. fulgens 800 2 3 TiliU Pt. Vincente, Palos Verdes Peninsula 4/85 H. rufescens 3000 juveniles Pt. Lorna, San Diego Co. 5/85 H. rufe.scens 600 30-46 unn Abalone Cove, Palos Verdes. Peninsula H. rufescens 600 36-50 mm 7/85 H. rufescens 900 2 7-45 mm Abalone Cove, Palos Verdes Peninsula H. rufescens 500 4 7-66 IT!IIl 8/85 H. corrugata 2000 16-28 TiliU Abalone. Cove, Palos Verdes Peninsula 9/85 H. corrugata 2000 15-25 unn Abalone Cove , Palos Verdes Peninsula H. rufescens 1000 44-70 mm Abalone Cove, Palos Verdes Peninsula l/86 H. rufescens 1250 44-54 mm Abalone Cove, Palos Verdes Peninsula >~'Compiled principally from CDFG cruise reports. 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 Shell recoveries (no.) group (rum) · Trial ·week ~ ·week 2 week 3 ·week 4 lO 1 13 1 4 0 2 31 23 0 0 3 22 20 2 0 20 1 40 11 4 0 2 61 45 14 0 3 31 22 8 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 L11 20 1 2/1 2/1 2/1 5/F "' 8/F 2/CE 3/CE 8/l ll/CE 's. -- contin1..Jad Abalone size Shell recoveries (no, I condition'~') Site group (rom) Trial week 1 week 2 week3 week 4 2 6/1 5/F 3/F 9/F 11/F 3 4/1 2/1 2/1 3/F 6/1 4/CE 2/F 7/1 8/CE ·~<1=intact, F= fragTIEnt, CE= chipped edges 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 li" r: 20 l 91 36 '4 99.6 61.2 t: 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 .,.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 ..__Buoys---.. 'fp.J LiFTtN G Loops--._ L!o ,. BASt:: "'l. Loc-ure 1, - The ~- ASTRoTURF temporary door interiorabalone seeding modulo MAGNESIUM LiN/( _lATEX PART! TtoN TUatNc NJ..th astroturf·- andWith the cut-away .sect:z.· L • . on Suow:z.ng the 01 ma&nesl. um link attachment, 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, 58 C ONC,R E'T E W/ OUT KELP BLOCK HABITATS SEEDING MODULE SAND 0 SAND CONCRETE BLOCK HABITATS WjOUT KELP Figure 3. - A schematic diagram of the 2. 3 m diameter tank floor layout used to measure abalone dispersal rates and patterns. 250 w --' - " 10mm size group ::J 200 I 0 I --- o 2.0mm size group 0 I :2: I I z 150 I I w I z I 0 I --' 100 \0 NOCTURNAL PERIODS Ul UJ Figure 4, - Dispersal rate of the red abalone from the seeding module during laboratory trials,