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Facts About Abalone
WORLD SUPPLY OF ABALONE FROM ALL SOURCES
the animal kingdom, abalone belong to the phylum Mollusca, a group which
includes clams, scallops, sea slugs, octopuses and squid. Mollusks are
world wide and predominantly marine. They have a soft body surrounded by
a mantle, an anterior head and a large muscular foot. Mollusks are best
known for their beautifully formed and colored calcareous shell secreted
by the mantle.
The abalone join other snails, whelks and sea slugs in the class Gastropoda.
Members of this class have one shell, as opposed to clams with two, (or
the shell may be lacking altogether, as in the sea slugs). The spiral
structure, so common in snail shells, is flattened in the abalone and
may be obscured by fouling and shell boring organisms. Abalone are
members of the family Haliotidae and the genus haliotis, which means sea
ear, referring to the flattened shape of the shell. The name abalone is
probably derived from the Spanish-American word aulon or aulone.
The most conspicuous part of any abalone is the shell, with its row of
respiratory pores. Shells are prized because of their inner, iridescent
layer. The muscular foot has a strong suction power permitting the
abalone to clamp tightly to rocky surfaces. A column of shell muscle
attaches the body to its shell. The mantle circles the foot as does the
epipodium, a sensory structure and extension of the foot which bears
tentacles. The epipodium projects beyond the shell edge in the living
animal. The epipodium surface may be smooth or pebbly in appearance and
its edge may be frilly or scalloped. It is the most reliable structure
for identifying abalone species.
Anatomy of an Abalone with Shell Removed
The internal organs are arranged around the foot and under the shell. The
most conspicuous organ, the crescent-shaped gonad, is gray or green in
females and cream colored in males. It extends around the side opposite
the pores and to the rear of the abalone. The abalone has a pair of
eyes, a mouth and an enlarged pair of tentacles. Inside the mouth is a
long, file-like tongue called the radula, which scrapes algal matter to
a size that can be ingested.
The gill chamber is next to the mouth and under the respiratory pores. Water
is drawn in under the edge of the shell, and then flows over the gills
and out the pores. Waste and reproductive products are carried out in
the flow of water. Since it has no obvious brain structure, the abalone
is considered to be a primitive animal. However, it does have a heart on
its left side and blood flows through the arteries, sinuses and veins,
assisted by the surrounding tissues and muscles.
Abalone Life Cycle
Commercial Abalone Species
FISHTECH INC. works with the following species:
FISHTECH INC. works with 14 different species of abalone worldwide.
Click on the link to read some information about Red Abalone.
The sexes are separate and can be distinguished in individuals as small as one
inch when the gonads begin to develop. The eggs or sperm are released
through the pores with the respiratory current. This is known as broadcast
spawning. A 1.5 inch abalone may spawn 10,000 eggs or more at a time, while
an 8 inch abalone may spawn 11 million or more. Spawning may be controlled
by the water temperature or length of the day. The presence of eggs and
sperm in the water may stimulate other abalone to spawn, thus increasing the
chances of fertilization.
The egg hatches as a microscopic, free living larvae. It drifts with the
currents for about a week, then the abalone larvae settles to the bottom,
sheds its swimming hairs (cilia) and begins to develop the adult shell form.
If suitable habitat is located it may grow to adulthood. the chance that an
individual larva will survive to adulthood is very low. Fortunately abalone
and most mollusks are prolific spawners but the mortality still probably
Hybrid abalone are not uncommon in areas where several species occur together. All
species can hybridize, but the most common hybrids are red and white with
Abalone eat marine algae in the wild and on some farms. The adults feed on loose
pieces drifting with the surge or current. Large brown algae such as giant
kelp, bull kelp, feather boa kelp and elk kelp are preferred, although most
others may be eaten at various times. For cultured abalone, many farms now
use high quality manufactured food, which is healthy, efficient and produces
very high quality meat.
Wild abalone tend to stay in one location waiting for food to drift by. However,
they will move daily, seasonally or when food becomes scarce for a long
period. The color banding on many abalone shells is due to changes in the
types of algae eaten. Juvenile abalone graze on rock encrusting coralline
algae and on diatoms and bacterial films. As they grow they increasingly
rely on drift algae.
Abalone farming, to date, has been limited and hampered by the quality and quantity
of the macroalgae sources worldwide. Although some abalone farms have successfully fed manufactured
food for nearly 25 years, a high quality low cost manufactured food has been
a recent development. Many new farms (and some older farms) are now asking
Fishtech to design or redesign their equipment and procedures to allow their crop to be grown on 100% manufactured
food. The improvement in growth rate and health of the animals and ease of production are truly
Predators in the wild:
Throughout its life, an abalone contends with a variety of predators. The eggs and
larvae are eaten by filter-feeding animals. Though juvenile abalone hide,
they are active at night (nocturnal) and crabs, lobsters, octopuses,
starfish, fish and predatory snails prey on them. Abalone in shallow water
may be crushed by storm tossed rocks.
Large abalone are not threatened by the predators of their earlier life, but
larger, and often more efficient predators now become important. Fishes,
such as the cabezon, can dislodge some abalone and swallow them whole. Even
very large abalone are no match for the crushing jaws of a bat ray. The sea
otter is the most effective predator, capable of removing all exposed
abalone within reach. Only those in deep crevices or under large rocks will
survive. Abalone are one of the first food items taken by otters as they
move into new habitat.
In the last 20+ years, the commercial catch of
abalone worldwide has declined from 18,000mt to a little over 10,000mt. Below
are listed 6 major reasons for the decline. Number 5 (Illegal harvesting) is
by far the largest and most important reason for the decline.
Predation. Sea otters (major abalone predators) expanded their range in central
California virtually eliminating recreational and commercial fisheries
for abalone and other invertebrates. Commercial abalone harvesting is
now primarily concentrated in southern California.
Mortality of small abalone for many reasons.
Over harvesting. Abalone are easily over harvested because of slow growth and
variable reproductive success. Initial high harvests cannot be
Competition. Sea urchins and other species, utilizing abalone food and living space.
Illegal harvesting. Some people ignore the regulations enacted to protect
abalone because abalone bring high prices.
- Loss of habitat. Coastal "development" and pollution have ruined
large areas of abalone habitat.
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