California Spiny Lobster - Status of Biological Knowledge -- X-LOBSTERMAN'S MESSAGE BOARD

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Date Posted: 02:59:24 10/15/02 Tue
Author: Randall
Author Host/IP: 142.177.75.102
Subject: California Spiny Lobster - Status of Biological Knowledge

Status of Biological Knowledge

The California spiny lobster ranges from Monterey Bay,
California to Manzanillo, Mexico. There is also a small,
isolated population of this species at the northwestern
end of the Gulf of California. The majority of the pop-
ulation is found between Point Conception, California
and Magdalena Bay, Baja California. Adult lobsters usually
inhabit rocky areas from the intertidal zone to depths of
240 feet or more.

Spiny lobsters mate from November through May. The
male attaches a putty-like packet of sperm, called a sper-
matophore, to the underside of the female �s carapace.
When the female releases her eggs, she uses the small
claws at the end of her last (fifth) pair of walking legs to
open the spermatophore and fertilize the eggs with the
sperm inside the packet. Fertilized eggs are attached to
the underside of the female�s tail primarily in May and
June. �Berried � females are generally in water less than
30 feet deep and carry their eggs for about 10 weeks. The
larger the size of the female, the more eggs she produces.
Females sampled at San Clemente Island carried between
120,000 (2.6 inches CL) and 680,000 (3.6 inches CL) eggs.
Spiny lobster eggs hatch into tiny, transparent larvae
known as phyllosomas that go through 12 molts. They have
flattened bodies and spider like legs,and drift with the
prevailing currents feeding on other planktonic animals.
They may drift offshore out to 350 miles, and may be
found from the surface to a depth of over 400 feet. After
five to nine months, the phyllosoma transforms into the
puerulus or juvenile stage. The puerulus is still transpar-
ent, but now looks like a miniature adult with extremely
long antennae. The puerulus actively swims inshore where
it settles to the bottom in shallow water and starts to
grow if the habitat is suitable.

The spiny lobster�s outer shell serves as its skeleton, and
is referred to as an exoskeleton. To grow, a lobster must
shed its exoskeleton. This process of molting is preceded
by the formation of a new, soft shell under the old one. An
uptake of water expands the new shell before it hardens.
Lobsters are vulnerable to predation and physical damage
right after they molt, until their new shell hardens.
Molt rates for the California spiny lobster are assumed
to be similar to those of the Japanese spiny lobster. A
0.24-inch CL specimen goes through 20 molts to reach 1.18
inches CL at the end of its first year. Four molts during
the second year will result in a carapace length of two
inches, and there are three molts in the third year. It
takes a lobster from seven to 11 years to reach a legal size
of 3.25 inches CL. Spiny lobsters molt annually, following
the reproductive period, once they reach 2.5 inches CL.
Growth rates, or the period between molts, are highly
variable. They have been correlated with food availability,
size, and sex. The larger an animal, the slower it grows.
Injuries or disease will often result in a slowing or complete
cessation of growth until the injury has been repaired.
Juvenile lobsters usually spend their first two years in
nearshore surf grass beds. Sub-adults have also been
found in shallow rocky crevices and mussel beds. Adult
lobsters are found in rocky habitat, although they also
will search sandy areas for food. During the day, spiny
lobsters usually reside in a crevice or hole, dubbed a den.
More than one lobster is usually found in a den. At night,
the animals leave their dens to search for a wide range
of food. Adult lobsters are omnivorous and sometimes
carnivorous. They consume algae and a wide variety of
marine invertebrates such as snails, mussels, sea urchins,
and clams as well as fish, and injured or newly molted
lobsters. Lobsters are eaten by sheephead, cabezon, kelp
bass, octopuses, California moray eels, horn sharks, leop-
ard sharks, rock fishes and giant sea bass.

A large portion of the spiny lobster population makes
an annual offshore-onshore migration that is stimulated
by changes in water temperature. During winter months,
male and female lobsters are found offshore at depths
of 50 feet and deeper, although individuals of both sexes
have also been found in shallow water in winter. In late
March, April, and May, lobsters move into warmer onshore
waters less than 30 feet. The higher temperatures on
shore shorten the development time for lobster eggs.
Nearshore waters also have a more plentiful supply of
food. In late October and November, the onshore waters
cool, and most lobsters move offshore. Winter storms that
cause increased wave action in shallow water encourage
this movement. Lobsters generally move after dark and in
small groups across the sand.

California spiny lobsters of both sexes reach maturity at
five or six years and 2.5 inches CL. After maturity, male
lobsters grow faster, live longer, and reach larger sizes
than the females. Males can live up to 30 years, and
females at least 20 years. There are records of male Cali-
fornia spiny lobster weighing over 26 pounds and attaining
lengths up to three feet. Today, lobsters over five pounds
are considered trophy-size.Trophy-size animals are usually
taken by recreational divers.

Status of the Population

Population size is unknown for the California spiny lob-
ster. Commercial landings have fluctuated through the
years and are influenced by some factors that are inde-
pendent of the health of the population.

The closed season protects egg-carrying and molting
female lobsters. The size limit ensures that there will be
several year classes of broodstock, even if all legal-size
lobsters are caught each season. The escape port has
been effective in reducing the capture and handling of
juvenile lobster. An illegal market has always existed for
�shorts � (undersized lobsters). Public education and ade-
quate warden enforcement are key elements in reducing
this problem.

The Department of Fish and Game has had a commercial
logbook system in place since 1973. Catch effort, the
numbers of legal and short lobsters taken, number of
traps fished, and depths where the traps are fished are
required information on the logs. The presence of shorts is
generally a good indicator of a healthy fishery.

History of the Fishery

Since the late 1800s, there has been a commercial fish-
ery for California spiny lobster (Panulirus interruptus )
in southern California. Commercial fishermen use box-like
traps constructed of heavy wire mesh to capture spiny
lobsters. Traps of other materials, such as plastic, are
allowed, but wire traps remain the most popular. About
100 to 300 traps per fisherman is common, but some fish
as many as 500 at the peak of the season. The traps are
baited with whole or cut fish and weighted with bricks,
cement, or steel. They are fished on the bottom, and
each trap is marked with a buoy bearing the fisherman �s
license number followed by the letter P. High-speed boats
in the 20 to 40-foot size range are popular in this fishery,
but everything from 15-foot skiffs to 50-foot fishing boats
are used. Most trap boats are equipped with a davit and
hydraulics to assist in pulling the traps.

Commercial lobster fishing occurs in shallow, rocky areas
from Point Conception to the Mexican border and off the
islands and banks (such as Cortes and Tanner banks) of
Southern California. Some marine life refuges and reserves
are closed to the take of lobster, as are areas in Santa
Monica and Newport Bays and at Santa Catalina Island.
Sophisticated electronic equipment enables trappers to
find suitable lobster habitat and relocate their traps there.
Traps are fished along depth contours in waters less than
100 feet, or clustered around rocky outcrops on the bottom.
At the beginning of the season the traps are usually very
close to shore. By the end of the season they are in 100 to
300 feet of water.

Seasonal landings in the 200,000 to 400,000 pound range
rose following World War II and peaked in the 1949-1950
season, with a record 1.05 million pounds landed. A gen-
eral decline followed for the next 25 years, reaching a
low of 152,000 pounds in the 1974-1975 season. Landings
started back up the next season, but remained between
400,000 and 500,000 pounds for nine consecutive seasons
from 1979-1980 to 1987-1988. The next nine years the
landings ranged from 600,000 to 800,000 pounds with
a peak of 950,000 in the 1997-1998 season. Landings
dropped back down after that. The peaks and valleys that
have characterized this fishery are not unexpected in a
fishery that is strongly in influenced by the weather, El Ni�o
and La Ni�a events, and the export market.

About 90 percent of the legal lobsters taken in the com-
mercial fishery weigh between 1.25 and 2.0 pounds, which
produces the size of tail desired for the restaurant trade.
Most of the harvest in recent years has been exported
to Asian countries and France. However, depressed econo-
mies overseas have resulted in an effort to re-establish
domestic markets. The price paid to the fisherman is in
the range of $6.75 to $8 a pound. The largest portion of
the commercial and sport harvest is always taken during
the first month of the season, October, which also is the
highest month of trapping effort. The effort and catch
drop off sharply in January through the middle of March
(the season �s end). San Diego County, being the most
central to the spiny lobster�s range, usually produces the
highest landings, followed by Los Angeles/Orange, and
Santa Barbara/Ventura counties.

Commercial and recreational lobster fishermen are
restricted to a minimum size limit of 3 1/4 inches carapace
length (CL). Historically, the season for both has run from
early October to mid-March. Since 1992, the sport season
has opened the weekend before the first Wednesday in
October, the official commercial season opener. Com-
mercial fish traps, including lobster traps, must have a
destruct-device of a type approved by the Department of
Fish and Game. This is to ensure that lost or abandoned
traps do not continue to capture marine life indefinitely.
Since the 1976-1977 season, it has been required that
lobster traps be fitted with rectangular escape ports (2
3/8 by 11 1/2 inches) to minimize the retention of undersized
lobsters. This requirement has been credited with reversing
the long downward trend in landings previous to that.

A formal commercial restricted access program was initi-
ated in April of 1997. All lobster fishermen are required
to have an operator permit ($285). Deckhands that assist
them must have a lobster crewmember permit ($125).
Recreational harvesters need a valid sport fishing license
with an ocean enhancement stamp, and may use hoop
nets or bare (gloved) hands when skin or scuba diving
for lobster. No appliance, such as a fish spear or a short
hooked pole, may be used to snag the animals from deep
crevices or caves. The daily bag limit for sport fishing is
seven lobsters, reduced from 10 in 1971.

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