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Topics - fläshgreëniè

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General Flashlight Discussion / flashlight selling, Hongkong style...
« on: December 17, 2008, 11:15:36 AM »
Thought I share with you what I saw...  8)

Other Gear / ASP baton
« on: August 08, 2008, 07:34:41 PM »
Anyone know a good website for getting telescoping ASP baton. Looking to get some for home protection.

General Flashlight Discussion / new Barbolights
« on: November 27, 2007, 07:38:18 AM »
Just a head up for some new Barbolights over at CPF.

Talk Story / is Mr. Bulk a bad word???
« on: October 11, 2007, 01:15:06 PM »
This thread got me scratching my noodle...

Mr. Bulk / spiffy damcham
« on: August 28, 2007, 04:08:23 PM »
Thought I share some pics I tried to take of the spiff up damcham I got back from Dennis. Man, getting the hue and colours on photo is a pain...  >:(

Testing Grounds / increasing your clams
« on: August 21, 2007, 10:13:30 AM »
The hard clam industry is the
largest and most valuable of the
other clam species and represents
7 percent of all clams harvested
but accounts for 53 percent of the
dockside value.
Hard clams are bivalve mollusks
that live in saline waters and cannot
tolerate fresh water for any
extended period of time. Natural
distribution of hard clams is all
along the Atlantic coast from
Nova Scotia to Florida. They have
been introduced along the shore
of the Gulf of Mexico from Florida
to Yucatan. Hard clams have been
established along the West Coast
of the United States, in the British
Isles and parts of France.
Distribution of hard clams is
determined by hydrodynamic factors
that affect various pre- and
post-settlement processes and
may be related to geographic locations
such as sediment types and
depth. Sediment characteristics
and type affect the number and
types of invertebrate and fish
predators by their adaptation to
various bottom types. Hard clams
support a major commercial fishery
in the New England and Mid-
Atlantic Coastal states. New York,
Rhode Island, New Jersey and
Virginia are leading states for
hard clam commercial landings.
There is still a small commercial
clam fishery along the eastern
coast of Florida.
Life history
Reproduction cycle
Spawning of hard clams generally
occurs annually in the spring,
summer or fall. Clams spawning
naturally or spawned in hatchery
conditions have a larvae stage that
lasts 8 to 15 days. Spawning of
hard clams is stimulated by water
temperatures above 79oF or 26oC.
The optimal range of water temperature
occurs at different times
of the year at different latitudes.
Clam reproduction occurs earlier
in the year at lower latitudes.
Dimodal or polymodal spawning
takes place in southern populations,
and spawning activities
may take place more than once
per spawning season. Hard clams
exhibit latitudinal variability in
the timing of gametogenic events.
Gametogenesis or the production
of gametes (egg and sperm) is
part of the reproductive cycle.
There are several stages in the
reproductive cycle which for discussion
purposes may begin with
the resting and/or spent stage. In
this stage the individual clam is
completely or almost completely
lacking gametes and is followed
by the early development stage
characterized by an increase in the
follicle wall thickness and the
presence of immature gametes. In
the late development stage the follicles
are rapidly expanding to
accommodate the larger and more
numerous gametes. In the ripe
stage, the follicles are fully
expanded and thin-walled. The
lumen of female follicles contain
mature ova (eggs), and mature
sperm dominate the lumen of
male follicles. The germinal ducts






February 1995
SRAC Publication No. 433
Biology and Culture of the
Northern Quahog Clam
(Mercenaria mercenaria)
Wendell J. Lorio and Sandra Malone*
*Louisiana State University, Baton Rouge,
The northern quahog is commonly called
the hard clam and will be referenced as
such in this report. Mercenaria mercenaria
is one of 14 species that are harvested
in the United States. The scientific name
comes from the Latin word mercenaris
which means “hired for wages” or “hired
have begun to expand and may
contain a few mature gametes
and are therefore ready for actual
spawning to take place. The ripe
stage is followed by the resting
and/or spent stage and the reproductive
cycle is now complete.
Fertilization occurs externally in
the water column, and at the end
of 24 hours, the development of
the veliger larvae is complete.
These larvae swim and feed, but
in general are moved by tidal currents.
The larvae achieve a maximum
size of 200 to 275 microns.
By the sixth to tenth day the skinlike
outside tissue called the mantle
starts to form two shells and
the umbo. The umbo is the
rounded area of the shell just
above the hinge. Since the shell
provides extra weight, they no
longer swim freely and settle to
the bottom. Only 10 percent of the
originally fertilized eggs survive
to this stage. During metamorphosis,
the clam “seed” selects a
suitable substrate, where it burrows
at varying depths and maintains
limited mobility. The preferred
substrate is a combination
of mud and sand but other suitable
substrates are pure sand,
gravel and mud.
Larval setting
Many bivalve species are attached
to sand grains or other debris by
one or several strong byssus
threads. Byssus threads are thin
strands of material secreted by a
gland located in the middle line
of the surface of the foot in a
byssal pit. Hard clams lose their
ability to make byssus as they
grow older. Clams may release
from this attachment and may
crawl or be moved by currents to
another location where they
attach again. As clams mature
they use their muscular foot to
burrow into the bottom sediments.
By alternately extending,
swelling and contracting the foot,
the body is pulled down into the
bottom substrate. Generally the
complete body is below the substrate
except for the incoming and
outgoing siphons.
The body of the clam is completely
enclosed in a mantle, which is
subdivided into lateral lobes that
secrete a calcium carbonate shell.
The mantle, which is part of the
body, covers the foot and visceral
mass. The mantle is connected to
the shell by pallial muscles, which
are a short distance from the edge
of the shell. This line of mantle
attachment to the shell is represented
on the inner surface of the
shell as the pallial scar line.
The two valves of the shell are
joined dorsally by an elastic hinge
ligament, which acts as a spring
by exerting on the valves forcing
them apart when the adductor
muscles relax.
The dorsal margin of each valve
bears a prominence point near the
hinge ligament called the umbo.
This is the oldest part of the shell,
and around this part of the shell
are the concentric lines of shell
growth. Each umbo may point
slightly to the anterior so that it is
usually possible to determine
right and left valves.
An abundance of hard clams have
been correlated with sediment
types. The highest average of
abundance usually occurs on
shell-sand sediments. Sediment
characteristics also affect predation
success on hard clams.
Respiration and growth
Most clams remain close enough
to the surface so that the tips of
their siphons are exposed.
Siphons, sometimes called the
neck, are specialized tubes of the
mantle for the entrance and exit of
water. The siphons help clams
take in oxygen and food. One
siphon brings in water that carries
oxygen for respiration and food
for growth. Incoming water passes
over the gills where the oxygen
is absorbed and where algae and
other food particles are filtered
out. Small food particles are
drawn over the gills by the action
of cilia covering the gills and
mantle. Food is trapped by mucus
on the gills and carried vertically
by action of the cilia to the food
groove along the ventral edge of
the gill and then to the palos
around the mouth. Filtered water
and waste are then expelled by
the other siphon.
Growth of hard clams is affected
by tidal movement and algal concentrations
along the substratewater
interface. Ideal conditions
are moderate tidal movement
with dense algal concentrations
and adequate dissolved oxygen
levels above 4 ppm.
The rate of shell deposition is a
major factor in limiting growth.
Clam shells are formed by the
deposition of crystals of calcium
carbonate on an organic material.
Shells grow in rings and/or layers
deposited on this organic matrix.
Growth is not continuous but
incremental with periods of shell
dissolution. Shell growth occurs
only during aerobic respiration
when the valve is open. The mantle
which covers the inner surface
of the shell is responsible for shell
formation. The shell is deposited
between the inner shell surface
and the mantle epithelium. The
extrapallial fluid contains organic
matrix components and calcium
carbonate which react to form the
shell. The mantle secretes and
maintains organic and inorganic
components in the extrapallial
fluid. Shells grow laterally (thickness)
under slow growth conditions.
Faster growing individuals
generally have thinner shells.
All populations of hard clams,
whether natural or aquacultured,
grow at different rates which may
be influenced by genotype or
genetics. Hard clams with maximum
growth rates attain marketable
size in 24 to 36 months. In
10 to 16 months fast growers may
be twice the size of slow growers.
The relatively long period of time
needed to produce market size
clams is an important limiting factor
in the aquaculture of hard
clams. Approximately 10 percent
of any clam population originating
from the same spawning
matures at the fastest rate. Therefore,
it would be of economic benefit
if selection could be made for
the fastest growing individuals. It
has become apparent in clam
aquaculture that the removal of
slow growing animals from the
production system would result in
a net reduction in production cost.
The value of the animals discarded
exceeds the savings realized by
confining production to fast growing
individuals. Variable growth
rates affect production by increasing
handling, increasing stress to
the animals associated with
increased handling, and decreasing
the predictability of cash flow.
Environmental factors also influence
growth rates. Water temperature,
food availability, salinity,
water quality and tidal currents
provide food and dispense waste
products. Density and genetics are
major factors that determine the
growth rate of hard clams. The
hard clam is 1 to 2 inches long at
harvest with a meat weight of 18
to 20 grams (at approximately 3
years of age). Growth of clams
slows with increasing age. In
seven to eight years hard clams
may only be three inches long.
Hard clams are known to live for
30 years or longer. It has been
reported that hard clams exceeds
50 percent of the expected growth
by the third year and 20 percent
by the fifth year.
When clams are disturbed they
burrow deeper to avoid being
preyed upon. Common predators
are blue crabs, mud crabs, conch,
sting rays, horseshoe crabs and
snails. They mostly feed on juvenile
or small clams. Wading birds
may cause intensive destruction in
some areas.
Current techniques used to
exclude predators include rafts,
trays, cages and nets. Biological
control of crab predation has been
attempted by stocking toadfish in
culture trays. There has been a
significant increase in clam survival
with use of toadfish to
reduce the total numbers of blue
crabs, but the economic feasibility
is questionable.
Hard clams are marketed in
whole form, and approximately 30
percent of the harvested hard
clams are shucked. The remainder
of the harvested clams are marketed
for raw or steamed consumption.
This marketing form generates
the highest prices on a per
clam basis. Hard clam prices are
sensitive to changes in hard clam
supplies; as supplies increase,
prices decrease and vice versa.
Higher prices are received for the
smaller clams. Size class designations
may vary from state to state.
Generally the “littleneck” demands
the highest price.
“Little-neck” clams are approximately
48 to 50 mm at the longest
shell dimension. The availability
of edible hard clams is dependent
on the stocks of clams, access to
production areas, weather conditions,
and harvest seasons and
upon the bacterial content of their
Hard clam aquaculture
Hard clams are the most commonly
cultured of the bivalve species.
Clam culture in the United States
began with the first successful
rearing of larval hard clams in the
early 1920s. Broodstock management
is a vital step in fulfilling the
potential of hard clam aquaculture.
Efforts to produce genetically
improved bivalve broodstock
are probably as old as bivalve
mariculture itself.
There has been increased attention
in culturing hard clams in recent
years. Significant advances in production
technology during the
past decades have played a major
role in generating this growing
interest. Key innovations and
improvements in methodology,
especially the development of efficient
nursery systems and field
growout techniques, have
enhanced the economic feasibility
of culturing hard clams on a commercial
Production process
The hard clam aquaculture production
process consists of three
consecutive stages: hatchery,
nursery and grow-out. Each stage
is designed to produce a specific
size clam. The ultimate objective
is to produce hard clams for the
available markets.
The hatchery accomplishes the
spawning of broodstock clams
and raising the larval clams
through the postset stage to 1 mm
juveniles or seed clams. Broodstock
are held in conditioning
tanks with temperatures controlled
at 19oC and fed a diet of
cultured algae. Hard clams can be
stimulated into spawning in colder
months by conditioning them
gradually to increasing temperatures
in the laboratory, along with
adequate food.
The spawning process involves
manipulating the broodstock,
alternating exposures to chilled
(18 to 24oC) and warmed (28 to
30oC) seawater containing a suspension
of hard clam sperm. After
several cycles, the clams will
spawn, with the male usually
spawning first. The eggs are
sieved, collected and placed in
growing tanks where they develop
into larvae.
After spawning occurs, the next
phase of the hatchery process is
larval culture which lasts through
day 7. They are raised in various
sizes and types of containers. The
larval tanks are supplied with filtered
seawater (20 to 30 ppt) at a
temperature between 20 and 30o
C; usually an antibiotic or bacterial
inhibitor is added. The concentration
of larvae in the tanks
varies, but 30 to 60 larvae per tank
have been recommended. During
this stage they are fed a diet of
cultured algae.
Between day 8 and day 12 the larval
clams have developed into the
pediveliger stage. They are kept in
postset tanks and fed cultured
algae. Filtered seawater tempered
to 26oC circulates through the system
and assures maintenance for
optimum survival and growth.
of location in the water and being
subjected to damage by predators,
fouling and wave action. Survival
rates can be much higher for the
land-based systems due to greater
control over water quality and
lack of predators.
The length of grow-out time will
largely depend on water quality,
food availability and temperature.
Grow-out to 45 to 50mm market
clams from 7 to 15mm nursery
clams may require from 18 to 36
There are a variety of grow-out
culture systems for culturing hard
clams for the market. Grow-out
systems are stocked at a density of
50 to 75 seed/sq ft at final growout.
Although land-based growout
methods such as raceways
and tanks have been developed,
the field-based grow-out activities
are better suited for hard clam
production. Most grow-out operations
utilize some form of pen,
tray or net. Pens, nets and trays
are used in intertidal zones and
nets in subtidal and intertidal
zones. Pens are generally used
over soft bottoms while trays and
nets are used over hard bottoms
such as sand. Pens are harvested
by hand rakes or with mechanical
harvesters where legal. Trays are
harvested by lifting but because of
their weight a lifting apparatus is
required. Nets are placed over the
seed clam planted area and staked
down as a means to discourage
predators. Harvesting is accomplished
by rolling the net from the
planted areas and exposing the
clams to harvest by legal bottom
harvesting methods.
Increasing the chances of high
survival rate in clam culture
requires the use of seed clams
larger than 6mm shell height. The
larger the seed the more costly
they are and supplies are more
limited. As in any aquaculture
operation, clam culture is not
without risk as there is the slim
margin of economic viability. Call
on the fisheries or aquaculture
specialist in your state for additional
Postset clams are the next phase
of production which generally
lasts 13 to 35 days. As in earlier
stages water temperatures are
maintained at 26oC, water is filtered
and the postset clams are
fed cultured algae.
Under hatchery conditions, newly
set clams are placed in shallow
raceways or in cylinders with up
or down welling water flows. The
clam seeds are maintained in the
hatchery until they reach approximately
1 mm. At this point, seed
is graded and separated by size
and maintained in the nursery
until ready for planting.
Bivalve aquaculture has long been
plagued by an inability to culture
massive quantities of suitable
algal species economically. Algae
are needed to grow seed to the
proper size for field planting. The
cost of producing this algal biomass
is relatively high compared
to the cost of seed clam production
or the projected annual gross
revenue of this aquaculture venture.
The nursery is a critical link in the
hard clam grow-out process.
Placing seed clams from the
hatchery directly into the field
grow-out may yield an unacceptably
high level of mortality. The
nursery provides a controlled,
intermediate step, whereby the
hatchery-reared seed clams are
nurtured to a size less vulnerable
to the stress imposed in the field
grow-out phase. It would not be
cost effective to grow seed to the
size required for the grow-out
stage within an intensive hatchery
environment. Natural seawater is
generally used in these systems.
Natural feed is provided by seawater
as it moves through the
nursery system.
One method of nursery culture is
the land-based upflow method.
The upflow system utilizes ambient
seawater, which is pumped to
reservoir tanks and upflow cylinders
which provide vertical flow
for the seed clams. The flow of
water can be forced up through
the seed clams or pulled down
through the seed clams. The seed
clams rest on a fine mesh screen.
The movement of water serves to
remove waste and prevent suffocating
the seed from any accumulated
Another method of nursery culture
is called the land-based raceway
method. The raceway system
typically utilizes long, shallow
wooden trays which have been
lined with plastic or covered with
epoxy, resin or other protective
coating. A thin layer of sand covers
the bottom of each tray, over
which the seed clams are distributed.
Raw seawater is pumped
into one end of the tray at a prescribed
rate, so as to establish a
horizontal flow across the seed
The third method of nursery culture
is the field-based system,
which involves placing seed clams
directly from the hatchery into the
submerged bottom setting. Seed
clams smaller than 3 to 4 mm
should be utilized. Traditional
designs employ subtidal and
intertidal trays made of wood that
contain a layer of gravel or sand
and have a protective cover to discourage
Floating nursery trays are a recent
innovation. More recent innovations
include bottom bags and
systems of bags held together in
long belts. The series of bags significantly
reduces maintenance
and labor expenses. All of these
field-based nursery techniques are
placed in protected shallow water
areas so the threat of poaching can
be minimized.
These alternative nursery systems
vary considerably in terms of
investment cost, operational
expenses and management skill.
The land-based system requires
waterfront land and investment in
pumps, whereas the field-based
system is located on leased bottom
without need for controlled
water movement. Energy requirements
are much higher for the
land-based systems. Maintenance
costs are lower for the upflow systems
than raceways. Replacement
and maintenance costs are higher
for the field-tray systems because
The work reported in this publication was supported in part by the Southern Regional Aquaculture Center through Grant No. 89-38500-4516 from
the United States Department of Agriculture.

Talk Story / clam cult???
« on: August 20, 2007, 11:06:04 AM »
does this mean we might be a cult???   :P

Talk Story / 1k posting
« on: July 17, 2007, 08:11:35 AM »
I can't believe, 1000 posts...  :D :D :D

General Flashlight Discussion / to M6 or not to M6...
« on: February 26, 2007, 09:59:24 PM »
Well, here is my dilemma. As a collecting flashaholic, should I have a SF M6 in my collection or not???  :-[
Help me out, guys...
My attempt at a first poll.  8)

Talk Story / where to stay in SF
« on: February 05, 2007, 11:49:10 AM »
I am planning a trip to San Francisco with 2 other friends. Anyone have any suggestion on a cheap but not run down place to stay??
Also any suggestions on places to eat(not on the tourist radar) would be great too.

Talk Story / cheers
« on: December 07, 2006, 08:00:52 AM »
I know its a bit early but I will not be near computer soon till next year, Sooooo,
Merry Christmas and Happy New Year to everyone here. Hope all of you keep safe throughout the holidays...

 :occasion14: :occasion16: :occasion18: :wav: :tongue2: :spam4: :occasion1: :occasion15: :occasion16: :occasion14: :hugme:

Talk Story / singapore history
« on: September 19, 2006, 11:45:42 AM »
Singapore history in a song...
CY, you might need to explain a bit...

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