Maybe you've seen crayfish (or crawdads) in your local waters. Kids tend to
try and catch them.
More serious adults catch or raise them for food. At one time catching them for bait was
a very popular thing - but that has been discouraged since the Rusty crayfish can
really take over and decimate a place where they have been unknowingly introduced.
Some states have made it illegal to possess live crawfish while having angling equipment
in ones possession. The rusty crawfish is very aggressive and will displace native crawfish
species as well as underwater plants and other invertebrates.
My first experience as an adult with crawdads was in a restaurant outside Savanna
Georgia where the house special was big pots of boiled, drained crawdads were
dumped out on newspaper covered tables with steamed corn and containers of
melted butter. Wish I could remember the name of the place! It was flat wonderful.
We do get them in our local supermarkets from time to time.
Crayfish, (Decapoda) also called crawfish or crawdad, are closely
related to the lobster. It really is a miniature version of the lobster. More than half
of the more than 500 species occur in North America, particularly Kentucky
(Mammoth Cave) and Louisiana in the Mississippi basin. Crayfish also live in
Europe, New Zealand, East Asia and throughout the world, including the Tristan
da Cunha Islands. Nearly all live in freshwater, although a few survive in salt water.
Crayfish are characterized by a joined head and thorax, or mid-section, and a segmented
body, which is sandy yellow, green, or dark brown in color. The head has a sharp
snout, and the eyes are on movable stalks.
The crayfish is typical of most shrimp-like crustaceans and is characterized by a joined
head and thorax, or mid-section, and a segmented body, which is sandy yellow, green,
white, pink or dark brown in color.
Crayfish are usually about 7.5 cm (3 inches) long. Among the smallest is the
2.5-centimetre-long Cambarellus diminutus of the south-eastern
United States. Among the largest is Astacopsis gouldi of Tasmania;
its length may reach 40 cm and its weight about 3.5 kg (8 pounds).
The head has two pairs of sensory antennae and a pair of eyes on movable stalks.
The appendages, or pereiopods, of the thorax include four pairs of walking legs
which, as well as walking, are to probe cracks and crevices between rocks looking
for food. Crayfish also own one pair of claw-bearing chelipeds, which it extends
in front of its body while moving. These strong pinchers are specialized for cutting,
capturing food, attack, and defence. Some can grow to three inches in just the claw
length. A pinch can hurt! The crayfish also has several pairs of specialized food
handling 'legs,' bailers to cycle water over the gills, and five pairs of swimmerets
which are under the abdomen. All of these 'legs' can be regenerated if broken off.
Crayfish have a hard outside skeleton. This jointed exoskeleton provides protection
and allows movement, but limits growth. As a result, the crayfish regularly gets too
big for its skeleton, sheds it, and grows a new larger one. This is called molting. and
occurs six to ten times during the first year of rapid growth, but less often during the
second year. For a few days following each molt, crayfish have soft exoskeletons
and are more vulnerable to predators.
Crayfish, common in streams and lakes, often conceal themselves under rocks or
logs. They are most active at night, when they feed largely on snails, algae, insect
larvae, worms, and tadpoles; some eat vegetation (various water plants). Dead fish,
worms, corn, and salmon eggs are also favorites of the crayfish. Studies show that
adults (one year old) become most active at dusk and continue heavy feeding activity
until daybreak. Young crayfish are more likely to be the ones out during bright sunny
days, while the older crayfish are more active on cloudy days and during the night.
General movement is always a slow walk, but if startled, crayfish use rapid flips of
their tail to swim backwards and escape danger.
Most crayfish live short lives, usually less than two years. Therefore, rapid, high-volume
reproduction is important for the continuation of the species. Many crayfish become
sexually mature and mate in the October or November after they're born, but fertilization
and egg laying usually occur the following spring. The fertilized eggs are attached to the
female' swimmerets on the underside of her jointed abdomen. There the 10 to 800 eggs
change from dark to translucent as they develop. The egg-carrying female is said to be
'in berry,' because the egg mass looks something like a berry. Females are often seen
in berry during May or June. The eggs hatch in 2 to 20 weeks, depending on water
temperature. The newly-hatched crayfish stay attached to their mother until shortly
after their second molt.
The importance of the crayfish in a game fish's diet can be played up or down depending
on one's point of view. Down: Studies show that trout eat more aquatic insects than any
other item. Up: Biological studies also show that stream-living trout will select the largest
prey items that they can swallow. When crayfish are available, they will be eaten!
Crayfish are mostly found in warmer water, but do inhabit streams, rivers, lakes,
swamps, ponds and are familiar to any number of game fish. Even in cold trout
streams, large trout seem to recognize a good meal!
Because species and crayfish colors vary, it's best to fish with a fly that matches
the natural. Fish them in shallow, rocky places, for crayfish favor these areas.
Flies should be tied to they can be retrieved backwards, the way that crayfish
always swim. Fishing at dawn, dusk, or during the night would best imitate natural
movement. The retrieve should be a zip-zip-zip which matches the movement of
the repeated flicks of its abdomen.
For more on crawfish and the flies to imitate them, read
Al's Crayfish,
and Rock's Crayfish.
~ LadyFisher
Credits: Information from,
www.mackers.com and Aquatic Entomology by W. Patrick McCafferty,
drawing from the same. Photo from The Life of The Pond published by
McCraw-Hill.
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