Procambarid Crawfish: Life History and Biology

SRAC Publication No. 2403 VI September 2007 PR Procambarid Crawfish: Life History and Biology W. Ray McClain1 and Robert P. Romaire2 Crawfish (or crayfish) have social, dering the Gulf of Mexico from Texas favorable. The red swamp crawfish economic and ecological significance to Alabama, northward up the Missis- produces more, but smaller, eggs in several regions around the world, sippi River drainage into Tennessee than the white river crawfish. The including the southern United States. and Illinois, and southward into east- red swamp crawfish appears to be Louisiana dominates the crawfish ern Mexico. The red swamp crawfish better adapted to nutrient-rich waters industry of North America in both has been introduced in other areas of and may tolerate higher water tem- aquaculture and wild capture fish- the U.S. (including Hawaii) and in at peratures, although these differences eries. Crawfish also are cultivated for least 19 other countries in Central have not been confirmed. The white food in Texas, Arkansas, Mississippi, and South America, the Caribbean, river crawfish grows faster at cooler Alabama, South Carolina and North Europe, Africa and Asia. The white temperatures and can attain a slight- Carolina, and are consumed in these river crawfish is found in the south- ly higher maximum size of about 130 and many other states. However, ern states along the Gulf of Mexico grams (3.5 crawfish per pound). there is no place where crawfish and northward up the Mississippi Anecdotal evidence indicates that the have had more impact on the econo- River drainage, possibly as far as the red swamp crawfish is usually more my of a region than in Louisiana, confluence of the Mississippi and abundant in standing water habitats where the industry contributes well Ohio Rivers. The eastern white river with low dissolved oxygen, such as in excess of $150 million to the crawfish is found along the Atlantic swamps. Hence the common name state’s economy annually. coastal plain into southern New red swamp crawfish. England. Both red swamp and white river Species of importance The red swamp and white river crawfishes do well in commercial Procambarus clarkii (the red swamp crawfishes, and to a lesser extent the crawfish ponds, and both thrive in crawfish) and P. zonangulus (the eastern white river crawfish, have the low-energy-input, extensive aqua- white river crawfish) are the species similar ecological requirements. The culture systems used in Louisiana of greatest commercial importance in red swamp and white river crawfish- and other southern states. Though the southern U.S. Procambarus acutus es often co-exist in the same native the abundance of each species can acutus, sometimes referred to as the habitat or managed impoundment. vary among ponds and within a pond eastern white river crawfish, is culti- Both are ecologically adapted to the during the 7- to 10-month production vated in several states along the east annual hydrological cycles of spring cycle, the red swamp crawfish most coast of the U.S. and is nearly indis- flooding and summer dry periods often dominates the catch and is the tinguishable from P. zonangulus. common to large river systems and most desired species in the market- These crawfishes belong to the phy- floodplains in the region. Both place, particularly in Louisiana. lum Arthropoda (subphylum species construct simple shallow bur- White river crawfish are usually Crustacea), order Decapoda, and rows, to which they retreat to repro- most numerous in ponds that have family Cambaridae. The red swamp duce and survive temporary dry peri- been in continuous cultivation for crawfish is native to the states bor- ods. One notable difference between several years; it occasionally becomes the two species is that, in the South, the dominant species over time. the white river crawfish is a seasonal The factors that govern the relative 1 Rice Research Station, Louisiana State spawner, reproducing only in the fall abundance of the two species in University Agricultural Center and winter. Red swamp crawfish may production ponds are not fully 2 Aquaculture Research Station, Louisiana State spawn at any time during the year University Agricultural Center understood. Research has shown when environmental conditions are that the species that enters the pond first in greatest numbers after As the common names suggest, south (2 years or less), have relatively fall flood-up is likely to dominate adults of the white river crawfish are high juvenile survival rates, and can the population. Thus, if red swamp off-white to tan, while the adult red alternate between sexually active and crawfish become established first swamp crawfish is red. However, inactive forms. P. clarkii can spawn after the pond is flooded, they will color alone is not a definitive distin- year-round in the southern U.S. and dominate the population and the guishing characteristic, particularly in females may reproduce more than later harvest. If juvenile white river immature crawfish. The large prima- once a year. ry claws or “chelae” of adult white crawfish become established before The life cycles of both red swamp river crawfish are more elongated red swamp crawfish juveniles enter crawfish and white river crawfish and narrow than those of adult red the population, white river craw- have evolved to allow them to adapt swamp crawfish. The areola, or space fish will dominate the population to the cyclical low-water dry condi- on the dorsal surface where the two and the subsequent catch. Despite tions and high-water flood conditions halves of the carapace meet, is wider efforts to limit the presence of common to their natural habitats. on white river crawfish. Also, the white river crawfish in ponds in Commercial crawfish aquaculture white river crawfish lacks the dark Louisiana (because it is less desir- simulates this hydrological cycle, but stripe on the underside of the tail or able in the marketplace), both with precise control over when ponds abdomen that is a distinguishing species are responsive to routine are flooded and when they are dewa- characteristic of red swamp crawfish. culture practices and often co-exist tered to optimize recruitment and sub- Sex is easy to distinguish in both in production ponds. sequent crawfish production. Mature species. Males have two sets of hard, There is no evidence that red swamp animals mate in open water and the calcified swimmerets next to the and white river crawfishes cross- sperm are stored in a seminal recepta- thorax; females have a seminal recep- breed naturally, although crossbreed- cle (annulus ventralis) on the underside tacle (annulus ventralis) and oviduct ing and hybridization have been of the female. The female may mate openings (Fig. 2). observed in other crawfish species. with more than one male and eventu- The red swamp and white river Life cycle ally retreats to the burrow to spawn. crawfishes are similar in appearance, Although spawning can take place in especially at a young age, and an Based on their distribution in North open water, the burrow provides pro- inexperienced observer might not be America, the red swamp and white tection while the eggs and offspring able to distinguish between the two river crawfishes are classified as tem- are attached to the abdomen. Females species. Several key anatomical fea- perate species; however, aquacultur- carrying eggs or hatchlings are highly tures are used to distinguish between ists generally regard them as having vulnerable to predators because the them (Fig. 1). traits normally associated with attached brood prevents the typical warmwater species. These crawfishes escape response, which is repeatedly are relatively short-lived in the deep SR CS Figure 1. Adult white river crawfish (Procambarus zonangulus), top left, have longer, narrower claws than red swamp crawfish (Procambarus Figure 2. Males (left) can be recognized by two pairs of hard, calcified swim- clarkii), top right. Red swamp craw- merets (CS) next to the thorax and spur-like protrusions at the base of the fish (bottom right) usually have a middle set of walking legs. On females (right), the seminal receptacle (SR) can dark line visible on the underside of be observed on the underside of the thorax between the last pair of walking the abdomen, whereas the white legs; with close observation, the oviduct openings can be spotted near the river crawfish do not. basal joints on the second pair of walking legs. and rapidly contracting the tail to propel itself backward very quickly. Crawfish can burrow for reproduc- tion at any time of the year but do so most often in late spring/early summer in the South. Crawfish of all ages and sizes, whether mature or immature, male or female, will construct burrows or retreat to existing burrows to survive periods of dewa- Figure 4. Extracted crawfish ovaries Figure 5. Female with hatchlings tering. Crawfish ponds are usually showing the various stages of maturi- attached to swimmerets beneath the drained from late April in some pro- ty, from well developed on the left to abdomen. duction systems to as late as July or immature on the far right. August in others. Before draining, mature crawfish burrow near the become separated from the female as water line (Fig. 3). As the water level been stored in the seminal receptacle, drops, crawfish burrows follow the she moves about in open water and and then are attached to the swim- they disperse in the pond. waterline. Some burrows are found merets (pleopods) under the tail on the pond bottom after draining, (abdomen) with an adhesive sub- Because spawning is largely syn- but those often contain a high per- stance called glair. Although crawfish chronized in pond-reared crawfish, centage of non-reproductive craw- can survive in a very humid environ- production ponds are routinely fish, such as males and immatures.

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