Louisianans associate Mardi Gras and early spring with eating crawfish. It has become a tradition and a part of our rich culture. However, through early March of 2014, crawfish have been in short supply, therefore very expensive.
The culprit is prolonged cold winter temperatures. During normal winters, water temperatures dip into the 50’s with the passage of cold fronts, but quickly rebound into the 60’s with the return of warmer days between fronts. During these warm-up periods, crawfish become active, feed and grow through molting.
This winter we did not have breaks between fronts allowing water temperatures to warm. Crawfish, being cold-blooded animals are not very active in water temperatures below 60 degrees. When water temperatures fall below 60, crawfish become almost dormant, not moving, feeding or growing very much.
Crawfish will eat almost anything including living and decomposing vegetation, seeds, algae, microorganisms, and a myriad of aquatic insects, invertebrates and small fish. Although vegetation is the most abundant food source in crawfish ponds, it is thought to contribute little to the direct nourishment of crawfish. Nutrition comes from the microbial rich organisms found colonizing dead and decaying plant and animal matter (detritus) in aquatic environments.
While detritus sustains most natural, aquatic food chains, the really high quality protein and energy rich foods required to maximize crawfish production comes from consuming animal matter such as insects, insect larvae, worms, snails, fish, etc. These organisms are commonly found in detrital rich aquatic environments. When water temperatures are this low, the entire aquatic ecosystem is slowed down.
Spring crawfish production has many variables that affect the timing and volume of production. One of the most important environmental variables is summer rainfall. In most situations, crawfish burrow into the ground during the drier months of the summer. They will burrow as deep as they have to in order to maintain water and humidity in the burrow.
Frequently, this is also when crawfish reproduce. As long as there is ample rainfall, soil moisture ensures good survival of the brood and adults. However, during dry summers the crawfish must burrow deeper into the ground seeking water. This reduces survival because of lack of moisture over the crawfish’s gills and the extra energy required expanding burrows, which sometimes collapse.
For this season, as days become longer and water temperatures rise into the 60’s and 70’s crawfish will become more active and supplies should pick up. Most folks in the crawfish industry believe we will have a decent crawfish season; it may just be delayed a few weeks.
A very wise crawfish farmer told me once, “one sure thing about crawfish production; it’s unpredictable.”