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New Crops News, Spring 1991, Vol. 1 No. 1

Soft-Shell Crayfish: A New Crop for Indiana

Preliminary evaluations carried out in the summer of 1990 indicates that the potential for soft-shell crayfish production in Indiana using native species is extremely promising. Research at Purdue University is focuesd towards filling a market niche in one of the largest aquacultural industries in the U.S. with a native species. Characteristics of a potential Indiana industry are similar to those for the southern U.S. crayfish industry, but production is offset seasonally reflecting the biology of each species group.

Aquaculture was the most rapidly growing segment of U.S. agriculture during the decade of the 1980s, and crayfish aquaculture consistently ranked second or third largest during that period. However, crayfish production in the historically-important production areas of Louisiana is a seasonal enterprise. A typical production season in the southern U.S. begins in November when females lay eggs and ends by June of each year. At this time, their crayfish burrow and enter a relatively dormant state until fall. Seasonal activity patterns in native midwestern crayfish are exactly offset.

Native midwestern crayfish lay eggs in early spring and the juveniles grow through the summer and fall. Most of our species do not burrow in winter and will actually gain weight during this period, although activity is greatly reduced. Thus, the native species of Indiana are available during the time of year when there is no competition from other regions of the U.S.

Crayfish markets involve two distinct segments — hard-shell and soft-shell. One of the most rapidly growing segments of crayfish aquaculture has been soft-shell production. Crayfish have to molt, or shed their confining exoskeleton, to grow. Immediately after a molt, they are soft and almost completely edible. Soft-shell producers buy hard-shell crayfish for $1.10/kg, hold those animals in indoor systems for 1-6 weeks, and harvest a commodity with a retail price of $8.80-$14.00/kg after molting. Clearly, the potential profit margin has been one of the reasons soft-shell crayfish aquaculture has been growing. However, there have been no evaluations of this potential new crop using native Indiana crayfish species.

Two evaluations were formally undertaken at Purdue this past year and the results of those studies suggest that crayfish can be moved into controlled situations, with molting occurring within 1-4 weeks. We also found that crayfish collected in late fall (November) would not molt. Thus, there is a limit to production here as there is in Louisiana. However, their limitation is in summer and fall, whereas ours appears to be in winter and possibly spring. We will evaluate the spring limitation this coming year.

Temperature, the environmental factor evaluated to date, impacts molting activity, but several other environmental factors may influencing molting such as photoperiod, (length of daylight) and water levels. These factors will be formally evaluated next spring and summer.

Close contacts have been maintained with researchers from Louisiana State University and our results parallel theirs. They appear excited about the possibility of a year-round supply of crayfish from the U.S. and have been willing partners in our studies.

Identifying new crops for Indiana’s farming community is a vital endeavor and should reap benefits in terms of economic development. Native crayfish species are one of the many new crop opportunities for development in Indiana.

Paul B. Brown
Department of Forestry
and Natural Resources
Purdue University
West Lafayette, IN 47907-1165

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