McDonald, Michael EDeVore, PhilipRichards, CarlSkurla, James AGunderson, JeffreyKutka, FrankMerrick, Glenn2015-02-272017-04-142015-02-272017-04-141992https://hdl.handle.net/11299/187220The potential to develop a viable crayfish industry in Minnesota currently exists. Crayfish biomass in our inland lakes can greatly exceed that of fishes; existing harvest techniques appear to have very little impact on the year-to-year crayfish population. Thus, Minnesota's crayfish appear to be an abundant and resilient resource. There are markets for soft and hard shell crayfish for food, soft and hard shell crayfish for bait, and peeled tail meat. A Minnesota crayfish product could currently be inserted in any of these markets, but crayfish as a bait appears to be the most attractive market. There is a very high seasonal demand for bait crayfish and the wholesale prices can be in the range of $15 to $25 per lb for soft shells. In addition to bait markets, large hard shell crayfish for food have a strong international export market, but this market requires that sufficient quantities be shipped at the right times. Also, there is local interest in peeled tail meat for retail sale. We examined four widely distributed Orconectes species (O. virilis, O. propinquus, O. rusticus, O. immunis) to assess commercial soft shell production potential. Crayfish were held in production-sized shallow trays with 2 cm of water at constant temperature similar to that used for commercial soft shell production. Molting success was examined as a function of capture date, sex, and stage of maturity. The timing of life cycle events dictates to a large extent the availability and soft shell production potential of wild caught crayfish, particularly in northern latitudes where market-sized crayfish are often nonjuveniles. Adults typically molt two to three times per growing season, associated with reproductive cycles. Molting rate in the laboratory was highest when crayfish were captured just prior to the wild molt. The first molt of the season was much more synchronous than the second molt. Molt timing varied by sex. Premolt Orconectid crayfish did not change color like Procambarus sp. but could be identified by the decalcification of the cheliped merus. The harvest of several species may be required to optimize soft shell production since synchronous molts occur at different times for different species. Our economic assessment of the crayfish food market suggests that it is relatively flat. This is due to: continued high production costs (including the lack of a proven tail meat separator); regional consumption (primarily in the south-central and Pacific states); unsophisticated packaging and marketing; and seasonally available supply. Crayfish are used in much of the Midwest for fishing bait. Since it is illegal to sell live crayfish for bait in Minnesota, markets in other states will have to be targeted. Problems to overcome include reducing mortality of crayfish shipped to out-of-state markets and drops in sales when crayfish are available closer to the markets. We have analyzed the economic feasibility of food and bait soft shell crayfish production facilities using flow-through and recirculating systems for the first two years of operation. Bait crayfish production in a recirculating system appeared to be the most profitable operation and food crayfish production in a flow-through system appeared to be the least profitable operation. The processing of large quantities of crayfish for a commercial tail meat operation in Minnesota requires that an inexpensive, automated system be developed in order to maintain the product's economic viability. We have evaluated the necessary engineering design components for developing a relatively inexpensive automated crayfish processing system, which could be linked to extant tail meat extruders. We feel that such a system is feasible, and could cost less than $15,000 retail.enCrayfishMinnesotaNatural Resources Research InstituteUniversity of Minnesota DuluthTechnical Report