QuickTime and a TIFF (Uncompressed) decompressor are needed to see this picture. 4/9/2014 Hybrid Walleye (Saugeye)- The Wisconsin Experience Jim Held Aquaculture Outreach Specialist UW-Extension jaheld@wisc.edu Why Walleye? High market value Wide-spread reputation as a food fish Limited domestic supply Established fingerling production methods 1
Why Not Walleye? Aggressive behavior Easily disturbed by shadows and movement Poor growth rate under intensive conditions Diminution in growth rate before market size (especially in males -sexual dimorphism) Hybridization The advantages of some hybrid crosses are very obvious Bear + Deer = Beer? 2
With certain fish species, interspecific crossbreeding has resulted in hybrids having behavioral and growth characteristics better suited for intensive culture than those of purebred fishes. BUT NOT ALWAYS! Examples: Muskie x Northern Pike---Tiger Muskie Plaice x European Flounder White Bass x Striped Bass--- Sunshine or Palmetto Bass Yellow Perch x Eurasian Perch Natural hybridization between walleye and sauger has been documented, and both reciprocal hybrids have been artificially propagated in the laboratory. 3
Hybrid walleye (Saugeye) have been stocked for resource enhancement in as many as 11 states. Limited impact? Heterosis-Hybrid Vigor Fertility Overview Growth studies over a decade ago established that walleyesauger hybrids grew as much as 2 times faster than the purebreds. Organoleptic studies concluded that the hybrid walleye fillets compared favorably with farm-raised purebreds, both of which were preferred to wild-caught purebreds. Improvements in early spawning and fry feed-training techniques provide the opportunity for out-of-season fingerling production as well as eliminate the need for a pond phase of production. Taken together these statements suggest that hybrid walleye may be an ideal candidate for commercial RAS food fish production. 4
Question: Can we produce a food-size hybrid from egg to plate in one year with only indoor systems? Objectives Use early season spawning and fry feed-training techniques to produce hybrid walleye fingerlings in indoor systems. Document key production characteristics for the grow-out of hybrid walleye to food size in RAS. Provide farmers with food-size adult and feed-trained hybrid fingerlings for market potential and field trials. 5
Spawning and Feed-training Early season spawning went as anticipated. Two injections of hcg @500IU/kg 24 hours apart. Initially, brood stock sauger males were a challenge. Otohime diet, B1,B2, C1, 1.0mm Silver cup Fry training success was hard to quantify and highly variable. There was a learning curve. 85% survival from 4 inches to market size. Materials and Methods Experimental Tank Setup for Initial Rearing 230 L round tanks Sidewalls painted black Gray bottom Adjustable lighting Flow 24 hr feeders Surface spray Removable screens Daily cleaning system 6
Surface spray Directional water flow Center screen Fry Feed Otohime fry feed 200-1400 m Nelson Silvercup walleye grower 1.0mm 7
20mm 60mm Walleye/Saugeye Growth 400.0 300.0 200.0 Yellow perch market size Hybrid target market size Saugeye Walleye 100.0 0.0 4/23/09 5/7/09 5/21/09 6/4/09 6/18/09 7/2/09 7/16/09 7/30/09 8/13/09 8/27/09 9/10/09 9/24/09 10/8/09 10/22/09 11/5/09 11/19/09 12/3/09 12/17/09 12/31/09 1/14/10 1/28/10 2/11/10 2/25/10 3/11/10 Date 8
Weight Gain 350 300 Saugeye 250 200 Hybrid target market size 150 100 Yellow perch market size Walleye 50 0 4/20/12 5/20/12 6/19/12 7/19/12 8/18/12 9/17/12 10/17/12 11/16/12 Date 12/16/12 1/15/13 2/14/13 3/16/13 4/15/13 1 year old Hybrid Walleye(1.0kg) 9
Results Brood stock injected in mid-april. Average fish size reached market target by December 1. Larger fish could be culled for sale by early November. Marketing could continue through the following March 50% yield for scaled skin-on fillets. Good market acceptance. Challenges Availability of sauger brood stock Fry training learning curve Cannibalism Rearing density in RAS (55 kg/m 3 ) Economics 10
Acknowledgements This study is funded by State of Wisconsin support of the University of Wisconsin Stevens Point Northern Aquaculture Demonstration Facility and Wisconsin Department of Agriculture, Trade and Consumer Protection Agricultural Development and Diversification Program grant # s 23001 and 25007. We also appreciate the assistance of the U.S. Fish and Wildlife Service (Genoa, WI). 11