Chapter 9: Artificial Propagation of Paddlefish: An Overview of Developments
William L. Shelton, Steven D. Mims, Kenneth J. Semmens, and Rafael Cuevas-Uribe
Abstract.—Detailed knowledge of the life history of Paddlefish Polyodon spathula is a relatively recent scientific chapter. The foundation was initially established in Missouri, where there was a significant sport fishery for Paddlefish; initial observations on natural spawning and subsequent techniques for artificial propagation were developed there. Building on this impetus, a different trajectory was initiated in the late 1970s by our research group, one focusing on aquaculture with a goal of developing a breeding program to produce all-female progeny; our collaboration continued over the next three and one-half decades. Managed reproduction through artificial propagation, nursing of juveniles and grow-out for commercial production were components of this program, but more detailed techniques such as ploidy manipulation, sperm physiology, and cryopreservation were also developed. Our present objective is to highlight the improvements in artificial propagation that have been incorporated into hatchery programs. Initially, ovulation was induced with pituitary glands, but today Luteinizing Hormone Releasing Hormone analog (LHRHa) is used; ovulated eggs were collected by laboriously stripping, then a caesarian-section technique used in sturgeon was adopted, and subsequently the Minimally Invasive Surgical Technique (MIST) was introduced. Today, a Modified MIST technique offers a more efficient means of collecting eggs. Nursing of juveniles continues to evolve; primary nursing is now commonly done in tanks where fish may be offered live food during training to a prepared diet instead of starting culture in enriched ponds managed for zooplankton. The development of Paddlefish artificial propagation has benefitted from techniques which were initially developed and used in sturgeon culture. These operational hatchery techniques are common to both culture for restoration stocking and food fish production.