Paddlefish are endemic to most rivers and tributaries of the Mississippi basin and are found in 22 states of the United States. In 1989, US Fish and Wildlife Service (USFWS) listed paddlefish as a category 2 species because data were lacking on its population status. In 1992, USFWS added paddlefish to the list of Appendix II of the Convention on International trade in Endangered Species of Wild Fauna and Flora (CITES) primarily due to concerns about illegal poaching in the international caviar trade. Therefore, paddlefish aquaculture will provide alternative fish sources for the marketplace in the era of strict federal and state regulations on wild populations. Aquaculture of paddlefish is in a research and developmental phase. Most broodstock are obtained from wild sources, though some mature fish have been developed in captivity. Artificial propagation techniques are resulting in > 80 % egg fertility. Larval paddlefish are initially raised in organically fertilized, zooplankton-rich (i.e. Daphnia sp.) ponds, and then trained on extruded trout/salmon diets until the juvenile fish are > 30 cm in total length. Tank culture is also an alternative for raising juvenile fish. Juvenile paddlefish, a filter feeder that requires zooplankton as its primary food, are being grown in reservoirs and in polyculture with channel catfish (Ictalurus punctatus) in Kentucky, Indiana, Missouri and Alabama. Production yields are 200–400 kg·ha–1 in polyculture and in reservoirs ranching resulted in 55–175 kg·ha–1. Reservoir ranching is ideal for caviar production; whereas, paddlefish (1.5 to 4.0 kg) cultured with catfish is for meat production. A system to produce all-female progeny through artificial propagation with sex-inverted, gynogenetic broodstock and attempting to develop optimal cryopreservation techniques for the milt of these unique broodstock is currently being tested. Value-added products such as hot and cold smoked paddlefish are the major effort being developed for the marketplace. Consumer acceptability of value-added products from paddlefish has been better than channel catfish.

Cinq mille larves de poisson-spatule Polyodon spathula agéesde 3–4 jours, en provenance du Missouri aux États-Unis, ontété introduites dans l’ex-URSS, en 1974 dans le cadre des accords decoopération scientifique entre les deux pays. Cette première tentativen’a été que partiellement réussie ; seuls quelquessurvivants ont atteint 600–900 g après 2 ans puis lamaturité sexuelle et se sont reproduits en 1984 et 1986. L’élevagede cette espèce étant apparu possible, de nouvelles introductions ont eulieu, l’une en 1976, qui fut sans succès et une autre en 1977,réparties dans deux écloseries (Goreachi Cluch et Krasnodar-Ikreanoe). En1978, une centaine des spécimens de Goreachi Cluch ont étéexportés en Moldavie et élevés en polyculture dans plusieurspiscicultures où la reproduction de trois femelles a été obtenue en1988 et 1989. Des juvéniles issus de ces reproductions ont étéexportés en URSS (Ikreanoe) et en Roumanie et Hongrie. Par ailleurs, la stationde recherches de Nucet en Roumanie a importé des larves de poisson-spatule desÉtats-Unis en 1992, 1993 et 1994 (environ 2000 larves à chaqueintroduction). Dans ces différents pays, des recherches ont étéconduites sur cette espèce. Actuellement, la production commerciale adébuté en Russie et Moldavie pour la chair, et il a étémontré, dans le cadre d’un projet CE Copernicus, qu’il étaitpossible de produire du caviar. P. spathula peut venir en complément ouen substitution partielle de carpes, en polyculture et a une valeur commerciale plusélevée. Le problème est que la seconde générationprésente en Russie, Moldavie, Roumanie, et peut être en Hongrie, estdérivée d’un nombre limité de parents, avec des risques deperte de variabilité génétique.

The potential of carp pituitary powder (CPP) at one dose, or the luteinizing hormone-releasing hormone (LH-RH) analogue, des–Gly10,(D–Ala6)–LH-RH–ethylamide, at three different doses to stimulate spermiation in paddlefish (Polyodon spathula) was tested. Single injections of the LH-RH analogue at 0.2, 0.1, or 0.05 mg·kg–1 increased the number of spermatozoa per kilogram of body weight (kg–1 b.w.) by 4.7, 3.4, and 3.4 times respectively compared to control, but the number of spermatozoa per kilogram of body weight decreased with CPP (4 mg·kg–1) by 1.7 times compared to the control. The LH-RH analogue prolonged active spermiation, with numbers of spermatozoa ranging from 7.69 to 1.19 × 109 kg–1 b.w. up to 96 h after treatment. Analysis of variance showed significant influence of experimental groups on volume of sperm per male and per kilogram of body weight, and the total number of spermatozoa per kilogram of body weight, but insignificant influence on the total number of spermatozoa per male. The percentage of motile spermatozoa was not different between experimental groups for sperm collection at different times after injection. A very high positive correlation (r = 0.93) was obtained between sperm concentration and sperm transmittance measured with a spectrophotometer. This relationship was described with the following linear regression: sperm concentration (× 109 mL–1) = 1.3244 X–0.9969, where X is the percentage of sperm transmittance.