Cultivation of Triple Hybrids of Russian, Siberian, and Amur Sturgeons at a Warm-Water Fish Farm

Abstract

This study provides biological, fishery, and production characteristic of spawning females of a triple hybrid between the Russian sturgeon, Siberian sturgeon, and Amur sturgeon (RS × SS) × AS and other commercial hybrid sturgeon forms grown in the cages of a warm-water fish farm in Primorsky Krai, Russia. The survival rate of larvae and juveniles of the triple hybrid in conditions of warm-water pools and the survival rate of marketable-size sturgeon was higher than those of Amur sturgeon and hybrids between the Russian and Siberian sturgeons. The weights of the triple hybrid individuals at an age of 3 and 4 years were 1.58 and 2.36 kg, respectively. These values were higher than those recorded for the hybrids between Russian and Siberian sturgeons and close to the standard values for Amur sturgeon. The fish productivity reached 94 kg/m² of cage, or 134 kg/m² of cage taking fish that were sold into account. The values of this index were much higher than the standard values not only for Amur sturgeon, but also for other sturgeon species and hybrids. Up to 93% of the females reached maturity after being treated with a hormone-stimulating drug. The first female of the triple hybrid sturgeon became mature at an age of 9 years with a body weight of 13.1 kg. Maturation of the other females of the same year-class was stretched in time and lasted for 7 years, up to 16 years of age. Approximately 75% of them reached maturity at an age of 10–12 years. The maximum recorded weight of a female triple hybrid was 29 kg at an age of 14 years. The inter-spawning interval for 97% of females was 1–2 years. The average annual yield of hard roe obtained from one female at an age of 9–16 years per spawning event was 2.28 kg; the weight of one egg was 17.6 mg; the fecundity was 132 000 eggs; the relative working fecundity was 7440 eggs/kg; the oosomatic index was 12.8%. The values of most of the production indices for the female triple hybrids were intermediate between those characteristic of the initial species used for crossbreeding. For three or four spawning seasons, an average of 5.25 kg of hard roe, or 30% of body weight, was obtained from one female triple hybrid. The roe yield from the most productive females was 10.8–11.0 kg, or 55–73% of body weight. The roe of the triple hybrid sturgeon was distinguished by high quality and was used for manufacturing food products. Females were technologically well adapted for roe stripping and showed a high survival rate of approximately 98% during long-term exploitation. Thus, the triple hybrid of the Russian, Siberian, and Amur sturgeons can be recommended for commercial cultivation with a high production output at warm-water sturgeon farms. Female triple hybrids can be used for the production of quite large amounts of high-quality food caviar. Their roe yield is lower than that in Amur sturgeon and does not differ significantly from the roe yield in the hybrid between the Russian and Siberian sturgeons.