The relationship between sperm density, spermatocrit, sperm motility and fertilization success in Atlantic halibut, Hippoglossus hippoglossus

H.B. Tvedt, T.J. Benfey, D.J. Martin-Robichaud, J. Power-2001

Aquaculture, 194 (1-2): 191-200

Abstract:

The commercialization of Atlantic halibut, Hippoglossus hippoglossus, aquaculture has been hampered by a failure to obtain consistently high fertilization rates. The principal goal of this research was to determine the optimum sperm density for successful fertilization of Atlantic halibut eggs. Sperm densities ranged from 2×10¹¹ to 6×10¹¹ spermatozoa/ml at 23% and 99% spermatocrit, respectively, for 36 milt samples collected from 17 males. Regression analysis showed a significant positive linear relationship between sperm density and spermatocrit, supporting the use of spermatocrit as a rapid estimator of sperm density in this species. There was no relationship between sperm density and sperm motility (defined as time elapsed from activation until <5% of the spermatozoa maintained forward swimming activity). Implant with a salmon gonadotropin releasing hormone analogue (GnRH(a); Ovaplant(TM)) was followed by a reduction in sperm density, but this affected neither the relationship between sperm density and spermatocrit, nor between sperm density and sperm motility. There was no effect of sperm density on fertilization success within the range of sperm:egg volume ratios of 1:15.6 to 1:8000, equivalent to 4.6×10⁸ to 9.4×10⁵ spermatozoa/egg, respectively.

(Department of Biology, University of New Brunswick, Fredericton, New Brunswick, Canada E3B 6E1)

home