Spermatogenesis in reciprocal hybrids of Atlantic salmon (Salmo salar  L., 1758) and sea trout (Salmo trutta trutta  L., 1758) during their freshwater period

Abstract

Summary Development of gonads and the course of spermatogenesis were studied in 1–2 years old reciprocal hybrids of Atlantic salmon and Sea trout grown. These fish were produced under controlled conditions and raised in restricted natural water courses. Histological analysis (light microscopy) revealed that spermatogenesis in these two types of hybrids was without significant deviations from normal. Early maturing males produced sperm in their first and second years. The percent of maturing individuals and the sexual cycle was similar in the reciprocal hybrids and close to that of the parent species. In the first year of life early maturing males represented 12 and 13% of trout × salmon and salmon × trout hybrids, respectively, while in the second year this percentage raised to 83 and 100%, respectively. During the first year all maturing males of the reciprocal hybrids underwent incomplete maturation, producing a low number of mature germ cells. This feature is also typical in 1 year old fish of the parental species.