Sexual Maturation and Milt Quality of the San Pedro Mártir Trout Using an Artificial Photoperiod

Abstract

The sexual maturation and milt quality of the San Pedro Mártir trout Oncorhynchus mykiss nelsoni (SPMT) were studied in captivity using an artificial photoperiod and a recirculating system that kept the water quality within the range recorded in the natural habitat of this subspecies. During the 21.8 months of the study, male SPMT reached the highest weight (379 ± 48 g [mean ± SD]) and total length (344 ± 19 mm) recorded for this type of trout. Male maturation was induced at 7.5 months. Eight ripe males (200-320 mm total length) were stripped by abdominal pressure to obtain milt on six occasions from January to April 2009, at intervals ranging from 2 to 4 weeks. Spermatozoa motility varied from 80% to 95%, with a maximum duration of 50-55 s. Milt volume ranged from 165 to 228 µL per organism, and spermatozoa concentration ranged from 235 × 10 6 to 4,772 × 10 6 cells/mL. The mean spermatozoa flagellum length was 33.17 µm, and head width and length were 2.14 and 2.72 µm, respectively. This work demonstrates that San Pedro Mártir trout can be maintained and induced to mature sexually in a recirculating system using artificial photoperiod and temperature control. This information can be useful in management and conservation programs for this endemic trout in Mexico.

Cold storage of the sperm of the endemic trout Oncorhynchus mykiss nelsoni: a strategy for short-term germplasm conservation of endemic species

“…In March 2007, 11 wild SPMT males were captured and maintained at the Banco Periférico de Germoplasma del Noroeste of the Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE, BPGN). The organisms were kept under artificial photoperiod during 7.5 months in a 250-L fiberglass tank connected to a recirculating system until maturation (Aguilar-Juárez et al, 2011).…”