Responses of immature male masu salmon parr to the urine of mature males

Abstract

Responses of male masu salmon Oncorhynchus masou parr to mature male urine were investigated in a Y-maze trough. Immature masu salmon made fewer entries into the channel conditioned by mature male urine than that with control water. This phenomenon may suggest that immature males avoid sexually active males in the spawning season

Male urine signals social rank in the Mozambique tilapia (Oreochromis mossambicus)

“…In male tilapia, androgen levels (11KT) are good predictors of dominance [ 19 ], but their effect in urinary tract physiology or urination behaviour is not known. Mature masu salmon show morphological changes in the urinary tract suggesting a functional transition in the kidney related to the release of sex pheromones in both sexes [ 40 , 41 ]. Further investigation is necessary to determine which physiological mechanisms (e.g.…”

Transitions of urine flow rate and kidney-somatic index in mature masu salmon

“…The present results indicated that UFR and KSI increased in both sexes at mature stages. These increases may occur because not only mature females, but also mature males, release chemical signals in the spawning season 16 . An advantage of increased urine in spawning season will be effective diffusion for transmitting pheromone signals in both females and males, although the biological functions of pheromones are distinct between females and males.…”

“…These increases may occur because not only mature females, but also mature males, release chemical signals in the spawning season. 16 An advantage of increased urine in spawning season will be effective diffusion for transmitting pheromone signals in both females and males, although the biological functions of pheromones are distinct between females and males. It is suggested that in masu salmon the kidney acts as a pool for chemical signals and the urine is effectively released in spawning season.…”

“…[11][12][13][14][15] It was also suggested in masu salmon that avoidance pheromone was contained in the urine of mature males. 16 Therefore, when compared with immature fish, it has been speculated that the kidney in mature fish modifies functionally, suggesting either urine production or accumulation.…”

“…In salmonid fish, sex pheromones, which attract conspecific mature males or induce priming effects of final maturation, were present in the urine of ovulated females 11–15 . It was also suggested in masu salmon that avoidance pheromone was contained in the urine of mature males 16 . Therefore, when compared with immature fish, it has been speculated that the kidney in mature fish modifies functionally, suggesting either urine production or accumulation.…”