Sex organ extracts and artificial hormonal compounds as sex pheromones to attract broodfish and to induce spawning of Chinese black sleeper (Bostrichthys sinensis Lacepede)

Ovarian, testicular and seminal vesicle extracts of mature Chinese black sleeper (Bostrichthys sinensis Lacepede), synthetic steroids 17[alpha]-progesterone (17[alpha]-P), 17[alpha],20[beta]-dihydroxy-4-pregnen-3one (17[alpha],20[beta]-P) and prostaglandins PGE₂ and PGF[subscript 2[alpha]] were used in an attempt to attract broodfish and to induce spawning. Furthermore, 17[alpha]-P, PGE₂ and PGF[subscript 2[alpha]] levels were determined in extracts, and PGE₂ and PGF[subscript 2[alpha]] levels were determined in holding and spawning waters. The results showed that ovarian extracts attracted more males than females to enter artificial nests, while testicular and seminal vesicle extracts attracted more females than males. The highest percentage of spawned nests were found when 17[alpha],20[beta]-P and PGE₂ were administered to the nests, while the largest egg numbers and the mean highest fertilization rate were observed when PGE₂ was added. In ovarian extract, 17[alpha]-P level was higher than levels in testicular or seminal vesicle extracts. The PGE₂ levels were significantly (P