Assessment of yellowtail
kingfish (Seriola lalandi lalandi) reproductive
physiology, as a basis for aquaculture development
C.W. Poortenaar, S.H. Hooker, N. Sharp-2001
Aquaculture, 201(3-4): 271-286
Abstract:
Patterns of gamete development, size at sexual
maturity, seasonal changes in gonadal condition and reproductive
endocrinology were investigated in the yellowtail kingfish Seriola lalandi
lalandi. Samples were collected by commercial and recreational
fishers along the East and West coasts of Northern New Zealand, between
September 1998 and March 2000. Changes in the size distributions and
proportions of oocyte stages during ovarian development indicated multiple
group synchronous oocyte development and the presence of all developmental
stages of oocytes in mature ovaries indicated a capacity for multiple
spawning within a reproductive season. Changes in developmental stages of
gametes during testicular development and the presence of all gamete stages
(excluding spermatogonia), in partially and fully spermiated males,
indicated multiple group synchronous gamete development in males. The
smallest mature female was 775 mm fork length (FL), 50% of females reached
sexual maturity at 944 mm FL and 100% at 1275 mm FL. The smallest mature
male was 750 mm FL, 50% of males reached sexual maturity at 812 mm FL and
100% at 925 mm FL. Gonadosomatic index (GSI) provided a useful basic
measurement of gonadal anabolism. Seasonal changes in gonad stage and GSI
indicated that S. lalandi lalandi were spring-summer
spawners. Blood plasma concentrations of testosterone (T) and 17β-estradiol
peaked in females during vitellogenesis, and plasma concentrations of 17α20
β -dihydroxy-4-pregnen-3-one (17,20 β P) were significantly
elevated in females with ovaries undergoing final oocyte maturation. Blood
plasma concentrations of 17,20 β P did not change with gonadal
development in males; however, plasma concentrations of 11-ketotestosterone
and T were significantly elevated in partially and fully spermiated males.
Blood plasma steroid profiles from natural cycles provide a benchmark to
gauge reproductive performance in captive and domesticated fish. This study
provides baseline information required for successful reproductive
management of S. lalandi lalandi.
(National Institute of Water and Atmospheric
Research, NIWA, P.O. Box 109-695, Newmarket, Auckland, New Zealand, Tel.:
+64-9-375-2090; fax: +64-9-357-0024, e-mail: c.poortenaar@niwa.cri.nz)