Ovarian development and induced
oviposition of the overwintering swimming crab Portunus trituberculatus
(Brachyura: Portunidae) reared in the laboratory
K. Hamasaki,
H. Imai, N. Akiyama, K. Fukunaga-2004
Fisheries
Science, 70(6):
988-995
Abstract:
Females of the swimming crab Portunus trituberculatus were
cultured under natural temperature and high temperature (21°C) conditions
to examine ovarian development and oviposition from autumn (October) to the
beginning of breeding season in the following spring (May). Ovaries
developed because of vitellogenesis of oocytes from October to December and
their developmental state did not change during the overwintering period
from December to March. In spring, from late March to mid May, some ovaries
reached prematuration and maturation stages and ovipositions began from
mid-late April under natural temperature conditions. Females reared in tanks
of high temperature regimes oviposited earlier than those reared in tanks of
natural temperatures. The number of days to oviposition tended to decrease
with advancement of the beginning times (early February to late April) of
culture of females under high temperature regimes; induced ovipositions were
achieved more easily with increasing photoperiod from c. 12 h in
early February to c. 14 h in late April. Therefore, it is inferred
that the temperature and photoperiod are important environmental factors
controlling ovarian development and oviposition.
(Tamano
Station, National Center for Stock Enhancement, Fisheries Research Agency,
Tamano, Okayama 706-0002, Japan, Email: hamak@s.kaiyodai.ac.jp)