Mauchline ( 1972) attrmptd t o est iinttt (1 thv longevity of bathypelagic
crustiwrtins by corn perison with the growth rates of epipelagic species
living in latitudes higher than 40°, and he stated that bathypelagic
ruphausiids ttnd mysids live 2-7 tsimrx as long as epipelagic ones. If
his eRtilTliLte is applied to the bnthypelagic: shrimps, then Hymenodoro
*fronloZia m d [ I . ylucialis, which attuin IL b0d.v length of about 40-60
trim, rnny not, mature sexually until their second or third year of life
wid lttrgc spec.imens are probtthly ti 8 ycurs old. My unpublished data
from the wutms sirrroiinding Japiiii indicate that the life-span of the
mesopelagic qwcies in the generit f h n a d a s , Sarge~tes and h‘ergia is one
or two ywrs: Pasiphaea s‘p. mcttures at iLge of 1-5-2 years and lives for
2.5- 3 yews. I’robebly the spcc-icw of Oplophorus, Acanthephyra and
h’gstulluxpis attain sexual ~nat~urity in the second, but mostly in the
third, year of their lives and producc a sequence of broods within the
next one or two years.
11. Dispersion and migration
The ~ g g s
of 8eryia lucens are generally spawned in the innermost
part of Siiruga Bay, whcre the prc-spawning aggregation is found near
t,he mouths of thc rivers. Recituse of the movement of the water mass,
the larvae disperse seaward ilfter hatching, and the protozoea and
zoen lttrvuc twe found more or lcss evenly distributed in the upper
layers of the bay. Some of tliern itre ciwied to the open sea and are
protmbly iinable t,o return to their birthplace. Maintenance of the
larvae in thc coastal water worild be Iargdy accomplished by landward
transport by flood tides, the intcrnul mixing of salt wedges, and the
cddics ciinsed by jet strcams in thc estuaries. At the same time, the
semi-enrlosed coiuiterclockwise horizontal circulat.ion of water infiurnoed by tlie Kirroshio appears to affect the retention of Sergiu
larvae iii this bay. There is certnin evidence to suggest that the
stability and intensity of the circ!ulating current during the breeding
season uct as irnportant factors determining the size of the shrimp
population. The post-larvae tfevvlop fairly good locomotive powers
mid gradiitllly niove landward. Adolcsccnts oc!cur mainly in the western
part of the buy in autumn and whtw, und the adultn reenter the said
rrstricted waters in the next spring to spawn (Fig. 18).
The spawniiig of Acetes japonir.w ~ H O
take8 place in the innerrno&
part of Ariake Sect (Ikemtitsu. J953). The pmt-larvae move to deep
water in the c.cvitmtl part in ltite aiitumn and stay there in winter.
They cwnics I)iiclc inshore again iir the wrly spring on the tidal currents.
On tlie othw hand, the bentJiic penaeicls Penaeus dwrrzrum Burkenroad and P.japowicus Bate spawn offshore. They migrate into brackish
crustiwrtins by corn perison with the growth rates of epipelagic species
living in latitudes higher than 40°, and he stated that bathypelagic
ruphausiids ttnd mysids live 2-7 tsimrx as long as epipelagic ones. If
his eRtilTliLte is applied to the bnthypelagic: shrimps, then Hymenodoro
*fronloZia m d [ I . ylucialis, which attuin IL b0d.v length of about 40-60
trim, rnny not, mature sexually until their second or third year of life
wid lttrgc spec.imens are probtthly ti 8 ycurs old. My unpublished data
from the wutms sirrroiinding Japiiii indicate that the life-span of the
mesopelagic qwcies in the generit f h n a d a s , Sarge~tes and h‘ergia is one
or two ywrs: Pasiphaea s‘p. mcttures at iLge of 1-5-2 years and lives for
2.5- 3 yews. I’robebly the spcc-icw of Oplophorus, Acanthephyra and
h’gstulluxpis attain sexual ~nat~urity in the second, but mostly in the
third, year of their lives and producc a sequence of broods within the
next one or two years.
11. Dispersion and migration
The ~ g g s
of 8eryia lucens are generally spawned in the innermost
part of Siiruga Bay, whcre the prc-spawning aggregation is found near
t,he mouths of thc rivers. Recituse of the movement of the water mass,
the larvae disperse seaward ilfter hatching, and the protozoea and
zoen lttrvuc twe found more or lcss evenly distributed in the upper
layers of the bay. Some of tliern itre ciwied to the open sea and are
protmbly iinable t,o return to their birthplace. Maintenance of the
larvae in thc coastal water worild be Iargdy accomplished by landward
transport by flood tides, the intcrnul mixing of salt wedges, and the
cddics ciinsed by jet strcams in thc estuaries. At the same time, the
semi-enrlosed coiuiterclockwise horizontal circulat.ion of water infiurnoed by tlie Kirroshio appears to affect the retention of Sergiu
larvae iii this bay. There is certnin evidence to suggest that the
stability and intensity of the circ!ulating current during the breeding
season uct as irnportant factors determining the size of the shrimp
population. The post-larvae tfevvlop fairly good locomotive powers
mid gradiitllly niove landward. Adolcsccnts oc!cur mainly in the western
part of the buy in autumn and whtw, und the adultn reenter the said
rrstricted waters in the next spring to spawn (Fig. 18).
The spawniiig of Acetes japonir.w ~ H O
take8 place in the innerrno&
part of Ariake Sect (Ikemtitsu. J953). The pmt-larvae move to deep
water in the c.cvitmtl part in ltite aiitumn and stay there in winter.
They cwnics I)iiclc inshore again iir the wrly spring on the tidal currents.
On tlie othw hand, the bentJiic penaeicls Penaeus dwrrzrum Burkenroad and P.japowicus Bate spawn offshore. They migrate into brackish