156
C. F. HICKLING
which have since been bred very successfully. I n a matter so important,
persistent effort may bring success.
The striped grey mullet has been induced to spawn in captivity in
Taiwan by Tang (1964). Live matura fish were collected at sea from
purse seiners and placed in holding boxes. They were subjected to
two hormone injections, 12 hours apart. Each injection consisted of
one pituitary gland from a mature grey mullet of the same size, ground
up in saline solution with 20 international units of a proprietary preparation of chorionic gonadotropin with hypophysial extract. The ambient
sea temperature was 20-25'C.
Tang had great difficulty due to the high mortality of the captive
fish-they would not live longer than 48 hours. He found that the
fertility of the eggs was low (32%) and that the hatching rate was less
than 10%. But this fine pioneering effort has since been improved
upon, with promising results in Hawaii and California and also in Israel
where the pituitary glands of common carp were used. This fish seems
t o be a universal donor but, at the time of writing, the young fish have
not developed beyond the 21st day. So final success, though obviously
very near, is still awaited. Success will mean that the grey mullet
farms of the future must have hatcheries as a part of their layout but
it is more probable that private firms or Government hatcheries will
specialize in the breeding of fry, and sell the well-grown fry to the
farmers.
The writer tried Tang's technique with Crenimugil Zabrosus in
February and March 1969, but had no success. The sea temperature
was very low, at about 7-9"C close t o the beach.
2. Prawns
This may be the best place in which to describe the Japanese
success with the rearing of the '' Kuruma " prawn, Penueus juponicus
(Bate). It is not a genuine case of breeding, as with the grey mullet,
because the female prawns will have already ovulated and been
fertilized before being caught for the rearing of their eggs.
The process is described by Hudinaga and Miyamura (1962). The
females are placed in a shallow wooden tank (2 x 1 x 1 m) full of
sea water at a temperature of about 28OC. The nauplius hatches out
13 hours after spawning and the larval prawn passes through the
stages of the zoaea and mysis in about a week.
On reaching the post-larval stage, they are transferred to a concrete
pond of 5 m2 area and 30 em deep for about 20 days. Then follow the
post-larval stages, leading to the attainment of a commercial size after
about one year.
C. F. HICKLING
which have since been bred very successfully. I n a matter so important,
persistent effort may bring success.
The striped grey mullet has been induced to spawn in captivity in
Taiwan by Tang (1964). Live matura fish were collected at sea from
purse seiners and placed in holding boxes. They were subjected to
two hormone injections, 12 hours apart. Each injection consisted of
one pituitary gland from a mature grey mullet of the same size, ground
up in saline solution with 20 international units of a proprietary preparation of chorionic gonadotropin with hypophysial extract. The ambient
sea temperature was 20-25'C.
Tang had great difficulty due to the high mortality of the captive
fish-they would not live longer than 48 hours. He found that the
fertility of the eggs was low (32%) and that the hatching rate was less
than 10%. But this fine pioneering effort has since been improved
upon, with promising results in Hawaii and California and also in Israel
where the pituitary glands of common carp were used. This fish seems
t o be a universal donor but, at the time of writing, the young fish have
not developed beyond the 21st day. So final success, though obviously
very near, is still awaited. Success will mean that the grey mullet
farms of the future must have hatcheries as a part of their layout but
it is more probable that private firms or Government hatcheries will
specialize in the breeding of fry, and sell the well-grown fry to the
farmers.
The writer tried Tang's technique with Crenimugil Zabrosus in
February and March 1969, but had no success. The sea temperature
was very low, at about 7-9"C close t o the beach.
2. Prawns
This may be the best place in which to describe the Japanese
success with the rearing of the '' Kuruma " prawn, Penueus juponicus
(Bate). It is not a genuine case of breeding, as with the grey mullet,
because the female prawns will have already ovulated and been
fertilized before being caught for the rearing of their eggs.
The process is described by Hudinaga and Miyamura (1962). The
females are placed in a shallow wooden tank (2 x 1 x 1 m) full of
sea water at a temperature of about 28OC. The nauplius hatches out
13 hours after spawning and the larval prawn passes through the
stages of the zoaea and mysis in about a week.
On reaching the post-larval stage, they are transferred to a concrete
pond of 5 m2 area and 30 em deep for about 20 days. Then follow the
post-larval stages, leading to the attainment of a commercial size after
about one year.