THE BEHAVIOUR AND PEIYSIOLOQY OB HERRING AND OTHER CLUPEIDS 283
c. Predation on larvae
While this may well be an important source of mortality (Marty,
1966), nothing is known of its extent in the sea, although some predatory species have been noted. Lebour (1923) described plankton
investigations where herring larvae were observed in the guts of various
species of medusae, in the ctenophore Pleurobrachia and in T q -
teris. Larvae were also taken with Sqitta attached to them. This was
also observed in Sardinops caerulea by Arthur (1956). Marshall et al.
(1937) reported an absence of herring larvae in the Firth of Clyde,
possibly due to predation by medusae and ctenophores, while Stevenson (1947, 1962) cited ctenophores as preying heavily on the larvae of
Clupea p a l h i i . Lebour (1924) and Arthur (1966) report cannibalism in
herring and Bardinups respectively, adults eating the young. The latter
also reviewed the work done on the possible effects of phytoplankton
and metabolites on clupeid lazvae.
H. Salinity tolerance and om-regulation of larvae
1. Salinity tolerance
This has been studied in newly hatched herring larvae by Holliday
and Blaxter (1 960) and Bishai (1 961a), and in Clupeapalhii by Kurata
(1969). Figure 1 shows the salinity tolerance of herring larvae. The
most striking feature of the results is the very wide tolerance of the
larvae, from 14-60%, over 24 hr, and 2-5-52.5%, over 168 hr. Bishai
(196la) found that herring larvae lived longer in salinities from 10-15%, ,
than in higher or lower salinities. The 24-hr values quoted for Clupeu
pallasii by Kurata were from 1.06-69.5%,. Kurata also gave figures for
10-day-old Iarvae (1.06-66-5%,,) and 20-day-old larvae (2.45-40*25%,).
No abnormalities of development were reported by these workers.
However, Kryzhanovsky (1956) reported that if Baltic herring eggs,
which normally develop in water of salinity 4-5%,, were transferred to
salinities of 25%, then abnormal development and death of the larvae
occurred. Stevenson (1962) suggested that larvae of Clupeu palhii
might die in the open sea due to its high salinity. It would appear that
other clupeids have a wide salinity tolerance, for instance Perceva
(1939) found that larval Cmpiakwa caspia would survive in fresh and
" salt " water.
2. Osmotic regulation
Holliday and Blaxter (1960) showed that the tolerance of herring
larvae was based on a process of active regulation. If the larvae were
transferred from sea wafer to any salinity within their tolerance range
c. Predation on larvae
While this may well be an important source of mortality (Marty,
1966), nothing is known of its extent in the sea, although some predatory species have been noted. Lebour (1923) described plankton
investigations where herring larvae were observed in the guts of various
species of medusae, in the ctenophore Pleurobrachia and in T q -
teris. Larvae were also taken with Sqitta attached to them. This was
also observed in Sardinops caerulea by Arthur (1956). Marshall et al.
(1937) reported an absence of herring larvae in the Firth of Clyde,
possibly due to predation by medusae and ctenophores, while Stevenson (1947, 1962) cited ctenophores as preying heavily on the larvae of
Clupea p a l h i i . Lebour (1924) and Arthur (1966) report cannibalism in
herring and Bardinups respectively, adults eating the young. The latter
also reviewed the work done on the possible effects of phytoplankton
and metabolites on clupeid lazvae.
H. Salinity tolerance and om-regulation of larvae
1. Salinity tolerance
This has been studied in newly hatched herring larvae by Holliday
and Blaxter (1 960) and Bishai (1 961a), and in Clupeapalhii by Kurata
(1969). Figure 1 shows the salinity tolerance of herring larvae. The
most striking feature of the results is the very wide tolerance of the
larvae, from 14-60%, over 24 hr, and 2-5-52.5%, over 168 hr. Bishai
(196la) found that herring larvae lived longer in salinities from 10-15%, ,
than in higher or lower salinities. The 24-hr values quoted for Clupeu
pallasii by Kurata were from 1.06-69.5%,. Kurata also gave figures for
10-day-old Iarvae (1.06-66-5%,,) and 20-day-old larvae (2.45-40*25%,).
No abnormalities of development were reported by these workers.
However, Kryzhanovsky (1956) reported that if Baltic herring eggs,
which normally develop in water of salinity 4-5%,, were transferred to
salinities of 25%, then abnormal development and death of the larvae
occurred. Stevenson (1962) suggested that larvae of Clupeu palhii
might die in the open sea due to its high salinity. It would appear that
other clupeids have a wide salinity tolerance, for instance Perceva
(1939) found that larval Cmpiakwa caspia would survive in fresh and
" salt " water.
2. Osmotic regulation
Holliday and Blaxter (1960) showed that the tolerance of herring
larvae was based on a process of active regulation. If the larvae were
transferred from sea wafer to any salinity within their tolerance range