Pelagic Tunicata — Bary 
113 
against temperature and salinity (Fig. 22) bears 
this out. Over-all occurrences conform to the 
area of chief concentration being coincident 
with that of the "Southern” Subantarctic species 
(Fig. 20), but on the other hand, highest num- 
bers were present in the area of the "Northern” 
Subantarctic species. The narrow limits of salin- 
ity (34.15 to 34.63 °/oo) in which it is present 
are within those of subantarctic water (Dea- 
con 1937). The temperature range of 8.2° to 
14.5° C. is indicative of some degree of toler- 
ance, but it would appear that specimens are 
being carried into the warmer coastal waters 
(e.g., Stations 330 , 304) in water of subantarctic 
origin. The very numerous specimens at Station 
178 are in coastal water, but evidence from oc- 
currences of other species suggests that mixing 
may have taken place in this vicinity at an 
earlier time. Specimens possibly are resident in 
the subantarctic water (compare Thysanoessa 
gregaria; Bary, 1959^) which would extend the 
usual "warm-water” habitat to include a "cool- 
water” habitat about southern New Zealand. On 
the other hand, the species may have been car- 
ried southward from warmer northern waters, 
e.g., from the Tasman Sea. The disintegrating 
specimens from Station 921 lend support to 
such a suggestion. 
Oikopleura dioica 
O. dioica usually inhabits mixed, tropical and 
warm waters, but prefers coastal areas to the 
open ocean (Essenberg, 1926a: 486; Thomp- 
son, 1948: 39). The few occurrences in Lachlan 
samples also indicate adherence to coastal waters 
(Fig. 18^, and see Bary, 1959^). Temperatures 
are usually higher than for O. fusiformis (Fig. 
22). It is believed that when O. dioica was col- 
lected with O. fusiformis (Stations 79, 330) 
(or when it occurred in water of similar prop- 
erties to that from which O. fusiformis was 
captured) it was the result of coastal water hav- 
ing become mixed with water of subantarctic 
origin. 
For neither O. dioica nor O. fusiformis from 
New Zealand is there enough information to 
show whether there is variation of numbers dur- 
ing January, February, and March, nor whether 
their distributions are related to the depth of 
water as one proceeds offshore (Bary, 1959 h) . 
Pyrosoma spp. 
Very extensive shoals of Pyrosoma, almost 
entirely P. atlanticum, were encountered be- 
tween 10 and 20 miles seawards from Dunedin 
in late March and during April, 1951. Almost 
all specimens were aggregated into long lanes, 
or smaller or larger patches (Bary, 1953). 
Patches and lanes might occur over an extensive 
area at the surface, but when proceeding through 
a particular concentration, the colonies were 
seen to become progressively deeper in the 
water, eventually passing from sight. Oblique 
tows consistently collected large numbers, how- 
ever, which suggests that the concentrations of 
specimens continued at depth. Such a vertical 
and horizontal distribution bears a striking re- 
semblance to the hypothetical distribution of 
swarms of salps proposed by Hardy (1936: 519, 
fig. 7), and is of interest in relation to Sewells 
(1953: 85) comment that P. atlanticum is "most 
common at some depth below the surface.” 
The concentrations continued over several days, 
sometimes a number being present, at others, 
only one or two. Similar large shoals have been 
reported on several occasions from about Cook 
Strait. It is possible therefore they are a regular 
summer feature, at least along the eastern South 
Island coast. 
The stomach contents of two fish, Blue Cod 
and Hapuku ( Parapercis colias and Polyprion 
oxygeneios) , caught by hand line off Stewart 
Island in February, confirmed fishermens re- 
ports that Pyrosoma (the so-called "jelly” or 
"oatmeal”) was common in late summer and 
autumn, to the extent that their catches were 
often depleted through the fish "being overfed 
and not biting.” Of several hundred cod stom- 
achs examined all but a few contained Pyrosoma, 
to about 8 cm. long. The colonies therefore 
must be counted as an important, although only 
seasonally abundant, fish food in this area. Off 
Dunedin, very large shoals of fish were present 
at the surface among the Pyrosoma aggregations, 
but it could not be verified that Pyrosoma was 
in fact being taken as food. 
Fig. 19- Occurrences and distribution of pelagic tunicates in relation to temperature, between Wellington 
and the Auckland-Campbell Islands, New Zealand. 
