1918.] The N.Z. Journal of Science and Technology. 137 
summers pass with scarcely any perceptible migration. The causes of this 
variation in abundance are not known at all. These shoals are often several 
miles in length, and their course is marked by great flights of predatory 
birds—gulls, petrels, &c.—which accompany them, and by shoals of barra- 
couta and other fishes which harass them. Occasionally they are driven 
ashore on the beaches in vast quantity. In Queen Charlotte Sound this 
fish is known as the “ Picton herring,” and is cured; but the price of labour 
makes their capture and subsequent treatment as “ sardines ” very impro¬ 
bable. They would make excellent fish-meal, however. 
The sprat (Amblygaster antipodus) is always abundant on the coast. It 
could be used like the sardine. It constitutes one of the most important 
sources of food of the larger fishes, and at the Portobello Hatchery it has 
been recorded from the stomachs of several species. It is the chief feed of 
the barracouta. 
There are some other marine animals which may be mentioned in this 
connection, though they are not fishes. 
Porpoises and dolphins are most valuable for their skins and oil, while 
their flesh desiccated would prove useful for pig-meal or cattle-meal, and 
for fertilizer. The fishery is quite neglected in local waters. 
Whale-feed: Enormous quantities of the pelagic larvae of Munida sub- 
rugosa occur in the southern coastal waters for several months of the year. 
The shoals are often of great size, and colour the sea red in bright patches. 
The bodies contain numerous oil-globules, and an investigation is much 
required as to the oil and manurial value of this crustacean. Thousands 
of tons could be got in sheltered harbours, even when boats could not go 
out in the open sea for fishing. 
By-products from the Fisheries. 
All unmarketable fish and all offal can be utilized for the production of 
oil and manure, though it is questionable whether it would pay to make a 
business of bringing in fish to a port for this express purpose. Yet I have 
seen the trawlers catch tons of such fish and simply tip them overboard 
again. Offal must, of course, be dealt with. In making manure the oil 
must be removed first, not only for its own sake, but because its presence 
in manure is troublesome and inhibitory to its proper fertilizing action. It 
is impossible to quote any definite figures for this manufacture. As a 
general basis, Professor Prince, referring to the dogfish, says that “ about 
8 tons of raw material are required to produce 1 ton of scrap, and from 
8 to 12 gallons of oil may be produced from a ton of dogfish.” 
In Canada—before the war—fishermen were paid $2 (or 8s. 4d.) a ton 
for fish-offal, and exactly double that rate for dogfish. The fertilizer pro¬ 
duced from this source sold at $30 to $35 (£6 to £7) per ton, and the oil 
from 5d. to Is. 3d. per gallon. It is quite certain that no fishermen in New 
Zealand would take the trouble to bring into port—unless the fishing-ground 
was within a mile or two—either poor fish or fish-offal at such a figure. On 
the other hand, the pre-war price of really good fish-manure would be from 
£9 to £11 per ton, and of fish-oil probably not less than 2s. per gallon. Most 
of the fish-manures sold at the present time are of very poor quality, being 
mixed with far too much sand, powdered limestone, or other padding. 
A certain quantity of the latter—enough to keep the mixture free and dry, 
so that it will run freely in a drill sowing-machine-—is perhaps almost neces¬ 
sary. In some parts of America, dried powdered kelp is used for mixing with 
the fish-refuse. 
