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Volume 56, 1926
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Food of New Zealand Fishes.

[Read before the Wellington Philosophical Society, 28th October, 1924; received by Editor, 12th November, 1924; issued separately, 26th April, 1926.]

A Paper dealing with the food-supply of New Zealand fishes was published in 1892, * and in 1921 records of the food of over thirty species were made by the same author. In the first work are compilations of food in 12,000 stomachs examined by lighthouse-keepers, and in the second there are valuable contributions to our knowledge of the food of common species in Otago waters.

The examination of 114 stomachs of ten species discussed in this paper was undertaken with a view to obtaining preliminary data on the exact nature of food-supply of fishes during the autumn months in Palliser Bay and Cook Strait. Fish taken from the stomachs were examined in like manner to ascertain their food-supply, which was invariably found to consist of copepod-remains, algae, shrimps, and squids.

I have to thank Professor W. B. Benham, F.R.S., of the Otago University, for undertaking the identification of the worms from the fishes' stomachs. I wish also to thank Professor Chas. Chilton, D.Sc., of the Canterbury University College, Christchurch, for assistance in connection with the identification of the Crustacea, and Mr. W. R. B. Oliver, F.L.S., for assistance with shell-fish.

The following details show the nature of the stomach-contents of a number of fish from Palliser Bay, Cook Strait, &c.:—

Dactylopagrus macropterus (Forster): Tarakihi.
Trawled in Palliser Bay, Cook Strait, April, 1922.

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No. Worms. Spatangoid Sea-urchm. Algae. Other Materials.
1 Glycera ovigera, Limbriconereis sphoerocephala, &c. Remains Quantity Copepod eggs.
2 Limbriconereis sp Remains Diatoms?
3 Several Quantity
4 Owenia fusiformis Small quantity
5 Remains Small quantity Crabs and starfish remains.
6 In intestine
7 Remains Quantity Malletia australis; sand and gravel.
8 Quantity Sand and gravel.
9 Traces Traces Malletia australis; sand and gravel.
10 Traces Small quantity Some sand.
11 Remains Large quantity Starfish-remains.
12 Limbriconereis sphoei ocephala Large quantity
13 Starfish-remains.
14 In intestine
15 Glycera ovigera, Limbriconereis sphoerocephala In intestine In intestine
16 Limbriconereis sphoerocephala Remains Quantity
17 Remains In intestine
18 In intestine
19 Gasteropod without shell.
20 Remains Quantity

[Footnote] * G. M. Thomson, Notes on Sea-fishes, Trans. N.Z. Inst., vol. 24, p. 206.

[Footnote] † G. M. Thomson and T. Anderton, History of Portobello Marine Fish-hatchery, Board of Science and Art-Bull. No. 2, p. 67.

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From the above data it may be concluded that the tarakihi (Dactylopagrus macropterus) feeds on the sand formations of the bottom. Out of twenty stomachs examined, fifteen contained algae, and this comprised the major portion of all the material. Less than half the stomachs examined contained worms or spatangoid sea-urchin. G. M. Thomson (loc. cit.) has recorded the following foods: shell-fish, fish, seaweed, Crustacea, squids, and sand-worms.

Latridopsis ciliaris (Forster): Moki.
Trawled in Palliser Bay, April, 1922.

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No. Worms.* Algae. Crabs. Amphipods Other Material.
1 Potamilla lac iniosa In intestine Sand and mud in intestine.
2 P. lac. Sand in intestine.
3 P. lac. Mactra scalpellum.
4 Quantity Sand and gravel; diatoms.
5 Quantity Sand and gravel.
6 P. lac. One Odd pieces shell; sand and mud.
7 Owenia fusiformis, P. lac. Brittle-star remains: sand and mud.
8 O. fus., P. lac., Travisia oleus Several Two, and remains Starfish; isopod.
9 O. fus., P. lac. Quantity Sand and gravel.
10 P. lac. Sand and mud.
11 O. fus., P. lac. Small quantity Sea-mouse; sand and mud.
12 Traces worm-cases Remains Two Sand and mud.
13 Tubes P. lac. Sand and mud.
14 Traces worm-cases Quantities Remains Sand and mud.
15 O. fus., P. lac. Sand and mud.
16 Sand-tubes P. lac. Quantity Several
17 Traces worm-cases Quantity Sand and mud.
18 Large quantity M. scalpellum; sand and mud.
19 Sea-mouse; sand and mud.
20 P. lac. Small quantity Remains Diatoms and sand.
21 Small quantity Remains Sand and mud.
22 O. fus., ampharelid polychaetes, Echiurus noiae-zealandiae? E. unicinatus Isopods.
23 Ampharelid polychaetes Quantity M. scalpellum.
24 P. lac., T. oleus One Sea-mouse; isopods; Psamnobia lineolata.
25 Remains Sea-mouse.

Twenty out of twenty-five stomachs contained worms or worm-remains. Dr. Benham, noting the abundance of P. laciniosa on the floor of Palliser Bay, writes: “There seem to be great forests of them in that locality.” About 300 sand tube-worms and ampharelid polychaetes were taken from the twenty stomachs, 145 of the latter being from stomach No. 22 alone.

As most of the fish were trawled at the same time as the tarakihi, it may be inferred that at this season the moki frequents parts of the sea-floor covered with the sand or mud most suitable for the growth and development of the various tube-worms which constitute the principal food.

[Footnote] * Echiurus novae-zealandiae; E. uncinatus; Owenia fusiformis; Potamilla laciniosa (with sand-tubes); Travisia oleus.

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Jordanidia solandri (Cuv. and Val.): New Zealand Hake.
Trawled in Cook Strait, April, 1922.

The whole of the stomachs examined, excepting one, contained remains of young Macruronus novae-zelandiae in varying numbers, the one exception containing numbers of worms, probably parasitic (? Ascaris sp.), and one contained also a piece of bivalve shell. In Hawke's Bay this fish has been found to be a voracious fish-feeder, * inhabiting water of about 20 fathoms. Out of twenty stomachs about sixty-nine examples of Macruronus novae-zelandiae were extracted. Other food appears to be negligible, and the above records show how great the numbers of the young of Macruronus novae-zelandiae consumed during this season must have been.

Chelidonichthys kumu (Lesson and Garnot) and Lepidotrigla brachyoptera (Hutton): Gurnard.
Trawled in Hawke Bay, April, 1922.

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No. Ampipods. Crabs. Shrimps. Sea-mice. Other Material.
1 Ampelisca sp. Seven Leander sp. Several isopods.
2 Hemiplax sp.
3 Ampelisca sp. One Six
4 Hemiplax sp.
5 One One
6 Fragments
7 Two Hemiplax sp.
8 Hemiplax sp. Six
9 (Stomach empty.)
10 Remains
11 Remains Six
12 Traces of black mud and sand.
13 Several Squilla armata Pieces of shell; sand and black mud.
14 Remains Leander sp. One Pieces of shell; isopod-remains.
15 One Pieces of shell.
16 One Remains Two
17 One Copepod-remains.
18 Remains S. armata Three
19 Remains Two
20 Sand and mud.
21 Two One

I believe most of the stomachs examined to be those of Chelidonichthys kumu, though in some instances I was unable to examine the fishes from which viscera had been saved by fishermen. Chelidonichthys kumu has been regarded by some to be a night-feeding species, but, though I have occasionally found large numbers trawled at night, this is by no means a certain indication. The food indicates a wider range of ocean locality than that of most fishes, food from ocean-floor and mid-waters appearing to be equally mixed. Out of twenty-one stomachs examined, nine contained amphipods or amphipod-remains (Ampelisca sp.) in considerable quantities. Unfortunately, the condition of material prevented determination of the species in this as in many other instances. Five stomachs contained

[Footnote] * W. J. Phillipps, Edible Fishes of Wellington, N.Z. Jour. Sci. & Tech., vol. 1, p. 269, 1918.

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remains of seventeen crabs (Hemiplax sp.), eleven contained twenty-four sea-mice, and six contained shrimp-remains.

Thyrsites atun (Euphrasen): Barracouta.
Trawled in Palliser Bay, March-April, 1922.

Of twelve stomachs examined, eight contained young Macruronus novae-zelandiae or their remains, one containing in addition several isopods, another several shrimps (Euphausia sp.); of the others, one contained squid-remains, one copepod-remains, and another sea-mice (Aphrodite sp.).

Macruronus Novae-Zelandiae (Hector): Whiptail.
Trawled in Cook Strait, March, 1922.

Four of the five stomachs examined contained young Macruronus novae-zelandiae; the fifth contained small fish-remains (Clupea sp. ?).

Adults averaging 18 in. in length were trawled in 30 fathoms and brought into market on at least two occasions during March, 1922, being sold as whiptail. I have since been informed that small quantities of this fish appear in the market every few years This species was feeding on its own kind, but the record is not sufficient to justify any conclusion; possibly no other food-supply in the shape of young fish was available.

Physiculus Bachus (Forster): Red Cod.
Trawled in Cook Strait, March, 1922.

(1.) One fish (Scorpaena cardinalis); one young of megrim (Caulopsella scapha); considerable number of partially digested worms. (2.) Three half-grown Macruronus novae-zelandiae.

Pagrosomus Auratus (Forster): Snapper.
Trawled in Hawke Bay, April, 1922.

(1.) A few shells (Verconella nodosa) in stomach; thirty-two young of Verconella nodosa; several Verconella valedicta; and two Euthria in intestine. (2.) Remains of octopus only.

Genypterus Blacodes (Bloch and Schn.): Ling.
Seeured in Cook Strait in 150 fathoms, April and May, 1922.

Of the six stomachs examined, three contained remains of Macruronus novae-zelandiae two contained fish-bones, and one was empty. It is probable that in rising to the surface much of the food of the ling is ejected from the stomach. Practically all stomachs of ling were much infected with parasitic worms. Two contained the cestode worm Bothriocephalus sp., or some subgenus. All contained nematodes which appeared to be a species of Ascaris. Three had the intestine infected with a species of Taenia, which in one case was over 3 ft. long.

Partly digested material is very difficult to handle and more difficult to identify, yet here and there one comes across startling evidences, which may not otherwise be secured, of the occurrence of individual species in unprecedented numbers in certain localities. The two most striking instances noted here are the enormous shoals of Macruronus novae-zelandiae

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in Cook Strait during the season when most of these fish were trawled, and the great forests of Potamilla laciniosa which cover the floor of at least part of Palliser Bay in April. The record of such facts amply justifies time expended on this research.

Among material supplied, Dr. Benham was fortunate in finding one polychaete apparently new to New Zealand, and no doubt many new species of the future will be brought to light by similar methods of research.