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Volume 88, 1960-61
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Distribution in New Zealand Waters

Present information suggests that about two-thirds of the New Zealand squaloid species have their centre of abundance in depths approximating to the middle region of the continental slope—i.e., 300–600 fathoms. These depths are not worked by commercial fishermen, and only in a few regions around our coasts have they been explored experimentally with trawls or lines suitable for taking fish such as sharks. Consequently the present known distribution of our deep-water squaloid fauna corresponds to the areas where exploration has taken place, notably the eastern approach to Cook Strait and southwards to Kaikoura. Isolated captures of deep-water squaloids in shallower water elsewhere around our coasts suggests that the fauna is not limited to the known areas.

More adequate data establish three predominatly shallow water and shelf species, Squalus acanthias, S. blainvillii and Oxynotus bruniensis. These are all taken by commercial trawlers, S. acanthias in commercial quantities, S. blainvillii sparsely, and Oxynotus bruniensis uncommonly. Squalus acanthias is particularly numerous around the South Island and in Cook Strait, but in the North Island extends only to about East Cape on the east coast, and New Plymouth on the west. Squalus blainvillii has a much more northern distribution, from East Cape northwards on the east coast, and Cook Strait northwards on the west. S. blainvillii is also found at the Chatham Islands, to the east of New Zealand, where its presence shows fairly good correlation with the warm East Cape current trending from East Cape towards the Chathams, and linking the Chathams with the north east region of the North Island, where S. blainvillii also occurs.

Oxynolus bruniensis appears to favour the edge of the shelf and the upper continental slope. Its capture by commercial trawlers is nearly always an indication that they have been fishing in 80 fathoms or deeper. So far O. bruniensis is known only from about Cook Strait southwards to Otago on the east coast. Trawling in 80–100 fathoms or deeper is not uncommon elsewhere round our coasts, and particularly in the north, but has not resulted in the capture of O. bruniensis. The bizarre appearance of this species makes it unlikely that it would be overlooked in trawl catches, hence its southern distribution appears to be established.

The three depth range categories given below are the best approximation that can so far be made as to the depth ranges of the New Zealand squaloids. The species are placed in them according to what is thought to be their centre of abundance

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rather than their maximum range known for New Zealand which is given in the bracketed figures following most species. Many species undoubtedly stray outside these depth-ranges; thus Scymnodon plunketi, Deania calcea and Dalatias licha are commonest in 300 fathoms and deeper, but occasionally stray into very much shallower water. The taking of eight juveniles of Centrophorus squamosus in 200 fathoms, while the adults are known only from deeper water, down to 500 fathoms, may indicate that these deep-water squaloids move inshore to give birth to their young, as do the shallow-water species whose breeding habits are better known.

The two species of Echinorhinus are not classified to range, for although all the New Zealand captures are from shallow water, records of E. brucus elsewhere cover a wide range to about 500 fathoms. Scymnodalatias sherwoodi, known from one stranded specimen, agrees with deep-water species in its uniform dark colour and large eyes. But until more specimens are taken, its habitat can only be conjectured.

Depth Ranges of New Zealand Squaloid Sharks

  • (1) Shelf species (0–100 fathoms).
  • Squalus acanthias
  • Squalus blainvillii
  • (2) Outer shelf and upper slope (80–300 fathoms).
  • Oxynotus bruniensis (25–140).
  • Etmopterus lucifer (100–200).
  • Juveniles of Centrophorus squamosus (200).
  • (3) Middle slope (300–600 fathoms).
  • Etmopterus baxteri (480–780).
  • Centrophorus squamosus (500).
  • Centroscymnus owstonii (420–600).
  • Centroscymnus crepidater (420–500).
  • Scymnodon plunkeli (120–780).
  • Deania calcea (40–600).
  • Dalatias licha (20–480).
  • Depth range not known:
  • Echinorhinus brucus
  • Echinorhinus cookei (35–50).
  • Scymnodalatias sherwoodi.
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