MARINE NATURE NOTES

Otago Daily Times, Issue 21976, 10 June 1933, Page 19

MARINE NATURE NOTES

Written for the Otago Daily Times By David H. Graham, F.Z.S. \ FROSTFISH. Frostfish can well be called one of New Zealand’s mystery fishes. We have very little information about its habitat, its food, or its breeding habits. We lo know that, as a rule, it comes ashore during cold weather or frosty nights. But there are exceptions to this rule, ns the writer can vouch, for when I was in the Bay of Plenty it came ashore at all hours of the day or night. The frostfish was the most esteemed fish of the old-time Maori, who called it hiku or para.

The frostfish is closely related to our barracoota and local kingfish, or hake of the North Island. Its name refers to its habit of swimming ashore on frosty or cold nights, but for what reason we are unable to say with any degree of certainty. Each writer on the subject has his own pet theory, but as yet no one has settled or proved the reason of this habit of committing suicide.

For the information of those who have not seen a frostfish I will append a few particulars of its description. The frostfish picked up on our beaches range from three to five feet in length. For some unaccountable reason no small frostfish arc seen. The body is long and thin, ribbon or strap-like in form. There is one dorsal fin along the whole back, containing 100 spines, with small forked but well-developed tail, not. unlike the tail of the barracouta in miniature. This is one of our few sea fish without scales. The lower jaw *is the longest, while the upper jaw is well armed with a row of about 20 to 24 lancet-shaped teeth on each side, those in front being much smaller. Near the front of the upper jaw are two pairs of long flerce-looking fangs; the hinder pair is longer and the left ones slightly in advance. The lower jaw has a single pair of small fangs, with a series of 18 smaller teeth on each side. This description shows that this fish is well armed, and, with its slender body, could apparently slip through the water easily in pursuit of fish and make its approach very difficult to detect until too late. An examination of its jaws will soon prove its capability of holding on to anything it catches. Where the bones of the lower jaw join or hinge will be found a short thick barbel. The colour of this fish is bluish silvery, rather darker above on the back. Past workers on fish state that the frostfish is never taken by hook or by nets, and is only cast ashore at nights, where thei’e is a gentle slope, and where the surf breaks some distance from the shore. My records show, however, that it is taken by trawlers in the Hauraki Gulf during the winter and spring. During my stay at Russell, in the Bay of Islands, in 1928, fishermen there told me of having caught frostfish on long lines with whole small fish as bait. Furthermore, reliable local fishermen have caught frostfish in a seine net in Otago Harbour. On other occasions frost-fish have been seen to swim over the top cork-line of nets while seining. The theory that they come ashore only where the surf breaks off shore is without foundation, as the writer has seen them come ashore in harbours where there is no surf.

One authority writes that he has seen a frost fish on a frosty morning skimming the water in a tortuous course with its back fin rippling in the water. He suggests that it was chasing its prey on frosty calm nights when the sea is smooth, and that, pursuing its victims too near the shore, it is left stranded by the long swell during ebb tide.

Another observer states that he has seen a frost fish deliberately casting itself ashore, selecting a shallow, sandy, beach for that purpose. He thought it must have had parasites, but when examined no such animals could be found on the fish. Nor was the fish blind, and, furthermore, when the observer attempted to turn the fish back to the open sea, it again, after a few minutes, turned shorewards and persisted in going up high and dry as far as possible. A further theory is that , these fish that are found ashore are fish which, haying, produced theip eggs or sperms, are weakened in consequence and burst their air bladder and, coming to the surface and being not able to return to the usual habitat, commit suicide by going ashore. How much of this theory is possible I do not know, but in the many frostfish I have examined in the Bay of Plenty, and in one at Portobello, the air bladders were in perfect condition. Another theory is that the air bladder is distended to bursting point on account of the fish having left its natural habitat at the lower depths of the ocean. In all the other species of fish I have examined with air-bladders so distended, the fish has been floating belly upwards and not able to swim, before it was washed ashore. This is. contrary to the manner in which the frostfish comes ashore. In my experience all the frostfish that swim or are washed ashore are in perfect condition and there are no more than the few usual parasites in the stomach or body cavity. On one occasion only did I find any remains of food; in this instance, only the backbone remained, apparently of a small fish. It has been stated that the frostfish follow the shoals of sprats and in chasing them unintentionally come ashore. In my research on the stomach contents of fish, I have found that few if any sprats , are to be found during those months when frostfish are found stranded on beaches. My experience of frostfish in the Bay of Plenty is that they deliberately swim ashore and become stranded on the sand. On many occasions while travelling along the sandy beaches I have seen them swimming and leaping on to the sand out of reach of the tide. While boating on the Ohiwa Harbour (which is over 400 yards wide) we saw a frostfish swimming for the shore. Pulling after the fish, we saw it purposely leap ashore. Securing it, we returned out to the channel and let the fish go; it-again swum ashore, and we again followed and secured it. This time we pulled further towards the middle of the channel, and on letting the frostfish go we headed it towards the ocean. It at once turned to the shore and again swam and leapt ashore. The water was calm and there were no breakers at this part. As the fish seemed to have made up its mind to commit suicide, we Jecided to let it have its own way and had it for breakfast.

It appears to mo that this fish is a denizen of deep waters, and for some reason it gets out of its usual latitude and is not able to return. The temperature of the water where it usually lives is much warmer than that on the surface, and the fish, not being able to acclimatise itself to the colder water, contracts a form of insanity and deliberately commits suicide by getting out of the water that is too cold for it. Personally, I do not consider these fish feed at all after they lose their usual range, and soon swim ashore, as in practically every instance the fish is in splendid condition, and the stomach empty. The theory that frostfish only come ashore during frosty or cold nights can be exploded, as the writer has seen them swimming ashore at mid-day with the sun shining, but this is unusual. On account of its silvery brightness it is an interesting sight to see this fish like a broad ribband swimming and leaping through the transparent water. The shining whiteness is a thin covering which takes the place of scales, and can be easily rubbed off with the fingers. At one time hundreds of these fish came ashore at Purakanui and were sold to hotels at prices from Is to 2s fid per pound; but fewer are seen now, and no more than a dozen will appear on the market during the winter. The

flesh is considered a great delicacy, and is always in great demand. In England it is called the scabbard fish, as it resembles the sheath of a sword. It is rather common in the Mediterranean and warmer parts of the Atlantic, extending northwards to England, while it is. an occasional visitor to the (jape of Good Hope. A species, a little more attentuated, ‘is found off the coast of Japan at a depth of 340 fathoms. It is also found in Australian waters, and considered to be a deep water fish. To give an idea of its ribbonlike construction, a specimen measuring four feet will not weigh more than four pounds. The ventral or underneath tins are nothing but a pair of scales, and it is from this peculiarity that it receives its generic scientific name of Lepidopus. It would be of great interest to me and useful to science if any of my readers could forward me the stomachs of any frostfish found by them together with any of their observations, which might help to solve the problem of this mysterious fish..