Pilchard is also called Mohimohi, sardine (wrongly), and Picton herring
This small fish averages 15cm in length but can reach 25cm. It is blue above, greenish on the sides, and silver underneath. There is a row of black spots down each side that distinguish the pilchard from other small pelagic fishes. The body of the pilchard is almost round.
The late David H. Graham in A Treasury of New Zealand Fishes describes fishing off Cape Saunders, Otago, and seeing the following incredible sight. “As far as the eye could see these small fish were swimming in a northern direction, accompanied by flocks of predatory birds, such as Mutton Birds (sooty shearwaters), Cape Pigeons, Gulls and others. They were so abundant that when the launch was moving it seemed as though we were speeding over a floor of silver…” Such were the vastness of the pilchard schools seen in Otago in the 1930s.
Graham found that although pilchard are a pelagic (surface) fish he often found them in the stomachs of commercially caught fish that had been caught in very deep water over 80 fathoms down. He couldn’t say whether the pilchards have dived to that depth or if the deep water predators had come up to the surface to catch them.
Sometimes huge numbers of pilchards were washed ashore in Otago and collected by residents who considered them to be good eating. Graham also reported that in 1900-1902 huge numbers were washed ashore off Oamaru and sold to retailers at 3 or 4 shillings a kerosene case. They retailed at 3d a dozen fresh and 4d a dozen smoked, and were much in demand.
It seems that for the most part pilchards eat small crustaceans particularly in the larval stages, such as crabs and shrimps. It could be that the abundance or otherwise of pilchards is affected by the annual fluctuations of their food supply.
One thing is certain pilchards are preyed upon by barracouta, kahawai and other species. Graham reports large shoals of pilchards around Cape Saunders being set upon by large shoals of the barracouta. The barracouta were forcing the pilchards on to the rocky coastline. They were so abundant that it was no trouble to dip a hand net into the sea and scoop up a full net.
Even in June and October off Cape Saunders, and as far as Puketeraki shoals of pilchards were seen a mile wide and almost continuous in length. All the while the pilchards were bubbling on the surface of the sea as they attempted to evade the barracouta and other fish that were pursuing and devouring them. Barracouta caught at such times were found to contain three or four dozen pilchards in their stomachs.
The vast schools of pilchards are preyed upon by a surprisingly large number of other species: Graham found the following species to have been feeding on pilchards: sevengill shark, tope, smoothhound, spiny dogfish, thresher shark, porbeagle shark, javelin-fish, whip-tail, hake, red cod, megrim, lemon sole, common sole, warehou, groper, kahawai, yellowtail kingfish, snapper, mackerel, and red gurnard. No doubt there are many others!