98 EDIBLE FISHES. 



coastal cui-rents. In the nortliern hemisphere it is now ascertained that 

 the herring* is restricted to those parts of the sea in which the tem- 

 perature is never less than 54", nor higher than 58° Fahr., a i-ange so 

 limited that it obviously must relate to the existence of some delicate 

 maiTae animal that forms the food of the fish. The study of the ocean 

 currents that sweep our coasts is therefore invested mth gi-eat practical 

 interest, as it will enable us to infer from the experience gained in 

 other pai"ts of tlie world, the character of the marine life which stocks 

 our seas. Unfortunately, the data respecting the dii'ection and average 

 temperature of the sea round the coast of New Zealand is still very 

 imperfect, but the results obtained from a series of observations extend- 

 ing over twelve months dui'ing 1868, and made chiefly with a view of 

 ascertaining how far these seas are adapted to the salmon, afford genei'al 

 indications of some value. 



From these observations it appears that the coldest part of the sea 

 round New Zealand is on the south-east coast of Otago, where the tem- 

 perature of tlie surface-water ranges from 48° in winter to 57° in 

 summer, corresponding averages for the atmosphere being 43° to 58°. 

 The cold current thus indicated, which probably exercises a good 

 effect on the quality of the fish besides limiting the x'ange of a few 

 species, apj^eai'S to extend its influence up the east coast as far as Cook 

 Straits ; biit on the west side of the islands the average winter temperature 

 of the sea was found to be decidedly higher, and equal to that experienced 

 6° of latitude further to the noiiih on the east coast. In the extreme 

 south the summer temperature does not, however, rise to a corresponding 

 extent, but on the Avhole there is evidence that the warm equatorial 

 current, which is known to skii-t the east coast of Australia, and has 

 been lilvcned to a southern counterpart of the gulf stream of the Atlantic,t 

 must be dkected against the west coast of New Zealand, tending to 

 equalize the temperature in that region. In support of this view I 

 may mention that while the red whale-feed (Palxemou), and multitudes 

 of Medusoid forms, are seen in summer on every part of the coast of 

 New Zealand, in winter, on the extreme south-west coast during 

 calm weather, the sea is occasionally rendex'ed almost gelatinous 

 over large areas Ijy myriads of Salpre, and among them the large tiibular 

 Pyrosovm, which is properly an inhabitant of tropical seas. In 1863, 

 on 22ud July, I saw the phosi)horescent displays of these gi-eat commu- 



* Richardson, " Yarrell's Fishes," Vol. II., p. 634. 

 + Commodore Wilkes, " U.S. Exploring Expedition." 



