Nehu, Stolephorus purpureus 



A study of populations of the nehu, 

 Stolephorus purpureus Fowler, using variation 

 in vertebral number, was made by Tester and 

 Hiatt (1952) . The study was based on 18 samples 

 collected in seven localities from three Hawaii- 

 an Islands, Oahu, Maui and Hawaii . 



The nehu is characteristically an inshore 

 fish, occurring for the most part in isolated 

 localities where the water is less saline and 

 more turbid than in the open sea. Thus, it is 

 possible that a discrete population of nehu occurs 

 in each baiting area . 



The mean number of vertebrae and the 

 range in means of the several samples from 

 each locality are summarized in the following 

 table: 



might be demonstrated by more extensive 

 sampling and other methods of study. 



Australian anchovy , Engraulis australis 



A study of the populations of Australian 

 anchovy was made by Blackburn (1950). Using 

 differences in average vertebral counts, he 

 divided the Australian anchovy into three groups 

 which he considered distinct enough to be classed 

 as subspecies. These were: 



1 . Engraulis a ustralis australis from 

 Queensland and New South Wales, having a range 

 of 40 to 46 vertebrae and average counts in dif- 

 ferent localities of 43 . 10 to 43 . 99 vertebrae . 

 Average dorsal fin ray counts ranged from 14.07 

 to 14.60. 



2 . Engraulis australis antipodum from 



The data show a striking difference be- 

 tween the mean vertebral number of Ala Wai 

 Canal nehu and those of other localities . The 

 authors point out that the water in Ala Wai Canal 

 is less saline than in other localities and they 

 postulate that the outstandingly low mean count 

 for Ala Wai Canal fish "is probably related in 

 large part to the brackish -water habitat." 

 (ibid .: 68). 



Ala Wai Canal is the only locality in which 

 the existence of a separate stock has been 

 demonstrated. The authors point out that the 

 difference in mean vertebral counts between the 

 other localities could have arisen in random 

 sampling from one statistically complex bio- 

 logical population. However, they do not entire- 

 ly dismiss the possibility that essentially dis- 

 crete units occur in each baiting area, which 



Twofold Bay through Victorian, Tasmanian and 

 probably most South Australian waters, having 

 a range of 42 to 48 vertebrae and means from 

 44.90 to 45.84. Average dorsal fin ray counts 

 ranged from 14.47 to 15.31. 



3. Engraulis australis fraseri from West- 

 ern Australia, having a range of 41 to 46 vertebrae 

 and means from the two localities studied of 43. 12 

 and 43.83 vertebrae. The average dorsal fin ray 

 count in one of these localities was 14.49. 



BlacKburn points out that the number of 

 vertebrae and dorsal fin rays increases toward 

 higher (colder) latitudes. The group he separ- 

 ates as Engraulis australis antipodum occurs to the 

 south of the other two subspecies . Hence, it is 

 possible that the differences found by Blackburn 

 could be due to environmental factors alone. 



68 



