F-13 



A more detailed examination of the growth characteristics indicates that this hi^ figure 

 for daily growth increment may not be totally unexpected. In his analysis of growth in E. 

 triacantha , Baker (1959) suggests that the larger size of E^ superba is reached by a longer 

 period of growth rather than by a faster average rate. Althou^ at first sight this conclu- 

 sion appears to be at variance with the calculated rates of Mauchline and Pisher, whan consid- 

 ered in relation to season the similarities become apparent. The percentage increase in 

 length during each month for the two species Ej_ superba and JE^ triacantha has been plotted 

 in Fig. 6.6 and the seasonal changes divided up into a series of growth stanzas leading to a 

 first spawning. The changes occurring are tabulated in Table 6.2. 



The difference in the spawning season of the two species means that by September or 

 October, Ej. triacantha larvae are twice the length of _Ej, superba larvae and it is only in the 

 second growing season that Ej_ superba become larger than Ej_ triacantha . Bearing in mind that 

 the _Ej. superba were only present for the last part of the productive season stanza C is 

 effectively the first production season that the young Ej_ superba will experience. This is 

 in effect the equivalent to stanza A for K. triacantha . Plotting growth during stanzas A and 

 B for Ej. triacantha with those of E^ superba for stanzas G and D (Fig. 6.7) show how similar 

 growth is for the two species during this period. 



Table 6.2. Subjective analysis of growth stanzas in Fig. 6. 7 leading to a first spawning in 

 E. superba and Ej_ triacantha 



Althou^ pre iding some evidence in support of the originally published growth curves 



this evidence shot ? 

 mi^t be expected 

 follow. Secondly, 

 (normal for Ej_ triac 



not be considered conclusive for several reasons. Firstly althou^ it 

 ^t similar species should grow in a similar way this does not necessarily 



account has been taken of growth by larvae resulting from the early 



tha) spawning in _E^ superba . 



The information related to growth in Ej_ superba is summarised in Table 6. 3. 



