Jm. Kalish et al., TRACE-ELEMENTS IN THE OTOLITHS OF NEW-ZEALAND BLUE GRENADIER (MACRURONU-NOVAEZELANDIAE) AS AN AID TO STOCK DISCRIMINATION, Marine and freshwater research, 47(3), 1996, pp. 537-542
Blue grenadier, Macruronus novaezelandiae, or hoki as it is known in N
ew Zealand, spawns at two distinct localities off New Zealand. Earlier
research on morphometrics and on age and growth suggested that these
spawning localities are used by two discrete stocks; however, the rese
arch was not conclusive. Inductively coupled plasma-atomic emission sp
ectroscopy (ICP-AES) was used to analyse trace elements in otoliths fr
om adult blue grenadier collected at the two spawning sites. Before an
alysis, portions of otoliths formed during juvenile and adult life wer
e isolated and these segments were analysed separately. With a cross-v
alidation procedure (jackknife), it was possible to classify correctly
100% of the samples in relation to age (juvenile v. adult). On the ba
sis of the jackknifed discriminant functions, classifications of blue
grenadier in relation to sex or capture locality were not significantl
y different from random. The results are not definitive in determining
stock structure of New Zealand blue grenadier but do provide insight
into the application of otolith trace element chemistry in studies of
stock structure.