Kp. Severin et al., ELECTRON-MICROPROBE ANALYSIS OF JUVENILE WALLEYE POLLOCK, THERAGRA-CHALCOGRAMMA, OTOLITHS FROM ALASKA - A PILOT STOCK SEPARATION STUDY, Environmental biology of fishes, 43(3), 1995, pp. 269-283
The incorporation of dissolved oceanic constituents in the otoliths of
fish has potential as a chemical tracer for reconstructing the early
life history of marine fish. Wavelength dispersive spectrometers on an
electron microprobe were used to measure Na, Mg, P, S, Cl, K, Ca, and
Sr concentrations on the outer margins of 57 juvenile walleye pollock
, Theragra chalcogramma, otoliths from five locations in the Gulf of A
laska and Bering Sea. Discriminant analyses that used various combinat
ions of Na, P, K, Sr, and fish standard length and/or age showed that
60-80% of the samples could be assigned to the correct capture localit
y. While the concentrations of some of the measured elements correlate
d with standard length or age of the fish, there are measurable differ
ences among localities when concentrations are length or age corrected
, mainly clue to differences in Na and K concentrations. Elemental com
position of otoliths potentially could be used to assign fish from a m
ixed stock fishery to original stocks, information that is greatly nee
ded for the effective management of fish stocks.