Km. Bailey et al., INTERANNUAL VARIABILITY IN GROWTH OF LARVAL AND JUVENILE WALLEYE POLLOCK THERAGRA-CHALCOGRAMMA IN THE WESTERN GULF-OF-ALASKA, 1983-91, Fisheries oceanography, 5, 1996, pp. 137-147
Interannual variability in growth of larval walleye pollock Theragra c
halcogramma was examined from 1983 to 1991 and of juveniles from 1985
to 1990. ANCOVA was used to assess differences in population growth ra
tes, and an alternate method was developed to examine variations betwe
en annual length-at-age data and average 'expected' values over differ
ent age groupings. For larvae, the years 1986, 1981, 1989 and 1990 had
higher than average length-at-age, and 1988 and 1991 had lower than a
verage values. Relationships between growth and SST and larval density
were not clear. A tentative relationship between copepod nauplii abun
dance and larval length-at-age was noted. The consequence of larval gr
owth to larval mortality, late larval abundance or recruitment was not
clear. We conclude that larval mortality rates are highly variable an
d tend to mask effects of moderate variability in growth on later abun
dance. For juveniles, 1987 had significantly lower than average length
-at-age and 1988 had higher than average values. Although there are fe
w years of data, they tend to support the importance of juvenile growt
h in the recruitment process. Conditions for the large 1988 year class
are documented and discussed, including warm SST, calm winds, relativ
ely low larval growth rates, low abundances of potential predators on
larvae, low larval mortality rates, and high juvenile growth rates.