F. Arrhenius et S. Hansson, GROWTH AND SEASONAL-CHANGES IN ENERGY CONTENT OF YOUNG BALTIC SEA HERRING (CLUPEA-HARENGUS L), ICES journal of marine science, 53(5), 1996, pp. 792-801
Growth rates, hatch-date distributions and seasonal changes in energy
content of larval and juvenile herring (Clupea harengus), the major Ba
ltic Sea zooplanktivore, were studied in a coastal area. The first mic
rostructure (ring) shown in the otoliths (sagittae) was formed at the
end of the yolk-sac stage. The following rings occurred regularly and
showed a pattern corresponding to daily growth rings, as described in
the literature, and we used these rings to age the fish. The average g
rowth rate was estimated al 0.37 mm d(-1) and 0.58 mm d(-1) for larval
and metamorphosed herring, respectively. The overall growth for ail y
oung stages could be described with a fourth order polynomial relation
ship between length and age. Estimated hatching dates were distributed
between March and June. This is earlier than normally assumed for the
northern Baltic Sea and was probably caused by an early and warm spri
ng in 1993. Our data indicate the highest survival for herring spawned
from end of April to the middle of May. In terms of seasonal and year
ly fluctuations in body composition, there was an increase in energy c
ontent from 2200 to 2800 J g(-1) wet weight and 2900 to 4800 J g(-1) w
et weight for larval and metamorphosed herring, respectively, with nea
rly constant energy content during metamorphosis. (C) 1996 Internation
al Council for the Exploration of the Sea