The lightfish, Maurolicus muelleri (Gmelin), is a cosmopolitan
sternoptychid fish most abundant near continental shelf-slope breaks and rare
in the open ocean. Recent studies have documented dense populations on
seamounts of the South Atlantic and North Pacific. At Southeast Hancock
Seamount, a small guyot in the central North Pacific, M. muelleri populations
are mainly composed of juveniles. Seasonal length frequencies suggest that
recruitment at sizes greater than 20 mm standard length (SL) occurs principally
in spring and summer months, with growth over summer and fall coincident
with decreasing abundances. Mature fish in reproductive condition occur in
winter months but do not survive to the following spring; they also may be too
few at this small seamount to support annual recruitment. Potential sources of
additional recruitment include populations at several larger seamounts in the
southern Emperor group and also the large populations around Japan. Advection
of eggs and larvae in the Kuroshio Extension may provide recruits for
dependent populations at the seamounts. Mean current flow and satellite-tracked
drifters suggest a transit time of 100-200 days from the coast of Japan
to the region of the seamounts; estimates of age at length suggest that smaller
fish have similar ages at recruitment. Gill-raker counts, however, differ between
Japanese and seamount populations. We suggest that the southern Emperor
Seamount populations serve as the source for replenished annual recruitment to
the small population at Southeast Hancock Seamount
