New Zealand Journal of Marine and Freshwater Research abstracts
Macroscopic intersexuality in salmonid fishes
M. T. KINNISON
Department of Biological Sciences
Gilman Hall, Dartmouth College
Hanover, NH 03755
United States
email: Michael.Kinnison@Dartmouth.edu
M. J. UNWIN+
National Institute of Water & Atmospheric
Research Ltd
P. O. Box 8602, Christchurch
New Zealand
email: m.unwin@niwa.cri.nz
F. JARA
Laboratorio de Ecologia Acuatica
Casilla 1060, Puerto Montt
Chile
email: fjara@computacion.uach.cl
Abstract The occurrence of individual salmonids with
macroscopically identifiable, simultaneous male and female gonads is an
uncommon reproductive disorder. Individual specimens have been described, but
no larger synthesis of the condition has been made. We first describe two
simultaneous intersexual Pacific salmon (
Oncorhynchus spp.) specimens,
encountered during rearing operations in New Zealand and Chile, confirming that
the phenomenon occurs beyond the natural range of the genus. A review of these
and other isolated specimens within the Salmonidae (
Oncorhynchus,
Salmo,
Salvelinus,
Coregonus,
Thymallus) suggests
that the disorder takes at least two distinct anatomical patterns, which we
call lobular and mosaic. These are consistent with differences in either the
degree or onset time of aberrant development from protogynous or neutral
gonadal primordia. The disorder has a low natural incidence (one in several
thousand), but the extensive use and study of salmonids makes it likely that
natural macroscopic hermaphrodites will be encountered regularly. Isolated
specimens have been attributed to environmental contamination, but their
widespread occurrence suggests they are primarily a natural phenomenon.
Keywords Salmonidae; hermaphrodite; intersexual; gonads
+Corresponding author.
M99046
Received 28 July 1999;
accepted 28 September 1999
PDF file of entire paper: medium quality (1569K); (scanned from paper original: notes about this process)
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