While a single observation of multiple mating is adequate
to reject strict monogamy within a species, it is much more
difficult to conclusively reject the possibility that polygyny
occurs at low frequencies in sampled populations. Assuming
that the frequency of monogamy is equal in all populations
sampled here, the observation of strict monogamy
in a random sample of 12 seahorse males indicates that at
least 78% of individuals in each population mate monogamously
(P = 0.05). On the other hand, if polygynous mating
behaviour is rare and restricted to only 2.5% of individuals,
as in the pipefish S. scovelli (Jones & Avise 1997), a sample
size of 115 males would be required to detect polygyny with
a probability of greater than 0.05, a number which is both
practically infeasible and ethically questionable given the
current conservation status of seahorses. While the possibility
of a low frequency of polygynous individuals cannot be
entirely ruled out in H. abdominalis, it is nonetheless clear
that monogamous reproduction dominates in this species.