Sexual segregation of pelagic sharks and the potential threat from fisheries
Large pelagic sharks are declining in abundance
in many oceans owing to fisheries exploitation.
What is not known however is whether withinspecies
geographical segregation of the sexes
exacerbates this as a consequence of differential
exploitation by spatially focused fisheries. Here
we show striking sexual segregation in the fastest
swimming shark, the shortfin mako Isurus
oxyrinchus, across the South Pacific Ocean.
The novel finding of a sexual ‘line in the sea’
spans a historical longline-fishing intensity
gradient, suggesting that differential exploitation
of the sexes is possible, a phenomenon which
may underlie changes in the shark populations