Life Cycle of the Barramundi
By Bob Ives
You may have told your children that the stork brings Barramundi. Of
course, that’s not the case, but it is a cute theory. But in actuality
it’s much more complicated than that.
The Barramundi holds a very important place in the food chain. Not only
are they great for sport fishing, but they are good for eating and they
supply food to a lot of people. Therefore they have great recreational
value, tourism value (for those coming into Australia to fish for them),
and commercial value in the markets
Barramundi typically live in streams and estuaries in both subtropical
and tropical areas, ranging from Ashburton River in central coastal
Western Australia all the way to the Mary River in southern Queensland.
They are partial to slow moving muddy waters but adapt well to brackish
waters near shore reefs and islands.
However, the do have quite an intricate life cycle. They like freshwater
but do migrate to salt and brackish waters to breed. They move
downstream to breed (especially with the help of floodwaters) because
high salinity is required to fertilize the eggs and keep the larvae
healthy.
Breeding normally begins after the first heavy rainstorms before the
main wet season, which runs from mid-October to January. Without the
flood waters to help them move downstream, baby Barramundi may be eaten
by the larger ones, and this hurts the population in that particular
land locked area.
If all goes well and the Barra is allowed to grow normally, it will
reach 300 mm in the first year after the larvae stage. At that time they
move into estuary and freshwater. It then grows to a sexually mature
sub-adult at about 3 years (up to 580 mm) and an adult at 4 years (690
mm). At 6 to 9 years they will grow to about 850 to 1000 mm and live to
be around 25 years old or more. By now they have learned to live in both
fresh and saltwater.
Probably the oddest thing about a Barramundi is that they change sexes
after breeding. Males will breed one or more times, but then will change
into females. Usually the larger the Barra, the better the odds are that
it is a female. This is a built-in self-preservation genetic feature the
Barra has developed – a ‘survival of the fittest’ thing because these
large females are capable of creating more ‘stronger’ Barras.
Tracked Barramundi that live along the coastline tend to not move to far
from their ‘home base’, but those in freshwater are likely to wander far
off from ‘home base’ for mating purposes. |
