The Cross Dressing Lates Calcarifer
Posted by Meggs | Fish Life Cycle Posts | Posted on February 23rd, 2008
The barramundi always brings a smile to an angler's face!
Over the next few weeks I will feature posts concerning the life cycles of various Northern Australia fish species.
The major reason for this is that I am a strong believer in the old adage to catch a fish you must first of all think like a fish and know their habits. Some may say the real reason is that our Fishing and Reef Tour Specialists (F&RTS) team are heading off to Weipa in May and a little prior research may come in handy.
Of course, a great pointer to the habits of the fish you are targeting is to take a good look at their life cycle.
This week we’ll discuss the Barramundi or “Lates Calcarifer”.
Well known in the tropical Northern Australia rivers and estauries the Barramundi is said to prefer slow moving or still muddy waters but may also inhabit nearby reefs or islands.
Barramundi are pretty versatile as they are both protandrous and catadromous.
What the??
Ok, protandrous means that the fish changes sex from male to female whilst catadromous refers to its ability to migrate between fresh and salt water. A Barra tends to change from male to female once it has reached a length of 90cm, but only if it lives in saltwater.
Lets take a look at how life begins for a typical Barramundi.
During the months of September and March a female will produce eggs (upwards of 32 million in a season!) in salt water marine bays, river mouths or salty reaches of estuaries. This coincides with the coming and duration of the wet season and in fact most of the spawning occurs during October to December.
Interestingly a male Barramundi will breed at least once if not more times before changing sex. Also there is a theory that some Northern Australia bauxite rich rivers stunt the growth of Barramundi and cause early sex changes amongst the resident populations.
When hatched the baby Barramundi (about 1.5mm in length) move into tidal creeks, mangrove areas or coastal swamps that offer protection. They reach a length of 20mm by the end of their first month.
After the wet season the Barramundi migrate upstream to seek fresh water habitats for their first year where they will attain a length of around 300mm. If accessing fresh water is not an option they will stay in the salt water areas to mature.
Growth spurts for Barramundi largely occur through the wet season and sexual maturity (usually as males) happens after 3 to 5 years. During this time they will reach lengths of 600-800mm.
At about 4 years a small proportion of Barramundi will mature directly as females.
When water flows permit, mature fish make their way back to the estauries and salty areas to spawn amongst the resident population of Barramundi.
It is thought that the older, female fish are able to pass on their survival traits and genetics to the young as they are well adapted to the local conditions.
An adult Barramundi can live to over 30 years of age and weigh in excess of 55kg and grow to over 1.5 metre in length but most caught are between 500-700mm. A one metre fish is thought to be around 8 years old.
Small fish and prawns make up most of their diet and as cannibals they have been known to feast on other Barramundi half their own size.
Tagged fish indicate movement is fairly limited along coastlines however they will travel long distances to spawn in estuaries from freshwater river systems. Once such fish was reported to have travelled over 600km.
Sea you later,
Skipper Meggs