Re: River Levels
Posted: Fri Feb 10, 2017 10:41 am
I’m taking a risk of getting Nomad to the point of no return with some more ‘dirty’talk.
Firstly, we must acknowledge we know very little about the river ecosystem and its function.
Having said that there has been 100 different species of fish identified so far in the Daly River catchment, all of them native to the system, this is rare in itself.
It is believed that some of these fish spawn in clear fresh water, others in marine or brackish water. While others may spawn in fresh water but require the eggs to hatch in salt water before returning as fry to freshwater.
It is unlikely that fish spawn in the fast flowing turbid water that’s going past my kitchen window at around 12klm an hour as I type this.
The number of species that can freely move between fresh and salt water is probably low, Barra have this ability. This enables them to travel on to the flood plains and return to tidal water at will.
The annual migration of Barra in the river is driven by reproduction and feeding urges, the Cherabin appear to be a significant influence on this migration.
The upstream migration from the salt to the fresh water of immeasurable numbers of newly hatched Cherabin is undoubtedly a key driver of other fish species to spawn and migrate, providing a food source for the fishes, there is an informative paper on this; http://www.nespnorthern.edu.au/2014/07/ ... -survival/
I have observed this migration by Cherabin and a number of other fish fry in vast numbers, it seem to happen once the river falls a bit and the flow rate decreases considerably
The run off fishing is a matter of concentrations of predators and prey, anglers are part of the predator class as we target other predators (Barra) that are concentrated in locations where prey is being concentrated by the force of water into ever diminishing places to swim in.
This all happens every year, however the rain fall and river conditions in height and duration of flooding has a significant influence on the all the life within the river and the ability to reproduce successfully and survive.
As side note we should consider the devastating effect the cane toad has had on the environment and the disruption it has caused to the food chain, and don’t get me started on MT TODD gold mine!
Firstly, we must acknowledge we know very little about the river ecosystem and its function.
Having said that there has been 100 different species of fish identified so far in the Daly River catchment, all of them native to the system, this is rare in itself.
It is believed that some of these fish spawn in clear fresh water, others in marine or brackish water. While others may spawn in fresh water but require the eggs to hatch in salt water before returning as fry to freshwater.
It is unlikely that fish spawn in the fast flowing turbid water that’s going past my kitchen window at around 12klm an hour as I type this.
The number of species that can freely move between fresh and salt water is probably low, Barra have this ability. This enables them to travel on to the flood plains and return to tidal water at will.
The annual migration of Barra in the river is driven by reproduction and feeding urges, the Cherabin appear to be a significant influence on this migration.
The upstream migration from the salt to the fresh water of immeasurable numbers of newly hatched Cherabin is undoubtedly a key driver of other fish species to spawn and migrate, providing a food source for the fishes, there is an informative paper on this; http://www.nespnorthern.edu.au/2014/07/ ... -survival/
I have observed this migration by Cherabin and a number of other fish fry in vast numbers, it seem to happen once the river falls a bit and the flow rate decreases considerably
The run off fishing is a matter of concentrations of predators and prey, anglers are part of the predator class as we target other predators (Barra) that are concentrated in locations where prey is being concentrated by the force of water into ever diminishing places to swim in.
This all happens every year, however the rain fall and river conditions in height and duration of flooding has a significant influence on the all the life within the river and the ability to reproduce successfully and survive.
As side note we should consider the devastating effect the cane toad has had on the environment and the disruption it has caused to the food chain, and don’t get me started on MT TODD gold mine!