Sweetwater Fishing Forums
General Category => General Discussion => Topic started by: BG on December 28, 2010, 12:40:14 PM
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G'day folks, I am carrying out a search, when the floods recede, for the possibility of Mary River Cod breeding outside the Mary catchment.
If any of you can assist on the following it would be greatly appreciated.
From what I have heard the Murray Cod is such a close relative the appearance and habits should be the same.
Q.. At what size do the adults become breeders.
Q..What size would I expect the young to be feeding away from their mother.
Q.. Could I expect their appearance to be the same at 100/150 mm as it is at the adult stage.
If not what could I expect to see.
I have a few ideas on methods on capturing the young without harm but I would be grateful for any advice on this also.
Thanks in advance if you folks can assist in this. You can be sure I will report on any success.
Regards Gordon
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If they are breeding anywhere, it will be in the Stanley, perfect conditions. Hard to tell because of stocking efforts though.
Remember you cant target Mary cod except above dams that are stocked with them.
From what I have heard Mary's like cleaner water, otherwise pretty much the same conditions for breeding.
As the minimum size for Mary's is 50cm, I'd suspect they would be capable of breeding around 45cm.
If Steve (elops) wanders along he will have definitive answers for you, he is quite knowledgeable on them.
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It will be up the Stanley and I will be cross checking sizes against recent releases.
Regards Gordon
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G'day Gordon,
As Andrew said Mary's are no take and can only be targeted in stocked impoundments and upstream.
They reach maturity at approx. 5 years with size most likely depending on habitat.
The male guards the nest, even against the female with often fatal results in the confines of hatchery ponds. With larvae dispersing quite soon after hatching and begining feeding in 5 to 7 days on zooplankton, daphnia or any micro foods available.
At 100/150mm are obviously Cod.
With stocking recruitment is hard to determine, though with the demise of the Gerry Cook Hatchery and the cessation of riverine stocking any sub 200 mm fish encountered outside of the limited number of impoundments stocked in 09 would most likely be from natural recruitment.
F1 stocked fish do breed, pic is of an egg from a pair of NPD fish. Will add some more pics of juvies later when on computer at home on laptop atm.
Smallest fish I have encountered was 27cm in the Stanley last year. Probably the best source of info regarding sizes would be Tom Espinoza at DERM who is currently doing a genetic study.
cheers,
Steve.
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I had best start taking photos for ID as I have seen some 40/50 mm fish that may be worth checking out. I will have the time for this but not the knowledge.
Thanks fellas
Regards Gordon
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Does anybody know what happened to the Mary River Cod Recovery Program?
Is the species increasing in number in its native habitat?
and how successful have restocking programs in other area's like the albert, logan and coomera?
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Does anybody know what happened to the Mary River Cod Recovery Program?
Is the species increasing in number in its native habitat?
and how successful have restocking programs in other area's like the albert, logan and coomera?
The MRC Recovery program may be dead in the water. Was a federal program that is out of dosh.
The Gerry Cook Hatchery has been funded by a combination of local councils, State Govt, stocking group & other donations. With another failure this season the future funding is in serious jeapardy for the future it seems. Cold feet seem to be growing among supporters due to local political BS regarding site management, policy & proceedure. One or two key persons walked away due to personal issues, a crying shame..... :walkplank
Only future surveys will tell if this species has established / re-established in those river systems outside (and inside) of the Mary River where MRCs have been stocked. Some fish have taken for sure; recreational angling shows them up on a regular basis, but are they successfully reproducing???
The reasons for the original demise of say the Brisbane River Cod have not all been addressed. Weirs / dams blocking migration, altered flow regimes, cold water pollution from dams, cleared riparian vegetation, desnagging, livestock caving in banks, introduced pest fish..... the list goes on for the problems this iconic species faces.
Cheers,
fitz..
EDIT
Below is a picture taken on the upper Brisbane River, up past Linville. Cleared banks are endemic, cattle permitted to graze into the water, swim across, cr@p in the water & cave in the banks even more. What chance do our native fishes have? We can restock as many as we like, but without suitable habitat, there's little chance of the cod being able to re-establish. NOTE - that farmer brown is content to run a fence across the river at this crossing making kayak / canoe access dangerous, but obviously cares little for the river. The river is just a resource to be exploited for self gain. The scenario is repeated throughout this & many other river system. >:(
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Its good to see there is interested parties out there.
Thanks folks. As for my time frame, once this wet has eased and the Stanley has settled to a gentle flow I will get back to it but if the rain ceased tonight it would be 2 weeks before it could be paddled.
It will take time.
Regards Gordon
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Im a local smack bang between the logan and the albert rivers and talk to allot of fisho's getting around and there is "some" cod in one of these systems wich i wont name and will not fish for and deter anyone from fishing for them.
These are very isolated patches of cod and will allways hear of jo blow catching a cod but a good percentage of the time they are pulling your leg. Bass populations in the logan and albert arent what they used to be since carp have arrived on the scene years ago, sometimes you have to walk miles throwing lures on the logan before you find a good honey hole of bass.
As for the albert its not so dire but have noticed a hell of allot of carp all throughout so that doesnt encourage allot of hope for the future of both the albert and the logan. Cattle wading in the logan is starting to create barrages of dirt and sand collapsing in making it very shallow in allot of places when the logan isnt a very deep river in the first place..
Honestly im suprised to see what natives are still left, will do some scouting around after the fast flowing water clears to see what has been relocated.
Steve
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There was a lot of funding for Mary Cod research and breeding (new hatchery) tied to the Traveston Dam project.
With the Dam canned, so is the funding.
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There was a lot of funding for Mary Cod research and breeding (new hatchery) tied to the Traveston Dam project.
With the Dam canned, so is the funding.
Might that just have been a bargining chip ?
Steve
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No, as part of the original environmental deal they were going to extensive stocking of the dam and the river.
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With all the previous discussion my patch of the river would be easy to find but I would like to point out that it is only accessible from private land.
The area I am looking at is fairly unique and the landowners are aware of this so I am keeping them informed of any progress.
For those intrerested in preserving places like this we have 1 to 1.5 k of still water when the Stanley stops flowing, high banks, the only cattle that can get to the water usually drown. We have a little trouble launching the kayaks and it is inaccessible from up or down stream.
If this is a breeding ground like those that have seen it believe it could be then I will work to have it closed up.
Regards Gordon
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With all the previous discussion my patch of the river would be easy to find but I would like to point out that it is only accessible from private land.
The area I am looking at is fairly unique and the landowners are aware of this so I am keeping them informed of any progress.
For those intrerested in preserving places like this we have 1 to 1.5 k of still water when the Stanley stops flowing, high banks, the only cattle that can get to the water usually drown. We have a little trouble launching the kayaks and it is inaccessible from up or down stream.
If this is a breeding ground like those that have seen it believe it could be then I will work to have it closed up.
Regards Gordon
Hi Gordon,
I've got little doubt as to MRC's breeding in the river where you are. It's pristine. you can see the difference it makes having a river fenced off to cattle. :thumbsup
The lingering issue I have is that I'm not convinced that the Brisbane River Cod was wiped out of this part of the river & further up. By stocking MRCs we may well have compromised any BRCs remaining DNA (if there was any difference).
Hence we've been looking for BIG fish for DNA sampling.
If there are no BRCs left & only MRCs, then closing it up is too little too late. If however it is proven that there are BRCs. I would begin lobbying / working towards total closure of the river, land resumptions etc to protect them.
Cheers,
fitz..
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Gary I just dug up some old records of Cod that have been lifted from this patch, 84 cm.
On the fisheries web site they say that 70 cm is the largest that can be expected.
Usually they are around 35 to 40 cm that we see. I didn't know what I had, hey.
Gordon
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Fitz,
Still have those same lingering doubts about BRC, Gordons 84 cm fish brought them on again.
Are there any BRC left ? this unfortunately is not known.
DNA sampling of large fish in the system may prove this.
BRC would be similar to MRC but as they have most likely been seperated since the same geological event which initially seperated MRC from MC (MRC being a subspecies of MC) there would be quantifiable differences.
If in fact if BRC do remain the now adult population of MRC and the most likely presence of MC would result in hybridization and introgression of any subsequent recruitment. This would be very difficult and costly to address and a massive undertaking, unlikely to be considered by the powers that be. Sadly it may be to late.
Have been looking forward to the results of the genetic study being undertaken by DERM.
cheers,
Steve.
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I think you have the clear picture of the history Steve. The landowners have had this property for over 100 years now and their verbal records on the history of fish that have been caught are great to hear.
All been noted by Sweetwater but it probably is just that history.
I have armed myself with several photos of MC and MRC. And 2 of these have been taken from the fisheries fish identification site. If anybody can suggest other examples showing the variation between the 2 please let me know.
Regards Gordon
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"Are there any BRC left ? this unfortunately is not known."
Steve, when the Brisbane Valley Anglers were doing the SMP for the river below Wivenhoe, we asked Alex Hamlyn from the DPI the same thing. he replied that to the BEST of the departments knowledge there were NO BRC in the waters below Wivenhoe, since construction of that dam.
One assumes that they did some electro sampling during numerous river studies done back then, but that doesn't preclude BRC from existing in the Stanley, Upper Upper Brisbane or even the 2 dams for that matter.
As a few have said, maybe the introduction of MRC will dilute the gene pool, of if I remember rightly, they found that if MC & MRC are crossbred, the eggs remain infertile,,,(can't be sure on that, it was a long time ago) perhaps the same is true between BRC & MRC
Brad
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"Are there any BRC left ? this unfortunately is not known."
One assumes that they did some electro sampling during numerous river studies done back then, but that doesn't preclude BRC from existing in the Stanley, Upper Upper Brisbane or even the 2 dams for that matter.
Brad
Full marks to Alex, Brooksy & their teams, however I would think the survey work was limited by accessability. I've done over a dozen full trips down that 60km section of river, there's alot of river they just cant get an electrofishing boat to.
There's a huge cod on one log we've seen a few times in the mid - Brisbane River (Wivenhoe to Mt Crosby section) that's got to be pushing 80 - 100 pound. I've not seen him there for a while tho (hope he didn't adorn the local butcher shop scales)
That fish has got to be pre-stocking, its just too big to get to that size since MRCs were stocked. That or its a translocated Murray Cod as MRCs aren't supposed to grow that big.
Same for one spot in the upper river (above the lake), we spotted a huge cod up there but havent been able catch it to get a sample.
I think the only way to get an answer is to get DNA samples. In the mean time IMHO stocking of MRCs should stop throughout the whole system.
fitz..
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Gary can you get a bunch of the tubes to me soon plus directions on how to use.
I intent to put a few days a week into my patch until we get some results. It would be a shame to catch measure and photograph without taking a DNA sample.
I guess I should be sampling large and very small ? On a brag mat, camera on flash anything else to consider ?
Gordon
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Sorry very busy at the moment.
Cant find Rowland (1985 1993) which has the crossbreeding/hybridisation results. But all Maccullochella species do or have the potential to hybridise
Quote from Simpson and Jackson 1997 "the introduction of closely related cod species into the existing range of Mary River Cod, namely Murray Cod and Eastern cod, is considered a key threat to this species due to the potential for hybridisation". BRC undoubtably would have faced the same threat with a much smaller population if it existed. Maybe Jim or Kurt or somebody better qualified than me would add to this ?
Not likely to be any stocking for awhile Fitz apart from the few fish Russell produces, hopefully the Genetic study is completed by then.
cheers,
Steve.
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Also tagging, to avoid too much double handling.
Gordon
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Personally I would argue strongly against the use of dart or anchor tags in them, far too precious too risk for many reasons. PIT tags inserted by experienced persons into large fish could be justified.
cheers,
Steve.
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are any hatcheries producing MRC at present?
do any genetic samples for BRC exist?
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are any hatcheries producing MRC at present?
do any genetic samples for BRC exist?
Yes, one at Cooroy who is a part timer / hobbyist,
and
No, Qld Museum has no specimens. So officially BRC is a myth. Strong anecdotal evidence suggests otherwise for the Brisbane & its tributaries (Stanley, Bremer, Warrill etc)
fitz..
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Thanks Fitz. As you know, I love my rustwater, but the ozzy freshwater cods fascinate me.
Australian freshwater fish have shown an amazing propensity to speciate, or too at least throw regionally different colour forms, look at the rainbows for example. Its not uncommon for different and distinct colour varieties to come from neighbouring drainages for some species, as you know.
I heard rumours once of a different looking, very dark coloured cod coming from a creek very high in a murray darling drainage. Big river blackfish? or something else? who knows... could have just been BS. Wish I had more details to check it out. Have you ever heard anything similar?
What does the cooroy breeder do with his fish?
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EDIT
Below is a picture taken on the upper Brisbane River, up past Linville. Cleared banks are endemic, cattle permitted to graze into the water, swim across, cr@p in the water & cave in the banks even more. What chance do our native fishes have? We can restock as many as we like, but without suitable habitat, there's little chance of the cod being able to re-establish. NOTE - that farmer brown is content to run a fence across the river at this crossing making kayak / canoe access dangerous, but obviously cares little for the river. The river is just a resource to be exploited for self gain. The scenario is repeated throughout this & many other river system. >:(
Fortunately Fitz, we are not all like that. Here is a photo of the creek (Tinana) at the bottom of my property. Fenced off, weeded, not desnagged, off course water points. Should be mandatory practice. I must say that I get around alot of farms each year and there is more and more of this practice being undertaken.
All the best
Steve.
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G'day fella's. Before this subject passes into the mists of time can you help with some good photographs of M R Cod, large and small so I can look for variations in the ones I lift.
Just click on my name and my email address is there.
There are differences between Murray and Mary and also patten variations between Mary and Mary. If you could also let me know the size of the fish we are looking at where it was caught. The restocking boys will probably point out reasons for these variations.
Thanks in advance for this.
Regards Gordon
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This pic was sent to me in November last year Gordon. Found dead in the Stanley........