yellowfish breeding update...

[Ryan Weaver]

Hi guys. There was a thread running a while back asking about yellowfish breeding programmes. I promised a response on the latest re yellowfish breeding programmes and here it is from Pierre de Villiers who used to breed with yellowfish:
"In general there is very little capacity out there and we did not want this
kind of work going wrong.

There is the question of genetics. Where should a farm get broodstock from
and where can they stock if they have broodfish from one river? It is
therefore easier to collect from a catchment for a person in that catchment.
This is when fish are plentiful.

In the case of scarce fish you can breed them because there is already very
few left so there is no choice = Western Cape spp.

They take a long time to get to angling size and people get impatient
waiting and stock Bass."

[Scythe]

I'm very curious myself as I take a bit of an interest in breeding fish.

(My vleikurper just had another batch of about 300 odd wriggly little squirmies and in about 2 months time I should be able to put another batch of 150 odd 3cm fish back into the Moreleta)

My questions :

1) How would you go about obtaining brooding stock. Would you simply proceed to net an area and take breeding size/age fish and how would you ensure you obtain a number of viable cock and henfish ?

2) How would you actually breed them, naturally in empoundments tailored to their typical breeding habits or the more artificial stripping of eggs from ovulating females and then impregnating with sperm gathered in same manner ?

3) What would be acceptible fare ito eating habits, would you feed them pellets and other 'synthetic' foods or use more natural items such as live bloodworm, shrimp, filamentous algae etc ?

Probably off the topic of your original intent with the post though, don't blame me for being curious

[Ryan Weaver]

Hi Scythe.

Not a worry, I'm mad about collecting and breeding fish too and we've got quite a collection here at the Jonkershoek CapeNature aquarium.

Firstly I think you'de need permits from CapeNature or the relevant authorities in your area. I know yellows don't necessarily become ripe in captivity and you'd probably need to use a hormone feed to start the spawning, thereafter the stripping process I should imagine would be much the same as with Trout. I find natural food is always best, especially daphnia for young fry, it depends if you're producing a small amount for interest or a huge amount for the market (where it would be more sensible cost wise to use synthetic feeds).

Hope this helps a bit

[Scythe]

Hi Ryan,

Thanks for the reply. I know about the lisencing/permitting situation and the moratorium on the movement/stocking of Yellows. I speak to Grant at the Hartebeespoort Aquarium often enough about it as I love YellowFish in all their flavours and envision one day having at least LS and SS in the dam in front of my home on my small holding/farm outside PTA.

(Did I mention that I still have to build the dam, habitate a running section of water over gravelly stub strate, establish biotic activity, implement a basic food chain, ensure proper filtration and waste handling though biological and physical means via the creation of a small wetland type system ... oh and ... let's not forget ... get the small holding first ?)

Mostly my initial thoughts/questions were aimed at getting a clear picture in my own mind as to how such an activity would be approached if, worst case scenario, the future survival of YellowFish depended on it.

Needless to say, it's a mind boggling effort and I truly hope we ever have to get to that point. I pray that through the efforts of the YWG, FOSAF, passionate people like Keith Wallington, Turner Wilkinson and every single fly fisher who debarbs, stays off the spawning beds and practises good C&R that the pleasure which is the Vaal and other water systems like the Vaal remain accessible (and moreover ... fishable) ad-infinitum.

Help a Vaalie here ... whereabouts is the Jonkershoef Aquarium starting from CapeTown ? I have some business in the area in the New Year and wouldn't mind setting aside some time to come take a peek.

[Nepptune]

Scythe

The Jonkershoek Reserve is just through Stellenbosch....Here is a link to the map:

http://www.jonkershoek.com/maptoflyfishery.html

Nepps

[Barbus13]

Anybody got an idea if the breeding program is still in full swing at Gariep Dam for SM&LM?

[deewy]

An old tread i know, but it would be interesting to find out what happend in the last 2 years.

[poppernel]

Hi Ryan,

Thanks for the reply. I know about the lisencing/permitting situation and the moratorium on the movement/stocking of Yellows. I speak to Grant at the Hartebeespoort Aquarium often enough about it as I love YellowFish in all their flavours and envision one day having at least LS and SS in the dam in front of my home on my small holding/farm outside PTA.

(Did I mention that I still have to build the dam, habitate a running section of water over gravelly stub strate, establish biotic activity, implement a basic food chain, ensure proper filtration and waste handling though biological and physical means via the creation of a small wetland type system ... oh and ... let's not forget ... get the small holding first ?)

Mostly my initial thoughts/questions were aimed at getting a clear picture in my own mind as to how such an activity would be approached if, worst case scenario, the future survival of YellowFish depended on it.

Needless to say, it's a mind boggling effort and I truly hope we ever have to get to that point. I pray that through the efforts of the YWG, FOSAF, passionate people like Keith Wallington, Turner Wilkinson and every single fly fisher who debarbs, stays off the spawning beds and practises good C&R that the pleasure which is the Vaal and other water systems like the Vaal remain accessible (and moreover ... fishable) ad-infinitum.

Help a Vaalie here ... whereabouts is the Jonkershoef Aquarium starting from CapeTown ? I have some business in the area in the New Year and wouldn't mind setting aside some time to come take a peek.

HI Scythe,

I think Clarias could give you some very good info here.

An old tread i know, but it would be interesting to find out what happend in the last 2 years.

Sure would. How do trout and yellows get on together in stillwaters?

Dave

[Herman Jooste]

HI Scythe,

I think Clarias could give you some very good info here.



Sure would. How do trout and yellows get on together in stillwaters?Dave

Bloody well it would seem. A good buddy who does not lie, spent this weekend at a venue that I introduced hom to. He got a 3.3kg sm + 6 other rats + mices, a 2.7kg Rainbow and 5 other r/b in the same stillwater.

This dam was last stocked 7 years ago, with trout and SM yellows. No body must try and tell me that the two species can not co-exiat in the same water.

[clarias]

No reason why they shouldn't occur together...if stocked in the same waters they'd do equally well I"m sure.

Stumbled across this thread- caught my eye. Thanks Poppernel, I don't have too much knowledge on the subject, but I'll see what I can add. Unfortunately I miss a lot of these more obscure but interesting threads, as I don't often get a chance to browse, and these threads are rapidly replaced/shifted down by the more standard 'what fly for...' threads. Poppernel, won't you do me a favour and in a PM refer to me to any threads where I may be of assistance. I'm not going to be on often during the vac. Thanks...but back to the issue at hand.

I'm not up to date with what's going on at the Jonkershoek and Hartebeespoort Hatcheries, but I'm sure there are other forumers in the know. Wasn't Harties at one stage spawning LMs? I'll also ask about Gariep, didn't know there was a hatchery there.

The Lydenburg hatchery of the Mpumalanga conservation authority has been going through a lot of ups and downs, mostly downs, through the last years. Originally a MASSIVE trout facility that saw to all the state rivers and dams in the forestry areas and mountains being stocked...even the river that runs through the town was regularly stocked at one stage...back when you could purchase an angling licence for trout waters. Now they still do a bit of trout for job creation interests and such, but most of the dams are dry.

In past years they did most of the yellowfish spawning work, trying to create hybrids in order to 'improve' them. Not sure where they stocked these hybrids, but they certainly caused a headache trying to identify any yellow that comes out of the local river! Luckily the new anti- translocation rule shows they've come a long way in terms of the conservation of genetic diversity...
I think there are genetic studies being done on at least the vaal species, which should give interesting results...SAIAB (South African Institute for Aquatic Biodiversity) only recently got a fully kitted genetics lab, so watch this space for interesting new findings! http://www.saiab.ac.za/

The artificial breeding of yellows seems to have been done, experimentally at least, for most species. The way it was done in Lydenburg was to have rocky areas at the inflow. Ripe fish would move to this part of the pond where they would be netted. (The fish shouldn't have a problem developing eggs at the right time of year and with the right feeding, but naturally spawning them would be difficult without the right natural conditions.).
The fish would then be taken to the hatchery where the final stages of the gonad ripening would be stimulated with the injection of hormones (for more info on the hormones and processes related to this, you would have to be seriously interested in aquaculture- this would be a good start, even for anyone with an interest in aquaculture: the South African Aquaculture Association http://www.aasa-aqua.co.za/ .).
Once the hormones have loosened the eggs and sperm, the eggs are gently stripped from the females (more like carp spawning than trout). Same for the male. I think a lot of the problems came with the fertilized eggs. In Lydenburg at least, trout trays (designed to simulate gravel beds) were used with some success. I'm sure further research (more interest needed, financial and economic) would vastly improve on this stage of the cycle. No idea how the young are raised, will find out this week though, where we'll be taking care of wild-caught SM and Moggel fingerlings for growth studies.

I think there is a lot of scope for breeding yellows artificially, both for conservation and stocking into appropriate areas as angling fishes in dams. A lot more research is needed though into making this viable, and sadly a lot more funding, interest, incentive and some repairs to government frameworks are needed.

For those REALLY interested (Scythe?)...here is a complete reference list from someones study (not sure who's, only the reference section came up in the search. Its from some work that UJ did, that university does quite a bit of aquaculture research up in Gauteng). Anyway, if you see any literature that interests you, type it into Google Scholar, and you should be able to access some of the original documents...

http://ujdigispace.uj.ac.za:8080/dsp...%20Revised.pdf

Incidentally, when do LM spawn naturally? Is it at the same time as the SM? I've been wondering what the impact, if any, of people in the rapids would have on their spawning. The SM don't seem to mind, but the fact that LM are so much larger and scarcer, makes me wonder whether they can handle the disturbance or whether they prefer a little privacy? This would be especially difficult if they spawn at a different time from the SM (when people generally stay off the spawning beds, I hope). What do you guys think? I wonder whether anybody has ever looked at whether an LM individual will spawn every year, or only every second year, or even 5?
One never knows with large, long-lived species. They take quite long to build up the resources for spawning, but how long?

Anyway, before I break the server...better be off to bed, off to work tomorrow to prepare for the baby yellows. Exams are over, YES!!!