Backyard Aquaponics
A place to discuss aquaponics

OK earlier, on another thread, I inadvertently passed along some second-hand comment about Challenger TAFE and a failure to raise silver perch from hatching through to fingerlings.

I am reliably informed by TAFE personnel that this is not the case and that they were successful.

Please see the letter below and interpret as you will. I will not be posting further to this thread, other than to put put up the photos of the growth progress.

The first lot of photos

and the rest

Hmmmmm, thats kind of defensive.... I struggled to even find the throw away comment you made.

So I wonder if they are going to start supplying on a regular basis? I imagine local breeders would probably be wondering too..

Adding to this, I wonder if this would be feasible when it's of a commercial nature. If it is commercially feasible then why aren't any others doing it I wonder. Or perhaps the overheads and associated costs with doing it indoor make it non-viable in the real world... I dunno, that just raises so many quesitons..

Raising the larvae in ponds is much less labour intensive which is why it is generally done that way. I think you will find that all the local Silver Perch breeders are pretty much 1 man operations where as the TAFE has plenty of staff and students to share the work load of hatching out artemia a few times a day for several weeks.

We saw them in 2009 during a visit, pretty cool setup they have there. I was told at the time that the SP stock was raised as a trial for Golden Ponds and that is where they all ended up. One would think that whether or not raising continues in this manner would have to be dependant on whether the venture was easier and more profitable for Golden Ponds.

Certainly no-one is going to do it this way if it is not economically viable. It does however remove some of the risk of pond culture given you have a controlled environment and this reduced risk would have to be factored into any long term economic calculations. You only have to look at how we are short on fish stock this year due to last sumers weather to see what some of the benefits may be to big suppliers who need to be able to guarantee orders.

Im not convinced that raising the larvae in tanks is more successful. The year that the TAFE had good success in doing it all the growers raising larvae in ponds also raised more than enough fish to meet the demand. This season just gone was a different story as we know but by the sound of it Freo TAFE didnt fare any better. Whether that was because of using smaller tanks or not is anyone's guess.
Interestingly Dr Stuart Rowland (the pioneer of Silver Perch Culture) mentions several advantages of pond culture compared to tank culture. Those being and I quote:
simpler technology, less labour intensive, faster growth rates, fewer disease problems and higher rates of swim bladder inflation.

From the First Feeding SP pic.

Didn't I see this in a movie starring Sigourney Weaver, Tom Skerritt and John Hurt?

we arised silvers from eggs to larvae to fry by the tank method and the pond method 2 years ago. Pond fish were soooo easy and much healthier and bigger at the same age, not to mention soooo much cheaper to raise...
Artemia is a tiresome and tricky process , you have to enrich them in order to get enough nutrients into the fish for really good growth. I would be interested to hear if tafe enriched the artemia or not. Basically given the choice and equipment / infrastructure for both methods and having tried it as a one man band without fee-paying individuals to pay the labour and power bills required to do it in RAS, ponds are the only way I would ever do it again.

Challenger has done a lot of (published) work with enriched artemia Monya....

From your post... what was your timeline from spawn to "fry"... and what size were the "fry"...

Part of the skepticism I expressed, along with the lack of any published data... related to conflicting timelines, numbers and size of "fry/fingerling" delivered to Golden Ponds...

First reports suggested a spawn of 800,000 about end of September.... which is very early... and I wondered about the viabilty of many of the ova that early in the season...

Later posts suggested that the "fry/fingerling" were stocked into Golden Ponds Dec 7th... at around 35mm.... which for a timeline of 50-60 days seemed an astonishing result....

Subsequent information suggested that in fact 63,000 fry/fingerling were delivered to Golden Ponds in September 2009... which would be even more astonishing, both in terms of time of spawn, and growth...

If true the ultimate 63,000 from 800,000 ova would certainly be consistant with the viability of the ova from such an early spawn.... but the claimed growth rates still seem significantly faster than anything I've ever seen reported... even in pond based production...

The information above however suggests 200,000 fish (from the reported 800,000 spawn) were in fact delivered in early December.... but no suggestion of size was made in the above... and forum posts suggest the fish were smaller than the 35mm reported...

It's hard to tell exactly what the scale is in the posted photos...

Even at around 10mm.... 200,000 fry/fingerling in a "couple of 5000L tanks"... would be a significant result... and eagerly embrassed....

While undoubtably a "success".... a 25% survivablty rate... less if in fact the number was 63,000...... one wonders if that represents a "commercial" viability in comparison to pond based rearing...

I look forward to reveiwing the published data...

And to be clear, my posts at the time, and since... weren't made to "denigrate" the TAFE, or bring their "reputation into dis-repute".... Challenger has a deserved reputation for large amounts of significant aquacultural research...

The posts were more a skepticism expressed in relation to the conflicting reports being posted... related to accepted timelines/practices... and the lack of any supporting published data to the contrary...