15 DECEMBER 1999
Sent: December 02, 1999
From: Norsk Kveite A.S. <n-kveite@online.no>
To: <AQUA-L@killick.ifmt.nf.ca>
QUESTION:
We are growing Atlantic halibut and have recently faced problems with bacterial infections in the larval gut, causing the larvae to stop feeding and later die. Trials with antibiotics reduces the mortality but it seems like intestine is already damaged when we can observe the problems. The result after treatment is poor growth and 50%+ mortality. Has anyone experience with probiotics or other solutions of the bacterial problems in larval stages of other species?
We are using UV filters on the incoming water and are feeding with
Artemia.
Olav J. Lyngstad
Norsk Kveite A.S.
Eikevaag
N-5314 Kjerrgarden
Norway
Tel/Fax: (+47) 56 14 52 05
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COMMENTS 1:
In response to the problem with bacterial infections in the larval gut of
halibut, have you tried treating the Artemia for ten minutes with fresh
water prior to feeding? If faecal strands are observed, this seems to be
an early indication of bacterial problems forming in the gut, this is when we would treat. The strands go within 24 hours. It seems to work.
Peter_Harvey, SFIA
E-mail :Peter_Harvey/SFIA@fc.uhi.ac.uk
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COMMENTS 2:
Can you elaborate on the rinsing techniques for Artemia-10 minute fresh water bath? Have you actually conducted bacterial counts before
and after rinsing to determine if this procedure rids of bacteria?
I am curious as to acceptable levels of bacteria during the Artemia stage.
Secondly, what is actually happening when faecal strands do appear? Can we assume the larvae are not digesting food due to a colony of bacteria in the gut or the gut has not developed enough to digest food due to bacteria in the gut at an early stage?
People have suggested that if halibut larvae are not taken out of silos prior to 200-210 degree days and given algae (probiotic) to help develop gut and immune system prior to first feeding than, problems will develop with larvae and bacteria at a later date?
From 210-260 degree days-this period is the most important for the
overall long term survival of the fish. It is during this time that the
larvae develop their digestive system. The ingestion of algae plays an
important role in this development. Between 250-280 ddg larvae are not dependant on algae as food. The main purpose of algae at this time is to maintain good nutritional value of the food in the first feeding
tanks and partly to minimize ammonia fluctuations. Feeding strategies,
light levels and water chemistry are crucial during this time. Can people agree with this statement?
Finally, in a case like Olav speaks of: what is a method of treating the larvae?
Danny Boyce
Ocean Sciences Center, Memorial University of Newfoundland
St. John's, Nf., Canada
E-mail: dboyce@morgan.ucs.mun.ca
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COMMENTS 3:
If you:
- rinse your Artemia with fresh water
- treat them with a surface disinfectant (e. g Kick Start 10 mins @ 1:250)
- blast them with UV etc.,
you will certainly drop the viable counts associated with your Artemia.
Possibly by the order of a log or more (e.g. 10^4 CFU/ enriched Artemia to 5 x 10^2 CFU/Artemia).
BUT there will still be a large number of bacteria associated with your
live food because none of the above methods will remove the internal
bacterial loading of the filter-feeding Artemia. Also, one of the
unfortunate things about bugs (from a fish farmers point of view) is that they multiply very quickly - some of the opportunistic vibrios (e.g.
Vibrio splendidus & V. alginolyticus spp.) commonly associated with Artemia, particularly under enrichment conditions, have doubling times of 30-40 minutes @ 20 degrees C. You may have some chance with a cold water species such as halibut, but this effectively means for many cultured species bacterial numbers will be right back to where they were before treatment within a few hours. Also they will be shedding bacteria into the tankwater. As to what the beasts get up to when they are inside your fish we have only a limited idea, importantly it appears that only a fraction of the organisms associated with the live food appear to settle in the larval gut (in halibut and turbot anyway). This means attempting to just reduce bacterial numbers per se may not be the right way forward. Preventing the entry of undesirable organisms / manipulating the flora by addition of 'probiotic' spp. etc. may be a more rational approach.
A lot of this is still just theory and not much use to people trying to
grow small fish here and now. I believe there is a product on the market, 'Hatch controller' at the moment, produced by INVE, that is supposed to address some of the above problems by particularly suppressing the Vibrio blooms associated with Artemia cultures. Unfortunately, I have yet to see anything in a peer-reviewed journal about its effectiveness, only a brief report of 'in house' trials (quite possibly I just haven't found the relevant literature though). Any feedback, either to myself or the list, by the company or people using this product would, I know, be welcomed by hatchery operators in the UK.
David Verner - Jeffreys
Division of Infection and Immunity
University of Glasgow
Glasgow G12 8QQ, UK
Tel: 0141 3306688
Fax: 0141 3304600
E-mail: djeffreys@mblab.gla.ac.uk
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COMMENTS 4:
INVE's Hatch Controller is only sold in Europe. However, INVE
AQUACULTURE, Inc. in Grantsville, Utah (435) 884-3406,
inve-us@inve-us.com, does offer the line of A1 SELCO products that contains the Hatch Controller in an enrichment emulsion that is added at T-0 when incubating Artemia cysts.
I believe the reason for not offering it here in the States is that we (US
Division) elected to use it incorporated with the A1 SELCO line as it
accomplishes the same thing but allows for early enrichment of the Artemia nauplii at the same time. Another reason was we didn't believe it would sell as a stand alone product. Maybe Europe and the interest received now will dictate otherwise.
Howard W. Newman
Inve Aquaculture, Inc
Artemia Task Force Division
E-mail: BShrimp@aol.com
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COMMENTS 5:
Have you considered changing to a freshwater food such as Daphnia or
copepod as an alternative to Artemia? I have been told repeatedly that
bacteria won't transfer from fresh to saltwater.
Barry Thoele
Live Aquatics
E-mail: liveaqua@brainerd.net
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COMMENTS 6 :
I would agree with Peter on the idea of rinsing Artemia with fresh water. We recently carried out a trial at our halibut hatchery in Nova Scotia. We assessed the efficacy of a number of disinfectants in terms of reduction in total numbers of bacteria. We found that freshwater immersion for 30 min was most effective and resulted in up to a log 3 reduction in CFU/ml, without harming the Artemia. On the probiotics, early algae feeding point, I have heard no convincing evidence for this and my view is that we should keep the yolk-sac larvae in clean and relatively sterile conditions for as long as possible until it is really time to feed. To start adding algae or other organic matter to the system before this point is asking for trouble. While live algae, or a good substitute, is absolutely necessary for first feeding of halibut, I am skeptical as to whether it is playing any important nutritional role. We
use the most "nutritionally poor", easily grown algae there are. I think the turbidity is far more important than the nutritional role.
Nick Brown
Marine Harvest McConnell/
R&R Finfish Development Ltd
RR 1 Sandy Cove
Digby
Nova Scotia
B0V1E0
Canada
E-mail: npbrown@tartannet.ns.ca
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COMMENTS 7:
The problem is not "bacteria", but which bacteria. Practical approach to probiotics is to not clean, just rinse, Artemia hatching containers that are providing good results and sterilize all the equipment when pathogens appear. If you have some systems that are still working without problems or put some samples in the refrigerator, you can seed the sterilized systems.
The above crude feedback approach seems to work at our hatchery and
we will go years just hosing down the equipment. We also play some
games with some additives (like INVE -- we don't talk about what is
in them). We don't know the relative significance of operating
procedures and additives, we just know it seems to work without
problems. The additives are designed for water chemistry, and
microbiological manipulation reasons -- probably more black magic
than real science (I do know what we are doing to the water
chemistry, but the impacts on the microbiology are a lot of black
magic which may be real or just luck).
Dallas E. Weaver, Ph.D.
Scientific Hatcheries
5542 Engineer Dr.
Huntington Beach, CA 92649, USA
Tel: 714-890-0138
Fax: 714-890-3778
E-mail: deweaver@gte.net
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COMMENTS 8 :
Try Chloramine T; 30 ppm added to the hatchwater when the cysts are added has been reported to substantially drop bacterial loads.
Steve Newman
E-mail: SGNEWM@aol.com
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COMMENTS 9:
What is the lifespan of freshwater copepods, etc. in saltwater?
Does your company produce them?
Laurel Ramseyer
E-mail: lramseyer@wcs.org
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COMMENTS 10:
I don't have that information; I would however think that it would be
less than 12 hours.
I do have copepod eppiphia collected this fall but I don't have time for
this one myself.
It may be of interest, that it is possible to collect large amounts of
eppiphia of both freshwater Daphnia and copepods in the fall in
Minnesota and elsewhere.
I personally harvested 5# of D. magna and 128+g of Copepod eppiphia just this fall.
Barry Thoele
E-mail: liveaqua@brainerd.net
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COMMENTS 11:
We are now using Artemia cysts from a Russian origin, without
decapsulation but we disinfect the cysts prior to hatch and are also using Hatch controller (INVE) during hatching. We have also been using Great Salt Lake cysts with decapsulation, but the end result in the tanks is the same. The Hatch controller seems to give a better environment, and an easier separation of egg shells / nauplii (but again no plate counts done).
The bacteria will grow up in the cultures in the enrichment phase and
for halibut we are presently using different enrichments, to try to meet
the specific nutritional requirements for halibut larvae. In this case it
would be better to have a kind of probiotic or your own seed of good
Artemia culture that's useful for all kinds of enrichments.
I guess this will be one of the topics discussed at the workshop in
Nanaimo. Maybe some of the aqua-Lers are going there and can inform us more about the topic.
We have been using copepods, mainly saltwater copepods, but to maintain a stable production throughout the year we are trying to leave the copepod track.
The interesting part of these bacterial infections, is that they only
attack a few tanks, like in this autumn season 25% of the tanks were
attacked.
Olav Lyngstad
Norsk Kveite A.S.
Eikevaag
N-5314 Kjerrgarden
Norway
Tel/Fax: (+47) 56 14 52 05
E-mail: n-kveite@online.no
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COMMENTS 12:
I would be interested to find out what enrichment products you are using and one other question.... Do the larvae die with their mouths wide open?
Howard W. Newman
Inve Aquaculture, Inc
Artemia Task Force Division
E-mail: BShrimp@aol.com
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COMMENTS 13:
We are using several different enrichment products both commercial and non-commercial, including DC DHA Selco. We would like to try out the DC line (Disifecting continuously) of INVE products but since the products only contain lipids and no protein, that should be the most important growth factor, we also use products with protein content.
I am not sure if the die mouth open or not... The big die offs caused by
this infections usually occurs 7 to 10 days after they stop feeding, so
cause of death is starving.
Olav Lyngstad
Norsk Kveite A.S.
Eikevaag
N-5314 Kjerrgarden
Norway
Tel/Fax: (+47) 56 14 52 05
E-mail: n-kveite@online.no
***************
COMMENTS 14:
I was heading towards an ammonia/nitrite problem but with this time lapse between the onset of non-feeding and death I am less inclined to believe it was either of these problems. Have you done a post mortem?
Howard W. Newman
Inve Aquaculture, Inc
Artemia Task Force Division
E-mail: BShrimp@aol.com
***************
COMMENTS 15:
Apologies for vague "Kick Start" reference in previous posting. It was
purely meant as an example of how even an extremely aggressive treatment of enriched Artemia with a surface disinfectant will not remove all of the associated bacteria. This is because a large number will be protected from the action of the biocide because they are inside the gut of the filter-feeding Artemia .
It certainly wasn't meant as a recommended and tested procedure! In this instance probably far better to follow the advice of Nick Brown and Peter Harvey and try a fresh water rinse. As they report, this should substantially reduce the levels of halophilic bacteria.
Kick Start is a commercially available biocide, routinely used in UK
hatcheries, containing, amongst other things, peracetic acid and hydrogen peroxide. As well as knocking all known germs flat in no time, it has the advantage that breakdown products are non-toxic so utensils can be rinsed in a solution and then left to air dry. I don't have product details of Kick Start to hand, hopefully one of the other list members can supply them.
In the particular experiment alluded to, Artemia, following enrichment in different commercial formulations, were immersed in a 1:250 solution for 5 mins (NOT 10 as earlier described- slip of the key), rinsed in sterile seawater, homogenised and plated onto TSA + SeaSalts and TCBS (for presumptive Vibrio spp.). As previously mentioned, levels of bacteria associated with the Artemia were substantially reduced BUT significant numbers still remained. Rather surprisingly, the Artemia themselves did not seem too bothered by the experience, I monitored them for up to 10 days post-treatment and they were still going strong. However, what immersion in a strong oxidising agent did to the carefully modulated enrichments I hate to think!
David Verner - Jeffreys
Division of Infection and Immunity
University of Glasgow
Glasgow G12 8QQ, UK
Tel: 0141 3306688
Fax: 0141 3304600
E-mail: djeffreys@mblab.gla.ac.uk
***************
COMMENTS 16 :
Kickstart is a 5% peracetic acid product manufactured by Solvay.
Peracetic acid is produced by a chemical process involving the mixing of acetic acid and hydrogen peroxide. Kick start has a level of about 22% hydrogen peroxide. It is an extremely strong oxidising agent. In trials for white spot in fresh water it killed rainbow trout in 10 minutes at 1.25 ppm. Hydrogen peroxide on its own has biocidal activity but possibly a safer oxidising agent to use would be chloramine - T although I have never used any of them to treat Artemia. I suspect that oxidising agents would be lethal.
Jim Mackie,
James A Mackie Group,
PO Box 14771, Alloa. Clacks, UK. FK10 2EW.
Tel: 44 + (0) 1259 215136
Fax: 44 + (0) 1259 211053
E-mail: mackieaquacultur@tory.org.uk
URL: http://www.scoot.co.uk/james_a_mackie/