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Hatching brine shrimp
Subject: Hatching brine shrimp
After hatching brine shrimp for about 30 years and using it at the rate of
about 1/8th to 1/4th of a cup of cysts hatched a day for the last 15+ years
I would have to say that most of the information passed on about hatching
shrimp falls under the category of old wives tales. There is only one
requirement, the eggs/cysts need to be kept suspended or the hatch rate is
abysmal. I will argue that light other than providing some sort of heat
source is unnecessary. My understanding is newly hatched shrimp do not
require food until they molt once and that occurs 12 hours or more after
hatching at about 70oF. Once the shrimp hatch, agitation in the hatchery is
important for now supplying oxygen to the newly hatched shrimp.
In chemistry, the rate of a chemical reaction effectively doubles for each
10o (Centigrade) you raise the temperature (or 18oF). Heating the hatching
conditions reduces the time to hatch the shrimp but also shortens the window
in which they remain alive without requiring food.
I hatch my shrimp in one gallon pickle jars aerated simply with an open
airline that extends to the bottom of the jar. Enough air should be flowing
to create a "rolling boil" much as you see when water boils. This is enough
air to keep cysts suspended for hatching. At this rate about half way into
hatching you will observe eggs/cysts at the top but not a lot of dispersion
of cysts up the sides of the jar. Once hatching begins, the lighter egg
casings will start to form an encrustation a bit farther up the sides.
I hatch the cysts on the floor of my basement (my fish room) and the
temperature there can be in the low 60's(oF) much of the year. I hatch
maximum in each of two jars (currently although sometimes one and on a few
occasions as many as three) about 1/8th of a cup of cysts. Normally
hatching takes about 3 days (68-76 hours) at those temperatures. Under
warmer conditions (when the furnace is operating) this may shorten to 60 or
48 hours. Hatches are usually complete and there is the 12 hour window
mentioned earlier so most shrimp are alive at harvest. I rotate 8 jars
leaving two prepared with salt water after harvesting to allow the salt to
fully dissolve (although not always critical because you can add eggs and
salt at the same time and the salt will be dissolved by the time the shrimp
start to hatch) and the hatch water to reach room temperature (i.e.,
hatching conditions).
I usually maintain each jar in a plastic bucket so salt spray and "bubble
over" is contained but recently I started to "tip" each bucket a bit so the
jars really sit at an angle as well and I think it improves
circulation/agitation of the cysts. I don't reuse hatching solution and use
a commercial feed salt (crystalline) that costs about $10 for 80 pounds and
lasts me about 9-12 months (most farm supply stores carry it). I also clean
each jar out with a coffee urn brush prior to reuse/setup. I also wipe off
each airline to remove any slime from the last hatch, if not it impacts on
the hatch rate for that next batch. I also think by using the jug/jar the
flow dynamics of the curved top will cause the agitated water to rinse back
into suspension much of the cysts which are rinse onto the sides of the
vessel in the first place. This is a fallacy of the soda pop bottle and the
hatching cones.
One thing to look into is the processing of the hatched shrimp, more shrimp
will be lost here than on the sides of the hatching container. Shrimp are
separated from unhatched cysts and egg casings gravimetrically. I rinse my
harvested shrimp with about half as much fresh water as I use in the
hatching vessel, i.e., about 2 quarts per jug, in order to reduce the
carry-over of sodium into my tank and fry trays. Once the harvest is rinsed
I again suspend it in about one pint of fresh water and add it to a
separatory funnel and allow the phases to separate drawing off the newly
hatched shrimp on the bottom usually without much of the egg casings (which
are at the top). If you are having problems caused by a bad grade of cysts
you can resuspend the shrimp/cyst layer in increasingly salty water until
you get a phase separation of shrimp and cysts, unfortunately this takes
awhile to get it right and you may kill off the shrimp by taking too long in
processing! You can duplicate a glass separatory funnel cheaply by using a
water bottle with one of those flow control tops on many brands of bottled
water. (BTW, those tops are standard hose thread and can function as cheap
on/off valves in a flow through system).
As I pointed out before, controlling heat is used only to make hatching and
harvesting routine for you. Since I have 3 days of shrimp in the process of
hatching at any one time and deal in multiples of 4 to accommodate this,
although it takes up some space, this is on floor space where I would not
place tanks in the first place and does not consume unnecessary lighting or
heating costs. In addition, I purchased a case of "Russian" cysts some time
ago which many people at the time said produced lousy hatches. I found they
worked nicely for me at 4 days instead of 3. My only problem was the cysts
were not cleaned sufficiently during processing and left a lot of "junk"
(i.e., metal sulfides) in the bottom of the jar.
Dave Koran
BTW, this year's cyst harvest on the Great Salt Lake was at 12.3 million
pounds when last reported as of Friday, November 2nd. The Utah DWR is
suspending the harvest today (the 8th) at 5:17 PM until next Thursday at
noon. Average daily harvest are in the 3/4 to 1 million pounds per day.
Last year's harvest was just under 20 million pounds which turned into 7
million pounds of processed cysts. A strategy was developed last year when
it appeared that there was going to be an especially wet winter which
normally translates into a very bad harvest season and the cyst suppliers
"banked" half of their stock for this year. A very dry summer has
essentially gotten conditions to near what they were last year.
Date: Wed, 7 Nov 2001 21:11:11 EST
From: Misajegar at aol_com
Subject: Hatching brine shrimp
I've got an inverted liter-bottle brine shrimp hatching system (air bubbles
up thru the cap)....
How do you keep the eggs from being pushed up the side and left out of the
water from the bubbles????? This would seem to be an awful waste of eggs.
If I turn the air down so that the eggs won't be splashed onto the sides,
there really isn't enough movement to keep it properly stirred (right/wrong
on amount of air????).
- ---------------
Date: Wed, 07 Nov 2001 19:40:53 -0800
From: Wright Huntley <jwwiii at pacbell_net>
Subject: Re: Hatching brine shrimp
Misajegar at aol_com wrote:
>
> I've got an inverted liter-bottle brine shrimp hatching system (air
bubbles
> up thru the cap)....
>
> How do you keep the eggs from being pushed up the side and left out of the
> water from the bubbles????? This would seem to be an awful waste of eggs.
Are they eggs, or shells? They look alike but are very different. My bottles
(1.5 or 2L) have a lot of dark things up there, but mostly only on the
second
day. Shells float, but well-wetted eggs always sink.
> If I turn the air down so that the eggs won't be splashed onto the sides,
> there really isn't enough movement to keep it properly stirred
(right/wrong
> on amount of air????).
First, never add eggs to salty or even hard tap water. [Flame shield going
up!]
Properly hydrating the eggs in soft fresh (RO or DI best) water for a few
minutes, before adding any salt, goes a long way to keep them sunken. The
total number lost on the sides is then a very tiny percentage of the total.
Swirl them back into the solution, as you pass by later, if that tiny loss
bothers you. Once they hatch, though, almost *all* of them should be up
there
near or above the water surface.
You do need vigorous agitation (motion plus oxygen), strong light (2000 fc),
and heat (80-85F) to get a really good hatch. Lack of those will lose far
more
nauplii than the few on the sides of the container, IMHO.
Wright
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