27 Dec
2018
27 Dec
'18
8:04 p.m.
From: JEROME LAZARD <jerome.lazard(a)cirad.fr>
Sent: 27 December 2018 13:15
To: William Leschen <william.leschen(a)stir.ac.uk>
Subject: TR: BROOD STOCK STOCKING DENSITY
Dear Will,
Here is the translation. Very happy new year for you and your family, très amicalement,
Jérôme
En général en aquaculture lorsque l'on exprime le volume d'eau en m3 il s'agit
d'infrastructures telles que des bacs (en béton, en PVC, en plastique etc…) dont la
productivité (et la capacité de charge) dépend en priorité du débit d'eau
d'alimentation. Les densités de mise en charge seront très différentes selon que ces
infrastructures sont utilisées pour la production d'alevins ou pour le
grossissement.
En revanche, s'il s'agit d'étangs en terre, leur dimension est exprimée en m2
car la productivité naturelle sous l'action du soleil y est prépondérante et le débit
d'eau entrant dans l'étang est généralement très faible.
Dans le cas des bacs la densité de mise en charge est exprimée en nombre de poissons/m3 et
en nombre de poissons/m2 pour les étangs.
Cependant, pour la production d'alevins en bac, on exprime le nombre de géniteurs/m2
car l'essentiel du processus de reproduction se déroule sur le fond.
En résumé: pour les bacs les densités de mise en charge s'expriment en individus/m2
pour la reproduction et en individus/m3 pour le grossissement; pour les étangs les
densités s'expriment en individus/m2.
Amicalement, Jérôme Lazard
De : JEROME LAZARD [mailto:jerome.lazard@cirad.fr]
Envoyé : vendredi 21 décembre 2018 13:16
À : 'Pascal Azah'; 'Alexandra Pounds'
Cc : 'Sarnissa-french-aquaculture Mailing List';
'sarnissa-french-aquaculture-owner(a)lists.stir.ac.uk'.uk';
'sarnissa-african-aquaculture-request(a)lists.stir.ac.uk'.uk';
'sarnissa-african-aquaculture-bounces(a)lists.stir.ac.uk'
Objet : RE: BROOD STOCK STOCKING DENSITY
usually when one talks about m3 it concerns tanks (concrete, plastic …) and what matters
is the water flow going into your tank which will lead your carrying capacity. Of course
stocking rates will not be the same for fry production or for grow-out. On another hand
when we talk about earthen ponds, the stocking rate of fish is expressed in m2 because
usually the water flow into most of ponds is low if not insignificant.
Going back to the stocking rate of tanks (or small ponds), the number of fish is
restricted due to behavior of broodstok (aggressiveness) that does not allow more than a
few/m2. The area unit is m2 because reproduction process takes place on the bottom.
Conversely grow-out takes place in the whole water body of your tank and is then expressed
in m3.
If I am not clear, do not hesitate to come back. cheers, Jérôme Lazard
De : Sarnissa-african-aquaculture
[mailto:sarnissa-african-aquaculture-bounces@lists.stir.ac.uk] De la part de Pascal Azah
via Sarnissa-african-aquaculture
Envoyé : vendredi 21 décembre 2018 11:42
À : Alexandra Pounds
Cc : Sarnissa-french-aquaculture Mailing List; sarnissa-african-aquaculture Mailing List;
sarnissa-french-aquaculture-owner@lists.stir.ac.uk<mailto:sarnissa-french-aquaculture-owner@lists.stir.ac.uk>;
sarnissa-african-aquaculture-request@lists.stir.ac.uk<mailto:sarnissa-african-aquaculture-request@lists.stir.ac.uk>;
sarnissa-african-aquaculture-bounces@lists.stir.ac.uk<mailto:sarnissa-african-aquaculture-bounces@lists.stir.ac.uk>
Objet : Re: BROOD STOCK STOCKING DENSITY
Hi Bro Alex
Thanks so much for the contribution. I am grateful.
Kindly explain the following which bothers my mind.
In the stocking density for the tilapia grow out, we talk about cubic meter (m3) which
expresses volume, example 50 fishes per m3 but in the case of brood stocks we talking
about square meter (m2) which is an area example 4 fishes per m2. Kindly help me
understand why the difference please.
Pascal
On Thursday, December 20, 2018, 1:52:50 PM GMT, Alexandra Pounds
<alexandrapounds@gmail.com<mailto:alexandrapounds@gmail.com>> wrote:
Hi Pascal,
AgriTT recommends 3 fish per m2 (link:
http://knowledgeshare.sainonline.org/wp-content/uploads/2017/04/Tilapia-See…)
Similarly, these papers (Ridha & Cruz 2001; Abou-Zied 2012) found the 4 fish per m2
performed significantly better than 6, 8 or 12 fish per m2
(link: https://onlinelibrary.wiley.com/doi/abs/10.1046/j.1365-2109.1999.00311.x)
(link:
http://www.fayoum.edu.eg/Agriculture/AnimalProduction/pdf/Effectoffeedingra…)
Also similarly, Texas A&M AgriLife notes: "Stocking rates in spawning ponds vary
from 3,000 to 10,000 fish/ha at sex ratios of 1 female:1 male to 4 females:1 male."
(Link:
http://fisheries.tamu.edu/files/2013/09/Farm-Level-Issues-in-Aquaculture-Ce…)
I'd imagine that a low stocking density is required since the males are territorial
and make circular nests on the bottom that can be quite large... But that is a guess.
Perhaps other members could comment with their own experiences?
Best,
Alexandra
On Thu, Dec 20, 2018 at 9:58 AM Pascal Azah via Sarnissa-african-aquaculture
<sarnissa-african-aquaculture@lists.stir.ac.uk<mailto:sarnissa-african-aquaculture@lists.stir.ac.uk>>
wrote:
Hi Members
I kindly request advice on the appropriate stocking density for tilapia brood stock.
I am aware of 50 per Square meter for grow out but have not heard of that of brood
stocks.
Counting on members please
Thanks
Pascal
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Alexandra Pounds
MSc Sustainable Aquaculture, University of Stirling
BSc Earth Systems, Stanford University
(+1) 650.336.4554
(+44) 757.283.9224