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IMPORTANCE OF MONITORING AND GOOD BIOMETRIC PRACTICES IN AFRICAN AQUACULTURE

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Abstract

Aquaculture Researcher, Fish Nutrition. Morocco The success of an aquaculture project depends on several factors and decisions made by its owner, whose expertise is essential in this sector. These include the possibility of taking biometric measurements on fish, a process that provides information on the evolution of the production cycle and facilitates the choices made to improve performance, as well as recognizing the homogeneity or heterogeneity of batches of fish.
IMPORTANCE OF MONITORING AND GOOD BIOMETRIC
PRACTICES IN AFRICAN AQUACULTURE
By: Dr Mustapha ABA, Aquaculture Researcher, Fish Nutrition. Morocco
The success of an aquaculture project depends on several factors and
decisions made by its owner, whose expertise is essential in this sector. These
include the possibility of taking biometric measurements on fish, a process
that provides information on the evolution of the production cycle and
facilitates the choices made to improve performance, as well as recognizing
the homogeneity or heterogeneity of batches of fish.
1- Introduction
Biometrics is a recommended practice for monitoring aquaculture production,
and is considered a simple, fast and extremely effective procedure. The costs of
its implementation are also low, since the materials required are not as
expensive.
Nevertheless, many aquaculturists still have doubts as to whether it is really
necessary to carry out the procedure, as well as its benefits or how to carry it
out properly. In order to learn more about the practice, it is important not to
compromise the health of the animals, as inadequate management can lead to
losses due to fish mortality.
This article, presents some information on biometrics in fish, from defining the
practice and its importance, to the technique of carrying it out, with the hope
that for African fish farmers, this article will provide them with technical
assistance, as biometrics in Africa is unfortunately a practice that is only carried
out in scientific research and not in practice in most fish farmers.
2- Definition of biometrics in fish
The term biometrics, bio = life and metric = measured, is the science of
measuring living things, a scientific basis for using metric data to statistically
study the physical characteristics that indicate the development of fish in a
given production unit.
The aim of this practice is to identify problems in the development of fish,
closely related to feeding, i.e. the rate of feeding in relation to weight gain. In
this way it is possible to make modifications that improve the development of
the farm and, consequently, generate more positive economic results for the
fish farmers.
3- Importance of biometry in fish farming
It is clear that the performance of biometrics in fish is fundamental to reducing
the risks associated with the practice of fish farming. The procedure allows the
fish farmer to monitor the development of the fish, identifying if there is a
problem that may cause economic damage.
This practice also makes it easier for the farmer to optimise the growth of his
fish, ensuring that the quantity of feed is always in accordance with the
conditions observed in each of the production ponds and within the limits of the
feed manufacturer’s indication. As a result, aquatic animals will have good
characteristics and qualities in the consumer market, which will help to increase
their commercial value.
4- Frequency of biometry in fish
According to several recommendations, biometrics should be taken every two
weeks or at least once a month. Ideally, biometrics should be taken every two
weeks; it is advisable to do them on the same day of the week, which creates a
healthy routine. The best time is in the morning, before the first ration,
preferably a few hours before, which allows the handled fish to rest and feed
after the biometry.
5- Scaling
Maximum care in handling is essential, as any injury to the animals can
contribute to the development of disease and may result in the death of the
fish. To start the biometric process, you must first catch the fish. The use of nets
is recommended for this purpose.
The definition of the sample and its reliability is one of the most complex
statistical processes, the main reason is that the specific coefficient of variation
is unknown, because each crop has particular characteristics that make it
impossible to standardize, however, there is a statistical device that defines a
sample with adequate reliability, that is to say, apply the square root to the fish
population. Example for a number of fish of 1314 would require a sample of 36
fish.
6- Precautions to be taken
It is very important to refine a quick and efficient procedure that will allow fish
sampling to be carried out with minimum impact on the total population. The
sample should be treated carefully, using rubber gloves so as not to affect the
mucous membrane of the fish skin and to keep the fish in clean and oxygenated
water, in general it is not necessary to use anaesthetics unless the sample is
very large.
7- Materials needed for the procedure
The materials needed to perform biometric measurements can be available to
all aquaculturists because of their non-exorbitant cost and that the
aquaculturist can manufacture himself on his farm, among these materials are :
Ichtymeter: preferably portable so that management can be carried out
next to the production unit in a simplified and quick way, because these
animals do not survive out of the water;
Weighing scale: for fish handling and biometrics, a precision scale is
required.
Annotation material: notebook, notepad, where the data obtained are
written down for future evaluation.
Net of Fish, for the capture of samples.
8- When to perform Biometry
In order to reduce the stress on the animals, generated by all the handling,
moving and catching of fish to carry out this procedure, it is indicated that it is
carried out in the first hours of the day.
At present, the temperature and relative humidity of the air, as well as the
incidence of the sun’s rays, are at less aggressive levels for these organisms of
aquatic life. In addition, it is important to stress the importance of carrying out
this procedure before the first feeding session of the day.
9- Calculations
Now that the weighing has been completed, it is time to evaluate the data
collected. The first step is to calculate the sample weight using :to calculate the
average individual weight of the fish in the sample. Use it for this :
average individual weight = sample weight ÷ number of fish sampled
With this value, the total biomass in the sampled tank can be determined using
the following formula :
Total biomass = average individual weight x number of live fish stored in the
pond or tank.
Note: Remember to discard dead fish observed throughout the production cycle
in each sampled pond to arrive at more accurate biomass values.
10 Analyses
With the values obtained and calculated, it is sufficient to check the reference
tables and make the necessary adjustments in the fish feed, taking into account
the parameters indicative of the water quality of the ponds or basins and the
water temperature. In addition, it is possible to understand the course of the
activity, such as weight gain from one period to the next.
11- Conclusion
Biometrics involves weighing samples of fish or fry, which are being reared, in
order to calculate the total biomass. From this sampling, the producer can
calculate and determine the amount of feed to be fed to the fish on a daily basis
based on tables provided by the feed producers. In addition to monitoring
health status to avoid production losses due to disease or poor feeding. It also
allows the producer to have a forecast of the time needed to fatten up to the
ideal commercial weight, and the amount of feed needed during aquaculture
production.
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