Learn how to sample

1. Presentation on Sampling and
analysis of Fish, Water and Ice
By
Damale Herbert
Fisheries Officer
Directorate of Fisheries Resources, MAAIF

2. Introduction
• What is sampling
• Sampling refers to the process of selecting a subset of a larger
population or group in order to gather information or data that
can be used to draw conclusions about the population as a
whole. In other words, sampling involves selecting a
representative portion of the population to study, which allows
for more efficient and cost-effective data collection than would
be possible by studying the entire population. The sample
should be selected in a way that minimizes bias and ensures
that it is representative of the larger population

3. Types of samples collected
1. Water
• Raw/untreated water e.g. directly from the source such as alake
• Process/Portable water e.g. municipal water
• Effluent
2. Ice
3. Fish (whole fish, fillets, H&G, etc,)
4. Swabs

4. Common methods of sampling
• Random sampling: Fish are selected randomly from a particular area
to ensure that the sample is representative of the fish population in
that area.
• Composite sampling: Water or fish is collected from multiple
locations and combined into a single sample to provide an overall
picture of the quality across a larger area.
• Stratified sampling: The fish population is divided into subgroups
based on characteristics such as size, species, or location, and fish
are selected from each subgroup in proportion to its size.
• Purposive sampling: Fish are selected based on a specific criteria,
such as size, species, or location, that is of interest to the
researcher.

5. Sampling plan
A sampling plan is a document that outlines the type and number of samples
to be collected and area of sampling. It also contains the frequency of
sampling in a specified period of time for a given parameter.
Frozen/chilled fillets – Microbiology
- TVB-N
- Pesticide residues
- Heavy metals
Water/Ice – Microbiology
- Physiochemical
- Heavy metals

6. Sampling Materials and Equipment
Sampling materials
• PPE (Overcoat, gloves, masks, safety goggles etc)
• Disinfectant
• Cotton wool
• Lighter
• Lighter/matchbox
• Sterile sampling bags
• Cool box
• Sample bottles
• Swabs
• Labels
• Sampling forms
Equipment
• Temperature probe
• Grab sampler
• Portable pH meter
• DO meter
• Colorimeter
• Scoop

7. Sampling procedure for process water
• Clean and dry the outside of the faucet. The faucet could be sterilized by flame or ethanol
• Let the water run from the fully opened faucet for at least one half of a minute prior to sampling
• Partially close the tap sufficiently to permit collecting the sample without splashing.
• Open the bottle carefully to ensure no contamination of cup or lid or the inside of the bottle.
• Fill the bottle carefully without splashing and be sure no water from the hands of the inspector or other
objects other than water sample enter the bottle. Do not rinse the bottle.
• Fill the Sample Submission Form and deliver it with the sample to the laboratory promptly.
• Transport the sample in an insulated container under chilled conditions.
Note: Sterile bottles shall be used and if the water supply is chlorinated, inactivation shall be done using 0.1ml
of 2% Sodium thiosulfate sufficient to provide 100mg/L in the sample.

8. Sampling procedure for Ice
• Aseptically collect the ice into a sterile bottle or bag followed by sealing.
• Fill the Sample Submission Form and deliver it with the sample to the laboratory promptly.
• Transport the sample in an insulated container under chilled conditions
• Submit sample to the designated laboratory

9. Sampling procedure for finished product
• Determine the quantity (no. of boxes) of finished product in the consignment.
• Determine the sample size using the standard sampling plan (take a piece from each box in the sample size).
Note: Sampling should be done in a manner that it should represent the whole consignment and that it should
not affect the quality and safety of the product.
• Disinfect the sampling equipment and take the readings of temperature using a temperature probe.
• Put the composite fish samples in a sterile Ziplock sampling bag and seal tightly.
• Fill the sample submission form to be delivered together with the sample to the laboratory
• Store in an insulated container under cold conditions
• Transport the sample to the laboratory for analysis.

10. Codex Alimentarius Sampling Plan
N number of containers per lot Sample size n C Maximal number of acceptable
defective units
Containers with < 1 kg
N = 4800 or less
4801 to 24000
24001 to 48000
48001 to 84000
84001 to 144000
144001 to 240000
>240000
n=6
13
21
29
48
84
126
c= 1
2
3
4
6
9
13
Containers with 1 to 4.5 kg
N = 2400 or less
2401.To 15000
15001 to 24000
24001 to 42000
42001 to 72000
72001 to 120000
>120000
N= 6
13
21
29
48
84
126
c= 1
2
3
4
6
9
13
3- containers > 4.5 kg
N = 600 or less
601 to 2000
2001 to 7200
7201.To 15000
15001 to 24000
24001 to 42000
>42000
n= 6
13
21
29
48
84
126
c=1
2
3
4
6
9
13