Fish Fatmeter FAQ’s

Battery not holding charge

Question

We have been using the fatmeter for about 2 months on Albacore tuna. It seems all works fine, however the battery does not seem to keep the charge. Procedure we are using is to charge the fatmeter every night all night long. In the morning we check the calibration with the pad and during the day we use the fatmeter about 10 times. Each operation will last for a maximum of 5 minutes and between operations we turn it of. So in total the fatmeter will be used for about 1h to 1.5h at the maximum during the day, and yet around 5-6 pm the fatmeter indicates battery low. We rarely had that before while we were using it much more than 1 hour a day. We are planning to go on another trip with intensive use of the fatmeter and I am afraid we will be limited by this problem.

Could it be that the battery is dead already? Was it checked in January when we sent the fatmeter for revision, any solution? Is there any thing I could check?

Answer

It sounds as if the charger is NOT charging correctly (you are getting perhaps 1 hour before batteries are discharged, signifying only a partial charging of the batteries). I suspect that the cable at the 7-way plug has become twisted, and has caused a cable break inside 7-way Plug, and providing an intermittent charging of the batteries.

If you have an engineer available, ask him to check the 7-way Plug, and DC output voltage of the charger, when plugged into mains supply. He will need a Multimeter to carry out this check. Proceed as follows…

  1. Engineer should dis-assemble 7-way plug, and check if any of the TWO cable connections are broken off, inside. Any broken cable should be re-soldered, and 7-way plug re-assembled. Connections are… Pin 1 – Centre Pin = Live (+ve)..white, insulated cable. Pin 3 = Ground (-ve)… Un-insulated wire. If this is OK, then proceed to step 2…
  2. In the Charger’s connecting lead (with 7-way socket for plugging into Fatmeter)… Remove the FOUR screws from the small black box, and remove plastic lid.
  3. Engineer should then connect charger to Mains Power Socket (110V or 230V), and switch ON.
  4. Engineer should check to make sure that the RED LED is illuminated
  5. Engineer should measure the DC voltage across the two cables entering the black box… this voltage should be ~ 12 volts, DC (If no voltage at this point, this signifies that charger has failed, and we will require to send you a replacement).
  6. If voltage at 4 above is OK, engineer should check voltage across TWO cables exiting the black box… this should be 12 volts, DC ( If no Voltage exiting the black box towards the 7-way plug, then the fuse on the PCB has failed (we will need to send you a replacement Charger Unit).
  7. If correct voltage leaving the black box, then refit lid, and screws.

I do think that the most probable cause is twisted cable causing a fault at 7-way plug, on the charger unit.

Can it be used on LIVE Fish?

Question

Can it be used on LIVE Fish?

Answer

YES… because it is NON-INVASIVE and harmless, it can be used to monitor individual fish and how they respond to various diets.

Can I use the Fish Fatmeter on Skipjack 3 Kg and Yellowfin 10Kg up?

Question

Can I use the Fish Fatmeter on Yellowfin 10Kg up?

Answer

Yes… you can use the Distell Fatmeter for large Yellowfin tuna. We have specific calibrations available for each.

Can samples be used after testing?

Question

Can samples be used after testing?

Answer

YES… because the Distell Fatmeter is NON-DESTRUCTIVE, you can measure the same sample many times if necessary without affecting the quality of the fish.

Can the MEASUREMENT DATA be electronically stored for later use?

Question

Can the MEASUREMENT DATA be electronically stored for later use?

Answer

YES… The Distell Fatmeter has a memory facility which will store up to 1,000 sets of measurements. These reading can be downloaded into your computer at any time, using our Data Management Software. This Software is supplied as standard, when you purchase a Fatmeter.

Can we use the Fatmeter to measure processed Fish?

Question

Can we use the Fatmeter to measure processed Fish, even although the Fatmeter is not specifically calibrated for that product?

Answer

Yes, you can… let us explain… there are TWO categories of fish calibrations…

Calibrations for… Fish in the natural state…

The natural fish species calibrations are universal, and do not change significantly around the world. The one set of calibrations per species is sufficient.

Calibrations for… Processed Fish…

Artificially changed from the natural state, eg. Mateus Herring, Smoked Salmon, Salted Fish, Cooked Fish, etc.

The processed fish are different. Everyone has their own individual recipes, with varying amount of salts, spices, drying, smoking, or cooking processes. Therefore it is not possible to produce a universal calibration for each type of processed fish product. All we can do is create a Graph / Chart by taking an average of manufacturers samples, and combining the data. The accuracy achieved using the Fatmeter will vary between individual companies, depending on the quality control aspects of the process, and the quantity of food additives, smoking, brining, drying or cooking time.Distell can, of course, carry out a specific product calibration for a specific recipe, and thus monitor accurately the fat content variances encountered. However, when you consider that any one processor may have up to 300 different recipes, then it becomes uneconomic to carry out individual recipe calibrations… especially when each special calibration costs upwards of… £ 750.

The answer is simply to use a Graph / Chart… for the process. The operator can then log all of the results achieved using the Fatmeter on that particular fish product for perhaps the first 1-2 weeks, then carry out a series of laboratory analysis on the samples. This will allow the creation of a graphed “Table-of-Error”, such as the charts shown below. This will allow the company / operator to monitor the specification of the product, by allowing for this “error factor”.

Of course, it is necessary to compile a reasonable number of data samples, preferably reflecting the extremes normally encountered for that product in the process… from the very low fat content, to the very high fat content levels. This will ensure a good spread, and allow a clear picture of trends.

Thereafter, the Fatmeter can be used to accurately monitor the day-to-day quality and uniformity of that product, and allow rapid reaction, where product variances are encountered. This procedure can be adopted for most of the companies processed products.

The clear message is…

  • The Fatmeter does not necessarily have to contain a dedicated calibration for each and every processed product. Simply build up a library of ” Error Tables” for each product, and apply the error factor accordingly.
  • The Fatmeter is a quality monitoring tool, giving the operator the ability to check one days’ production against the next day. If the results are the same… day-to-day, then the specification is correct… if there is a variance from one day to the next, then this will be clearly highlighted and allow for investigation at an early stage.
  • Where there is a requirement for a dedicated, truly accurate calibration for a processed product, Distell can prepare an accurate calibration for that product.
Do normal laboratory tests still need to be carried out?

Question

Do normal laboratory tests still need to be carried out?

Answer

YES… BUT NOT SO MANY, because the Distell Fish Fatmeter is designed to allow many measurements to be taken to routinely screen the product. Occasional laboratory tests should be used can be used to confirm the Fatmeter measurements.

Does G-BREAM-1 corresponds to fat content of both sides trimmed fillet without skin?

Question

Does the G-BREAM-1 program option corresponds to fat content percentage of both sides trimmed fillets without the skin? If yes, I presume that any lipid content in the skin is substractedfrom the rest of the fillet content?

Answer

You are right… the *G.BREAM-1 Calibration* represents the fat content of.. *TWO x Trimmed fillets of the fish* /(ONE Trimmed Filletfrom each side of the fish)/. Skin should be removed before sending to the Laboratory for analysis /(Fat content of skin NOT included).

Does temperature affect the performance or results achieved using the Fatmeter?

Question

Does temperature affect the performance or results achieved using the Fatmeter?

Answer

Provided that the Fish or Fish Fillets being measured are not frozen, and no ice crystals present in the sample, temperature should have no significant effect. Where the Fish or Fish Fillets are frozen, or contain ice crystals, the Fatmeter will tend to over-read the Fat Content level… this is due to the Microwave system being unable to measure the water in the frozen state, thus interpreting a lower quantity of water in the fish… than is actually the case.

  • We have found that Fish and Fish Fillets down to –2°C normally do not contain ice crystals… and can be measured as normal.
  • We have also found that Fish or Fish Fillets, stored at or above 10°C, can suffer moisture loss, and create a variance from the Fatmeters’ Natural Fish Calibration.

For consistent, wholly accurate results, the operator should ensure that the Fish or Fish Fillets are measured at the same ambient temperature on a daily basis… within a temperature range of 0 – 10°C.

How accurate is the Fatmeter?

Question

How accurate is the Fatmeter?

Answer

For individual salmon, an accuracy level of +/- 1% can be achieved. For Herring the accuracy for a batch of EIGHT fish can be similar.

How can we resolve different results between the Fish Fatmeter and laboratory methods?

Question

We use the fish fatmeter to determine the fat content of sardine pilchards but we always have different results between the fish fatmeter (in example 6.85%) and the laboratory methods ( 3.85%) so we followed the instruction manual in order to verify the calibration with the low range pad (sardine 2 —- 8%) after 8 readings we found 10.75 %. So what we can do to resolve the problem.

Answer

It seems that your Fatmeter is “Out of Calibration” specifications. If the Fatmeter is reading high on Check Pad, then it will read high on Fish (as you have indicated in your Fat results). So that we can assess the options available, please supply answers to the following Questions…

  1. The name of your company
  2. Where are you based
  3. Contact telephone number, so that we can telephone you to discuss
  4. The Serial Number of the Fatmeter (so that we can check which model you have, and the calibrations programmed in Fatmeter).
  5. The Check Pad Readings on… Range 1 (reported as..8.0%), and Range 2 (Not reported).

There are TWO Options available…

  1. Best Option… Return the Fatmeter to.. Distell, in Scotland, UK for… Service & Re-Calibration.
  2. Depending on the model of Fatmeter… we may be able to supply a Re-Calibration by E-mail, with instructions on how to do this (latest models only).

Please supply information requested then we can decide on actions necessary.

How does the Fish Fatmeter work?

Question

I am a wildlife technician working on a research project on using the bioelectrical impedance to predicted fat mass in fish. We are know searching for availables methods to calculate fat mass in our samples. I wanted to understand how your Distell Fish Fatmeter works, what does it calculate to give the fat mass of a fish? Is it precise or really approximate, because we need really precise data?

Answer

Firstly… Principles of the Fatmeter…

The Fatmeter utilises low power microwave technology. The sensor transmits a microwave signal through the skin of the fish into the flesh. The microwave signal is attenuated by the amount of water present in the sample. Depth of penetration of the microwave signal is dependent upon the Water Content. In a healthy living organism there is this natural relationship between the amount of… Water, Fat & Total Body Solids. The main two variables are Fat and Water, with an inverse relationship between the two, with just a small change in the body solids (Protein, Minerals, Carbohydrate, fibre, etc). Using this relationship, we can create calibration algorithms to calculate the Fat Content of the sample. You can view the Science Publication on both Fish & Meat Fatmeters on our Website, under Product Information. Also on Website is details of AQIS Accreditation.

Secondly… Accuracy of Fatmeters….

My first reaction was that… as you are using bioelectrical impedance equipment to predict the fat mass in fish, then you should be going back to Chemical Laboratory Method for your comparative measurement. However, I realise that this can work out to be very expensive, especially if you intend to measure a large number of samples.

You can certainly use the Fish Fatmeter for your comparative measurement. Our Fatmeters are used around the world to measure Fat Content of Meat & Fish products. However, the main use of the Fish Fatmeter is to provide a rapid, non-destructive representative assessment of the fat content of … Whole Fish carcass, Trimmed Fish Fillets, Selected Sections, or directly on Fish Flesh. Our Meat Fatmeters are AQIS accredited to Chemical Lean (CL ) Standard. Overall… Distell’s Fish Fatmeter level of accuracy can be fairly stated, as that shown in the table below.

Accuracy of results

The accuracy of the FATMETER depends upon the fat/oil content of the sample being measured and ranges from an uncertainty in the fat content of (+/-) 1% (95% confidence interval) at low levels to (+/-) 4% at very high levels (greater than 45%). Therefore it is advisable that the operator follows the measurement methodology rigorously, and always takes readings as described in wall charts supplied.

Accuracy Guide

Fat/Oil Reading Accuracy
2 to 15% from.. ± 0.5%, rising to.. ± 1.0% ( 13 -15% at 14%)
16 to 30% from.. ± 1.0%, rising to.. ± 2.0% (28-32% at 30%)
31% and above from.. > ± 2%, rising to.. ± 4.0% (46-54% at 50%)

The results gained will allow the operator to take swift decisions regarding feeding or processing of the fish species being measured.

Other methods currently in use for determining the lipid content of fish samples are destructive and slow, eg. In fish, a section or fillet of the fish is taken and analysed for fat/oil content by weighing, and using solvents to extract the fat, or, by driving off the water content by heating. These methods, unlike the DISTELL FATMETER, obviously cannot be used on LIVE fish.

If you do not wish to use direct chemical analysis of samples as your comparsion for every sample, then my recommendation would be to trial / evaluate the Fish Fatmeter by rental for a period of … ONE Month. This would allow you test Fatmeter performance, and also carry out some comparative laboratory analysis. The advantage of the Fish Fatmeter being that you can create a custom calibration setting for your specific product, based upon your own measurement data, and then program the Fatmeter accordingly. If you have many samples to measure then the Fatmeter would be very cost effective.

How fast is the Measurement?

Question

How fast is the Measurement?

Answer

Approximately TWO minutes to take EIGHT MEASUREMENTS from a large Salmon. Much faster than any other methods for which sample preparation and measurement can be anything from 15 minutes to several hours.

I'm Interested in specs of your fat meter to use on pacific sardines

Question

I’m Interested in specs of your fat meter to use on pacific sardines

Answer

There are TWO Models.. FM 692 & FM 992…

Model FFM 692… Standard commercial model, with larger sensor.. most suitable for larger fish species, such as..Salmon, Tuna, Mackerel, Sea Bream, Sea Bass, etc. Can measure fish samples with a minimum body length of 10cm (excluding head and tail).

Model FFM 992… Smaller meter, with smaller sensor head.. most suitable for smaller fish species, such as… Sardine, Sprat, pilchards, etc. Can measure fish samples with a minimum body length of 5 cm (excluding head and tail).

For… Pacific Sardines we recommend the smaller sensor model … FFM 992.

Each meter can be programmed with fish calibrations of your choice, from our standard list attached. FOUR calibrations are included in the standard cost price. Also included is a Research setting + 5 Calibration slots for uploading your own custom calibration data. Additional standard calibrations are available.

If I send you my old fish fat meter, I can receive a new one with a discount?

Question

If I send you my old fish fat meter, I can receive a new one with a discount?

Answer

Yes.. we can offer you part exchange for your Old Fatmeter Kit, as a deduction from the purchase price of a NEW Fatmeter Kit.

Is it really portable?

Question

Is it really portable?

Answer

YES… unlike other methods, it is a HAND-HELD instrument powered by rechargeable batteries. The Fatmeter will operate for up to eight hours continuously.

Is it Waterproof?

Question

Is it Waterproof?

Answer

YES… to IP65 standards. This allows the Fatmeter to be used in very wet environments such as fish farms.

Is one of the Salmon salar calibations on whole gutted salmon?

Question

Is one of the Salmon salar calibations on whole gutted salmon, or is it also with belly contents ? I have to use it on whole gutted fish, and not on whole live fish.

Answer

No… We do not have a calibration setting for… Whole, Gutted Salmon. The Salmon calibration settings that we have, are as follows…

  • Salmon-1 (Measurements with Fatmeter represent the TWO Trimmed fillets, without skin)
  • Salmon-2 (Measurements with Fatmeter represent the MOWI Section of the salmon, without skin)
  • Salmon-3 (Measurements with Fatmeter represent the NQC Section of the salmon, without skin)
  • Salmon-4 (Measurements with Fatmeter represent the DORSAL Section of the salmon, without skin)

You will still have to create Error Chart, as described in previous e-mail, if you wish accurate measurements of the fat content of… Whole, Gutted Salmon or Trout.
Distell can prepare a specific calibration for… Whole, Gutted Salmon, or… Trout

Is the instrument applicable to fish with and without skin and frozen?

Question

Is the instrument applicable to fish with and without skin and frozen ?

Answer

The Fatmeter can be used to measure directly on the skin of the fish, or directly on the flesh of the fish (e.g. bone side). There are different calibration settings available for each method. The meter cannot measure fish / meat whilst in the frozen state… the fish/meat must first be defrosted before taking measurements.

Should the G.Bream-1 calibration provide similar results to the equivalent lab analysis?

Question

Should the G.Bream-1 calibration method provide us with similar results to the equivalent chemical lab analysis where a both-sides fillet without the skin is processed?

Answer

Yes… That is correct, so long as the Fatmeter measurements are taken, as recommended in the User Manual / Measurements Charts provided.

Some advice on using the Fish Fatmeter where you do not have a specific fish calibration available..

Question

Some advice on using the Fish Fatmeter where you do not have a specific fish calibration available…

Answer

The Fatmeter does not necessarily require to have a dedicated product specific calibration. It is easy to create your own “ERROR TABLE” without going to the expense of a dedicated calibration.

The Fatmeter is portable, and its advantage lies in its’ ability to monitor large numbers of samples rapidly and non-destructively. Thus checking Specification, Sample homogeneity, Product uniformity… day-to-day, hour-to-hour, if need be.

How to create the Error Table…

The enclosed example illustrates the results using the Fatmeter and then comparing with traditional laboratory method. We have prepared graphs of the data. The graphs allow you to see, at a glance… FOUR important factors… And allows the operator or quality control department the ability to monitor the following…

  • Product uniformity… hour-to-hour, day-to-day.
  • Sample variability from batch-to-batch, sample-to-sample.
  • Product is within specification requirement
  • Screen the production process at various points in the factory

The trend lines on the graphed results allow you to assess the value of the variance between your existing lab method and a chosen calibration setting on your Fatmeter. We have shown below TWO examples of different types of Fish, measured using the Fish Fatmeter on existing standard calibration settings. The samples were then sent to the laboratory for analysis, and the results of the Fatmeter were compared to the Fosslet Laboratory results.

By charting the results of the two methods ( it means that you can compare the Fatmeter results with any system currently in use within your facilities), the operator can readily prepare an “Error Table” and thus continue to use the Fatmeter for monitoring and measurement of any of their processed products… without going to the expense of a dedicated calibration.

What is the main use of the Distell Fish Fatmeter?

Question

What is the main use of the Distell Fish Fatmeter?

Answer

Its main use is to measure the Fat / Oil Content of FISH & FISH PRODUCTS eg. Salmon, Tuna, Trout, Herring Mackerel, Sardines, Smoked Salmon, and many other species of fish.

What precautions should I take when comparing Fish Fatmeter results with laboratory Analysis?

Question

What precautions should I take when comparing Fish Fatmeter results with laboratory Analysis?

Answer

This is a very important question, and great care should be taken to ensure rigorous attention to detail… . Where you know that the measurements made by the Fatmeter are going to be compared to some form of Laboratory Analysis, always ensure a rigorous preparation procedure. Otherwise you may get a different result from the laboratory, and this will create confusion and doubt.

The preparation instructions are clearly described in the Fatmeter Handbook, but for the avoidance of doubt we have given a brief description here, as follows…

Switch ON the Fatmeter and allow it to warm up and stabilise for 10 minutes. Then select the correct calibration, from the menu. You can confirm that it is the correct calibration by pressing the ‘RESET’ button on the Fatmeter… the selection will be displayed briefly on the LCD display.

You are now ready to take measurements… The Fatmeter will request a series of EIGHT readings. Please ensure that the readings are taken from around the sample… at recommended measurement sites, fully described in your handbook.

Place the sensor head fully in contact with the sample, being careful to exclude any air cavities. Press and hold the ‘READ’ button until the reading has stabilised, then release the button, whilst sensor is still firmly in contact with the sample.

Take all eight readings from various positions on the sample ( see chart supplied ). After the eight readings the Fatmeter will automatically display the Average Fat Content of the sample. The result should give accurate Fat Content, representing the Fat / Oil Content of the sample.

For the avoidance of doubt… Calibrations have been created to represent different portions of the fish. For instance… The following THREE Calibrations represent different portions of a Salmon…

Measurements taken on the ‘Mowi Section’ of the fish. After 8 readings the readout shows the average fat / oil content representing the ‘Mowi Section’ of this one fish (subject to ‘Mowi Standard trimming techniques’… please see appendix section for further details).

SALMON-1 Measurements taken along the length of the fish, BOTH sides. After 8 readings the readout shows the average fat / oil content representing Fat Content of… TWO x TRIMMED FILLETS of this one fish (subject to ‘Standard trimming techniques’ that is…excluding head, tail, fins, skin, belly cavity, and fat deposits at Dorsal and Anal Fins)
SALMON-2
SALMON-3 Measurements taken on the ‘NQC Section’ of the fish. After 8 readings the readout shows the average fat / oil content representing fat Content of the ‘NQC Section’ of this one fish (subject to ‘NQC Standard trimming techniques’… please see appendix for further details.

Having measured the sample with the Fatmeter, duly prepared samples should now be sent to the Laboratory for analysis, if you wish to confirm the performance of the Fatmeter. Remember, the laboratory only use between 9 – 25 gms of the fish sample for the analysis process, so you must ensure that the laboratory do in fact blend ALL of the fish sample… prior to taking their sample for analysis.
In addition, the laboratory must do triplicate analysis, taking a 2nd & 3rd sample from the blended sample. This ensures that we have a check on the uniformity of the blended product.

The Fatmeter can be compared with any recognised Lab Method. However, the Fatmeter has been calibrated against Foss-Let Chemical Method… an AOAC recognised Laboratory based Chemical Extraction Method. This will give the best comparative accuracy. There can be significant variances in Laboratory results depending on the method used, and we recommend that the method of comparison is taken into account. If you have followed carefully the instructions above, the Fatmeter results should compare favourably with laboratory results, and should be within the performance range quoted in Operators Manual.

Why are the fatmeters results different to the lab results?

Question

During our recent fat analysis for whole round sprats the machine was showing quite high values (sometimes – “out of range”) so we sent some samples to the lab for verification. There is big divergence between ours and lab results. Each sample send to the lab contained the same 8 fish checked by fatmeter, and I asked to blend all of the fish before sampling. Please can you tell us why the results are such different?

Answer

There are wild fluctuations in the fat content of the EIGHT samples that make up the average, in your samples… A, B, & C.

Sample A… 29.5, 30.3, 39.6, 23.8, 34.6, 12.3, 11.2, 37.7 Average = 27.3%

Sample B… 31.7, 19.5, 10.3, 31.9, 22.2, 24.0, 17.6, 30.2 Average = 23.4%

Sample C… 11.7. 9.0, 18.9 23.3, 21.5, 25.2, 29.0, 24.2 Average = 20.3%

I would make the following comments…

Measurement preparation…

In the above samples, I have marked the suspect values in RED. In my opinion these readings are the subject of Operator / Measurement Procedure faults, and some of the lesser values, in the sample are also suspect to a lesser degree.

It is important to group the fish into different grades, depending upon the Fat Content. This can be done quickly by screening the fish using the Fatmeter. Segregate the fish into different groups of fat content, as follows…

5- 10%

11 -15%

16-20%

20% +

The Fatmeter microwave energy penetrates into the fish to varying degrees, dependent upon the fat content / water content relationship, of the fish being measured… the greater the fat content (less water), the further the microwave energy penetrates through the fish (remember that the microwave energy is attenuated much more rapidly, when there is a high % of water present in the sample).

As a guide…

At ~ 7% Fat Content (~ 71% Water)… the microwave energy will only penetrate about 7-10mm through the skin and into the fish muscle.

At 15% Fat Content (~ 63% Water)… the microwave energy will only penetrate about 12 – 15mm through the skin and into the fish muscle.

At 25% Fat Content (~ 52% Water)… the microwave energy will penetrate about 20 mm through the skin and into the fish muscle.

Therefore it is IMPORTANT to ensure that when measuring high fat content Sprat, that the minimum thickness is 25mm. If the fish are thinner than this, then you must “double up” the fish (one fish on top of another, to achieve the minimum thickness), measuring on one side of each doubled-up fish sample.

It is very seldom that you get Sprat Fat Contents greater than…25%. The reason for the large measurement values is that you are measuring through the fish and onto the underlying surface (it is always best NOT TO MEASURE on a Metallic Surface, as this will give a higher degree of microwave signal reflection). This is causing erroneous readings, caused by reflections from the underlying surface.

You must always GROUP the Fish according to Fat Contents, and “double up” fish samples with a higher Fat Content depending upon the thickness of the fish samples.

If you follow this procedure, then you will avoid erroneous readings, caused by the microwave energy travelling completely through the fish, and reflecting from underlying surfaces.

Will measuring on, rather than above, the sideline (Lateral Line) affect our results?

Question

Turns out that some of our team have been using the fatmeter not quite as indicated in the manual (Salmon-1 program).

In other words, they have been measuring the fat more or less on the sideline of the fish, not above the sideline as indicated in the manual, and a bit askew from the designated areas. Will this affect our results significantly?

Answer

For a fish of similar size and weight… if you measure directly on the lateral line of the fish, then the measurements will be much more variable when measured on the lateral line, than if measured above the lateral line.

The reason… directly under the skin on the lateral line there is a strip of brown flesh, which tends to contain more fat and the amount of fat present in this area can vary significantly, from one fish to another, and can be caused by seasonal changes. If you measure above the lateral line then you are measuring directly into the fish flesh / muscle area, and this is much more repeatable / representative, and fat distribution in the flesh / muscle is less variable, from one fish to another, and seasonal changes are minimal.

What to do… Please select a number of samples of fish, and proceed as follows…

  1. The team should take readings ON the lateral line of the fish, as before, and note the measurement values
  2. The team should then take readings ABOVE the lateral line, as recommended in Measurement Charts supplied, and note the measurement values.
  3. Once you have collected the data, prepare a graph / chart of the measurements for each group, and extrapolate the data accordingly. You can then compare the data “scatter” from one group, with the other group.
  4. You can also compare the “mean” values of the TWO data sets, and use the chart to correct previous data sets.