Nominal CatchesThe concept "NOMINAL CATCHES" refers to the landings converted to a live weight basis. In fact it is often referred to as the "Live weight equivalent of the landings" or shortened to the "Live weight". In national publications the same concept is also given the name "Landings on a round, fresh basis", "Landings on a round, whole basis" or "Landings on an ex-water basis".

Landed WeightThe concept "LANDED WEIGHT" refers to the mass (or weight) of a product at the time of landing, regardless of the state in which is landed. That is, the fish may be whole, or gutted or filleted. Consequently this unit is of limited use for further analysis except where it is known that the product is very homogenous in nature. Where more detailed analysis of the data is required the landed weight is generally converted to a more meaningful measure, the most frequently used being the "Nominal catch".

Product WeightThe concept "PRODUCT WEIGHT" suffers from similar disadvantages being simply the weight of a product at the time of weighing. Thus it does not describe the presentation of the product and, unless it is known that the product is homogenous in form, further analysis has to proceed with caution.

Although the NOMINAL CATCH is, at first sight, the preferred unit it does suffer from one disadvantage, namely, that it is seldom obtained as a direct measure. This is because it would usually have to be made on board a fishing vessel where the practical difficulties associated with the working conditions render it impossible. Thus it has to be derived and this is usually done by applying a conversion factor (see Section I) to the landed weight.

Care should be taken when referring to the NOMINAL CATCH (the live weight equivalent of the landings) as the CATCH, since in many situations the initial catch (the GROSS CATCH) has been reduced by a number of factors. These factors are best illustrated by reference to the following link: Annex B I

Note:
Many national statistical publications do not use the terms "catch" and "landings" with the precise meanings as described in this section. In such publications "catches" may in fact refer to the "landings" and be expressed on a landed weight basis. However, only where the primary production (used in the economic and not the biological sense) is landed whole it is correct to refer to such quantities as "catches".