Paul Dion asks for information regarding more objective , i.e. laboratory analysis, and less subjective organoleptic analysis. He should be more exact in the use of terms. Organoleptic' refers to the properties of a material capable of stimulating the senses.
Sensory tests can be objective or subjective.
An objective test should be used for grading for quality or for measuring a defined property. There are no existing laboratory tests that can in principle or in practice be used for grading the quality of fish at the dockside. I believe it is extremely unlikely that a non-sensory test will be developed that will outperform sensory assessment for grading of raw fish. Throughout the world, fish is bought at docksides or landing sites on the basis of sensory evaluation, and I am not aware of any marketing system that uses non-sensory methods. At its simplest, the grading is just buy or not buy, or to be more exact, buy or not buy at the particular price on offer.