Isotope-ratio mass spectrometry isotopic make up of the sample is obtained. For example, carbon isotope ratios are measured relative to the international standard for C. The C standard is produced from a fossil belemnite found in the Peedee Formation, which is a limestone formed in the Cretaceous period in South Carolina, U.S.A. The fossil is referred to as VPDB (Vienna Pee Dee Belemnite) and has C:C ratio of 0.0112372. Oxygen isotope ratios are measured relative the standard, V-SMOW (Vienna Standard Mean Ocean Water). It is critical that the sample be processed before entering the mass spectrometer so that only a single chemical species
Standard weight in fish common measures of condition used in fisheries assessment and management. Fulton’s condition factor, K, is another measure of an individual fish’s health that uses standard weight. Proposed by Fulton in 1904, it assumes that the standard weight of a fish is proportional to the cube of its length: formula_2 where "W" is the whole body wet weight in grams and "L" is the length in centimeters; the factor 100 is used to bring K close to a value of one. Standard weight in fish Standard weight in fish is the typical or expected weight at a given total length for