It is established that the sampling procedure
affects the composition of the sample
(McDonald and Milligan, 1992). Thus, precise
knowledge of alteration sources is necessary
to choose an adequate sampling method for
a given study and to make a correct interpretation
of the results. Caudal transection (CT)
and caudal vein puncture (CVP) of stunned
fish are widely used in fisheries research. In
addition to modifications of blood chemistry
associated with a physiological stress response
due to chasing and handling (see review by
McDonald and Milligan, 1992), the trauma
associated with sampling itself leads to contamination
of the sample by intracellular fluid
(Ikeda et al., 1985; Ikeda and Ozaki, 1981).