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14 FRED P. MEYER AND ROGER L. HERMAN <br />the appropriate course of action to be pursued and <br />the types of samples to be taken. Specific details <br />regarding procedures to follow are given in later <br />chapters relating to each type of cause. <br />On-site Investigation <br />The investigation of a fish kill must be conducted <br />as a forensic investigation. Data collected must be <br />adequate to answer three basic questions: (1) What <br />is the manner of death-natural or otherwise? <br />(2) What is the mechanism of death-toxicosis, <br />asphyxia, or septicemia? and (3) What is the cause <br />of death-what started the lethal sequence of <br />events? <br />Collections of fish that are affected, but not yet <br />dead, are important to the investigation of any fish <br />kill, but they are not always made or may not always <br />be possible. The types of analyses to be done on the <br />fish depend on the observed and reported circum- <br />stances of the kill. Regardless of the suspected <br />cause, fish should be checked for the presence of in- <br />fectious or parasitic diseases, preferably at the site <br />(Chapter 6). If industrial or agricultural pollution is <br />suspected, chemical analyses are needed, and sam- <br />ples must be collected and preserved accordingly <br />(Chapters 4-6). <br />When an industrial or municipal discharge is sus- <br />pected, water samples should be collected above, at, <br />and below the point of discharge, as described in <br />Chapter 4. Then plant managers or other respon- <br />sible individuals should be contacted immediately to <br />inform them of the problem, to obtain information <br />about the possible contents of the discharge and <br />details of plant operation (particularly just before the <br /> <br />Water chemistry data should be collected as soon as possible after investigators arrive at the site of a fish kill.