this section. The guidance provided below focuses primarily on field 

 surveys or monitoring programs involving the collection of samples 

 directly from aquatic environments, or from harvesters when the 

 specific geographic origin of samples is known. Such guidance is 

 directly relevant to analysis of recreational fisheries. The present 

 document does not specifically address approaches to marketplace 

 sampling of commercial fisheries products, although some of the con- 

 cepts discussed below apply to marketplace surveys. Sampling designs 

 for collection of fisheries products from the marketplace are available 

 in FDA Compliance Program Guidance Manuals (e.g., U.S. FDA 

 1986). Sampling of commercial fisheries directly at the source is 

 preferred over marketplace sampling because the former generally 

 allows documentation of the samphng location. 



If the exposure assessment is designed to include contaminant intake 

 from consumption of commercial fish and shellfish, samples may be 

 obtained in two ways. First, samples of target species can be obtained 

 directly from commercial fishermen. In this case, a strict quality 

 assurance/quality control (QA/QC) program should be implemented 

 to ensure proper handling, storage, and documentation of samples. 

 Documentation should include sampling location, species name, size 

 (length, carapace width, or shell height/width), weight, sex, reproduc- 

 tive condition, time and date of sampling, and preservation technique. 

 In most cases, a technician or observer should be on board the fishing 

 vessel to maintain proper sample handling and documentation. Alter- 

 natively, samples may be collected by monitoring program personnel 

 using vessels other than commercial fishing boats. In this case, samples 

 should be collected in a way that simulates commercial fishing prac- 

 tices as closely as possible (e.g., same species, size classes, season, 

 fishing area, sampling method, and water depth). Regardless of the 

 general approach to sampling, the organisms collected should be 

 placed directly in temporary storage on board the sampling vessel. 

 Upon return to shore, resection of samples should be accomplished as 

 quickly as possible using an adequate clean-room. If an extended 

 sampling cruise necessitates resectioning on board, an adequate clean- 

 space should be set aside to ensure that samples are not contaminated. 



Analysis of chemical residues in tissue to support an exposure assess- 

 ment is one kind of bioaccumulation study. Bioaccumulation is 

 defined here as the uptake and retention of a contaminant (e.g., a 

 potentially toxic substance) by an organism. The term bioconcentra- 

 tion refers to any case of bioaccumulation wherein the concentration 

 of contaminant in tissue exceeds its concentration in the surrounding 

 medium (i.e., water or sediment). The phrase "bioaccumulation sur- 

 vey" will be used below to refer to measurement of chemical residues 

 in tissue samples from fish and shellfish collected in the field. 



The elements of a study design for analysis of chemical residues in 

 tissue include: 



• Objectives 



• Target species and size (age) class 



• Sampling station locations 



• Target contaminants 



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