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This read me explains the different columns from the fishbiomass.csv data. Data includes fish information for the Parmentier et al (2025) article
"Small fish biomass in the North Sea is far greater than previously estimated"
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StationID: Sample station unique code
Species_reported: Species name in Latin
Size_value: Length value
Size_unit: Unit of Size value (mm, 1/2cm, or cm)
Fraction: Proportion of the haul that was sorted 
Comment: Additional remarks or notes
Count: Number of individuals for this record or row (specific fish and size). For sandeel, either the number of heads or tails (whichever is higher) is recorded as the count; the other is set to zero to avoid double counting
WW_g: Wet weight in grams
Weight_type: Indicates how the wet weight (WW_g) was recorded. Entry: The weight (WW_g) corresponds to a specific record—i.e., an individual size class of a fish species. Sample: The weight represents a combined total for multiple records (e.g., several size classes grouped together)
is_Partial_WW: Indicates whether the weighed fish was whole (0) or damaged/partial (1)
survey: Identifies the research cruise during which the sample was collected
length_pred: Estimated fish length (in cm), either calculated from measured weight or predicted from a length distribution when only count data was available.
WW_g_pred_individual: Estimated wet weight (in grams) for one individual, derived from the species-specific length–weight relationship when actual weight measurements were not available.
WW_g_pred_group: Estimated total wet weight (in grams) for multiple individuals within the same record, calculated by multiplying the predicted individual wet weight (WW_g_pred_individual) by the count of individuals
ratio_withinSample: Ratio of the predicted group weight (WW_g_pred_group) distributed across multiple size classes
expected_WW_g: Estimated individual wet weight, calculated by dividing the measured sample weight (WW_g) using the ratio_withinSample
length_cm: Lenght of fish in cm.
unique_code: A unique code per record based on StationID, Species_reported, Length_cm