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Analyze juvenile fish proportions in catches using length-weight relationships and catch data.
Calculate juvenile percentages from length frequency data:
# Calculate juvenile percentages
juvenile_results <- summarize_juveniles_by_group(
data = your_length_data,
group_cols = c("date", "fishing_zone"),
length_cols = c("8", "9", "10", "11", "12", "13"),
juvenile_limit = 12, # Size threshold in cm
a = 0.0012, # Length-weight coefficient
b = 3.1242 # Length-weight exponent
)
Use species-specific parameters for weight calculations:
# Calculate fish weights from lengths
weights <- calculate_fish_weight(
length = c(8, 10, 12, 14),
a = 0.0048, # Coefficient for anchoveta
b = 3.067 # Exponent for anchoveta
)
# Apply catch weighting to length frequencies
weighted_data <- apply_catch_weighting(
data = your_data,
length_cols = c("8", "9", "10", "11", "12"),
catch_col = "total_catch",
a = 0.0048,
b = 3.067
)
Calculate juvenile proportions:
# Single sample calculation
juv_percent <- calculate_juvenile_percentage(
frequency = c(10, 25, 40, 30, 15), # Frequencies by length
length = c(8, 9, 10, 11, 12), # Length classes
juvenile_limit = 10 # Juvenile threshold
)
# Get length ranges from frequency data
min_length <- get_length_range(
frequency = c(0, 5, 10, 20, 15, 0),
length = c(8, 9, 10, 11, 12, 13),
type = "min"
)
Convert length frequencies to weight estimates:
Create juvenile analysis plots:
# Plot juvenile analysis
juvenile_plot <- plot_juvenile_analysis(
data = your_data,
x_var = "date",
length_cols = c("8", "9", "10", "11", "12"),
plot_type = "bars",
title = "Juvenile Analysis Over Time"
)
# Create comprehensive dashboard
dashboard <- create_fishery_dashboard(
data = complete_data,
date_col = "date",
length_cols = find_columns_by_pattern(complete_data, "^[0-9]")
)
Common parameters for Peruvian species:
Species | a | b | Juvenile Limit (cm) |
---|---|---|---|
Anchoveta | 0.0048 | 3.067 | 12 |
Sardina | 0.0091 | 3.152 | 15 |
Jurel | 0.0079 | 3.089 | 20 |
For parameter recommendations and detailed examples, see the function documentation.
Froese, R. (2006). Cube law, condition factor and weight–length relationships: history, meta-analysis and recommendations. Journal of Applied Ichthyology, 22(4), 241-253. https://doi.org/10.1111/j.1439-0426.2006.00805.x
IMARPE (2020). Protocolo Elaboración de la Tabla de Decisión para la determinación del Límite Máximo Total Permisible por temporada de pesca en la pesquería del stock norte-centro de la anchoveta peruana. IMP-DGIRP/AFDPERP, Edición: 05, Revisión 00, 40p.
These binaries (installable software) and packages are in development.
They may not be fully stable and should be used with caution. We make no claims about them.