Krill Swarm Sandbox

Total biomass

Whole-area density

Abundance

Mean krill TL

Swarms

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Set up the scenario at left, then press Generate field .

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Swarm parameters, characteristics and estimates download this category (ZIP)

Figures
Tables

Swarm plan view PNG

Column density surface PNG

Swarm dimensions PNG

Biomass per swarm PNG

Distance between swarms PNG

Swarm depth PNG

Sensitivity to swarm parameters PNG

Parameter ranking PNG

Swarm summary CSV

Table 1: standard parameters CSV

Full swarm table CSV

Table 2: sensitivity grid CSV

Table 3: parameter ranking CSV

Krill parameters, characteristics and estimates download this category (ZIP)

Figures
Tables

Length-frequency distribution PNG

Length by age cohort PNG

Packing density PNG

Sex ratio PNG

Growth variants PNG

Krill summary CSV

Length-frequency table CSV

Growth parameters CSV

Transect parameters, characteristics and estimates download this category (ZIP)

Figures
Tables

Krill along the transect lines PNG

Density per transect PNG

Biomass against spacing PNG

Accuracy against spacing PNG

Survey estimate CSV

Per-transect table CSV

Per-section table CSV

Table 4: spacing summary CSV

3D view

A SECTION of the volume at the model's true 1 m resolution: cells with a krill density of at least 1 g/m3 are drawn as exactly-touching 1 m cubes coloured white (low) to red (high) density; sparser cells and empty water are fully transparent. The inset (top-left) shows the full cube at lower resolution with the displayed section in green. Move the section with the sliders. Drag to rotate, scroll to zoom, or nudge the view with the pad (centre dot resets).

Section centre x (m)

Section centre y (m)

Section centre depth (m)

Section size (m)

full volume (coarse) - green = section shown

Abstract 1852 x 1852 x 500 m volume (1 nm2 = 3.43 km2), no geography. Create a scenario, generate the field, and review the results. Real management units are the FULL MODEL, a separate app.

Create the scenario by

Total biomass (tonnes)

Average density (g/m2)

Swarm characteristics

Total biomass for the area (tonnes)

Swarm structure: 60% coastal / 40% oceanic. Average density, abundance and swarm count are derived and shown at left.

Average column density (g/m2)

Spatial SD (g/m2)

Swarm structure: 60% coastal / 40% oceanic. Total biomass, abundance and swarm count are derived and shown at left.

Swarm geometry (m)

Length mean

Length SD

Width mean

Width SD

Height mean

Height SD

Centre depth mean

Centre depth SD

Density & krill length

Density mean (g/m3)

Density SD (g/m3)

Krill mean TL (mm)

Krill TL SD (mm)

Number of swarms

Random seed

Swarm settings

Swarm clustering

Clustering index (daughters per parent)

Cluster radius (m)

Sequential parent/daughter placement. An index of 0 gives uniform random positions; the radius is the scatter SD of daughters about their parent.

Swarm geometry and density

Lognormal means and SDs, by bathymetric stratum. Defaults are the literature priors; the coastal/oceanic split is set by the depth breakpoint above.

Coastal mean

Coastal SD

Oceanic mean

Oceanic SD

Length (m)

Width (m)

Height (m)

Centre depth (m)

Internal density (g/m3)

Krill settings

Krill growth

Growth variant

Von Bertalanffy (basal curve)

Linf (mm)

k

t0 (yr)

Basal curve after Thannassekos et al. 2021 (SC-CAMLR SAM-2021/12, GRYM 48.1). The sex-specific variant uses Kawaguchi et al. 2007 (MEPS 345: 199-210) and is fixed by that source, so its coefficients are not editable here.

Cohort mix

Relative frequency of each age cohort. Renormalised, so only the ratios matter.

Small (1-2 yr)

Medium (3-5 yr)

Old (4-6 yr)

Sex ratio and length-weight

Proportion male

Between-swarm SD

Beta-distributed per swarm. Length-weight is fixed at Skaret et al. 2023: W = 2.236e-6 x TL^3.314 (TL in mm, W in g). A sex-specific length-weight variant is not implemented -- no sex-resolved coefficients have been sourced.

Survey (swath transect)

Swath width (m)

Depth cap (m)

Transect spacing (nm)

Along-track step (m)

The transect sweeps the full length of the area in a band of the chosen width, integrating krill from the surface to the depth cap (or the seabed). Each along-track step is one reported sample: its footprint is width x step, so density is footprint biomass divided by that area (g/m2) and abundance is krill per m2. At a 2 m width and 1 m step the footprint is 2 m2, i.e. density = biomass/2.

Build: 2026-09-02 16:11 UTC

Computed for this scenario