Table 1 Explanatory variables included in statistical analysis. Names in the second column match Fig. 3

Spatial

Location (UTM X and Y)

Easting and northing of receiver in UTM zone 10

Shoreline distance

Distance (km) to coastline

Bottom depth

Mean depth (m) of seafloor

Bottom slope

Mean slope (\(^{\circ }\)) of seafloor

Temporal

Year Day (1 and 2)

Calendar day converted to two variables representing cyclical process

Lunar cycle

Proportion of moon illuminated (0-1)

Day-night

Whether detection occurred after sunrise and before sunset or not

Oceanographic

Temperature

Sea surface temperature (\(\hbox {C}^{\circ }\))

Hor. Current 1

Horizontal momentum (m/s) in N-S direction

Hor. Current 2

Horizontal momentum (m/s) in E-W direction

Vert. Current

Vertical momentum (m/s)

Zooplankton

Zooplankton concentration (\(\frac{\text { mmol N} }{\text { m }^3})\)

Oxygen

Dissolved oxygen concentration (\(\frac{\text { mmol O} }{\text { m }^3})\)

Thermocline depth

Mixed layer depth (m) based on vertical temperature profiles

Individual

Size

Fork length when tagged (cm)

Lipid content

Converted whole body lipid content (% wet weight)

Maturity

Probability that an individual will mature in the same year as detection event