Abstract
- Describing and explaining patterns of individual animal behaviors in
situ, and their repeatability over the annual cycle, is an emerging
field in ecology owing largely to advances in tagging technology.
- We describe individual movements of adult Sakhalin taimenParahucho perryi , an endangered salmonid fish, in the
headwaters of a river in northern Japan during the spring spawning
season over two years.
- Migration timing, separated into stages prior to, during, and
following the spawning period, was found to be more consistent and
repeatable for females than males.
- We hypothesized that the observed coordinated movement within seasons,
and repeatability in migration timing across seasons, could result
from 1) individual-specific responsiveness resulting from endogenous,
biological traits that are mediated by environmental factors, or 2)
social interactions among comigrating individuals.
- We found that water temperature and water level experienced by fish
near the river mouth approximately a week before arrival at the
spawning ground explained variability in run timing between years for
females but not males.
- We found no evidence of conspecific attraction or repulsion resulting
from social interactions among the spawners and post-spawners.
- We conclude that individual-specific responsiveness to environmental
cues was the likely mechanism underpinning the observed migration
timing and movement patterns.
- Determining the importance of these environmental and social factors
not only during spawning but also during non-breeding life-history
stages would contribute to a more comprehensive understanding of
migratory connectivity in this species.
KEYWORDS
behavioral repeatability, coordinated movement, environmental cue,
migratory connectivity, Sakhalin taimen, social interaction, spawning
migration