orientation, taxes, movements, and migration. phototaxis (light) geotaxis (gravity) chemotaxis -...
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Orientation, taxes, movements, and migration
phototaxis (light)geotaxis (gravity)chemotaxis
- toward food, conspecifics, mates, offspring- away from predators, extract of human skin
thigmotaxis- substrate – sculpins, gobies, anemone fish- conspecifics – sculpins
rheotaxis (current)electrotaxis, galvanotaxismagnetotaxis – tuna?
kineses - lamprey larvae
Orientation and taxes
Migration
"directed mass movements from one place to another on a regular basis"
Why migrate? (what are the benefits?)
Where/when does it occur?
What are the negative consequences of migration?
So, why migrate anyway?
Explain anadromy vs. catadromy
“(migration) occurs when the gain in fitness from using a second habitat minus the migration costs of moving between habitats exceeds the fitness from staying in only one habitat.”
(Gross 1987)
Why migrate? Habitats for different life history periods vary
But, there are liabilities:energetic costsdrifting (getting lost, or displaced by currents)exposure to predation
Migration
I. Functionfeeding (daily)
follow food abundancebreeding (seasonal)
place offspring in their ideal habitatminimize potential for cannibalism
wintering (seasonal) adjustment to temperature
Migration may be horizontal OR vertical
Migration
II. Timingdaily (usually feeding)
seasonal/annual (wintering and reproduction)
lifetime - ontogenetic (e.g. salmon, lamprey)
Migration
adult feeding area
nursery area spawning area
III. Environment
diadromy: ocean freshanadromy ocean fresh (to breed)catadromy fresh ocean (to breed)
obligate (eel)facultative (sculpin)
amphidromy fresh ocean or ocean fresh…but not for breeding (life cycle)
potamodromy fresh fresh
oceanodromy ocean ocean
Migration
“The contrasting directions of migration can largely be explained by the relative availability of food resources in ocean and freshwater habitats." Gross et al. (1988)
___________________________________________________relative level geographic predominatingof productivity location migratory modeoceans > freshwaters temperate anadromy
latitudes
freshwaters > oceans tropical catadromy latitudes
Migration
Partial migrationvertical migrationanadromous vs. landlocked species
Migration
So…. How do we study migration? Open oceans are large….
Acoustic Telemetry
Tags emit unique signal every 3 mins, for ~ 3 years
Acoustic Telemetry
Receivers deployed singly, or in virtual positioning arrays
Acoustic telemetry array
2012 – fish 29518 (wild male)
2012 – fish 29497 (hatchery male)
