Orientation, taxes, movements, and migration. phototaxis (light) geotaxis (gravity) chemotaxis - toward food, conspecifics, mates, offspring - away from.

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

GLATOS – Great Lakes Acoustic Telemetry Observation System

Acoustic telemetry array

2012 – fish 29518 (wild male)

2012 – fish 29497 (hatchery male)

Right Whale Listening Network (link)