Transcript Reproduction in fishes

Orientation, taxes, movements, and migration
Orientation and taxes
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, galvanotaxis
magnetotaxis – tuna?
kineses - lamprey larvae
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)
Migration
Why migrate?
Habitats for different life history periods vary
But, there are liabilities:
energetic costs
drifting (getting lost, or displaced by currents)
exposure to predation
Migration
I. Function
feeding (daily)
follow food abundance
breeding (seasonal)
place offspring in their ideal habitat
minimize potential for cannibalism
wintering (seasonal)
adjustment to temperature
Migration may be horizontal OR vertical
Migration
II. Timing
daily (usually feeding)
seasonal/annual (wintering and reproduction)
lifetime - ontogenetic (e.g. salmon, lamprey)
adult feeding area
nursery area
spawning area
Migration
III. Environment
diadromy: ocean
anadromy
catadromy
amphidromy
fresh
ocean
fresh
fresh (to breed)
ocean (to breed)
obligate (eel)
facultative (sculpin)
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
predominating
of productivity
location
migratory mode
oceans > freshwaters
temperate
anadromy
latitudes
freshwaters > oceans
tropical
latitudes
catadromy
Migration
Partial migration
vertical migration
anadromous vs. landlocked species
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)