Reproduction in fishes

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Orientation, taxes, movements, and migration
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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
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Migration "directed mass movements from one
place to another on a regular basis"
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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
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(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)
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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
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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
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Migration
II. Timing daily (usually feeding) seasonal/an
nual (wintering and reproduction) lifetime -
ontogenetic (e.g. salmon, lamprey)
adult feeding area
spawning area
nursery area
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Migration
III. Environment diadromy ocean
fresh anadromy 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
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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 gt freshwaters
temperate anadromy
latitudes freshwaters gt oceans
tropical catadromy latitudes
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Migration
Partial migration vertical migration anadromous
vs. landlocked species
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So. How do we study migration? Open oceans are
large.
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Acoustic Telemetry
Tags emit unique signal every 3 mins, for 3
years
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Acoustic Telemetry
Receivers deployed singly, or in virtual
positioning arrays
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GLATOS Great Lakes Acoustic Telemetry
Observation System
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Acoustic telemetry array
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2012 fish 29518 (wild male)
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2012 fish 29497 (hatchery male)
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Right Whale Listening Network (link)