Fish Behavior & Gear Selectivity - Rhode Island Sea Grant ...
Fish Behavior & Gear Selectivity - Rhode Island Sea Grant ...
Fish Behavior & Gear Selectivity - Rhode Island Sea Grant ...
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<strong>Fish</strong> <strong>Behavior</strong><br />
&<br />
<strong>Gear</strong> <strong>Selectivity</strong><br />
Laura G. Skrobe<br />
University of <strong>Rhode</strong> <strong>Island</strong><br />
<strong>Rhode</strong> <strong>Island</strong> <strong>Sea</strong> <strong>Grant</strong>
FISH BEHAVIOR<br />
When was it first studied?<br />
How is it studied?<br />
What are some fish reactions?
FISH REACTIONS – TRAWLS<br />
<br />
General Reaction<br />
*See Video Clip 1
FISH BEHAVIOR IN FRONT OF A TRAWL
SAND CLOUD
BURST SWIMMING
ETHOGRAM<br />
Swim oriented forward<br />
Swim oriented aft<br />
Circling<br />
Tumbling<br />
Impinged (webbing)<br />
Resting (water column)<br />
Oriented down
FISH REACTIONS - TRAWLS<br />
<br />
<br />
Optomotor Response<br />
Visual Stimulus<br />
*See Video Clip 2
FISH REACTIONS - TRAWLS<br />
<br />
Orientation<br />
*See Video Clip 3
FISH REACTIONS - TRAWLS<br />
<br />
Rheotaxis<br />
*See Video Clip 4
*See Video Clip 5<br />
FISH REACTIONS - POTS
*See Video Clip 6<br />
LOBSTERS IN POTS
*See Video Clip 7<br />
LOBSTERS IN MOTION
Understanding fish behavior can<br />
lead to more selective fishing gears<br />
Wardle 1989
SELECTIVITY<br />
: a fishing method's ability to<br />
target and capture organisms by<br />
size and species during the<br />
fishing operation allowing nontargets<br />
to be released unharmed
SELECTIVITY<br />
Mesh size<br />
Mesh shape<br />
Hook size<br />
Vent size<br />
Bar spacing<br />
Ring diameter
SELECTIVITY<br />
100%<br />
Retention<br />
100%<br />
0%<br />
15<br />
<strong>Fish</strong> Length<br />
Retention<br />
0%<br />
0 117<br />
<strong>Fish</strong> Length
MESH SELECTION<br />
The retention of the larger sizes by<br />
release of the smaller fish able to<br />
pass through the codend meshes.
MESH SHAPE<br />
Diamond<br />
Square
*See Video Clip 8<br />
<strong>Fish</strong> Escapement
BEHAVIORS
GEAR MODIFICATIONS
GEAR MODIFICATIONS
FISH ESCAPE DESIGNS<br />
<br />
<strong>Fish</strong> shooter<br />
*See Video Clip 9
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