Passive Capture Techniques

Fish Harvest and Movement

Passive Capture Techniques

• Fish caught by– Entanglement– Entrapment– Angling gears

• Gear is not moved through the water

Entangling devices

• Fish are snared or tangled in fabric or mesh

• Examples– Gill nets– Trammel nets

Entrapment devices

• Capture fish that go through small openings in gear

• May be more than one opening• Fish can't find their way out• Examples

– Hoop nets– Trap Nets– Lobster Pots

Angling devices

• Use baited hooks on lines• May be unattended• Examples

– Trot lines– Long lines– Jugs and yo-yos

Problems with passive gear

• Gear selectivity - bias for or against certain species, sizes or sexes of fish.

• Example - trap nets catch crappie, but usually not largemouth bass

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Gill Nets - Fish caught by...

• Wedged• Gilled• Tangled

Gill Nets - Construction

• Wall of Netting• Floats, Weights• Anchors, Bouys

• Hanging Ratio• Mesh size (Bar or

stretch)

• They can be a little cumbersome!!

• Common in commercial fisheries

Trammel Nets - Sets

• Same as gill nets

• Standard sets• Floating sets

Angling Gear

• Long lines– Floats, lines drop hooks– Mostly oceanic fisheries

(miles/longline)

On the Farm:

• Working fish on the farm is a daily activity.

• REM: No fish sales = no business!

• Fish must be moved during harvesting, counting, weighing, bagging, transport, etc.

• How do we move them without harm?

• Let’s look, shall we.

Trapping

• Normally, for small orders, fish can be trapped overnight.

• Traps are baited and set the night before, or very early in the AM.

Seines

• Seines (nets) help work a large area quickly (assuming no vegetation).

• Fish are surrounded, crowded and removed to be placed into storage tanks, or counted out, bagged and transported for sale.

Holding

• Once collected fish may be held in vats.

• Again, minimize stress. Watch your fish!

• Tank, vats, or aquaria are used.

Grading

• Grading, or sorting by size is essential to aquaculture sales.

• Because it is a production science, everything must be similar (identical).

• Placing fish in common groups by size, species, or gender assures uniform products at time of sale.

Grading by bar

• Grader bars are useful when you have 1000’s of fish to sort quickly.

Hand Sorting

• Time consuming!

• Close up of fish.

Bagging and Tagging

• Once you’ve got the size and number,• Bag, tag, sell!

Double-bagging

• Fish must be bagged twice, if you suspect they will puncture the bag (catfish).

Fish Bagging Checklist• 1. Label bag.• 2. Bag ¼ filled with water.• 3. Fish in bag!• 4. Compress bag to remove air?• 5. Crimp top and fill bag with pure oxygen.• 6. Remove oxygen line.• 7. Twist top closed. • 8. Wrap top with rubber band/clamp.• 9. Check for leaks, place in shipper!