Technological Solution to Reduce by Catch

8/8/2019 Technological Solution to Reduce by Catch

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Technological solution toreduce by catch


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Sonar Devices

Dual-frequency IDentification SONar

(DIDSON) Modification on trawl net

high frequency (1.0 and 1.8 MHz)

provides images with sufficient resolution toclearly distinguish the shapes of individual

fish at an update rate (4 - 21 frames per

second) that allows tracking between

images.


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The sonar has a small enough size (30.7 x

20.6 x 17.1 cm) to be deployed flexibly andeffectively protected.

It can be operated in real time with a cable

or, with a battery pack and recorder,

remotely deployed.


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Sector imaged by sonar

Trawl Net (cylinder)

Sonar

Figure 1. Orientation of DIDSON sonar and the area that it imaged on the trawl

net.


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S

S

S

P

P

P P

P

Figure 2.- Pollock (P) and salmon (S) in a pelagic trawl, imaged by a DIDSON sonar


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Turtle Excluder Devices (TEDs)

A modification to the trawl net that allow

larger animals to escape after being takeninto the net

TEDs are usually fitted into a trawl net at the

beginning of the codend.


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At this point in the net, water-flow is fastest

and maximizes the ability of a TED toseparate target animals, such as prawns and

scallops, from non-target animals, such as

sea turtles.


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Medina Panels

Constructed of fine mesh webbing, sewn into

the upper part of the purse seine netprotected dolphins from becoming tangled.

Usually it is one or two strips deep and 330

m long.

The longer Medina panel the more effective it

is, especially fitted into the net throughout the

bunches area and as near the bunt as

practical.


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Other efforts

International Smart GearCompetition by

World Wide Fund.1st prize -Duke University researchers

2nd prize -Chemist Norm Holy from

Pennsylvania, fisheries biologist Ed Trippel

from Canada, and fisherman Don King from

Massachusetts

3rd prize -Central Institute of Fisheries

Technology in India


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1st prize

using Beverly's new weighted, deep-set gear

weigh down the main line with lead weightsand release or "set" the baited hooks at

depths deeper than 100 meters (328 feet),

which allows longline fishermen to minimize

encounters with sea turtles while maximizingtheir tuna catch


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2nd prize

developed gear to help marine mammals

detect and avoid gillnets before coming intocontact with them as well as allow them to

escape unharmed if they still become

entangled.

combination of glowing ropes and stiffer nets

To create avoidable, detectable, safer gear,

the team tinkered with the chemical

properties of the ropes.


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3rd prize

reduce the bycatch ofjuvenile shrimp and

fish in shrimp trawls developed a system of angled metal grids

and net meshes that catches and sortsmature shrimp and finfish while allowing

juvenile shrimp and fish to swim awayunharmed.

Sorting mature shrimp and finfish betweenthe lower and upper parts of the net helps toreduce the time the trawler crew spendssorting on deck.


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Location of Excluder

Salmon excluder


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Cont. others

Nordmore grates

Halibut excluders Net mesh/selection grates

Tori line

Weighted lines

Rely on differences in bodyshapes

Bird scaring


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Technological solution to reduce by

catch in Malaysia

Less in Malaysia because of:-

-high cost-not really introduced in Malaysia

-fisherman attitude


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Conclusion

Technological solution to reduce bycatch of

fishes is still less all around the world.


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Thank you

Technological Solution to Reduce by Catch

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