Trammel Nets

Description

Example of a Trammel Net
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Trammel nets are like gill nets, but they are made of three parallel vertical mesh panels instead of just one. The two outer panels are larger mesh, and the inner panel is composed of smaller-sized mesh. The inner panel has greater depth than the outer panels. Meshes can be made of either monofilament or multifilament or the inner composed of monofilament and the outer multifilament. All panels are sewn to a top and bottom framing line (optimally) or float line on top and a lead line on the bottom. Fishes are captured by entanglement, that is, fish become wrapped in the mesh or caught by a body part (dorsal spine, opercular spine, mouth, etc.). This module emphasizes drifting, benthic trammel nets.

TypePassive (when set in a stationary position) or Active (if drifted or used to encircle), Entanglement gear
Habitat deployedDiverse habitats of both lakes and streams/rivers, near shore and in open-water (pelagic) zones. Stationary sets may be benthic, mid-water, or near surface. Drifting trammel net passes in rivers are either positioned to move along the bottom or near the surface.
Target speciesWide variety of larger bodied, juvenile and adult warmwater and coldwater freshwater fishes. Drifting trammel nets in rivers can capture sturgeon, suckers, buffaloes, carpsuckers, perch, common carp, freshwater drum, and catfish.

Trammel Net Anatomy

Trammel Net Anatomy
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Standard Trammel Net (weights may be added for benthic sets or higher current situations when drifting, floats may be added for drift sampling)

Trammel net and gill net designs have similarities. Refer to the “Gill Net module” for additional design and anatomy specifics shared between the two types of nets.

Common sizes, Materials, Mesh size of drifting benthic trammel nets

  1. The American Fisheries Society standard nets used for benthic riverine sampling is:
    1. Length 305 m (100 ft);
    2. Inner-panel 2.4 m (8 ft) depth, 2.5 cm (1 in) square bar mesh, #139 multifilament nylon netting; note that monofilament inner panel netting may increase catch rates;
    3. Outer-panel 1.8 m (6 ft) depth, 20.3 cm (8 in) square bar mesh, #9 multifilament nylon netting;
    4. Float line 9.5-12.7 mm (3/8-1/2 in) diameter braided poly foam core; and
    5. Lead line 6.4 mm (1/4 in) diameter, 13.6 kg (30 lb).
  2. Deployment gear includes two floats, a 15- to 20-m rope tied to each float and attached to the float line ends of the trammel net, and additional weights that can be attached to the lead line if high current velocities warrant such weight.

How trammel nets catch fish

Trammel nets are classified an entanglement gear, so fish capture is accomplished by some form of entanglement. Trammel nets have two primary modes of capture, “bagged” and “gilled”.

Fish encountering the net can swim through one of the outer panels, run into the small-mesh middle panel, propel forward, and push the small-mesh inner panel through the other large-mesh outer panel. When this occurs, a bag of small mesh containing the fish is protruded through the large mesh, and the fish is “bagged.” Otherwise, like gill nets, individuals may be entangled by spines or hard structures in the smaller mesh panel (“gilled”).

This series of three stages illustrate the process of capturing a fish by “bagging” in a trammel net.
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This series of three stages illustrate the process of capturing a fish by “bagging” in a trammel net.

Relationship to another entanglement gear, the Trammel Net.
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Trammel vs. Gill Net Functionality

Relationship to another entanglement gear, the Gill Net

VIDEO: https://youtu.be/OJnXUgg-NEM

Gill Net and Trammel Net Storage Tips
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Gill Net and Trammel Net Storage Tips

VIDEO LINK: https://youtu.be/npbLN47XMb0

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Quick Repairs- Tools, Twines, and Repair Methods: See Repairing Nets Module

Replacement rules 

Fisheries offices may and should have guidelines on when to replace a Trammel net.One example specifies that if a gillnet has a minimum of 25% of the netting area torn, then replace the net.

Field Methods

Drift length: 
A common or standard sampling length in rivers is 100-300 m (328 – 984 ft).

How deployed:
Horizontal sets may be stationary or drifting, on the bottom (benthic) or suspended near the surface (pelagic).Deployed in flowing rivers and streams as well as still waters of lakes and reservoirs.

Definitions: See Gill Net module

Anatomy, materials, how Trammel nets operate

Introduction to Trammel Nets
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Trammel Net Introduction 

Introduction to Trammel Nets

VIDEO LINK: https://youtu.be/EmzPaVtYRps

Different sizes and advantages, advice
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Trammel Net Sizing and Implications

Different sizes and advantages, advice

VIDEO LINK:https://youtu.be/sPg16K8zDiI

Dyeing nets
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Dyeing Entanglement Nets

Dyeing nets

VIDEO LINK:https://youtu.be/DM_0Xw6iolA

How a drifting trammel net operates on ridged, uneven sandy bottoms, including modifications to increase catch as by adding weights and hobbling. 
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Hobbling Techniques for Drifting Trammel Nets

How a drifting trammel net operates on ridged, uneven sandy bottoms, including modifications to increase catch as by adding weights and hobbling. Also, net drifting directions relative to bottom sandy ridges

VIDEO LINK:https://youtu.be/2KhQMAFCwk0

Field Methods, Deployment and Retrieval

Trammel Net (drifting) preparation for deployment
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Preparing to Deploy a Trammel Net

Trammel Net (drifting) preparation for deployment

VIDEO LINK:https://youtu.be/WKJTXtNi4MY

Trammel Net (drifting) deployment and retrieval with snag removals
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Trammel Net (drifting) deployment and retrieval 1

Trammel Net (drifting) deployment and retrieval with snag removals

VIDEO LINK: https://youtu.be/jKdAGaBrMfA

Trammel Net (drifting) deployment and retrieval
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Trammel Net (drifting) deployment and retrieval 2

Trammel Net (drifting) deployment and retrieval

VIDEO LINK: https://youtu.be/EkrHtO-Lh9Y