Selective Fish Harvesting

Design

Some of the design features incorporated in the new fishwheel structure include:

  • The use of aluminum pipe to form the ribbing of the basket - this provided a lightweight yet strong framework for the fishwheel baskets. Former fishwheel baskets constructed of wood did not stand up to the strong water flows through the canyon.

  • Both a welded structure and a "clamped" structure were evaluated. It was decided to go with the "Gee Clamps" as fastening the components using the special clamps allowed easy assembly of the fishwheel at the remote site. These strong clamps (made from galvanized steel) are attached to the piping using set screws and are designed to provide maximum strength at the joints.

  • Knotless webbing on all the basket ribbing to help minimize any damage to the fish caught in the fishwheel.

  • High tension aircraft cable used to stiffen the basket ribbing and transmit forces from one basket to the next to reduce stress on the structure.

  • Plastic plugs used at the ends of the aluminum piping to reduce noise as the baskets rotate in the water.

  • New axels were designed for the fishwheels. One design allowed for the collapsing of one basket on top of the other for transportation while the other used the clamps to attach the baskets to an aluminum axle.

  • Baskets were constructed of different sizes - one fishwheel was fitted with eight foot wide baskets and the other fishwheel was fitted with ten foot wide baskets.

  • The pontoons of the fishwheels were also modified. Modifications were made to meet Workers Compensation (WCB) requirements ie safety railings around the fishwheel baskets. New tow points were attached to allow for better control of the fishwheel pontoons, while being towed and to keep the pontoons from "plowing" into the water as they are being towed.

  • The live boxes on the fishwheels were modified so that they would be attached to the outside of the pontoons rather than the center of the pontoons. Hinges were designed and installed which allowed the boxes to be tilted up on the deck of the pontoons for towing purposes. Having the live boxes on the outside allowed a greater worker area on deck when dipping the fish out of the lives boxes.

Lead design for fishwheel and fishtrap - construction and installation

Project Leader Willy MacKenzie with fish wheel while under constructionThe leads for both the fishtrap and fishwheel was designed to resemble a square funnel with an opening measuring 10.1 m. by 6.8 m. This funnel is gradually reduced to an exit area measuring 2.7m. by 2.6m. that directs the migrating fish into the selective fishing apparatus. The lead is made up of a bottom frame constructed from 1 ¼” aluminum pipe. The aluminum pipe provides the required stiffness and strength required to maintain its required shape in the river current. Using aluminum pipe also offers a product that is light and allows the lead to be detached and removed from the water in the event of high water conditions. Details of the lead design are shown on drawings contained in Appendix “D”.

The lead was designed to be collapsible. Knotless mesh was used on the frame and also attached to form the sides of the lead. Two-inch seine mesh was attached to the bottom and sides using ¼” (6 mm.) nylon twine. A cork line was attached along the perimeter of the top section forming the walls of the lead with orange bladders attached to the ends of the leads as a safety factor for pleasure boats using the Skeena River.

Fish WheelOnce the lead was brought to the fishtrap and fishwheel, the narrow end was directed between the pontoons and underneath the work platform. The lead was then attached to the fishtrap using 3/8” U-bolts. The whole lead structure was placed in the water thus sinking the wide end of the lead to its prescribed depth and angle, with the cork line maintaining the walls in an upright manner. Orange bladders were then attached to the ends of the lead as a safety factor for pleasure boats navigating the Skeena River.


The fishtrap was constructed of 1 ¼ “ aluminum pipe with Kee Clamps used as fasteners to hold the pipe together. The mesh used for the fishtrap included 1” chicken wire as knotless webbing was not made available to the project from suppliers. The fishtrap structure measuring twenty meters in length, three meters in width and four meters in depth was attached to two aluminum pontoons measuring one meter wide, forty-five centimeters in depth and nine meters in length. The fishtrap was lowered and raised from the water by means of small winches attached to uprights on the pontoons. The fish were directed into the fishtrap by means of a fishlead. Once inside the trap the fish were funneled into a holding pen that could be raised to remove the caught fish. It should be noted that the fishtrap and holding pens served as live tanks that could be used for survivability testing of fish caught by selective means.

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