|
What is Fish Friendly
Fish friendly from what we have seen at the Rapids can be looked at as a two part job.
1. By far the demonstated harmful impact to fish comes from something that initially we thought was not an area of concern - the livebox. The video system removes that from the equation nicely along with all the netting, counting, and releasing methods used. Picture on right shows a chum leaving the video chute and released to a livebox with an open underwater door.
 
2. Next comes the part that is right in our faces as we test fish, such as the visible physical injuries. It is not that difficult to make a wheel many times less harmful in this way to fish. Many of the injuries experienced can be virtually eliminated by putting some extra effort and money in the right places. Later on this page is a discussion on the progression of improvements that have taken us to where we are at present.
Unlike the livebox, which has numbers of studies linking it to negative impacts on salmon, much of this wheel improvement work has only been evaluated by observing the decrease of injuries. The effects of the injuries or their decrease on actual travel rates and mortality have not been evaluated.
Did you see the subsistence fishwheel video on the Rapids Video Project page catching fish. Below on left is a link to a video wheel doing similar. It turns slower, has padding all over, seine mesh sided baskets, plastic coated smooth bed to slid on and well lined up basket and video chutes. Video on right is the fish friendly, non video Tagging wheel used by the USFWS at Rapids and is actually 3 clips in one. This video has a narration on design and operation
(4.78 MB wmv) (3.33 MB wmv)
 
Why Fish Friendly Fish Wheels
Data analyzed from 10 years of chum salmon tagging with and without live boxes, a 3-year radio tag study on live boxes and a number of multiyear tag and recapture studies into the effects of live boxes have led to the following most likely situation:
That tagged chum salmon traveling to upper reaches of the Yukon River caught in some of the most fish friendly fish wheels in Alaska and held in live boxes for relatively small amounts of time and in relatively uncrowded conditions (next to the average test fish wheel) are 7 to 10 times less likely to make it to their spawning grounds than chum not held but immediately released.
Smaller studies looking into the problem (live box oxygen, tissue analysis) and results from a two year sheefish radio tag study have helped to rule out other possibilities or add to the above assumption.
Compounding this problem is two considerations: First that visually chum salmon appear to be one of the least affected by live box holding especially when compared to sheefish and whitefish which are major subsistence food sources and caught often in large numbers incidental to chum or king salmon test fish wheel use. Second that some studies on stress related effects to fish (the ongoing Yukon River Ichthyophonus research for example) show that the greatest effects show up in the last stages of a fish’s life. If chum are 7 to 10 times less likely to make it to the spawning grounds what are the rates for live box held fish that make it but are unable to spawn vigorously for the last two weeks of life on the spawning grounds?
Test fish wheel caught fish can be handled better:
In 1998 35 radio tagged sheefish were caught in a Rapids fish friendly wheel and released with no live box holding time. All were radio tracked to their spawning grounds about 500 km upstream of the Rapids fish wheel site.
Subsistence fishermen in the down river Tanana area have reported greatly reduced rates of tagged fish in their catches since the reducing and eliminating of live box held chum salmon by the Rampart Rapids fall chum tagging project 40 miles upriver.
Fish Friendly Design and Operation Methods
The first considerations started years before fishwheel video came on the scene. They are only needed on test wheels and in no way should subsistence or commercial fishers ever be burdened with the expense and labor of all this. The frequency of many of these injuries may not be that much to a subsistence fisher or observer, but the idea of any consistently repeatable injury caused to test wheel caught fish that are being released was a concern to us. That injuries still happen in the course of monitoring all these fish is a fact. The wheel does not always process them as planned. On the other hand that there may be 1000% less injuries today I’d have little doubt. This is what we think works.
Webbing and No Poles
In 1996 during the first year of the Rampart Rapids Fall Chum Tagging Project concerns about head and nose injuries started the use of a single large section of seine webbing on the sides of the baskets instead of multiple wire and pole sections normally used on subsistence wheels. This was done as an addition to the already wired baskets back then. At present baskets are specifically designed to use just the webbing, and poles are eliminated from the critical areas of the sides. We use heavy #84 latex coated twine with a 3” stretched mesh, which often has to be special ordered. For our size wheels we buy two pieces about 30’ x 6’ with burnt end. They get put on with little cutting and excess often just hangs. It’s expensive.
The need for this is because when fish realize they are about to be caught just before the basket comes out of the water a normal reaction is to turn and dart at right angles to their upriver direction of travel. This is usually towards the outside of the basket and deeper water. As a fishwheel fisher of 30 years I can attest to the amount of damage and broken wire on the sides of the basket as compared to any other part. The fish often hit so hard you can tell one is about to be caught just by the sound of impact. This is a sound I only hear on other wheels now. Noses were cut open on the wire and basically broke apart when hitting a pole. This was by far the most noticeable impact we were having on the fish.
In the pictures you see heavy poles framing the basket sides allowing webbing to be applied over a large area without the need for pole bracing. Problems with webbing are that when first put on it stretches considerably when wet. Also staples that are the normal way to apply wire wear through nylon webbing from all the “working” of the flexible webbing as the basket rotates. Finally once stapled, how do you tighten up now loose webbing after a week of use?
Large headed roofing nails (see picture) placed on the backside of the framing poles but left protruding enough to get the webbing under allow a secure non wearing attachment. The webbing is only attached at its perimeter. The webbing can also be slipped of the nails and tightened in little time. An added benefit is the ability to take all the webbing off after years of use and repair and dip it in more protective coating. Each basket is one large piece and removal can take only say 10 minutes. I liken the look and action of the baskets to a playpen with trampoline sides.
The 3 basket wheel with webbing sides in the below pictures and at other places in this web site was built by Bill Fliris, past project manager of the Tanana 5A test fishwheel. His project was the first wheel the Rapids video system was exported to. He is an innovative guy and the wheel below was designed from scratch to be fish friendly and withstand the increased wear a test wheel gets. See his reports and appendix on building the 5A fish friendly fishwheel on the Reports page. The project is currently run by Pat Moore of Tanana using the same basic design of wheel with improvements of his own.
   
Fishwheel Basket Bed
This area of the baskets has a different fish friendly function than the sides. Fish don’t seem to “hit” it or if they do it’s at a normal slow travel speed and is of no concern. The problem here was that it is the part the fish slide on, and on the early test wheels there were often wire ends and nails protruding, large mesh wire that hooked the gill covers of especially whitefish (chain link fencing was especially bad), and surfaces that did not allow immediate movement of the fish to the basket chute. Sagging and stretched out seine webbing applied with staples was especially bad here as it bagged up and held the fish till the basket got almost vertical and then dropped the fish with a thud to the basket chute causing bloody gills.
What you want is immediate smooth movement of the fish out of the basket bed area and into the basket chute before the basket even starts to rise up high. We went through a lot of materials over the years. Heavy HMW plastic 1 ½ inch square mesh was used for about 5 years on three wheels till the poor durability and hooking of gill covers got to us. What is used now is 1” x 1” vinyl coated welded wire specially made for durability and shipped from the Seattle (crab and lobster pot wire). It’s expensive but it’s almost impossible for us to find anything but poorly welded bare steel wire in Alaska today. Got 4 years on one wheel with it and not a single weld broken yet. A friend with a subsistence wheel used it for bed and siding on his wheel baskets and had similar results on the basket bed but had side welds breaking after 2 years. As stated before the fish hit those sides hard.
Speed of Basket Rotation
Much is made of this issue with some saying fast wheels catch more fish and others pointing out some of the best catching wheels they ever saw were moving slowly. One thing that doesn’t matter is the revolutions per minute which you often hear as describing wheel operation. A small diameter wheel turning fast often has the leading and catching part of the basket moving through the water at no greater speed than a larger slow revolving wheel.
All that being said what we have found is that a slow revolving wheel is best for a number of reasons. In the Rapids area we have wheels operating at different speeds and something that myself and other fishers have noted is that the slower the wheel picks up the fish the less they react to being caught. Also the slower the basket rises the more time the fish has to slide towards the basket chute and less chance it will be lifted high while still in the basket and fall hard into the chute.
Finally test fishwheels turn 12 to 24 hours a day. The wear in some places is something a normal wheel doesn’t ever see. “Speed costs money how fast you want to go” is something a snow machine mechanic friend used to say and I think it applies here. We want to keep them running and minimize the accidents and down time. As long as they are turning relatively the same, day after day it doesn’t matter if they could catch more if run faster or slower. What we want is the same from day to day in test fishing.
In the pictures you see plywood panels or paddle boards tied on to poles between each basket. Normally a wheel would have boards nailed semi permanent to these poles and only be changed if rotation speed was extremely fast or slow. These removable paddles are all sizes and are changed throughout the season depending on current speed which does vary a good bit. They are easily tied on with loose knots and have the added benefit of not creating any drag coming out of the water. Tarps are even added right on the baskets in extreme low water found some fall seasons. The best rotation I have found for the fish is described as “just a little faster than a stall”.
Padded Chutes
This one is simple; you put padding on anything the fish come in contact with. We use different types in different places and have found some pretty tough materials for use in places that get lots of wear. Some of this tough stuff is very expensive and we’re finding new stuff all the time. On the large areas like the basket chutes I use a gallon of contact cement for one wheel to apply it all. For smaller tight areas I have spray cans of contact type cement and use cheaper closed cell sleeping pad foam.
One area of big improvement that I actually have records of is the padding of the basket chutes. This was not tried until the video project started in 2000. Fish moving down the basket chute often get into a swing the head and slap the tail mode. Think about it; you hit your head on bare boards a few times or you hit your head on boards covered with 5/16” foam. Anyway prior to this I would get a bloody gill on about one Chinook salmon a day, as seen in the video, with about 25 to 50 caught in an average 12 hour counting period. The first year we lined the basket chutes I went over 350 Chinook before I saw one.
Note: We also did some testing on gill bleeding where we marked a few that had impact bleeding but not torn gills. These were put in the live box, and when hours later were removed, had stopped bleeding. Prior to this most of us thought fish did not recover from this. A scientific, statistically valid study it was not but it did indicate something to us on this issue.
.
 
Video Chute Construction and Alignment
After the fish come out of the revolving basket chute they slide into the stationary video chute. This video chute has foam padded plywood sides and a 3/16” white UHMW plastic bottom for photography and easy sliding purposes. The first video chute was solid and framed and rested firmly in its place. The fish hit it and it gave little.
At present the video chute is attached and rests on a 10’ long small flexible spruce pole perpendicular to the chute (picture). It is attached to uprights at both ends and allows for raising and lowering the chute entrance to match up to the basket chutes if the axle of the fish wheel needs to be raised or lowered. This alignment is critical. If not aligned the fish drop from the basket chute to the video chute and fall on the unpadded plastic bottom. On some test wheels this is a considerable distance. Also the chute being on the flexible pole allows the chute to give vertically and bounce if hit hard.
The present video chute has the plastic bed suspended between it’s attachment on opposite sides much like a drum head. The plywood sides are attached at the bottom only and have no framing except at the exit so they bend outward easily. When a big Chinook hits the video chute all the looseness can make a racket and the chute gives this way and that but nothing is that solid so hopefully the fish is fine and on its way upriver. The idea is reducing the impact with simple construction techniques and considerations. First picture below is a non video Tagging wheel chute.
Visit the Reports / Capture Mortality page for studies and more info on above
“So Fish Friendly the Fish Come Back for More”
|
