(PRWEB) February 08, 2006
(PRWEB) February 8, 2006 -- Bycatch, Shakers, and Wastage Among Seiners, Gillnetters, and Trollers. Max Ledbetter reprints and corrects some misconceptions and outlines historical wastage caused by premature catch.
Early in the spring of 1981 a lot of attention was focussed on a one-page memo labelled (dramatically) as the "Ledbetter Report." As the factions within the British Columbia fishery continued to position, this little piece of paper was constantly misquoted. No surprise: how could the people involved in the fishery state the correct facts about the memo? They did not possess a copy.
The original title of the "Ledbetter Report" is "Summary of immature spring salmon seine catches." (Another name for the chinook salmon is spring salmon.) The memo was written for the biologists within the Department of Fisheries and Oceans, Canada. It summarized data taken on five boats in British Columbia during the 1980 salmon season and provided an estimate of the total bycatch of juvenile chinook salmon by the B.C. seine fleet. The data indicated that the salmon seiners catch fewer juvenile chinooks than previously thought. Although the results stated in the memo are inconclusive, the data certainly showed that the seine bycatch is not a big part of the Fraser River chinook problem: the seine juvenile spring catch will only contribute 2000 - 5000 adult spawners to the Fraser system (2 - 5% of the present escapement).
If we look at the data from another angle, it becomes apparent that the value of the bycatch of juvenile springs is realized at later stages of growth in the catches of the other gear types. The present loss of catch value stimulated an unsolicited proposal by Redden Net Co. to find the best net design and mesh size/style combination for reducing the juvenile chinook bycatch. Although individuals within the Department of Fisheries and Oceans encouraged this attempt to obtain funds from the Department of Supply and Services, the D.F.O. opted for an in-house, small-scale survey (for reasons that have still not been made clear).
Finally, in an attempt to place all available data on salmon wastage in proper perspective, the Fishing Vessel Owners Association asked me to write an appendix for their submission to the Commission on Pacific Fishery Policy. The title of their appendix is "A preliminary analysis of the loss of salmon revenue due to present gear technology and deployment, 1975 - 1978." This small paper summarized recent data and analyses published in the scientific literature and presented the data in terms of the potential value of wasted salmon poundage.
The potential values of the sport, troll and seine shakers are summarized below.
Potential, Annual Values of Wasted Juvenile Salmon (millions of dollars)
chinook coho total
sports 1.3 1.4 2.7
seine 3.6 -- 3.6
troll 3.5 3.0 6.5
These results illustrate that the sport, troll and seine fishermen are in the same boat.
The appendix included another problem -- the effects of the troll and gillnet fisheries on the size of the salmon. The data concerning the decrease in size of salmon was taken from publications by Dr. W. E. Ricker (a pioneer of fisheries management science). Ricker presented a great deal of positive and negative evidence for his theory that the catch of larger fish by troll and gillnet gears has caused genetic deterioration within the salmon stocks, leading to reduced salmon sizes. The appendix stated Ricker's data in terms of dollar and cents.
Estimated Average Annual Loss of Salmon Revenue Due to the Decreasing Size of the Fish, 1975 - 1978, (all other things being equal)
(millions of dollars)
coho pinks chum total
12 13 3 28
We must realize that Dr. Ricker's theory cannot be proved or disproved. The direct effects of gear selectivity and environmental factors cannot be separated at this time. Scientists (studying this type of problem -- with this type of data) can only look at time trends, create theories, provide evidence for or against these theories, stimulate changes in management (for example, smaller gillnet mesh sizes) and then look at the time trends many cycles down the road. A single season (one data point) does not tell us much about the resource.
At this moment, it appears that the shaker mortalities combined with the reduced size of the salmon (which is attributed to the fact that gillnets and trolls have caught the largest fish over the past decades) produces an annual wastage equal to 20% of the total annual commercial salmon wholesale value (a wastage of 59 million dollars in 1978).
We all realize that the important problems within the salmon fishery are increasing the supply of fish and reducing the size of the fleet. And progress in that direction will involve a tradeoff between the fish, efficiency and lifestyle. But the smaller problems such as wastage can be partially solved today. The fishermen must supply suggestions concerning spot closures for juvenile salmon, hook designs and mesh sizes -- bringing us to the largest problem of them all: communication between the different fishermen groups and the government.
See http://ledbetter.freepgs.com/bycatchwastage.html for the citation.