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<br />4 JOURNAL OF 7'f-~ ARIZONA-NEVADA ACADEMY OF SCIENCE
<br />VOL. 23
<br />Table 2. Absolute (g) and Relative Weights (%) of Fishes Collected in the Lined Coachella Canal, California,
<br />November 1984.
<br />Species Samples (g) Observed 1/ Total (g) g/m2
<br />(est. g)
<br />Canal Section A (2,977m2)
<br />Channel catfish 16,602 - 2/ 16,602 5.577 93.6
<br />Threadfin shad 443 - 443 0.149 2.5
<br />Carp 684 - 684 0.230 3.9
<br />Subtotal 17, 729 - 17, 729 5.956 100.0
<br /> Canal Section B (8,046m2)
<br />Channel catfish 43,465 0 43,465 5.390 88.2
<br />Threadfin shad 258 0 258 0.032 0.5
<br />CazP 5, 533 0 5, 533 0.686 11.2
<br />Subtotal 49,255 0 49,255 6.108 99.9
<br />Canal Section C (10,785m2)
<br />Channel catfish 17,033 1,250 18,283 1.695 99.7
<br />Threadfin shad 37 0 37 0.003 0.2
<br />Red shiner 20 0 20 0.002 0.1
<br />Subtotal 17,090 1,250 18,340 1.700 100.0
<br /> Canal Section D (19,647m2)
<br />Channel catfish 47,701 8,206 55,907 2.846 58.5
<br />Threadfin shad 0 38 38 0.002 Tr. 3/
<br />Care 38,637 0 38,637 1.967 40.4
<br />Red shiner 128 0 128 0.007 0.1
<br />Largemouth bass 940 0 940 0.048 1.0
<br />Subtotal 87,406 8,244 95,650 4.869 100.0
<br />Entire Reach (41,473m2)
<br />Channel catfish 124,801 9,456 134,257 3.237 74.1
<br />Threadfin shad 738 38 876 0.021 0.5
<br />C azP 44,854 0 44,854 1.082 24.8
<br />Red shiner 148 - 148 0.004 0.1
<br />Largemouth bass 940 0 940 0.023 0.5
<br />Totals 171,480 9,494 181,175 4.367 100.0
<br />1/ =Observed counts following seining effort
<br />2/ =Not included in the analysis.
<br />3/ = Tr. Less than 0.05 percent.
<br />Section D. Individual weight averaged 1,381 g/fish.
<br />Only one largemouth bass was collected, and a small
<br />(3-4 cm) Tilapia sp. was observed but evaded capture.
<br />DISCUSSION
<br />One interesting aspect of canal operations is the
<br />option of drainage. This feature provides biologists
<br />the opportunity of approaching absolute measure-
<br />ments of species composition, density, and biomass
<br />of the fish community. In natural, flowing systems,
<br />similar approaches aze virtually unheard of, and
<br />prediction accuracy is dependent upon sample size
<br />and sampling bias. Normally, estimates are associated
<br />with high confidence intervals. These factors were
<br />greatly reduced in this study.
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