Nature Notes

Volume XIII No. 1 - October, 1947

Visibility Disc Replaced
By O. L. Wallis, Ranger-Naturalist

The white cement disk has been replaced in 25 feet of water in the lake below the Sinnott Memorial to aid the visitors to appreciate and grasp the extreme clarity and deep blue color of the water. One of the binoculars at Sinnott Memorial is trained upon the 24 inch object. Paul Herron, boatman for the Park Company, lifted the disc from its old location, repainted it, and then reinstalled it. Metal legs were attached to one edge so that the disc tilts toward the observation center.

Rainbows In Pools On Wizard Island
By O. L. Wallis, Ranger-Naturalist

Located in the blocky lava on the west side of Wizard Island are situated three pools caused by the unequal flow of volcanic material. Their bottoms are below the surface of Crater Lake so that they are kept filled to the lake level by infiltration. During earlier times when the level of the lake was higher two of the pools were mere inlets.

The temperature of the pools varies 5 to 6 degrees F. warmer than that of the lake water. Green algae and diatoms cover the pool bottoms, and tend to give them a blue-green color when viewed from the Watchman.

The smaller of the pools is Cleetwood Pool, in which lies the remains of the Cleetwood, the boat used for the initial soundings of the lake in 1896. According to Ranger-Naturalist Wayne E. Kartchner in an unpublished report, there were two small rainbow trout located in this pool in 1936. They were again observed in 1937; only one was seen in 1938, and none in 1939. On August 2, 1939, six more fingerlings were planted. Observations this year revealed several fish were still to be found in this pool. They varied from eight to eleven inches.

Emerald Pool, the largest of the small lakes, contains so much aquatic vegetation that it has a definite emerald color, this pool is 150 feet long, 15 feet deep, and 35 feet wide. On visits August 17 and 23, many mayflies, stoneflies, water striders, salamanders, and tadpoles were observed; giving evidence of an abundance of fish food. Three large rainbows, one "as large as one's arm" were seen. Twelve trout were placed in this pool in 1939. At least three of them were taken by anglers in 1946.

The third pool, Rocky Pool, is located on the east side of a high ridge of blocky lava behind Emerald Pool. It is separated from the lake by higher lava barriers than the other pools, and is about 60 feet across. From the 1939 planting, it received six fish but on visits this year no trout were observed.

Two specimens were collected from Cleetwood Pool on August 11 by Ranger-Naturalist Water S. Vincent. Both were male rainbows. The stomach contents of these fish revealed that this pool contains a scarcity of fish food for conifer needles and vegetative matter, mainly diatoms, which have little nutritional value, made up the bulk of the contents.

pools on Wizard Island

Measurement of these fish and stomach contents are:

Specimen No. 470811-1 WI, rainbow, male, standard length: 21.3cm, total length: 24.1cm, weight: 158.3 grams. Stomach contents: 28 insect larvae, 12 shrimp, 750 Daphnia (water flies which are almost microscopic), 1 fragment of crayfish, and 50% vegetative matter (diatoms).

Specimen No. 470811-2 WI, rainbow, male, standard length: 20.2cm, total length: 22.9cm, weight: 126 grams. Stomach contents: 6 insect larvae, 1 terrestrial insect, 22 conifer needles (made up bulk of contents), 275 Daphnia, 10 shrimps, and 25% vegetative material.

This investigation shows that conditions within these pools are suitable for survival of trout.

The 1947 Catch In Crater Lake
By O. L. Wallis, Ranger-Naturalist

To the angler, the fishing in Crater Lake this season proved to be disappointing for a total of only 23 fish taken by boat fishermen during July and August. This total constitutes the lowest catch reported since the creel census began in 1937. To the investigator, the results provided interesting and instructive information about the fish condition in the lake. Fishing boats have been available daily from 7:30 A.M. until 5:30 P.M., from July 15 through September 1. Few people availed themselves of the full day. Most of the fishing was confined to the area around Wizard Island and Skell Channel; few venturing far from this locale.

Information in this report is gleaned from data of boat fishing and a limited amount of shore fishing. Boat operator Paul Herron and his two assistants, Tommy Price and Dick McConkey, gave material help in gathering necessary data.

1. The catch in 1947. Of the 23 fish caught from boats, 14 were silver side salmon and 9 were rainbow trout. This amounts to .21 fish per boat hour, as compared with .11 for 1946. (See Nature Notes, 1946). The silverside averaged 12 inches in length and 8.6 ounces in weight; the rainbows 17.5 inches and 2 pounds 4 ounces respectively. Boats were used for fishing a total of 110.5 hours, only 6.8% of the use made in 1946.

2. Natural Reproduction. Although persistent observations were made during the summer, no sign of fry or fingerlings were seen. Mr. Herron in his 80 trips around the lake never saw any small fish. On July 13, two fishermen from Klamath Falls reported that there were some "six inch rainbows off the Wineglass shore." The size of the silversides would indicate that they had been spawned in the lake.

3. Shore Fishing. As in past seasons, shore fishing is attempted by considerable numbers of improperly equipped with a general lack of success. Three rainbows, 9, 14, and 15 inches, were taken from the south shore at the boat landing and at the Wineglass; no other catches were reported.

4. Food. Only nine stomach samples were obtained throughout the summer; midge larvae, and midge pupae made up the bulk of the silverside stomach contents examined, while three of the rainbow stomachs contained whole salamanders.

5. Age and Growth Determination. Ten scale samples were taken and will be studied during the winter to determine the age groups and growth record.

6. Remarks. Although there is definite evidence that there is some natural reproduction taking place among the silversides, the size of this season's catch would seem to indicate that this natural reproduction is not sufficient to provide satisfactory sport for the visitor. Only by supplementing this reproduction by stocking can fishing be brought back to its former reputation. Stocking the lake is expensive and difficult with relatively small return for the effort of the fisherman.

The 1947 Boat Fishing Record for Crater Lake

Fish taken:JulyAugust 1947
    Silverside salmon 7714
    Rainbow trout 369
    Total 101323

No. of boat reports: 101121

No. of anglers 202343

Total boat fishing hours 51.559110.5

No. of fish per boat per hour .19.22.21

No. of fish per hour per angler .10.12.11

Comparison with 1946 season: only 6.5% as many fishermen took 13.4% as many fish as taken in 1946 with the result that nearly two times as many fish were taken per boat hour this year.

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