Brode also collected and identified numerous aquatic organisms, including fish, amphibians (frogs and salamanders), insects, plankton, and benthic (bottom-dwelling) invertebrates. He conducted stomach analyses on 224 rainbow trout and coho salmon, reporting, for example, that one trout stomach contained "one blue-bottle fly, one ichneumon fly, 335 flying ants, two grasshoppers, one click beetle, one long-horned beetle and one iridescent beetle" and that another contained 7,500 Daphnia. Brode compiled the original species list for Crater Lake, which contained many plant and animal types never before reported for the lake. The list included species of green and blue-green algae, aquatic moss, a flowering plant (water buttercup), zooplankton (rotifers, crustaceans, amphipods), leeches, sponges, flatworms, aquatic earthworms, snails, crayfish, and various aquatic insects (caddis flies, midge flies, stone flies, beetles, water striders, and springtails). By integrating his biological information with some of the lake's physical attributes-depth, temperature gradient, and sunlight penetration-Brode formulated the first conceptual model of the lake's complex ecosystem in 1938. (17)

Brode was followed by Arthur Hasler, a professor at the University of Wisconsin and a summertime ranger-naturalist at Crater Lake. Although Hasler was interested primarily in the lake's fish populations, he routinely recorded temperature gradients and Secchi depths during the summers of 1937 through 1940. Using an Ekman dredge, Hasler collected green mosses growing on the bottom at a depth of 394 feet, which he referred to as his "most startling biological finding at Crater Lake." Hasler was assisted by Donald Farner, a ranger-naturalist who became a distinguished avian ecologist at Washington State University in Pullman. The two scientists collaborated on one of the first research papers concerning fish production and management in Crater Lake, which appeared in a 1942 issue of the Journal of Wildlife Management. (18)

Even though Brode and Hasler contributed new information about the limnology of Crater Lake, both investigators focused their attention on the lake's fish populations. Prior to 1888, the lake ' presumably had no fish. In late August 1888, William Steel, S. S. Nicoline, and E. D. Dewart transported six hundred fingerling rainbow trout to the lake from a ranch forty-one miles away The thirty-seven trout that survived the trip were planted in the lake on September 1. The first trout-some measuring thirty inches in length-were caught in 1901. Beginning in 1910, the National Park Service officially stocked the lake with fish, including coho salmon (Oncorhynchus kisutch), rainbow trout (Salmo gairdnerii), and brown trout (Salmo trutta). (19)

Arthur Hasler, second from left, poses with other ranger-naturalists and park employees at Crater Lake National Park on June 29, 1938. Photo courtesy of the National Park Service