SEASONAL-CHANGES IN THE STONEFLY (PLECOPTERA) COMPONENT OF THE DIET PROFILE OF TROUT IN BIG HUNTING CREEK, MARYLAND, USA

The stonefly (Plecoptera) component of the trout diet profile was stud ied by analyzing 172 stomach pump samples collected between February, 1986, and December, 1989, in Big Hunting Creek, Maryland. Samples were obtained from a naturally reproducing population of brown trout (Salm o trutta) and a stocked population of rainbow trout (Oncorhynchus myki ss) caught between the boundaries of Catoctin Mountain Park and Cunnin gham Falls State Park. Eighty-one of the samples contained a total of 1596 Plecoptera, 88% of which were adults. Twenty species were identif ied representing 7 families and 15 genera, with the dominant species b eing the winter stonefly, Allocapnia nivicola. Approximately 93% of th e Plecoptera were represented by the winter stonefly species Allocapni a nivicola, A. granulata, A. recta, A. rickeri, Paracapnia angulata, a nd Taeniopteryx maura. Recorded as a percentage of the total number of items recovered per month, stoneflies account for 47% (December), 82% (January), 70% (February), and 57% (March) of the items consumed. The se findings demonstrate the importance of stoneflies in the diet of ea stern populations of trout during the winter months.