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30 THE DISTRIBUTION AND ASPECTS OF THE LIFE HISTORY OF MEDA FULGIDA IN NEW MEXICO. Richard Moore Anderson, New Mexico State University. Investigations were made to determine the distribution and some life history aspects of spikedace, Meda fulgida Girard 1856, in the Gila River drainage of New Mexico. The San Francisco River and its tributaries were sampled 32 times at 24 localities, between March 1976 and September 1977. Spikedace were not found in the San Francisco River during this study, and probably no longer occur there. The reason for the disappearance of spikedace from the San Francisco River appeared to be related to habitat loss and modification. The Gila River and its tributaries were sampled 57 times at 33 localities, between November 1975 and September 1977. The most downstream collection of spikedace was made at Red Rock (1219 m) and the most upstream collection was in Taylor Creek, near the mouth of Beaver Creek (1905 m), 5 km below Wall Lake. However, spikedace were most commonly found between the Lower Middle Box of the Gila River (1305 m) and the lower 2 km of the Middle Fork (1809 m) and up to Tom Moore Canyon in the East Fork (1830 m). The current distribution of spikedace in New Mexico is more restricted than it was 30 years ago. The spikedace preferred shallow (< 30 cm), gravel and rubble- bottomed riffles with moderate to swift current. In years (1975 and 1976) of above average water discharge, year-class strength was much greater than in 1974 when there was a drought i-n the winter and spring months. Most growth occurred in the summer and early fall. No winter growth was observed. In March, the size range of age-1 fish was 35-60 mm and was 63-75 mm for age-2 spikedace. Spikedace were sexually mature at age-1. The spawning season extended from mid-March into May. Age-2 females spawned 3-4 weeks before most age-1 females. Some age-1 and most age-2 females apparently spawned at least twice during the spawning season. Most age-2 fish died during or immediately following their second breeding season. Spikedace fed exclusively. on aquatic insects. Mayflies of the family Beatidae were most commonly utilized along with subimago mayflies. Caddisflies and chironomid (blood worms) larvae were also commonly eaten. Because of their drastic decline in the Gila River in Arizona, spikedace distribution and abundance appears to be affected by habitat modification and competition from the introduced red shiner. Red shiners are presently in the San Francisco River and moving up the Gila River from Arizona into New Mexico. Also activities, such as channelization and dam construction, which reduce the amount of suitable riffle habitat for spikedace, are proposed for the Gila River in New Mexico downstream of Turkey Creek. Channelization, damming and the establishment of the red shiner will probably result in further reductions in the distribution and abundance of spikedace in New Mexico.