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Thursday, June 7, 2007 - 8:30 AM
350
Relating Fish Abundance and Condition to Environmental Factors in Desert Sinkholes
Kristin M. Swaim and Wiebke J. Boeing. Fishery and Wildlife Sciences, New Mexico State University, 2980 S. Espina, Knox Hall 132, P.O. Box 30003, MSC 4901, Las Cruces, NM 88003
When relating fish populations to environmental variables, numerous studies have utilized a multiple-lake approach. These studies have largely been performed in north-temperate locations. Although some multi-lake studies have been conducted on tropical lakes, information on other warmwater fish communities, like desert species, is lacking due to scarce water resources and the rarity of multiple lakes within a relatively confined geographic region. We hypothesized that fish abundance is primarily determined by abiotic factors, as these can have extreme values in desert environments. We investigated abundance (mark-recapture and catch-per-unit-effort estimates) and condition (length-weight relationship) in 23 sinkholes in New Mexico and correlated those factors to physical, chemical, and biological factors. The sinkholes are located within a few square kilometers on Bitter Lake National Wildlife Refuge and provide habitat for 6 native fish species. Despite their proximity, the sinkholes differ greatly from each other in terms of abiotic factors. For example, total depth varies between 0.5 and 15 m, Secchi depth lies between 0.25 and 4 m, and salinity between 4 and 120 ppt. Using regression analyses, we found that fish abundance and condition are primarily influenced by biological factors, particularly the presence of other fish species.