ABUNDANCE OF LAMPREY LARVAE AND PHYSICAL HABITAT

Southern brook lamprey larvae, Ichthyomyzon gagei, were collected from four creeks in Alabama and Mississippi. Larvae abundance (number m-2) and length (mm) were measured over a range of sites to quantify some of the physical parameters involved in larval habitat selection. Particle size distribution, hydraulic conductivity, porosity and organic content were the factors analyzed. Abundance of larvae was greatest when particles smaller than 0.15 mm and 1.0-2.0 mm in diameter represented at least 40% and 8% dry weight of the substrate, respectively. Abundance of larvae was lowest when the small particles represented less than 10% dry weight of the substrate. A strong inverse relationship was observed between density and length of larvae. All other parameters did not significantly affect lamprey habitat selection. Results of this study may be applicable in directing attempts at aquatic habitat restoration for lamprey in endangered streams.