Date of Award

12-1994

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Forestry, Wildlife, and Fisheries

Abstract

I conducted three studies during the year of 1993 in order to investigate the ecology of the crayfish Procambarus vioscai in the streams of the Kisatchie National Forest. The first study was designed to determine the factors that effect the microdistribution of this crayfish. A direct and positive relationship between the variation in leaf accumulation and crayfish biomass in a location was observed in the study streams. Laboratory observations of the behavior of the crayfish associated with leaf litter and a regression model for structure volume versus crayfish biomass indicated that exploitation of leaf accumulations by P. vioscai is a function of leaf pack distribution and its effects on crayfish competition.

Habitat use and movement of 20 individual crayfish (n=10 for 24 hr summer periods, n=10 for 16 hr winter periods) were observed with the aid of radio telemetry. Fisher's exact tests, comparing habitat use versus habitat availability for each subject individually, revealed nonrandom habitat use by the crayfish (P=6.5*10"^^-0.3) and that crayfish location was positively influenced by the presence of cover. An ANOVA model indicated that the crayfish was nocturnal and displayed greater activity during the summer than during the winter.

P. vioscai production parameters and life history characteristics were also recorded. Observations supported the hypothesis that this crayfish is a tertiary borrower that spawns in the summer and releases its brood in the fall. Estimates of cohort and annual production (8,184.6 and 3,273.8 kg/ha, respectively), cohort and annual turnover ratio(6.1 and 2.5, respectively), and mean biomass (1,461.0 kg/ha) were made with the size-frequency method and revealed this crayfish to be successful at utilizing its environment. Laboratory data and field observations lead me to believe that this crayfish has a two year seven month length of life and that most of its growth occurs in its first year of life.

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