Comparison of three burrowing crayfish capture methods based on relationships with species morphology,seasonality, and habitat quality

Three techniques used to capture burrowing crayfish were compared for efficiency and efficacy near Big Oaks National Wildlife Refuge. Excavation of burrows, Norrocky burrowing crayfish trap (NBCT), and burrowing crayfish mist nets (BCN) were simultaneously compared for capture efficiency and trap efficacy. Additional research goals were to evaluate patterns in capture rates with changes in seasonal activity, influence of burrow diameter size to capture success, relationships between differences in morphological characteristics of species and capture success, and capture success and habitat quality. Excavation caught significantly more burrowing crayfish than the other two methods (40.7%), but the NBCT (5.2%) was not significantly different from the BCN (4.5%) in trap efficiency. The relative percent efficacy success adjusted for effort of each method was 2.61% for the NBCT and 2.24% for the BCN. Positive correlations between habitat quality and increasing NBCT (rs = 0.414, P = 0.023) and increasing BCN (rs = 0.447, P = 0.013) trap efficiency success were found, while no significant linear relationship (r s = -0.134, P = 0.479) was observed between the Qualitative Habitat Evaluation Index score for habitat quality and excavation success. No significant correlation was observed between NBCT (rs=-0.273, P = 0.144) or BCN (rs = -0.286, P = 0.125) and annual date; however, a significant linear relationship was observed for excavation (rs = -0.372, P = 0.043) and annual date of collection. Individuals of Cambarus (Tubericambarus) polychromatus and Cambarus (Lacunicambarus) species "A" that were collected were significantly different in size; however, this was not a result of gear bias. A positive correlation was observed between C. polychromatus size and habitat quality indicating longer lived individuals occur in higher quality habitats.