Using occupancy and species distribution models to assess the conservation status and habitat use of the goldline darter <i>(<scp>P</scp>ercina aurolineata</i>) in Georgia, <scp>USA</scp>

Abstract

Abstract The goldline darter ( P ercina aurolineata ) is threatened by recent increases in urbanisation in the C oosawattee River watershed, but no studies have addressed their current status. Similarly, limited data on habitat use make it difficult to understand factors that may impact this species. We compared occurrence data before (1996–2000) and after (2009–2011) a period of rapid development and population growth within the watershed. Single‐season occupancy models were built to account for imperfect species detection and to identify habitat covariates. M ax E nt was used to identify important stream reaches for conservation and to understand landscape scale factors correlated with the distribution of goldline darters. Our results indicate a high proportion of sites occupied upstream of Carters Lake during the historic and recent time periods, with no evidence of decline. However, occurrences of goldline darters for sites in T alking R ock C reek and the lower C oosawattee R iver were sparse in the historic period and absent during the recent period. The probability of detecting goldline darters is low and was positively associated with the occurrence of small substrate. Species distribution models were strongly influenced by watershed area and elevation and indicated a high probability of suitable habitat within the C oosawattee R iver and large tributaries upstream of C arters L ake. While goldline darter occupancy is currently stable upstream of C arters L ake, continued urbanisation is a threat to long‐term persistence. We recommend additional monitoring and describe a protocol that allows for precise estimates of species occupancy while minimising the risk of sampling‐related mortality.