Genetic diversity and restricted genetic connectivity in an endangered marine fish (

Determining the genetic diversity and differentiation among populations is a critical element of conservation biology, but for many aquatic, data-deficient species with small population sizes, this not possible. Closely related may therefore provide model. For first time, using over 4000 single-nucleotide polymorphism loci, we characterise structure one world’s rarest marine fish, spotted handfish (Brachionichthys hirsutus), which also member most threatened bony fish family (Brachionichthyidae). Fin clips were taken from 170 live across seven disjunct sites within only known estuary (in Tasmania, Australia) where multiple are found. Spatially discrete clustered into three groupings significant variance in allele frequencies (overall FST = 0.043), even at scale estuary, was observed. Furthermore, low contemporary migration rate estimates suggest homogeneity between locations. Because connectivity, clusters should be considered as separate management units. This insight strategies other family.