Oral Presentation Australian Society of Fish Biology and Oceania Chondrichthyan Society Conference 2016

Integrative approach to elucidating the population structure of coastal reef fish in northern Australia (Part I: Otolith chemistry) (#59)

Jonathan A Taylor , Di P Barton 1 2 , Laura Taillebois 2 , David Crook 2 , Thor Saunders 1 , Alan Grieg 1 , Mark Hearnden 1 , David J Welch 3 , Stephen J Newman 4
  1. Fisheries Research, Northern Territory Government Department of Primary Industry and Fisheries, Darwin, Northern Territory, Australia
  2. Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, Northern Territory, Australia
  3. C2O Fisheries, Cairns, Queensland, Australia
  4. Western Australian Fisheries and Marine Research Laboratories, Department of Fisheries, Government of Western Australia, Perth, Western Australia, Australia

Information on the structure of exploited fish populations is critical to their sustainable harvest, allowing appropriate management regimes to be implemented at spatial scales that reflect the population dynamics of a species across it range. This project utilised microsatellite DNA, parasitology and otolith microchemistry techniques to examine population structure among populations of three coastal reef fish species across northern Australia (Protonibea diacanthus, Lutjanus johnii and Lethrinus laticaudis).

Part I of the project involved using otolith microchemistry to examine population structuring of these three species of coastal reef fish. By analysing variation in multi-elemental otolith chemical signatures, it is possible to estimate the levels of connectivity and population structure between fish sampled from different areas. Additionally, the persistence of these patterns was investigated by sampling three specific areas of each otolith that represented a different life history stage of the fish: the core, or “primordium”, reflecting the larval phase; the near-core, representing the early juvenile phase; and the otolith margin to represent the sub adult/adult phase. Analysis of the multi-elemental otolith chemistry signatures using linear discriminant function analysis (LDFA) and multi-variate analysis of variance (MANOVA) showed that variability in otolith chemistry was sufficient to discriminate fish collected from sites separated by distances of 50-1200km.

Population structure is influenced by behavioural and physical processes that act over a range of temporal scales. Therefore, the use of multiple and potentially complementary techniques that integrate information over different scales is likely to provide the best inference on population structure of fish. Incorporating the results from the otolith microchemistry research with the genetic and parasitology results, which have different spatial and temporal resolution, allows more precise estimation of both the spatial and temporal scale of stock structuring that exists for these three commercial and recreationally important fish species across northern Australia.