Get access

An assessment of otoliths, dorsal spines and scales to age the long-finned gurnard, Lepidotrigla argus, Ogilby, 1910 (Family: Triglidae)

Authors

  • D. E. van der Meulen,

    Corresponding author
    1. NSW Department of Primary Industries, Cronulla Fisheries Research Centre of Excellence, Cronulla, NSW, Australia
    2. School of Biological Sciences, University of Wollongong, Wollongong, NSW, Australia
    • NSW Department of Primary Industries, Batemans Bay Fisheries Centre, Batemans Bay, NSW, Australia
    Search for more papers by this author
  • R. J. West,

    1. School of Biological Sciences, University of Wollongong, Wollongong, NSW, Australia
    Search for more papers by this author
  • C. A. Gray

    1. NSW Department of Primary Industries, Cronulla Fisheries Research Centre of Excellence, Cronulla, NSW, Australia
    Search for more papers by this author

Author's address: Dylan E. van der Meulen, NSW Department of Primary Industries, Batemans Bay Fisheries Centre, PO Box 17, Batemans Bay, NSW 2536, Australia.

E-mail: dylan.van.der.meulen@dpi.nsw.gov.au

Summary

Sagittal otoliths, dorsal spines and scales were critically assessed as structures to potentially determine the age of the long-finned gurnard, Lepidotrigla argus. Counts were made of opaque growth increments and a readability score was assigned to each structure. Comparisons of growth increment counts were made between structures and between readings. All three structures showed some degree of readability and quantifiable growth increments, but this varied within fishes and between structures. Initial results showed that whole otoliths were more suitable to determine age estimates than dorsal spines and scales. Scales were considered unsuitable due to between reading ageing bias, variation in age estimates between structures, low precision and poor readability for this species. Dorsal spines showed evidence of loss of growth increments due to hollowing of the vascular core, which resulted in underestimation of older individuals in comparison to whole otoliths. Further analysis showed that growth increment counts from whole otoliths were lower for older individuals in comparison to sectioned otoliths. It is suggested that this is because of decreased clarity of growth increments towards the outer margin of whole otoliths in older individuals; this problem was not present with sectioned otoliths. It was concluded that sectioned otoliths were a more suitable structure from which to estimate age of L. argus than were whole otoliths, dorsal spines and/or scales.

Ancillary