Using otoliths to estimate age and growth of a large Australian endemic monocanthid, Nelusetta ayraudi (Quoy and Gaimard, 1824)

Abstract

Nelusetta ayraudi (the ocean leatherjacket) is an endemic Australian monacanthid species distributed from North West Cape (Western Australia) south to southern Queensland. The commercial and recreational fisheries targeting Nelusetta ayraudi have expanded substantially along the coast of New South Wales (NSW) in recent years but there exists little biological information on which to base effective management of this growing fishery. World-wide, only a few studies have aged monacanthids. Of these, researchers have interpreted periodic increments in bony structures such as vertebrae and anterior dorsal spines in preference to those found in otoliths. In this study we estimated age of N. ayraudi by counting growth increments in sectioned otoliths. The periodicity of increment formation was validated using a vital stain, (oxy-tetracycline), injected into young-of-theyear fish. Growth was rapid especially as juveniles with N. ayraudi attaining approximately 220 mm after 1 year and 340 mm after 2 years. No differences in growth rates were detected between sexes or between fish captured at different latitudes (zones). The largest male (605 mm, Total Length-TL) and female (656 mm, TL) were both recorded from northern NSW, with both sexes attaining the maximum age of 6+ years from northern and southern NSW. The von Bertalanffy parameters describing growth for N. ayraudi were L 1 =591 mm (TL), k=0.377 year −1 and t o =−0.247 years.

Life‐history traits of the leatherjacket Meuschenia scaber, a long‐lived monacanthid

“…In conclusion, this research describes the life‐history traits of a common monacanthid species in Australasian waters, M. scaber . The life‐history parameter estimates presented here indicate small differences between the sexes in growth, but substantial differences in lifespan and mortality, as seen in other species of the same family (Miller et al., ). More importantly, M. scaber is the longest‐living monachantid species described so far and possibly the oldest documented for the entire suborder.…”

“…Miller et al . () reviewed reported longevity for species of the family Monacanthidae and found a maximum recorded age of 9 years, attained by both N. ayraud and Thamnaconus septentrionalis (Günther 1874). Although the maximum age of M. scaber males recorded in this study is consistent with the lifespan reported for other monacanthids, females are clearly longer lived.…”

“…Otolith‐based studies have also been successfully conducted on early life stages and juveniles of S. hispidus (Rogers et al., ), Rudarius ercodes (Jordan & Fowler 1902) and Paramonacanthus japonicus (Tilesius 1809) (Kawase & Nakazono, ) and Monacanthus tuckeri (Bean 1906) (Ben‐David & Kritzer, ). Annual increment deposition has been reported in sagittal otoliths of the monacanthid species Meuschenia australis (Donovan 1824) , Penicipelta vittiger (Castelnau 1873) and N. ayraud (Barrett, ; Miller et al., ), suggesting that this pattern occurs generally in the group.…”

“…Miller et al . () recently reviewed otolith‐based age estimation for N. ayraud and emphasized however, the limited precision and accuracy of previous results based on age estimation using vertebrae. Otolith‐based studies have also been successfully conducted on early life stages and juveniles of S. hispidus (Rogers et al., ), Rudarius ercodes (Jordan & Fowler 1902) and Paramonacanthus japonicus (Tilesius 1809) (Kawase & Nakazono, ) and Monacanthus tuckeri (Bean 1906) (Ben‐David & Kritzer, ).…”

Coastal Fish Assemblages Reflect Geological and Oceanographic Gradients Within An Australian Zootone

“…Despite their ubiquitous presence on reefs, and their conspicuous nature, there is little knowledge of the biology and demography of monacanthids [ 48 ]. Some are known to have very small home ranges on reefs [ 50 ], whilst the largest, endemic species Nelusetta ayraudi forms the basis of a significant fishery in sub-tropical and temperate shelf waters [ 51 ]. The labrids of temperate reefs are much better known for their hermaphroditism and social organisation [ 49 ], territoriality or small home ranges on reefs [ 52 ], niche partitioning [ 53 ] and plasticity in diet [ 54 ].…”