Validated annual band‐pair periodicity and growth parameters of blue‐spotted maskray Neotrygon kuhlii from south‐east Queensland, Australia

Abstract

Age and growth parameters were derived for blue-spotted maskray Neotrygon kuhlii from Moreton Bay in subtropical eastern Australia. Maximum age estimates of 13 and 10 years were obtained from female (n = 76) and male (n = 44) N. kuhlii, respectively. Estimated ages at maturity for 50% of females and males were 6.32 and 3.95 years, respectively. A three-parameter power function provided the best statistical fit to size at age data in both sexes, providing parameter estimates of y(0) = 163.13, a = 58.52 and b = 0.58 for females and y(0) = 165.13, a = 59.02 and b = 0.54 in males. The two-parameter von Bertalanffy growth function was used to estimate biological parameters based on disc width (W(D)) for both female (W(Dinfinity) = 465.81 mm, K = 0.13 year(-1), b = 0.63) and male N. kuhlii (W(Dinfinity) = 385.19 mm, K = 0.20 year(-1), b = 0.54). Annual band-pair deposition was observed in three calcein-injected N. kuhlii after periods of liberty ranging from 631 to 1081 days. Centrum edge analysis indicated that annual band-pair formation was generally consistent within this population, with translucent bands formed over spring and summer and opaque bands formed in autumn and winter. Individual growth rates obtained from tagged specimens were similar to power function growth predictions. These results support previous characterizations of this common trawl by-catch species as comparatively resilient to non-targeted catches, although higher catch rates outside Australia infer a need for cautious management.

Life-history traits of a small-bodied coastal shark

“…Annual band formation was validated from a flurochrome-labelled shark, recaptured after almost 1 year at liberty, and estimated to be 1.3 years at the time of recapture. Such annual band validation is consistent with reports from other coastal carcharhiniform sharks (Simpfendorfer et al 2002;McAuley et al 2006;Harry et al 2011a) and inshore elasmobranchs (Pierce and Bennett 2009). Annual band formation was further verified across all ages from centrum-edge analysis, with opaque bands forming during the Austral summer.…”

“…This thickness was chosen because it had the highest readability for a trial that comprised 150-mm-, 300-mm-, 450-mm-and 600-mm-thick sections. Two training counts were then performed on all centra (Pierce and Bennett 2009). Because the banding remained indistinct in a large proportion of these, crystal violet staining was used to enhance the banding on the corpus calcareum.…”

“…Centra of a recaptured shark were prepared as described above and the number of band pairs formed distal to the fluorochrome label were counted and compared with time at liberty (Pierce and Bennett 2009). Additionally, centrum-edge analysis (CEA) was conducted to qualitatively verify the timing of band formation by observing the translucency or opacity of the centrum edge (Cailliet and Goldmann 2004).…”

Ontogenetic Shifts in Brain Organization in the Bluespotted Stingray <b><i>Neotrygon kuhlii</i></b> (Chondrichthyes: Dasyatidae)

“…Secondly, we used univariate general linear models (GLM) to assess whether sex, maturity status, or the interaction between them (sex × maturity status) has a significant influence on the scaling of overall brain size, or the size of any of the seven major brain areas. Sex, maturity status, and sex × maturity were considered a priori to be potentially significant because males and females of this species have different overall growth rates (with females growing more slowly) but larger sizes compared to males [Pierce et al, 2009;Pierce and Bennett, 2010]. Females also reach sexual maturity at a later age and a greater size than males [Pierce et al, 2009;Pierce and Bennett, 2010].…”

The biology and ecology of the tiger shark (Galeocerdo cuvier) on the east coast of Australia

“…All sections deemed to be of readability 5 were excluded from further analyses. Two training counts were performed on all centra in the first instance (Pierce and Bennett, 2009;Gutteridge et al, 2013). Ages were then estimated from three independent counts conducted by both the primary author (B. Holmes, Reader 1) and secondary author (V. Peddemors,…”