Using enriched stable isotopes of barium and magnesium to batch mark otoliths of larval golden perch (Macquaria ambigua, Richardson)

Abstract

Enriched stable isotope immersion techniques were used to mark the otoliths of larval golden perch (Macquaria ambigua) immediately post-hatch. Two experiments were undertaken: the first involved rearing larvae in water enriched with three concentrations of 137 Ba for 1-5 days. Marks were produced in as little as 1 day; however, otolith isotope ratios reached equilibrium with the water in 5 days at 90 lgAEl )1 . The second experiment involved rearing larvae in isotope enriched water with combinations of stable isotopes of Ba and Mg for 4 days after hatching. Seven significantly different isotopic signatures were produced using three Ba isotopes, which were reflective of the water. Only slight differences were found in otoliths of larvae that were reared in combinations of Mg isotopes, which did not reflect the water chemistry. The length of golden perch at 3 weeks of age showed that isotope immersion did not negatively affect early growth.

Stable isotope marking of otoliths during vaccination: a novel method for mass-marking fish

“…The mark success rate for Mg observed in this experiment is lower compared to that of Woodcock et al (2011a), who tagged golden perch Macquaria ambigua with 26 Mg and achieved approximately 60% mark success using a larval immersion technique. Mg appears to be self-regulated in salmonids and may be sourced from either food or water (Shearer & Åsgård 1992).…”

“…Marking with enriched stable isotopes of magnesium (Mg) has shown poor mark success via immersion and dietary uptake (Woodcock et al 2011a(Woodcock et al , 2012. However, the incorporation of Mg-enriched stable isotopes via direct injection has yet to be investigated and may provide a more successful marking application for Mg isotopes.…”

“…(1) maternal transfer, where enriched stable isotopes injected into brood stock is passed on to the offspring (Thorrold et al 2006, HuelgaSuarez et al 2012; (2) immersion of larvae or juveniles in an isotope-enriched solution (Smith & Whitledge 2011, Woodcock et al 2011a; or (3) delivery via isotope-enriched feeds (Woodcock et al 2013). Marking with enriched stable isotopes of magnesium (Mg) has shown poor mark success via immersion and dietary uptake (Woodcock et al 2011a(Woodcock et al , 2012.…”

“…Current isotope marking techniques indicate that the delivery method, duration of exposure, and the amount of isotope received influence the uptake of enriched isotopes, and consequently, mark success , Williamson et al 2009b, Woodcock et al 2011a). In addition to validating a stable isotope mark delivery method, knowledge of the natural variability in isotopic ratios for a given species and study system is required before a stable isotope fingerprinting method can be considered to be an effective and accurate individual-or mass-marking tool.…”

“…Artificial stable isotope 'fingerprint' marks can be created when enough enriched isotope is introduced to significantly change the relative isotopic abundance in the otolith compared to the natural background isotope ratio. Stable isotopes have been used to successfully mark fish embryos (Thorrold et al 2006, Williamson et al 2009b, larvae (Woodcock et al 2011a), and juveniles (Munro et al 2008, Smith & Whitledge 2011 by changing the isotopic ratios of barium (Ba) and strontium (Sr) in their otoliths. Stable isotopes of Ba and Sr occur naturally in aquatic ecosystems and are detectable in wild fish in ratios that are largely invariant (see reviews by Campana 2005, Gillanders 2005.…”