Andrew R. Munro

Development and Evaluation of Methods for Osmotic Induction Marking of Golden Perch Macquaria ambigua with Calcein and Alizarin Red S

Abstract We conducted a series of osmotic induction procedures for marking golden perch Macquaria ambigua with calcein and alizarin red S (ARS), evaluated the factors that influenced mark quality, and tested for any effects on fish growth and mortality. Three aspects of the marking protocols were considered: immersion time in a 5% salt solution (0, 5, or 10 min), immersion time in the fluorescent dye (5 or 10 min), and concentration of the dye (low or high). Quantitative estimates of mark intensity using photographs of marked fish were made with image analysis software. Although there were some significant interactions between factors, salt immersion was generally the primary determinant of mark intensity, followed by dye concentration and dye immersion time. Fish marked with calcein did not have higher mortality rates than unmarked fish and had significantly higher growth rates. The highest-exposure ARS treatments resulted in higher mortality and lower growth rates than for unmarked fish. Following this ...

Transgenerational marking of freshwater fishes with enriched stable isotopes: a tool for fisheries management and research

A promising new method of marking larval freshwater fishes with enriched stable isotopes by means of injecting the maternal parent with the marking agent was investigated. The (138)Ba:(137)Ba ratios in the otoliths of larval golden perch Macquaria ambigua were compared to determine the effect of injecting female broodstock with different dosages of enriched (137)Ba at various times before spawning. There was 100% mark success in the progeny of fish injected with 20 microg g(-1) of enriched (137)Ba 24 h before inducing spawning with hormones and 40 microg g(-1) administered at the same time as inducement of spawning. Injection of 40 microg g(-1) enriched (137)Ba 21 days before spawning resulted in only 81% mark success and suggests rapid elimination of barium in M. ambigua. Injection with enriched (137)Ba did not significantly affect the fertilization rate, number of fertilized eggs or hatching rate compared with long-term hatchery records. These results suggest that transgenerational marking is an effective and affordable means of mass-marking larval fishes. Thousands of larval fishes can be permanently marked with a unique artificial isotopic mark via a single injection into the maternal parent, thus avoiding the handling of individual fishes or having to deal with chemical baths. Because no single mark or tagging method is suitable for all situations, transgenerational marking with enriched stable isotopes provides another method for researchers and managers to discriminate both hatchery-reared and wild fishes.

Production of External Fluorescent Marks on Golden Perch Fingerlings through Osmotic Induction Marking with Alizarin Red S

Abstract Osmotic induction marking trials with alizarin red S (ARS) were conducted on golden perch Macquaria ambigua to evaluate the use of ARS as a lower-cost alternative to osmotic induction marking with calcein for producing external fluorescent marks on hatchery-produced fish. After a 10-min immersion in a 5% solution of salt, experimental groups of golden perch were rinsed for 5 s in freshwater and immersed for 10 min in either a 0.1% or 0.5% solution of ARS, whereas control groups were either left untreated or immersed in a 0.1% solution of ARS for 10 min without prior immersion in the salt solution. All fish treated in the 0.5% solution of ARS died within 5 min of immersion, but no mortalities were observed in any of the controls or fish treated with the 0.1% solution of ARS. External fluorescent marks were observed on both the osmotic induction-marked fish and the direct ARS immersion-marked fish 100 d after treatment, but the osmotic induction-marked fish possessed more intense marks. Clear marks...

Determining Mark Success of 15 Combinations of Enriched Stable Isotopes for the Batch Marking of Larval Otoliths

Abstract Chemical marking of otoliths via immersion in solutions of enriched stable isotopes provides a means of distinctively marking large batches of hatchery-produced fish. Four enriched stable isotopes (barium: 137Ba and 138Ba; strontium: 88Sr; magnesium: 24Mg) were used individually and in combination to determine mark success and the ability to correctly classify 15 unique batch marks in the otoliths of larval Murray cod Maccullochella peelii. Marking with the enriched stable isotopes 137Ba, 138Ba, and 88Sr (individually or in combination) produced clear and distinctive marks (98% mark success) with 93% of fish correctly classified to their respective isotope mark. Despite exposure of the fish to an altered Mg isotope ratio in the water, a corresponding shift in the otoliths was not observed (8% mark success), and many 24Mg-enriched fish were misclassified. Due to the low cost and minimal effects on hatchery protocols, the use of Sr and Ba isotopes to mark hatchery-reared fish at the larval stage ha...

Contribution of stocked fish to riverine populations of golden perch (Macquaria ambigua) in the Murray–Darling Basin, Australia

Stocking of native fishes is conducted to augment riverine fisheries in many parts of the world, yet most stocking activities are conducted without empirical information on their effectiveness or impacts. In the Murray–Darling Basin (MDB), Australia, stocking has been underway for several decades to maintain recreational fisheries. We stocked chemically tagged golden perch (Macquaria ambigua) fingerlings in three rivers to determine the proportions of stocked fish within populations of the species. Stocked sites were monitored for up to 5 years in the Murrumbidgee River, Edward River and Billabong Creek and non-stocked sites were monitored in the Murray River. Catch per unit effort of stocked year classes increased substantially in Billabong Creek, with stocked fish contributing 100 (2005), 79 (2006) and 92% (2007). Chemically tagged fish comprised 18–38% of the respective age classes in the Murrumbidgee and Edward rivers and there was little evidence of natural recruitment in the non-stocked Murray River. Tagged fish generally attained the legal minimum size within 4 years and had dispersed up to 60km from the original release location. Our results demonstrate that artificial stocking has the potential to strongly influence the abundance and population structure of golden perch in rivers of the MDB.