Nursery sources and cohort strength of young‐of‐the‐year common carp (Cyprinus carpio) under differing flow regimes in a regulated floodplain river

Abstract

Otolith chemistry and standardised catch data were used to identify key nursery sources for common carp (Cyprinus carpio) in the mid-Murray River region, south-east Australia, and to quantify annual young-of-theyear (YOY) cohort strength under varying hydrological conditions across 4 years (2005/2006-2008/2009). Analysis of trace element concentrations (i.e., Mg:Ca, Mn:Ca, Sr:Ca, Ba:Ca) near the otolith core of post-larval carp (< 1 month of age) resulted in moderate to very high spatial discrimination of nursery sources within years. Otolith elemental concentrations were not stable across years at all nurseries, necessitating resampling of post-larvae each spawning season to characterise nursery sources. Annual electrofishing surveys detected a strong cohort of YOY carp (4-6 months of age) in 2006, following a period of natural and artificially augmented high flows in the Murray River main channel and tributaries and extended floodplain inundation in the Barmah-Millewa Forest (BMF). Few YOY were captured in 2007, 2008 or 2009years characterised by low flow conditions in the region and no floodplain inundation in BMF. Maximum likelihood estimation of nursery origins indicated that the BMF was the primary source for YOY fish captured from main channel (Torrumbarry Weir) and tributary (lower Goulburn River) sites in 2006, with the lower Goulburn River making a smaller contribution to the YOY cohort. These results demonstrate the importance of hydrology in determining spatial and temporal patterns of carp recruitment in regulated rivers and highlight the need to consider such factors when attempting to optimise ecological outcomes from environmental flow delivery.

Strong population structure deduced from genetics, otolith chemistry and parasite abundances explains vulnerability to localized fishery collapse in a large Sciaenid fish, Protonibea diacanthus

“…Rather, the misclassification of individuals to distant locations appears to be due to the high number of locations relative to the limited number of elements that contributed to location separation in the discriminant function analysis. Similar overlap and misclassification in otolith chemical signatures among locations have been reported previously both in freshwater (e.g.,Macdonald & Crook, 2014) and marine (e.g.,Miller, Banks, Gomez-Uchida, & Shanks, 2005) studies.…”

Listening with the invasive fish ear: applications and innovations of otolith chemistry analysis in invasive fish biology

“…Subsequently, the existence of inter-annual variability in chemical signatures associated with specific nursery grounds was identified, showing that precise determination of production hotspots-either based on capture sites or habitat types-was plausible following the formulation of an annual baseline database of location-specific chemical signatures (Macdonald et al 2010;Crook et al 2013). Ultimately, Macdonald and Crook (2014) demonstrated that the use of an annual baseline database provided a significant improvement of classification power of post-larvae origin to their nurseries (53 to 70% of correct classification). Admittedly, the classification procedure was not without error but could provide data sufficiently precise for management applications (e.g.…”

Age determination in common carp Cyprinus carpio: history, relative utility of ageing structures, precision and accuracy

“…Vilizzi and Walker 1995). Thus, studies have used either the 'larger' asterisci (Crook and Gillanders 2006;Blair 2008;Li et al 2011;Blair and Hicks 2012) or the lapilli (Macdonald et al 2010;Crook et al 2013;Macdonald and Crook 2014), even though remarkable differences in microchemistry have been observed between the two pairs, suggesting the need for their concomitant employment (Macdonald et al 2012).…”