Precision and accuracy of age estimates in Cyprinus carpio var. communis linnaeus, 1758, and schizopyge niger (Heckel, 1838) using hard anatomical parts

Abstract

The study of fish age and growth is a fundamental technique that is significant not only for fisheries biology but also for stock management and productivity. To investigate population dynamics and maintain sustainable yields in aquaculture, it is necessary to have detailed knowledge about the age and growth of the fish (Campana and Thorrold, 2001). One of the most crucial tasks for fisheries professionals has remained to be determining the age and growth of the fish (Jackson, 2007). Various ageing structures have reportedly been used for age estimation comparison to determine the most precise and appropriate structure for a fish population (Maceina and Sammons, 2006; Reid, 2007; Phelps et al., 2007). Some of the earliest works on age determination of fishes in India are those of Rao (1935) on Psettodes erumei, Hora and Nair (1940) on Hilsa ilisha, Devnesan (1943) and Hornell and Nayudu (1924) on Sardinella longiceps and Chacko et al. (1948) on Hilsa ilisha. However, because researchers didn't fully understand how often rings form in the body parts of the fish they were studying, they made different guesses about the ages of those species, which have now been shown to be incorrect. Annuli were first observed in the mackerel at Calicut in the early years, but for unknown reasons, the results afterwards seem to have been abandoned. Both Jones and Menon (1951) and Chidambaram and Krishnamurthy (1951) were unsuccessful in locating useful rings in hilsa scales or mackerel otoliths. In the later years, ageing structures were used in the published literature on Indian freshwater fishes to connect age with growth rather than evaluate the accuracy of age estimates (Johal et al., 1983; Johal and Tandon, 1985; Johal and Tandon, 1992; Dua and Kumar, 2006). In the past five years, advances in ageing methodology and regional studies have deepened our understanding of Kashmir's freshwater cyprinids. Raina et al. (2020) applied high-resolution digital imaging of opercular bones to resolve ambiguous annuli in Himalayan carp, achieving an average percent error below 1.2%. Sharma and Qadri (2021) demonstrated that otolith microstructure combined with stable-isotope analysis can refine age estimates under variable thermal regimes. More recently, Khan et al. (2023) validated opercular ageing against bomb-radiocarbon dating in snow trout (Schizothorax spp.), confirming annual ring deposition even under extreme seasonal fluctuations. The fishes chosen for the current study, Cyprinus carpio var. communis and Schizopyge niger, have diverse structures (opercular bone, scales, dorsal fin ray, and otolith) that can be compared to determine their age. However, no such report which shows the precision and accuracy of age determination in these fishes has been published.