Biological characteristics of the primitive flatfish Indian halibut (Psettodes erumei) from the tropical northeastern Indian Ocean, including implications of the use of incorrect aging methods on mortality estimates

Abstract

The Indian halibut (Psettodes erumei) is an important flatfish species in tropical and subtropical waters of the northern Indian Ocean. However, inappropriate aging methods used in previous studies of Indian halibut limited the use of age and growth data from those studies. This study highlights the importance of correct aging methods and identification of sexually dimorphic growth, particularly if growth characteristics are used to estimate mortality rates. Counts of opaque zones in whole otoliths of Indian halibut were almost always fewer than those in their corresponding sections, particularly for older individuals. Multiple validation methods have been used to demonstrate that opaque zones form annually in otoliths of Indian halibut. Although the frequency of females increased with size, because of sexually dimorphic growth, males attained a greater maximum age (16 versus 11 years). Because of the greater ages and rapid early growth of Indian halibut described in this study, natural mortality estimates calculated by using the Pauly equation, particularly for males, were higher than estimates derived from the same equation in previous studies, which employed growth parameter estimates based on ages derived from whole otoliths, vertebrae, or monthly length-frequency trends and, typically, did not account for sexually dimorphic growth. In northwestern Australia, spawning in Indian halibut commences when water temperature and day length begin to increase and occurs between early spring and late summer.

Estimating fish mortality rates from catch curves: A plea for the abandonment of Ricker (1975)'s linear regression method

“…Given the different analytical shortcomings of the LR method, the CR and CRCB methods have sometimes been preferred to estimate mortality rates (e.g., Clark et al, 2023;Coulson & Poad, 2021) if not the WLR method instead (e.g., Jefferson et al, 2021;Sullivan et al, 2020).…”

“…Given the different analytical shortcomings of the LR method, the CR and CRCB methods have sometimes been preferred to estimate mortality rates (e.g., Clark et al ., 2023; Coulson & Poad, 2021) if not the WLR method instead (e.g., Jefferson et al ., 2021; Sullivan et al ., 2020). Although the CRCB method constitutes an improvement over its original version (Smith et al ., 2012), it nonetheless requires that Z and its SE must be approximated from S as obtained from the original method to then apply correction factors (Hoenig et al ., 1983; Smith et al ., 2012).…”

Insights into the Mitochondrial Genetic Makeup and Miocene Colonization of Primitive Flatfishes (Pleuronectiformes: Psettodidae) in the East Atlantic and Indo-West Pacific Ocean

“…[9]. Furthermore, the extraordinary transformation from bilateral pelagic larval symmetry to adult flattened symmetry limits flatfishes to demersal zones on the sea bottom, owing to their unusual temperature-mediated spawning behavior [10]. While most flatfish species have either a right-sided (dextral) or a left-sided (sinistral) mouth, several species, including Psettodes, display varying degrees of dextral to sinistral polymorphism [11].…”

Aseasonal and short life cycles of the protandrous hermaphrodite blue threadfin (Eleutheronema tetradactylum) in a near-equatorial tropical region

“…Some studies on other fish species have reported differences in reproductive characteristics between low-and high-latitude habitats (e.g. Gray et al 2012;Wakefield et al 2015;Coulson and Poad 2021). Hence, there is a need to investigate the life history, including reproductive season, of E. tetradactylum beyond Australia, especially in near-equatorial tropical habitats.…”