Climbing up the ladder: male reproductive behaviour changes with age in a long-lived fish

Abstract

High reproductive performance is the key attribute of male fitness, especially due to the high reproductive skew among the males of most animal species. Males of long-lived iteroparous species have opportunities to improve upon their previous reproductive attempts with increasing age. We collected individual-specific reproductive behaviour and age data on a cyprinid fish, the asp (Leuciscus aspius), from 2015 to 2019. We tested whether males changed their performance over time using a unique dataset where individual performance was recorded yearly with passive telemetry. Individual fish behaviour was tracked from one to five reproductive seasons at least a year after the tagging. Fish were scored by measures of quality (first arrival time, number of visits and time spent in the reproductive grounds, and encountered proportion of males to all adult fish). In general, fish improved in the first three metrics with age, suggesting a shift towards behaviours likely to enhance reproductive success as individuals aged. A larger size at tagging was predictive of earlier fish arrival on the spawning ground in subsequent years. Our study therefore demonstrates the importance of age as a factor when considering the potential reproductive success of long-lived fish species. Significance statement High reproductive performance is the key attribute of male fitness. Males of long-lived species reproducing multiple times in their life have opportunities to improve upon their previous reproductive performance with increasing age. In this 5-year study, we tracked a large cyprinid fish with telemetry systems during their reproduction. We investigated the age-related behavioural changes in males and demonstrated the improvement of male reproductive timing and length of stay with potential repercussions for male’s reproductive output. We emphasize the importance of old and experienced individuals among the fish population, which are often targeted and selectively removed from the human-managed waters.

Disentangling the effects of male age and mating history: Contrasting effects of mating history on precopulatory mating behavior and paternity success

“…In agreement with this prediction, after controlling for mating history, we found that older male mosquitofish spent significantly more time chasing females and trying to copulate. Broadly similar findings have been reported in other taxa where older males are more persistent in the mating attempts and/or more successful at inseminating females (Jones et al 2007;Fischer et al 2008;Pérez-Staples et al 2010;Somashekar and Krishna 2011;Karl and Fischer 2013;Ekanayake et al 2017;Rodríguez-Muñoz et al 2019;Okada et al 2020;Šmejkal et al 2021), although some studies also report that older males show a decline in courtship and mating attempts (Fricke and Maklakov 2007;Prokop et al 2007;Dean et al 2010;Kanuga et al 2011;Ruhmann et al 2018;Churchill et al 2019;Lai et al 2020). This general trend for old males to invest more in sexual signaling has been further supported by a recent meta-analysis (Dougherty 2021).…”

“…2020; Šmejkal et al. 2021), although some studies also report that older males show a decline in courtship and mating attempts (Fricke and Maklakov 2007; Prokop et al. 2007; Dean et al.…”

Does Fish Conditioning in Aquaculture Increase Survival Success in the Wild? A Case Study on a Cyprinid Fish

“…Asp inhabits primarily fluvial environments and, to a lesser extent, lacustrine environments. They can thrive in the lacustrine environment provided that it is connected to a riverine system to ensure successful reproduction [48,49]. This species is protected in selected areas of the European Union under the Habitats Directive, and in some protected areas included in the NATURA 2000, the population is maintained by capturing adult fish and artificially spawning and rearing them to the stocking size [50].…”

“…The study site has the largest population of asp in the country and is protected by Natura 2000 [7]. The shoreline of Želivka Reservoir was sampled with an electrofishing boat (electrofisher EL 65 II GL DC, Hans Grassel, Schönau am Königsee, Germany, 13 kW, used voltage and current 500 V, 10 A, pulsed DC, frequency 70 × s −1 ) in 24-26 August 2020, on 18 March to 25 April 2021 during the spring spawning migration of asp [48] and on 25-27 August 2021 (Figure 2). The boat has approximately a six-meter-wide and a three-meter-deep energized field.…”

“…Paralyzed individuals were placed in the aerated vat and when the fish sampling was completed at a specific location, asp were immediately scanned for potential PIT tags, measured and released back into the reservoir after recovery. During the 2021 spring season (18 March to 6 May), three antenna arrays (antenna loop size 10-18 × 0.6 m, LF HDX RFID readers) were installed in the tributary as an additional tool to detect surviving fish aside from electrofishing (details in [48]) and the PIT tag detections were used as a sign of fish survival.…”