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 statementHigh 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.
Highlights
Animals acquire experience during their lifetime, which provides them with an important baseline for their decisions and behavioural changes through ontogeny
The average first arrival time of the females, which was needed for protandry computation, was based on the 51, 98, 228, 327 and 438 previously tagged females that arrived in reproductive seasons 2015 to 2019, respectively
Data obtained from telemetry tracking of male asp over five annual spawning seasons showed that males improved their performance with respect to three out of four reproductive traits as they aged: earlier arrival to spawning grounds, longer time spent and number of visits to the spawning ground
Summary
Animals acquire experience during their lifetime, which provides them with an important baseline for their decisions and behavioural changes through ontogeny The onset of reproductive ability and choice of successful reproductive strategy are crucial decisions affecting animal fitness. The possibility of reproducing multiple times in a lifetime, known as iteroparity, provides individuals with the chance to improve on their reproductive readiness (i.e. ability to gain early matings), as well as the potential to learn more efficient mating strategies (i.e. ability to achieve more matings within a given reproductive season; Becker et al 2008; Arnaud et al 2013). Low initial reproductive success in the first reproductive season may be compensated for by relatively higher reproductive success later in life (Bowen et al 2006; Limmer and Becker 2010; Arnaud et al 2013).
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