Abstract
Understanding long-term changes in life-history traits is central to assessing and managing freshwater fisheries. In this study, we explored how life-history traits have shifted in association with long-term change in population status for a native fish species (freshwater sleeper, Odontobutis sinensis, a by-catch species of shrimp traps) in the middle Yangtze lakes, China. We assessed the life-history traits of the species from Honghu Lake in 2016, where abundance had been dramatically lower following about 60 years of high fishing pressure, and made comparisons to similar data from Liangzi Lake (1957), when fishing intensity was low and abundance was high, and Bao’an Lake (1993–1994), when about 10 years of intense exploitation had occurred and abundance had greatly declined. Modern Honghu Lake sleeper exhibit life-history traits that are substantially more opportunistic compared to both of the historical populations. Modern fish were larger at age-1 and had significantly faster growth rates, a higher prevalence of sexually mature individuals and increased fecundities. Fish from the historical samples were larger and had higher age class diversity and delayed sexual maturation. Combined, the data suggest that faster growth towards early sexual maturation and reduced body sizes are associated with destabilized populations and ecosystems. Similar life-history patterns are common in other declined fish populations under exploitation. Recovering historic fish life-history dynamics requires conservation management policies aimed at reducing harvest and improving floodplain habitats.
Highlights
Introduction iationsLife-history traits are a fundamental outcome of evolutionary processes [1,2,3]
How thethe life-history of the sleeper became inincreasingly opportunistic in connection with population decline over multiple decades creasingly opportunistic in connection with population decline over multiple decades in in the Yangtze Lakes, China
The sleeper is a nesting species in which the males guard the Yangtze Lakes, China
Summary
Life-history traits are a fundamental outcome of evolutionary processes [1,2,3]. Life-history traits vary widely on an interspecific basis over space and time, which has implications for conservation management [4,5]. Several theoretical frameworks have emerged for understanding the life-history strategies of species in response to environmental conditions [6,7,8]. The r/K selection theory continues to be one of the most widely recognized frameworks, but it receives frequent challenges [9,10]. Winemiller and Rose (1992) proposed a semi-triangular surface model upon which the life-history of any fish species or population rests.
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