The Reproductive Drain Hypothesis is a long-held and widespread idea that the energetic costs associated with reproduction drive growth deceleration in fish by appropriating energy previously allocated for somatic growth prior to maturity. This theoretical notion remains contentious and has been challenging to test given the difficulty of controlling reproduction in wild populations. In this study, we evaluated the Reproductive Drain Hypothesis by comparing the lifetime growth of sterile (i.e., triploid) walleye (Sander vitreus) with normal, fertile conspecifics co-occurring in the same ecosystem. We found the Lester biphasic growth model, a model developed specifically to incorporate the Reproductive Drain Hypothesis, failed to fit the growth patterns of sterile walleye (model weight = 0.081), and sterile walleyes were not larger than fertile ones. This evidence implies that reproduction may not limit energy available for somatic growth and presents an interesting challenge to this long-held concept. Alternatively, we hypothesize that individuals may increase food intake to meet the elevated energetic demands associated with reproduction, and that inheritance and metabolic theory may explain asymptotic growth in fish better than the Reproductive Drain Hypothesis.
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