The conventional view of spawning in iteroparous bony fish, i.e., the “reproductive drain hypothesis,” is based on the observation that somatic growth (in length) slows down noticeably at approximately the time fish attain maturity, and hence the assumption is made that investment in gonadal development slows down growth. However, when this is translated as growth in weight, the weight at first maturity (or puberty) is usually smaller than the weight at which growth rate is highest, i.e., weight growth accelerates after first maturity. We solve this conundrum, with some emphasis on female cod (Gadus morhua), by proposing the hypothesis that the substantial loss of body mass experienced by fish as a result of spawning is quickly compensated for by increased somatic growth after the spawning period, notably because of the increase in food conversion efficiency resulting from a sudden loss of body weight, which necessarily leads to a large increase in relative oxygen supply via the gills. This is consistent with the argument developed elsewhere that declining relative oxygen supply by the gills, whose surface area cannot keep up with increasing body weight, is the reason for growth rate declining with weight in adult fish.

间生硬骨鱼产卵的传统观点，即“生殖流失假说”，是基于这样的观察：大约在鱼达到成熟时，体细胞生长（长度）明显减慢，因此假设投资性腺发育减慢生长。然而，当将其转化为体重增长时，初成熟期(或青春期)时的体重通常小于生长速率最高时的体重，即，初成熟期后体重增长加速。我们解决了这个难题，重点关注雌性鳕鱼（Gadus morhua），提出了这样的假设：鱼类因产卵而经历的体重大幅损失很快就会被产卵期后体细胞生长的增加所补偿，特别是因为体重突然减轻导致食物转化效率增加，这必然导致通过鳃的相对氧气供应大幅增加。这与其他地方提出的论点是一致的，即鳃的相对氧气供应量的下降（其表面积无法跟上体重的增加）是成鱼生长速度随体重下降的原因。