The Reproductive Strategy of the Rare Minnow (Gobiocypris rarus) in Response to Starvation Stress.

Abstract

Food abundance plays an important role in the reproduction of fish, especially multiple spawners. Multiple spawners can exhibit various biological strategies when under starvation stress. However, the reproductive strategy used in these fish species remains unknown. To explore whether rare minnows (Gobiocypris rarus) prioritize survival over current reproduction under starvation conditions, paired adult rare minnows were starved for 0, 5, 10, 15 d and their spawning activities were recorded. Anatomical and histological characteristics of unpaired adult rare minnows were examined during starvation and following re-feeding. It was found that only 30-70% of paired rare minnows spawned within 5 d after deprivation of food. Though spawning activity was suppressed by starvation, rare minnows starved for 0, 5, 10, and 15 d waited 3.89 ± 0.78 d, 5.57 ± 3.36 d, 5.83 ± 5.15 d and 6.57 ± 4.50 d, respectively, after re-feeding to resume spawning. The average inter-spawning interval and length until egg production of those starved for 15 d was 4.60 ± 2.37 d and 139.1 ± 67.9 d, respectively, when they spawned with rhythm, which were significantly different from those starved for 0 d (P < 0.05). Anatomical and histological data further revealed that late maturing oocytes degraded after 8 d of starvation, but the gonadosomatic index recovered to initial levels after 8 d of re-feeding. Thus, reproduction of rare minnows was markedly affected by starvation, but rapidly returned to normal upon re-feeding. These observations demonstrated that paired rare minnows prioritize survival by channeling energy from the liver and absorbing late maturing oocytes instead of continuing to reproduce under food deprivation condition.