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Abstract
Fish often undergo food shortages in nature, especially for juveniles that are relatively vulnerable in most aspects. Therefore, the effects of food deprivation on fish behavior and physiology are worth exploring. Here, we investigated the behavioral and metabolic adaptations of the juvenile black rockfish Sebastes schlegelii to different durations of food deprivation. In this study, three treatments were set: control group, short-term food deprivation (STFD) group, and long-term food deprivation (LTFD) group. The rearing lasted for six weeks. During this period, videos were recorded three times per week to assess the locomotor activity and aggression. After this, the fishes’ boldness, neophobia, and aggressiveness were assessed using different behavioral assessment devices, while the standard metabolic rate (SMR) was measured by flow-type respirometry. In general, the values of the four indicators (swimming time, the number of turns, movement number, and attack number) for the STFD group were significantly higher than those for the control and LTFD group during the same period of rearing. In a subsequent personality assessment, the STFD group was observed to be significantly bolder in an assessment measuring boldness than the control and LTFD group (indicated by time in the circle, swimming time, number of times through the circle, and frequency in the circle). The LTFD group was observed to be more exploratory in the assessment of neophobia (indicated by duration in the exploratory area, distance from novelty item, and frequency of stay in the exploratory area). Indeed, the LTFD group was observed to be significantly less aggressive in the assessment of aggressiveness than the control and STFD group (indicated by attack number, attack range frequency, first attack, and winner). SMR was noted to be significantly higher in the STFD group than in the control and LTFD group. In conclusion, this study firstly reported the effects of food deprivation duration on the personalities of black rockfish, as well as the behavioral and physiological mechanisms. Thus, we hope to provide insights into the work of stock enhancement.
Highlights
At the beginning of the rearing period, there were no significant differences in all four indicators between the control and the long-term food deprivation (LTFD) group, but at the end of the six-week rearing period, there were significant differences in all indicators between fish in the three different treatments (p < 0.05)
For movement number (MN), no significant differences were observed between the three stages
For attack number (AN), significant differences were observed between the three stages (p < 0.05), but no significant differences were observed between the early and middle stages, or between the middle and late stages
Summary
Food abundance can often cause intraspecific behavior variation [12], and this can be referred to as an ability to respond to environmental conditions by changing phenotypes (developmental plasticity) during the ontogenetic process [13]. This has been demonstrated by almost all organisms studied so far [14]. Previous experiments have shown that the environment can continuously influence phenotypic traits, and the availability of food during the juvenile stage can completely influence the entire life history of an individual [15]
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