Differences in External Morphology, Body Composition and Swimming Performance Between Hatchery- and Wild-Origin Marbled Rockfish (Sebastiscus marmoratus)

Abstract

Stock enhancement based on hatchery-reared fish has become one of the most common forms of management practices in marine fisheries resource restoration. However, unnatural rearing environments may cause hatchery-reared fish to diverge phenotypically from wild conspecifics, with negative consequences for post-release performance in the natural environments. To better evaluate the suitability of releasing hatchery-reared fish, it is necessary to understand the phenotypic effects of captive rearing, through comparisons with wild conspecifics. In this study, we compared body morphology, swimming performance, and biochemical body composition between hatchery-reared and wild marbled rockfish (Sebastiscus marmoratus) from the same general gene pool. The results show that the overall body profile differed significantly between the groups, with hatchery-reared individuals having a deeper body (in particular in the head and trunk regions), narrower caudal peduncles, and higher condition factor, as compared to wild conspecifics. Hatchery-reared marbled rockfish also had relatively shorter fins, for a given size. In terms of swimming performance, the hatchery-reared marbled rockfish performed worse than the wild, with slower burst swimming speeds and poorer endurance. Wild rockfish had higher body protein content but lower lipid levels compared to the hatchery-reared individuals. These results suggest that hatchery rearing conditions have a great impact on the phenotypic development, with possibly high effects on their post-release performance of the hatchery-reared marbled rockfish. Modifications for the hatchery environment and operation should be investigated with an aim to minimize the divergence in phenotypic development for production of more wild-like fish for stocking.

Disparities in Body Color Adaptability and Ambient Light Color Preference between Wild and Hatchery-Reared Marbled Rockfish (Sebastiscus marmoratus)

“…The marbled rockfish Sebastiscus marmoratus is a benthic reef species widely distributed in the inshore regions of the East China Sea [ 33 ]. Sharing ecological traits with other members of the Sebastini tribe, it favors demersal rocky habitats, employing cryptic coloration for camouflage [ 34 , 35 , 36 ]. In China and Japan, it ranks among the most popular recreational fish species [ 37 ].…”

“…However, overfishing has precipitated a sharp decline in its wild populations [ 38 , 39 ]. Recent advancements in aquaculture techniques have led to small-scale stocking trials in eastern China, aimed at assessing the viability of supplemental rearing and stocking prior to broader implementation [ 36 , 40 ]. Nonetheless, our prior research has identified notable discrepancies, including notes on body color, between hatchery-reared and wild individuals, potentially compromising the post-release success of cultured fish in natural environments [ 36 ].…”

“…Recent advancements in aquaculture techniques have led to small-scale stocking trials in eastern China, aimed at assessing the viability of supplemental rearing and stocking prior to broader implementation [ 36 , 40 ]. Nonetheless, our prior research has identified notable discrepancies, including notes on body color, between hatchery-reared and wild individuals, potentially compromising the post-release success of cultured fish in natural environments [ 36 ]. Given the documented influence of ambient light color on fish physiology and behavior [ 8 , 9 , 10 , 11 , 41 ], elucidating the differences in body color regulation and phototactic responses between wild and hatchery-reared marbled rockfish assumes significant importance, offering insights into the mechanisms governing fish coloration.…”

Continuous flow stimulation had no significant effect on the growth rate but was conducive to the swimming performance, spontaneous behavior, and nonspecific immune parameter of juvenile Percocypris pingi

“…In addition to promoting growth performance, another main aim of swimming training research is to increase the survivability of fish when they are released into their natural habitat (Davison, 1997). The swimming capacity of farmed fish is worse than that of wild individuals due to high breeding density and smaller activity space (Guo et al, 2022; Jonsson et al, 2003). Poor swimming capacity in farmed fish reduce their antipredation ability, which in turn leads to low survival rates when they are transferred to natural waters (Davison, 1997; Miller et al, 2004).…”