Structural complexity in relation to the habitat preferences, territoriality, and hatchery rearing of juvenile China rockfish (Sebastes nebulosus)

Abstract

Conservation efforts require an understanding of the basic behavior and ecology of target species. However, limited information exists for a wide range of taxa, including declining species of rockfish (genus Sebastes). First, we observed captive juvenile China rockfish (S. nebulosus) to determine how they interact with their environment and conspecifics. Juveniles exhibited site fidelity and territoriality. These aggressive interactions occurred within the context of size-biased dominance, centered on competition for structurally complex habitat. Given the apparent importance of structure and the absence of structure in typical hatchery environments, we then asked how the absence of structure affects future behavior. When barren-reared and structure-reared juveniles were combined into a structurally complex aquarium, barren-reared fish displayed less structure use and less site fidelity than structure-reared fish. However, after 1 to 2 weeks, barren-reared fish began to use structure and showed site fidelity that eventually equaled that of structure-reared juveniles, showing that those behavioral effects of the rearing environment were not permanent. Though these short-term effects may still impact survival after hatchery release, we were unable to detect significant effects on vulnerability to a predator (lingcod, Ophiodon elongatus) in laboratory trials.

Behaviourally Mediated Phenotypic Selection in a Disturbed Coral Reef Environment

“…Analysis showed no significant difference in aggression with habitat, however there was approximately 48% greater difference in mean aggression levels between large and small fish on bleached coral. It is not uncommon to find that intra-peer aggression varies with habitat [57] , [58] since subtle differences in habitat influence predation risk [59] and the potential importance of specific areas as key refuge sites. This study is the first to underscore the important role played by behavioural interactions between cohort members immediately after settlement in driving the dynamics of post-settlement mortality, phenotypic selection profiles and post-settlement distribution patterns.…”

Fish behavioral types and their ecological consequences

“…Individuals that were reared with physical structure, fed natural prey, and subjected to simulated attacks showed decreased boldness relative to individuals raised under conventional hatchery conditions (Roberts et al 2011). When comparing both the presence and stability of physical structure during rearing, Lee and Berejikian (2009) found that stable structures (the "unstable" treatment moved structure throughout the experiment) were important for individuals to assess current risk and display behaviors accordingly. Individuals reared with stable structure were more explorative without predators but showed reduced exploration under predation threat.…”

“…The process of raising juvenile fish in hatchery environments has been shown to affect the cognitive pathways that influence behavior (Huntingford and Adams 2005). Enrichment strategies, such as providing physical structure, decreasing fish densities, feeding with live prey, and introducing simulated predator at-tacks, have been suggested to better prepare hatchery fish for stocking (Brown et al 2003;Lee and Berejikian 2009;; see review in Huntingford 2004). All of these modifications to current hatchery conditions have been shown to benefit hatchery-reared fish in ways that could increase post-stocking survival.…”

Social enrichment affects fish growth and aggression depending on fish species: Applications for aquaculture

“…For each day, only one 10-min video was randomly filmed between 11:00 a.m. and 2:00 p.m. Although it is commonly adopted by related studies (Lee and Berejikian, 2009;Barley and Coleman, 2010;Batzina and Karakatsouli, 2012;Bilhete and Grant, 2016;Zhang et al, 2020a), this method may still cause some bias in the intensity of fish behaviors because fish activity has a specific rhythm and is meanwhile affected by environmental factors (e.g., feeding). To weaken the effects of diel rhythm and environmental disturbance, we collected behavior data in a completely random order for aquaria during intervals of feeding.…”