Tyler R. Goodearly

Regenerating complex tissues requires coordination between local cellular responses and body-wide systemic signals. As a central endocrine regulator, the pituitary is well positioned to coordinate this process. Here, we identify the pituitary as an injury-responsive regulator of axolotl limb and tilapia fin regeneration. Limb loss triggered sustained transcriptional responses in the axolotl pituitary. Single-cell transcriptomics linked pituitary loss to altered gene expression in prolactin- and growth hormone-responsive limb cells. Local disruption of the prolactin receptor impaired digit formation, whereas combined hormone treatment partially restored regeneration in hypophysectomized axolotls. In tilapia, pituitary removal impaired fin regeneration and prolactin-related signaling. Mouse digits differed from axolotls and tilapia in how and when they received pituitary signals during regeneration, suggesting pituitary-dependent regrowth is evolutionarily divergent among highly regenerative vertebrates.

Recent increases in demand for sustainable aquaculture have been accompanied by a rising interest in its practice, including the continued development of inland recirculating aquaculture systems (RAS). The transfer of knowledge necessary to optimize learning outcomes for aquaculture students and practitioners relies on accessibility to versatile state-of-the art facilities. A new land-based aquaculture facility called the Tuahine Aquaculture Research and Education Center (TAREC) was built at the University of Hawaiʻi at Mānoa and designed to integrate research, education, and extension activities. With two RAS and a compact footprint, TAREC was designed to hold freshwater (FW), seawater (SW), or both FW and SW aquatic organisms simultaneously, including the option for modifications along a salinity gradient under experimental conditions. An account of the requirements and specifications for building the system is provided along with an initial trial comparing growth rates of the euryhaline Mozambique tilapia, Oreochromis mossambicus , reared in FW and artificial seawater (ASW) when stocked at ~0.6 kg/m3. Over three months, fish reared in ASW grew faster and had lower feed conversion ratios than those in FW. These findings not only validate salinity-dependent growth trials in RAS but also demonstrate TAREC’s capacity as a versatile experimental facility for conducting fundamental and applied research and training for the next generation of aquaculture researchers and practitioners.

The life history, distribution and diversity of fishes are largely influenced by environmental salinity. Changes in salinity affect a range of physiological processes including metabolism, nutrition, reproduction and growth. Therefore, fish can be conditioned to environmental parameters most suitable for production, where distinct traits are optimised through species‐specific manipulation of salinities. The primary purpose of this review is to summarise the existing literature on the salinity tolerance of aquacultured fish. The various experimental approaches for determining salinity tolerance are compared, along with summarised information for key species employed in aquaculture, including their native distributions, life history stage and optimal salinity for survival and growth. The implications for production were assessed by considering the effects of salinity on growth, reproduction, management, disease mitigation and marketability.