Hogfish (Lachnolaimus maximus), a popular sport and food fish, are highly sought after by anglers and have historically experienced overfishing through parts of their range. Aquaculture and stock enhancement are potential tools that can be used to supplement wild harvest and improve wild stocks, but limited understanding of biological and technical aspects of hogfish culture has stymied these efforts. We sought to characterize the osmoregulatory capacity of hogfish as osmoregulation can be metabolically expensive and limit somatic growth and production efficiency. Culturing fish in isosmotic environments could reduce bioenergetic requirements, thereby improving growth. To better understand this capacity in hogfish we conducted four experiments: survival after acute salinity transfers from 32 g/L to 4, 8, 16, 24, & 32 g/L, physiological (plasma chloride, plasma osmolality, muscle water content, and hematocrit) tolerance of acute transfer to 8 g/L, physiological tolerance of gradual transfer to 12 g/L, and finally an exploration of low salinity culture at 16 g/L and 32 g/L to assess effects on growth and feed conversion.
Results of these experiments show hogfish survived at ≥8 g/L for 96 hours (Fig. 1), however, plasma chloride, plasma osmolality, and muscle water content were significantly altered at 8 g/L and mortalities were noted during long term retention at 8 g/L. Gradual transfer to 12 g/L yielded no significant physiological alterations compared with acute transfer to the same salinity for the parameters measured. Furthermore, growth indices for hogfish in 16 g/L and 32 g/L were similar though the variance in metrics suggest a need for further exploration. This suggests that hogfish should be tolerant of rapid transfer to salinities as low as 12 g/L and that growth may be unaffected by low salinity culture down to 16 g/L salinity. Results from this research will help guide future aquaculture and stock enhancement efforts for hogfish and add to the growing body of literature for this valuable marine species.