A novel development of the Staaland Device for testing salinity preference in fish

Abstract

A cylindrical salinity selection laboratory device with a height of 1 m and a diameter of 6 m was designed and tested. The cylinder was subdivided into six chambers (Chamber #1–6) with equal size and the same shape. The center of the cylinder was Chamber #7 in the shape of a hexagon. Six openings with 40 cm in height and 1 m in width connected Chambers #1–6 with Chamber #7. A six-face pyramid-shaped obstacle was located in the center of Chamber #7. The walls (Vertical Divider C) in the center of Chamber #7 were 50 cm. In undisturbed condition, salinities in Chambers #1–6 were stable for more than 10 d. Under the condition of continuous aeration and disturbance from laboratory fish, salinities in Chambers #1–6 were steady for 1 d. The salinity of the chamber where the largest percentage of time was spent was considered the preferred salinity of the fish. The salinity preference of juvenile Chinese sturgeon (Acipenser sinensis) reared in freshwater and 10‰ brackish water was tested using the device. Freshwater juveniles preferred freshwater absolutely and 10‰-salinity-acclimatized juveniles displayed strong tendencies towards 10‰ brackish water. These results conformed to expected preferences. The results showed that the apparatus accurately tested the salinity preference of fish. This indicates that the device described will be useful in the study of osmotic adjustments and the salinity preferences of aquatic animals in the laboratory.