In marine aquaculture, what is the typical salinity expressed in ppt?

• A. 20-25
• B. 30-35
• C. 40-45
• D. 50-55

Answer: (B)

Salinity is measured in parts per thousand, and seawater is typically around 35 ppt. Marine aquaculture systems are usually operated near this seawater salinity so the osmotic balance for most marine organisms remains stable, supporting normal metabolism, growth, and health. The 30-35 ppt range aligns with the salinity level that many finfish and invertebrates are adapted to in the wild, making it the standard for cultured marine species. Values much lower, like 20-25 ppt, are brackish and not ideal for most marine organisms, while much higher salinities such as 40-45 ppt or 50-55 ppt can cause osmotic stress and reduced performance. So the typical salinity expressed in ppt for marine aquaculture is 30-35.