Association of Aquaculture Environment Microbiota with Metabolism in American Shad (Alosa Sapidissima)

The environment microbiome affects the growth and development of fish species. Information of the environment microbiome is beneficial to increase the production of fish in different aquaculture systems. In this study we analyzed differences in environmental microbial composition, intestinal metabolites and differentially expressed genes (DEGs) in American shad living in tank aquaculture and pond aquaculture environment. The results demonstrated that the dominant phyla were Bacteroidetes, Actinobacteria, Fusobacteria, Gemmatimonadetes, Firmicutes, Acidobacteria, Nitrospirae and Epsilonbacteraeota in two different environments. There were significantly changed of metabolites in different aquaculture environment, including DP-ethanolamine, L-proline, sulfuric acid, L-valine, L-tryptophan, creatinine, uric acid and L-isoleucine. The transcriptome data revealed eight genes (As23G026314, As04G005148, As21G024434, As04G005193, As23G026314, As13G016035, As02G001872 and As07G009244) related to metabolisms significantly changed in pond aquaculture group compared to tank aquaculture group. In addition, the body weight, amino acid metabolism, and glycerophospholipid metabolism of American shad also significantly changed in the pond aquaculture environment. Therefore, identifying the predominant microbiome in the aquaculture environment may be prevent the disease from occurring and maintain healthy fish reared in the aquaculture environment.

The Susceptibility of Juvenile American Shad to Rapid Decompression and Fluid Shear Exposure Associated with Simulated Hydroturbine Passage

Throughout many areas of their native range, American shad (Alosa sapidissima) and other Alosine populations are in decline. Though several conditions have influenced these declines, hydropower facilities have had significant negative effects on American shad populations. Hydropower facilities expose ocean-migrating American shad to physical stressors during passage through hydropower facilities, including strike, rapid decompression, and fluid shear. In this laboratory-based study, juvenile American shad were exposed separately to rapid decompression and fluid shear to determine their susceptibility to these stressors and develop dose–response models. These dose–response relationships can help guide the development and/or operation of hydropower turbines and facilities to reduce the negative effects to American shad. Relative to other species, juvenile American shad have a high susceptibility to both rapid decompression and fluid shear. Reducing or preventing exposure to these stressors at hydropower facilities may be a potential method to assist in the effort to restore American shad populations.

How lipid content and temperature affect American shad (Alosa sapidissima) attempt rate and sprint swimming: implications for overcoming migration barriers

How seasonal effects such as temperature increases and reduced lipid content affect the ability of anadromous fishes to traverse high-velocity barriers and sprint swimming is poorly understood. We evaluated American shad (Alosa sapidissima) swimming performance in a flume against high flow velocities (2.5–3.7 m·s−1) during the upstream migration period (April–May; temperatures 11.1–21.4 °C) to determine how their willingness to enter a velocity barrier (attempt rate) and their swimming endurance changed during migration. American shad did not make attempts at low temperatures, and attempt rate gradually increased throughout the migration as temperatures warmed. American shad displayed two distinct, nonsustained swimming modes (prolonged and sprint swimming), and endurance was different between sexes. At warmer temperatures, females swam at prolonged speeds more often and longer females displayed a lower endurance. Males primarily swam at sprint speeds and were affected by swimming speed, fork length, and lipid content. Our results indicate that American shad motivation and swimming endurance change over the course of the migration as conditions change, potentially limiting their ability to pass barriers.