The physiological responses of surf smelt (Hypomesus pretiosus) to environmental stress in Puget Sound, WA, USA

Drastic environmental changes can severely affect a fish's metabolism, growth, reproduction and overall survivability. There is a concern that the synergy of multiple stressors, like the threat of climate change, will lead to population collapses of environmentally sensitive species such as forage fish. Forage fish are vital to ocean health and stability; they serve as prey and transfer energy to higher trophic levels, and are targeted globally as some of the most economically important fisheries. The surf smelt (Hypomesus pretiosus) is a crucial forage fish in the Puget Sound, WA as it is one of three forage fishes in the Sound and is a critical food source for native predatory fish, birds and mammals. Four stress related proteins (Caspase 3, HSP 70, GST and ubiquitin) were used to assess overall population health of surf smelt in the Puget Sound. GST, HSP70 and ubiquitin abundance increased with collection site temperature (p≤0.001). Caspase 3 abundance increased with collection site salinity (p0.001). There was previously undescribed presence of marine parasitic isopods embedded in the gills of the surf smelt as well. It can be concluded that the Puget Sound is potentially a stressful environment for surf smelt. As abiotic variability continues to increase in the wake of climate change, it will become of greater importance to continually monitor the population health forage fishes such as the surf smelt at the sublethal level, when there is still potentially a chance for recovery.