Chapter 9: Methods Used to Study the Ocean Ecology of Pacific Salmon and Trout
Thomas Royer, Nancy D. Davis, Masa-aki Fukuwaka, Robert V. Walker, Dion S. Oxman, Kevin W. McNeel, Andrew R. Munro, Lisa W. Seeb, William D. Templin, Christopher Habicht, Fred M. Utter, James E. Seeb, Marc Trudel, Strahan Tucker, Alexander V. Zavolokin, Richard D. Brodeur, and James R. Irvine
Ocean physics can affect Pacific salmon Oncorhynchus spp. productivity through the transport of smolts and adults by ocean currents and the distribution or productivity patterns of planktonic salmon food. Physical oceanography can also affect the growth of salmon by altering its metabolism through water temperature changes. Ocean currents affect and are affected by water density. Therefore the distributions of temperature and salinity throughout the water column, which affect the density of the water column, are also important. Basic physical ocean parameters are currents, temperature (T) and salinity (S) versus depth (D). Density patterns determine one of the components of ocean currents or vice versa. T, S, and D are often referred to as the hydrographic properties.
The abilities to sample currents, temperature, salinity, and depth within the marine environment have improved dramatically in the last several decades. Awkward water sampling and chemical titrations have been replaced by more accurate, higher-resolved methods. Satellites provide new approaches to ocean measurements. However, older oceanographic data archives contain data that were obtained using earlier, more primitive methods, so discussions of those methods will be included in this section.