Sockeye salmon are red, which is the usual color of females. Even small changes in wavelength, saturation, and brightness can affect preference. Both sexually naïve males and experienced males showed the same preferences, which illustrates that preference for a red hue may be innate. Some traits that lead to reproductive success, such as body size and sexual dimorphism can affect one’s survival. This leads to opposing pressures of natural selection and sexual selection. Larger males are favored, unless the risk of predation is very high. Sockeye salmon that die prematurely from predation are typically the larger ones in a population. This shows
Fish tug the 1930s it became common to add a pilothouse amidship or near the stern, and to continue the cabin covering to the bow in what was known as a "sprayhood." Steel-hulled boats began to replace wooden-hulls in the late 1950s. Beginning in the 1970s, new regulations began to greatly restrict gill-net fishing, making the fish tug all but obsolete. The few fish tugs that remain in use today are largely objects of historical preservation efforts and not under commercial ownership. Fish tug A fish tug (sometimes called fishtug, fish tugboat, fishing tug, etc.) is a type of boat that was