Sockeye salmon natural selection against large bodies. Populations with higher levels of predation tend to evolve smaller body size. Without the threat of predation, salmon that breed early in the season live longer than those that breed late in the season. Other ecological factors like stranding effect select for smaller body size in sockeye salmon when present in a habitat. Stranding is when salmon swim into dry land or shallow water during their migration for spawning and die from suffocation. In fact, studies show that the Sockeye salmon with the largest bodies are most susceptible to stranding mortality. Reproduction is marked by
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