By William F. Royce (Auth.)
Read or Download Introduction to the Fishery Sciences PDF
Best oceans & seas books
For many years, marine scientists Robert and Alice Jane Lippson have traveled the interior Coast—the rivers, backwaters, sounds, bays, lagoons, and inlets stretching from the Chesapeake Bay to the Florida Keys—aboard their trawler, Odyssey . The end result in their leisurely trips, lifestyles alongside the internal Coast is a guidebook to the vegetation, animals, and habitats present in probably the most biologically assorted areas in the world.
100 years in the past, a beached whale may were greeted through a mob wielding flensing knives; this day, humans deliver harnesses and boats to assist it go back to the ocean. The whale is without doubt one of the so much awe-inspiring and clever animals in nature, sharing a posh courting with people that has considerably advanced over the centuries.
Someone who has ever stood at the seashores of Monterey Bay, gazing the rolling ocean waves and frolicking otters, understands it's a targeted position. yet even citizens in this idyllic California coast won't detect its complete historical past. Monterey started as a typical paradise, yet grew to become the poster baby for business devastation in John Steinbeck’s Cannery Row,and is now some of the most celebrated beaches on the earth.
Extra info for Introduction to the Fishery Sciences
Whether the waters do support most of the earth's photosynthesis is not known because the plants are vastly different from those on land, although we guess that photosynthesis is at about the same rate per unit area. Practically all of the plants in the waters are the minute, pelagic phytoplankton that drift throughout the surface layer. The attached algae and higher plants that occur only in shallow water along the shores comprise but a minute part of the total weight of aquatic plants, although they may be important in marshes, small lakes, or streams.
The surface layer will sink when it becomes more dense than the deeper water during the seasonal temperature changes in lakes and the pole ward movement of water in the ocean. Once below the surface a water mass remains almost constant in temperature and salinity; these properties are called "conservative" properties since they are changed only slowly by mixing processes. The masses of water that sink in the colder oceans move slowly toward the equator, so slowly that some are estimated to have been at the surface 2000 years ago !
Most of the sounds produced by animals are of low frequency varying from about 10 to 1000 Hz (cycles/second), but some produced by mammals are of frequencies ranging up to 80,000 Hz, far above the limit of human hearing (about 10,000 Hz). Sound is important to the fisherman who uses either echo-sounding or echo-ranging equipment for either navigation or fish location. ) Echo-sounding equipment is considered essential for all high-seas vessels as a navigational aid and as a help in locating fish near the bottom (Fig.
Introduction to the Fishery Sciences by William F. Royce (Auth.)