Defining Stock
In fisheries management, stock refers to a harvested or managed unit of a fish. Typically stocks are divided based on geographical location and not based on individual population. Spanish mackerel are distributed from Maine to the Yucatan Peninsula in Mexico. They are divided into two stocks, based on whether they migrate northward along the eastern United States coast or if they migrate into the Gulf of Mexico. Each stock of Spanish mackerel does not represent discrete populations. Stocks are not always composed of a single species. Stocks can be composed of multiple species due to their being harvested together or as a form of convenience for managers. An example of a multispecies stock is river herring. Alewives and blueback herring are labeled as river herring for management purposes due to their similar physical appearances and being harvested together. Individuals within a stock are subdivided into cohorts. A cohort is a group of fish born in the same year within a population or stock.
Read more about this topic: Stock Assessment
Famous quotes containing the words defining and/or stock:
“The U.S. is becoming an increasingly fatherless society. A generation ago, an American child could reasonably expect to grow up with his or her father. Today an American child can reasonably expect not to. Fatherlessness is now approaching a rough parity with fatherhood as a defining feature of American childhood.”
—David Blankenhorn (20th century)
“I’d rather I were dead and gone,
And my body laid in grave,
Ere a rusty stock o coal-black smith
My maidenhead should have.”
—Unknown. The Twa Magicians (l. 17–20)