Short answers, pulled from the story.
The name sardine originates from the red gemstone sardonyx or sard, which was prized in ancient times for its reddish-brown hue. This stone possibly shares its name with the ancient city of Sardis in western Turkey, creating a linguistic connection that stretches back to Ancient Greek. The word first appeared in English during the early 15th century, derived from the French sardine and the Latin sardina.
The term sardine applies to various species across multiple genera within the herring suborder Clupeoidei. The Food and Agriculture Organization of the United Nations cites 21 species that may be classed as sardines, while FishBase identifies at least six species as pilchards and over a dozen simply as sardines. Genera such as Dussumieria, Escualosa, Sardina, Sardinella, and Sardinops all contain species that may be called sardines or pilchards depending on the region.
Sardines are typically caught with encircling nets, particularly purse seines, and are harvested mainly at night when they approach the surface to feed on plankton. After harvesting, the fish are submerged in brine while they are transported to shore to preserve their quality for further processing. The chief use of sardines is for human consumption, but they are also used for fish meal, oil, drying, salting, or smoking.
The sardine canning industry in the United States peaked in the 1950s, with canneries in Monterey Bay failing in the mid-1950s. The last large sardine cannery in the United States, the Stinson Seafood plant in Prospect Harbor, Maine, closed its doors on the 15th of April 2010 after 135 years in operation. In April 2015, the Pacific Fishery Management Council voted to halt the current commercial season in Oregon, Washington, and California due to a dramatic collapse in Pacific sardine stocks.
The phrase packed like sardines appears in The Mirror of Literature, Amusement, and Instruction from 1841 and is a translation of a French text from 1829. Other early appearances include packed together like sardines in a tin-box from 1845 and packed like sardines in a can from 1854. The phrase reflects the cultural impact of sardine canning on language and idioms, describing situations where people or objects are crowded closely together.