The sardine is a paradoxical fish. Seemingly insignificant, its exploitation has made fortunes for some and, when stocks have collapsed, caused hardship for many.

Its status has shifted from utilitarian food to a gourmet's delight. Trevor Day - diver, fish-watcher and marine conservationist - travels across four continents to meet the sardine in its natural environment, and he traces the fish's journey from miniscule egg to item on the dinner plate. Sardine interweaves the story of the fish with the rise and fall of fishing industries. The sardine is a barometer for the health of oceans, with lessons for us all about our stewardship of the seas.

Day takes a scientifically and culturally wide-ranging look at the cluster of fish species called sardines, their relationship with other marine creatures and, in turn, with us. Elite predators feast on sardines, yet these silvery slivers are fast-breeding and opportunistic enough to survive their hunters. Whether swimming free as a shoaling fish at the mercy of predators, or tightly packed in tins - an image used frequently as a metaphor for overcrowding - sardines represent conformity and vulnerability. The biography that emerges will beguile readers fascinated with marine life as well as those who have eaten this familiar yet under-appreciated fish.