Our look is the result of reader comments, our own experimentation, and feedback from distribution channels. Distinctive covers complement our distinctive approach to technical topics, breathing personality and life into potentially dry subjects.
The animals on the cover of Practical Perforce are herring, of which there are over 200 species. In particular, the Atlantic herring (Clupea harengus) lives in the coastal waters off New England and can be found from Nova Scotia to Cape Cod.
Atlantic herring begin their lives as larvae measuring five to seven millimeters long. They emerge from an egg bed that can contain as many as seven million eggs. Tiny, scaleless, and transparent, they are weak swimmers and rely on a yolk sack for nourishment after hatching. Soon after the yolk is used up, they develop mouth parts that enable them to eat such prey as tiny plankton and the eggs and larvae of clams, shrimp, and barnacles.
The larval stage can last from 3 to 11 months (usually 6 months) depending on environmental factors such as water temperature and scarcity of food. Of the millions of eggs deposited by herring each year, it is estimated that only one percent will survive to be juvenile herring or "brits."
Usually around spring, the larvae grow into brits that look like smaller herring. Silvery blue-green scales begin to form, and their bodies grow thicker and flatter, measuring about 40 millimeters in length. At this time, the brits begin to form schools that migrate shoreward and toward the surface. The growth rates of brits are determined by the size of the school-a smaller population means the brits will grow bigger, while a crowded school means the fish will stay smaller. The brits feed on plankton at night near surface waters. They are also a virtual swimming buffet for such predators as mackerel, striped bass, puffins, and gulls. Brit schools often hide under docks and piers to escape predators.
At 3 to 4 years, brits grow into fully mature herring and measure 23 to 26 centimeters long. Some distinguishing features are a dorsal fin midway along the body and a saw-toothed keel located along the belly. Herring can live for 12 years and weigh up to 1.5 pounds. Adults migrate in schools, and in late summer and early fall they move toward the coastal waters of Maine to spawn. The spawning pattern moves from north to south, starting in the Bay of Fundy and moving to eastern Maine waters in late July and early August, or sometimes as late as November or even December.
Herring fertilize their eggs externally, with the female laying as many as 20,000 to 50,000 eggs (larger females can lay up to 200,000) that are then fertilized by the male with a substance called milt. Herring do not die after spawning but can continue to spawn for several years. Their sticky eggs sink to the ocean floor and collect in thick mats that will begin to hatch in 7 to 10 days.
Humans have fished herrings since as early as 240 A.D. and have used them both as a food source and as bait in lobster traps.
Adam Witwer was the production editor for Practical Perforce. Argosy Publishing provided production services. Sanders Kleinfeld and Claire Cloutier provided quality control.
Karen Montgomery designed the cover of this book, based on a series design by Edie Freedman, and produced the layout with Adobe InDesign CS using Adobe's ITC Garamond font. The cover image is from Cassell's Natural History.
David Futato designed the interior layout. This book was converted by Keith Fahlgren to FrameMaker 5.5.6 with a format conversion tool created by Erik Ray, Jason McIntosh, Neil Walls, and Mike Sierra that uses Perl and XML technologies. The text font is Linotype Birka; the heading font is Adobe Myriad Condensed; and the code font is LucasFont's TheSans Mono Condensed. The illustrations that appear in the book were produced by Robert Romano, Jessamyn Read, and Lesley Borash using Macromedia FreeHand MX and Adobe Photoshop CS. The tip and warning icons were drawn by Christopher Bing. This colophon was written by Jansen Fernald.
