In Japan, the whitebait (しらす/白子, shirasu) fishing industry is concentrated in Shizuoka Prefecture, where the major landing ports for them are situated. The shirasu boiled in salted hot water is called kamaage shirasu (釜上げしらす, boiled whitebait), and this product retains about 85% or greater water ratio.
The boiled whitefish which are subsequently semi-dried are referred to generally as shirasuboshi (しらす干し, literally 'dried whitebait'), but this is in the wider sense of the term; in the stricter sense shirasuboshi (aka Kantō boshi, or 'Eastern Japan style dried') refers to soft-dried products (50–85% water ratio), and distinguished from chirimen-jako () (aka Kansai boshi or 'Western Japan style dried') which are dried to harder consistency (30% to shy of 50% water content.)
The whitebait used in these shirasu products is generally the larvae of the Japanese anchovy, but in the vernacular Japanese language anchovy (片口, katakuchi iwashi) is called a type of sardine (, iwashi), thus shirasu may be (somewhat misleadingly) described as sardine fry in some literature, though of course the larvae of clupeids do occur as bycatch in the shirasu being harvested.The shirasu landed in Shizuoka Prefecture consists of the 2–3 month old, and 1–2 cm length larvae of mostly Japanese anchovy, and a small proportion of Japanese pilchard (真, ma iwashi), Sardinops sagax melanostictus, a subspecies of sardine.
One specialty product is the tatami iwashi (たたみいわし, literally 'tatami sardine'), a paper-thin square wafer made from uncooked dry shirasu, spreading the washed fish thinly inside square molds then drying them, which has become a pricey delicacy.
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