Bank of Hawaii ( BOH) said its first-quarter earnings fell 19.9%, hurt by shrinking margins and a tax charge. The company earned $37.2 million, or 73 cents a share, compared with $46.4 million, or 87 cents a share, in the year ago period. Results for the quarter include a charge of about $9 million, or 17 cents a share as a result of the recently enacted Tax Increase Prevention and Reconciliation Act. Analysts polled by Thomson First Call were expecting earnings of 86 cents a share. First-quarter net interest margin fell 11 basis point to 4.25%, due to flattening yield curve, a shift in the funding mix and a tax charge. Net interest income fell to $99.9 from $101 million, hurt by increased deposit costs and a tax charge, the company said. Noninterest income rose 5% to $53.2 million in the quarter. Noninterest expense in the most recent quarter fell margianlly to $78.7 million. The company lowered its full-year earnings guidance to $178 million, due to a $9 million tax adjustment. Analysts expected revenue of $187.5 million. Total deposits at the end of the quarter were $7.77 billion, up from $7.73 billion last year.