(Adds comment, details, table, byline) By Gertrude Chavez-Dreyfuss NEW YORK, April 6 (Reuters) - Speculators' net short U.S. dollar bets fell for a second straight week, according to calculations by Reuters and Commodity Futures Trading Commission data released on Friday. The value of the net short dollar position was $20.71 billion in the week to April 3, compared with $21.73 billion in the previous week. The market has been short the dollar since the middle of July last year. U.S. dollar positioning was derived from net contracts of International Monetary Market speculators in the yen, euro, British pound, Swiss franc and Canadian and Australian dollars. In a wider measure of dollar positioning that includes net contracts on the New Zealand dollar, Mexican peso, Brazilian real and Russian rouble, the U.S. dollar posted a net short position valued at $24.966 billion, down slightly from $25.868 billion the week before. Dollar positioning was consistent with the currency's recovery over the last two weeks, posting gains of about 0.7 percent. For the year, though, the dollar remained down more than 2 percent. Traders, however, believed this week's moves in the futures market were a result of position adjustment after accumulating extreme shorts on the dollar in the last few months. Overall, the dollar's outlook continued to be weak. The trade dispute between the United States and China has hurt the dollar's prospects, obscuring any benefit derived from a Federal Reserve that's on a tightening path. "By the middle of next year, we think that the prospect of slower growth in the U.S. economy will bring the Fed's tightening cycle to an end while other major central banks are closer to, or in the process of, tightening policy," Oliver Jones, markets economist, at Capital Economics said. "This would probably see the gap in expected interest rates between the US and other advanced economies move against the dollar." In other currency pairs, dollar/yen positioning switched to a net long of 3,572 contracts this week Meanwhile, speculators' net short position on bitcoin Cboe futures rose to 1,786 contracts from 1,490 the previous week, the data showed. Bitcoin continues to slide, down 2.4 percent at $6,606.70 on Friday on the Bitstamp platform, after hitting a record high just shy of $20,000 in December last year. It has lost more than 50 percent of its value in 2018, with other crypto currencies such as ether and ripple also hurt by regulatory scrutiny around the world. Japanese Yen (Contracts of 12,500,000 yen) $-0.419 billion April 3, 2018 Prior week week Long 48,053 56,544 Short 44,481 60,212 Net 3,572 -3,668 EURO (Contracts of 125,000 euros) $-20.609 billion April 3, 2018 Prior week week Long 221,327 234,656 Short 86,946 93,592 Net 134,381 141,064 POUND STERLING (Contracts of 62,500 pounds sterling) $-3.544 billion April 3, 2018 Prior week week Long 86,643 90,239 Short 46,305 56,063 Net 40,338 34,176 SWISS FRANC (Contracts of 125,000 Swiss francs) $1.292 billion April 3, 2018 Prior week week Long 17,908 15,992 Short 27,819 25,437 Net -9,911 -9,445 CANADIAN DOLLAR (Contracts of 100,000 Canadian dollars) $2.489 billion April 3, 2018 Prior week week Long 29,558 33,518 Short 61,430 60,568 Net -31,872 -27,050 AUSTRALIAN DOLLAR (Contracts of 100,000 Aussie dollars) $0.006 billion April 3, 2018 Prior week week Long 46,152 51,072 Short 46,227 42,998 Net -75 8,074 MEXICAN PESO (Contracts of 500,000 pesos) $-2.719 billion April 3, 2018 Prior week week Long 136,812 130,264 Short 37,732 40,477 Net 99,080 89,787 NEW ZEALAND DOLLAR (Contracts of 100,000 New Zealand dollars) $-1.333 billion April 3, 2018 Prior week week Long 32,948 32,749 Short 14,571 14,510 Net 18,377 18,239 (Reporting by Gertrude Chavez-Dreyfuss Editing by Susan Thomas)