Whales in D&D 3rd Edition were significantly reduced in Hit Dice from the way that they appeared in AD&D 1st Edition (as presented in the AD&D 1st Edition Dungeon Master's Guide, p. 214). It's doubly odd because in so doing, the designers made whales the only creatures in the Core Rules with Hit Dice falling below the "standard hit dice progression" for their size category (see here: monster_abnormal_hd). For those DMs and players who wish to clear up these problems, the following conversions are offered.
Whale, Black: Gargantuan Animal; CR 6; HD 18d8+126; hp 207; Init +1; Spd swim 40 ft.; AC 16; Atks tail slap +21 (1d8+18); Face/Reach 20x40 ft./10 ft.; SQ Blindsight; AL N; SV Fort +18, Ref +12, Will +8.
Str 35, Dex 13, Con 25, Int 2, Wis 14, Cha 6.
Skills and Feats: Listen +11*, Spot +12*.
Advancement: 19-23 HD (Gargantuan).
Whale, Humpback: Gargantuan Animal; CR 7; HD 26d8+208; hp 325; Init +1; Spd swim 40 ft.; AC 16; Atks tail slap +29 (2d6+21); Face/Reach 20x40 ft./10 ft.; SQ Blindsight; AL N; SV Fort +23, Ref +16, Will +9.
Str 39, Dex 13, Con 27, Int 2, Wis 12, Cha 6.
Skills and Feats: Listen +10*, Spot +11*.
Advancement: 27-31 HD (Gargantuan), 32-33 HD (Colossal).
Whale, Killer: Huge Animal; CR 6; HD 12d8+60; hp 114; Init +1; Spd swim 50 ft.; AC 16; Atks bite +15 (2d6+12); Face/Reach 10x20 ft./10 ft.; SA Improved grab, swallow whole; SQ Blindsight; AL N; SV Fort +13, Ref +10, Will +6.
Str 27, Dex 15, Con 21, Int 2, Wis 14, Cha 6.
Skills and Feats: Listen +12*, Spot +12*.
Advancement: 13-15 HD (Huge).
Whale, Right: Gargantuan Animal; CR 6; HD 20d8+140; hp 230; Init +1; Spd swim 40 ft.; AC 16; Atks tail slap +23 (1d8+18); Face/Reach 20x40 ft./10 ft.; SQ Blindsight; AL N; SV Fort +19, Ref +13, Will +7.
Str 35, Dex 13, Con 25, Int 2, Wis 12, Cha 6.
Skills and Feats: Listen +10*, Spot +11*.
Advancement: 21-26 HD (Gargantuan).
Whale, Sperm: Gargantuan Animal; CR 9; HD 29d8+232; hp 362; Init +1; Spd swim 40 ft.; AC 16; Atks bite +31 (2d8+21), or tail slap +31 (2d6+21); Face/Reach 20x40 ft./10 ft.; SA Improved grab, swallow whole; SQ Blindsight; AL N; SV Fort +24, Ref +17, Will +11.
Str 39, Dex 13, Con 27, Int 2, Wis 14, Cha 6.
Skills and Feats: Listen +11*, Spot +12*.
Advancement: 30-31 HD (Gargantuan), 32-36 HD (Colossal).
Whale, White (Beluga): Huge Animal; CR 6; HD 12d8+60; hp 114; Init +1; Spd swim 50 ft.; AC 16; Atks bite +15 (2d6+12); Face/Reach 10x20 ft./10 ft.; SA Improved grab, swallow whole; SQ Blindsight; AL N; SV Fort +13, Ref +10, Will +6.
Str 27, Dex 15, Con 21, Int 2, Wis 14, Cha 6.
Skills and Feats: Listen +12*, Spot +12*.
Advancement: 13 HD (Huge).
Skills: Whales gain a +4 racial bonus to Spot and Listen checks. *These bonuses are lost if Blindsight is negated.