
1) Salmon variety
Found on
https://www.crosswordclues.com/clue/blueback

• (n.) An American river herring (Clupea aestivalis), closely allied to the alewife. • (n.) A salmon (Oncorhynchus nerka) of the Columbia River and northward. • (n.) A trout (Salmo oquassa) inhabiting some of the lakes of Maine.
Found on
http://thinkexist.com/dictionary/meaning/blueback/

common name for a number of blue-coloured fishes, particularly the lake herring, or cisco, a whitefish (q.v.); the summer, or glut, herring (see ...
Found on
http://www.britannica.com/eb/a-z/b/82
Blue'back` noun (Zoology) (a) A trout (
Salmo oquassa ) inhabiting some of the lakes of Maine.
(b) A salmon (
Oncorhynchus nerka ) of the Columbia River and northward.
(c) An American river herring (
Clupea æstivalis ), closely allied to the alewife. ...
Found on
http://www.encyclo.co.uk/webster/B/70

USS Blueback was an American Balao Class submarine of 1525 tons displacement launched in 1944 which saw action during the Second World War. USS Blueback was powered by diesel engines providing a top speed of 21 knots, carried a complement of 75 and was armed with one 4-inch gun, two 20 mm Oerlikon anti-aircraft guns; six 21 inch bow torpedo tubes a...
Found on
http://www.probertencyclopaedia.com/browse/RB.HTM
No exact match found.