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Selection for Surface Feeding in Farmed and Sea‐Ranched Masu Salmon Juveniles
Author(s) -
Reinhardt Ulrich G.
Publication year - 2001
Publication title -
transactions of the american fisheries society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 86
eISSN - 1548-8659
pISSN - 0002-8487
DOI - 10.1577/1548-8659(2001)130<0155:sfsfif>2.0.co;2
Subject(s) - fishery , selection (genetic algorithm) , biology , zoology , computer science , artificial intelligence
The feeding behavior of Japanese masu salmon Oncorhynchus masou (also known as cherry salmon) 3–4 months old differed among fish from wild, farmed, and sea‐ranched parents. Between feeding intervals, wild‐derived fry groups stayed lower in their separate stream tanks than farmed or ranched fry. When slow‐sinking food was offered, the wild fry made foraging bouts from the bottom, whereas the domesticated (farmed and sea‐ranched) fry stayed close to the surface. Consequently, the domesticated fry finished their meal faster than the wild fish. Over time, all stocks moved up higher in the water column and fed faster, but a difference between wild and domesticated fish persisted. Levels of aggression were similar among the three stocks and observation periods. Sea‐ranched fish were intermediate between wild and farmed fish in most recorded behaviors. Staying close to the water surface obviously is a successful strategy under standard salmon husbandry conditions, but an innate tendency to seek the surface is probably maladaptive in the wild. New hatchery techniques that teach fish to avoid the surface or prevent selection for surface‐seeking behavior promise to bolster the survival of postrelease ranched salmon.