Browsing by Subject "Illuminated cages"
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The Israeli Journal of Aquaculture-Bamidgeh, 2010 - The Society of Israeli Aquaculture and Marine Biotechnology (SIAMB)Juvenile Hippocampus barbouri were grown in illuminated cages with or without supplemental daytime feeding of thawed Acetes (a planktonic marine crustacean), or in non-illuminated cages with Acetes feeding, as a supplement to light-attracted zooplankton prey. After ten weeks, seahorses in illuminated cages fed Acetes had the highest mean body weight (2.24 g) and length (8.20 cm), but these did not significantly differ from seahorses in unfed illuminated cages (1.88 g; 7.25 cm), which did not significantly differ from those in fed non-illuminated cages (0.88 g; 6.32 cm). In all treatments, the mean instantaneous growth rate in body weight declined progressively throughout the test but the instantaneous growth rate in stretched length did not vary. Mean survival (76-100%) of seahorses in fed non-illuminated cages and in unfed illuminated cages did not vary significantly over the test period. The mean survival of seahorses in fed illuminated cages was lowest (54%), but did not significantly differ from the other treatments. Juvenile H. barbouri grown in illuminated cages had better growth than those in non-illuminated cages, but survival was reduced when seahorses in illuminated cages were fed Acetes.
Diet composition and feeding periodicity of the seahorse Hippocampus barbouri reared in illuminated sea cages -
Aquaculture, 2012 - ElsevierThe zooplankton prey composition and feeding periodicity of juvenile and adult seahorses Hippocampus barbouri reared in illuminated and non-illuminated sea cages were compared. Mean frequency of occurrence (%FO), prey composition (%N), and gut fullness of seahorses were calculated from analyses of gut contents. Compared with juvenile seahorses, adults consumed more variety of prey consisting of copepods, larvae of decapods, polychaetes and fish, and euphausid shrimps. Calanoid copedods were found in the gut of more juvenile (%FO = 47) and adult (%FO = 64) seahorses in illuminated cages but harpacticoid copepods were ingested by more juvenile fish (%FO = 50) in non-illuminated cages. Decapod larvae (%N = 66) in illuminated cages dominated the diet of juvenile seahorses, whereas in non-illuminated cages harpacticoid copepods (%N = 59) did. Calanoid copepods and decapod larvae (%N = 91–97) comprised the bulk of ingested prey among adult seahorses in all experimental cages. The gut of caged seahorses was generally full during daytime but declined in the evening, becoming almost empty at midnight, particularly among juveniles. Cage illumination commencing at midnight increased the number of filled guts at dawn (0400 h) among juvenile and adult seahorses. Unlike adult seahorses over a 24-h period, the overall incidence of filled guts among juveniles was not different between those in non-illuminated and illuminated cages. These results provide an alternative to growing caged H. barbouri on cultured live food, particularly copepods attracted by night illumination.