Vertebral abnormalities in free-living Chinook salmon (Oncorhynchus tshawytscha, Walbaum) in New Zealand

• Published in: New Zealand Journal of Marine and Freshwater Research
• Main Authors: Davie, Peter S., Walker, Seumas P., Perrott, Matthew R., Symonds, Jane E., Preece, Mark, De Clercq, Adelbert, Munday, John S.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2018
• Subjects: Biology and Life Sciences; Spinal abnormalities; vertebra; free-living Chinook salmon; New Zealand; Oncorhynchus tshawytscha; FARMED ATLANTIC SALMON; EUROPEAN FISH LARVAE; EARLY SEAWATER PHASE; SALAR L; SPAWNING MIGRATION; ANADROMOUS MIGRATION; SKELETAL ANOMALIES; DEFORMITIES; GROWTH; DEMINERALIZATION; Atlantic salmon
• Online Access: https://biblio.ugent.be/publication/8671338; http://hdl.handle.net/1854/LU-8671338; https://doi.org/10.1080/00288330.2018.1455717

Spinal abnormalities are common in farmed Chinook Salmon in New Zealand. We report spinal abnormalities in adult Chinook salmon which were predominantly hatchery reared and released as smolts and which we term free-living. We compare these to rates seen in farmed New Zealand salmon. 101 free-living adult salmon were radiographically assessed for spinal curvatures (lordosis, kyphosis, scoliosis; LKS) and other vertebral abnormalities. Severity of abnormality was assessed on a three-point scale. Abnormal vertebral bodies were detected in 88.1% of free-living salmon. Spinal curvatures were the most common abnormality type with 83.2% of fish showing this abnormality but only one free-living Chinook had LKS of severity greater than 1. Farmed Chinook salmon are reported to have LKS rates of 29% with 18% of LKS abnormalities of severity greater than 1. These results suggest that free-living Chinook salmon frequently develop spinal abnormalities, but these abnormalities are less severe than those observed in farmed salmon.