Prevalence of spinal abnormalities in Chinook salmon smolt and influence of early rearing temperature and growth rates

Abstract

Spinal abnormalities can be detected at harvest in around 40% of farmed Chinook salmon in New Zealand. However, whether these abnormalities are present in smolt is unknown. Radiographs of 3,736 smolt were taken immediately prior to transfer to sea water and evaluated for fusions, compressions, vertical shifts, and lordosis, kyphosis and/or scoliosis (LKS). The survey included smolt from two different chilling strategies that had been graded into slow- or fast-growing fish. Overall, 4.34% of Chinook salmon smolt had at least one spinal abnormality, similar to the rates of reported in Atlantic salmon smolt. The rate of abnormality was significantly higher in faster-growing fish. Fusions were most common with 2.68% of smolt affected. Smolt subjected to longer chilling times had lower rates of fusions. Compressions and vertical shifts were both observed in 1.31% of smolt. Although LKS is the most common abnormality of harvested fish, LKS was detected in just five smolt. The results suggest that some fusions in harvest fish have developed at the time of seawater transfer while LKS develops late in the production cycle. Overall, spinal abnormalities are uncommon in Chinook salmon smolt and may be influenced by chilling times and growth rates.

Temperature Significantly Regulates Gene Expressions of Vertebrae Chondrocytes and Osteoblasts in Juvenile Golden Pompano (Trachinotus ovatus)

“…Existing research suggests that transformation, remodeling, and replacement of intervertebral tissue eventually lead to vertebral fusion, which involves alterations in extracellular matrix (ECM) components, metaplastic chondrogenesis and mineralization (Witten et al, 2006;Pedersen et al, 2011;Davie et al, 2019). Meanwhile, the occurrence of vertebral fusion is externally regulated by rearing temperature and nutritional factors (Ytteborg et al, 2010a;Wu et al, 2016;Munday et al, 2018).…”

Radiographic characterisation of spinal curvature development in farmed New Zealand Chinook salmon Oncorhynchus tshawytscha throughout seawater production

“…Deviations of the entire vertebral column, as in spinal curvatures, are comparatively rare. However, in Chinook (king) salmon ( Oncorhynchus tshawytscha ) farmed in New Zealand (NZ), spinal curvatures in the form of lordosis (downwards), kyphosis (upwards) and scoliosis (lateral) comprise the majority of spinal aberrations 20 – 23 , and can affect up to 40% of individuals at harvest 24 . The curvatures are known to appear late in production, in the last nine months of the seawater cycle 23 , but their exact point of onset, and thus the critical seawater period(s) for their development, remains to be identified.…”

“…The curvatures are known to appear late in production, in the last nine months of the seawater cycle 23 , but their exact point of onset, and thus the critical seawater period(s) for their development, remains to be identified. Spinal curvatures are also known to develop in the early hatchery stages of Chinook salmon production 25 , but these anomalies are rare in smolts 24 , suggesting that curvatures which appear later during seawater production may arise by different mechanisms. Although termed “LKS” (lordosis–kyphosis–scoliosis), the three curvature types can develop in isolation or in various combinations within an individual.…”

Identification of Loci Controlling the Dwarfism Trait in the White Sailfin Molly (Poecilia latipinna) Using Genome-Wide Association Studies Based on Genotyping-By-Sequencing

“…Spinal deformities are a frequent phenomenon in many different fish species and can be caused by many factors during fish development, such as bacterial and parasitic infections, water environment, elevated egg incubation temperatures, pollution, nutrients, inappropriate light regimes and vaccination, etc. [2,3,4,5,6,7]. Spinal deformities often result in increased metabolic costs in the deformed fish, leading to reduced growth and low harvest weight [8].…”