A possible relation between growth and number of deformed vertebrae in Atlantic salmon (Salmo salarL.)

Abstract

The aim of the present study was to elucidate whether vertebral deformities influence on the growth performance of salmon, and if so, at what level of severity the growth performance ⁄ welfare is affected. To do this, Atlantic salmon postsmolts were individually tagged and reared in a common seacage from January 2005 until January 2006. At the end of the experiment, dissected vertebral columns were radiographed, evaluated for vertebral deformities, and the location and type of deformity was recorded. For statistical analysis the fish were grouped according to the number of deformed (d) vertebrae (v); 0 dv (n = 173), 1-5 dv (n = 43), 6-10 dv (n = 11), 11-20 dv (n = 18) and 21-44 dv (n = 31). In fish with less than six dv, the deformities were found within the tail fin region (v 50-58). Fish with 11-20 dv also had a high occurrence of dv within the tail region (V31-49), and fish with more than 20 dv also had a high occurrence of dv within the caudal trunk region (V9-30). Growth was significantly influenced by the number of dv. At the end of the experiment, fish with more than 10 dv were shorter and had a higher condition factor than normal fish, and fish with more than 20 dv were shorter, had lower weight and a higher condition factor than normal fish. In the first period in seawater (January-June) there was no detectable differences in growth (length or weight) between the groups, but the condition factor of the individuals with a high number of dv increased. In the second period (June-January), fish with more than 10 dv, had a significantly lower growth rate. This study indicate that a low occurrence of vertebral deformities have little effect on the growth performance ⁄ welfare of salmon.

Spinal curvatures and onset of vertebral deformities in farmed Chinook salmon, Oncorhynchus tshawytscha (Walbaum, 1792) in New Zealand

“…Deformity onset leads to slower growth and may act through ‘fitness’; this is similar to the findings of Hansen et al. (), who reported that early growth of Atlantic salmon to around 500 g was unaffected by vertebral deformity status. Whether or not the early growth rate of fish post‐seawater entry influenced late onset deformity remains to be established.…”

“…While Hansen et al. () reported early growth of Atlantic salmon to be unaffected by vertebral deformity, growth from around 500 g onwards to harvest size (around 4 kg) was significantly lower in deformed fish and that fish with more deformed vertebrae (= high severity) were the slowest growing. Thus, we agree with Fjelldal et al.…”

“…() and Hansen et al. (), who reported that while heavily deformed fish (visibly deformed or high severity) grew slowly as they neared harvest size, the relationship between growth and deformity was weak earlier in the production cycle.…”

Vertebral deformities in farmed Atlantic salmon (Salmo salar L.) - etiology and pathology

“…Post cranial deformities have been reported to occur in both juveniles (Sullivan et al., 2007a) and adults (Fjelldal et al., 2009b, 2010), and can be induced during the parr stage (Fjelldal et al., 2007a). Other deformities occur in the ural region (Berg et al., 2006; Fjelldal et al., 2010; Hansen et al., 2010) including the urostyle (Fjelldal et al., 2006, 2009b). Ural region deformities are mostly observed in adults (Berg et al., 2006; Hansen et al., 2010), whereas urostyle deformities occur in smolts (Fjelldal et al., 2006) and in adults (Fjelldal et al., 2009b).…”

Unilateral perivertebral fibrosis associated with lordosis, kyphosis and scoliosis (LKS) in farmed Chinook salmon in New Zealand

“…In farmed Atlantic salmon, deformities have been detected by visible examination and palpation in around a quarter of fish at harvest and in up to 70% of fish by radiography (Fjelldal et al 2012b). Spinal deformities have been reported to result in slower growth and reduced harvest weights (Hansen et al 2010). Additionally, the presence of severe deformities can also reduce the value of the fish due to difficulties during processing and the presence of increased connective tissue in fillets from affected fish (Haugarvoll et al 2010).…”