The effect of water temperature on vertebral deformities and vaccine-induced abdominal lesions in Atlantic salmon, Salmo salar L.

Abstract

This study investigates the effects of water temperature (T) on vaccine-induced abdominal lesions (i.p. injection with oil-adjuvant vaccine) and vertebral deformities in Atlantic salmon. Quadruple groups of vaccinated (V) or unvaccinated (U) underyearling smolts were reared in tanks under four different temperature regimes for 6 weeks in fresh water (FW) followed by 6 weeks in sea water (SW). The four different T regimes were 10 °C FW-10 °C SW (10-10), 10 °C FW-16 °C SW (10-16), 16 °C FW-10 °C SW (16-10) and 16 °C FW-16 °C SW (16-16). After the temperature regimes were finished, the fish were group-tagged and transferred to a common sea cage for on-growth until harvest size. At termination, weight was significantly affected by both T and V, while lesion score and deformities were affected by T only. The weight difference between the largest and smallest U group was 20.3% (16-10 U: 2.4 kg, 10-16 U: 1.89 kg), while the largest difference between U and V fish within a T regime was 28.7% (16-16 U: 2.1 kg, 16-16 V: 1.5 kg). Fish from the 16-16, 16-10 and 10-16 regimes had a significant higher lesion score than those from the 10-10 regime. Fish from the 10-16 and 16-16 regimes displayed a significantly higher prevalence of vertebral deformities (palpation : 13-27%, radiology: 88-94%) than fish from the 10-10 and 16-10 regimes (palpation: 2-3%, radiology: 27-65%). Vertebra number 26 (located beneath the dorsal fin) was the most frequently affected vertebra in smolts, while vertebra number 43 (located above the anal fin) was most frequently affected in adults.

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

“…() took care to note every deformity and reported vertebral deformities of 33%–50% in wild Atlantic salmon. We note that prevalence can be highly variable and range from near zero up to 92% (Fjelldal, van der Meeren, Jørstad, & Hansen, ; Fjelldal et al., ; Fjelldal, Hansen, Breck et al., ; Grini, Hansen, Berg, Wargelius, & Fjelldal, ; Korsøen, Dempster, Fjelldal, Oppedal, & Kristiansen, ; Taylor et al., ; Witten et al., ). Why such a large range of prevalence is reported may relate to the wide range of potential causes of vertebral deformities (see Boglione, Gisbert et al., for review) and variations in assessment techniques and criteria.…”

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

“…In farmed Atlantic salmon, deformities that occur in the posterior trunk region below the dorsal fin, typically develop in freshwater (Sullivan et al., 2007a; Fjelldal and Hansen, 2010; Grini et al., 2011). In contrast, deformities that are located in the anterior caudal region, typically develop in seawater (Fjelldal et al., 2009a; Grini et al., 2011). Heat shock during egg incubation can induce caudal vertebral body deformities early in development (Wargelius et al., 2005).…”

“…Such deformities surface at the parr stage, in animals of 10 cm fork length, as distinct fusion centra (Wargelius et al., 2005). Caudal vertebral body deformities that develop in seawater will usually appear as compressions in harvest size fish (Fjelldal et al., 2009a; Grini et al., 2011). In addition, deformities sometimes develop post cranial (Fjelldal et al., 2007a, 2009b, 2010; Sullivan et al., 2007a).…”

The effect of low temperatures and photoperiods on growth and vertebra morphometry in Atlantic salmon

“…The observed values on vertebra standardized dorsoventral diameter (DDs) are within normal values for postsmolts (Fjelldal et al 2005(Fjelldal et al , 2009) and do not suggest pathological changes. Accordingly, Grini et al (2011) found that postsmolts at 16°C developed vertebra deformities, while postsmolts at 10°C did not. Why LL stimulated the vertebra to grow more in length than in diameter and resulted in LL fish having more slender vertebrae is not clear.…”