Water temperature and dietary histidine affect cataract formation in Atlantic salmon (Salmo salar L.) diploid and triploid yearling smolt

Abstract

The aim of the present study was to investigate cataract development in diploid (2N) and triploid (3N) Atlantic salmon smolts and post-smolts at two water temperatures (10 and 16°C) given diets with different histidine supplementation (LH, 10.4 and HH, 13.1 g kg À1 ) before and after seawater transfer. In freshwater, a severe cataract outbreak was recorded in both ploidies reared at 16°C. The cataract score was significantly higher in triploids compared to diploids, and the severity was lower in both ploidies fed the HH diet. The cataract development at 10°C was minor. Low gill Na + , K + -ATPase activity in fish reared at 16°C before seawater transfer was followed by osmoregulatory stress with elevated plasma electrolyte concentrations and high mortality in sea water. Both diploids and triploids reared at 10°C developed cataracts during the seawater period, with higher severities in triploids than diploids and a reduced severity in the fish fed the HH diet. The findings of this study demonstrate the importance of environmental conditions in the husbandry of Atlantic salmon, and particularly triploids, with regard to smoltification and adjusted diets to mitigate cataract development in fresh and sea water.

Changes in water temperature and oxygen: the effect of triploidy on performance and metabolism in large farmed Atlantic salmon

“…2015, Fjelldal et al 2016, Smedley et al 2016. The reasons for this may be multifactorial and can include weight loss due to smoltification (Sambraus et al 2017b) or, as observed in the present study, increasing length growth when weight growth is stagnating or de creasing. Nevertheless, the present data on feed intake, growth rate and condition factor show that triploids can outgrow diploid Atlantic salmon at cold and moderate water temperatures.…”

“…Another concern with triploid salmon are higher incidences of ocular cataracts compared to diploids (Wall & Richards 1992, Taylor et al 2015, Sambraus et al 2017b. The pathology of this disorder in diploid salmon becomes more severe at high (Waagbø et al 2010) and fluctuating (Bjerkås & Bjørnestad 1999) water temperature as well as in periods of fast growth (Bjerkås et al 2001, Waagbø et al 2010.…”

“…In salmonids, as visual feeders, severe cataracts and poor vision may reduce welfare and feed intake, and limit affected fish in reaching their growth potential (Breck & Sveier 2001). Dietary histidine levels can mitigate cataract outbreaks in both ploidies, al though the requirement is higher in triploids than diploids (Taylor et al 2015, Sambraus et al 2017b. The positive affect of histidine is associated with its metabolite N-acetyl-histidine (NAH) that functions as an osmolyte (Rhodes et al 2010) and potentially an antioxidant (Remø et al 2011) in the lens.…”

Ocular tissue changes associated with anterior segment opacity in lumpfish (Cyclopterus lumpus L) eye

“…Identified causes of cataract development in Atlantic salmon and rainbow trout include environmental factors (e.g. water quality, temperature) and nutritional imbalances, some of which have been linked to osmotic imbalance and oxidative stress correlating to lower levels of N-acetyl histidine (Bjerkås et al, 2006;Remø et al, 2017Remø et al, , 2011Rhodes, Breck, Waagbø, Bjerkås, & Sanderson, 2010;Sambraus et al, 2017;Waagbø et al, 2010). The fact that the cataracts in lumpfish are mostly bilateral suggests the involvement of systemic factors.…”

“…Cataract severity was shown to increase with prevalence and fish weight (Jonassen et al, ). Previous studies have attributed the development of cataract in farmed teleost such as Atlantic salmon and rainbow trout ( Oncorhynchus mykiss ) to dietary deficiencies of N‐acetyl histidine as well as environmental conditions (Bjerkås, Breck, & Waagbø, ; Remø, Hevrøy, Breck, Olsvik, & Waagbø, ; Sambraus et al, ; Waagbø, Trösse, Koppe, Fontanillas, & Breck, ). The incidence of cataract in juvenile and young adult cultured lumpfish has been recently shown to be largely influenced by diet (Imsland et al, ).…”