Comparison of diet composition, feeding, growth and health of lumpfish ( Cyclopterus lumpus L.) fed either feed blocks or pelleted commercial feed

Abstract

Two duplicate groups of individually tagged lumpfish (mean initial weight: 21.5 ± 3.2 g) were fed either a commercially available lumpfish feed or feed blocks for a period of 123 days. The aim was to evaluate and compare the effects of these feed types on growth, cataract development and histopathology in lumpfish. There were significant differences in growth rates between the groups with fish fed pelleted feed having the highest growth rates. The development of cataracts was significantly different with fish fed pelleted feed having a cataract prevalence of 87% at the end of the study period whilst fish fed with feed blocks had 10% prevalence. The results of the histological examination undertaken in this study showed overall small differences between the two dietary treatments. In some individuals in groups receiving both diets, there was mild to moderate expansion of the lamina propria with tissue most likely to represent fibrous tissue with scattered leucocytes. Overall, the findings of the present study show that lumpfish will readily graze from feed blocks and although growth is lower the prevalence of cataract is greatly reduced using feed blocks. K E Y W O R D Scataract, feed blocks, feeding, growth, lumpfish | 1953 IMSLAND et AL.

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

“…The aetiology of the ocular changes of farmed lumpfish described herein is still not completely understood despite the recent progress in decreasing the incidence and severity of cataract in young adults using different feed and rearing conditions (Imsland et al, ). One other possible cause is genetic anomalies inherent in the lumpfish populations in which it occurs.…”

“…The fact that the cataracts in lumpfish are mostly bilateral suggests the involvement of systemic factors. While the levels of N‐acetyl histidine in the lens could play a role in maintaining osmotic balance and preventing oxidative stress (Remø et al, ; Rhodes et al, ), the impact of this metabolite alone on cataract development in lumpfish does not appear to be as significant as it is in salmon (Imsland et al, , ; Jonassen et al, ). Likely, more than one dietary factor is involved in the development of cataract in lumpfish (Imsland et al, , ; 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, ). A diet with 35% less fat, 11% less protein and 40% less vitamin C but 23% more carbohydrate significantly reduced the incidence and severity of cataract development in cultured young adult lumpfish.…”

“…cataract, Cyclopterus lumpus L, histology, imaging, ocular pathology lumpfish has been recently shown to be largely influenced by diet (Imsland et al, 2019). A diet with 35% less fat, 11% less protein and 40% less vitamin C but 23% more carbohydrate significantly reduced the incidence and severity of cataract development in cultured young adult lumpfish.…”

Addressing the welfare needs of farmed lumpfish: Knowledge gaps, challenges and solutions

“…The main opportunities lay in reusing lumpfish at the end of the salmon cycle, although this may be limited by size constraints and concerns about transmitting diseases from one salmon cycle to the next, 32,54,98 closing the breeding cycle of the species in captivity and optimising rearing conditions. Other opportunities lay in increasing survival, welfare and delousing efficacy through selective breeding, 49,72 the development of improved diets 79,81 and food delivery systems, 67,96 as well as better disease management strategies. 13 In this sense, recent advances in non-destructive tissue sampling through laparoscopy and real-time PCR assays for rapid disease screening 86 should improve disease management.…”