Skeletal Anomaly Monitoring in Rainbow Trout (Oncorhynchus mykiss, Walbaum 1792) Reared under Different Conditions

Abstract

The incidence of skeletal anomalies could be used as an indicator of the “quality” of rearing conditions as these anomalies are thought to result from the inability of homeostatic mechanisms to compensate for environmentally-induced stress and/or altered genetic factors. Identification of rearing conditions that lower the rate of anomalies can be an important step toward profitable aquaculture as malformed market-size fish have to be discarded, thus reducing fish farmers’ profits. In this study, the occurrence of skeletal anomalies in adult rainbow trout grown under intensive and organic conditions was monitored. As organic aquaculture animal production is in its early stages, organic broodstock is not available in sufficient quantities. Non-organic juveniles could, therefore, be used for on-growing purposes in organic aquaculture production cycle. Thus, the adult fish analysed in this study experienced intensive conditions during juvenile rearing. Significant differences in the pattern of anomalies were detected between organically and intensively-ongrown specimens, although the occurrence of severe, commercially important anomalies, affecting 2–12.5% of individuals, was comparable in the two systems. Thus, organic aquaculture needs to be improved in order to significantly reduce the incidence of severe anomalies in rainbow trout.

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

“…Harvest Chinook salmon deformity rates are high compared with rates from radiologic studies of cultured Atlantic salmon (e.g. Witten et al., ; 12%; 2007, Fjelldal et al., ; 12%; rainbow trout Oncorhynchus mykiss : Boglione et al., ; 2%–12%). Early workers reported lower deformity rates in wild adult Pacific salmonids, sockeye ( Oncorhynchus nerka ), pink ( Oncorhynchus gorbuscha ) and chum salmon ( Oncorhynchus keta ) with deformity prevalences of 2.8%, 3.3% and 2.9%, respectively (Gill & Fisk, ).…”

“…Spinal curvature (LKS) was rare at grading (2 fish of 432, 0.5%) but increased to 29.4% at harvest, some 9 months later. Incidence of LKS later in the production cycle is not significant in farmed Atlantic salmon (Fjelldal, Hansen, Breck et al., ) or rainbow trout (Boglione et al., ). This is a major difference between farmed Chinook salmon in New Zealand and other salmonids of both Salmo and Oncorhynchys spp.…”

Vertebrae length and ultra-structure measurements of collagen fibrils and mineral content in the vertebrae of lordotic gilthead seabreams (Sparus aurata)

“…The development of these skeletal deformities is not well understood and may be related to nutritional, environmental and genetic factors (Fernández et al, 2008;Boglione et al, 2014). Many researchers have proposed a variety of abiotic factors, such as environmental temperature, high swimming activity, photoperiod, tank colour, water temperature (Tandler et al, 1995;Kihara et al, 2002;Trotter et al, 2003;Sfakianakis et al, 2006;Cobcroft and Battaglene, 2009;Georgakopoulou et al, 2010;Prestinicola et al, the skeletal deformities downgrade the biological performance of the reared fish and the image of the final product, both negatively affecting the production cost and the market value (Divanach et al, 1996;Boglione et al, 2014). A 50% reduction of skeletal anomalies could save European aquaculture D 25,000,000 per year, while the estimated minimum annual loss due to skeletal anomalies is more than D 50,000,000 (Hough, 2009;Boglione et al, 2013a).…”

Morphology of the epaxial musculature and osteological development of the early developmental stages of softmouth trout (Salmothymus obtusirostris, Heckel, 1851)

“…Fish-like trout cannot swim efficiently with spinal deformities so they have greater risk from predators and are less capable of taking food (SILVESTRONE and HAMMELL, 2002). Farm fish are affected by skeletal malformations with the incidence depending on the species and developmental stage (BOGLIONE et al, 2014). In all investigated S. obtusirostris we did not notice any skeletal malformations.…”

“…A great deal of fish cultured products come from salmonid farms (BOGLIONE et al, 2014) and studies of muscle growth are therefore important for the future development of fish farming. Fish muscles are known to be suitable for study because they are not distinctly separated, as is the case with the muscles of higher vertebrates.…”