Do swimming fish always grow fast? Investigating the magnitude and physiological basis of exercise-induced growth in juvenile New Zealand yellowtail kingfish, Seriola lalandi

Abstract

There is a wealth of evidence showing that a moderate level of non-stop exercise improves the growth and feed conversion of many active fishes. A diverse number of active fish are currently being farmed, and an optimal level of exercise may feasibly improve the production efficiency of these species in intensive culture systems. Our experiments have set out to resolve the growth benefits of juvenile New Zealand yellowtail kingfish (Seriola lalandi) enforced to swim in currents at various speeds over two temperatures (14.9 and 21.1 °C). We also probed potential sources of physiological efficiency in an attempt to resolve how growth is enhanced at a time of high energetic expenditure. Results show that long-term exercise yields a 10% increase in growth but this occurs in surprisingly low flows (0.75 BL s⁻¹) and only under favourable environmental temperatures (21.1 °C). Experiments using a swim flume respirometer indicate that exercise training has no effect on metabolic scope or critical swimming speeds but it does improve swimming efficiency (lower gross costs of transport, GCOT). Such efficiency may potentially help reconcile the costs of growth and exercise within the range of available metabolic energy (scope). With growth boosted in surprisingly low flows and elevated water temperatures only, further investigations are required to understand the bioenergetics and partitioning of costs in the New Zealand yellowtail kingfish.

Disrupted flow sensing impairs hydrodynamic performance and increases the metabolic cost of swimming in the yellowtail kingfish,Seriola lalandi

“…This measure of SMR is close to that of our control fish, but obviously applies to a smaller fish and is therefore less than that of our S. lalandi if a mass exponent of -0.2 is applied. The U opt of control and sham treated fish within the current line of work was 2.0FLs -1 at 18°C, which is directly comparable to 2.2FLs -1 U opt of S. lalandi at 22°C within the study of Brown et al (Brown et al, 2011) using the same swim flume and similarly sized fish. However, other more sluggish species such as saithe and whiting are seen to have much lower U opt values in the vicinity of 1.4 and 1.0FLs -1 , respectively (Steinhausen et al, 2005).…”

“…The respirometer ran with a single measurement cycle consisting of three periods (i.e. flushing, waiting and measuring) according to the protocol of Steinhausen et al (Steinhausen et al, 2005) and Brown et al (Brown et al, 2011). During the flushing period, the flushing pump was active to mix the water inside the respirometry flow chamber and to ensure proper flow past the oxygen sensor.…”

Swimming in air‐breathing fishes

“…This is because energy is expended on vertical as well as on horizontal movements, and because swimming near to or breaking the water surface increases drag (Hertel, 1966;Blake, 1983a;Videler, 1993) thus decreasing swimming performance (Webb et al, 1991). The cost of transport can be estimated from measurements of oxygen uptake at various aerobic swimming speeds (Claireaux et al, 2006;Fitzgibbon et al, 2007;Brown et al, 2011;Luna-Acosta et al, 2011). The net cost of swimming (C N ) for two air-breathing species, G. carapo and P .…”

Physiological Mechanism and Application of Fish Exercise Training in Aquaculture

“…In addition, the effects of exercise training on fish growth may be related to the culture environment, seasons the sizes of the fish, and so on [31][32][33][34].…”