title: Accommodating the cost of growth and swimming in fish-the applicability of exercise-induced growth to juvenile hapuku (Polyprion oxygeneios).
abstract: Induced-swimming can improve the growth and feed conversion efficiency of finfish aquaculture species, such as salmonids and Seriola sp., but some species, such as Atlantic cod, show no or a negative productivity response to exercise. As a possible explanation for these species-specific differences, a recent hypothesis proposed that the applicability of exercise training, as well as the exercise regime for optimal growth gain (ERopt growth), was dependent upon the size of available aerobic metabolic scope (AMS). This study aimed to test this hypothesis by measuring the growth and swimming metabolism of hapuku, Polyprion oxygeneios, to different exercise regimes and then reconciling the metabolic costs of swimming and specific dynamic action (SDA) against AMS. Two 8-week growth trials were conducted with ERs of 0.0, 0.25, 0.5, 0.75, 1, and 1.5 body lengths per second (BL s(-1)). Fish in the first trial showed a modest 4.8% increase in SGR over static controls in the region 0.5-0.75 BL s(-1) whereas the fish in trial 2 showed no significant effect of ER on growth performance. Reconciling the SDA of hapuku with the metabolic costs of swimming showed that hapuku AMS is sufficient to support growth and swimming at all ERs. The current study therefore suggests that exercise-induced growth is independent of AMS and is driven by other factors.
authors.affiliation: Leigh Marine Laboratory, Institute of Marine Science, The University of Auckland Auckland, New Zealand.
authors.forename: Javed R
authors.initials: JR
authors.lastname: Khan
authors.affiliation: Bay of Plenty Polytechnic Tauranga, New Zealand.
authors.forename: Caroline
authors.initials: C
authors.lastname: Trembath
authors.affiliation: National Institute of Water and Atmospheric Research, Bream Bay Aquaculture Park Ruakaka, New Zealand.
authors.forename: Steve
authors.initials: S
authors.lastname: Pether
authors.affiliation: National Institute of Water and Atmospheric Research, Bream Bay Aquaculture Park Ruakaka, New Zealand.
authors.forename: Michael
authors.initials: M
authors.lastname: Bruce
authors.affiliation: National Institute of Water and Atmospheric Research, Bream Bay Aquaculture Park Ruakaka, New Zealand.
authors.forename: Seumas P
authors.initials: SP
authors.lastname: Walker
authors.affiliation: Leigh Marine Laboratory, Institute of Marine Science, The University of Auckland Auckland, New Zealand.
authors.forename: Neill A
authors.initials: NA
authors.lastname: Herbert
keywords: aerobic metabolic scope; cost of transport; exercise training; optimal swim speed; swim-flume respirometry