Density-Dependent Compensatory Growth in Brown Trout (Salmo trutta) in Nature

Abstract

Density-dependence is a major ecological mechanism that is known to limit individual growth. To examine if compensatory growth (unusually rapid growth following a period of imposed slow growth) in nature is density-dependent, one-year-old brown trout (Salmo trutta L.) were first starved in the laboratory, and then released back into their natural stream, either at natural or at experimentally increased population density. The experimental trout were captured three times over a one-year period. We found no differences in growth, within the first month after release (May-June), between the starved fish and the control group (i.e. no evidence of compensation). During the summer however (July-September), the starved fish grew more than the control group (i.e. compensation), and the starved fish released into the stream at a higher density, grew less than those released at a natural density, both in terms of weight and length (i.e. density-dependent compensation). Over the winter (October-April), there were no effects of either starvation or density on weight and length growth. After the winter, starved fish released at either density had caught up with control fish in body size, but recapture rates (proxy for survival) did not indicate any costs of compensation. Our results suggest that compensatory growth in nature can be density-dependent. Thus, this is the first study to demonstrate the presence of ecological restrictions on the compensatory growth response in free-ranging animals.

State-dependent behavior and alternative behavioral strategies in brown trout (Salmo trutta L.) fry

“…However, the above-stated general predictions regarding low-asset individuals apply to LL and HL, in relation to HH. Compensatory growth, predicted for LH, has been observed repeatedly in older juveniles of brown trout from the same population as used in this study (Johnsson and Bohlin 2006; Sundström et al 2013; Näslund et al 2015). Alternatively, SDS resulting from increased size may result in a general tendency for trout fry to maximize activity, neophobia, and aggression regardless of energetic state.…”

A Stock-Recruitment Relationship Applicable to Pacific Bluefin Tuna and the Pacific Stock of Japanese Sardine

“…The Ricker [2], Beverton and Holt [3] or hockey stick [4] model has been used as a typical SRR model in fisheries sciences. A huge number of papers related to SRR have been published; however, almost all papers have been discussed based on the assumption that a density-dependent effect really exists [5]- [8].…”

Autumn food restriction reduces smoltification rate, but not over‐winter survival, in juvenile brown trout Salmo trutta

“…If food is restricted or withheld in spring, salmonid fish tend to respond with compensatory growth, that is, faster than normal increase in body size, to catch up in size when food becomes available (Johnsson & Bohlin , ; Sundström et al. ; Näslund et al. ).…”

“…If food is restricted or withheld in spring, salmonid fish tend to respond with compensatory growth, that is, faster than normal increase in body size, to catch up in size when food becomes available (Johnsson & Bohlin 2005Sundstr€ om et al 2013;N€ aslund et al 2015b). However, the compensatory response often declines in autumn, and in winter the growth rate converges with that of individuals not being food-restricted, regardless of whether they have caught up in size or not (Johnsson & Bohlin 2005;N€ aslund et al 2015b).…”