Single generation exposure to a captive diet: a primer for domestication selection in a salmonid fish?

Abstract

14Millions of wild animals in captivity are reared on diets that differ in their uptake and composition 15 from natural conditions. Few studies have investigated whether such novel diets elicit 16 unintentional domestication selection in captive rearing and supplementation programs. In highly 17 fecund salmonid fishes, natural and captive mortality is highest in the first few months of 18 exogenous feeding. This high early mortality might be a potent driver of unintentional selection 19 because wild fish normally forage on live prey whereas they are fed almost exclusively pellet feed 20 in captivity: fish that do not adapt pellet feed well under captive conditions experience reduced 21 growth and/or die. We tested this hypothesis by generating a large number of families from F1 22 captive and wild fish originating from the same three populations and then rearing them each on 23 pellet and natural, live, drifting feed for three months at the beginning of exogenous feeding. We 24 found that captive fish of every population grew faster than wild fish in all diet treatments. 25Populations exhibited an idiosyncratic response to diet treatment, with two populations exhibiting 26 faster growth on a pellet diet versus the natural diet but another population exhibiting similar 27 growth in both diet treatments. Fish exposed to a natural diet also exhibited higher survival relative 28 to those given a pellet diet. Captive and wild fish did not differ in survival, regardless of population 29 of origin. Overall, we found evidence that rapid domestication selection associated with a single 30 generation exposure to a novel captive diet generates genetically-based changes to individual 31 fitness (e.g., growth and survival) in a wild fish. 32 33

Does parental angling selection affect the behavior or metabolism of brown trout parr?

“…The hatchery environment is expected to favor individuals with a fast metabolic rate (Robertsen et al, 2019). However, because metabolic rate measurements can induce stress responses (Murray et al., 2017) and domestication‐related phenotypic changes can be evident in hatchery environments already after a single generation in salmonids (Christie et al., 2016; Islam et al., 2020), the result could be explained by a better ability of the hatchery‐population fish to adjust to handling during metabolic rate measurements. Further, metabolic rate might relate to the life‐history strategy of the fish (Rosenfeld et al., 2015), as the wild fish represented resident and the captive fish migratory brown trout forms (Lemopoulos et al., 2019).…”

Does parental angling selection affect the behavior or metabolism of brown trout parr?

“…The hatchery environment is expected to favor individuals with a fast metabolic rate (Reid et al 2012;Robertsen et al 2018). However, because metabolic rate measurements can induce stress responses (Murray et al 2017) and domestication-related phenotypic changes can be evident in hatchery environments already after a single generation in salmonids (Christie et al 2016, Islam et al 2020, the result could be explained by a better ability of the hatchery-population fish to adjust to handling during metabolic rate measurements. Further, metabolic rate might relate to the life-history strategy of the fish (Rosenfeld et al 2015), as the wild fish represented resident and the captive fish migratory brown trout forms (Lemopoulos et al 2019b).…”

Size, fecundity and condition factor changes in endangered delta smelt Hypomesus transpacificus over 10 generations in captivity

“…Live prey and/or dry feed were provided consistently to ensure that fish were not food limited, there were no predators or competitors, and water quality was always managed properly. Studies have shown that cultured fish grew significantly faster than their wild counterparts due to stable food availability and quality, higher consumption rates, less exercise and energy expenditure (Islam et al., 2020; Teletchea, 2019; Wringe et al., 2016). Other researchers have also shown that many other factors can influence fecundity, such as environmental conditions (Salvanes & Braithwaite, 2005), stress (Schreck et al., 2001), fish size (Kjesbu et al., 1996) and the duration of the spawning period (Bennett, 2005; Brown et al., 2013; Hunter et al., 1985).…”