Comparison of Life History Traits between First‐Generation Hatchery and Wild Upper Yakima River Spring Chinook Salmon

Abstract

Abstract.-Life history traits in hatchery and wild spring Chinook salmon Oncorhynchus tshawytscha from the upper Yakima River were compared to determine whether locally adapted traits had diverged after one generation of state-of-the-art artificial propagation. Sex composition in wild-and hatchery-origin fish differed in three of four brood years (P 0.01). The proportion of hatchery males, primarily age 3, increased from 38% to 49% over time. Conversely, the sex composition of wild fish did not exhibit a similar linear trend. Most hatchery-and wild-origin fish reached maturity at age 4 (!76%), followed in magnitude by ages 3 and 5. Wild mean age at maturation demonstrated no significant trend over time, while hatchery mean age at maturation declined (P ¼ 0.05). Mean lengths of 3-5-year-old hatchery fish were shorter than those of wild fish of the same age (differences of 2.7 cm for age 3, 1.7 cm for age 4, and 1.9 cm for age 5). Likewise, body weights of hatchery fish were lower than those of wild fish (differences of 0.3 kg for age 3, 0.3 kg for age 4, and 0.6 kg for age 5), representing a change in body size of between 0.5 and 1.0 standard deviation (SD). Median arrival timing of hatchery and wild fish at a broodstock collection site just downstream of ancestral spawning grounds showed no consistent difference. However, the median arrival date of age-3 fish was 19-20 d later than that for fish of ages 4 and 5 (P , 0.01). Mean spawn timing of hatchery fish was significantly earlier (5.1 d) than that of wild fish in a ''common-garden'' experiment (P , 0.05). We estimate that fitness could be reduced by as much as 1-5% for traits diverging from their optima by 0.5-1.0 SD. The degree of genetic determination of the divergence is unknown, but future monitoring will help clarify this. Perhaps the most important conclusion of our study is that even a hatchery program designed to minimize differences between hatchery and wild fish did not produce fish that were identical to wild fish.

Monitoring the Reproductive Success of Naturally Spawning Hatchery and Natural Spring Chinook Salmon in the Wenatchee River, 2008-2009 Progress Report.

“…Indeed, if age structure were not taken into account in the analysis, hatchery males would have a relative fitness of only 0.25 in 2004, when most adult hatchery males were three-year-olds and most wild males were four-year-olds (Table 3). Hatchery fish have a tendency to mature at earlier ages than wild fish (Knudsen et al 2006;Murdoch et al 2008), but the difference is subtle and does not explain the differences in age structure in 2004 and 2005. Instead, these differences were due mostly to an increase in hatchery releases starting in 2003, and the three-year-olds that returned to spawn in 2004 were in high abundance due to this strong hatchery cohort (Murdoch, unpublished data).…”

“…Differences in breeding success or fitness between hatchery and natural origin salmonids has been linked to genetics effects resulting from domestication selection in the hatchery environment Currens 1995, Lynch and. Domestication selection can manifest as differences in morphological Knudsen et al 2006;Busack et al 2007) and behavioral ) traits between hatchery and naturally produced fish. Understanding how these differences influence the fitness of hatchery fish in the natural environment would assist in the modification of hatchery practices or programs intended to conserve or rebuild populations.…”

“…Because hatchery fish may return as adults at an earlier age or smaller size (Knudsen et al 2006), knowledge of female size constructing a redd would control for any size-related differences in order to determine if any differences in redd structure or spawning site habitat existed between hatchery and naturally produced fish. Our objectives of this study were to 1) describe spawning site and redd characteristics of spring Chinook salmon in the selected reaches; 2) compare spawning site and redd habitat characteristics of hatchery and naturally produced female spring Chinook and 3) explore possible relationships between female size (fork length and weight) and any spawning site and redd characteristics.…”

Structure of run, abundance and biological characteristics of hatchery and wild chum salmon in the basin of the Paratunka River (southeastern Kamchatka) in 2010-2015

“…Омоложение производителей заводской кеты отмечали и другие исследователи (Лысенко, Шабельский, 2002; Рослый, 2002; Горяинов и др., 2012; Иванков, Иванкова, 2015). Известно, что и другие виды заводских лососей созревают раньше диких и воз-вращаются более мелкими (Heath et al, 1994;Daugherty et al, 2003;Knudsen et al, 2006;Запорожец, Запорожец, 2011а;Запорожец и др., 2012).…”

Life history effects on hatchery contributions to ocean harvest and natural-area spawning

“…There are documented life history differences between hatcheryand natural-origin fish, including size and age distributions (e.g., Swain et al 1991;Knudsen et al 2006;Vainikka et al 2010), reproductive traits (e.g., Fleming and Gross 1993;Quinn 1993), survival and growth (e.g., Jonsson et al 2003;see Naish et al (2008) for a review of hatchery life history effects). Many studies track hatcheryorigin proportions in fisheries harvest (e.g., Zaugg et al 1983;Hilborn and Eggers 2000;Barnett-Johnson et al 2007) and among natural-area spawners (e.g., Seelbach and Whelan 1988;Kostow et al 2003;Nickelson 2003).…”