Survival and distribution of pond- and hatchery-reared 0+ brown trout, Salmo trutta L., released in a Swedish stream

Abstract

During 1985-88, a tola! of 17500 under-yearling (0+) brown trout. 5a/mo/ru/W L., were released in Laktabacken Creek in Swedish Lapland. Of these, 15500 had been reared in a pond adjacent to the creek during their first summer, where they fed on natural prey. The other 2000 were conventionally reared hatchery fish fed dry food pellets. All fish were released in the autumn (size 6O-70mm) at the confluence of the pond outlet and the creek. Electrofishing revealed that the stocked fish gradually spread downstream from the point of release at the expense of the resident wild trout population. In 1989, stocked fish accounted for 70-90% and 30-50% of the trout population in the upper and lower stretches of the creek respectively. No long-term changes in total trout densities or standing crop occurred as a result of stocking.First-year survival of fish released in the creek varied between 15 and 30% over the 4 years. After 3 years, 5% of the slocked fish remained in the creek. Planted fish grew less rapidly than wild fish during the first year in the creek. Pond fish had a highersurvival rate than hatchery fish and showed a greater propensity to disperse from the point of release.

Recapture and condition of pond-reared, and hatchery-reared 1 + European grayling stocked in addition to wild conspecifics in a small river

“…In the present study, the differences in initial weight among wild and reared fish can be explained by lack of natural prey in hatchery fish and/or higher rearing density in artificially reared fish. The influence of rearing method (pond vs. hatchery) on recapture rates of artificially reared fish in this experiment is consistent with some published results (Huet, 1986;Näslund, 1992;Carlstein, 1997). In contrast, Johnsen and Hesthagen (1990) reported that the rearing method is not critical to the recapture rate of stocked brown trout.…”

“…Carlstein (1997) found that T. thymallus reared in a natural pond showed higher post-stocking survival in a lake than fish reared in a conventional hatchery. Näslund (1992) observed higher post-stocking survival in pond-reared brown trout compared to hatchery-reared. Johnsen and Ugedal (1986), however, found no longterm differences in post-stocking feeding of hatchery-reared and wild brown trout.…”

Habitat Use by Native and Stocked Trout (Salmo Trutta L.) in Two Northeast Streams, Portugal

“…Given the movement exhibited by the captured trout it is possible that most of the individuals travelled long distances in a downstream direction just one month after their release. The post-stocking movement of salmonids has already been reported in several studies (CRESSWELL, 1981;MORING, 1993;JONSSON et al, 1999), although contradictory results have also been obtained (HEGGENES, 1988;NASLUND, 1998). Additionally, the high vulnerability of stocked fish to predation (JACOBSEN, 2005), which is present in both streams, namely by otters (Lutra lutra), coupled with the possible decline of fish condition during their adaptation to habitat and available food resources may have been responsible for the decrease of stocked trout.…”

Re‐building brown trout populations in dredged boreal forest streams: in‐stream restoration combined with stocking of young trout

“…The supplemental stocking included in our study seemed to resurrect the densities of brown trout age-classes older than the stocked fish in the streams undergoing management (see also Jutila, Karttunen & Niemitalo, 1994), although this trend was not consistently observed in post-management streams. Further, Jutila et al (1994) and Näslund (1998) showed that the survival of stocked 1+ and 2+ aged brown trout was relatively high the first summer after the stocking, but decreased during winter. Jokikokko (1990) reported that brown trout disappeared almost completely within 2 years after fry stocking was terminated, because of the lack of natural reproduction in the rapids of the restored timber floating streams in eastern Finland.…”