Development of a Natural Rearing System to Improve Supplemental Fish Quality, 1999-2003 Progress Report.
The National Marine Fisheries Service (NMFS) has been conducting Natural Rearing Enhancement System (NATURES) research since the early 1990s. NATURES studies have looked at a variety of mechanisms to enhance production of wild-like salmonids from hatcheries. The goal of NATURES research is to develop fish culture techniques that enable hatcheries to produce salmon with more wild-like characteristics and increased postrelease survival. The development of such techniques is called for in the Columbia Basin Fish and Wildlife Program. This document is the draft report for the Supplemental Fish Quality Contract DE-AI79-91BP20651 Over the history of the project, the effects of seminatural raceway habitats, automated underwater feeders, exercise current velocities, live food diets, and predator avoidance training have been investigated. The findings of these studies are reported in an earlier contract report (Maynard et al. 1996a). The current report focuses on research that has been conducted between 1999 and 2002. This includes studies on the effect of exercise on salmon and steelhead trout, effects of predator avoid training, integration of NATUES protocols into production hatcheries, and the study of social behavior of steelhead grown in enriched and conventional environments. Traditionally, salmon (Oncorhynchus spp.) are reared in barren concrete raceways that lack natural substrate, in-stream structure, or overhead cover. The fish are fed in an unnatural manner with artificial feeds mechanically or hand broadcast across the water surface. This traditional approach has increased the egg-to-smolt survival of hatchery-reared fish by an order of magnitude over that experienced by wild-reared salmon. However, once hatchery-reared fish are released into the wild their smolt-to-adult survival is usually much lower than wild-reared salmon. The reduced postrelease survival of hatchery-reared fish may stem from differences in their behavior and morphology compared to wild-reared salmon. After release, hatchery-reared fish are inefficient foragers and are often found with empty stomachs or stomachs filled with indigestible debris (Miller 1953, Hochachka 1961, Reimers 1963, Sosiak et al. 1979, Myers 1980, O'Grady 1983, Johnsen and Ugedal 1986). Their social behavior also differs, with hatchery-reared fish congregating at higher densities, being more aggressive, and displaying less territory fidelity than wild-reared fish (Fenderson et al. 1968, Bachman 1984, Swain and Riddell 1990). In the natural environment this results in hatchery-reared fish spending more time in high-risk aggressive behavior and less time in beneficial foraging behavior than their wild-reared counterparts. Hatchery-reared fish are also more surface oriented than wild-reared salmonids (Mason et al. 1967, Sosiak 1978). This increases their risk of being attacked by avian predators, such as kingfishers (Ceryle spp.), which search for fish near the surface. Although some of the differences between wild and hatchery-reared fish are innate (Reisenbichler and McIntyre 1977, Swain and Riddell 1990), many are conditioned and can be modified by altering the hatchery rearing environment. NATURES studies are aimed at developing a more natural salmon culture environment to prevent the development of these unnatural attributes in hatchery-reared fish. NATURES fish culture practices are already producing salmon with up to about 50% higher in-stream survival than conventionally-reared fish (Maynard et al. 1996b). When these techniques are incorporated into production releases, they should also translate into increased smolt-to-adult survival. Conservation and supplementation programs can use NATURES-reared salmonids to rebuild stocks currently listed as endangered and threatened into healthy self-sustaining runs more rapidly than traditional programs. Traditional production programs can also use high-survival NATURES-reared fish to reduce their impact on wild populations, while still meeting their adult mitigation goals.
- Research Organization:
- United States. National Oceanic and Atmospheric Administration.
- Sponsoring Organization:
- United States. Bonneville Power Administration.
- DOE Contract Number:
- 00000548
- OSTI ID:
- 815122
- Report Number(s):
- DOE/BP-00000548-1; TRN: US200318%%399
- Resource Relation:
- Other Information: PBD: 25 Feb 2003; Related Information: "prepared by Desmond J. Maynard, ... [et al.]."
- Country of Publication:
- United States
- Language:
- English
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