Stocking experiments with 0 + and 1 + trout parr, <i>Salmo trutta</i> L., of wild and hatchery origin: 1. Post‐stocking mortality and smolt yield

Berg, Søren; Jorgensen, Jeffrey C.

doi:10.1111/j.1095-8649.1991.tb04353.x

Cited by 49 publications

(36 citation statements)

References 36 publications

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“…In addition, to avoid the negative effects of density-dependent growth, scatter stocking is preferable to point stocking. As noted by Berg & Jørgensen (1991) stocking fish at higher densities than the carrying capacity of the stream could be more harmful than beneficial, as the consequent overall reduced growth rate may result in a collapse of the trout population in the stream.…”

Section: Discussionmentioning

confidence: 95%

Density-dependent individual growth of marble trout (Salmo marmoratus) in the Soca and Idrijca river basins, Slovenia

Vincenzi

Crivellì

Jeseňsek³

et al. 2007

Hydrobiologia

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Although the main features of salmonid life cycles are currently well known, marble trout (Salmo marmoratus) populations have been scarcely studied due to the present limited geographical distribution of the species. In this work we tested the hypothesis of density-dependent individual growth of marble trout with data gathered from multi-year on-going monitoring started in 1996 in three streams (Zakojska, Gorska and Gatsnik) in the Soca and Idrijca river basins (Slovenia). As observed for other salmonid species, marble trout exhibits high plasticity in body size and growth in response to environmental conditions. Age-specific mean lengths are significantly different among the three streams. Despite this variability, the statistical analyses outlined some clear patterns. Mean lengths of marble trout cohorts aged ‡1+ are correlated with total population density in the first year of life of the cohorts; the age-specific relationship between mean length and total density is well explained by negative power curves. Length of marble trout at age 1+ is significantly correlated with length at subsequent years up to age 4+. ANCOVAs performed on the stream-specific datasets showed a significant effect of total density of marble trout on annual age-specific individual growth rates. Von Bertalanffy's body growth models were calibrated on length-age data of Zakojska and Gorska marble trout. Our analysis shows the existence of density-dependent effects on growth of marble trout that might be crucial in regulating population dynamics.

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Section: Discussionmentioning

confidence: 95%

Density-dependent individual growth of marble trout (Salmo marmoratus) in the Soca and Idrijca river basins, Slovenia

Vincenzi

Crivellì

Jeseňsek³

et al. 2007

Hydrobiologia

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“…These stockings have been carried out systematically, based on an assessment of the carrying capacity of the streams (Geertz- Hansen and Jørgensen, 1996). There has been an increasing concern about the side effects on wild fish of fish stocking, such as increased competition, genetic dilution and increased fishing mortality (Berg and Jørgensen, 1991;Hansen et al, 1995;Johnsson et al, 1999;Petersson and Järvi, 2006). Consequently, an increasing focus has been placed on developing alternative long-lasting rehabilitation methods to efficiently improve the living conditions for salmonids (Cowx, 1994).…”

Section: Introductionmentioning

confidence: 99%

Ecological effects of re‐introduction of salmonid spawning gravel in lowland Danish streams

Pedersen

Kristensen

Kronvang

et al. 2009

River Research & Apps

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During the past centuries natural spawning gravel was removed during the regulation of many streams in the Northern Hemisphere and wild fish stocks subsequently suffered due to this severe habitat degradation. To improve spawning conditions, projects involving reintroduction of spawning gravel have recently been conducted in many streams and rivers. However, systematic monitoring of these spawning gravel restoration projects is limited.The overall aim of this paper was to evaluate gravel reintroduction as a long-term salmonid rehabilitation method in 32 lowland streams. Displacement of gravel and abundance of original gravel was assessed on each site along with spawning activity and density of fry. In three streams, Gels Å , Stensbaek and Ryds Å , intensive studies of spawning activity, nursery habitat development and densities of trout fry and young-of-the-year (YOY), were performed the following year, including both restored reaches and upstream control reaches.Downstream displacement of gravel was most common at sites where gravel was reintroduced without further improvement, although these sites exhibited the highest density of YOY brown trout (Salmo trutta), evidencing that the remaining gravel is still functional. The intensive study of three streams showed that spawning was enhanced by the introduction of spawning gravel at the restored sites compared to control sites and that habitat quality generally were improved. Our results also suggest complex interactions exist between spawning activity, migrating trout and the emergence and survival of fry and YOY trout and the habitat conditions provided in regulated lowland Danish streams.Our results clearly indicate that reintroduction of spawning gravel to restore fish populations in river systems warrants consideration of the differences in habitat quality that may occur among the reaches within a river system. Furthermore, spawning and nursery habitats should be present in all reaches to enhance survival of trout on re-instated gravel. To increase our knowledge of spawning gravel restoration systematic monitoring and assessment out of projects are required following project implementation.

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“…The addition of uS in this model represents the competitive impact of stocked hatchery YOY fish (S) that immediately survive following stocking, given a stocking survival rate u. Initial stocking mortality (represented by u) is characteristic of most stocking events and is often attributed to, for example, poor foraging efficiency, underdeveloped predator avoidance behavior, or transportation-induced poststocking mortality (49). The use of a Beverton-Holt type survival in Eq.…”

Section: Methodsmentioning

confidence: 99%

Social-ecological interactions, management panaceas, and the future of wild fish populations

Poorten

Arlinghaus

Daedlow

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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We explored the social and ecological outcomes associated with emergence of a management panacea designed to govern a stochastic renewable natural resource. To that end, we constructed a model of a coupled social-ecological system of recreational fisheries in which a manager supports naturally fluctuating stocks by stocking fish in response to harvest-driven satisfaction of resource users. The realistic assumption of users remembering past harvest experiences when exploiting a stochastically fluctuating fish population facilitates the emergence of a stocking-based management panacea over time. The social benefits of panacea formation involve dampening natural population fluctuations and generating stability of user satisfaction. It also maintains the resource but promotes the eventual replacement of wild fish by hatchery-descended fish. Our analyses show this outcome is particularly likely when hatcherydescended fish are reasonably fit (e.g., characterized by similar survival relative to wild fish) and/or when natural recruitment of the wild population is low (e.g., attributable to habitat deterioration), which leaves the wild population with little buffer against competition by stocked fish. The potential for release-based panacea formation is particularly likely under user-based management regimes and should be common in a range of social-ecological systems (e.g., fisheries, forestry), whenever user groups are entitled to engage in release or replanting strategies. The net result will be the preservation of a renewable resource through user-based incentives, but the once natural populations are likely to be altered and to host nonnative genotypes. This risks other ecosystem services and the future of wild populations.stocking panacea | wild population collapse | angler satisfaction | social-ecological model | cultural ecosystem service

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Stocking experiments with 0 + and 1 + trout parr, Salmo trutta L., of wild and hatchery origin: 1. Post‐stocking mortality and smolt yield

Cited by 49 publications

References 36 publications

Density-dependent individual growth of marble trout (Salmo marmoratus) in the Soca and Idrijca river basins, Slovenia

Density-dependent individual growth of marble trout (Salmo marmoratus) in the Soca and Idrijca river basins, Slovenia

Ecological effects of re‐introduction of salmonid spawning gravel in lowland Danish streams

Social-ecological interactions, management panaceas, and the future of wild fish populations

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