Diet of post‐smolt and one‐sea‐winter Atlantic salmon in the Bothnian Sea, Northern Baltic

Salminen, Matti; Erkamo, Esa; Salmi, Juhani

doi:10.1111/j.1095-8649.2001.tb00496.x

Cited by 46 publications

(57 citation statements)

References 18 publications

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“…In contrast, grey seals prefer larger herring (Lundstro¨m et al 2010) grey seal predation on age-6 herring may reflect this preference for larger-sized herring (Lundstro¨m et al 2010). Although herring is a key prey for other migratory predatory fishes, e.g., constituting over 70% of the diet for post-smolt salmon (Salminen et al 2001), impact of these predators on herring population dynamics is probably minor due to highly seasonal spatial overlap and their relatively small population sizes (ICES 2010c).…”

Section: Discussionmentioning

confidence: 99%

Interacting trophic forcing and the population dynamics of herring

Lindegren

Östman

Gårdmark

2011

Ecology

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Abstract. Small pelagic fish occupy a central position in marine ecosystems worldwide, largely by determining the energy transfer from lower trophic levels to predators at the top of the food web, including humans. Population dynamics of small pelagic fish may therefore be regulated neither strictly bottom-up nor top-down, but rather through multiple external and internal drivers. While in many studies single drivers have been identified, potential synergies of multiple factors, as well as their relative importance in regulating population dynamics of small pelagic fish, is a largely unresolved issue. Using a statistical, age-structured modeling approach, we demonstrate the relative importance and influence of bottom-up (e.g., climate, zooplankton availability) and top-down (i.e., fishing and predation) factors on the population dynamics of Bothnian Sea herring (Clupea harengus) throughout its life cycle. Our results indicate significant bottom-up effects of zooplankton and interspecific competition from sprat (Sprattus sprattus), particularly on younger age classes of herring. Although top-down forcing through fishing and predation by grey seals (Halichoerus grypus) and Atlantic cod (Gadus morhua) also was evident, these factors were less important than resource availability and interspecific competition. Understanding key ecological processes and interactions is fundamental to ecosystem-based management practices necessary to promote sustainable exploitation of small pelagic fish.

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Section: Discussionmentioning

confidence: 99%

Interacting trophic forcing and the population dynamics of herring

Lindegren

Östman

Gårdmark

2011

Ecology

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“…As these factors are likely to be interdependent, they should be combined in one study to get a proper picture of Nile perch foraging. Such knowledge is important as, for instance, ontogenetic niche shifts may affect the dynamics of predator populations (Olson, 1996;Van Densen et al, 1996;Ludsin & DeVries, 1997;Salminen et al, 2001;Post, 2003). The present study aims to establish the feeding habits of juvenile Nile perch with a size range of 1-30 cm total length (TL) during a 1 year period along a trajectory in the Mwanza Gulf, from the very shallow inner parts to the deep entrance of the gulf.…”

Section: Introductionmentioning

confidence: 98%

Spatial and seasonal patterns in the feeding habits of juvenile Lates niloticus (L.), in the Mwanza Gulf of Lake Victoria

Katunzi

Densen²,

Wanink

et al. 2006

Hydrobiologia

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Flexibility in the feeding habits of juvenile Nile perch (1-30 cm total length) was studied from September 1988 to September 1989 at four sites (depth range: 1-25 m) in the Mwanza Gulf of Lake Victoria. During this period haplochromine cichlids were virtually absent in the area. We looked at the combined effects of predator size, season and habitat. Stomach content analysis showed that with increase in size, the diet of Nile perch shifted from zooplankton and midge larvae, to macro-invertebrates (shrimps and dragonfly nymphs) and fish. At a size of 3-4 cm Nile perch shifted from size-selective predation on the largest cyclopoids to predation on the largest, less abundant, calanoids. Zooplanktivory ended at a size of ca. 5 cm. Although an ontogenetic shift in the diet of juvenile Nile perch was obvious at all sampling stations, the contribution of prey types appeared to be habitat related. With increasing water depth the frequency of occurrence in the diet of most prey types decreased, but that of shrimps increased. At the entrance of the gulf (20-25 m deep) shrimps were the main food source throughout the year. Halfway the gulf (12-16 m), Nile perch showed seasonality in their feeding behaviour. Shrimps were taken there especially during the rainy season (January to May) when their densities at this station were high, whereas cannibalism prevailed during the rest of the year. In an environment with Nile perch and dagaa as alternative prey, shrimps were taken almost exclusively. They could be regarded as a key prey for Nile perch between 5 and 30 cm.

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“…1). Accordingly, the proportions of sprat and herring vary in the salmon diet [19][20][21], since salmon apparently prey on the most available species of an appropriate size. The BPr is the main spawning ground of sprat [22,23].…”

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confidence: 99%

“…Sprat do not reproduce in the BS due to the low salinity [23]. Following the explosive growth of the Baltic sprat stock in the early 1990s, some sprat have annually dispersed to the BS from more southern parts of the Baltic Sea [19,20], but the proportion of sprat in the salmon prey biomass in the BS has remained <5−10% [17]. In the GoF, sprat might have been more abundant than herring from the years of strong sprat recruitment onwards, although herring was previously the dominant prey species of salmon in the area [26,27].…”

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Fatty acid composition of sprat (Sprattus sprattus) and herring (Clupea harengus) in the Baltic Sea as potential prey for salmon (Salmo salar)

et al. 2017

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Sprat (Sprattus sprattus) and small herring (Clupea harengus) are the dominant prey fish of Atlantic salmon (Salmo salar) in the Baltic Sea. If the fatty acid (FA) proportions of sprat and herring differ, the dietary history of ascending salmon could be determined from their FA profiles. Therefore, we investigated the FA composition of several age groups of whole sprat and small herring, caught from the three main feeding areas of salmon in autumn and spring. Oleic acid (18:1n-9) was the most prevalent FA in sprat and characteristic of this species. In herring, palmitic acid (16:0) was the most common FA, but herring lipid was characterized by n-6 polyunsaturated FAs, and moreover, by palmitoleic acid (16:1n-7) and vaccenic acid (18:1n-7). Due to the higher lipid content of sprat, the concentrations of all other FAs, excluding these, were higher in sprat than in herring. The concentration of docosahexaenoic acid (DHA, 22:6n-3) increased with an increase in the lipid content and was consequently highest in the youngest specimens, being in young sprat almost double that of young herring, and 2.6 times higher in the sprat biomass than in that of herring. As a result of a decrease in the DHA concentration with age, the ratio thiamine/DHA increased with respect to age in both species, and was lower in sprat than in herring. It is concluded that an abundance of DHA in the diet of salmon most likely increases oxidative stress because of the susceptibility of DHA to peroxidation, and thus decreases thiamine resources of fasting, prespawning salmon. Because the FA composition of sprat and herring differs, and the relative abundancies of prey fish differ between the feeding areas of salmon, the feeding area of ascending salmon can most probably be derived by comparing their FA profiles.

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Diet of post‐smolt and one‐sea‐winter Atlantic salmon in the Bothnian Sea, Northern Baltic

Cited by 46 publications

References 18 publications

Interacting trophic forcing and the population dynamics of herring

Interacting trophic forcing and the population dynamics of herring

Spatial and seasonal patterns in the feeding habits of juvenile Lates niloticus (L.), in the Mwanza Gulf of Lake Victoria

Fatty acid composition of sprat (Sprattus sprattus) and herring (Clupea harengus) in the Baltic Sea as potential prey for salmon (Salmo salar)

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