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Jérôme Spitz, Emeline Mourocq, Valérie Schoen, Vincent Ridoux, Proximate composition and energy content of forage species from the Bay of Biscay: high- or low-quality food?, ICES Journal of Marine Science, Volume 67, Issue 5, July 2010, Pages 909–915, https://doi.org/10.1093/icesjms/fsq008
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Abstract
Collapses of high-energy dense concentrations of prey species induce negative effects on populations of top predators. Knowledge of prey quality appears to be crucial in ecosystem modelling and management. The aim here was to provide baseline data of forage species quality in the Bay of Biscay. Proximate composition (water, ash, protein, and lipid) and energy content have been determined to assess the quality of 78 species, including jellyfish, crustaceans, cephalopods, cartilaginous fish, and bony fish. Results show broad variations between species, with energy densities ranging from 2 to 10 kJ g−1. Lipids are the most structuring component and largely determined prey quality, and prey species are not necessarily interchangeable for the fulfilment of a predator's energy and food requirements. In ecosystem models, therefore, multispecies compartments of forage organisms would ideally be constituted using prey species of equivalent quality and hence of equivalent benefit to top predators.Spitz, J., Mourocq, E., Schoen, V., and Ridoux, V. 2010. Proximate composition and energy content of forage species from the Bay of Biscay: high- or low-quality food? – ICES Journal of Marine Science, 67: 909–915.
Introduction
In oceans subjected to climatic pressures and human impacts such as global warming or overfishing, the distribution and abundance of some marine resources have been and will be increasingly modified (Dulvy et al., 2008; Cheung et al., 2009). Subsequent shifts in prey availability could affect the fitness of predator species. Indeed, even if the overall biomass and biodiversity remain unchanged, predator fulfilments of nutritional and energy requirements could be jeopardized by a decrease in prey quality. Collapses of fat and high-energy dense concentrations of prey species coupled with an increase in lower-quality prey availability induce negative effects on top predator populations around the world (Österblom et al., 2008). For example, the decline in Steller sea lions (Eumetopias jubatus) in Alaska was tentatively linked to a shift from high-energy density prey to low-fat fish such as walleye pollock (Theragra chalcogramma; Trites and Donnelly, 2003). Therefore, in addition to prey abundance, the knowledge of prey quality appears to be crucial in ecosystem modelling and management.
Ecosystems in the Bay of Biscay and adjacent northeast Atlantic Ocean are exploited by numerous fisheries and support a large diversity of top predators. The importance of fat fish for some cetaceans in this area was recently suggested by the description of their diet (Spitz et al., 2006; Pusineri et al., 2007). The most striking case was that of the common dolphin (Delphinus delphis), which maintains a large proportion of fat fish in its diet despite extensive variations in the main prey species across seasons (Meynier et al., 2008). Some of these prey species, such as anchovy or herring, are commercially important and show very low levels of spawning-stock biomass (ICES, 2009a, b). At the same time, an increase in potentially low-quality prey such as snake pipefish (Entelurus aequoreus) was observed (Harris et al., 2007). If these changes in the availability of forage species induce a reduction in food quality, i.e. a reduction in the number of calories per unit of prey biomass, the population dynamics of top predators could be affected dramatically.
Quality of food should therefore be considered in ecosystem modelling, rather than biomass alone. Indeed, considering variability in prey quality, one unit biomass of a given species is not necessarily equivalent to one unit biomass of another species sharing a similar trophic level but with a distinct body composition. As the output of such modelling strongly depends on the accuracy of foodweb structure taken into account by the model (Christensen and Walters, 2004), variation in prey quality should be examined within each box of the ecosystem.
The aim of the present study was to provide, at a large taxonomic scale, baseline data of lipid, protein, water, ash, and energy contents of forage species in the Bay of Biscay and adjacent northeast Atlantic Ocean to suggest functional groups based on prey quality for further use in ecosystem modelling.
Material and methods
Almost all forage species were collected from 2002 to 2008 in the Bay of Biscay during EVHOE (EValuation des ressources Halieutiques de l'Ouest Européen) research cruises carried out from Ifremer's RV “Thalassa” in autumn each year. Some additional materials, especially for coastal or rocky species, were specifically sampled during the same period. Species were identified following published guides (e.g. Whitehead et al., 1986; Quéro et al., 2003). Totals of 5472 specimens from 78 different species (1 jellyfish, 7 crustaceans, 8 cephalopods, 3 cartilaginous fish, and 59 bony fish) were sampled. As far as possible, the size range was selected to match published prey sizes for top predators in the Bay of Biscay (Spitz et al., 2006; Pusineri et al., 2007; Meynier et al., 2008). All material was stored frozen at −20°C until further analysis.
Proximate composition (water, ash, protein, and lipid) and calorific content were determined to evaluate the quality of forage species. To reduce inter-individual variability, multiple individual samples were pooled for each species. Pools of whole specimens were freeze-dried and reduced to powder.
Following the Association of Official Analytical Chemists (AOAC, 1990), total water content was determined by weighing the samples on an electronic balance before and after freeze-drying and again after final drying in an oven at 105°C. Ash was determined by heating the sample in a furnace for ∼12 h at 550°C (AOAC, 1990). Total protein was determined by the measurement of total nitrogen concentrations following the Kjeldahl method (AOAC, 1990). To convert total nitrogen to total protein, a conversion factor of 6.25 was applied for all forage species (Chen et al., 1988). Total lipid content was determined using Soxhlet equipment with an ether-ethyl solvent (Radin, 1981). Carbohydrate content was not measured because that component is generally low in marine forage species and its contribution to total energy content is close to zero (Anthony et al., 2000; Eder and Lewis, 2005). Energy contents were estimated using adiabatic bomb-calorimetry in which gross energy was determined by measuring heat of combustion.
Ash, lipid, protein, and energy contents were originally measured on dry samples. They were converted to wet mass by taking water content into account. Therefore, ash, lipid and protein contents are expressed in percentage wet total body mass and energy content in kJ g−1 wet total body mass. All values provided are means of duplicate determination (deviation between two assays was <2%). Several species were analysed in different years (n > 1 in Table 1).
Group . | Order . | Family . | Species . | N . | n . | Length . | Water . | Proteins . | Lipids . | Ash . | Energy . |
---|---|---|---|---|---|---|---|---|---|---|---|
Jellyfish | Semaeostomeae | Ulmaridae | Aurelia aurita | 30 | 1 | [8–12] | 92.1 | 2.1 | 0.3 | 4.2 | 0.7 |
Crustaceans 4.8 [3.4–6.9]* | Eucaria | Euphausiidae | Meganyctiphanes norvegica | 704 | 1 | [2–3] | 77.8 | 15.8 | 1.2 | 3.8 | 3.9 |
Decapoda (macrurans) 4.3 [3.4–5.3] | Oplophoridae | Acanthephyra purpurea | 480 | 1 | [3–6] | 88.4 | 16 | 4.3 | 4.5 | 5.3 | |
Palaemonidae | Palaemon longirostris | 612 | 1 | [1–2] | 82.4 | 11.5 | 1.5 | 2.9 | 3.4 | ||
Pasiphaeidae | Pasiphaea sivado | 342 | 1 | [4–9] | 78.1 | 17.6 | 0.5 | 3.4 | 4.1 | ||
Decapoda (brachyurans) 5.6 [4.2–6.9] | Grapsidae | Pachygrapsus marmoratus | 25 | 1 | [23–40] | 60.1 | 19.9 | 1 | 14.4 | 5.8 | |
Portunidae 5.5 [4.2–6.9] | Polybius henslowii | 37 | 1 | [4–5] | 72.4 | 14.1 | 1.4 | 8.8 | 4.2 | ||
Necora puber | 8 | 1 | [4–7] | 62.8 | 22.8 | 2 | 7.7 | 6.9 | |||
Cephalopods 4.4 [3.8–4.8] | Teuthoidea 4.4 [3.9–4.8] | Loliginidae 4.4 [3.9–4.8] | Allotheutis spp. | 221 | 4 | [3–8] | 78.9 [78.1–80.8] | 16.4 [14.5–16.7] | 1.3 [0.8–1.8] | 1.7 [1.6–2.0] | 3.9 [3.6–4.2] |
Loligo forbesi | 4 | 1 | [10–21] | 76.5 | 17.9 | 2.2 | 2 | 4.6 | |||
Loligo vulgaris | 15 | 5 | [12–25] | 76.2 [75.4–77.0] | 18.9 [18.1–19.6] | 1.5 [0.7–2.2] | 1.7 [1.6–1.9] | 4.8 [4.4–5.3] | |||
Ommastrephidae 4.4 [4.3–4.4] | Illex coindeti | 9 | 3 | [14–17] | 77.8 [77.0–79.2] | 17.3 [15.2–18.7] | 1.9 [1.5–2.2] | 1.6 [1.5–1.8] | 4.3 [4.1–4.4] | ||
Todaropsis eblanae | 9 | 3 | [12–15] | 77.8 [77.7–78.0] | 18 [16.0–19.4] | 2.4 [2.3–2.6] | 1.8 [1.7–1.9] | 4.4 [4.3–4.5] | |||
Sepiolida | Sepiolidae | Sepiola spp. | 77 | 1 | [1–2] | 77.4 | 16 | 2 | 2.6 | 4.8 | |
Sepioidea | Sepiidae | Sepia officinalis | 10 | 2 | [6–10] | 75.8 [75.7–75.9] | 15.8 [15.3–16.4] | 1.2 [1.0–1.4] | 5.5 [5.2–5.8] | 3.8 [3.6–3.9] | |
Octopoda | Octopodidae | Eledone cirrhosa | 3 | 1 | [10–11] | 76 | 16.2 | 2.8 | 2.2 | 4.7 | |
Cartilaginous fish 5.3 [3.9–6.4] | Carcharhiniformes | Scyliorhinidae | Scyliorhinus canicula | 3 | 1 | [48–51] | 72.1 | 22.6 | 5.1 | 2.3 | 6.4 |
Rajiformes | Rajidae | Leucoraja naevus | 3 | 1 | [40–51] | 75.5 | 20.7 | 4.1 | 1.6 | 5.7 | |
Chimaeriformes | Chimaeridae | Chimaera monstrosa | 6 | 1 | [9–10] | 81.3 | 16.4 | 2.2 | 2 | 3.9 | |
Bony fish 5.7 [2.1–10.2] | Anguilliformes 4.5 [2.1–6.9] | Congridae | Conger conger | 3 | 1 | [53–60] | 72.8 | 18.8 | 5.2 | 1.7 | 6.9 |
Serrivomeridae | Serrivomer beanii | 26 | 1 | [21–65] | 78.1 | 8.4 | 1.1 | 2.3 | 2.1 | ||
Clupeiformes 7.8 [5.8–10.1] | Clupeidae 8.5 [6.5–10.1] | Sprattus sprattus | 246 | 4 | [7–13] | 70.9 [69.1–75.4] | 17.2 [16.4–18.2] | 8.2 [3.4–11.2] | 2.5 [2.3–2.7] | 6.5 [4.8–7.3] | |
Sardina pilchardus | 15 | 3 | [14–22] | 65.3 [63.2–67.4] | 17.8 [16.7–19.1] | 11.7 [8.4–17.1] | 2.4 [1.8–3.3] | 8.7 [7.5–10.1] | |||
Clupea harengus | 3 | 1 | [20–20] | 62.8 | 18.6 | 10.7 | 3.6 | 10.2 | |||
Engraulidae | Engraulis encrasicolus | 208 | 4 | [9–13] | 72.0 [69.0–76.0] | 19.6 [18.2–20.3] | 3.4 [1.7–5.2] | 2.8 [1.9–3.2] | 5.8 [4.9–6.7] | ||
Osmeriformes 3.6 [2.6–6.1] | Alepocephalidae | Xenodermichtys copei | 173 | 1 | [4–12] | 87.5 | 9.6 | 0.4 | 2.4 | 2.2 | |
Argentinidae | Argentina sphyraena | 22 | 2 | [11–16] | 72.2 [71.5–72.2] | 17.8 [16.5–19.0] | 5.7 [5.2–6.1] | 2.5 [2.5–2.5] | 6.1 [6.0–6.2] | ||
Platytroctidae | Normichthys operosa | 53 | 1 | [7–16] | 77.2 | 11 | 0.8 | 2.5 | 2.6 | ||
Stomiiformes 3.5 [2.8–4.2] | Sternoptychidae 3.9 [3.5–4.2] | Argyropelecus olfersii | 138 | 1 | [1–10] | 69.2 | 14.8 | 1.3 | 5.3 | 3.5 | |
Maurolicus muelleri | 201 | 1 | [3–5] | 76.3 | 13.5 | 5.2 | 3.7 | 4.2 | |||
Stomiidae | Stomias boa ferox | 28 | 1 | [8–31] | 88.4 | 11.5 | 1.2 | 3.1 | 2.8 | ||
Aulopiformes | Paralepididae | Arctozenus risso | 124 | 1 | [9–20] | 88.4 | 15.8 | 2.5 | 3.4 | 4.3 | |
Myctophiformes 6.6 [4.1–8.6] | Myctophidae 6.6 [4.1–8.6] | Lampanyctus crocodilus | 63 | 1 | [7–15] | 74.7 | 16.1 | 1.6 | 2.9 | 4.1 | |
Benthosema glaciale | 697 | 1 | [2–6] | 85.5 | 13.9 | 7.5 | 3.4 | 5.9 | |||
Notoscopelus kroyeri | 60 | 1 | [3–13] | 87.5 | 16.6 | 11.9 | 2.3 | 7.9 | |||
Lobianchia gemellari | 30 | 1 | [7–9] | 67.1 | 18.8 | 8.6 | 2.1 | 8.6 | |||
Gadiformes 4.7 [3.7–5.5] | Macrouridae | Coelorinchus coelorinchus | 5 | 1 | [8–10] | 77.6 | 16.2 | 2.6 | 3 | 5.1 | |
Gadidae 4.5 [3.9–5.5] | Merlangius merlangus | 24 | 4 | [17–22] | 79.5 [79.3–79.7] | 16.7 [16.6–16.9] | 0.7 [0.3–1.0] | 2.9 [2.3–3.5] | 3.9 [3.8–3.9] | ||
Pollachius pollachius | 2 | 1 | [29–30] | 79 | 17.2 | 0.7 | 2.8 | 4.2 | |||
Micromesistius poutassou | 40 | 4 | [14–20] | 77.9 [77.0–78.3] | 17.4 [16.1–18.1] | 1.5 [1.1–1.7] | 3.1 [2.2–4.0] | 4.4 [4.0–4.7] | |||
Trisopterus luscus | 9 | 3 | [22–26] | 77.3 [76.9–78.2] | 17.7 [16.8–19.2] | 1.8 [1.2–2.3] | 2.9 [1.7–4.2] | 4.7 [4.6–5.0] | |||
Gadiculus argenteus | 23 | 1 | [8–11] | 75.5 | 16.2 | 3.7 | 3.4 | 5 | |||
Trisopterus minutus | 21 | 3 | [14–18] | 73.8 [71.5–75.3] | 18.8 [17.9–20.3] | 2.8 [2.4–3.3] | 3.5 [2.3–4.7] | 5.1 [5.0–5.2] | |||
Gaidropsarus spp. | 5 | 1 | [14–23] | 76.8 | 17.2 | 2.6 | 1.9 | 5.5 | |||
Phycidae | Phycis blennoides | 3 | 1 | [26–28] | 77.5 | 17.4 | 2.5 | 2.7 | 5 | ||
Merlucciidae | Merluccius merluccius | 9 | 3 | [22–29] | 80.4 [79.5–81.2] | 16 [15.1–16.9] | 0.7 [0.3–1.1] | 2.7 [2.2–3.2] | 3.7 [3.4–3.9] | ||
Atheriniformes | Atherinidae | Atherina presbyter | 129 | 3 | [5–12] | 67.8 [65.9–68.8] | 19.8 [18.9–21.2] | 7.3 [6.6–8.1] | 3 [2.1–3.7] | 7.3 [7.1–7.5] | |
Beloniformes 6.0 [5.8–6.2] | Belonidae | Belone belone | 3 | 1 | [55–59] | 74 | 20.1 | 2.9 | 2.7 | 6.2 | |
Scomberesocidae | Scomberesox saurus | 5 | 1 | [25–30] | 71.6 | 22.9 | 2.1 | 2.4 | 5.8 | ||
Beryciformes | Trachichthyidae | Hoplostethus mediterraneus | 17 | 1 | [4–7] | 75.9 | 15.9 | 2.3 | 4.9 | 4.7 | |
Zeiformes | Caproidae | Capros aper | 36 | 1 | [6–7] | 71.3 | 17.2 | 4.8 | 4.6 | 6.2 | |
Syngnathiformes | Syngnathinae | Entelurus aequoreus | 128 | 1 | [25–34] | 73.5 | 14.7 | 1.9 | 6.8 | 4.7 | |
Scorpaeniformes 7.5 [5.1–9.2] | Sebastinae | Helicolenus dactylopterus | 3 | 1 | [15–17] | 65.7 | 18.2 | 12.2 | 2.6 | 9.2 | |
Scorpaenidae | Scorpaena loppei | 3 | 1 | [91–98] | 73.2 | 20.2 | 1.4 | 4.1 | 5.1 | ||
Triglidae | Chelidonichthys cuculus | 7 | 2 | [17–20] | 69.0 [66.9–71.1] | 19.8 [18.9–20.6] | 6.9 [5.5–8.2] | 2.9 [2.3–3.5] | 8.2 [7.8–8.5] | ||
Perciformes 6.2 [4.8–9.4] | Moronidae | Dicentrarchus labrax | 3 | 1 | [44–48] | 84.1 | 20.2 | 4.5 | 2 | 6 | |
Carangidae | Trachurus trachurus | 30 | 5 | [14–30] | 72.4 [71.1–74.0] | 18.2 [17.3–19.0] | 5 [3.6–6.2] | 3.1 [2.4–4.5] | 6 [5.6–6.5] | ||
Sparidae 8.1 [6.9–9.4] | Spondyliosoma cantharus | 6 | 2 | [17–23] | 69.9 [68.5–71.3] | 18.3 [18.0–18.6] | 6.8 [5.0–8.7] | 2.5 [2.2–2.8] | 6.9 [6.4–7.4] | ||
Boops boops | 9 | 1 | [14–25] | 67 | 19.8 | 5.8 | 2.3 | 8 | |||
Pagellus acarne | 4 | 1 | [15–17] | 65.1 | 19.7 | 10.9 | 2.4 | 9.4 | |||
Mullidae | Mullus surmuletus | 15 | 2 | [11–14] | 71.7 [71.4–71.9] | 18.7 [18.2–19.1] | 4.5 [4.1–4.9] | 2.7 [2.5–2.9] | 6.4 [6.3–6.4] | ||
Cepolidae | Cepola macrophthalma | 6 | 1 | [38–53] | 80.2 | 14.2 | 1.1 | 4.1 | 3.9 | ||
Mugilidae | Liza ramada | 3 | 1 | [33–42] | 67.6 | 23.7 | 3.4 | 3.6 | 6.5 | ||
Labridae | Labrus bergylta | 2 | 1 | [28–32] | 75.8 | 20 | 1.6 | 1.9 | 5.4 | ||
Ammodytidae 5.3 [4.8–5.8] | Hyperoplus lanceolatus | 6 | 1 | [30–37] | 75.1 | 18.1 | 0.9 | 3.2 | 4.8 | ||
Ammodytes tobianus | 9 | 2 | [27–31] | 73.5 [73.5–73.6] | 18.9 [18.9–18.9] | 4.1 [3.8–4.4] | 2 [1.9–2.1] | 5.8 [5.7–5.8] | |||
Trachinidae | Trachinus draco | 5 | 1 | [18–23] | 74.6 | 18.2 | 1.4 | 3.9 | 5.3 | ||
Blenniidae | Paralipophrys trigloides | 16 | 1 | [7–12] | 73.1 | 19.1 | 2 | 3.5 | 5.5 | ||
Callionymidae | Callionymus lyra | 5 | 1 | [15–19] | 75.4 | 17.1 | 2 | 3.6 | 5.2 | ||
Gobiidae | Lesueurigobius friesii | 143 | 1 | [4–6] | 72.4 | 16.5 | 4.1 | 4.8 | 5.6 | ||
Scombridae | Scomber scombrus | 12 | 4 | [25–29] | 67.3 [66.4–69.9] | 17.5 [17.3–17.8] | 10.5 [7.9–13.6] | 2.1 [1.8–2.4] | 7.9 [7.1–8.5] | ||
Pleuronectiformes 5.7 [5.0–6.5] | Scophthalmidae | Lepidorhombus whiffiagonis | 3 | 1 | [21–26] | 73.9 | 18.1 | 3.1 | 2.3 | 6.1 | |
Bothidae | Arnoglossus imperialis | 19 | 1 | [8–14] | 74 | 18.8 | 1.8 | 3.6 | 5.4 | ||
Pleuronectidae 5.7 [5.6–5.8] | Glyptocephalus cynoglossus | 2 | 1 | [29–34] | 76.6 | 17.4 | 3.4 | 2.1 | 5.6 | ||
Microstomus kitt | 2 | 1 | [28–29] | 73.9 | 19.8 | 2.8 | 2.2 | 5.8 | |||
Pleuronectes platessa | 2 | 1 | [27–34] | 74.3 | 17.9 | 3.1 | 3 | 5.8 | |||
Soleidae 5,8 [5–6.5] | Solea solea | 3 | 1 | [28–31] | 77.0 | 18.9 | 1.5 | 2.1 | 5 | ||
Dicologlossa cuneata | 7 | 1 | [12–20] | 69.2 | 21.9 | 3.7 | 3 | 6.5 |
Group . | Order . | Family . | Species . | N . | n . | Length . | Water . | Proteins . | Lipids . | Ash . | Energy . |
---|---|---|---|---|---|---|---|---|---|---|---|
Jellyfish | Semaeostomeae | Ulmaridae | Aurelia aurita | 30 | 1 | [8–12] | 92.1 | 2.1 | 0.3 | 4.2 | 0.7 |
Crustaceans 4.8 [3.4–6.9]* | Eucaria | Euphausiidae | Meganyctiphanes norvegica | 704 | 1 | [2–3] | 77.8 | 15.8 | 1.2 | 3.8 | 3.9 |
Decapoda (macrurans) 4.3 [3.4–5.3] | Oplophoridae | Acanthephyra purpurea | 480 | 1 | [3–6] | 88.4 | 16 | 4.3 | 4.5 | 5.3 | |
Palaemonidae | Palaemon longirostris | 612 | 1 | [1–2] | 82.4 | 11.5 | 1.5 | 2.9 | 3.4 | ||
Pasiphaeidae | Pasiphaea sivado | 342 | 1 | [4–9] | 78.1 | 17.6 | 0.5 | 3.4 | 4.1 | ||
Decapoda (brachyurans) 5.6 [4.2–6.9] | Grapsidae | Pachygrapsus marmoratus | 25 | 1 | [23–40] | 60.1 | 19.9 | 1 | 14.4 | 5.8 | |
Portunidae 5.5 [4.2–6.9] | Polybius henslowii | 37 | 1 | [4–5] | 72.4 | 14.1 | 1.4 | 8.8 | 4.2 | ||
Necora puber | 8 | 1 | [4–7] | 62.8 | 22.8 | 2 | 7.7 | 6.9 | |||
Cephalopods 4.4 [3.8–4.8] | Teuthoidea 4.4 [3.9–4.8] | Loliginidae 4.4 [3.9–4.8] | Allotheutis spp. | 221 | 4 | [3–8] | 78.9 [78.1–80.8] | 16.4 [14.5–16.7] | 1.3 [0.8–1.8] | 1.7 [1.6–2.0] | 3.9 [3.6–4.2] |
Loligo forbesi | 4 | 1 | [10–21] | 76.5 | 17.9 | 2.2 | 2 | 4.6 | |||
Loligo vulgaris | 15 | 5 | [12–25] | 76.2 [75.4–77.0] | 18.9 [18.1–19.6] | 1.5 [0.7–2.2] | 1.7 [1.6–1.9] | 4.8 [4.4–5.3] | |||
Ommastrephidae 4.4 [4.3–4.4] | Illex coindeti | 9 | 3 | [14–17] | 77.8 [77.0–79.2] | 17.3 [15.2–18.7] | 1.9 [1.5–2.2] | 1.6 [1.5–1.8] | 4.3 [4.1–4.4] | ||
Todaropsis eblanae | 9 | 3 | [12–15] | 77.8 [77.7–78.0] | 18 [16.0–19.4] | 2.4 [2.3–2.6] | 1.8 [1.7–1.9] | 4.4 [4.3–4.5] | |||
Sepiolida | Sepiolidae | Sepiola spp. | 77 | 1 | [1–2] | 77.4 | 16 | 2 | 2.6 | 4.8 | |
Sepioidea | Sepiidae | Sepia officinalis | 10 | 2 | [6–10] | 75.8 [75.7–75.9] | 15.8 [15.3–16.4] | 1.2 [1.0–1.4] | 5.5 [5.2–5.8] | 3.8 [3.6–3.9] | |
Octopoda | Octopodidae | Eledone cirrhosa | 3 | 1 | [10–11] | 76 | 16.2 | 2.8 | 2.2 | 4.7 | |
Cartilaginous fish 5.3 [3.9–6.4] | Carcharhiniformes | Scyliorhinidae | Scyliorhinus canicula | 3 | 1 | [48–51] | 72.1 | 22.6 | 5.1 | 2.3 | 6.4 |
Rajiformes | Rajidae | Leucoraja naevus | 3 | 1 | [40–51] | 75.5 | 20.7 | 4.1 | 1.6 | 5.7 | |
Chimaeriformes | Chimaeridae | Chimaera monstrosa | 6 | 1 | [9–10] | 81.3 | 16.4 | 2.2 | 2 | 3.9 | |
Bony fish 5.7 [2.1–10.2] | Anguilliformes 4.5 [2.1–6.9] | Congridae | Conger conger | 3 | 1 | [53–60] | 72.8 | 18.8 | 5.2 | 1.7 | 6.9 |
Serrivomeridae | Serrivomer beanii | 26 | 1 | [21–65] | 78.1 | 8.4 | 1.1 | 2.3 | 2.1 | ||
Clupeiformes 7.8 [5.8–10.1] | Clupeidae 8.5 [6.5–10.1] | Sprattus sprattus | 246 | 4 | [7–13] | 70.9 [69.1–75.4] | 17.2 [16.4–18.2] | 8.2 [3.4–11.2] | 2.5 [2.3–2.7] | 6.5 [4.8–7.3] | |
Sardina pilchardus | 15 | 3 | [14–22] | 65.3 [63.2–67.4] | 17.8 [16.7–19.1] | 11.7 [8.4–17.1] | 2.4 [1.8–3.3] | 8.7 [7.5–10.1] | |||
Clupea harengus | 3 | 1 | [20–20] | 62.8 | 18.6 | 10.7 | 3.6 | 10.2 | |||
Engraulidae | Engraulis encrasicolus | 208 | 4 | [9–13] | 72.0 [69.0–76.0] | 19.6 [18.2–20.3] | 3.4 [1.7–5.2] | 2.8 [1.9–3.2] | 5.8 [4.9–6.7] | ||
Osmeriformes 3.6 [2.6–6.1] | Alepocephalidae | Xenodermichtys copei | 173 | 1 | [4–12] | 87.5 | 9.6 | 0.4 | 2.4 | 2.2 | |
Argentinidae | Argentina sphyraena | 22 | 2 | [11–16] | 72.2 [71.5–72.2] | 17.8 [16.5–19.0] | 5.7 [5.2–6.1] | 2.5 [2.5–2.5] | 6.1 [6.0–6.2] | ||
Platytroctidae | Normichthys operosa | 53 | 1 | [7–16] | 77.2 | 11 | 0.8 | 2.5 | 2.6 | ||
Stomiiformes 3.5 [2.8–4.2] | Sternoptychidae 3.9 [3.5–4.2] | Argyropelecus olfersii | 138 | 1 | [1–10] | 69.2 | 14.8 | 1.3 | 5.3 | 3.5 | |
Maurolicus muelleri | 201 | 1 | [3–5] | 76.3 | 13.5 | 5.2 | 3.7 | 4.2 | |||
Stomiidae | Stomias boa ferox | 28 | 1 | [8–31] | 88.4 | 11.5 | 1.2 | 3.1 | 2.8 | ||
Aulopiformes | Paralepididae | Arctozenus risso | 124 | 1 | [9–20] | 88.4 | 15.8 | 2.5 | 3.4 | 4.3 | |
Myctophiformes 6.6 [4.1–8.6] | Myctophidae 6.6 [4.1–8.6] | Lampanyctus crocodilus | 63 | 1 | [7–15] | 74.7 | 16.1 | 1.6 | 2.9 | 4.1 | |
Benthosema glaciale | 697 | 1 | [2–6] | 85.5 | 13.9 | 7.5 | 3.4 | 5.9 | |||
Notoscopelus kroyeri | 60 | 1 | [3–13] | 87.5 | 16.6 | 11.9 | 2.3 | 7.9 | |||
Lobianchia gemellari | 30 | 1 | [7–9] | 67.1 | 18.8 | 8.6 | 2.1 | 8.6 | |||
Gadiformes 4.7 [3.7–5.5] | Macrouridae | Coelorinchus coelorinchus | 5 | 1 | [8–10] | 77.6 | 16.2 | 2.6 | 3 | 5.1 | |
Gadidae 4.5 [3.9–5.5] | Merlangius merlangus | 24 | 4 | [17–22] | 79.5 [79.3–79.7] | 16.7 [16.6–16.9] | 0.7 [0.3–1.0] | 2.9 [2.3–3.5] | 3.9 [3.8–3.9] | ||
Pollachius pollachius | 2 | 1 | [29–30] | 79 | 17.2 | 0.7 | 2.8 | 4.2 | |||
Micromesistius poutassou | 40 | 4 | [14–20] | 77.9 [77.0–78.3] | 17.4 [16.1–18.1] | 1.5 [1.1–1.7] | 3.1 [2.2–4.0] | 4.4 [4.0–4.7] | |||
Trisopterus luscus | 9 | 3 | [22–26] | 77.3 [76.9–78.2] | 17.7 [16.8–19.2] | 1.8 [1.2–2.3] | 2.9 [1.7–4.2] | 4.7 [4.6–5.0] | |||
Gadiculus argenteus | 23 | 1 | [8–11] | 75.5 | 16.2 | 3.7 | 3.4 | 5 | |||
Trisopterus minutus | 21 | 3 | [14–18] | 73.8 [71.5–75.3] | 18.8 [17.9–20.3] | 2.8 [2.4–3.3] | 3.5 [2.3–4.7] | 5.1 [5.0–5.2] | |||
Gaidropsarus spp. | 5 | 1 | [14–23] | 76.8 | 17.2 | 2.6 | 1.9 | 5.5 | |||
Phycidae | Phycis blennoides | 3 | 1 | [26–28] | 77.5 | 17.4 | 2.5 | 2.7 | 5 | ||
Merlucciidae | Merluccius merluccius | 9 | 3 | [22–29] | 80.4 [79.5–81.2] | 16 [15.1–16.9] | 0.7 [0.3–1.1] | 2.7 [2.2–3.2] | 3.7 [3.4–3.9] | ||
Atheriniformes | Atherinidae | Atherina presbyter | 129 | 3 | [5–12] | 67.8 [65.9–68.8] | 19.8 [18.9–21.2] | 7.3 [6.6–8.1] | 3 [2.1–3.7] | 7.3 [7.1–7.5] | |
Beloniformes 6.0 [5.8–6.2] | Belonidae | Belone belone | 3 | 1 | [55–59] | 74 | 20.1 | 2.9 | 2.7 | 6.2 | |
Scomberesocidae | Scomberesox saurus | 5 | 1 | [25–30] | 71.6 | 22.9 | 2.1 | 2.4 | 5.8 | ||
Beryciformes | Trachichthyidae | Hoplostethus mediterraneus | 17 | 1 | [4–7] | 75.9 | 15.9 | 2.3 | 4.9 | 4.7 | |
Zeiformes | Caproidae | Capros aper | 36 | 1 | [6–7] | 71.3 | 17.2 | 4.8 | 4.6 | 6.2 | |
Syngnathiformes | Syngnathinae | Entelurus aequoreus | 128 | 1 | [25–34] | 73.5 | 14.7 | 1.9 | 6.8 | 4.7 | |
Scorpaeniformes 7.5 [5.1–9.2] | Sebastinae | Helicolenus dactylopterus | 3 | 1 | [15–17] | 65.7 | 18.2 | 12.2 | 2.6 | 9.2 | |
Scorpaenidae | Scorpaena loppei | 3 | 1 | [91–98] | 73.2 | 20.2 | 1.4 | 4.1 | 5.1 | ||
Triglidae | Chelidonichthys cuculus | 7 | 2 | [17–20] | 69.0 [66.9–71.1] | 19.8 [18.9–20.6] | 6.9 [5.5–8.2] | 2.9 [2.3–3.5] | 8.2 [7.8–8.5] | ||
Perciformes 6.2 [4.8–9.4] | Moronidae | Dicentrarchus labrax | 3 | 1 | [44–48] | 84.1 | 20.2 | 4.5 | 2 | 6 | |
Carangidae | Trachurus trachurus | 30 | 5 | [14–30] | 72.4 [71.1–74.0] | 18.2 [17.3–19.0] | 5 [3.6–6.2] | 3.1 [2.4–4.5] | 6 [5.6–6.5] | ||
Sparidae 8.1 [6.9–9.4] | Spondyliosoma cantharus | 6 | 2 | [17–23] | 69.9 [68.5–71.3] | 18.3 [18.0–18.6] | 6.8 [5.0–8.7] | 2.5 [2.2–2.8] | 6.9 [6.4–7.4] | ||
Boops boops | 9 | 1 | [14–25] | 67 | 19.8 | 5.8 | 2.3 | 8 | |||
Pagellus acarne | 4 | 1 | [15–17] | 65.1 | 19.7 | 10.9 | 2.4 | 9.4 | |||
Mullidae | Mullus surmuletus | 15 | 2 | [11–14] | 71.7 [71.4–71.9] | 18.7 [18.2–19.1] | 4.5 [4.1–4.9] | 2.7 [2.5–2.9] | 6.4 [6.3–6.4] | ||
Cepolidae | Cepola macrophthalma | 6 | 1 | [38–53] | 80.2 | 14.2 | 1.1 | 4.1 | 3.9 | ||
Mugilidae | Liza ramada | 3 | 1 | [33–42] | 67.6 | 23.7 | 3.4 | 3.6 | 6.5 | ||
Labridae | Labrus bergylta | 2 | 1 | [28–32] | 75.8 | 20 | 1.6 | 1.9 | 5.4 | ||
Ammodytidae 5.3 [4.8–5.8] | Hyperoplus lanceolatus | 6 | 1 | [30–37] | 75.1 | 18.1 | 0.9 | 3.2 | 4.8 | ||
Ammodytes tobianus | 9 | 2 | [27–31] | 73.5 [73.5–73.6] | 18.9 [18.9–18.9] | 4.1 [3.8–4.4] | 2 [1.9–2.1] | 5.8 [5.7–5.8] | |||
Trachinidae | Trachinus draco | 5 | 1 | [18–23] | 74.6 | 18.2 | 1.4 | 3.9 | 5.3 | ||
Blenniidae | Paralipophrys trigloides | 16 | 1 | [7–12] | 73.1 | 19.1 | 2 | 3.5 | 5.5 | ||
Callionymidae | Callionymus lyra | 5 | 1 | [15–19] | 75.4 | 17.1 | 2 | 3.6 | 5.2 | ||
Gobiidae | Lesueurigobius friesii | 143 | 1 | [4–6] | 72.4 | 16.5 | 4.1 | 4.8 | 5.6 | ||
Scombridae | Scomber scombrus | 12 | 4 | [25–29] | 67.3 [66.4–69.9] | 17.5 [17.3–17.8] | 10.5 [7.9–13.6] | 2.1 [1.8–2.4] | 7.9 [7.1–8.5] | ||
Pleuronectiformes 5.7 [5.0–6.5] | Scophthalmidae | Lepidorhombus whiffiagonis | 3 | 1 | [21–26] | 73.9 | 18.1 | 3.1 | 2.3 | 6.1 | |
Bothidae | Arnoglossus imperialis | 19 | 1 | [8–14] | 74 | 18.8 | 1.8 | 3.6 | 5.4 | ||
Pleuronectidae 5.7 [5.6–5.8] | Glyptocephalus cynoglossus | 2 | 1 | [29–34] | 76.6 | 17.4 | 3.4 | 2.1 | 5.6 | ||
Microstomus kitt | 2 | 1 | [28–29] | 73.9 | 19.8 | 2.8 | 2.2 | 5.8 | |||
Pleuronectes platessa | 2 | 1 | [27–34] | 74.3 | 17.9 | 3.1 | 3 | 5.8 | |||
Soleidae 5,8 [5–6.5] | Solea solea | 3 | 1 | [28–31] | 77.0 | 18.9 | 1.5 | 2.1 | 5 | ||
Dicologlossa cuneata | 7 | 1 | [12–20] | 69.2 | 21.9 | 3.7 | 3 | 6.5 |
N, number of individuals; n, number of analysed pool. Square brackets indicate the ranges of values. When several species are documented for a family, an order, or a group, mean and range of energy content are provided.
Group . | Order . | Family . | Species . | N . | n . | Length . | Water . | Proteins . | Lipids . | Ash . | Energy . |
---|---|---|---|---|---|---|---|---|---|---|---|
Jellyfish | Semaeostomeae | Ulmaridae | Aurelia aurita | 30 | 1 | [8–12] | 92.1 | 2.1 | 0.3 | 4.2 | 0.7 |
Crustaceans 4.8 [3.4–6.9]* | Eucaria | Euphausiidae | Meganyctiphanes norvegica | 704 | 1 | [2–3] | 77.8 | 15.8 | 1.2 | 3.8 | 3.9 |
Decapoda (macrurans) 4.3 [3.4–5.3] | Oplophoridae | Acanthephyra purpurea | 480 | 1 | [3–6] | 88.4 | 16 | 4.3 | 4.5 | 5.3 | |
Palaemonidae | Palaemon longirostris | 612 | 1 | [1–2] | 82.4 | 11.5 | 1.5 | 2.9 | 3.4 | ||
Pasiphaeidae | Pasiphaea sivado | 342 | 1 | [4–9] | 78.1 | 17.6 | 0.5 | 3.4 | 4.1 | ||
Decapoda (brachyurans) 5.6 [4.2–6.9] | Grapsidae | Pachygrapsus marmoratus | 25 | 1 | [23–40] | 60.1 | 19.9 | 1 | 14.4 | 5.8 | |
Portunidae 5.5 [4.2–6.9] | Polybius henslowii | 37 | 1 | [4–5] | 72.4 | 14.1 | 1.4 | 8.8 | 4.2 | ||
Necora puber | 8 | 1 | [4–7] | 62.8 | 22.8 | 2 | 7.7 | 6.9 | |||
Cephalopods 4.4 [3.8–4.8] | Teuthoidea 4.4 [3.9–4.8] | Loliginidae 4.4 [3.9–4.8] | Allotheutis spp. | 221 | 4 | [3–8] | 78.9 [78.1–80.8] | 16.4 [14.5–16.7] | 1.3 [0.8–1.8] | 1.7 [1.6–2.0] | 3.9 [3.6–4.2] |
Loligo forbesi | 4 | 1 | [10–21] | 76.5 | 17.9 | 2.2 | 2 | 4.6 | |||
Loligo vulgaris | 15 | 5 | [12–25] | 76.2 [75.4–77.0] | 18.9 [18.1–19.6] | 1.5 [0.7–2.2] | 1.7 [1.6–1.9] | 4.8 [4.4–5.3] | |||
Ommastrephidae 4.4 [4.3–4.4] | Illex coindeti | 9 | 3 | [14–17] | 77.8 [77.0–79.2] | 17.3 [15.2–18.7] | 1.9 [1.5–2.2] | 1.6 [1.5–1.8] | 4.3 [4.1–4.4] | ||
Todaropsis eblanae | 9 | 3 | [12–15] | 77.8 [77.7–78.0] | 18 [16.0–19.4] | 2.4 [2.3–2.6] | 1.8 [1.7–1.9] | 4.4 [4.3–4.5] | |||
Sepiolida | Sepiolidae | Sepiola spp. | 77 | 1 | [1–2] | 77.4 | 16 | 2 | 2.6 | 4.8 | |
Sepioidea | Sepiidae | Sepia officinalis | 10 | 2 | [6–10] | 75.8 [75.7–75.9] | 15.8 [15.3–16.4] | 1.2 [1.0–1.4] | 5.5 [5.2–5.8] | 3.8 [3.6–3.9] | |
Octopoda | Octopodidae | Eledone cirrhosa | 3 | 1 | [10–11] | 76 | 16.2 | 2.8 | 2.2 | 4.7 | |
Cartilaginous fish 5.3 [3.9–6.4] | Carcharhiniformes | Scyliorhinidae | Scyliorhinus canicula | 3 | 1 | [48–51] | 72.1 | 22.6 | 5.1 | 2.3 | 6.4 |
Rajiformes | Rajidae | Leucoraja naevus | 3 | 1 | [40–51] | 75.5 | 20.7 | 4.1 | 1.6 | 5.7 | |
Chimaeriformes | Chimaeridae | Chimaera monstrosa | 6 | 1 | [9–10] | 81.3 | 16.4 | 2.2 | 2 | 3.9 | |
Bony fish 5.7 [2.1–10.2] | Anguilliformes 4.5 [2.1–6.9] | Congridae | Conger conger | 3 | 1 | [53–60] | 72.8 | 18.8 | 5.2 | 1.7 | 6.9 |
Serrivomeridae | Serrivomer beanii | 26 | 1 | [21–65] | 78.1 | 8.4 | 1.1 | 2.3 | 2.1 | ||
Clupeiformes 7.8 [5.8–10.1] | Clupeidae 8.5 [6.5–10.1] | Sprattus sprattus | 246 | 4 | [7–13] | 70.9 [69.1–75.4] | 17.2 [16.4–18.2] | 8.2 [3.4–11.2] | 2.5 [2.3–2.7] | 6.5 [4.8–7.3] | |
Sardina pilchardus | 15 | 3 | [14–22] | 65.3 [63.2–67.4] | 17.8 [16.7–19.1] | 11.7 [8.4–17.1] | 2.4 [1.8–3.3] | 8.7 [7.5–10.1] | |||
Clupea harengus | 3 | 1 | [20–20] | 62.8 | 18.6 | 10.7 | 3.6 | 10.2 | |||
Engraulidae | Engraulis encrasicolus | 208 | 4 | [9–13] | 72.0 [69.0–76.0] | 19.6 [18.2–20.3] | 3.4 [1.7–5.2] | 2.8 [1.9–3.2] | 5.8 [4.9–6.7] | ||
Osmeriformes 3.6 [2.6–6.1] | Alepocephalidae | Xenodermichtys copei | 173 | 1 | [4–12] | 87.5 | 9.6 | 0.4 | 2.4 | 2.2 | |
Argentinidae | Argentina sphyraena | 22 | 2 | [11–16] | 72.2 [71.5–72.2] | 17.8 [16.5–19.0] | 5.7 [5.2–6.1] | 2.5 [2.5–2.5] | 6.1 [6.0–6.2] | ||
Platytroctidae | Normichthys operosa | 53 | 1 | [7–16] | 77.2 | 11 | 0.8 | 2.5 | 2.6 | ||
Stomiiformes 3.5 [2.8–4.2] | Sternoptychidae 3.9 [3.5–4.2] | Argyropelecus olfersii | 138 | 1 | [1–10] | 69.2 | 14.8 | 1.3 | 5.3 | 3.5 | |
Maurolicus muelleri | 201 | 1 | [3–5] | 76.3 | 13.5 | 5.2 | 3.7 | 4.2 | |||
Stomiidae | Stomias boa ferox | 28 | 1 | [8–31] | 88.4 | 11.5 | 1.2 | 3.1 | 2.8 | ||
Aulopiformes | Paralepididae | Arctozenus risso | 124 | 1 | [9–20] | 88.4 | 15.8 | 2.5 | 3.4 | 4.3 | |
Myctophiformes 6.6 [4.1–8.6] | Myctophidae 6.6 [4.1–8.6] | Lampanyctus crocodilus | 63 | 1 | [7–15] | 74.7 | 16.1 | 1.6 | 2.9 | 4.1 | |
Benthosema glaciale | 697 | 1 | [2–6] | 85.5 | 13.9 | 7.5 | 3.4 | 5.9 | |||
Notoscopelus kroyeri | 60 | 1 | [3–13] | 87.5 | 16.6 | 11.9 | 2.3 | 7.9 | |||
Lobianchia gemellari | 30 | 1 | [7–9] | 67.1 | 18.8 | 8.6 | 2.1 | 8.6 | |||
Gadiformes 4.7 [3.7–5.5] | Macrouridae | Coelorinchus coelorinchus | 5 | 1 | [8–10] | 77.6 | 16.2 | 2.6 | 3 | 5.1 | |
Gadidae 4.5 [3.9–5.5] | Merlangius merlangus | 24 | 4 | [17–22] | 79.5 [79.3–79.7] | 16.7 [16.6–16.9] | 0.7 [0.3–1.0] | 2.9 [2.3–3.5] | 3.9 [3.8–3.9] | ||
Pollachius pollachius | 2 | 1 | [29–30] | 79 | 17.2 | 0.7 | 2.8 | 4.2 | |||
Micromesistius poutassou | 40 | 4 | [14–20] | 77.9 [77.0–78.3] | 17.4 [16.1–18.1] | 1.5 [1.1–1.7] | 3.1 [2.2–4.0] | 4.4 [4.0–4.7] | |||
Trisopterus luscus | 9 | 3 | [22–26] | 77.3 [76.9–78.2] | 17.7 [16.8–19.2] | 1.8 [1.2–2.3] | 2.9 [1.7–4.2] | 4.7 [4.6–5.0] | |||
Gadiculus argenteus | 23 | 1 | [8–11] | 75.5 | 16.2 | 3.7 | 3.4 | 5 | |||
Trisopterus minutus | 21 | 3 | [14–18] | 73.8 [71.5–75.3] | 18.8 [17.9–20.3] | 2.8 [2.4–3.3] | 3.5 [2.3–4.7] | 5.1 [5.0–5.2] | |||
Gaidropsarus spp. | 5 | 1 | [14–23] | 76.8 | 17.2 | 2.6 | 1.9 | 5.5 | |||
Phycidae | Phycis blennoides | 3 | 1 | [26–28] | 77.5 | 17.4 | 2.5 | 2.7 | 5 | ||
Merlucciidae | Merluccius merluccius | 9 | 3 | [22–29] | 80.4 [79.5–81.2] | 16 [15.1–16.9] | 0.7 [0.3–1.1] | 2.7 [2.2–3.2] | 3.7 [3.4–3.9] | ||
Atheriniformes | Atherinidae | Atherina presbyter | 129 | 3 | [5–12] | 67.8 [65.9–68.8] | 19.8 [18.9–21.2] | 7.3 [6.6–8.1] | 3 [2.1–3.7] | 7.3 [7.1–7.5] | |
Beloniformes 6.0 [5.8–6.2] | Belonidae | Belone belone | 3 | 1 | [55–59] | 74 | 20.1 | 2.9 | 2.7 | 6.2 | |
Scomberesocidae | Scomberesox saurus | 5 | 1 | [25–30] | 71.6 | 22.9 | 2.1 | 2.4 | 5.8 | ||
Beryciformes | Trachichthyidae | Hoplostethus mediterraneus | 17 | 1 | [4–7] | 75.9 | 15.9 | 2.3 | 4.9 | 4.7 | |
Zeiformes | Caproidae | Capros aper | 36 | 1 | [6–7] | 71.3 | 17.2 | 4.8 | 4.6 | 6.2 | |
Syngnathiformes | Syngnathinae | Entelurus aequoreus | 128 | 1 | [25–34] | 73.5 | 14.7 | 1.9 | 6.8 | 4.7 | |
Scorpaeniformes 7.5 [5.1–9.2] | Sebastinae | Helicolenus dactylopterus | 3 | 1 | [15–17] | 65.7 | 18.2 | 12.2 | 2.6 | 9.2 | |
Scorpaenidae | Scorpaena loppei | 3 | 1 | [91–98] | 73.2 | 20.2 | 1.4 | 4.1 | 5.1 | ||
Triglidae | Chelidonichthys cuculus | 7 | 2 | [17–20] | 69.0 [66.9–71.1] | 19.8 [18.9–20.6] | 6.9 [5.5–8.2] | 2.9 [2.3–3.5] | 8.2 [7.8–8.5] | ||
Perciformes 6.2 [4.8–9.4] | Moronidae | Dicentrarchus labrax | 3 | 1 | [44–48] | 84.1 | 20.2 | 4.5 | 2 | 6 | |
Carangidae | Trachurus trachurus | 30 | 5 | [14–30] | 72.4 [71.1–74.0] | 18.2 [17.3–19.0] | 5 [3.6–6.2] | 3.1 [2.4–4.5] | 6 [5.6–6.5] | ||
Sparidae 8.1 [6.9–9.4] | Spondyliosoma cantharus | 6 | 2 | [17–23] | 69.9 [68.5–71.3] | 18.3 [18.0–18.6] | 6.8 [5.0–8.7] | 2.5 [2.2–2.8] | 6.9 [6.4–7.4] | ||
Boops boops | 9 | 1 | [14–25] | 67 | 19.8 | 5.8 | 2.3 | 8 | |||
Pagellus acarne | 4 | 1 | [15–17] | 65.1 | 19.7 | 10.9 | 2.4 | 9.4 | |||
Mullidae | Mullus surmuletus | 15 | 2 | [11–14] | 71.7 [71.4–71.9] | 18.7 [18.2–19.1] | 4.5 [4.1–4.9] | 2.7 [2.5–2.9] | 6.4 [6.3–6.4] | ||
Cepolidae | Cepola macrophthalma | 6 | 1 | [38–53] | 80.2 | 14.2 | 1.1 | 4.1 | 3.9 | ||
Mugilidae | Liza ramada | 3 | 1 | [33–42] | 67.6 | 23.7 | 3.4 | 3.6 | 6.5 | ||
Labridae | Labrus bergylta | 2 | 1 | [28–32] | 75.8 | 20 | 1.6 | 1.9 | 5.4 | ||
Ammodytidae 5.3 [4.8–5.8] | Hyperoplus lanceolatus | 6 | 1 | [30–37] | 75.1 | 18.1 | 0.9 | 3.2 | 4.8 | ||
Ammodytes tobianus | 9 | 2 | [27–31] | 73.5 [73.5–73.6] | 18.9 [18.9–18.9] | 4.1 [3.8–4.4] | 2 [1.9–2.1] | 5.8 [5.7–5.8] | |||
Trachinidae | Trachinus draco | 5 | 1 | [18–23] | 74.6 | 18.2 | 1.4 | 3.9 | 5.3 | ||
Blenniidae | Paralipophrys trigloides | 16 | 1 | [7–12] | 73.1 | 19.1 | 2 | 3.5 | 5.5 | ||
Callionymidae | Callionymus lyra | 5 | 1 | [15–19] | 75.4 | 17.1 | 2 | 3.6 | 5.2 | ||
Gobiidae | Lesueurigobius friesii | 143 | 1 | [4–6] | 72.4 | 16.5 | 4.1 | 4.8 | 5.6 | ||
Scombridae | Scomber scombrus | 12 | 4 | [25–29] | 67.3 [66.4–69.9] | 17.5 [17.3–17.8] | 10.5 [7.9–13.6] | 2.1 [1.8–2.4] | 7.9 [7.1–8.5] | ||
Pleuronectiformes 5.7 [5.0–6.5] | Scophthalmidae | Lepidorhombus whiffiagonis | 3 | 1 | [21–26] | 73.9 | 18.1 | 3.1 | 2.3 | 6.1 | |
Bothidae | Arnoglossus imperialis | 19 | 1 | [8–14] | 74 | 18.8 | 1.8 | 3.6 | 5.4 | ||
Pleuronectidae 5.7 [5.6–5.8] | Glyptocephalus cynoglossus | 2 | 1 | [29–34] | 76.6 | 17.4 | 3.4 | 2.1 | 5.6 | ||
Microstomus kitt | 2 | 1 | [28–29] | 73.9 | 19.8 | 2.8 | 2.2 | 5.8 | |||
Pleuronectes platessa | 2 | 1 | [27–34] | 74.3 | 17.9 | 3.1 | 3 | 5.8 | |||
Soleidae 5,8 [5–6.5] | Solea solea | 3 | 1 | [28–31] | 77.0 | 18.9 | 1.5 | 2.1 | 5 | ||
Dicologlossa cuneata | 7 | 1 | [12–20] | 69.2 | 21.9 | 3.7 | 3 | 6.5 |
Group . | Order . | Family . | Species . | N . | n . | Length . | Water . | Proteins . | Lipids . | Ash . | Energy . |
---|---|---|---|---|---|---|---|---|---|---|---|
Jellyfish | Semaeostomeae | Ulmaridae | Aurelia aurita | 30 | 1 | [8–12] | 92.1 | 2.1 | 0.3 | 4.2 | 0.7 |
Crustaceans 4.8 [3.4–6.9]* | Eucaria | Euphausiidae | Meganyctiphanes norvegica | 704 | 1 | [2–3] | 77.8 | 15.8 | 1.2 | 3.8 | 3.9 |
Decapoda (macrurans) 4.3 [3.4–5.3] | Oplophoridae | Acanthephyra purpurea | 480 | 1 | [3–6] | 88.4 | 16 | 4.3 | 4.5 | 5.3 | |
Palaemonidae | Palaemon longirostris | 612 | 1 | [1–2] | 82.4 | 11.5 | 1.5 | 2.9 | 3.4 | ||
Pasiphaeidae | Pasiphaea sivado | 342 | 1 | [4–9] | 78.1 | 17.6 | 0.5 | 3.4 | 4.1 | ||
Decapoda (brachyurans) 5.6 [4.2–6.9] | Grapsidae | Pachygrapsus marmoratus | 25 | 1 | [23–40] | 60.1 | 19.9 | 1 | 14.4 | 5.8 | |
Portunidae 5.5 [4.2–6.9] | Polybius henslowii | 37 | 1 | [4–5] | 72.4 | 14.1 | 1.4 | 8.8 | 4.2 | ||
Necora puber | 8 | 1 | [4–7] | 62.8 | 22.8 | 2 | 7.7 | 6.9 | |||
Cephalopods 4.4 [3.8–4.8] | Teuthoidea 4.4 [3.9–4.8] | Loliginidae 4.4 [3.9–4.8] | Allotheutis spp. | 221 | 4 | [3–8] | 78.9 [78.1–80.8] | 16.4 [14.5–16.7] | 1.3 [0.8–1.8] | 1.7 [1.6–2.0] | 3.9 [3.6–4.2] |
Loligo forbesi | 4 | 1 | [10–21] | 76.5 | 17.9 | 2.2 | 2 | 4.6 | |||
Loligo vulgaris | 15 | 5 | [12–25] | 76.2 [75.4–77.0] | 18.9 [18.1–19.6] | 1.5 [0.7–2.2] | 1.7 [1.6–1.9] | 4.8 [4.4–5.3] | |||
Ommastrephidae 4.4 [4.3–4.4] | Illex coindeti | 9 | 3 | [14–17] | 77.8 [77.0–79.2] | 17.3 [15.2–18.7] | 1.9 [1.5–2.2] | 1.6 [1.5–1.8] | 4.3 [4.1–4.4] | ||
Todaropsis eblanae | 9 | 3 | [12–15] | 77.8 [77.7–78.0] | 18 [16.0–19.4] | 2.4 [2.3–2.6] | 1.8 [1.7–1.9] | 4.4 [4.3–4.5] | |||
Sepiolida | Sepiolidae | Sepiola spp. | 77 | 1 | [1–2] | 77.4 | 16 | 2 | 2.6 | 4.8 | |
Sepioidea | Sepiidae | Sepia officinalis | 10 | 2 | [6–10] | 75.8 [75.7–75.9] | 15.8 [15.3–16.4] | 1.2 [1.0–1.4] | 5.5 [5.2–5.8] | 3.8 [3.6–3.9] | |
Octopoda | Octopodidae | Eledone cirrhosa | 3 | 1 | [10–11] | 76 | 16.2 | 2.8 | 2.2 | 4.7 | |
Cartilaginous fish 5.3 [3.9–6.4] | Carcharhiniformes | Scyliorhinidae | Scyliorhinus canicula | 3 | 1 | [48–51] | 72.1 | 22.6 | 5.1 | 2.3 | 6.4 |
Rajiformes | Rajidae | Leucoraja naevus | 3 | 1 | [40–51] | 75.5 | 20.7 | 4.1 | 1.6 | 5.7 | |
Chimaeriformes | Chimaeridae | Chimaera monstrosa | 6 | 1 | [9–10] | 81.3 | 16.4 | 2.2 | 2 | 3.9 | |
Bony fish 5.7 [2.1–10.2] | Anguilliformes 4.5 [2.1–6.9] | Congridae | Conger conger | 3 | 1 | [53–60] | 72.8 | 18.8 | 5.2 | 1.7 | 6.9 |
Serrivomeridae | Serrivomer beanii | 26 | 1 | [21–65] | 78.1 | 8.4 | 1.1 | 2.3 | 2.1 | ||
Clupeiformes 7.8 [5.8–10.1] | Clupeidae 8.5 [6.5–10.1] | Sprattus sprattus | 246 | 4 | [7–13] | 70.9 [69.1–75.4] | 17.2 [16.4–18.2] | 8.2 [3.4–11.2] | 2.5 [2.3–2.7] | 6.5 [4.8–7.3] | |
Sardina pilchardus | 15 | 3 | [14–22] | 65.3 [63.2–67.4] | 17.8 [16.7–19.1] | 11.7 [8.4–17.1] | 2.4 [1.8–3.3] | 8.7 [7.5–10.1] | |||
Clupea harengus | 3 | 1 | [20–20] | 62.8 | 18.6 | 10.7 | 3.6 | 10.2 | |||
Engraulidae | Engraulis encrasicolus | 208 | 4 | [9–13] | 72.0 [69.0–76.0] | 19.6 [18.2–20.3] | 3.4 [1.7–5.2] | 2.8 [1.9–3.2] | 5.8 [4.9–6.7] | ||
Osmeriformes 3.6 [2.6–6.1] | Alepocephalidae | Xenodermichtys copei | 173 | 1 | [4–12] | 87.5 | 9.6 | 0.4 | 2.4 | 2.2 | |
Argentinidae | Argentina sphyraena | 22 | 2 | [11–16] | 72.2 [71.5–72.2] | 17.8 [16.5–19.0] | 5.7 [5.2–6.1] | 2.5 [2.5–2.5] | 6.1 [6.0–6.2] | ||
Platytroctidae | Normichthys operosa | 53 | 1 | [7–16] | 77.2 | 11 | 0.8 | 2.5 | 2.6 | ||
Stomiiformes 3.5 [2.8–4.2] | Sternoptychidae 3.9 [3.5–4.2] | Argyropelecus olfersii | 138 | 1 | [1–10] | 69.2 | 14.8 | 1.3 | 5.3 | 3.5 | |
Maurolicus muelleri | 201 | 1 | [3–5] | 76.3 | 13.5 | 5.2 | 3.7 | 4.2 | |||
Stomiidae | Stomias boa ferox | 28 | 1 | [8–31] | 88.4 | 11.5 | 1.2 | 3.1 | 2.8 | ||
Aulopiformes | Paralepididae | Arctozenus risso | 124 | 1 | [9–20] | 88.4 | 15.8 | 2.5 | 3.4 | 4.3 | |
Myctophiformes 6.6 [4.1–8.6] | Myctophidae 6.6 [4.1–8.6] | Lampanyctus crocodilus | 63 | 1 | [7–15] | 74.7 | 16.1 | 1.6 | 2.9 | 4.1 | |
Benthosema glaciale | 697 | 1 | [2–6] | 85.5 | 13.9 | 7.5 | 3.4 | 5.9 | |||
Notoscopelus kroyeri | 60 | 1 | [3–13] | 87.5 | 16.6 | 11.9 | 2.3 | 7.9 | |||
Lobianchia gemellari | 30 | 1 | [7–9] | 67.1 | 18.8 | 8.6 | 2.1 | 8.6 | |||
Gadiformes 4.7 [3.7–5.5] | Macrouridae | Coelorinchus coelorinchus | 5 | 1 | [8–10] | 77.6 | 16.2 | 2.6 | 3 | 5.1 | |
Gadidae 4.5 [3.9–5.5] | Merlangius merlangus | 24 | 4 | [17–22] | 79.5 [79.3–79.7] | 16.7 [16.6–16.9] | 0.7 [0.3–1.0] | 2.9 [2.3–3.5] | 3.9 [3.8–3.9] | ||
Pollachius pollachius | 2 | 1 | [29–30] | 79 | 17.2 | 0.7 | 2.8 | 4.2 | |||
Micromesistius poutassou | 40 | 4 | [14–20] | 77.9 [77.0–78.3] | 17.4 [16.1–18.1] | 1.5 [1.1–1.7] | 3.1 [2.2–4.0] | 4.4 [4.0–4.7] | |||
Trisopterus luscus | 9 | 3 | [22–26] | 77.3 [76.9–78.2] | 17.7 [16.8–19.2] | 1.8 [1.2–2.3] | 2.9 [1.7–4.2] | 4.7 [4.6–5.0] | |||
Gadiculus argenteus | 23 | 1 | [8–11] | 75.5 | 16.2 | 3.7 | 3.4 | 5 | |||
Trisopterus minutus | 21 | 3 | [14–18] | 73.8 [71.5–75.3] | 18.8 [17.9–20.3] | 2.8 [2.4–3.3] | 3.5 [2.3–4.7] | 5.1 [5.0–5.2] | |||
Gaidropsarus spp. | 5 | 1 | [14–23] | 76.8 | 17.2 | 2.6 | 1.9 | 5.5 | |||
Phycidae | Phycis blennoides | 3 | 1 | [26–28] | 77.5 | 17.4 | 2.5 | 2.7 | 5 | ||
Merlucciidae | Merluccius merluccius | 9 | 3 | [22–29] | 80.4 [79.5–81.2] | 16 [15.1–16.9] | 0.7 [0.3–1.1] | 2.7 [2.2–3.2] | 3.7 [3.4–3.9] | ||
Atheriniformes | Atherinidae | Atherina presbyter | 129 | 3 | [5–12] | 67.8 [65.9–68.8] | 19.8 [18.9–21.2] | 7.3 [6.6–8.1] | 3 [2.1–3.7] | 7.3 [7.1–7.5] | |
Beloniformes 6.0 [5.8–6.2] | Belonidae | Belone belone | 3 | 1 | [55–59] | 74 | 20.1 | 2.9 | 2.7 | 6.2 | |
Scomberesocidae | Scomberesox saurus | 5 | 1 | [25–30] | 71.6 | 22.9 | 2.1 | 2.4 | 5.8 | ||
Beryciformes | Trachichthyidae | Hoplostethus mediterraneus | 17 | 1 | [4–7] | 75.9 | 15.9 | 2.3 | 4.9 | 4.7 | |
Zeiformes | Caproidae | Capros aper | 36 | 1 | [6–7] | 71.3 | 17.2 | 4.8 | 4.6 | 6.2 | |
Syngnathiformes | Syngnathinae | Entelurus aequoreus | 128 | 1 | [25–34] | 73.5 | 14.7 | 1.9 | 6.8 | 4.7 | |
Scorpaeniformes 7.5 [5.1–9.2] | Sebastinae | Helicolenus dactylopterus | 3 | 1 | [15–17] | 65.7 | 18.2 | 12.2 | 2.6 | 9.2 | |
Scorpaenidae | Scorpaena loppei | 3 | 1 | [91–98] | 73.2 | 20.2 | 1.4 | 4.1 | 5.1 | ||
Triglidae | Chelidonichthys cuculus | 7 | 2 | [17–20] | 69.0 [66.9–71.1] | 19.8 [18.9–20.6] | 6.9 [5.5–8.2] | 2.9 [2.3–3.5] | 8.2 [7.8–8.5] | ||
Perciformes 6.2 [4.8–9.4] | Moronidae | Dicentrarchus labrax | 3 | 1 | [44–48] | 84.1 | 20.2 | 4.5 | 2 | 6 | |
Carangidae | Trachurus trachurus | 30 | 5 | [14–30] | 72.4 [71.1–74.0] | 18.2 [17.3–19.0] | 5 [3.6–6.2] | 3.1 [2.4–4.5] | 6 [5.6–6.5] | ||
Sparidae 8.1 [6.9–9.4] | Spondyliosoma cantharus | 6 | 2 | [17–23] | 69.9 [68.5–71.3] | 18.3 [18.0–18.6] | 6.8 [5.0–8.7] | 2.5 [2.2–2.8] | 6.9 [6.4–7.4] | ||
Boops boops | 9 | 1 | [14–25] | 67 | 19.8 | 5.8 | 2.3 | 8 | |||
Pagellus acarne | 4 | 1 | [15–17] | 65.1 | 19.7 | 10.9 | 2.4 | 9.4 | |||
Mullidae | Mullus surmuletus | 15 | 2 | [11–14] | 71.7 [71.4–71.9] | 18.7 [18.2–19.1] | 4.5 [4.1–4.9] | 2.7 [2.5–2.9] | 6.4 [6.3–6.4] | ||
Cepolidae | Cepola macrophthalma | 6 | 1 | [38–53] | 80.2 | 14.2 | 1.1 | 4.1 | 3.9 | ||
Mugilidae | Liza ramada | 3 | 1 | [33–42] | 67.6 | 23.7 | 3.4 | 3.6 | 6.5 | ||
Labridae | Labrus bergylta | 2 | 1 | [28–32] | 75.8 | 20 | 1.6 | 1.9 | 5.4 | ||
Ammodytidae 5.3 [4.8–5.8] | Hyperoplus lanceolatus | 6 | 1 | [30–37] | 75.1 | 18.1 | 0.9 | 3.2 | 4.8 | ||
Ammodytes tobianus | 9 | 2 | [27–31] | 73.5 [73.5–73.6] | 18.9 [18.9–18.9] | 4.1 [3.8–4.4] | 2 [1.9–2.1] | 5.8 [5.7–5.8] | |||
Trachinidae | Trachinus draco | 5 | 1 | [18–23] | 74.6 | 18.2 | 1.4 | 3.9 | 5.3 | ||
Blenniidae | Paralipophrys trigloides | 16 | 1 | [7–12] | 73.1 | 19.1 | 2 | 3.5 | 5.5 | ||
Callionymidae | Callionymus lyra | 5 | 1 | [15–19] | 75.4 | 17.1 | 2 | 3.6 | 5.2 | ||
Gobiidae | Lesueurigobius friesii | 143 | 1 | [4–6] | 72.4 | 16.5 | 4.1 | 4.8 | 5.6 | ||
Scombridae | Scomber scombrus | 12 | 4 | [25–29] | 67.3 [66.4–69.9] | 17.5 [17.3–17.8] | 10.5 [7.9–13.6] | 2.1 [1.8–2.4] | 7.9 [7.1–8.5] | ||
Pleuronectiformes 5.7 [5.0–6.5] | Scophthalmidae | Lepidorhombus whiffiagonis | 3 | 1 | [21–26] | 73.9 | 18.1 | 3.1 | 2.3 | 6.1 | |
Bothidae | Arnoglossus imperialis | 19 | 1 | [8–14] | 74 | 18.8 | 1.8 | 3.6 | 5.4 | ||
Pleuronectidae 5.7 [5.6–5.8] | Glyptocephalus cynoglossus | 2 | 1 | [29–34] | 76.6 | 17.4 | 3.4 | 2.1 | 5.6 | ||
Microstomus kitt | 2 | 1 | [28–29] | 73.9 | 19.8 | 2.8 | 2.2 | 5.8 | |||
Pleuronectes platessa | 2 | 1 | [27–34] | 74.3 | 17.9 | 3.1 | 3 | 5.8 | |||
Soleidae 5,8 [5–6.5] | Solea solea | 3 | 1 | [28–31] | 77.0 | 18.9 | 1.5 | 2.1 | 5 | ||
Dicologlossa cuneata | 7 | 1 | [12–20] | 69.2 | 21.9 | 3.7 | 3 | 6.5 |
N, number of individuals; n, number of analysed pool. Square brackets indicate the ranges of values. When several species are documented for a family, an order, or a group, mean and range of energy content are provided.
Results
The proximate composition of the 78 forage species analysed varied largely between species (Table 1). As expected, water represented the main component, with ∼75% of body mass (75.1 ± 6.2%; range 60.1–92.1%). Ash represented 1.6–14.4% and was low and relatively constant across most species (Figure 1d), highest values (>5%) being observed in brachyuran crustaceans (7.7–14.4%), snake pipefish (6.8%), and cuttlefish (Sepia officinalis; 5.5%). Protein represented the second most important component after water (17.3 ± 3.3%; range 2.1–23.7%). Most values ranged from 15 to 20% (Figure 1b). A few species yielded a relatively high protein content, e.g. the swimming crab (Necora puber; 22.8%), the teleosts Scomberesox saurus (22.9%) and Liza ramada (23.7%). In contrast, values of protein were lowest in jellyfish (Aurelia aurita; 2.1%), the mesopelagic teleosts Serrivomer beanii (8.4%) and Xenodermichthys copei (9.6%), and the shrimp Palaemon longirostris (11.5%). Lipids were highly variable, ranging from 0.3 to 12.2% (Figure 1c). Only 15% of forage species had lipid contents >6% of wet body mass, and the species with greatest lipid content were the pelagic teleosts Scomber scombrus (10.5%) and Sardina pilchardus (11.7%), and the epibenthic scorpaenid Helicolenus dactylopterus (12.2%).
Energy density of forage species ranged from 0.7 to 10.2 kJ g−1 (Figure 1e). Lipid contents explained most of the variation in energy content (r2 = 0.761; Figure 2), residuals being explained mainly by protein variability (r2 = 0.652; Figure 3). Three classes of prey quality can be designated, therefore, according to the values of energy density (Table 2): low-quality species (<4 kJ g−1), including S. beanii (2.1 kJ g−1), X. copei (2.2 kJ g−1), and P. longirostris (3.4 kJ g−1), moderate-quality species (4 < ED < 6 kJ g−1), encompassing the majority of the species considered here, and high-quality species (>6 kJ g−1), including species such as Notoscopelus kroyeri (7.9 kJ g−1), S. pilchardus (8.7 kJ g−1), and Pagellus acarne (9.4 kJ g−1).
Low-quality species . | Moderate-quality species . | High-quality species . |
---|---|---|
Jellyfish | Crustaceans | Crustaceans |
Crustaceans | Oplophoridae | Some Portunidae |
Euphausiidae | Pasiphaeidae | Necora |
Palaemonidae | Some Portunidae | Cartilaginous fish |
Cephalopods | Polybius | Scyliorhinidae |
Sepiidae | Grapsidae | Bony fish |
Cartilaginous fish | Cephalopods | Argentinidae |
Chimaeridae | Loliginidae | Atherinidae |
Bony fish | Ommastrephidae | Belonidae |
Alepocephalidae | Sepiolidae | Caproidae |
Cepolidae | Octopodidae | Carangidae |
Merlucciidae | Cartilaginous fish | Clupeidae |
Platytroctidae | Rajidae | Engraulidae |
Serrivomeridae | Bony fish | Moronidae |
Some Sternoptychidae | Ammodytidae | Mugilidae |
Argyropelecus | Blenniidae | Mullidae |
Stomiidae | Bothidae | Some Myctophidae |
Callionymidae | Notoscopelus | |
Gadidae | Lobianchia | |
Labridae | Scombridae | |
Macrouridae | Scophthalmidae | |
Some Myctophidae | Sebastinae | |
Lampanyctus | Some Soleidae | |
Benthosema | Dicologlossa | |
Paralepididae | Sparidae | |
Phycidae | Triglidae | |
Pleuronectidae | ||
Scomberesocidae | ||
Scorpaenidae | ||
Some Soleidae | ||
Solea | ||
Some Sternoptychidae | ||
Maurolicus | ||
Syngnathinae | ||
Trachichthyidae | ||
Trachinidae |
Low-quality species . | Moderate-quality species . | High-quality species . |
---|---|---|
Jellyfish | Crustaceans | Crustaceans |
Crustaceans | Oplophoridae | Some Portunidae |
Euphausiidae | Pasiphaeidae | Necora |
Palaemonidae | Some Portunidae | Cartilaginous fish |
Cephalopods | Polybius | Scyliorhinidae |
Sepiidae | Grapsidae | Bony fish |
Cartilaginous fish | Cephalopods | Argentinidae |
Chimaeridae | Loliginidae | Atherinidae |
Bony fish | Ommastrephidae | Belonidae |
Alepocephalidae | Sepiolidae | Caproidae |
Cepolidae | Octopodidae | Carangidae |
Merlucciidae | Cartilaginous fish | Clupeidae |
Platytroctidae | Rajidae | Engraulidae |
Serrivomeridae | Bony fish | Moronidae |
Some Sternoptychidae | Ammodytidae | Mugilidae |
Argyropelecus | Blenniidae | Mullidae |
Stomiidae | Bothidae | Some Myctophidae |
Callionymidae | Notoscopelus | |
Gadidae | Lobianchia | |
Labridae | Scombridae | |
Macrouridae | Scophthalmidae | |
Some Myctophidae | Sebastinae | |
Lampanyctus | Some Soleidae | |
Benthosema | Dicologlossa | |
Paralepididae | Sparidae | |
Phycidae | Triglidae | |
Pleuronectidae | ||
Scomberesocidae | ||
Scorpaenidae | ||
Some Soleidae | ||
Solea | ||
Some Sternoptychidae | ||
Maurolicus | ||
Syngnathinae | ||
Trachichthyidae | ||
Trachinidae |
Low-quality species . | Moderate-quality species . | High-quality species . |
---|---|---|
Jellyfish | Crustaceans | Crustaceans |
Crustaceans | Oplophoridae | Some Portunidae |
Euphausiidae | Pasiphaeidae | Necora |
Palaemonidae | Some Portunidae | Cartilaginous fish |
Cephalopods | Polybius | Scyliorhinidae |
Sepiidae | Grapsidae | Bony fish |
Cartilaginous fish | Cephalopods | Argentinidae |
Chimaeridae | Loliginidae | Atherinidae |
Bony fish | Ommastrephidae | Belonidae |
Alepocephalidae | Sepiolidae | Caproidae |
Cepolidae | Octopodidae | Carangidae |
Merlucciidae | Cartilaginous fish | Clupeidae |
Platytroctidae | Rajidae | Engraulidae |
Serrivomeridae | Bony fish | Moronidae |
Some Sternoptychidae | Ammodytidae | Mugilidae |
Argyropelecus | Blenniidae | Mullidae |
Stomiidae | Bothidae | Some Myctophidae |
Callionymidae | Notoscopelus | |
Gadidae | Lobianchia | |
Labridae | Scombridae | |
Macrouridae | Scophthalmidae | |
Some Myctophidae | Sebastinae | |
Lampanyctus | Some Soleidae | |
Benthosema | Dicologlossa | |
Paralepididae | Sparidae | |
Phycidae | Triglidae | |
Pleuronectidae | ||
Scomberesocidae | ||
Scorpaenidae | ||
Some Soleidae | ||
Solea | ||
Some Sternoptychidae | ||
Maurolicus | ||
Syngnathinae | ||
Trachichthyidae | ||
Trachinidae |
Low-quality species . | Moderate-quality species . | High-quality species . |
---|---|---|
Jellyfish | Crustaceans | Crustaceans |
Crustaceans | Oplophoridae | Some Portunidae |
Euphausiidae | Pasiphaeidae | Necora |
Palaemonidae | Some Portunidae | Cartilaginous fish |
Cephalopods | Polybius | Scyliorhinidae |
Sepiidae | Grapsidae | Bony fish |
Cartilaginous fish | Cephalopods | Argentinidae |
Chimaeridae | Loliginidae | Atherinidae |
Bony fish | Ommastrephidae | Belonidae |
Alepocephalidae | Sepiolidae | Caproidae |
Cepolidae | Octopodidae | Carangidae |
Merlucciidae | Cartilaginous fish | Clupeidae |
Platytroctidae | Rajidae | Engraulidae |
Serrivomeridae | Bony fish | Moronidae |
Some Sternoptychidae | Ammodytidae | Mugilidae |
Argyropelecus | Blenniidae | Mullidae |
Stomiidae | Bothidae | Some Myctophidae |
Callionymidae | Notoscopelus | |
Gadidae | Lobianchia | |
Labridae | Scombridae | |
Macrouridae | Scophthalmidae | |
Some Myctophidae | Sebastinae | |
Lampanyctus | Some Soleidae | |
Benthosema | Dicologlossa | |
Paralepididae | Sparidae | |
Phycidae | Triglidae | |
Pleuronectidae | ||
Scomberesocidae | ||
Scorpaenidae | ||
Some Soleidae | ||
Solea | ||
Some Sternoptychidae | ||
Maurolicus | ||
Syngnathinae | ||
Trachichthyidae | ||
Trachinidae |
Discussion
With 78 species analysed, the present study is the first to examine proximate composition and quality of forage species in the NE Atlantic across such a broad variety of taxa, including jellyfish, crustaceans, cephalopods, and cartilaginous and bony fish. Among fish species, all habitats were covered; benthic, demersal, neritic pelagic, and oceanic pelagic. The results showed broad variations in proximate composition and quality between species. Lipids were the most structuring component and were determined largely by prey quality. Therefore, with energy densities ranging from 2 to 10 kJ g−1, the quality of forage species was heterogeneous, and we propose three classes of quality of species; low (<4 kJ g−1), moderate (4 < ED < 6 kJ g−1), and high quality (>6 kJ g−1). Across the taxa studied, some 20% were classified as low-quality species, 50% as species of moderate quality, and 30% as species of high quality. Only a few species had an energy value >8 kJ g−1.
Within-species variations in proximate composition and energy content could not be investigated in full. Parameters such as year, season, maturity, and age could influence energy values (Anthony et al., 2000; Van de Putte et al., 2006). In this study, up to several hundred specimens per species were pooled (Table 1) to smooth intraspecific variability, and almost all specimens were sampled in the same season. Therefore, the hierarchy proposed was consistent with previous results worldwide, with some fat and high-energy density families such as clupeids or myctophids opposite to lean and low-to-moderate-energy density families, such as gadids or squids (Anthony et al., 2000; Eder and Lewis, 2005). However, more samples are needed to document intraspecific variations in proximate composition and energy content, especially for fat species which could have notable seasonal variations (Dubreuil and Petitgas, 2009). Moreover, it must be acknowledged that forage species body composition and energy content are not the only variables required to describe prey profitability intrinsically. For example, prey swimming speed, dispersion, encounter rate, and non-energy-related nutritional aspects of the diet need to be taken into account for a full evaluation of the profitability of a given prey to a given predator.
Despite these reservations, it is clear that in the NE Atlantic, prey profitability for a predator assessed from energy densities can differ largely between species. All forage species, even when morphologically or taxonomically similar, cannot be considered as equivalent and interchangeable for the fulfilments of predator energy and food requirements. In the context of low-quality prey expansion in marine ecosystems (Österblom et al., 2008), this study provides baseline data for evaluating any possible effects of regime shifts associated with changes in forage species availability.
Finally, the heterogeneity of forage-species quality needs to be considered in ecosystem modelling. Intermediate and lower trophic levels are often represented by multispecies boxes within models defined merely by size and general ecological profile, e.g. mesopelagic fish, small demersal fish, or large oceanic squid (Morissette et al., 2006; Chen et al., 2008). The results here highlight the fact that some combination of species within the same box in a model can be inconsistent when defined solely on habitat and size similarity. For instance, mesopelagic fish including myctophids and alepocephalids, or demersal fish including triglids and phycids are heterogeneous groupings in terms of body composition and energy content. Such species types are not equally valuable to, or even looked for by, top predators. It is therefore proposed that in models of pelagic ecosystems, multispecific compartments of forage organisms be defined with the aim of maximizing within-compartment homogeneity in body composition, energy content, and ultimately profitability to top predators.
Acknowledgements
The work was part of a larger research programme on the role and the dietary preferences of top predators in the Bay of Biscay and adjacent Atlantic areas. We are particularly grateful to J-C. Mahé, R. Bellail, J-C. Poulard, and J-P. Leaute (Ifremer), and the crew of the RV “Thalassa” for their support during EVHOE cruises, and also to additional samplers S. Dixneuf, J. Moderan, and G. Radenac. The proximate composition and prey densities evaluations were carried out by E. Bodin and M. Castin (LASAT), whose time and competence are gratefully acknowledged. The Centre de Recherche sur les Mammifères Marins was funded by the Ministère de l'Ecologie et du Développement Durable and the Communauté d'Agglomération de la Ville de La Rochelle. Part of the work was supported by EU Project FACTS (FPVII: Contract 244966). The PhD thesis of JS is supported by the Agence Nationale de la Recherche Technique with a CIFRE grant. Finally, we thank the editor Bill Turrell for his comments that allowed us to improve the quality of the manuscript.