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Table 1 Diet composition of T. thynnus and dietary indexes calculated for each prey item: abundance percentage (%N), weight percentage (%W), frequency of occurrence (%F), index of relative abundance (IRI), IRI percentage (%IRI)

From: Feeding habits of the Atlantic bluefin tuna, Thunnus thynnus (L. 1758), in the central Mediterranean Sea (Strait of Messina)

Class and order Family Species %N %W %F IRI %IRI
Hydrozoa
Siphonophora Diphyidae Diphyidae unid. 0.503 0.002 8.929 4.514 0.135
Crustacea
Amphipoda Phronimidae Phronima sedentaria (Forskal, 1775) 0.344 0.009 3.571 1.263 0.038
Phrosinidae Phrosina semilunata (Risso, 1882) 0.212 0.009 4.464 0.984 0.030
Platyscelidae Platyscelus ovoides (Risso, 1816) 0.053 0.002 1.786 0.098 0.003
Lycaeidae Lycaeidae unid. 0.424 0.000 0.893 0.379 0.011
Copepoda   Copepoda unid. 0.026 0.000 0.893 0.024 0.001
Decapoda Aristeidae Aristaeomorpha foliacea (Risso, 1827) 0.026 0.144 0.893 0.152 0.005
Benthesicymidae Gennadas elegans (Smith, 1882) 0.026 0.002 0.893 0.025 0.001
Sergestidae Sergestes corniculum (Kroyer, 1855) 19.439 1.270 15.179 314.331 9.433
Sergestes robustus (Smith, 1882) 16.552 1.671 16.964 309.138 9.277
Oplophoridae Acanthephyra purpurea (Milne-Edwards, 1881) 0.026 0.003 0.893 0.027 0.001
Pasiphaeidae Pasiphaea multidentata (Esmark, 1866) 0.662 0.071 5.357 3.927 0.118
Pasiphaea sivado (Risso, 1816) 0.079 0.012 1.786 0.164 0.005
Pasiphaea sp. 0.132 0.005 1.786 0.246 0.007
Crustacea unid. 0.026 0.000 0.893 0.024 0.001
Cephalopoda
Sepiolida Sepiolidae Heteroteuthis dispar (Rüppell, 1844) 0.477 0.161 7.143 4.555 0.137
Teuthida Brachioteuthidae Brachioteuthis riisei (Steenstrup, 1882) 0.026 0.013 0.893 0.036 0.001
Cranchiidae Galiteuthis armata (Joubin, 1898) 0.026 0.006 0.893 0.029 0.001
Thysanoteuthidae Thysanoteuthis rhombus (Troschel, 1857) 0.026 5.651 0.893 5.069 0.152
Enoploteuthidae Abralia veranyi (Férussac, 1835) 0.238 0.149 3.571 1.384 0.042
Abraliopsis morisii (Vérany, 1839). 0.106 0.011 1.786 0.210 0.006
Pyroteuthidae Pyroteuthis margaritifera (Ruppell, 1844) 0.053 0.006 0.893 0.053 0.002
Onycoteuthidae Onychoteuthis banksii (Leach, 1817) 0.556 0.298 7.143 6.102 0.183
Ancistroteuthis lichtensteinii (Férussac, 1835) 0.053 0.030 1.786 0.148 0.004
Ommastrephidae Ommastrephes bartramii (Lesueur, 1821) 1.033 1.723 7.143 19.686 0.591
Illex coindetii (Vérany, 1839) 2.860 11.200 33.929 477.055 14.316
Todarodes sagittatus (Lamarck, 1798) 0.477 2.305 7.143 19.867 0.596
Histioteuthidae Histioteuthis bonnellii (Férussac, 1835) 0.821 2.166 8.929 26.669 0.800
Histioteuthis reversa (Verrill, 1880) 0.053 0.606 1.786 1.177 0.035
Octopoteuthidae Octopoteuthis sicula Rüppell, 1844 0.026 0.015 0.893 0.037 0.001
Chiroteuthidae Chiroteuthis veranyi (Férussac, 1835) 0.079 0.458 2.679 1.439 0.043
  Teuthida unid. 0.026 0.002 0.893 0.026 0.001
Myopsida Loliginidae Loligo vulgaris Lamarck, 1798 0.026 0.007 0.893 0.030 0.001
Octopoda Argonautidae Argonauta argo Linnaeus, 1758 0.212 0.272 5.357 2.590 0.078
Cephalopoda unid. 0.159 0.024 5.357 0.979 0.029
Tunicata
Salpida   Salpida ind 0.583 0.043 1.786 1.117 0.034
  Pyrosomatidae Pyrosoma atlanticum Péron, 1804 0.132 0.033 0.893 0.147 0.004
Doliolida Doliolidae Doliolum sp. 1.033 0.067 5.357 5.890 0.177
Teleostea
Aulopiformes Paralepididae Paralepis coregonoides Risso, 1820 0.053 0.005 1.786 0.104 0.003
Paralepis speciosa Bellotti, 1878 0.026 0.010 0.893 0.032 0.001
Sudis hyalina Rafinesque, 1810 0.079 0.029 2.679 0.290 0.009
Arctozenus risso (Bonaparte, 1840) 0.079 0.022 2.679 0.272 0.008
Paralepididae unid. 0.026 0.015 0.893 0.037 0.001
Clupeiformes Clupeidae Sardinella aurita (Valenciennes, 1847) 0.106 2.476 2.679 6.917 0.208
Perciformes Carangidae Caranx crysos (Geoffroy Saint Hilaire, 1809) 0.026 3.113 0.893 2.803 0.084
Trachurus picturatus (Bowdich, 1825) 0.318 11.167 7.143 82.033 2.462
Trachurus mediterraneus (Steindachner, 1868) 0.053 0.028 1.786 0.145 0.004
Trachurus sp. 0.079 0.131 0.893 0.188 0.006
Carangidae unid. 0.026 1.161 0.893 1.061 0.032
Centracanthidae Spicara maena (Linnaeus, 1758) 0.053 0.261 1.786 0.560 0.017
Centrolophidae Centrolophus niger (Gmelin, 1788) 0.026 0.020 0.893 0.041 0.001
Schedophilus medusophagus (Cocco, 1839) 0.026 0.027 0.893 0.048 0.001
Nomeidae Cubiceps gracilis (Lowe, 1843) 0.026 0.024 0.893 0.045 0.001
Scombridae Auxis rochei (Risso, 1810) 0.026 4.320 0.893 3.881 0.116
Sarda sarda (Bloch, 1793) 0.026 4.213 0.893 3.786 0.114
Scomber japonicus (Gmelin, 1789) 0.026 0.662 0.893 0.614 0.018
Sparidae Boops boops (Linnaeus, 1758) 0.344 3.934 5.357 22.918 0.688
Dentex gibbosus (Rafinesque, 1810) 0.026 0.629 0.893 0.585 0.018
Sarpa Salpa (Linnaeus, 1758) 0.026 1.393 0.893 1.268 0.038
Sparidae unid. 0.132 0.074 3.571 0.736 0.022
Trichiuridae Lepidopus caudatus (Euphrasen, 1788) 0.106 1.154 2.679 3.376 0.101
Beloniformes Belonidae Belone belone gracilis (Linnaeus, 1761) 0.026 0.005 0.893 0.028 0.001
Scomberesocidae Scomberesox saurus (Walbaum, 1792) 0.265 0.134 3.571 1.426 0.043
Stomiiformes Gonostomatidae Gonostoma denudatum Rafinesque, 1810 0.053 0.068 1.786 0.216 0.006
Phosichthyidae Ichthyococcus ovatus (Cocco, 1838) 0.106 0.011 0.893 0.105 0.003
Vinciguerria attenuata (Cocco, 1838) 0.715 0.022 7.143 5.263 0.158
Vinciguerria poweriae (Cocco, 1838) 0.079 0.027 1.786 0.190 0.006
Sternoptychidae Argyropelecus hemygimnus Cocco, 1829 0.079 0.023 1.786 0.182 0.005
Maurolicus muelleri Gmelin, 1789 0.715 0.224 14.286 13.411 0.402
Stomiidae Chauliodus sloani Bloch & Schneider, 1810 10.832 13.711 20.536 504.003 15.124
Stomias boa boa (Risso, 1810) 0.079 0.032 2.679 0.298 0.009
Myctophiformes Myctophidae Benthosema glaciale (Reinhardt, 1837) 1.377 0.344 7.143 12.296 0.369
Ceratoscopelus maderensis (Lowe, 1839) 8.316 2.317 36.607 389.215 11.680
Diaphus holti Tåning, 1918 1.457 0.265 12.500 21.525 0.646
Electrona risso Cocco, 1829 1.192 0.292 6.250 9.276 0.278
Hygophum benoiti (Cocco, 1838) 15.810 4.994 36.607 761.597 22.854
Hygophum hygomii (Lütken, 1892) 0.980 0.073 8.929 9.398 0.282
Lampanyctus crocodilus Risso, 1810 0.900 0.531 6.250 8.950 0.269
Lampanyctus pusillus (Johnson, 1890) 0.265 0.026 3.571 1.039 0.031
Myctophum punctatum Rafinesque, 1810 3.708 1.272 25.893 128.946 3.869
Notoscopelus elongatus (Costa, 1844) 1.536 0.237 9.821 17.415 0.523
Symbolophorus veranyi (Moreau, 1888) 0.026 0.031 0.893 0.051 0.002
Zeiformes Caproidae Capros aper (Linnaeus, 1758) 0.344 1.870 1.786 3.955 0.119
Gadiformes Gadidae Micromesistius poutassou (Risso, 1827) 0.053 0.253 0.893 0.273 0.008
Merluccidae Merluccius merluccius (Linnaeus, 1758) 0.026 0.122 0.893 0.132 0.004
Anguilliformes Anguillidae Anguilla anguilla (Linnaeus, 1758) 0.662 9.558 8.929 91.247 2.738
Osmeiformes Microstomatidae Microstoma microstoma (Risso, 1810) 0.106 0.126 2.679 0.620 0.019
Nansenia oblita (Facciolà, 1887) 0.053 0.011 1.786 0.114 0.003
Teleostea unid. 0.900 0.106 9.821 9.880 0.296
  1. Unid. unidentified