Table 1. Prey items of subadult and adult grey seal males indicated by gut morphological i.e. hard part (HP, mass %) and DNA (sequence %) prey proportions, and the frequencies of occurrence (Freq %).
| Prey items | Subadult males | Adult males | ||||||
|---|---|---|---|---|---|---|---|---|
| HP (%) n = 37 |
DNA (%) n = 42 |
HP (%) n = 51 |
DNA (%) n = 44 |
|||||
| Prop | Freq | Prop | Freq | Prop | Freq | Prop | Freq | |
| Baltic herring Clupea harengus | 46.7 | 59.5 | 39.8 | 69.0 | 29.0 | 58.8 | 24.6 | 63.6 |
| Perch Perca fluviatilis | 13.6 | 21.6 | 11.0 | 21.4 | 13.0 | 35.3 | 11.1 | 36.4 |
| Eelpout Zoarces viviparus | 10.3 | 13.5 | 6.1 | 28.6 | 7.0 | 17.6 | 8.5 | 18.2 |
| Bream Abramis brama | ND | ND | 6.0 | 16.7 | 3.4 | 5.9 | 10.8 | 22.7 |
| Roach Rutilus rutilus | 3.0 | 8.1 | 3.4 | 11.9 | 5.0 | 13.7 | 5.1 | 31.8 |
| Sprat Sprattus sprattus | 2.6 | 13.5 | 9.2 | 23.8 | 0.5 | 7.8 | 2.9 | 22.7 |
| Pikeperch Sander lucioperca | 4.3 | 5.4 | 2.4 | 16.7 | 1.5 | 7.8 | 5.8 | 13.6 |
| Common whitefish C. lavaretus | 0.3 | 2.7 | ND | ND | 9.2 | 21.6 | ND | ND |
| Atlantic salmon Salmo salar | ND | ND | 0.6 | 9.5 | 1.5 | 3.9 | 6.2 | 6.8 |
| European eel Anguilla anguilla | 3.0 | 5.4 | 1.7 | 7.1 | 1.6 | 3.9 | 1.0 | 6.8 |
| Three-spined stickleback G. aculeatus | < 0.1 | 2.7 | 5.3 | 7.1 | ND | ND | <0.1 | 2.3 |
| Cod Gadus morhua | 0.2 | 2.7 | 3.3 | 11.9 | 1.1 | 5.9 | 0.3 | 2.3 |
| Burbot Lota lota | ND | ND | 3.4 | 9.5 | 0.5 | 2.0 | 0.5 | 4.5 |
| Pike Esox lucius | ND | ND | ND | ND | 1.8 | 2.0 | 2.2 | 6.8 |
| Isopod crustacean Saduria entomon | 2.9 | 8.1 | ND | ND | <0.1 | 3.9 | ND | ND |
| Sea trout Salmo trutta | 0.9 | 2.7 | ND | ND | <0.1 | 2.0 | 1.2 | 2.3 |
| Ruffe Gymnocephalus cernua | 1.0 | 5.4 | 0.3 | 4.8 | <0.1 | 2.0 | 0.8 | 2.3 |
| European flounder Platichthys flesus | ND | ND | ND | ND | 1.7 | 5.9 | ND | ND |
| Turbot Scophthalmus maximus | ND | ND | ND | ND | 1.4 | 2.0 | ND | ND |
| Four-horned sculpin M. quadricornis | 0.4 | 2.7 | ND | ND | 0.9 | 5.9 | ND | ND |
| Smelt Osmerus eperlanus | 0.5 | 8.1 | < 0.1 | 2.4 | 0.3 | 5.9 | 0.2 | 6.8 |
| Sand goby Pomatoschistus minutus | ND | ND | 0.7 | 2.4 | ND | ND | < 0.1 | 4.5 |
| Common dab Limanda limanda | ND | ND | ND | ND | 0.7 | 2.0 | ND | ND |
| White bream Blicca bjoerkna | ND | ND | < 0.1 | 4.8 | ND | ND | 0.2 | 4.5 |
| Tench Tinca tinca | ND | ND | ND | ND | 0.1 | 2.0 | ND | ND |
| Black goby Gobius niger | ND | ND | < 0.1 | 2.4 | <0.1 | 2.0 | ND | ND |
| Rainbow trout Oncorhynchus mykiss | ND | ND | < 0.1 | 2.4 | ND | ND | ND | ND |
| Cyprinids Cyprinidae | 5.0 | 16.2 | ND | ND | 14.4 | 31.4 | ND | ND |
| Whitefishes Coregonus spp | ND | ND | 2.2 | 11.9 | 0.3 | 3.9 | 13.2 | 27.3 |
| Percids Percidae | 2.2 | 5.4 | ND | ND | 3.1 | 11.8 | ND | ND |
| Sculpins Cottidae | < 0.1 | 2.7 | 2.4 | 4.8 | <0.1 | 3.9 | 1.8 | 13.6 |
| European flounder or plaice Plat. flesus or Pleur. platessa |
ND | ND | < 0.1 | 2.4 | ND | ND | 2.4 | 4.5 |
| Clupeids Clupeidae | 0.3 | 2.7 | ND | ND | 2.0 | 5.9 | ND | ND |
| Daces Leuciscus sp. | ND | ND | 1.2 | 2.4 | ND | ND | 1.0 | 2.3 |
| Sand lances Ammodytidae | 1.1 | 8.1 | 0.7 | 4.8 | ND | ND | ND | ND |
| Lampreys Petromyzontidae | 1.7 | 2.7 | ND | ND | ND | ND | ND | ND |
| Gobies Gobiidae | < 0.1 | 5.4 | ND | ND | <0.1 | 15.7 | ND | ND |
The items identified at species levels were listed first (in the order of decreasing average proportion in the subadult and adult diets, indicated by the HP and DNA analyses) and those identified at species group levels were listed after the species. The number of subadult and adult males from which both HP and DNA were recorded was 33 and 40, respectively.