Diet of the European Shag Gulosus aristotelis during the non-breeding season at a roost within a tidal channel

Figures & data

Table 1. Frequency of occurrence of prey species in diet samples (pellet N = 1, faecal N = 40) from European Shags roosting at Bluemull Sound, 2019–2020.

Species/family/taxon	%	N
Mollusca	4.9	2
Edible Crab Cancer pagurus	49.0	20
Velvet Swimming Crab Necora puber	76.0	31
Risso’s Crab Xantho pilipes	17.0	7
Unidentified lobster	34.0	14
Common Sea Urchin Echinus esculentus	27.0	11
Atlantic Cod Gadus morhua	2.4	1
Haddock Melanogrammus aeglefinus	2.4	1
Saithe Pollachius virens	2.4	1
Norway Pout Trisopterus esmarkii	2.4	1
Unidentified gadidae	2.4	1
Unidentified fish	34.0	14
Total number of samples		41

Table 2. Details on otoliths collected, including length, mass, fish length, and weight calculated from equations in Härkönen (1986), and estimated age class as per Hillersøy & Lorentsen (2012).

Species	Otolith length (mm)	Otolith mass (g)	Fish length (mm)	Fish weight (g)	Estimated age class
Atlantic Cod	8.8	0.039	223.6	105.9	2
Haddock	10.7	0.079	231.4	108.6	2
Saithe	5.8	0.024	132.1	19.9	1
Saithe	4.8	0.015	98.9	8.5	0
Saithe	4.7	0.013	95.8	7.72	0
Norway Pout	4.2	0.003	81.4	2.48	0
Unidentified gadidae	2.2	0.001	–	–
Mean ± sd	5.9 ± 2.9	0.025 ± 0.03	143.9 ± 66.9	42.2 ± 50.7

Härkönen, T. 1986. Guide to the Otoliths of the Bony Fishes of the Northeast Atlantic. Danbiu ApS., Hellerup, Denmark.

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Hillersøy, G. & Lorentsen, S.H. 2012. Annual variation in the diet of breeding European Shag (Phalacrocorax aristotelis) in Central Norway. Waterbirds 35: 420–429.

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