The use of demersal trawling discards as a food source for two scavenging seabird species: a case study of an eastern Mediterranean oligotrophic marine ecosystem

Karris, Georgios; Ketsilis-Rinis, Vlasis; Kalogeropoulou, Anastasia; Xirouchakis, Stavros; Machias, Athanasios; Maina, Irida; Kavadas, Stefanos

doi:10.1186/s40657-018-0118-5

Avian Research

Table 4 Demersal trawling discard composition and quantity. On-board sampling (n = 9, number of hauls) took place in the eastern Ionian Sea during December 2014

From: The use of demersal trawling discards as a food source for two scavenging seabird species: a case study of an eastern Mediterranean oligotrophic marine ecosystem

Species of fishery discards							Seabird species	Exploitation of discards
Species	Discard type	Description	Body shape type Fishbase¹, FAO²	Biomass (g)		Length (mm)	Larus michahellis	% consumption by scavengers
Species	Discard type	Description	Body shape type Fishbase¹, FAO²	Total	Mean ± SD	Mean ± SD	Larus michahellis	% consumption by scavengers
Liocarcinus depurator	Crustacean	Benthic	Dorsoventrally flattened²	300	33.3 ± 100.00	24	+
Pagurus sp.	Crustacean	Benthic	Cylindrical²	500	55.6 ± 166.67	–
**Parapenaeus longirostris (5)***	*Crustacean*	*Benthic*	*Cylindrical* ²	*16,470*	*1830.0* ± *2536.80*	*19.8* ± *3.46*	+	74
Squilla mantis	Crustacean	Benthic	Cylindrical²	5980	664.4 ± 1296.29	22.9 ± 2.59	+
Alloteuthis media	Cephalopod	Pelagic	Cylindrical²	5655	628.3 ± 666.50	–	+
Loligo vulgaris	Cephalopod	Pelagic	Cylindrical²	600	66.7 ± 200.00	–	+
Sepia officinalis	Cephalopod	Benthopelagic	Cylindrical²	3200	355.6 ± 640.53	–	+
Sepiolidae sp.	Cephalopod	Benthopelagic	Cylindrical²	180	20.0 ± 40.00	–	+
Arnoglossus laterna	Fish	Benthic	Ventrally flattened¹	7950	883.3 ± 701.78	92 ± 16.32	+
Aspitrigla cuculus	Fish	Benthopelagic	Elongated¹	1000	111.1 ± 333.33	173	+
Blennius ocellaris	Fish	Benthopelagic	Elongated¹	910	101.1 ± 249.02	110	+
**Boops boops (10)***	*Fish*	*Benthopelagic*	*Torpediform* ¹	*87,250*	*9694.4* ± *10,071.45*	*135.6* ± *13.20*	+	78
Cepola macrophthalma	Fish	Benthopelagic	Ribbon-like¹	100	11.1 ± 33.33	148	+
Citharus linguatula	Fish	Benthic	Ventrally flattened¹	7800	866.7 ± 986.47	124.8 ± 16.88	+
**Conger conger (2)***	*Fish*	*Benthopelagic*	*Eel* - *like* ¹	*13,100*	*1456.6* ± *2206.02*	*448.9* ± *71.83*		0
Dentex maroccanus	Fish	Benthopelagic	Laterally flattened¹	6040	671.1 ± 1282.77	91.9 ± 38.30	+
Echelus myrus	Fish	Benthopelagic	Eel-like¹	220	24.4 ± 73.33	562 ± 50.91
Engraulis encrasicolus	Fish	Pelagic	Elongated¹	3450	383.3 ± 463.68	99.5 ± 16.51	+
Gobius spp.	Fish	Benthopelagic	Elongated¹	2945	327.2 ± 530.02	72.5 ± 34.47	+
Lepidotrigla cavillone	Fish	Benthopelagic	Elongated¹	6850	761.1 ± 681.81	98 ± 15.58	+
Merluccius merluccius	Fish	Benthopelagic	Elongated¹	6660	740.0 ± 903.83	145.2 ± 18.87	+
Mullus barbatus	Fish	Benthopelagic	Laterally flattened¹	2340	260.0 ± 361.11	106.7 ± 13.16	+
Ophidion barbatum	Fish	Benthopelagic	Eel-like¹	2000	222.2 ± 666.67	207.5 ± 23.33
Pagellus acarne	Fish	Benthopelagic	Laterally flattened¹	1200	133.3 ± 400.00	152	+
Pagellus erythrinus	Fish	Benthopelagic	Laterally flattened¹	1600	177.8 ± 268.22	78.8 ± 12.48	+
Sardina pilchardus	Fish	Pelagic	Laterally flattened¹	400	44.4 ± 133.33	138	+
Serranus hepatus	Fish	Benthopelagic	Laterally flattened¹	8600	955.6 ± 911.20	88.4 ± 8.53	+
**Spicara flexuosa (6)***	*Fish*	*Benthopelagic*	*Laterally flattened* ¹	*19,500*	*2166.7* ± *1593.74*	*125* ± *19.86*	+	70
Spicara smaris	Fish	Benthopelagic	Torpediform¹	1300	144.4 ± 335.82	131.3 ± 8.91	+
Synodus saurus	Fish	Benthopelagic	Elongated¹	2000	222.2 ± 666.67	249	+
Torpedo marmorata	Fish	Benthopelagic	Ventrally flattened¹	3850	427.8 ± 788.63	171.5 ± 63.62
Torpedo nobiliana	Fish	Benthopelagic	Ventrally flattened¹	2080	231.1 ± 480.32	104.7 ± 2.52	–
Trachinus draco	Fish	Benthopelagic	Elongated¹	500	55.6 ± 166.67	145	+
**Trachurus trachurus (10)***	*Fish*	*Pelagic*	*Laterally flattened* ¹	*234,900*	*26,100* ± *23,937.31*	*115.8* ± *7.76*	+	78
Trisopterus minutus	Fish	Benthopelagic	Laterally flattened¹	4200	466.7 ± 700.00	138.8 ± 8.54	+
Uranoscopus scaber	Fish	Benthopelagic	Elongated¹	400	44.4 ± 133.33	93	+
Zeus faber	Fish	Benthopelagic	Laterally flattened¹	100	11.1 ± 33.33	58	–

Seabird species scavenging on fishery discards in the Ionian Sea are also shown. (+) shows discard use per seabird species whereas () shows non consumption respectively. Species in bolditalics indicate the most abundant fishery discard items as potential food source for seabirds. Asterisk * (number of experiments) indicates experimentally discarded species for which quantification of scavenging process by seabirds was possible

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ISSN: 2053-7166

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