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 3 Demersal trawling discard composition and quantity. On-board sampling (n = 10, number of hauls) took place in the eastern Ionian Sea during May 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)	Calonectris diomedea	Larus michahellis	% consumption by scavengers
Species	Discard type	Description	Body shape type Fishbase¹, FAO²	Total	Mean ± SD	Mean ± SD	Calonectris diomedea	Larus michahellis	% consumption by scavengers
Aristeus antennatus* (1)	Crustacean	Benthic	Cylindrical²	2720	272.0 ± 860.14	20.3 ± 2.62	+	+	50
Liocarcinus depurator	Crustacean	Benthic	Dorsoventrally flattened²	400	40.0 ± 126.49	–	+	+
Parapenaeus longirostris* (5)	Crustacean	Benthic	Cylindrical²	16,820	1682.0 ± 2137.88	18.8 ± 3.94	+	+	76
Squilla mantis* (2)	Crustacean	Benthic	Cylindrical²	4920	492.0 ± 528.66	20.2 ± 5.00		+	80
Loligo vulgaris* (2)	Cephalopod	Pelagic	Cylindrical²	5580	558.0 ± 663.76	–	+	+	95
Sepia officinalis	Cephalopod	Benthopelagic	Cylindrical²	3080	308.0 ± 379.96	–	+	+
Arnoglossus laterna* (3)	Fish	Benthic	Ventrally flattened¹	8880	888.0 ± 1223.45	85.5 ± 14.49	+	+	70
Blennius ocellaris	Fish	Benthopelagic	Elongated¹	160	16.0 ± 7.91	80	+	+
**Boops boops (10)***	*Fish*	*Benthopelagic*	*Torpediform* ¹	*63,790*	*6379.0* ± *5700.25*	*137.8* ± *13.54*	+	+	88
Chlorophthalmus agassizii* (1)	Fish	Benthopelagic	Elongated¹	1520	152.0 ± 480.67	141.6 ± 13.90	+	+	80
Citharus linguatula* (2)	Fish	Benthic	Ventrally flattened¹	6280	628.0 ± 767.98	133.7 ± 17.69	+	+	80
Conger conger* (3)	Fish	Benthopelagic	Eel-like¹	19,360	1936.0 ± 2750.37	491.7 ± 91.70			0
**Diplodus annularis (10)***	*Fish*	*Benthopelagic*	*Laterally flattened* ¹	*299,960*	*29,996.0* ± *93,816.53*	*118.7* ± *13.43*	+	+	82
Echelus myrus	Fish	Benthopelagic	Eel-like¹	4000	400.0 ± 1264.91	480
Engraulis encrasicolus* (3)	Fish	Pelagic	Elongated¹	10,840	1084.0 ± 1822.94	130.4 ± 7.89	+	+	73
Eutrigla gurnardus	Fish	Benthopelagic	Elongated¹	1040	104.0 ± 226.43	–		+
Galeus melastomus	Fish	Benthopelagic	Elongated¹	3760	376.0 ± 1189.02	301.3 ± 134.55
Gobius spp.	Fish	Benthopelagic	Elongated¹	1000	100.0 ± 216.02	109.5 ± 0.71	+	+
Hoplostethus mediterraneus	Fish	Benthopelagic	Laterally flattened¹	1000	100.0 ± 316.23	133.3 ± 4.1	+	+
Hymenocephalus italicus	Fish	Benthopelagic	Ribbon-like¹	320	32.0 ± 101.19	139.3 ± 8.87	+	+
Lepidopus caudatus	Fish	Benthopelagic	Ribbon-like¹	5800	580.0 ± 1441.63	532 ± 33.42	+	+
**Lepidotrigla cavillone (10)***	*Fish*	*Benthopelagic*	*Elongated* ¹	*38,200*	*3820.5* ± *3964.43*	*105.3* ± *1.60*		+	72
Merluccius merluccius* (1)	Fish	Benthopelagic	Elongated¹	2400	240.0 ± 345.64	136.2 ± 33.77	+	+	80
Mullus barbatus	Fish	Benthopelagic	Laterally flattened¹	1500	150.0 ± 474.34	153	+	+
Ophisurus serpens	Fish	Benthopelagic	Eel-like¹	320	32.0 ± 101.19	–
**Pagellus acarne (10)***	*Fish*	*Benthopelagic*	*Laterally flattened* ¹	*45,000*	*4500.0* ± *14,230.25*	–	+	+	79
Pagellus erythrinus* (8)	Fish	Benthopelagic	Laterally flattened¹	26,600	2660 ± 4463.91	86.1 ± 13.64	+	+	80
Raja clavata	Fish	Benthopelagic	Ventrally flattened¹	7200	720.0 ± 2276.84	295
Raja miraletus	Fish	Benthopelagic	Ventrally flattened¹	960	96.0 ± 303.58	243
Sardina pilchardus* (1)	Fish	Pelagic	Laterally flattened¹	1580	158.0 ± 281.02	134.3 ± 4.93	+	+	90
Scorpaena elongata	Fish	Benthopelagic	Spheroid¹	200	20.0 ± 63.25	144		+
Scorpaena notata* (1)	Fish	Benthopelagic	Spheroid¹	1280	128.0 ± 280.19	110.5 ± 27.58		+	70
Scorpaena scrofa	Fish	Benthopelagic	Spheroid¹	240	24.0 ± 75.89	85		+
Serranus hepatus* (1)	Fish	Benthopleagic	Laterally flattened¹	11,490	1149.0 ± 1415.80	84.8 ± 8.6	+	+	80
**Spicara flexuosa (10)***	*Fish*	*Benthopelagic*	*Laterally flattened* ¹	*85,880*	*8588.0* ± *7363.67*	*127* ± *18.42*	+	+	82
Spicara smaris* (1)	Fish	Benthopelagic	Torpediform¹	2460	246.0 ± 534.00	109.5 ± 13.23	+	+	80
Synodus saurus* (6)	Fish	Benthopelagic	Elongated¹	21,300	2130.0 ± 5269.63	300	+	+	70
Torpedo marmorata	Fish	Benthopelagic	Ventrally flattened¹	8450	845.0 ± 2517.99	112
Torpedo nobiliana	Fish	Benthopelagic	Ventrally flattened¹	16,000	1600.0 ± 5059.64	–
Torpedo torpedo	Fish	Benthopelagic	Ventrally flattened¹	6000	600.0 ± 1897.37	230
Trachinus draco* (3)	Fish	Benthopelagic	Elongated¹	9400	940.0 ± 1605.24	197.5 ± 24.75		+	63
Trachinus radiatus	Fish	Benthopelagic	Elongated¹	320	32.0 ± 101.19	–		+
Trachurus mediterraneus* (5)	Fish	Pelagic	Laterally flattened¹	16,120	1612.0 ± 2440.55	76.6 ± 13.19	+	+	74
Trachurus trachurus* (10)	Fish	Pelagic	Laterally flattened¹	32,780	3278.0 ± 5377.11	84.8 ± 19.4	+	+	82
Trisopterus minutus	Fish	Benthopelagic	Laterally flattened¹	480	48.0 ± 151.79	105 ± 6.81	+	+
Uranoscopus scaber	Fish	Benthopelagic	Elongated¹	1760	176.0 ± 455.37	176		+

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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