Young Allis Shad Alosa alosa (Clupeidae) Would Not Be Euryphagous: An Assessment of Juvenile Diet and Prey Selectivity under Riverine-Type Conditions

Table 3

Mean values of Ivlev’s electivity index (E) calculated for each prey taxon in Alosa alosa individuals captured at one month old or two months old in the river R1, in 2018 and 2019.

	One month old		Two months old
	2018	2019	2018	2019
Cladocera	0.00	0.27	−0.24	−0.24
Copepoda (adults)		−0.68	0.25	−0.22
Copepoda (nauplii)	−1.00	−1.00		−1.00
Diptera (adults)	−0.96			−0.61
Diptera (larvae)		−0.37	0.72	0.31
Ostracoda		−1.00	0.34	0.04
Hydrachnidia		−1.00		−0.69
Coleoptera	−1.00
Terrestrial		−0.85	−1.00	−0.94
Exuviae	−1.00	−1.00	−1.00	−1.00
Trichoptera (larvae)			−0.94
Nematoda		−1.00
Rotifera		−1.00		−0.84
Isopoda
Amphipoda
Gastropoda

Sometimes, prey taxa were absent from the water sample, but observed in fish: these cases are marked with a symbol. Ivlev’s E indicates an exclusive preference when close to 1, a nonselective consumption when close to 0, and a total avoidance of prey when close to −1. Significant preferences are highlighted in bold, and significant avoidances are highlighted in italic.