Merluccius bilinearis (Mitchill, 1814)

3.3.1 | M. bilinearis View in CoL

Stomach contents of M. bilinearis consisted mostly of conspecifics (i.e., M. bilinearis cannibalism), clupeiforms ( C. harengus and unclassified clupeids), pandalid shrimp, and euphausiids (Figure 3; Table S3). Variation in M. bilinearis diet composition was explained by season (DF = 1, 137; F = 5.73; p <0.001), depth (DF = 1, 137; F = 2.34; p = 0.003), year (DF = 1, 137; F = 1.85; p = 0.013), and longitude (DF = 1, 137; F = 1.76; p = 0.023), representing the order of explanatory variables in the final CCA model (DF = 4, 137; F = 2.92; p <0.001). The final model explained 7.9% of variation in diet composition, with the first and second CCA axes representing 4.2% and 1.9%, respectively (Figure 5a). M. bilinearis consumed relatively more (tow-level proportional mass) conspecifics and euphausiids in the spring, whereas they consumed more clupeids, crangonids, pandalids, P. triacanthus , and unclassified teleosts in the fall (Table S4). With increasing depth, M. bilinearis consumed relatively more euphausiids,

F I G U R E 3 Weighted mean proportional mass of prey taxa in stomach contents of Merluccius bilinearis ( n = 1364), Urophycis chuss ( n = 611), Urophycis tenuis ( n = 947), Lophius americanus

( n = 514), Squalus acanthias

( n = 150), and Gadus morhua

( n = 52) sampled in the nearshore Gulf of Maine. Certain prey categories are aggregations of other identifiable taxa and/or unclassified (uncl.) taxa within a higher-level classification. The “other” category includes other invertebrate taxa and unidentifiable animal remains. Fish prey are represented in the nine uppermost prey categories using a brown to blue gradient beginning with Alosinae and ending with the “fish (other/ uncl.)” category. Diet metrics for all prey taxa (best possible resolution identifications) are provided in Table S 3 .

hyperiid amphipods, and conspecifics and less crangonid shrimp, mysids, and pandalids (Figure S13). Consumption of crangonids, mysids, and P. triacanthus was positively correlated with bottom temperature, whereas consumption of alosines (i.e., Alosinae ), euphausiids, and conspecifics was negatively correlated with temperature (Figure S13). Correlations by longitude included an increase in crangonids and decreases in alosines, P. triacanthus , and unclassified teleosts from west to east (Figure S13). Relative consumptions of clupeids and hyperiids in M. bilinearis diets were negatively correlated with year, whereas crangonids and unclassified invertebrates were positively correlated with year (Figure S13).