Small fish eat smaller fish: a model of interaction strength in early life stages of two tuna species

Fish larvae are rarely a major driver of fish mortality, but tunas can
produce large batches of larvae that rapidly develop the capacity to kill
other fish. We combine a model for the killing potential from Atlantic
bluefin tuna (BFT) larvae on larval albacore (ALB) with field observations
at a major spawning ground. Both species spawn from June to August, but
BFT has a narrow spawning peak at the beginning of the season that results
in priority effects. Our model shows that, following a recent stock
recovery, BFT larvae have increased their killing pressure, leaving areas
of up to 1000km2 with <1% chance of ALB daily survival. Such
increase in killing pressure suggests larval ALB has reduced chances to
survive, yet in large areas with few BFT other drivers of early survival
prevail over BFT predation. This shows that strong predatory interactions
can occur during larval stages in some fishes.