Highly specialized development of the digestive system in piscivorous scombrid larvae

Abstract

SUMMARY: Scombrid fish generally display a unique early development characterized by large head , fast growth, and early piscivory. Development of the digestive system, which is a crucial element for feeding and growth, was examined using laboratory-reared larvae of 5 scombrid species: Japanese Spanish mackerel Scomberomorus niphonius, striped bonito Sarda orientalis, bluefin tuna Thunnus thynnus, yellowfin tuna T. albacares, and chub mackerel Scomber japonicus.Compared with common marine fish larvae, the digestive system appeared to develop precociously in all the scombrid larvae examined, but, the timing varied with the species. Differentiation of the juvenile-type digestive system corresponded to the appearance of piscivory and acceleration of growth rate.

The effects of light, darkness and intermittent feeding on the growth and survival of reared Atlantic bonito and Atlantic bluefin tuna larvae

“…A C C E P T E D M A N U S C R I P T fish species, which allows for this early piscivory behaviour (Kaji et al, 1996(Kaji et al, , 2002.…”

Size-selective mortality of laboratory-reared Atlantic bluefin tuna larvae: evidence from microstructure analysis of otoliths during the piscivorous phase

“…The transition period from endogenous feeding, when energy is available in the yolk-sac, to exogenous feeding, when the larva is typically dependent on available planktonic food resources, is considered a "critical period" (Hjort, 1914). However, in large pelagic species such as bluefin tuna, as in other Scombridae species, piscivory is also observed during the larval stage (Kaji et al, 2002;Sawada et al, 2005). This second dietary transition, from planktivory to piscivory feeding, might represent another major bottleneck in larval survival (Reglero et al, 2014a).…”

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

“…Although most fishes get killed by predators early in their life, piscivorous fish larvae are usually considered a minor cause of mortality because they are a small fraction of the total predator guild (Bailey and Houde 1989;Folkvord 1997;Houde 2008). This paradigm is likely true for most fishes, but some highly piscivorous fishes like tunas rapidly develop morphological traits (fast swimming speed, large eyes, large mouth-gap, voracious behavior, and rapid development of digestive system) that turn them into effective piscivores (Kaji et al 2002;Llopiz and Hobday 2015). Furthermore, adults are highly fecund fishes that target spawning grounds shared with other tunas, facilitating encounters among larvae (Reglero et al 2014).…”