Vertical distribution of eggs and larvae of Maurolicus japonicus (Sternoptychidae, Pisces) in Tosa Bay, Japan

Liezel C. Paraboles, Donna M. Guarte, Izumi Kinoshita
2019 Plankton and Benthos Research  
The vertical distribution of eggs and larvae of Maurolicus japonicus were described based on discrete depth oblique tows of a larva net seasonally collected during both day-and nighttimes at a 130 m-depth station near the continental shelf of Tosa Bay. The abundance and diel differences in the vertical distribution of eggs and larvae in relation to physical properties of the water column were also examined. Both eggs and larvae occurred only in spring and neither occurred in other seasons. In
more » ... ring, water temperature, salinity and specific gravity were less stratified in the water column with a modest upwelling to ca. 100 m-depth, around which the seasonal temperature hardly changed. Unlike the Japan Sea, with a year-round reproduction of M. japonicus, the limited occurrence of eggs and larvae in Tosa Bay was likely related to upwelling in April. Eggs were twice as abundant at night-than daytime, suggesting that this species spawns at night. Most of the eggs were in A and B-stages and aggregated at 30-70 m depth during both the day and night. Larvae that were mainly in preflexion without yolk and flexion stages, were found in the 110-70 m and 130-90 m depth layers during day-and nighttimes, respectively. Earlier larval stages were dispersed abundantly from 130-m to the surface during daytime, with little correspondence to light attenuation or chlorophyll-a concentrations. Compared to the Japan Sea, Tosa Bay yielded various mesopelagic fish species that inhabit and breed in the mesopelagic zone, so that the reproductive niche would be temporally and spatially limited for M. japonicus.
doi:10.3800/pbr.14.80 fatcat:3pubtjpgkjabph2myke3bbtwzi