Vertical distribution and migration of fish larvae in a Northeast Pacific bay

Abstract

Fish larvae were collected at 6 depths in Auke Bay, southeastern Alaska, USA, on 4 days in May and June 1987. On 3 dates samples were collected between 08:OO and 13:00 h, on the other date samples were collected every 4 h during 24 h. Vertical distributions of light, temperature, salinity, chlorophyll and copepod nauplii were also measured. Wind speed data were available from a nearby station. Smelt (Osmeridae) larvae, the most abundant larval fish taxon, migrated to the surface at midnight, whereas walleye pollock, flathead sole, rock sole, poacher (Agonidae) and northern smoothtongue moved deeper at dusk. During the day, most fish larvae were concentrated from 5 to 15 m, broadly overlapping the highest abundances of copepod nauplii, although poacher and northern smoothtongue were consistently deeper (15 to 25 m ) . Diurnally, smelt larvae were shallow (5 to 10 m ) , and pycnocllne depth accounted for more variabhty in their mean depth than any other biotic or physical vanable. Mean depths of the other 5 most abundant taxa were in the same rank order by depth in all 4 sets of daytime samples, and depth of isotherms below the pycnocline accounted for more vanation in their mean depths than did any other variable. The diurnal depth distributions we observed apparently result from temperature preferences among marine larval fishes, with descent at dusk as the most common form of diel vertical migration

Diurnal and tidal vertical migration of pre-settlement King George whiting Sillaginodes punctata in relation to feeding and vertical distribution of prey in a temperate bay

“…In some studies, vertlcal migratory behaviour has been linked to the vertical distribution of prey (Fortier & Leggett 1983, Munk et al 1989, Neilson & Perry 1990, Haldorson et al 1993; however, in a number of species, including S. punctafa in this study, no relationship could be found between diurnal ascenl/nocturnal diffusion and prey distribution (Yamashita et al 1985, Brewer & Kleppel 1986, Lyczkowski-Shultz & Steen 1991. Because fish larvae are visual feeders (Blaxter 1986), the migratory behaviour observed in many species might simply be a response to finding optimum light levels for detection of prey.…”

“…Steen 1991), specifically, stratification near the surface during the day, and random distribution or 'nocturnal diffusion' at night (Brewer & Kleppel 1986, Davis et al 1990, Leis 1991, Haldorson et al 1993). All larvae collected in Port Phillip Bay were relatively large (15 to 20 mm) and competent to settle (Jenkins & May 1994).…”

“…Fish larvae also show a range of vertical migratory behaviour (Neilson & Perry 1990), from nocturnal ascent (Smith et al 1978, Kendall & Naplin 1981, Boehlert et al 1985 to nocturnal descent (Boehlert et al 1985, Yamashita et al 1985, Sogard et al 1987, Davis et al 1990, Heath et al 1991, Lyczkowski-Shultz & Steen 1991. In fish larvae, die1 differences often tend to result from distinct depth preference during the day in comparison with random distribution at night or 'nocturnal diffusion' (Brewer & Kleppel 1986, Davis et al 1990, Leis 1991, Haldorson et al 1993.…”

Light sensitivity in larval fishes: Implications for vertical zonation in the pelagic zone

“…There are marked ontogenetic and taxonomic differences in the vertical distribution patterns of most larval fish taxa (Cowen et al 1993;Haldorson et al 1993;Olivar and Sabates 1997). It has been suggested that the vertical distribution of larval fishes may be a result of taxon-specific preferred light levels (Blaxter 1988;Leis 1991a).…”

“…Current velocity (Boehlert et al 1992), thermoclines (Haldorson et al 1993;Williams and Koslow 1997), and light intensity (Blaxter 1988;Leis 1991a) have all been suggested as key physical factors that structure the vertical distribution of fish larvae. The role of light intensity has been the focus of most research.…”