| Summary: | Maintenance and Update Frequency: notPlanned Statement: Statement: Standard length:The standard length of larvae was measured from the tip of the snout to hypural crease or tip of notochord in preflexion larvae, under a stereo dissecting microscope with an ocular micrometer. Measurements were made to the nearest micrometer unit (0.135 mm at 10 x magnification).Otolith measurements:Otolith radius was measured from the center of the primordium to the outside edge of the otolith, through the longest axis. Three counts were made of each sagitta, and the mean increment count from a pair of sagittae was used in the analysis. Otoliths were rejected if incremental counts within or between pairs of sagittae differed by more than two.Ontogenetic development:Larval descriptions followed the general terminology used in:Fahay MP (1983) Guide to the early stages of marine fishes occurring in the western North Atlantic Ocean, Cape Hatteras to the Scotian Shelf. J. Northwest Atl. Fish. Sci. 4: 423 p.Date of initial increment formation was used in this study as reared larvae were not available to determine the relationship between the time of initial increment formation and spawning date. Given high water temperatures and fast development rates, the two are unlikely to differ by more than 2 d. The five cohorts determined thus had birth dates separated by 2 wk.Measurements of increment widths were used to estimate individual growth histories. Given a logarithmic relationship between otolith radius and standard length:SL = a·logeOR + bwhere SL = standard length of a larva at time of capture, OR = radius of sagittae and a and b are constants estimated by linear regression of logeOR on SL. The length SL, of a larva at an intermediate age i was back-calculated using the equationSLi = 5.61·logeORi - 10.56and the mean daily growth rate gi in a 3-d age interval ending at age i from the formulagi = (SLi - SLi-3)/3Individual growth rates were averaged over 3-d intervals, beginning at day 3 and ending at day 30. Ages at which analysis ...
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