Logo do repositório

Percorrer por autor "Vieira, Rui P."

A mostrar 1 - 2 de 2
  • Age and growth of Brauer's lanternfish Gymnoscopelus braueri and rhombic lanternfish Krefftichthys anderssoni (Family Myctophidae) in the Scotia Sea, Southern Ocean
    Publication . Saunders, Ryan A.; Lourenço, Sílvia; Vieira, Rui P.; Collins, Martin A.; Assis, Carlos A.; Xavier, Jose C.
    This study examines age and growth of Brauer's lanternfish Gymnoscopelus braueri and rhombic lanternfish Krefftichthys anderssoni from the Scotia Sea in the Southern Ocean, through the analysis of annual growth increments deposited on sagittal otoliths. Otolith pairs from 177 G. braueri and 118 K. anderssoni were collected in different seasons from the region between 2004 and 2009. Otolith‐edge analysis suggested a seasonal change in opaque and hyaline depositions, indicative of an annual growth pattern, although variation within the populations of both species was apparent. Age estimates varied from 1 to 6 years for G. braueri (40 to 139 mm standard length; L s) and from 0 to 2 years for K. anderssoni (26 to 70 mm L s). Length‐at‐age data were broadly consistent with population cohort parameters identified in concurrent length‐frequency data from the region for both species. The estimated values of von Bertalanffy growth curves for G. braueri were L∞ = 133.22 mm, k = 0.29 year−1 and t 0 = − 0.21 year and the values for K. anderssoni were L∞ = 68.60 mm, k = 0.71 year−1 and t 0 = − 0.49 year. There were no significant (P  > 0.05) differences in growth between sexes for either species, suggesting that males and females have similar growth and development trajectories in the Scotia Sea. A positive allometric relationship between Ls and wet mass was found for each species, as well as a significant (P  < 0.0001) linear relationship between otolith size and L s. Growth performance (Ф ′) was similar between the two species and congruent with other myctophid species across the Southern Ocean. This study provides important parameters for future Southern Ocean ecosystem studies in a resource management context.
    2020Artigo científico Acesso restrito Ver mais
  • Length–weight and otolith size to standard length relationships in 12 species of Southern Ocean Myctophidae: A tool for predator diet studies
    Publication . Saunders, Ryan; Lourenço, Sílvia; Vieira, Rui P.; Collons, Martin A.; Xavier, José C.
    Fish morphometric relationships are key tools for fisheries science and studies of food web dynamics and predator foraging behaviour, but parameterisations are limited for Southern Ocean myctophids (Family Myctophidae). New standard length (LS) to total mass (MT) relationships are therefore described for the 12 biomass-dominant myctophid fish species living in the Scotia Sea, Southern Ocean, using the most comprehensive data collected in the region to date. New linear regressions for otolith size (length; OL and width; OW) and LS are also described. Significant (p < .01) LS–MT relationships were established for all species using simple non-linear regression. Significant (p < .01) relationships between LS and both OL and OW were also determined for all species, with OW being the best predictor of LS in all but one species. Our study provides a comprehensive tool for reconstructing the myctophid component of marine predator diets that will improve future food web, predator behaviour and ecosystem studies in the Scotia Sea.
    2020Artigo científico Acesso aberto Ver mais