Browsing by Author "Rosa, D."
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- Age and growth of the blue shark (Prionace glauca) in the Indian OceanPublication . Andrade, Inês; Rosa, D.; Muñoz-Lechuga, R.; Coelho, RuiSince there is still a lack of biological information regarding Prionace glauca in the Indian Ocean, specifically in terms of age estimation and growth modelling, the age and growth of this species was studied by analysing vertebral samples. All samples were collected from specimens captured by pelagic longliners between March 2013 and September 2016, with sizes ranging from 82 to 301 cm fork length (LF). Two growth models were fitted to the age data, a three-parameter von Bertalanffy growth function (VBGF) re-parameterized to calculate L0 (size at birth) and a two-parameter VBGF with a fixed L0. The latter was considered the most adequate to describe the growth of the species, with the estimated parameters being L∞ = 283.8 cm LF, k = 0.13 year−1 for males and L∞ = 290.6 cm LF, k = 0.12 year−1 for females. These results suggest that females have a slower growth than males. The maximum age estimated was 25 years, representing the oldest attributed age to this species so far. Further work is needed regarding P. glauca in the Indian Ocean, but this study adds important life-history information that can contribute for the management and conservation of the species.
- An updated revision of shortfin mako size distributions in the AtlanticPublication . Coelho, Rui; Domingo, A.; Courtney, D.; Cortés, E.; Arocha, F.; Liu, K-M; Yokawa, K.; Yasuko, S.; Hazin, Fábio H. V.; Bowlby, H.; Abid, N.; Rosa, D.; Lino, PedroAs part of an ongoing cooperative program for fisheries and biological data collection within the ICCAT Sharks Working Group, information collected by fishery observers and scientific projects from several fishing nations in the Atlantic were analyzed. Datasets included information on geographic location, size and sex. A total of 42,979 shortfin mako records collected between 1989 and 2017 were compiled. Sizes considered ranged between 60 and 353 cm FL (fork length). Of those, sex information was available for 24,316 specimens. Considerable variability was observed in the size distribution by region and season, with larger sizes tending to occur in equatorial and tropical regions and smaller sizes in higher latitudes. Variability between coastal and more oceanic waters is also likely. Most fleets showed unimodal distributions, but in some cases there were bimodal patterns. The distributional patterns presented in this study provide an advance in the understanding of shortfin mako size distribution in the Atlantic, and can be used in the next update of the ICCAT shortfin mako stock assessment.