Motta, F. d. S. | bioRxiv Science

bioRxiv2020

First study on age and growth of the deep-water Goblin Shark, Mitsukurina owstoni (Jordan, 1898)

Due to poorly mineralizing structures, ageing deep-water elasmobranchs requires nonconventional techniques. The aim of the present study was to develop a reliable ageing technique using the vertebral centrum to provide information about the age and growth parameters in the Goblin Shark, Mitsukurina owstoni (Jordan, 1898). One vertebral centrum from an individual measuring 315.2 cm in total length was analysed. A minimum age of 27 years was estimated. By incorporating priors based on the growth of deep-water sharks and an additional likelihood on L{infty} using data on large male Goblin Sharks, a Bayesian von Bertalanffy growth model was estimated with a male L{infty} of 364 cm total length, weigh 215 kg at L{infty}, grow slowly with a k equal to 0.049, mature at 16.5 years, and live up to 55 years. Our results are essential to provide useful life history information, with the aim of elucidating the cryptic ecology and biology of this deep-water shark.

zoology↗

bioRxiv2018

Network of small no-take marine reserves reveal greater abundance and body size of fisheries target species

No-take marine reserves (NTRs), i.e. areas with total fishing restrictions, have been established worldwide aiming to provide biodiversity and ecosystem conservation. Brazil has established NTRs, but currently lacks scientific knowledge and understanding of their ecological role, particularly regarding rocky reefs in subtropical regions. Consequently, this study aimed to contrast NTR, from the 30 year old Tupinambas Ecological Station, and comparable fished sites across a coastal biogeographic gradient to investigate the effect of fishing and habitat variability on the abundance and body-size of rocky reef fish. We used Baited Remote Underwater stereo-Video (stereo-BRUVs) and Diver Operated stereo-Video (stereo-DOVs) systems to simultaneously sample reef fish and habitat. Model selection and results identified habitat and biogeographic variables, such as distance from shore, as important predictor variables, explaining several aspects of the fish assemblage. The effect of protection was important in determining the abundance and body-size of targeted species, in particular for epinephelids and carangids. Conversely, species richness was correlated with habitat complexity and not with protection status. This is the first study to publish data using these novel survey methods in the Southeastern Atlantic and demonstrate their utility, in combination with an established network of NTRs, to provide benchmarks for conservation and fisheries management.

ecology↗