Reproductive aspects of seven threatened shark species
30. January 2021
Reproductive aspects of seven threatened shark species captured by artisanal fisheries in the southern Caribbean Sea
A. Tagliafico, M.S. Rangel, N.R. Ehemann, N.E. Rago, M.K. Broadhurst
ABSTRACT:
Venezuela is among the top four Latin American countries with the greatest elasmobranch biodiversity. The country is also characterised by extensive artisanal fisheries, but there is a paucity of regional life-history data for many important species. Here, we provide reproductive information for one local (Carcharhinus acronotus) and six cosmopolitan species (C. brevipinna, C. falciformis, C. limbatus, Galeocerdo cuvier, Sphyrna lewini and Isurus oxyrinchus) landed by artisanal fisheries at Margarita Island, Venezuela. For two years (2006–2007), three ports and two fish markets were weekly sampled for the total length (TL), sex, and maturity stages for specimens of the assessed species. A total of 664 specimens were analysed, of which 96% were immature. We found no significant differences in the sex ratios of all species, except for C. falciformis (1.5F:1M). Based on the numbers of neonates with unhealed umbilical scars, parturition appeared to peak in the first half of the year for C. acronotus (April–June) and S. lewini (May–June). Conversely, the second half of the year appeared important for parturition in C. brevipinna (August–September), C. limbatus (July–September) and G. cuvier (September–November). Both C. falciformis and I. oxyrinchus (individuals <1.5 m TL) showed non-seasonal parturition. The large percentages of small sizes of individuals in landings imply the waters surrounding Margarita Island might represent an important nursery area, and it is likely that historical and ongoing harvest rates represent a threat for regional populations of various elasmobranchs.
Regional Studies in Marine Science, Volume 42, February 2021, DOI: 10.1016/j.rsma.2021.101646