Growth, maturity, and diet of the pearl whipray (Fontitrygon margaritella) from the Bijagós Archipelago, Guinea-Bissau

Abstract

The pearl whipray Fontitrygon margaritella (Compagno & Roberts, 1984) is a common elasmobranch in coastal western African waters. However, knowledge on their life-history and trophic ecology remains limited. Therefore, we aimed to determine the growth, maturity and diet of F. margaritella from the Bijagós Archipelago in Guinea-Bissau. Growth was modelled with: von Bertalanffy, Gompertz and logistic functions. Model selection revealed no model significantly outperformed another. The sampled age ranged from less than 1 to 7 years (1.8 ± 1.9 cm, mean ± standard deviation) and size (disc width) ranged from 12.2 to 30.6 cm (18.7 ± 5.2 cm). Size-at-maturity was estimated at 20.3 cm (95% CI [18.8–21.8 cm]) for males and 24.3 cm for females (95% CI [21.9–26.5 cm]), corresponding ages of 2.2 and 3.9 years. The diet differed significantly among young-of-the-year (YOY), juveniles and adults (p = 0.001). Diet of all life stages consisted mainly of crustaceans (27.4%, 28.5%, 33.3%) and polychaetes (12.5%, 26.7%, 20.3%), for YOY, juveniles and adults respectively. This study shows that F. margaritella is relatively fast-growing, matures early and experiences ontogenetic diet shifts. These results contribute to status assessments and conservation efforts of F. margaritella and closely related species.

Where land meets sea: Intertidal areas as key‐habitats for sharks and rays

“…small bivalves and shrimp) (Gray et al, 1997). A similar ontogenetic shift was shown for other ray and benthic shark species (Bethea et al, 2007; Clements et al, 2022; Lim et al, 2018). Hollensead et al (2016) describes that juvenile smalltooth sawfishes ( Pristis pectinate , Pristidae) most likely use the edge of intertidal flats to ambush schools of mullet (Mugilidae) leaving the intertidal habitat during receding tide.…”

Diet of the critically endangered blackchin guitarfish Glaucostegus cemiculus revealed using DNA metabarcoding

“…A recent study on the diet of a sympatric ray species in the Bijag os archipelago, the pearl whipray (Fontitrygon margaritella), found polychaetes and crustaceans to be the most important prey for this species (Clements et al, 2022). Crustaceans (e.g., A. tangeri and P. kerathurus) were also found to be the most important prey group for a large community of shorebirds in the Bijag os, suggesting that they may be highly available (Correia et al, 2023;Lourenço et al, 2017;Zwarts, 1985).…”

“…was not yet observed as important in fish diet (e.g., Longhurst, 1957;Correia et al, 2017;Clements et al, 2022). Other fiddler crab species, however, have been identified as important prey for killifishes, puffers, and gobies in different regions (Krumme et al, 2007;Rozas & LaSalle, 1990;Zulkifli et al, 2012).…”