The Nursery Area of the Devil Ray (Mobula munkiana) at a marine protected area in the Espíritu Santo Archipelago, Gulf of California, Mexico

04 Oct The Nursery Area of the Devil Ray (Mobula munkiana) at a marine protected area in the Espíritu Santo Archipelago, Gulf of California, Mexico

Palacios M.D

Master’s Thesis

Link: https://pdfs.semanticscholar.org/28f8/c50573753d2097769a30d9a62d32584c4172.pdf

Abstract

Nursery areas are crucial for elasmobranch populations, where females give birth and, neonates and juveniles spend their first months or years. An ecotourism industry based on the observation of small individuals of Munk’s devil ray (Mobula munkiana) was established in 2013 in a shallow bay at the Espiritu Santo Archipelago (ESA), Baja California Sur, Mexico. We assess the potential use of this bay as a nursery area of the filter feeder elasmobranch M. munkiana. We examine spatial use of the bay during one year in relation to seasonal environmental patterns using a combination of nonlethal methodologies such as traditional tagging (n=95), passive acoustic telemetry (n=7) and stable isotopes analysis (n=69). Neonates and juveniles comprised 86% of the 95 individuals captured during the study period. The residency index (RI) for tagged neonates and juveniles was significantly higher inside the bay than adjacent offshore habitats (W26= 182, p=0.0001) with a maximum of 145 consecutive days of residence within the bay. Residency index values were greater during August, September and December; corresponding to the seasonal peak in water temperature and zooplankton biovolumen. The observation of near-term pregnant females, mating behavior, females with distended cloacas and neonates evidenced that the pupping period for this species in this region extands from April to June. Review of archival photographs and videos obtained from recreational divers and ecotourism agencies operating in the area confirm that the patterns observed during the study period (2017-2018) reflected similar use of the ESA by neonates and juveniles over several years. We emphasize the ecological importance of shallow bays of the ESA for the early life stages of M. munkiana and we hypothesize that other nearshore regions in the Gulf of California likely serve as mating, pupping and nursery areas. Therefore, we highlight the need for special consideration for protection of these areas from anthropogenic activities (development, fishing, disturbance).

Citation

Palacios M.D. The Nursery Area of the Devil Ray (Mobula munkiana) at a marine protected area in the Espíritu Santo Archipelago, Gulf of California, Mexico. Master’s Thesis. CICIMAR, La Paz, Mexico, 2019.