Marine traffic and whales in Mexico: A collision that is preventable
The expansion of maritime traffic driven by port development and global trade has increased the risk of vessel–whale collisions, an important source of whale mortality worldwide and an emerging concern in Mexico. Key ports such as Manzanillo and Lázaro Cárdenas continue to grow, intensifying ship traffic along migratory routes of gray, humpback, and blue whales, as well as within the habitats of resident species in the Gulf of California. Although international databases report few incidents, national studies and photo-identification records indicate that collisions are more frequent than documented, highlighting the need for improved monitoring and reporting systems.
Mexico is well positioned to address this challenge through existing legal, institutional, and scientific capacities. Current environmental and maritime frameworks provide a basis for implementing measures such as traffic separation schemes, speed management, and whale alert systems. Evidence from international experiences demonstrates that such interventions can effectively reduce collision risks without hindering maritime activity. By integrating scientific data into nautical charts and navigational advisories, Mexico can advance practical and low-cost solutions that enhance marine safety, protect whale populations, and support sustainable coastal economies.
Author: Eduardo Nájera-Hillman
Patterns of species richness and detection of mammals in the Sierra la Laguna Biosphere Reserve
This study analyzes trends in mammal species richness and detection in the Sierra la Laguna Biosphere Reserve, Baja California Sur, Mexico. Using camera traps at various altitudes, vegetation types, and distances from human settlements, we documented twelve species, including both native and introduced mammals. We confirmed the prevalence of ungulates, carnivores, and other native species; however, despite local reports of cougar presence, the cameras failed to capture evidence of this species. Results showed a significant negative correlation between species richness and elevation, while proximity to ranches, season, and vegetation type did not appear to impact species richness or detection. Additionally, the persistent presence of introduced ungulate species raises concerns about their effects on plant communities. Our findings contribute to understanding mammal community dynamics and provide valuable, updated information for managing introduced species and conserving medium- and large-sized mammals in this protected area.
Authors:
- Eduardo Nájera-Hillman
- Osiel Alejandro Flores Rosas
- Juan Villalpando Pérez
- Lázaro Israel Rangel Castañeda
Mercury concentrations in Baja California Sur fish: Dietary exposure assessment
Total mercury concentrations ([THg]) in muscle were determined in commercial finfish and elasmobranchs from Baja California Sur (BCS), Mexico to evaluate dietary Hg exposure for BCS communities, including the relationship of trophic ecology, length and mass with [THg] that might drive future consumption advice (e.g., recommend limited consumption of large fish for some species). The [THg] ranged from 0.06 to 528.02 mg kg1 ww in finfish and 17.68e848.26 mg kg1 ww in elasmobranchs. Relative to the consumption threshold set for predatory fish in Mexico, all species had a concentration below 1000 mg kg1 ww. As expected, 16 (4.02%) and 75 (18.84%) individual fish were above advisory thresholds of 500 and 200 mg kg1 ww, respectively. The hazard quotients (HQs) in most species were significantly <1.0, only banded guitarfish showed a significant median HQ > 1.0. Thus, the relative level of risk of high Hg exposure is low for most species.
Authors:
- Daniela A. Murillo-Cisneros — Centro de Investigaciones Biologicas Del Noroeste, S.C. Planeacion Ambiental y Conservacion. Instituto Politecnico Nacional 195, Playa Palo de Santa Rita Sur, La Paz, Baja California Sur, C.P. 23096, Mexico
- Tania Zenteno-Savín — Centro de Investigaciones Biologicas Del Noroeste, S.C. Planeacion Ambiental y Conservacion.
- John Harley — Alaska Coastal Rainforest Center, University of Alaska Southeast, 11175 Auke Lake Way, Juneau, AK, 99801, USA
- Andrew Cyr — Biomedical Learning and Student Training, University of Alaska Fairbanks, 2141 Koyukuk Dr., Fairbanks, AK, 99775, USA
- Pablo Hernandez-Almaraz — Centro de Investigaciones Biologicas Del Noroeste, S.C. Planeacion Ambiental y Conservacion.
- Ramon Gaxiola-Robles — Centro de Investigaciones Biologicas Del Noroeste, S.C. Planeacion Ambiental y Conservacion and Hospital General de Zona No.1. Instituto Mexicano Del Seguro Social. 5 de Febrero y Heroes de La Independencia, Centro, La Paz, Baja California Sur, C.P. 23000, Mexico
- Felipe Galvan-Magaña — Instituto Politecnico Nacional, Centro Interdisciplinario de Ciencias Marinas, Av. I.P.N. S/n, Colonia Playa Palo de Santa Rita, Apartado Postal 592, La Paz, Baja California Sur, C.P. 23000, Mexico
- Todd M. O’Hara — Bilingual Laboratory of Toxicology, Veterinary Integrative Biosciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX, 77843, USA