2017 RESEARCH REPORT FOR LAGUNA SAN IGNACIO & BAHIA MAGDALENA
The 2017 winter at Laguna San Ignacio and Bahía Magdalena was unusually cold, rainy, and windy, conditions that significantly reduced the number of work days on the water. Despite the weather, LSIESP researchers were able to complete the annual surveys for gray whale (Eschrichtius robustus) abundance, photo-graphic identification of individual whales in both locations. Dedicated photographic-identification surveys of bottlenose dolphin (Tursiops truncatus) continued for a second winter in Laguna San Ignacio to determine the number of dolphin resident in the lagoon, and to identify those that are transient to this region. The Bahía Magdalena team surveyed gray whales in the southern aggregation areas of Lopez Mateos, Bahía Magdalena, and Bahía Almejas.
The information database developed during the past 12 winters by the Laguna San Ignacio Ecosystem Science Program (LSIESP) for Laguna San Ignacio and Bahía Magdalena is sufficient to detect, describe, and understand trends in the use of winter aggregation areas by gray whales during their winter breeding season. The 2017 winter is a good example, when the average water temperature was 2-3 degrees C° cooler than in 2016, known as the “La Niña” condition. The 2017 counts of gray whales in both areas were consistent with previous winters with cooler sea surface temperature with fewer whales utilizing the northern aggregation areas and more whale migrating further south to utilize the more southerly aggregations areas. Some whales entered the Gulf of California as far north as Bahía de La Paz, and three gray whales were reported to have crossed the Gulf of California to visit the mainland coast at Mazatlan. Such long-term databases are powerful tools for the interpretation of gray whale migrations, movements within and occupation of winter breeding and aggregation areas.
