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SC/69B/CMP/14
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Resource ID
22057
Access
Open
Document Number
SC/69B/CMP/14
Full Title
2024 GRAY WHALE ABUNDANCE IN LAGUNA SAN IGNACIO AND THE BAH?A MAGDALENA LAGOON COMPLEX, B.C.S., MXICO.
Author
Urb n R., J., Viloria-G¢mora, L., Mart¡nez A., S., And Swartz, S.L.
Authors Summary
Declining gray whale body condition, low calf counts, and higher mortality rates were documented in Laguna San Ignacio (LSI) and in the Bah¡a Magdalena (BM) complex beginning in the winter of 2018, and were indications of the pending gray whale Unusual Mortality Event (UME) which continued from 2019 through 2023. Observations during the 2024 winter included fewer individual whales in "poor" body condition, and fewer gray whale mortalities suggesting that the UME may be slowing. However, counts of female-calf pairs were the lowest recorded since abundance surveys in these winter aggregation and breeding areas since abundance surveys began in 2006, suggesting a major decline in the reproductive capacity of this population in recent years. In LSI the highest number of single adult (non-calf) whales counted in vessel surveys during 2024 was 201 whales on 25 February, which was higher than counts observed during the previous five winters of the UME.
Counts of females with calves continued to remain low during the UME winters. In 2024 calf counts were the lowest recorded numbering fewer than 9 calves throughout the birthing period from January through February, with the highest count of only 15 female-calf pairs observed on 14 March; this high calf count included mostly calves judged by their size and coloration to 1-2 months old and immigrating late in the winter into LSI from other areas. The highest gray whale survey count in BM was obtained on 24 February in the most southerly aggregation area of Bah¡a Almejas and was 243 single adult whales and no female-calf pairs. In central Bah¡a Magdalena gray whale counts were greatest on 23 February with 35 adult whales and no female-calf pairs. In the northern Canal de Santo Domingo, a high count of 17 single whales was observed on 19 February, and a count of only 2 female-calf pairs.
Publisher
IWC
Publication Year
2024