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SC/69A/CMP/21
Resource ID
19973
Access
Open
Document Number
SC/69A/CMP/21
Full Title
Gray Whale Abundance in Laguna San Ignacio and the Bahia Magdalana Lagoon Complex, B.C.S., Mexico in 2023
Author
Urbán R., J., Viloria-Gómora, L., Martínez A., S.,, And Swartz .
Authors Summary
Beginning in 2018, observations in Laguna San Ignacio (LSI) and the Bahía Magdalena (BM) complex were characterized by declining gray whale body condition, low calf counts, and higher mortality rates. They indicated the pending Unusual Mortality Event (UME), which continued from 2019 through 2022. Information gathered in 2023 in these gray whale wintering areas suggests that the UME may be slowing and included: fewer individual whales in "poor" body condition, the first increase in the numbers of calves observed during the previous five winters of low counts, and fewer stranded dead whales in these areas. In LSI, the number of single adult (non-calf) whales counted in vessel surveys during 2023 was 194 on 6 March, higher than in the previous five winters. Compared to previous winters from 2018-2022, counts of females with calves increased throughout the winter, with the highest count of 37 pairs observed on 19 March 2023. The highest gray whale survey count in BM was obtained on 19 February in the most southerly aggregation area of Bahía Almejas and was 295 single adult whales and three female-calf pairs. In central Bahía Magdalena, gray whale counts were greatest on 18 February, with 97 adult whales and two female-calf pairs. In the northern Canal de Santo Domingo, a high count of 14 single whales was observed on 17 March, and a high count of 12 female-calf pairs on 20 February.
Publisher
IWC
Publication Year
2023
Abstract
Beginning in 2018, observations in Laguna San Ignacio (LSI) and the Bahía Magdalena (BM) complex were characterized by declining gray whale body condition, low calf counts, and higher mortality rates. They indicated the pending Unusual Mortality Event (UME), which continued from 2019 through 2022. Information gathered in 2023 in these gray whale wintering areas suggests that the UME may be slowing and included: fewer individual whales in "poor" body condition, the first increase in the numbers of calves observed during the previous five winters of low counts, and fewer stranded dead whales in these areas. In LSI, the number of single adult (non-calf) whales counted in vessel surveys during 2023 was 194 on 6 March, higher than in the previous five winters. Compared to previous winters from 2018-2022, counts of females with calves increased throughout the winter, with the highest count of 37 pairs observed on 19 March 2023. The highest gray whale survey count in BM was obtained on 19 February in the most southerly aggregation area of Bahía Almejas and was 295 single adult whales and three female-calf pairs. In central Bahía Magdalena, gray whale counts were greatest on 18 February, with 97 adult whales and two female-calf pairs. In the northern Canal de Santo Domingo, a high count of 14 single whales was observed on 17 March, and a high count of 12 female-calf pairs on 20 February.