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Census of Gray Whale Abundance in San Ignacio Lagoon: A Follow-Up Study in Response to Low Whale Counts Recorded during an Acoustic Playback Study of Noise-Effects on Gray Whales.

PB94195062

Publication Date	1994
Personal Author	Jones, M. L.; Swartz, S. L.; Dahlheim, M. E.
Page Count	44
Abstract	Surveys done in 1984 as part of a study to determine the effects of noise on gray whales (Eschrichtius robustus) that calve and breed in San Ignacio Lagoon, Mexico sighted substantially fewer whales than had been sighted in the lagoon from 1978 through 1982. Two additional surveys, the results of which are described in the paper, were done in 1985 to determine whether a population decline had occurred and was continuing in the lagoon. A review of human activities in the lagoon from 1978 through 1985, which could have influenced the relative abundance of whales is also reported. The second series of surveys in 1985 was done in mid-March, when in previous years the maximum number of cows and calves had gathered prior to beginning the north migration. Regression analysis of the high counts in 1978, 1979, 1980, 1981, 1982, and 1985 indicate that, during this seven year period, the maximum number of whales present in San Ignacio Lagoon increased an average of 4.5% per year. The study results suggest that (1) the noise-effect studies conducted in 1984 caused both single whales and cow-calf pairs to abandon or avoid San Ignacio Lagoon; and (2) most if not all of the whales returned to and used this lagoon in 1985 as they had in 1978-82.
Keywords	Whales(Mammals) Noise exposure Mexico Noise pollution Surveys Cencus Animal migrations Populations Abundance Regression analysis Behavior Reproduction(Biology) Response Noise intensity Humans Regulations Environmental impacts Eschrichtius robustus Baja(California) Grey whales San Ignacio Lagoon Ambiant noise Cow-calf pairs
Source Agency	Marine Mammal Commission
NTIS Subject Category	47D - Biological Oceanography 68B - Noise Pollution & Control
Corporate Authors	Cetacean Research Associates, Inc., Washington, DC.; Marine Mammal Commission, Washington, DC.
Supplemental Notes	Sponsored by Marine Mammal Commission, Washington, DC.
Document Type	Technical Report
Title Note	Final rept.
NTIS Issue Number	199420
Contract Number	MMC-MM2911023-0

Census of Gray Whale Abundance in San Ignacio Lagoon: A Follow-Up Study in Response to Low Whale Counts Recorded during an Acoustic Playback Study of Noise-Effects on Gray Whales.

Census of Gray Whale Abundance in San Ignacio Lagoon: A Follow-Up Study in Response to Low Whale Counts Recorded during an Acoustic Playback Study of Noise-Effects on Gray Whales.
PB94195062

Publication Date	1994
Personal Author	Jones, M. L.; Swartz, S. L.; Dahlheim, M. E.
Page Count	44
Abstract	Surveys done in 1984 as part of a study to determine the effects of noise on gray whales (Eschrichtius robustus) that calve and breed in San Ignacio Lagoon, Mexico sighted substantially fewer whales than had been sighted in the lagoon from 1978 through 1982. Two additional surveys, the results of which are described in the paper, were done in 1985 to determine whether a population decline had occurred and was continuing in the lagoon. A review of human activities in the lagoon from 1978 through 1985, which could have influenced the relative abundance of whales is also reported. The second series of surveys in 1985 was done in mid-March, when in previous years the maximum number of cows and calves had gathered prior to beginning the north migration. Regression analysis of the high counts in 1978, 1979, 1980, 1981, 1982, and 1985 indicate that, during this seven year period, the maximum number of whales present in San Ignacio Lagoon increased an average of 4.5% per year. The study results suggest that (1) the noise-effect studies conducted in 1984 caused both single whales and cow-calf pairs to abandon or avoid San Ignacio Lagoon; and (2) most if not all of the whales returned to and used this lagoon in 1985 as they had in 1978-82.
Keywords	Whales(Mammals) Noise exposure Mexico Noise pollution Surveys Cencus Animal migrations Populations Abundance Regression analysis Behavior Reproduction(Biology) Response Noise intensity Humans Regulations Environmental impacts Eschrichtius robustus Baja(California) Grey whales San Ignacio Lagoon Ambiant noise Cow-calf pairs
Source Agency	Marine Mammal Commission
NTIS Subject Category	47D - Biological Oceanography 68B - Noise Pollution & Control
Corporate Authors	Cetacean Research Associates, Inc., Washington, DC.; Marine Mammal Commission, Washington, DC.
Supplemental Notes	Sponsored by Marine Mammal Commission, Washington, DC.
Document Type	Technical Report
Title Note	Final rept.
NTIS Issue Number	199420
Contract Number	MMC-MM2911023-0