MMS Publishes Sperm Whale Seismic Study
The U.S. Minerals Management Service has published a report on sperm whales, an endangered species living in the northern Gulf of Mexico. The report contains the results of the six-year,
$ 9.3 million Sperm Whale Seismic Study (SWSS), which focuses on the effects of oil and gas seismic exploration on sperm whales in the Gulf.
The report's principal conclusions follow:
SWSS results support conservation of sperm whales in the northern Gulf of Mexico as a
Sperm whales are present year-round in the Gulf, with females generally having significant site fidelity and males and females exhibiting significant differences in habitat usage.
The sperm whale population off the Mississippi River Delta likely has a core size of about 140 individuals.
Some groups of sperm whales in the Gulf were mixed-sex groups of females/immatures and others were groups of bachelor males. Typical group size for mixed groups was 10 individuals, which is smaller than group sizes in some other oceans.
The typical diving and underwater behaviors of the Gulf's sperm whales are similar to those of animals in other oceans.
The typical feeding and foraging behaviors of the Gulf's sperm whales are similar to those of animals in other oceans, although differences in defecation rates suggest possible differences in feeding success.
In the otherwise oligotrophic Gulf of Mexico, the eddy field contributes to development of regions of locally high surface productivity that in turn may create conditions favorable for
trophic cascade of surface production to the depths where Gulf sperm whales dive to forage.
There appeared to be no horizontal avoidance to controlled exposure of seismic airgun sounds by sperm whales in the main SWSS study area.
Data analysis suggests it is more likely than not that some decrease in foraging effort may occur during exposure to full-array airgun firing as compared to the post-exposure condition, at least for some individuals.
Knowledge of the acoustic propagation and airgun sound characteristics is critical to
developing the capability for accurate predictions of exposures and the modeling of potential
The report makes the following recommendations:
"1. Continue to conserve Gulf of Mexico sperm whales as a unique stock.
Click here to read report
2. Implement an ongoing monitoring program to continue and extend SWSS understanding of biology and behavior of Gulf whales, focused on providing information required for sperm whale population conservation.
3. Extend controlled exposure experiment work.
4. Incorporate information on the prey field of sperm whales in the Gulf of Mexico,
including identification of prey species and their vertical distribution, as an integral
design element of future controlled exposure experimentation.
5. Continue development of sensor and instrument capabilities, including enhancements to the D-tag and addition of new sensor capability for the S-tag.
6. Continue development of passive acoustic monitoring (PAM) techniques, so that PAM as well as visual observers are design elements in future seismic surveys."
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