| MMS ENVIRONMENTAL STUDIES PROGRAM: ONGOING STUDIES | ||||||
| MMS OCS Region: | Alaska | |||||
| Title: | Timing and Re-interpretation of Ringed Seal Surveys (AK-93-48-39) | |||||
| Total Cost: | $412,098 | Period of Performance: | FY 2001-2004 | |||
| Conducting Organization: | University of Alaska, Coastal Marine Institute, University of Alaska Southeast | |||||
| MMS Contact: | ||||||
| Description: | ||||||
| Background | ||||||
| Ringed seals are an important resource for Native people of northern and western Alaska and an important component of the ecology of the northern marine ecosystem. Aerial surveys have been used to monitor trends in the distribution and density of ringed seals in the Alaskan Beaufort Sea without correction for variation in the proportion of seals visible to aerial observers. With CMI support, the investigators used observations on radio-instrumented seals to show that the proportion of seals visible changed rapidly during a typical survey period as seals shifted from resting in lairs to resting in the open. Furthermore, the end of that transition was shown to be associated with measurable changes in snow conditions. In this study, the investigators will develop statistical models of the proportion of seals visible as a function of snow conditions and will use those models to reanalyze data from previous aerial surveys of ringed seals. | ||||||
| Objectives | ||||||
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| Methods | ||||||
| The study will be conducted at three sites in the vicinity of Point Barrow, Prudhoe Bay and Barter Island. At Prudhoe Bay, seal breathing holes and lairs will be located by trained dogs starting in December or January. Air temperatures inside and outside the lairs will be measured using thermistors with data loggers. Those records will be used to determine dates and durations of lair use by seals in relation to snow thickness and quality. The proportion of seals in and out of lairs and under the ice will be determined by radio tracking seals in April - early June. Aircraft will be used to monitor seals when snow gets too soft for surface travel, usually in early June. Automated meteorological stations will be used to continuously record air temperature, wind speed and direction, and snow temperature in the seal’s environment during April – early June at all 3 of the study sites. Historical data on snow and ice conditions will be used to determine whether past surveys were conducted before, during, or after the seal’s transitions from lairs to resting in the open. If data on snow temperatures over the tundra are strongly correlated with those on the ice, historical data on snow temperatures over tundra will be used to retrospectively apply correction factors to previous surveys. The reliability of Ku-band backscatter radar data for determining changes in snow structure will be tested. To this end, the Jet Propulsion Laboratory will use radar data to make a "blind" determination of snow conditions at the three study sites. This result will be compared with data from each of the study sites. | ||||||
| Importance to MMS | ||||||
| Offshore production of oil in the Beaufort Sea is planned for the Northstar and Liberty. Post-lease undersea-pipeline construction is expected to result in additional acoustic and visual disturbance of ringed seals in marine areas due to increased vessel and helicopter traffic. Such disturbance has the potential for causing some long-term abandonment of industrial areas. Providing a means to determine the true densities of seals observed in aerial monitoring will help us estimate the number of seals affected by such industrial activity. Also, estimates of absolute population size require a correction factor for the proportion of seals not visible during surveys. | ||||||
| Current Status: | ||||||
| Investigators are making preparations to begin the second field season of this study. Field work will begin at Prudhoe Bay in April, 2002. | ||||||
| Final Report Due: | September 2004 | |||||
| Publications: | ||||||
| Affiliated WWW Sites: | ||||||
| Revised date: | March 2002 | |||||
| ESPIS |
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