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Factors Affecting Haul-Out Behavior of Harbor Seals (Phoca vitulina) in Tidewater Glacier Inlets in Alaska: Can Tourism Vessels and Seals Coexist?

Blundell GM, Pendleton GW - PLoS ONE (2015)

Bottom Line: Cruise ships had the strongest negative effect; however, most vessel types negatively affected haul-out probability.End of haulouts was associated with increasing cloud cover, low ice availability, and vessel presence; large-sized tourism vessels or all-vessel-types combined were significant predictors of ending a haul-out bout.Potential disturbances of harbor seals could be reduced, enabling longer resting times for seals and fewer interruptions for nursing pups, if vessels focused the majority of visits to glacial habitat to before or after the hours of 08:00-17:00 or, less optimally, 09:00-16:00.

View Article: PubMed Central - PubMed

Affiliation: Alaska Department of Fish and Game, Division of Wildlife Conservation, Juneau, Alaska, United States of America.

ABSTRACT
Large numbers of harbor seals (Phoca vitulina) use habitat in tidewater glaciers in Alaska for pupping, breeding, and molting. Glacial fjords are also popular tourist destinations; however, visitation by numerous vessels can result in disturbance of seals during critical life-history phases. We explored factors affecting haul-out behavior of harbor seals at a glacial site frequented by tourism vessels. In 2008-10, we deployed VHF transmitters on 107 seals in Endicott Arm, Alaska. We remotely monitored presence and haul-out behavior of tagged seals and documented vessel presence with time-lapse cameras. We evaluated the influence of environmental and physical factors on the probability of being hauled out, duration of haul-out bouts, and as factors associated with the start and end of a haulout. Location, season, hour, and interactions of location by year, season, hour, and sex significantly influenced haul-out probability, as did ice, weather, and vessels. Seals were more likely to be hauled out with greater ice availability during the middle of the day, and less likely to be hauled out if vessels were present. Cruise ships had the strongest negative effect; however, most vessel types negatively affected haul-out probability. Haul-out duration was longest in association with starting on incoming tides, clear skies, no precipitation, occurring in the middle of the day, and ending in the late afternoon or evening. End of haulouts was associated with increasing cloud cover, low ice availability, and vessel presence; large-sized tourism vessels or all-vessel-types combined were significant predictors of ending a haul-out bout. Probability of being hauled out was highest in June, during pupping season. Potential disturbances of harbor seals could be reduced, enabling longer resting times for seals and fewer interruptions for nursing pups, if vessels focused the majority of visits to glacial habitat to before or after the hours of 08:00-17:00 or, less optimally, 09:00-16:00.

No MeSH data available.


Dates of operation for time-lapse cameras.Cameras were used to detect vessel presence and assess environmental variables such as weather conditions and ice coverage. Horizontal bars indicate the range of dates (color-coded by camera site) that each time-lapse camera was functional at each remote monitoring station throughout the years of the study.
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pone.0125486.g002: Dates of operation for time-lapse cameras.Cameras were used to detect vessel presence and assess environmental variables such as weather conditions and ice coverage. Horizontal bars indicate the range of dates (color-coded by camera site) that each time-lapse camera was functional at each remote monitoring station throughout the years of the study.

Mentions: Cameras were functional for a total of 511 camera-days (Fig 2) during the study. A subset of 427 camera-days in 2009–10 were used in the analyses of vessel effects on seal behavior: 256 camera-days in 2009 (47 in inner Endicott, 44 in outer Endicott, and 165 in Tracy Arm) and 171 camera-days in 2010 (96 days in inner Endicott, 47 in outer Endicott, and 28 days in Tracy Arm). Cameras successfully detected AIS-equipped vessels entering and/or exiting the study areas an average of 44.2% of the time for both years, all vessel types, and all cameras combined (Table 2). AIS-vessel detection rates were higher in Endicott than in Tracy Arm and higher in both Arms in 2009 than in 2010. A higher proportion of AIS-equipped vessels entering Endicott were detected by the outer camera than the inner camera in 2009, while the opposite pattern occurred in 2010. Two factors likely affected these results; larger vessels that deploy smaller vessels to travel farther into the ice and those more vulnerable to damage from icebergs often stop at the edge of thick ice and may not venture far enough into the inlet to be detected with the inner Endicott camera. Additionally, we had greater camera coverage in inner Endicott in 2010 and problems with the outer Endicott camera that year when the camera at that site was repeatedly disturbed by bears. On several of those occasions the camera remained functional but the angle of view of outer Endicott was altered, changing from a long-range view down the arm in the direction of the mouth of the inlet to a short-range view across the arm, substantially reducing the potential for detecting passing vessels.


Factors Affecting Haul-Out Behavior of Harbor Seals (Phoca vitulina) in Tidewater Glacier Inlets in Alaska: Can Tourism Vessels and Seals Coexist?

Blundell GM, Pendleton GW - PLoS ONE (2015)

Dates of operation for time-lapse cameras.Cameras were used to detect vessel presence and assess environmental variables such as weather conditions and ice coverage. Horizontal bars indicate the range of dates (color-coded by camera site) that each time-lapse camera was functional at each remote monitoring station throughout the years of the study.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4446219&req=5

pone.0125486.g002: Dates of operation for time-lapse cameras.Cameras were used to detect vessel presence and assess environmental variables such as weather conditions and ice coverage. Horizontal bars indicate the range of dates (color-coded by camera site) that each time-lapse camera was functional at each remote monitoring station throughout the years of the study.
Mentions: Cameras were functional for a total of 511 camera-days (Fig 2) during the study. A subset of 427 camera-days in 2009–10 were used in the analyses of vessel effects on seal behavior: 256 camera-days in 2009 (47 in inner Endicott, 44 in outer Endicott, and 165 in Tracy Arm) and 171 camera-days in 2010 (96 days in inner Endicott, 47 in outer Endicott, and 28 days in Tracy Arm). Cameras successfully detected AIS-equipped vessels entering and/or exiting the study areas an average of 44.2% of the time for both years, all vessel types, and all cameras combined (Table 2). AIS-vessel detection rates were higher in Endicott than in Tracy Arm and higher in both Arms in 2009 than in 2010. A higher proportion of AIS-equipped vessels entering Endicott were detected by the outer camera than the inner camera in 2009, while the opposite pattern occurred in 2010. Two factors likely affected these results; larger vessels that deploy smaller vessels to travel farther into the ice and those more vulnerable to damage from icebergs often stop at the edge of thick ice and may not venture far enough into the inlet to be detected with the inner Endicott camera. Additionally, we had greater camera coverage in inner Endicott in 2010 and problems with the outer Endicott camera that year when the camera at that site was repeatedly disturbed by bears. On several of those occasions the camera remained functional but the angle of view of outer Endicott was altered, changing from a long-range view down the arm in the direction of the mouth of the inlet to a short-range view across the arm, substantially reducing the potential for detecting passing vessels.

Bottom Line: Cruise ships had the strongest negative effect; however, most vessel types negatively affected haul-out probability.End of haulouts was associated with increasing cloud cover, low ice availability, and vessel presence; large-sized tourism vessels or all-vessel-types combined were significant predictors of ending a haul-out bout.Potential disturbances of harbor seals could be reduced, enabling longer resting times for seals and fewer interruptions for nursing pups, if vessels focused the majority of visits to glacial habitat to before or after the hours of 08:00-17:00 or, less optimally, 09:00-16:00.

View Article: PubMed Central - PubMed

Affiliation: Alaska Department of Fish and Game, Division of Wildlife Conservation, Juneau, Alaska, United States of America.

ABSTRACT
Large numbers of harbor seals (Phoca vitulina) use habitat in tidewater glaciers in Alaska for pupping, breeding, and molting. Glacial fjords are also popular tourist destinations; however, visitation by numerous vessels can result in disturbance of seals during critical life-history phases. We explored factors affecting haul-out behavior of harbor seals at a glacial site frequented by tourism vessels. In 2008-10, we deployed VHF transmitters on 107 seals in Endicott Arm, Alaska. We remotely monitored presence and haul-out behavior of tagged seals and documented vessel presence with time-lapse cameras. We evaluated the influence of environmental and physical factors on the probability of being hauled out, duration of haul-out bouts, and as factors associated with the start and end of a haulout. Location, season, hour, and interactions of location by year, season, hour, and sex significantly influenced haul-out probability, as did ice, weather, and vessels. Seals were more likely to be hauled out with greater ice availability during the middle of the day, and less likely to be hauled out if vessels were present. Cruise ships had the strongest negative effect; however, most vessel types negatively affected haul-out probability. Haul-out duration was longest in association with starting on incoming tides, clear skies, no precipitation, occurring in the middle of the day, and ending in the late afternoon or evening. End of haulouts was associated with increasing cloud cover, low ice availability, and vessel presence; large-sized tourism vessels or all-vessel-types combined were significant predictors of ending a haul-out bout. Probability of being hauled out was highest in June, during pupping season. Potential disturbances of harbor seals could be reduced, enabling longer resting times for seals and fewer interruptions for nursing pups, if vessels focused the majority of visits to glacial habitat to before or after the hours of 08:00-17:00 or, less optimally, 09:00-16:00.

No MeSH data available.