Author: Mark S. Lowry
Publisher:
ISBN:
Category : Harbor seal
Languages : en
Pages : 38
Book Description
An aerial photographic census of Pacific harbor seals (Phoca vitulina richardsi) was conducted in California 18 May-19 July 2004 to document the number of seals hauled out during the molt period. To compensate for latitudinal differences in the timing of the molt, the state of California was divided into three sections and each section was surveyed on different dates. The three sections were: (1) Channel Islands and mainland coast of southern California from the U.S./Mexico border to Pismo Beach, (2) central California from Pismo Beach to Point Reyes and San Francisco Bay estuary, and (3) northern California from Point Reyes to the California/Oregon border. Aerial photographic surveys at the Channel Islands and the mainland coast of southern California occurred during the afternoon high-low tide cycle on 18-20 May and 1-3 June at tide levels of 0.43 m to 0.88 m and 0.40 m to 0.73 m, respectively. Surveys in central California occurred during the low-low tide cycle at tide levels of -0.03 m to 0.49 m on 22-25 June. Surveys in northern California occurred during the low-low tide cycle at tide levels of -0.34 m to 0.43 m on 5-9 July and 18-19 July (except at South Humboldt Bay, Eel River, and Cape Mendocino where tide levels were 0.49 m to 0.52 m, 0.89 m, and 0.98 m, respectively). Color transparency photographs of harbor seals were taken with a 126-mm-format camera equipped with image motion compensation. The latitude and longitude of each photograph was recorded by linking the camera to a computer and Global Positioning System (GPS). Two to three observers searched for hauled-out seals. Seals were photographed as the aircraft was flown over the coastline at 213 m (700 ft). A total of 563 haulout sites within the state of California were found during complete surveys conducted at a mean tide level of 0.28 m (-0.46 m to 0.98 m). At the Channel Islands there were 4,344 seals counted onshore, along the mainland coast of California and San Francisco Bay estuary there were 21,989, and statewide there were 26,333. The mainland coast of California was stratified into nineteen 0.5-degree latitude segments with counts from the San Francisco Bay estuary making up the twentieth stratum. Stratum 37.50E to 37.99E had the most seals (n = 3,360) and the most seals at a single haulout site (n = 939). Stratum 40.50E to 40.99E had the highest median (104) and mean (178.4) number of seals per haulout. Of the eight Channel Islands in southern California, Santa Cruz Island had the most seals (n =1,102) and Santa Barbara Island the fewest (n = 12). Total 2004 counts were greater than 2002 counts at mainland sites, but counts at the Channel Islands were relatively stable.
Pacific Harbor Seal, Phoca Vitulina Richardsi, Census in California During May-July 2004
Author: Mark S. Lowry
Publisher:
ISBN:
Category : Harbor seal
Languages : en
Pages : 38
Book Description
An aerial photographic census of Pacific harbor seals (Phoca vitulina richardsi) was conducted in California 18 May-19 July 2004 to document the number of seals hauled out during the molt period. To compensate for latitudinal differences in the timing of the molt, the state of California was divided into three sections and each section was surveyed on different dates. The three sections were: (1) Channel Islands and mainland coast of southern California from the U.S./Mexico border to Pismo Beach, (2) central California from Pismo Beach to Point Reyes and San Francisco Bay estuary, and (3) northern California from Point Reyes to the California/Oregon border. Aerial photographic surveys at the Channel Islands and the mainland coast of southern California occurred during the afternoon high-low tide cycle on 18-20 May and 1-3 June at tide levels of 0.43 m to 0.88 m and 0.40 m to 0.73 m, respectively. Surveys in central California occurred during the low-low tide cycle at tide levels of -0.03 m to 0.49 m on 22-25 June. Surveys in northern California occurred during the low-low tide cycle at tide levels of -0.34 m to 0.43 m on 5-9 July and 18-19 July (except at South Humboldt Bay, Eel River, and Cape Mendocino where tide levels were 0.49 m to 0.52 m, 0.89 m, and 0.98 m, respectively). Color transparency photographs of harbor seals were taken with a 126-mm-format camera equipped with image motion compensation. The latitude and longitude of each photograph was recorded by linking the camera to a computer and Global Positioning System (GPS). Two to three observers searched for hauled-out seals. Seals were photographed as the aircraft was flown over the coastline at 213 m (700 ft). A total of 563 haulout sites within the state of California were found during complete surveys conducted at a mean tide level of 0.28 m (-0.46 m to 0.98 m). At the Channel Islands there were 4,344 seals counted onshore, along the mainland coast of California and San Francisco Bay estuary there were 21,989, and statewide there were 26,333. The mainland coast of California was stratified into nineteen 0.5-degree latitude segments with counts from the San Francisco Bay estuary making up the twentieth stratum. Stratum 37.50E to 37.99E had the most seals (n = 3,360) and the most seals at a single haulout site (n = 939). Stratum 40.50E to 40.99E had the highest median (104) and mean (178.4) number of seals per haulout. Of the eight Channel Islands in southern California, Santa Cruz Island had the most seals (n =1,102) and Santa Barbara Island the fewest (n = 12). Total 2004 counts were greater than 2002 counts at mainland sites, but counts at the Channel Islands were relatively stable.
Publisher:
ISBN:
Category : Harbor seal
Languages : en
Pages : 38
Book Description
An aerial photographic census of Pacific harbor seals (Phoca vitulina richardsi) was conducted in California 18 May-19 July 2004 to document the number of seals hauled out during the molt period. To compensate for latitudinal differences in the timing of the molt, the state of California was divided into three sections and each section was surveyed on different dates. The three sections were: (1) Channel Islands and mainland coast of southern California from the U.S./Mexico border to Pismo Beach, (2) central California from Pismo Beach to Point Reyes and San Francisco Bay estuary, and (3) northern California from Point Reyes to the California/Oregon border. Aerial photographic surveys at the Channel Islands and the mainland coast of southern California occurred during the afternoon high-low tide cycle on 18-20 May and 1-3 June at tide levels of 0.43 m to 0.88 m and 0.40 m to 0.73 m, respectively. Surveys in central California occurred during the low-low tide cycle at tide levels of -0.03 m to 0.49 m on 22-25 June. Surveys in northern California occurred during the low-low tide cycle at tide levels of -0.34 m to 0.43 m on 5-9 July and 18-19 July (except at South Humboldt Bay, Eel River, and Cape Mendocino where tide levels were 0.49 m to 0.52 m, 0.89 m, and 0.98 m, respectively). Color transparency photographs of harbor seals were taken with a 126-mm-format camera equipped with image motion compensation. The latitude and longitude of each photograph was recorded by linking the camera to a computer and Global Positioning System (GPS). Two to three observers searched for hauled-out seals. Seals were photographed as the aircraft was flown over the coastline at 213 m (700 ft). A total of 563 haulout sites within the state of California were found during complete surveys conducted at a mean tide level of 0.28 m (-0.46 m to 0.98 m). At the Channel Islands there were 4,344 seals counted onshore, along the mainland coast of California and San Francisco Bay estuary there were 21,989, and statewide there were 26,333. The mainland coast of California was stratified into nineteen 0.5-degree latitude segments with counts from the San Francisco Bay estuary making up the twentieth stratum. Stratum 37.50E to 37.99E had the most seals (n = 3,360) and the most seals at a single haulout site (n = 939). Stratum 40.50E to 40.99E had the highest median (104) and mean (178.4) number of seals per haulout. Of the eight Channel Islands in southern California, Santa Cruz Island had the most seals (n =1,102) and Santa Barbara Island the fewest (n = 12). Total 2004 counts were greater than 2002 counts at mainland sites, but counts at the Channel Islands were relatively stable.
Harbor Seal, Phoca Vitulina Richardsi, Census in California, June 2-5, 30 and July 1, 1986
Author: Doyle A. Hanan
Publisher:
ISBN:
Category : Harbor seal
Languages : en
Pages : 86
Book Description
Publisher:
ISBN:
Category : Harbor seal
Languages : en
Pages : 86
Book Description
Harbor Seal, Phoca Vitulina Richardsi, Census in California, May-June 1987
Author: Doyle A. Hanan
Publisher:
ISBN:
Category : Harbor seal
Languages : en
Pages : 60
Book Description
Publisher:
ISBN:
Category : Harbor seal
Languages : en
Pages : 60
Book Description
Harbor Seal, Phoca Vitulina Richardsi, Census in California, May-June, 1993
Author: Doyle A. Hanan
Publisher:
ISBN:
Category : Harbor seal
Languages : en
Pages : 100
Book Description
Publisher:
ISBN:
Category : Harbor seal
Languages : en
Pages : 100
Book Description
Estimating Population Size of Pacific Harbor Seals (Phoca Vitulina Richardsi) at Children's Pool Beach in La Jolla, California, Using Photo-identification
Author: Traci A. Linder
Publisher:
ISBN: 9781267079831
Category :
Languages : en
Pages : 36
Book Description
Children's Pool Beach in La Jolla, CA is a Pacific harbor seal (Phoca vitulina richardsi) rookery at the center of a large legal controversy. Due to the heated contention surrounding this rookery, very few scientific studies have been done on the population of harbor seals that use this haul-out site. Maximum daily haul-out counts rarely exceed 200, and management decisions have been framed around the assumption of a largely resident population of no more than approximately 250 seals. In this study I used photo-identification and mark-recapture methods to estimate the total population of Pacific harbor seals that used Children's Pool Beach as a haul-out site during January - October 2008. I photographed the ventral surfaces of adult harbor seals at Children's Pool Beach, and then entered each good to high quality photograph into an interactive computer-assisted photograph-matching system for individual identification. Each individual identification was confirmed by both a trained volunteer and myself, resulting in a 4% visual matching error rate. After analysis concluded, 480 unique adult harbor seals were individually identified after applying the 4% visual matching error rate. Abundance estimation was calculated using the Chapman-Petersen capture-recapture model. My calculations yielded a population estimate of 596 individuals during January - October 2008, which is two to three times larger than previously believed. These findings suggest a population that is at least partially open with considerable coastal movement, suggesting that Children's Pool Beach is potentially part of a regional network of interconnected haul-out site.
Publisher:
ISBN: 9781267079831
Category :
Languages : en
Pages : 36
Book Description
Children's Pool Beach in La Jolla, CA is a Pacific harbor seal (Phoca vitulina richardsi) rookery at the center of a large legal controversy. Due to the heated contention surrounding this rookery, very few scientific studies have been done on the population of harbor seals that use this haul-out site. Maximum daily haul-out counts rarely exceed 200, and management decisions have been framed around the assumption of a largely resident population of no more than approximately 250 seals. In this study I used photo-identification and mark-recapture methods to estimate the total population of Pacific harbor seals that used Children's Pool Beach as a haul-out site during January - October 2008. I photographed the ventral surfaces of adult harbor seals at Children's Pool Beach, and then entered each good to high quality photograph into an interactive computer-assisted photograph-matching system for individual identification. Each individual identification was confirmed by both a trained volunteer and myself, resulting in a 4% visual matching error rate. After analysis concluded, 480 unique adult harbor seals were individually identified after applying the 4% visual matching error rate. Abundance estimation was calculated using the Chapman-Petersen capture-recapture model. My calculations yielded a population estimate of 596 individuals during January - October 2008, which is two to three times larger than previously believed. These findings suggest a population that is at least partially open with considerable coastal movement, suggesting that Children's Pool Beach is potentially part of a regional network of interconnected haul-out site.
Harbor Seal, Phoca Vitulina Richardsi, Census in California, May-June, 1991
Author: Doyle A. Hanan
Publisher:
ISBN:
Category : Harbor seal
Languages : en
Pages : 68
Book Description
Publisher:
ISBN:
Category : Harbor seal
Languages : en
Pages : 68
Book Description
Harbor Seal, Phoca Vitulina Richardsi, Census in California, May-June, 1992
Author: Doyle A. Hanan
Publisher:
ISBN:
Category : Harbor seal
Languages : en
Pages : 53
Book Description
Publisher:
ISBN:
Category : Harbor seal
Languages : en
Pages : 53
Book Description
Harbor Seal, Phoca Vitulina Richardsi, Census in California, May-June, 1989
Author: Doyle A. Hanan
Publisher:
ISBN:
Category : Harbor seal
Languages : en
Pages : 61
Book Description
Publisher:
ISBN:
Category : Harbor seal
Languages : en
Pages : 61
Book Description
Annual Report of the Marine Mammal Commission
Author: United States. Marine Mammal Commission
Publisher:
ISBN:
Category : Marine mammals
Languages : en
Pages : 300
Book Description
Publisher:
ISBN:
Category : Marine mammals
Languages : en
Pages : 300
Book Description