Alex G. Kesaris, GISP

The California coastal stock of bottlenose dolphins (Tursiops truncatus) expanded its range north from the Southern California Bight, its historical range, into Central California coinci- dent with the 1982-1983 El Niño event. Since the late 1980s, bottlenose dolphin sightings north of Central California have been increasingly reported. To determine the present-day northern range limit for these dolphins, photo-identifica- tion efforts were carried out from 2007 to 2018 in San Francisco Bay and… Mehr zeigen

The California coastal stock of bottlenose dolphins (Tursiops truncatus) expanded its range north from the Southern California Bight, its historical range, into Central California coinci- dent with the 1982-1983 El Niño event. Since the late 1980s, bottlenose dolphin sightings north of Central California have been increasingly reported. To determine the present-day northern range limit for these dolphins, photo-identifica- tion efforts were carried out from 2007 to 2018 in San Francisco Bay and nearby coastal waters during which 84 individuals were identified. The results demonstrate a significant range expan- sion along the Northern California coast at least as far as Sonoma County (38.7o N). Comparisons with photo-identification catalogs compiled south of San Francisco from 1981 to 2015 revealed that 92% of the 84 dolphins were matched to Monterey Bay (n = 77), Santa Barbara (n = 27), Santa Monica Bay (n = 29), Orange County (n = 9), Corona Del Mar (n = 2), San Diego (n = 31), and Ensenada, Mexico (n = 1). Many of the 84 dolphins (54%) showed long-range movements across the stock’s range between the Southern California Bight and the San Francisco Bay Area. The greatest movement distance recorded was by two individuals first observed in San Diego, California, in the 1980s and subsequently in Puget Sound, Washington (47o N), in 2017, setting a coastal bottlenose dolphin long-distance move- ment record of at least 2,500 km. Weniger anzeigen

My contributions to analysis and integration of this 33-year dolphin photo-ID catalog are acknowledged by authors D. W. Weller and R. H. Defran. My analyst work included: (1) SDSU: field data collection 1989, photo-ID analysis of 1984-89 data; (2) Scripps: field data collection during 2010-11; (3) Sustenant Consulting: field data collection 2012; digital photo-ID analysis and integration of 1981-2014 data for San Diego, San Quintin, Ensenada; Orange County, and Santa Barbara, resulting in… Mehr zeigen

My contributions to analysis and integration of this 33-year dolphin photo-ID catalog are acknowledged by authors D. W. Weller and R. H. Defran. My analyst work included: (1) SDSU: field data collection 1989, photo-ID analysis of 1984-89 data; (2) Scripps: field data collection during 2010-11; (3) Sustenant Consulting: field data collection 2012; digital photo-ID analysis and integration of 1981-2014 data for San Diego, San Quintin, Ensenada; Orange County, and Santa Barbara, resulting in catalog of 1,291 dolphins; editing of catalog intro pages; and, production of photo catalog database and pages for 1,291 dolphins.

This catalog presents identification photographs of 1,291 Pacific coast bottlenose dolphins (Tursiops truncatus) obtained during dedicated research surveys carried out between 1981 and 2014 in five coastal study areas: Ensenada, Mexico; San Quintín, Mexico; San Diego, CA; Orange County, CA; and Santa Barbara, CA. These images were primarily collected by the Southwest Fisheries Science Center (National Marine Fisheries Service, NMFS), the Cetacean Behavior Laboratory (San Diego State University, CBL), and Scripps Whale Acoustics Lab (Scripps Institution of Oceanography, SIO). Some images were provided to the CBL by collaborators in the U.S. and Mexico.

The overarching objectives of making this catalog publically available are twofold: (1) to facilitate regional and international cooperation and collaboration between current and future research groups collecting data on Pacific coast bottlenose dolphins; and (2) to provide an individual identification numbering scheme and standardized images of Pacific coast bottlenose dolphins that can be used for comparison by other research groups and organizations. This catalog is available on request in PDF format and online at SWFSC https://swfsc.noaa.gov/ as part of the Cetacean Health and Life History Program and OBIS SEAMAP http://seamap.env.duke.edu/ as part of the California Dolphin Online Catalog (CDOC). Weniger anzeigen

The occurrence, distribution, group size and abundance of California coastal stock bottlenose dolphins (Tursiops truncatus) were assessed during a boat-based photo-identification study between November 2009 and April 2011 off San Diego, California. A total of 31 photographic surveys were completed and dolphin groups were encountered on 30 (97%) of them. A total of 115 dolphin groups were observed and 346 individuals photographically identified. All groups were sighted within approximately 1-2… Mehr zeigen

The occurrence, distribution, group size and abundance of California coastal stock bottlenose dolphins (Tursiops truncatus) were assessed during a boat-based photo-identification study between November 2009 and April 2011 off San Diego, California. A total of 31 photographic surveys were completed and dolphin groups were encountered on 30 (97%) of them. A total of 115 dolphin groups were observed and 346 individuals photographically identified. All groups were sighted within approximately 1-2 km of shore. The mean group size was 8.2 (SE = 0.6) and the average number of dolphins and groups encountered per survey was 31.5 (SE = 4.2) and 3.9 (SE = 0.5), respectively. Low resighting rates (mean = 2.2; SE = 0.8) and an ever-increasing rate of discovery for previously unidentified dolphins were observed. Strikingly, 258 of the 346 identified dolphins during this study were not represented in the prior 1981-2005 photo-identification catalog for San Diego. Dolphins were considered “marked” if they had two or more dorsal fin nicks. Mark-recapture analysis using POPAN as well as closed models in RMark produced abundance estimates of 515 marked dolphins (95% CI = 470-564, SE = 24.0) and 453 marked dolphins (95% CI = 411-524, SE = 28.1), respectively. Differences in encounter rates, group size and number of groups encountered per survey during the 2009-2011 study were apparent when compared to earlier studies in the same area between 1984 and 2005. Weniger anzeigen

Current survey indices used in annual stock assessments to manage the federal Pacific sardine (Sardinops sagax caerulea) fishery do not include nearshore sardine biomass in southern California waters. This survey uses direct observer estimates of sardine biomass in nearshore and offshore waters of the Southern California Bight to calculate an index of relative abundance. Surveys have been conducted since summer of 2012 and have continued through the spring and summer 2013 seasons. Aerial… Mehr zeigen

Current survey indices used in annual stock assessments to manage the federal Pacific sardine (Sardinops sagax caerulea) fishery do not include nearshore sardine biomass in southern California waters. This survey uses direct observer estimates of sardine biomass in nearshore and offshore waters of the Southern California Bight to calculate an index of relative abundance. Surveys have been conducted since summer of 2012 and have continued through the spring and summer 2013 seasons. Aerial identifications of fish school species have been validated using boat sampling of aerial sightings and demographic information obtained from collected samples. Additionally, habitat analyses compared sardine distribution with environmental variables (sea surface temperature and chlorophyll a concentrations). Weniger anzeigen