Distribution and Demographics of Marine Mammals in SOCAL Through Photo-Identification, Genetics, and Satellite Telemetry

Abstract

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. SPONSOR/MONITOR'S REPORTMonterey, CA 93943-5122 NUMBER(S)NPS-OC-14-005CR DISTRIBUTION / AVAILABILITY STATEMENTApproved for public release; distribution is unlimited. SUPPLEMENTARY NOTESThe views expressed in this report are those of the authors and do not reflect the official policy or position of the Department of Defense or the US Government. ABSTRACTThis report summarizes data collected during small-vessel surveys for cetaceans in the Southern California Bight (SCB), with a focus on the Southern California Offshore Range Complex (SCORE), from June 2010-January 2014. Detailed annual progress reports were prepared after each survey year through 2013 and are available online through the Naval Postgraduate School. This final report emphasizes analyses that combine data across study years, particularly with respect to two focal species: Cuvier's beaked (Ziphius cavirostris, Zc) and fin (Balaenoptera physalus, Bp) whales. 18 cetacean species were encountered in surveys based at SCORE, and several previously documented seasonal trends in species occurrence were confirmed. Bp were sighted in every month surveyed, Zc in all but one, suggesting both are present year-round. Preliminary mark-recapture abundance estimates from photo-identification data suggest both species have local populations in the low hundreds. Both photo-identification and telemetry data suggest Zc exhibit a degree of basin-specific site fidelity within the SCB. Many Bp also appear to preferentially remain within the SCB year-round, with increased use of nearshore waters in fall and winter. A subset of 688 hours of Zc diving behavior from periods without Mid-Frequency Active Sonar use in the area showed that the behavior of these whales was similar to that of the larger dataset (including sonar exposure), and confirms previous observations that Zc here appear to forage less often than whales in other regions, and that sonar exposure is unlikely to be the primary driver of these regional differences, though some exposures may cause foraging disruption. Future research will seek to further elucidate the relationship between behavioral patterns and sonar use in the area. SUBJECT TERMS

Global distribution ofRisso's dolphinGrampus griseus: a review and critical evaluation

“…This animal moved in waters with an average depth of 548 m and performed dives of up to 400-500 m (Wells et al 2009). Three Risso's dolphins tracked in southern California moved in waters with an average depth of 900-974 m (Falcone & Schorr 2011). This does not mean the animals do not occur elsewhere, and certainly there are records of the species in deep oceanic waters and in shallow waters a great distance from the shelf edge.…”

Global distribution of fin whalesBalaenoptera physalusin the post‐whaling era (1980–2012)

“…Specifically, movements have been observed between the Southern Ocean and the coasts of Chile, Brazil and South Africa (30–70°S; Brown ), between the Azores and Iceland (40–65°N; Silva et al. ), between the northwest coast of Mexico (central Baja California) and the west coast of the USA (northern California, 26–40°N; Falcone & Schorr ), between the Faroes and westward of the Bay of Biscay (46–62°N; Mikkelsen et al. ), and along the coasts of the western and eastern North Pacific (30–60°N; Mizroch et al.…”

“…). Recent satellite tagging conducted off the south‐western coast of the USA found that fin whales aggregated along the coast during autumn and winter, dispersed farther offshore during spring and summer, and used several areas year‐round (Falcone & Schorr ). None of the tagged fin whales travelled south of approximately 26°N (Falcone & Schorr ).…”

Abundance, survival, and annual rate of change of Cuvier's beaked whales (Ziphius cavirostris) on a Navy sonar range

“…Whales were assigned to age and sex classes using a combination of behavioral (e.g., mother-calf associations), genetic (for individuals that were biopsy sampled during the study), and appearance data (e.g., erupted teeth, scarring rates) following methods described in Rosso, Balardini, Moulins, and Würtz (2011) and Coomber, Moulins, Tepsich, and Rosso (2016). Individual sighting histories were created through the comparison of captured individuals in each sighting to the accrued catalog, as described in Falcone and Schorr (2014).…”