Introduction & Objectives

The United States (US) Navy uses the Southern California (SOCAL) portion of the Hawaii-Southern California Training and Testing area, a collection of nearshore and offshore training areas that include much of the navigable water from Santa Barbara Island, California, to northern Baja California, Mexico, and extending several hundred miles to the west. It is among one of the most heavily used tactical training areas in the world, and is used for a variety of aerial, surface, and subsurface exercises. The US Navy has funded directed studies on cetacean occurrence on SOAR since 2006. 

The primary focus of these studies is to support long-term surveys of Cuvier’s beaked whales and fin whales using photo-identification (photo-ID) and genetics to elucidate population size, structure, and trends, which can in turn provide a particularly robust basis for assessing population-level impacts of Navy training. These efforts have included demographic assessments, foraging ecology, and behavioral responses to MFAS for several key species which often provide insights into cumulative impacts that might otherwise not show up in acoustic or visual density data.

Presently, the overall scientific questions addressed by the Navy’s Integrated Comprehensive Monitoring Program (henceforth “Pacific Fleet Monitoring”) at SOAR, in cooperation with M3R, are the following:

What is the seasonal occurrence and abundance/density estimations of beaked whales and Endangered Species Act (ESA) listed baleen whales within the Navy’s SOCAL?

Does exposure to sonar or explosives impact the long-term fitness and survival of individuals or the population, species, or stock (with focus on blue whale (Balaenoptera musculus), fin whale, humpback whale (Megaptera novaeangliae), Cuvier’s beaked whale, and other regional beaked whale species)?

What are the baseline population demographics, vital rates, and movement patterns for Cuvier’s beaked whales and fin whales?

In addition to beaked whales and fin whales, the species, group size, and basic behavior is recorded for all cetaceans encountered. For some species, particularly those that are data deficient, we may also collect photo-ID images, biopsy samples, and deploy Low Impact Minimally Percutaneous External-electronics Transmitting (LIMPET) tags.

Technical Approach

satellite tagging and photo-ID data

Surveys were conducted using a 6.5 to 7.5-meter (m) rigid-hulled inflatable boat (RHIB), powered by two outboard motors and equipped with a raised bow pulpit. When SOAR was available, staff from the Naval Undersea Warfare Center’s (NUWC) M3R program would monitor hydrophones from the ROC on North Island in San Diego and direct the RHIB via radio or satellite phone into areas where marine mammal vocalizations were detected. 

All photos collected during surveys were reviewed, and image metadata were updated with sighting and individual information using ACDSee Pro image management software. Best-of sighting identification photographs of fin whales and beaked whales from each annual sampling period were combined with opportunistic contributions from citizen science and collaborating researchers, internally reconciled, and then compared to our existing photo-ID catalogs, using methods previously described to build photographic sighting histories. 

Progress & Results

Publications:

Curtis, K.A., Falcone, E.A., Schorr, G.S., Moore, J.E., Moretti, D.J., Barlow, J., and Keene, E.  (2020)  Abundance, survival, and annual rate of change of Cuvier’s beaked whales (Ziphius cavirostris) on a Navy sonar range.  Marine Mammal Science.  https://doi.org/10.1111/mms.12747

Barlow, J, Schorr, GS, Falcone, EA, Morretti, D. 2020. Variation in dive behavior of Cuvier's beaked whales with seafloor depth, time-of-day, and lunar illumination. Mar Ecol Prog Ser 644:199-214. https://doi.org/10.3354/meps13350

Keen EM, Scales KL, Rone BK, Hazen EL, Falcone EA and Schorr GS. 2019. Night and Day: Diel Differences in Ship Strike Risk for Fin Whales (Balaenoptera physalus) in the California Current System. Front. Mar. Sci. 6:730. doi: 10.3389/fmars.2019.00730

Keen, E.M., Falcone, E.A., Andrew, R.D., Schorr, G.S. 2019. Diel dive behaviors of fin whales (Balaenoptera physalus) in the Southern California Bight. Aquatic Mammals, 45(2), 2330243. DOI 10.1578/AM>45.2.2019.333

Scales, K.L., Schorr G.S., Hazen E.L., Bogard S.J., Miller P.I., Andrews R.D., Zerbini A.N., Falcone, E.A. 2017. Should I stay or should I go? Modelling year-round habitat suitability and drivers of residency for fin whales in the California Current. Diversity and Distributions 2017;00-1-12. https://doi./org/10.1111/ddi.12611

Schorr, G.S., Falcone, E.A., Moretti, D.J., Andrews, R.D., 2014. First Long-Term Behavioral Records from Cuvier’s Beaked Whales (Ziphius cavirostris) Reveal Record-Breaking Dives. PLoS ONE 9, e92633. doi:10.1371/journal.pone.0092633

Falcone, E.A., G.S. Schorr, A.B. Douglas, J. Calambokidis, E. Henderson, M.F. McKenna, J. Hildebrand, and D. Moretti. 2009. Sighting characteristics and photo-identification of Cuvier’s beaked whales (Ziphius cavirostris) near San Clemente Island, California: A key area for beaked whales and the military? 
Marine Biology 156:2631-2640.