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L.A. Dolphin Project 2


dolphin and seabird







Looking at the existing scientific literature it's rare to find any detailed description of dolphin, sea lion and seabird aggregations at sea due to the complexity of following and recording the behavior of these fast-moving and widespread animals from the surface. The Santa Monica Bay, in California is an excellent site for the study of local aggregations between these marine species due to its relative shelter from open ocean conditions and the presence of three submarine canyons that provide nutrient rich feeding areas.

California sea lions in the Santa Monica Bay
California sea lions “porpoising” offshore in the Santa Monica Bay

Overlapping prey and habitat provides opportunities to study species aggregations

The overlapping of prey and habitat for sea lions, seabirds and three dolphin species (bottlenose dolphins, short-beaked common dolphins and long-beaked common dolphins) in Santa Monica Bay, California, offers an opportunity to learn more about these animals and whether either, any or all derive some benefit from aggregation with other species.

An OCS research study conducted between 1997-2001 investigated whether these aggregations were food-based, and found that sea lions actually take advantage of the superior ability of dolphins to echolocate food in common foraging grounds (see publications).

How is research data collected in this study?

Utilizing a variety of data accumulation methods including photo-identification of individuals, seabird recognition, cetacean focal group behavioral descriptions, bioacoustic recording, fish scale collection for prey identification, and correlated surface and underwater video filming, we currently aim to shed more light onto the meaning and dynamics of marine mammal and seabird aggregations.

dolphin feeding off Pt.Dume LADP researchers identifying seabirds
Feeding off Pt. Dume, California   LADP researchers
identifying seabird species

Project Objectives

The current phase of this project is to expand upon our previous study to:

  • Better understand the behavioral ecology of these species during foraging and feeding activities both from the surface and underwater.
  • Investigate the role played by seabirds during search and pursuit of prey and feeding activities of the mixed species groups.

Conservation and Management Implications

The Santa Monica Bay, California is an excellent site for the study of local aggregations between these marine species due to the presence of three submarine canyons and other bathymetric features that provide nutrient rich feeding areas to these animals and the species they feed upon. Monitoring these top-predator species and changes in their occurrence and distribution can provide useful data to mitigate threats to them and other organisms as well.

Some of these bathymetric features are located inside the boundaries of the newly established Marine Protected Areas. Data on these animals' aggregations may provide useful information to guide management and expansion of existing MPAs, and perhaps push the interconnectivity of existing MPA networks.




Is there a conflict between California sea lions and recreational fishing activities?

California sea lions (Zalophus californianus) are regular and year-round inhabitants off Southern California and their population has been increasing since monitoring began in 1975. In the last decade, this population growth has intensified the possibility of conflict between sea lions and fishing activities. Sea lions are known to depredate from both commercial and recreational fishing activities, causing decreases to fish catch and damage to fishing gear. The overall scope of this project is to better understand recreational fishing community opinions and concerns on a variety of current and critical issues in the hope of finding ways to improve communication between anglers, policymakers, and conservationists.


Southern California has shown the highest incidence of depredation by sea lions in the state, yet qualitative and quantitative data is relatively scarce for the area. Sea lion depredation has been studied mainly in commercial fisheries, with only a few studies aimed to recreational fisheries. Further, California sea lion interaction with onshore marine fishing activities has not been previously investigated.

Sea lions are protected under the Marine Mammal Protection Act of 1972, which makes it illegal for fishermen to kill or seriously harass these animals to prevent depredation. Current deterrent devices have been proven to be ineffective, and the present trend of population growth is likely to lead to more conflict between anglers and these pinnipeds.

OCS volunteer Amber interviews a fisherman at Venice pier


Maintaining plentiful fish stocks is a shared goal - but is regulating fisheries creating conflicts?

Regulating fisheries involves economic costs borne by anglers. These costs can lead to conflicts between anglers, regulatory agencies and scientists, despite the fact that all parties share a common goal of maintaining plentiful fish stocks. Data shows that when socioeconomic costs are considered and anglers are consulted during the planning stages of regulatory legislation, that legislation is more effective. It is becoming increasingly recognized that angler experience can be a useful asset for marine conservation planning. In Southern California, Marine Protected Areas (MPAs) were recently implemented in the hope of restoring and protecting dwindling local fisheries. These areas restrict fishing efforts, and this cost to anglers has been a contentious issue since the implementation of the MPAs, deepening the gap between fishing interests and environmental/conservation interests.

Data Collection Techniques

Four teams of at least two persons are assigned to various areas to take opinion surveys both in English and Spanish. The surveys are conducted as an interview where OCS personnel ask prepared questions and record answers. Surveys are anonymous and no personal data is taken on survey participants. All data collected will be used for scientific and/or educational purposes only.

Surveys are carried out at boat launch ramps, fishing piers and commercial passenger fishing vessel (CPFV) landings in popular fishing ports from Ventura/Channel Islands to San Diego. The objective is to concentrate efforts in specific ports to correlate with the respective percentage of total recreational fishing traffic in the region.

The scope is to collect a total of 300+ interviews, with an even effort along the Southern California Coast and among locations.

Project Objectives

The recreational fishing community in Southern California is an under-utilized source for information and potential solutions to management and legislative problems. The RFSP utilizes personal interviews, conducted in the field with recreational anglers and CPFV crews in Southern California to gather data on:

  • Determining how widespread sea lion depredation is and what level of impact it has on the recreational fisheries in Southern California
  • Current knowledge and usage of sea lion deterrent devices and potential demand for new technologies
  • Current opinions of recreational fishers towards sea lions
  • Current opinions of recreational fishers towards dolphins
  • Awareness of current legislation & policy affecting recreational fishing (MLPA, Marine Protected Areas, and the Marine Mammal Protection Act of 1972)
  • Fishers' opinions about the effectiveness of legislation
  • Perceptions and opinions on possible conflict between fisher interests and environmental/conservation interests
  • Suggestions on ways to address and resolve such conflict

Why is this project important?

The overall scope of this project is to gauge recreational fishing community outlooks on a variety of current and critical issues in the hope of finding ways to improve communication between anglers, policymakers and conservationists.



We are currently continuing our year-round monitoring of cetaceans along their coastal corridors and within and outside the boundaries of the coastal Marine Protected Areas (MPAs) in Santa Monica Bay, California. Monitoring species like cetaceans is an essential tool to:

  • Guide the planning, management, and expansion of existing MPAs
  • Justify and promote new MPAs
  • Push the interconnectivity of MPA networks



We are currently searching for funding to continue this study.
Actively support us by making a tax-deductible donation:



mixed species aggregation
Dolphins and seabirds in the Santa Monica Bay

Background - the significance of transit corridors for cetacean conservation

The waters off Los Angeles are rich in cetaceans, including threatened & endangered species like humpback and blue whales, which forage in the bay and within the local coastal MPAs. Upwelling areas near submarine canyons and escarpments in the bay are foraging hotspots and critical habitats for a variety of cetaceans as well as other species (e.g., seabirds, fish, pinnipeds).

These coastal regions also serve as regular transit corridors used by cetaceans to move between foraging hotspots. Corridors are often ignored in the design of MPAs, including those in the bay, but they are critically important to long-term population viability of these species. Protecting these migratory/movement corridors, and including them in the design, implementation and expansion of MPAs and MPA networks, is essential to ensure that the connection between critical habitats remain unbroken.

Top predators like coastal bottlenose dolphins, which are regular inhabitants of the Santa Monica Bay (SMB) and use the area as both foraging hotspot and corridor, are now considered worldwide to be key indicators and sentinels of the status and health of coastal habitats. Long-term population monitoring of these dolphins provides a powerful tool for understanding habitat use as well as tracking the progression of poorly understood diseases that may impact both cetacean and human health.

Researcher using GIS harbor seal in Malibu
Researcher using GIS to log dolphin positions   Harbor seal atop a rock in Malibu

How is data collected?

This study builds on over a decade of ecological baseline data collected by OCS utilizing already established field methodologies, existing equipment, trained research staff, and ongoing scientific collaborations with other researchers, NGO's and government agencies.

Regular boat surveys are conducted three times per month to collect systematic data on occurrence, distribution, temporal (seasonal and annual) variability, and behavior of cetaceans, as well as to monitor animal health and potential threats to them (e.g., human disturbance, marine debris, etc.), both within and outside MPA boundaries in the study area of Santa Monica Bay.

OCS research survey team follows pre-determined transects and employs GIS technology and up-to-date software to collect data and measure behavioral responses.

common dolphins

A school of common dolphins leaping off California

Project Objectives

Data on cetaceans collected along coastal corridors as well as within and outside the boundaries of the local coastal MPAs can be extremely useful for policy recommendations regarding both newly established and future protected areas.

Data on distribution, occurrence, frequency and behavior of cetaceans that frequent the SMB, where human activities and marine life overlap, will:

  • Identify aggregations of cetaceans and/or hotspots for dolphins and whales
  • Define critical marine mammal habitats near and within the newly established MPAs
  • Provide data for implementation of an overall management approach to ensure that critical habitats remain healthy and supportive of marine life
  • Establish priorities for protection
  • Create a better understanding of spatial relationships between the animals, ecological processes, and human activities
  • Identify and help control human threats to cetaceans (e.g., pollution, algal blooms, marine traffic/recreational fishing, whale watching).
  • Track the progression of poorly understood diseases relevant to both human and dolphin health
  • Help raise public support for better protection of cetaceans and the possible expansion of local MPAs using dolphins and whales as symbolic species
  • Provide guidance on enforcing, managing and evaluating the expansion of existing MPAs and help identify areas outside the current MPAs that may deserve consideration
  • Facilitate stronger collaborations with other members of the MPA network along the California coast.


We believe that MPA designation must be dynamic and that management needs to be adaptive. Research, monitoring, and evaluation must be conducted on a regular basis and, if possible, set within a more regional context. This is particularly important today, in face of climate change and other environmental issues.

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