California Cooperative Oceanic Fisheries Investigations (CalCOFI)
The Channel Islands National Marine Sanctuary (CINMS)
The Channel Islands National Marine Sanctuary (CINMS) is a region in southern California off the coast of Ventura and Santa Barbara. CINMS is 1,252-square-nautical-mile portion of the Santa Barbara Channel that encompasses the waters that surround Anacapa, Santa Cruz, Santa Rosa, San Miguel, and Santa Barbara Islands, extending from mean high tide to six nautical miles offshore around each of the five islands. Channel Islands National Marine Sanctuary was granted a special protected status and includes numerous marine protected areas that limit human activities.
Because protection of natural resources is one of the primary goals of CINMS, we are working on a project with CINMS to understand the impact of noise produced by commercial ships on the local ecosystem. Given the Sanctuary’s variety of ecologically important and sensitive habitats and significant populations of marine mammals including blue and humpback whales, large vessel traffic is an ongoing management concern for the CINMS. The shipping lanes of the Santa Barbara Channel overlap the eastern portion of the CINMS, with at least 6,500 vessels passing through the Sanctuary annually. In September 2004, the NOAA appointed Sanctuary Advisory Council unanimously adopted a set of recommendations put forth by their Conservation Working Group on how to address potential marine life impacts from anthropogenic noise sources. The Working Group’s report calls for CINMS to take progressive steps to promote greater scientific understanding of the issue and to investigate policy-based options for mitigating noise impacts. These recommendations have been incorporated into the 2006 CINMS Draft Management Plan.
Review of the evidence suggests that noise pollution is an important factor in the health of marine mammals. Behavioral data on marine mammal reaction to noise is complex; however, evidence suggests that when given the opportunity, marine mammals will avoid high-noise regions. High levels of noise may interfere with marine mammals’ ability to detect sounds such as calls of conspecifics, echos from prey, and natural sounds that aid in navigation or foraging. Noise may affect reproductive or immune functions and cause more generalized stress.
The first objective is to understand the acoustic environment in the sanctuary, including identification of different acoustic regions and propagation patterns. Techniques to achieve this goal include strategic placement of HARPs (high-frequency acoustic recording packages) in the region. These data will be processed and analyzed for characteristics of the ambient noise field, including the spectral, seasonal and diurnal patterns, as well as the characteristics of biological sources. By using several HARPs, different regions within the CINMS can be classified based on the level of anthropogenic noise and biological sources (marine mammals and fish). Models of propagation will be created based on water properties, bathymetry, and acoustic propagation from known sound sources (e.g. commercial vessels).
The second objective of this project is to identify the pervasive sources of anthropogenic noise in the CINMS region. Acoustic data from the HARPs will be combined with tracking data on commercial ships passing through the sanctuary using the AIS (automatic identification system). Marine regulations require AIS to be fitted aboard all ships of 300 gross tonnage or more engaged in international voyages, cargo ships of 500 gross tonnage or more engaged in domestic voyages, and all passenger ships irrespective of size. The AIS system provides information on the vessel characteristics (e.g. dimensions, type) as well as instantaneous operating parameters (e.g. location, speed, heading). Towed array acoustic recordings from the R/V Shearwater will ground truth and supplement the information derived from the HARPs and AIS. The significant number of vessels passing through the CINMS area provides a unique opportunity to characterize noise levels from a broad range of commercial vessels.
The third objective is to evaluate the potential impact of noise on marine animals in the region on individual and population level. Marine mammals in the region will be monitored using acoustic data (HARPs and towed array), ship based observations, and using non-invasive tags to document behavioral patterns in the presence and absence of acoustic disturbances. Fish populations will be monitored using acoustic data and ancillary observations, comparing areas of high noise to areas of lower noise.
This project is in collaboration with the Channel Islands National Marine Sanctuary (CINMS). We bring to the collaboration the acoustics expertise of Dr. John Hildebrand, and the efforts of dedicated graduate student Megan McKenna. The CINMS has access to existing databases of cetacean distribution and fish pawning/distribution providing a baseline for current observations. Use of sanctuary vessels (R/V Shearwater) will allows us to tow hydrophone arrays, deploy acoustic instruments (HARPs and tags), make behavioral observations, document species-specific responses, and monitor ship traffic. We are currently expanding our acoustic monitoring of the region by deploying additional HARPs in addition to one in the Santa Barbara Channel and one off Pt. Conception. We have also installed two recording systems for the AIS ship tracking data to monitor within the sanctuary waters and allow the integration of the ship information with the acoustic data.