Biologically Important Areas
The Biologically Important Areas (BIAs) component of the CetMap effort supplements the quantitative information on cetacean density, distribution, and occurrence by: 1) identifying areas where cetacean species or populations are known to concentrate for specific behaviors, or be range-limited, but for which there is not sufficient data for their importance to be reflected in the quantitative mapping effort; and 2) providing additional context within which to examine potential interactions between cetaceans and human activities. This information can assist resource managers with planning, analyses, and decisions regarding how to reduce adverse impacts to cetaceans resulting from human activities.
Specific to anthropogenic sound and marine mammals, Ellison et al. (2012) summarize compelling evidence indicating that a variety of contextual factors, including behavioral state, can determine the probability, nature, and extent of a marine mammal's response to sound. Ellison et al. (2012) further suggest that the scientific community believes that the federal agencies responsible for producing and regulating sound should incorporate context into their behavioral-response assessments. The BIAs are intended to identify some of this important contextual, behavioral state information for cetaceans and augment impact assessments that have previously been based solely on the received level of sound.
Definition of Biologically Important Area
For this exercise, regional experts were asked to compile the best available information from scientific literature (including books, peer-reviewed articles, and government or contract reports), unpublished data (sighting, acoustic, tagging, genetic, photo identification), and expert knowledge to create written summaries and maps highlighting areas shoreward of the U.S. Exclusive Economic Zone (EEZ) that are biologically important to cetacean species (or populations), either seasonally or year-round.
For cetacean species with distinct migrations that separate feeding and breeding areas, three types of biologically important areas were identified:
- Reproductive Areas: Areas and months within which a particular species or population selectively mates, gives birth, or is found with neonates or other sensitive age classes.
- Feeding Areas: Areas and months within which a particular species or population selectively feeds. These may either be found consistently in space and time, or may be associated with ephemeral features that are less predictable but can be delineated and are generally located within a larger identifiable area.
- Migratory Corridors: Areas and months within which a substantial portion of a species or population is known to migrate; the corridor is typically delimited on one or both sides by land or ice.
A fourth type of biologically important area was also identified:
- Small and Resident Population: Areas and months within which small and resident populations occupying a limited geographic extent exist.
As described above, the purpose of identifying these areas is to help resource managers with planning and analysis through the augmentation of existing spatial tools. For that reason, certain criteria were included in the definitions of the BIAs to increase their utility. Specifically, we restrict the fourth type of BIA to “small and resident” populations “occupying a limited geographic extent” because NOAA’s stock assessment reports already cite the range and abundance of all US marine mammal species or populations, including small or resident populations whose range is either unknown or relatively large. While CetMap does not explicitly define “small,” we highlight populations whose ranges span only a bay, an area around one island, or a portion of what CetMap defines as a region. Additionally, areas that have been officially designated by NOAA as “critical habitat” were included in part or in their entirety if they meet the definition of BIAs. The decision to not designate a critical habitat area as a BIA should not be interpreted as undermining the value of the critical habitat area; rather, the development of critical habitat considers a complex combination of factors that do not always match the simple definitions of BIAs, and therefore not everything identified as critical habitat will meet the BIA criteria, and vice versa. In the few instances where small or resident populations have been identified that we determined occupied too large of a range to delineate as a BIA, or a designated critical habitat area exists that does not meet the definition of a BIA, we have still included text in the narrative highlighting the population or area and the rationale for not designating a BIA.
Ellison, W. T., B.L. Southall, C.W. Clark, and A. Frankel. 2012. A new context-based paradigm to assess behavioral responses of marine mammals to sound. Con. Bio. 26:21-28.
Information Presented for Each Important Area
For each region and species or population with known areas of biological importance, information is presented in a written summary with an associated map and metadata table. The metadata table details the type and quantity of information used to define the Important Area, providing a transparent method for evaluating the Important Area designation.
The following caveats should be kept in mind when using Important Areas in environmental assessments or impact analyses:
- Areas outside of the US EEZ were not evaluated as part of the BIA exercise; however, available information for outlying areas was considered when determining whether areas within the US EEZ should be considered biologically important. Therefore, absence of BIA designations outside of the US EEZ should NOT be interpreted to mean absence of BIAs in those outlying waters.
- Only known areas and periods of biological importance were identified; other areas that are biologically important to cetaceans could exist within the U.S. EEZ but not be included here due to insufficient information.
- The quantity and type of data from within the U.S. EEZ used to define the Important Areas were spatially and temporally heterogeneous. The types of data used included sighting, acoustic, tagging, genetic, and photo identification data.
- The Important Area summaries and metadata tables should be consulted to determine which regions and periods were considered, what data support the designations, and where and when information is lacking.
- The Important Area designation is not equivalent to habitat or range. For distinctly migratory species or populations, Important Areas highlight specific locations and periods within which critical behaviors occur and likely represent only a fraction of the overall range. In contrast, an Important Area designation encompasses the entire known range of small or resident cetacean populations within an indicated period, but does not identify habitat structure within the Important Area.
The Important Area documents have undergone a two-step review process by scientists with expertise in particular species and regions to ensure that the information presented is accurate, based on the best available knowledge, presented consistently across regions, and supported by the references cited and metadata tables. The first review was undertaken by members of the CetMap Working Group, and the second review was undertaken by scientists at each of NOAA’s Fisheries Science Centers. The CetMap Working Group is also undertaking external review of the documents by subject matter experts outside NOAA and is preparing a collection of manuscripts focused on the Important Areas that will be submitted to a scientific journal for external peer-review by subject matter experts. The first manuscript in the collection will detail the methods used to identify the Important Areas and discuss the strengths and limitations of the Important Area identification process and associated products; subsequent manuscripts will present each region’s Important Area documents in their entirety.