As of January 2020, 114 IMMAs have been identified following the hosting of five expert workshops in the regions represented in Table 1 below. There are an additional 22 candidate IMMAs (cIMMAs) and 110 Areas of Interest (AoI). Details of all these are on the searchable database (in progress) and are displayed on the e-Atlas. Table 1 shows the number of IMMAs by region.
Table 1 - Summary of the number of IMMAs, cIMMAs and AoI by Region
North East Atlantic
North East Indian Ocean and South East Asian Seas
Western Indian Ocean and Arabian Seas
The total area of all 114 IMMAs combined is 4,072,536 km2. There is a huge range in size among different IMMAs, the largest is 431,498 km2 encompassing an area of the Pacific Ocean around the Cook Islands Southern Group in the Pacific Islands, and the smallest is 45 km2, the Akrotiri IMMA which includes small breeding caves for the Mediterranean monk seal (Monachus monachus). 51% (58) of IMMAs are less than 10,000 km2 in size; only 13 IMMAs (13%) have an area greater than 100,000 km2.
Criteria used to identify IMMAs
Table 2 provides a summary of the criteria that have been used to identify IMMAs: Criteria C, Key Life Cycle Attributes, which includes migration routes, reproductive areas and feeding areas has been the most frequently used criterion, and Criterion D, Special Attributes has been the least frequently used.
Table 2 - Summary of the criteria used to identify the 114 IMMAs identified as of January 2020 (note that one IMMA can meet multiple criteria, so the totals in the table are greater than 114).
Species or Population Vulnerability
Distribution or Abundance
Key Life Cycle Attribute
Figure 1 shows the number of IMMAs broken down by the sub-criterion applied. After Criterion A (Species or Population Vulnerability (25%), the most frequently used sub-criteria were Bi (Small Resident Populations) (13%), Bii (Aggregations) (15%) and Ci (Reproductive Areas) (18%).
The documentation for each IMMA includes a list of the primary marine mammal species that occur and that are fundamental to satisfying each criterion used in the IMMA identification. Secondary species are marine mammal species that occur within the IMMA but which are not fundamental to satisfying the criteria. Figure 2 shows the number of primary species listed for each IMMA. The majority were identified on the basis of one or two primary species.
Thirty-nine different marine mammal species have been used as the primary species for an IMMA. As shown on Figure 3, humpback whales (Megaptera novaeangliae), spinner dolphins (Stenella longirostris) and dugongs (Dugon dugon) were the most commonly represented species.
Figure 2 – Number of primary marine mammal species listed for each IMMA (* the IMMA with 0 primary species was identified based on the diversity criterion Dii)
Figure 3 – Primary marine mammal species used to satisfy the IMMA criteria (only species listed as primary species more than 4 times are shown)