Summary of current IMMAs

As of February 2024, 280 IMMAs have been identified following the hosting of ten expert workshops in the regions represented in Table 1 below. There are an additional 185 Areas of Interest (AoI). Details of all these are in the searchable database and 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 Workshop

IMMA size

There is a huge range in size among different IMMAs, the largest is 4,014,498 km2 encompassing an area Southwest Atlantic humpback whale migratory corridor in the South West Atlantic Ocean, and the smallest is 1 km2, the São Pedro and São Paulo Archipelago IMMA  which hosts a very small population of common bottlenose dolphins (Tursiops truncatus).

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 242 IMMAs identified as of September 2023 (note that one IMMA can meet multiple criteria, so the totals in the table are greater than 209).

Figure 1 shows the number of IMMAs broken down by the sub-criterion applied.  After Criterion A (Species or Population Vulnerability (22%), the most frequently used sub-criteria were C1 (Reproductive Areas) (17%) and C2 (Feeding Areas) (16%).

Figure 1 – Number of IMMAs broken by subcriteria

Qualifying Species in each IMMA

The documentation for each IMMA includes a list of the qualifying marine mammal species that occur and that are fundamental to satisfying each criterion used in the IMMA identification.  Supporting 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 qualifying species listed for each IMMA.  The majority were identified on the basis of one or two qualifying species.

Seventy-nine different marine mammal species have been used as the qualifying species for an IMMA.  As shown on Figure 3, humpback whales (Megaptera novaeangliae), dugongs (Dugon dugon), blue whale (Balaenoptera musculus), common bottlenose dolphins (Tursiops truncatus), Sperm whales (Physeter macrocephalus) and spinner dolphins (Stenella longirostris) were the most commonly represented species.

Figure 2 – Number of qualifying marine mammal species listed for each IMMA

Figure 3 – Qualifying marine mammal species used to satisfy the IMMA criteria