Targets and goals to mitigate the potentially negative consequences of anthropogenic pressures on marine ecosystems are proposed by international policy frameworks, such as the Convention on Biological Diversity (CBD), and the United Nations Sustainable Development Goals. Almost all nations have agreed on these targets and goals. Among those, Mexico, as a signatory member of the CBD and the Convention on Fishing and Conservation of Living Resources of the High Seas of 1958, has committed to protecting and improving conservation efforts for marine biodiversity. In fact, large portions (22.05%) of its Exclusive Economic Zone (EEZ) are designated as marine protected areas (MPAs).
But are those MPAs effective for pelagic seabirds?
Lack of knowledge on seabirds’ at-sea distribution in the Mexican seas prevented this important information being incorporated in MPA planning. Seabirds’ at-sea distribution is strongly affected by climate, including El Niño Southern Oscillation, and also determined by the alternate need to forage in areas relatively close to the colonies during the breeding season, and the possibility to roam the wide ocean on erratic movement during the non-breeding period. Physical factors, such as ocean currents and wind streams, may enhance or limit ocean productivity and thus the energetic budgets of seabirds.
Black-vented Shearwater by Joel Aaron Lopez Hernandez
Tracking the Black-vented shearwater in the Mexican Pacific for 4 years allowed us to identify the multi-dimensional space used by this endemic Near Threatened species. These areas might be different in times of scarcity, like during El Niño events, or during more favourable seasons. BirdLife International’s method for marine KBA identification allowed us to determine the areas of more frequent general use, which did not entirely coincide with the main foraging areas. The colony in Natividad Island placed between the Baja California Peninsula and the windier regions of the open seas, in the southern part of the California Current System stream. This location makes it obvious to have a binary choice for shearwaters when heading out at sea: North or South?
We looked for behavioural consistency across years and in the use of foraging areas detected by behavioural classification of tracks’ sections and confirmed by diving information. This information across four years was pooled with the global standard used to identify important sites for biodiversity – the Key Biodiversity Area standard – to determine the core use areas for foraging and rafting.
Figure 4 from Soldatini et al. 2022: Map of broad foraging areas (75% contour; light orange) and core foraging areas (25% contour; dark orange).
The areas obtained are only partially included in the MPAs, calling for a revision of MPAs limits and of their management plans to protect the areas used by Black-vented Shearwater during their breeding season from February to July. This is the first time such an approach is applied in Mexico, and we hope it will be the first of many steps toward a more effective protection of seabirds in Mexican EEZ.
Cecilia Soldatini’s research interests focus on seabirds as environmental indicators in marine ecosystems, including foraging and diet, behavioural ecology, regulation of trade-offs in response to variable environmental conditions. You can find out more about the Aeroecología Marina research group on their website, Facebook and Twitter.