The object of monitoring is to obtain a measure of the health of a population, ecosystem or the impact of an action such as protection. In the case of marine mammals, monitoring frequency should allow a representative measure of abundance or habitat usage. Monitoring frequency depends on factors including the goal of the monitoring programme and the availability of resources. It also depends on whether a species is migratory, sedentary, or uses local different local habitats throughout the year.
Resident marine mammal species often reside in the one area, but many species show a variety of movement behaviours at a location. For example, around Tenerife, in the Canary Islands, some short-finned pilot whales are resident, some undergo small-scale migrations, and some are thought to be transient . Therefore, the monitoring frequency should reflect the goal of the monitoring. If the purpose of the monitoring is to generate an absolute or relative census, then once per year or every two years may be sufficient. However, where monitoring relates to, for example, habitat use over time, or developing an understanding of subpopulations, multiple surveys may be required each year.
 Noad, M.J., Dunlop, R.A., Paton, D. and Cato, D.H. 2008. Unpublished report, An update of the east Australian humpback whale population (E1) rate of increase, International Whaling Commission Scientific Committee, Santiago, Chile.
 Dawson S., Wade P., Slooten E. and Barlow J. 2008. Design and field methods for sighting surveys of cetaceans in coastal and riverine habitats. Mammal Review 38 (1): 19–49
 Servidio A, Pérez-Gil E, Pérez-Gil M,Cañadas A, Hammond PS, Martín V. Site fidelity and move-ment patterns of short-finned pilot whales within the CanaryIslands: Evidence for resident and transient populations.Aquatic Conserv: Mar Freshw Ecosyst. 2019;29(S1):227–241.
 Pomeroy R.S., Parks J.E., Watson L.M. 2004. How is your MPA doing? A guidebook of natural and social indicators for evaluating marine protected area management effectiveness. IUCN, Gland, Switzerland and Cambridge, UK. 234 pp