VELMU Survey Methods

VELMU has collected data from over 160 000 points since 2004. This has given a general overview of species and habitats distribution in the Finnish marine areas. The various methods deployed are described below. 

VELMU aaltoviiva


Geological survey methods

Geological surveys are mainly conducted using acoustic methods, particularly multibeam echo sounding.

Geological survey methods. Image: H. Kutvonen GTK


Diving and bottom sampling

Diving allows for direct observation of species and habitats and sampling of hard-bottom fauna. For sampling of soft-bottom fauna, grab samplers are operated on board small boats or research vessels.

Sampling with van Veen sampler. Photo: SYKE

Video methods

Most of the observations under VELMU are carried out using video photography methods. With video photography, data on species and habitats can be collected in a timely fashion and cost efficiently. Both drop video cameras and remotely operated vehicles (ROV) are used.


A drop video camera. Photo: Tiina Asp, Metsähallitus.



Researcher steering a remotely operated vehicle equipped with a camera. Photo: SYKE


Saduria entomon captured in an ROV image from the Eastern Gulf of Finland. Photo: Anna Downie SYKE.


Methods for surveying fish breeding grounds

Under VELMU, data on fish spawning and larval areas in coastal regions are also collected. The collection methods used include, among others, scooping, white plate, Gulf-Olympia sampler and remote sensing.

Sampling with a white plate. Photo: Meri Kallasvuo, Luke.



Because it is not possible to monitor all sea areas, species and communities distribution models are developed based on species observations and environmental factors. Models are developed for vascular plants, macroalgae, benthos and fish species. Maps produced from data generated by models can be used, for instance, for comparison purposes and in planning.

Probability of occurence of Claspingleaf pondweed (Potamogeton perfoliatus) in Hanko peninsula (2011).
Image: Minna Ronkainen SYKE


Published 2020-12-29 at 18:08, updated 2022-03-07 at 11:50