Working Group on Marine Habitat Mapping (WGMHM)
The Working Group on Marine Habitat Mapping (WGMHM) coordinates the review of habitat classification and mapping activities in the ICES area and promotes the standardization of approaches and techniques.
For the second consecutive year, WGMHM have held a joint meeting with the Working Group on Deep-Water Ecology (WGDEC) with a shared term of reference. The specific request to WGMHM in 2020 was to provide maps of VME elements in the North Atlantic. VME elements are defined as geomorphological features that provide habitat for VMEs. In addition, WGMHM undertook a series of examinations of each element to understand the strength of association between VME elements and specific VME habitats. The results of this analysis highlighted the following issues with the use of VME elements:
1) Elements are also listed without clear rule-sets for their consistent identification and de-lineation (i.e. a specification that states the acceptable input data sets, working resolu-tion, underlying data quality, exact method to produce terrain derivatives and the thresholds for delineating features).
2) The strength of association between specific elements and individual VME habitats is often poor.
3) Where the strength of association is high, the footprint of the VME element is excessively large (as either a small number of large units or numerous small units) and unlikely to be useful for the fine-scale delineation of spatial advice.
To make VME elements more useful for the provision of management advice, further work must be undertaken to refine the physical conditions captured by each element. This can be done by either narrowing the definitions of VME elements or by including more physico-chemical pa-rameters. However, this progression fundamentally represents an ad-hoc approach to what Pre-dictive Habitat Models (PHMs, also known as Habitat Suitability Models) do in an objective, efficient and sophisticated way. It is recommended that PHMs remain the primary method for investigating where VME habitats are likely to occur in areas lacking VME observations.
Published under the auspices of the following ICES Steering Group or Committee