The intent of UNGA Resolution 61/105 and the SPRFMO Interim Measures is to prevent significant adverse impacts on fragile benthic species in deep water. Concerns are mainly focused on the impact of mobile fishing gears that are designed to, or are likely to, move across the seabed during fishing, causing direct physical impacts to structure-forming benthic species. Bottom fishing is defined as fishing with any gear type likely to come in contact with the bottom (FAO 2008). The SPRFMO intermediate measures apply to all bottom fishing methods (SPRFMO 2007a). While some benthic ecosystems are more vulnerable to disturbance than others, they are also differentially vulnerable to the impacts of different bottom fishing gears.
Gear type and how the gear is to be fished is an important component of the evaluation of any fishing plan. Gear impact should be evaluated as a product of the typical seabed impact footprint per set or tow of the gear type to be used, the planned number of fishing events (to provide an estimate of the overall extent of physical impact), the likelihood of encountering vulnerable species in proposed fishing areas (including the proportion of planned deployments occurring in new areas) and the expected degree of impact by the gear type concerned, to generate an index of potential disturbance. Default rankings of expected level of impact by gear type are provided in Table 2.
Table 2. Ratings of habitat impact for each gear class on a scale of 1 (very low) to 5 (very high) (from Chuenpagdee et al. 2003).
By using a characterisation instead of a definition, the FAO deep-sea guidelines avoid discussing region-specific details of taxonomic level, organism abundance or local biodiversity as potential criteria to use in assessments, or for triggering management actions. In order to implement the SPRFMO Interim Measures for Bottom Fisheries (SPRFMO 2007a), details of actual species or higher level taxa known or likely to contribute to VMEs in the South Pacific deep-seas, and the catching of which could indicate evidence of such VMEs, need to be established. The relevant SPRFMO interim measures state:
Bottom fisheries: In respect of bottom fisheries, Participants resolve to:
6. In respect of areas where vulnerable marine ecosystems are known to occur or are likely to occur based on the best available scientific information, close such areas to bottom fishing unless, based on an assessment undertaken in accordance with paragraphs 11 and 12 below, conservation and management measures have been established to prevent significant adverse impacts on vulnerable marine ecosystems and the long-term sustainability of deep sea fish stocks or it has been determined that such bottom fishing will not have significant adverse impacts on vulnerable marine ecosystems or the long term sustainability of deep sea fish stocks.
7. Require that vessels flying their flag cease bottom fishing activities within five (5) nautical miles of any site in the Area where, in the course of fishing operations, evidence of vulnerable marine ecosystems is encountered, and report the encounter, including the location, and the type of ecosystem in question, to the interim Secretariat so that appropriate measures can be adopted in respect of the relevant site. Such sites will then be treated in accordance with paragraph 6 above.
Implementation of these measures requires specific definitions of:
Evidence of a VME to trigger the move-on provisions of interim measure 7; and
Existence of areas known or likely to contain VMEs, to trigger the management requirements of interim measure 6.
It is important to distinguish between these. A protocol to determine ‘Evidence of a VME’ is required to enable a rapid assessment and immediate management response during actual fishing operations at sea, to limit immediate impact on areas which appear to support significant quantities of VME species. In contrast, ‘Designating a VME’ requires a scientific and deliberative longer-term analysis to integrate data from individual encounters and assess information on occurrence of VMEs across larger spatial scales, in order to identify, map and designate areas which are considered to constitute actual VMEs.