Science Advisory Report 2022/045

An Assessment To Support Decisions on Authorizing Scientific Surveys with Bottom-Contacting Gears in Protected Areas in The Newfoundland and Labrador Bioregion

Summary

• Bottom-contacting fishing gears have impacts on benthic populations, communities, and habitats. These include direct impacts by damaging and removing organisms, and indirect impacts resulting from lost ecosystem services provided by these organisms and the biodiversity they may support.
• It is recognized that bottom-contacting scientific surveys have impacts on corals, sponges, and other benthic fauna. The level and nature of these impacts are taxon and gear dependent, however the first pass of bottom-contacting gear results in the greatest removal of and damage to specimens and biogenic features. The extent of these localized impacts on biodiversity and ecosystem function are not known.
• The recovery time for individual corals and sponges is expected to range between decades and centuries in the NL Region. While bottom-contacting survey gear can cause localized damage, the average recurrence time of scientific surveys in protected areas is orders of magnitude higher (~up to tens of thousands of years) than estimated recovery times. This suggests that individual corals and sponges would be expected to have sufficient time to recover between survey bottom contact events. The habitats they create (e.g., sponge grounds or gorgonian coral forests) would have much longer recovery times (possibly thousands of years). In comparison, the recurrence time for bottom-contacting commercial fishing gear in the NL Region is, on average, 10 years.
• The cumulative percentage of area impacted per year by bottom-contacting surveys was found to be less than 0.04% for each of the protected areas considered in the analysis.
• Retrospective analyses examined the effect of completely excluding bottom-contacting scientific survey data from protected areas on various time series data regularly used in the provision of science advice. These analyses illustrated that the exclusion of surveys in protected areas would be likely to introduce bias in some time series data, and would, in some cases, hinder the ability to provide reliable science advice on a broad range of topics (e.g., on stock assessments, ecosystem assessments, climate studies, long-term monitoring).
• Shifts in species distributions and trends are expected in association with directional changes in the environment (e.g., climate change), therefore, excluding sets from protected areas may hinder the ability to reliably track future ecological and environmental changes.
• Avoiding protected areas with benthic conservation objectives is the only way to completely eliminate the impact of bottom-contacting gears on these features. However, given that (1) survey recurrence times are high and the proportion of protected areas impacted is low, (2) excluding surveys from these areas will hinder ecosystem monitoring and, (3) from a multispecies perspective, there is currently no suitable alternative to bottom trawl surveys, a blanket exclusion of research surveys from all protected areas is not recommended at this time. If excluding research survey sets from protected areas with benthic conservation objectives is not an option, it is recommended that methods to minimize the potential impacts of these surveys be fully explored. Potential proactive mitigation measures can include: (1) the reduction of sampling intensity within closures, (2) the identification of zones for research trawls within closures to avoid locations with known high densities of corals or sponges, and (3) the offsetting of survey impacts by expanding closed areas.
• DFO should develop a framework to assist in the selection and implementation of appropriate mitigation measures for protected areas with benthic conservation objectives.
• An important associated measure is the development of enhanced sampling protocols to maximize the information gathered relating to benthic conservation objectives in protected areas.
• The establishment and delineation of protected areas has relied in part on data from bottom-contacting scientific surveys. Going forward, it may be possible to monitor fish and shellfish communities within protected areas with bottom-contacting surveys, but these are not the most appropriate methods to undertake long-term monitoring of vulnerable benthic taxa. For these taxa, alternative, less-destructive methods like seafloor visual surveys (e.g., remotely operated vehicles [ROVs], drop cameras) are more appropriate. Yet, the removal of bottom-contacting surveys would hinder the provision of advice relating to some conservation objectives.

This Science Advisory Report is from the Regional Peer Review process of October 5–9, 2020 on An Assessment to Support Decisions on Authorizing Scientific Surveys With Bottom-Contacting Gears In Protected Areas In The Newfoundland And Labrador Bioregion. Additional publications from this meeting will be posted on the Fisheries and Oceans Canada (DFO) Science Advisory Schedule as they become available.

Science Advisory Report 2022/045 (PDF, 3,242 KB)

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