Evaluation of the full set of habitat suitability models for vulnerable marine ecosystem indicator taxa in the South Pacific high seas

\ua9 2024 The Authors. Fisheries Management and Ecology published by John Wiley & Sons Ltd. In the high seas, regional fishery management organisations are required to implement measures to prevent significant adverse impacts on vulnerable marine ecosystems (VMEs). Our objectives were to develop habitat suitability models for use in the spatial management of bottom fisheries in the South Pacific and to evaluate these and existing models using independent data from high-quality seafloor imagery. Presence-only models for seven VME indictor taxa were developed to complement previous modelling. Evaluation of habitat suitability models using withheld data indicated high mean True Skill Statistic scores of 0.44–0.64. Most habitat suitability models performed adequately when assessed with independent data on taxon presence and absence but were poor surrogates for abundance. We therefore advocate caution when using presence-only models for spatial management and call for more systematically collected data to develop abundance models

Independent statistical validation of the New Zealand Seafloor Community Classification

\ua9 2024 The Authors. Aquatic Conservation: Marine and Freshwater Ecosystems published by John Wiley & Sons Ltd. The New Zealand Seafloor Community Classification (NZSCC) is a national-scale numerical community classification which depicts compositional turnover of 1716 taxa (demersal fish, reef fish, benthic invertebrates and macroalgae) classified into 75 groups representing seafloor communities. To ensure the continual use of the NZSCC for spatial planning and reporting, a robust maintenance framework must be set in place; key to this is being able to assess the ability of the classification to represent (discriminate between) different seafloor communities. Here we describe an approach for validating the NZSCC using temporally independent evaluation data for demersal fish and benthic invertebrates (the latter sampled via a different method), which identifies whether the NZSCC represents different seafloor communities (i.e., assesses classification strength), evaluates the underlying statistical model, and considers heterogeneity in environmental coverage and statistical uncertainty. Additionally, the availability of abundance estimates for these evaluation datasets provides an opportunity to test whether the NZSCC—which was developed using presence-absence data—can reflect abundance-weighted seafloor communities. The ANOSIM global R values (measuring classification strength) were 0.53 and 0.46 (and significant at the 1% level) for demersal fish and benthic invertebrates, respectively, indicating that the NZSCC groups define biologically distinctive environments. The proportion of significant inter-group differences were very high (95% and 97% for demersal fish and benthic invertebrates, respectively) suggesting NZSCC groups were distinct from each other in their taxonomic composition. There were positive relationships between the evaluation datasets and the underlying statistical model. There was no evidence of these relationships being affected by the statistical uncertainty of the NZSCC. NZSCC model validation metrics using abundance evaluation data were also moderately high (albeit lower than for presence-absence for invertebrates) suggesting that the NZSCC, can at least in part, represent variation in abundance-weighted communities. Results presented here suggest that the existing NZSCC is currently fit-for-purpose for informing management decisions

Bottom-trawling affects the viability of climate refugia for vulnerable marine ecosystem indicator taxa

\ua9 2025 The Author(s)Bottom trawling significantly impacts benthic ecosystems, including deep-sea habitats. International guidelines recognize Vulnerable Marine Ecosystems (VMEs) as ecologically critical ecosystems at risk from fishing. In New Zealand, spatial protection measures aim to mitigate some effects of bottom trawling but remain insufficient to preserve essential habitats of VME indicator taxa under current and future climatic conditions. Using the dynamic Relative Benthic Status (dRBS) approach and density predictions for 10 VME indicator taxa, we evaluated the historical impacts of bottom trawling across New Zealand\u27s seas, focusing on primary habitats and climate refugia predicted under future scenarios (SSP2-4.5, SSP3-7.0). Our results show that bottom trawling is expected to have impacted all assessed taxa across the study region, albeit with different intensities. Areas identified as climate refugia were particularly affected, showing the greatest reductions in both taxon density and habitat extent. Overall density losses were similar among taxa within internal climate refugia (i.e., current high-density areas predicted to maintain high densities in the future) at approximately 7–8 % and external refugia (i.e., new areas where certain taxa were predicted to expand into in the future) at approximately 9–10 % under both climate scenarios. Nevertheless, the predicted reduction in current-day density was higher in internal refugia (on average 4000 individuals per km2) compared to external refugia (on average 500 individuals per km2). Habitat extent reductions were also greater in internal refugia (∼10 %) than in external refugia (∼4 %). Identifying and protecting climate refugia must be a conservation priority, as they represent areas where taxa may persist or expand under future climates. Careful consideration of these areas is required to reduce extinction risk and ensure the long-term conservation of ecosystem services

Identifying climate refugia for vulnerable marine ecosystem indicator taxa under future climate change scenarios

\ua9 2024 The Authors. Vulnerable Marine Ecosystems (VMEs) are recognised as having high ecological significance and susceptibility to disturbances, including climate change. One approach to providing information on the location and biological composition of these ecosystems, especially in difficult-to-reach environments such as the deep sea, is to generate spatial predictions for VME indicator taxa. In this study, the Random Forest algorithm was used to model the spatial distribution of density for 14 deep-water VME indicator taxa under current environmental conditions and future climate change scenarios (SSP2-4.5 and SSP3-7.0) within the New Zealand Territorial Sea and Exclusive Economic Zone (100–1500 m water depth) to evaluate potential changes in the location and distribution of density of these taxa over time. Overall, our species distribution models performed well for all taxa (mean AUC = 0.82; TSS = 0.56; r = 0.40) and predicted a considerable average reduction in density (54%) and habitat extent (61%), by the end of the 21st century under both climate change scenarios. Nevertheless, models identified regions that might serve as internal refugia (approximately 158,000 km2), where some taxa are predicted to maintain the high densities predicted for current-day environmental conditions under future climatic conditions, and external refugia (approximately 121,000 km2) where taxa were predicted to expand into new locations by the end of the 21st century. Our results represent a significant step forward as they provide predictions of the distribution of taxa densities, rather than just occurrence, under both present and future climatic conditions. Furthermore, these findings carry implications for ecosystem management and spatial planning, suggesting current marine spatial protection measures may not offer adequate protection to VME indicator taxa in the face of climate change. Additionally, activities like bottom trawling, present or future, may jeopardize climate refugia viability. Thus, a comprehensive assessment of cumulative effects on VME indicator taxa is recommended to establish effective protection measures for potential climate refugia, ensuring the continuity of essential ecosystem services

Large-scale assessments of bottom trawling effects on Vulnerable Marine Ecosystems can significantly under-represent impacts

\ua9 2025 The Author(s). Bottom trawling threatens Vulnerable Marine Ecosystems (VMEs). We evaluated historic benthic trawling impacts on 10 VME indicator taxa (e.g. cold-water corals) and estimates of VME distribution (based on the overlap of taxa abundance-based and richness-based indices) across New Zealand waters, using a dynamic Relative Benthic Status model, incorporating 30 years of fishing data, and taxon-specific depletion and recovery rates. The analysis was conducted at a national scale and within six ecologically relevant bioregional scales. We predicted severe, lasting impacts at bioregional levels, despite modest national-scale effects. All VME indicator taxa fell below an 80% \u27good ecosystem state\u27 threshold in at least one bioregion, with VMEs in three of six bioregions below this critical limit. Combined with limited observed recovery for these taxa 20–40 years post-fishing, these impacts likely represent Significant Adverse Impacts. By integrating high-resolution spatial predictions with long-term impact assessments at ecologically relevant scales, our approach provides a novel replicable framework for regional and global assessments, identifying pristine areas vital for conservation under agreements like the High Seas Treaty. This study is an important step towards sustainable fisheries management and marine biodiversity conservation, providing essential insights to guide policy decisions and protect the oceans\u27 most vulnerable ecosystems from bottom trawling

The right tools for the job: Considerations for the implementation of an ecosystem-based management approach for marine ecosystems

\ua9 The Author(s) 2025. Ecosystem-based management (EBM) is vital for sustainably managing marine ecosystems. A range of decision-making tools have been developed to support EBM, but marine EBM implementation globally remains slow. We provide a framework for tool selection and integration into EBM. Drawing on two cases involving researcher and end-user engagement, we identify nine key lessons to improve tool adoption for EBM with the aim of enhancing marine management and ecosystem protection

Optimal siting, sizing, and enforcement of marine protected areas

The design of protected areas, whether marine or terrestrial, rarely considers how people respond to the imposition of no-take sites with complete or incomplete enforcement. Consequently, these protected areas may fail to achieve their intended goal. We present and solve a spatial bio-economic model in which a manager chooses the optimal location, size, and enforcement level of a marine protected area (MPA). This manager acts as a Stackelberg leader, and her choices consider villagers’ best response to the MPA in a spatial Nash equilibrium of fishing site and effort decisions. Relevant to lower income country settings but general to other settings, we incorporate limited enforcement budgets, distance costs of traveling to fishing sites, and labor allocation to onshore wage opportunities. The optimal MPA varies markedly across alternative manager goals and budget sizes, but always induce changes in villagers’ decisions as a function of distance, dispersal, and wage. We consider MPA managers with ecological conservation goals and with economic goals, and identify the shortcomings of several common manager decision rules, including those focused on: (1) fishery outcomes rather than broader economic goals, (2) fish stocks at MPA sites rather than across the full marinescape, (3) absolute levels rather than additional values, and (4) costless enforcement. Our results demonstrate that such naïve or overly narrow decision rules can lead to inefficient MPA designs that miss economic and conservation opportunities