An MPA design approach to benefit fisheries: maximising larval export and minimising redundancy

In the design of marine protected areas (MPAs), tailoring reserve placement to facilitate larval export beyond reserve boundaries may support fished populations and fisheries through recruitment subsidies. Intuitively, capturing such connectivity could be purely based on optimising larval dispersal metrics such as export strength. However, this can lead to inefficient or redundant larval connectivity, as the subset of sites with the best connectivity metrics might share many of the same connections, making them, collectively, poor MPA candidates to provide recruitment subsidies to unprotected sites. We propose a simple, dynamic algorithm for reserve placement optimisation designed to select MPAs sequentially, maximising larval export to the overall network, whilst accounting for redundancy in supply from multiple sources. When applied to four regions in the Caribbean, the algorithm consistently outperformed approaches that did not consider supply redundancy, leading to, on average, 20% greater fished biomass in a simulated model. Improvements were most apparent in dense, strongly connected systems such as the Bahamas. Here, MPA placement without redundancy considerations produced fishery benefits worse than random MPA design. Our findings highlight the importance of considering redundancy in MPA design, and offer a novel, simple approach to improving MPA design for achieving fishery objectives

Ocean zoning within a sparing versus sharing framework

The land-sparing versus land-sharing debate centers around how different intensities of habitat use can be coordinated to satisfy competing demands for biodiversity persistence and food production in agricultural landscapes. We apply the broad concepts from this debate to the sea and propose it as a framework to inform marine zoning based on three possible management strategies, establishing: no-take marine reserves, regulated fishing zones, and unregulated open-access areas. We develop a general model that maximizes standing fish biomass, given a fixed management budget while maintaining a minimum harvest level. We find that when management budgets are small, sea-sparing is the optimal management strategy because for all parameters tested, reserves are more cost-effective at increasing standing biomass than traditional fisheries management. For larger budgets, the optimal strategy switches to sea-sharing because, at a certain point, further investing to grow the no-take marine reserves reduces catch below the minimum harvest constraint. Our intention is to illustrate how general rules of thumb derived from plausible, single-purpose models can help guide marine protected area policy under our novel sparing and sharing framework. This work is the beginning of a basic theory for optimal zoning allocations and should be considered complementary to the more specific spatial planning literature for marine reserve as nations expand their marine protected area estates

Artisanal fish fences pose broad and unexpected threats to the tropical coastal seascape

Gear restrictions are an important management tool in small-scale tropical fisheries, improving sustainability and building resilience to climate change. Yet to identify the management challenges and complete footprint of individual gears, a broader systems approach is required that integrates ecological, economic and social sciences. Here we apply this approach to artisanal fish fences, intensively used across three oceans, to identify a previously underrecognized gear requiring urgent management attention. A longitudinal case study shows increased effort matched with large declines in catch success and corresponding reef fish abundance. We find fish fences to disrupt vital ecological connectivity, exploit > 500 species with high juvenile removal, and directly damage seagrass ecosystems with cascading impacts on connected coral reefs and mangroves. As semi-permanent structures in otherwise open-access fisheries, they create social conflict by assuming unofficial and unregulated property rights, while their unique high-investment-low-effort nature removes traditional economic and social barriers to overfishing

Marine Reserve Targets to Sustain and Rebuild Unregulated Fisheries

Overfishing threatens the sustainability of coastal marine biodiversity, especially in tropical developing countries. To counter this problem, about 200 governments worldwide have committed to protecting 10%–20% of national coastal marine areas. However, associated impacts on fisheries productivity are unclear and could weaken the food security of hundreds of millions of people who depend on diverse and largely unregulated fishing activities. Here, we present a systematic theoretic analysis of the ability of reserves to rebuild fisheries under such complex conditions, and we identify maximum reserve coverages for biodiversity conservation that do not impair long-term fisheries productivity. Our analysis assumes that fishers have no viable alternative to fishing, such that total fishing effort remains constant (at best). We find that realistic reserve networks, which protect 10%–30% of fished habitats in 1–20 km wide reserves, should benefit the long-term productivity of almost any complex fishery. We discover a “rule of thumb” to safeguard against the long-term catch depletion of particular species: individual reserves should export 30% or more of locally produced larvae to adjacent fishing grounds. Specifically on coral reefs, where fishers tend to overexploit species whose dispersal distances as larvae exceed the home ranges of adults, decisions on the size of reserves needed to meet the 30% larval export rule are unlikely to compromise the protection of resident adults. Even achieving the modest Aichi Target 11 of 10% “effective protection” can then help rebuild depleted catch. However, strictly protecting 20%–30% of fished habitats is unlikely to diminish catch even if overfishing is not yet a problem while providing greater potential for biodiversity conservation and fishery rebuilding if overfishing is substantial. These findings are important because they suggest that doubling or tripling the only globally enforced marine reserve target will benefit biodiversity conservation and higher fisheries productivity where both are most urgently needed

Evaluating sustainable development policies in rural coastal economies

Sustainable development (SD) policies targeting marine economicsectors, designed to alleviate poverty and conserve marine ecosystems,have proliferated in recent years. Many developingcountries are providing poor fishing households with new fishingboats (fishing capital) that can be used further offshore as a meansto improve incomes and relieve fishing pressure on nearshore fishstocks. These kinds of policies are a marine variant of traditionalSD policies focused on agriculture. Here, we evaluate ex anteeconomic and environmental impacts of provisions of fishing andagricultural capital, with and without enforcement of fishingregulations that prohibit the use of larger vessels in nearshorehabitats. Combining methods from development economics, naturalresource economics, and marine ecology, we use a uniquedataset and modeling framework to account for linkages betweenhouseholds, business sectors, markets, and local fish stocks. Weshow that the policies investing capital in local marine fisheries oragricultural sectors achieve income gains for targeted households,but knock-on effects lead to increased harvest of nearshore fish,making them unlikely to achieve conservation objectives in ruralcoastal economies. However, pairing an agriculture stimulus withincreasing enforcement of existing fisheries’ regulations may leadto a win–win situation. While marine-based policies could be animportant tool to achieve two of the United Nations SustainableDevelopment Goals (alleviate poverty and protect vulnerable marineresources), their success is by no means assured and requiresconsideration of land and marine socioeconomic linkages inherentin rural economies

The inclusion of fisheries and tourism in marine protected areas to support conservation in Indonesia

With the rapid growth of Indonesia’s marine protected area (MPAs) estate in Indonesia, reaching 23.9 million hectares by January 2020, attention needs to be focused on strengthening the effectiveness of MPA management. Consolidating and expanding protection of Indonesia’s marine resources is critical with increasing pressure from a fast-expanding population, illegal, unreported, and unregulated fishing, pollution, coastal development, unsustainable tourism and climate change. Biodiversity conservation must therefore concurrently consider multiple economic sectors such as fisheries and tourism, and their synergies with MPA management. This paper aims to outline the current landscape of fisheries and marine tourism pertaining to area-based conservation in Indonesia, to inform and support improved integration into effective MPA management. Four areas to focus efforts were identified: diversification of governance types of community-based management, improved coordination between fisheries and MPAs during planning and management implementation, the development and support of pathways for sustainable tourism, and planning for future conditions. Sustainable development for fisheries and tourism must be incorporated into all aspects of MPA management, whilst recognising that current management systems are insufficient to ensure long-term sustainability for natural resources and local communities, and strategies need to increase resilience of social-ecological systems in anticipation of future conditions

Predator presence alters prey diet composition but not quantity in tide pool fish interactions

Understanding species interactions and how they change in the presence of a predator or competitor is a fundamental goal for ecologists. We tested such interactions in an intertidal soft sediment pool system where both the sand goby Favonigobius lentiginosus and post-settlement whiting Sillago spp. consume meiofaunal prey, but F. lentiginosus also consumes Sillago spp. We quantified changes in fish gut content volumes and composition (i.e. meiofaunal group diversity and abundances) in response to the presence of a predator/prey and to different fish densities (two, four or six total individuals) in experimental aquaria. We found no significant density-dependent effects on either the predator or prey species, likely due to meiofaunal prey oversupply; however, the diet composition of the prey species Sillago spp. changed significantly in the presence of their potential predator. We conclude that lower consumption of meiofaunal amphipods in the presence of gobies suggests that whiting perhaps maintain their gut fullness by preferentially targeting larger amphipods.Griffith Sciences, Griffith School of EnvironmentNo Full Tex

Lyngbya majuscula blooms and the diet of small subtropical benthivorous fishes

Increasing concerns about the ecological impacts of ongoing and possibly worsening blooms of the toxic, carcinogenic cyanobacteria Lyngbya majuscula in Moreton Bay, Australia, led us to assess differences in meiofaunal prey assemblages between bloom and non-bloom substrates and the potential dietary impacts of dense L. majuscula blooms on the omnivorous benthivore, the Eastern Long-finned Goby, Favonigobius lentiginosus and the obligate meiobenthivorous juveniles of Trumpeter Whiting, Sillago maculata. Marked differences in invertebrate communities were found between sandy and L. majuscula bloom foraging substrates, with copepods significantly more abundant (18.49% vs. 70.44% numerical abundance) and nematodes significantly less abundant (55.91% vs. 1.21% numerical abundance) within bloom material. Gut analyses showed that bentho-planktivorous fishes exposed to L. majuscula in captivity had consumed a significantly greater quantity of prey by both total number (P < 0.0019) and volume (P < 0.0006) than fish exposed to sand treatments. Thus, it is likely for such fishes that L. majuscula blooms increase rates of prey encounter and consumption, with consequent changes in trophic relationships through shifts in predator-prey interactions between small benthivorous fishes and their meiofaunal prey

Key questions for research and conservation of mesophotic coral ecosystems and temperate mesophotic ecosystems.

Mesophotic coral ecosystems (MCEs) and temperate mesophotic ecosystems (TMEs) have received increasing research attention during the last decade as many new and improved methods and technologies have become more accessible to explore deeper parts of the ocean. However, large voids in knowledge remain in our scientific understanding, limiting our ability to make scientifically based decisions for conservation and management of these ecosystems. Here, we present a list of key research and conservation questions to enhance progress in the field. Questions were generated following an initial open call to MCE and TME experts, representing a range of career levels, interests, organizations (including academia, governmental, and nongovernmental), and geographic locations. Questions were refined and grouped into eight broad themes: (1) Distribution, (2) Environmental and Physical Processes, (3) Biodiversity and Community Structure, (4) Ecological Processes, (5) Connectivity, (6) Physiology, (7) Threats, and (8) Management and Policy. Questions were ranked within themes, and a workshop was used to discuss, refine, and finalize a list of 25 key questions. The 25 questions are presented as a guide for MCE and TME researchers, managers, and funders for future work and collaborations

Key Questions for Research and Conservation of Mesophotic Coral Ecosystems and Temperate Mesophotic Ecosystems

Mesophotic coral ecosystems (MCEs) and temperate mesophotic ecosystems (TMEs) have received increasing research attention during the last decade as many new and improved methods and technologies have become more accessible to explore deeper parts of the ocean. However, large voids in knowledge remain in our scientific understanding, limiting our ability to make scientifically based decisions for conservation and management of these ecosystems. Here, we present a list of key research and conservation questions to enhance progress in the field. Questions were generated following an initial open call to MCE and TME experts, representing a range of career levels, interests, organizations (including academia, governmental, and nongovernmental), and geographic locations. Questions were refined and grouped into eight broad themes: (1) Distribution, (2) Environmental and Physical Processes, (3) Biodiversity and Community Structure, (4) Ecological Processes, (5) Connectivity, (6) Physiology, (7) Threats, and (8) Management and Policy. Questions were ranked within themes, and a workshop was used to discuss, refine, and finalize a list of 25 key questions. The 25 questions are presented as a guide for MCE and TME researchers, managers, and funders for future work and collaborations