Adapting fishing regulations in a highly uncertain environment remains a complex challenge for managers who have to deal with non-linear dynamics of fish population and harvest levels. In this research, a recent method of stochastic control is adapted to a general fishery management problem under multiples sources of uncertainty related to the dynamics of the fish population and the effect of fishing on its growth. The question is about adjusting permanently the management rule or to hold a fixed policy thus avoiding additional noise. The mathematical problem developed here, though oversimplified, represents an original approach to the fishery management issue inspired by the monetary policy challenge of a central bank (Brainard principle). It assumes that Control Variation Increases the level of Uncertainty (namely CVIU approach) under particular conditions, resulting in preferable inaction regions for managers. We specify these conditions to show that the management of a poorly known fishery is still possible by using a CVIU approach.
The need for management approaches based on ecosystem perspectives that thoroughly incorporate ecosystem considerations into marine planning has become increasingly urgent. In response, concepts such as ecosystem-based management (EBM), ecosystem-based approach (EBA) and ecosystem approach (EA) are increasingly being applied in marine/maritime spatial planning (MSP). The purpose of this article is to clarify potential differences and similarities between the three concepts and potential consequences of choosing one over the others. From a questionnaire and literature analysis, the findings showed vast disagreements on how the concepts are related, however the main perception is that the concepts overlap. Respondents agreed that a lack of clear definitions and understandings of the three concepts causes confusion and expect negative consequences for planning outcomes. Eleven principles for how the concepts are ideally performed were found, including; acknowledge interlinkages, see humans as a part of the ecosystem and consider cumulative impacts. While a complete overlap between EBM and EA principles were found, the weighting of each principle was different for each concept. Differences were also found in objectives of the concepts, where definitions of EBM were the only ones to include the objective of co-existence and definitions of EBA the only to include objectives of impact management and good environmental status. As this could have consequences in planning processes and thus in the outcomes, it is crucial that MSP practitioners and stakeholders are aware of different perceptions so that choosing between concepts does not lead to less ambitious or inadequate outcomes.
Populations of Acropora palmata and Orbicella faveolata, two important reef-building corals, have declined precipitously across the Caribbean region since at least the 1970s. Recruitment failure may be limiting population recovery, possibly due to lack of suitable settlement habitat. Here, we examine the effects of algal turfs and algal turfs + sediment, two widely abundant substrate types across the Florida Keys, on the settlement of these two ecologically-important species. We show that sedimentsignificantly impedes coral settlement, reducing settlement 10- and 13-fold for A. palmata and O. faveolata, respectively, compared to turf algae alone. This result is corroborated by our field survey data that showed a strong, negative relationship between the abundance of turf + sediment and the abundance of juvenile corals. Turf algae alone did not reduce coral settlement. Our results suggest that sediment-laden turf algae are detrimental to settling corals, but that turf algae alone may be relatively benign.
Primary considerations for adopting an ecosystem approach to fisheries management (EAFM) as a management approach will involve an expanded scope of fisheries management over conventional approaches; specifically, EAFM will involve a broader scale of management. Development of a sub-regional EAFM plan can complement local, national, and regional fisheries management priorities, as well as help to catalyze management action at multiple levels that may not otherwise occur. A sub-regional EAFM policy planning approach has been undertaken for the Sulu-Sulawesi Seascape (SSS), a sub-region of Southeast Asia. This sub-regional policy planning approach illustrates how “scaling up” EAFM can support relevant international, regional, and other sub-regional fisheries management plans and environmental initiatives, while “scaling down” EAF can support relevant national, provincial/state, and local fisheries management plans in Indonesia, Malaysia and the Philippines.
Low-Elevation Coastal Zones in Central and South America are exposed to climate-related hazards (sea-level rise, climate variability and storms) which threaten the assets (people, resources, ecosystems, infrastructure, and the services they provide), and are expected to increase due to climate change. A non-systematic review is presented focusing on vulnerability elements, impacts, constraints to adaptation, and their possible strategies. The analysis emphasises the Intergovernmental Panel on Climate Change Reasons for Concern (e.g., threatened systems, extreme events, aggregated impacts, and critical thresholds), particularly on sea-level rise, degradation of mangroves, and invasive alien species in Central and South America focusing on case studies from Uruguay and Venezuela. Despite recent advances in coastal adaptation planning in Central and South America, there is an adaptation deficit in the implementation of measures and strategies against climate-related hazards, such as sea-level rise. Adaptation constraints are linked with poverty, resource allocation, lack of political will, and lack of early warning systems for climate-related hazards. Non-structural adaptation measures such as community-based adaptation and ecosystem-based adaptation are not fully mainstreamed into national plans yet. Government-level initiatives (e.g. National Adaptation Programmes of Action) are being developed, but a few are already implemented. In addition to specific thematic measures, the implementation of non-structural approaches, National Adaptation Programmes of Action and early warning systems, based on the reasons for concern, should foster adaptive capacity in coastal areas.
In this study, a general methodology that is based on numerical models and statistical analysis is developed to assist in the definition of marine litter cleanupand mitigation strategies at an estuarine scale. The methodology includes four main steps: k-means clustering to identify representative metocean scenarios; dynamic downscaling to obtain high-resolution drivers with which to force a transport model; numerical transport modelling to generate a database of potential litter trajectories; and a statistical analysis of this database to obtain probabilities of litter accumulation. The efficacy of this methodology is demonstrated by its application to an estuary along the northern coast of Spain by comparing the numerical results with field data. The necessary criteria to ensure its applicability to any other estuarywere provided. As the main conclusion, the developed methodology successfully assesses the litter distribution in estuaries with minimum computational effort.
This final manuscript in the special issue on “Funding for ocean conservation and sustainable fisheries” is the result of a dialogue aimed at connecting lead authors of the special issue manuscripts with relevant policymakers and practitioners. The dialogue took place over the course of a two-day workshop in December 2018, and this “coda” manuscript seeks to distil thinking around a series of key recurring topics raised throughout the workshop. These topics are collected into three broad categories, or “needs”: 1) a need for transparency, 2) a need for coherence, and 3) a need for improved monitoring of project impacts. While the special issue sought to collect new research into the latest trends and developments in the rapidly evolving world of funding for ocean conservation and sustainable fisheries, the insights collected during the workshop have helped to highlight remaining knowledge gaps. Therefore, each of the three “needs” identified within this manuscript is followed by a series of questions that the workshop participants identified as warranting further attention as part of a future research agenda. The crosscutting nature of many of the issues raised as well as the rapid pace of change that characterizes this funding landscape both pointed to a broader need for continued dialogue and study that reaches across the communities of research, policy and practice.
Beaches are economically and socially important to coastal regions. The intensive use of beaches requires active management to mitigate impacts to natural habitats and users. Understanding the patterns of beach use can assist in developing management actions designed to promote sustainable use. We assessed whether remotely piloted aerial systems (commonly known as drones) are an appropriate tool for quantifying beach use, and if beach activities are influenced by environmental conditions. Novel drone-based methods were used to quantify beach use. Drone flights recorded 2 km of beach, capturing video footage of the beach from the dune to water interface and the breaker zone. Flights were undertaken during three school holiday periods at four popular beaches in New South Wales, Australia. These videos were later analysed in the laboratory to categorise beach users. Of the total users sampled, 45.0% were sunbathing, 22.8% swimming, 21.2% walking, 10.6% surfing, and less than 0.5% were fishing. Participation in walking, surfing and fishing was similar throughout the sampling periods. However, sunbathing and swimming significantly increased during the austral spring and summer sampling periods. Usage patterns varied significantly among beaches, and during the different sampling periods, suggesting that adaptive management strategies targeted to specific areas are the most appropriate way to protect beach habitats and users. Furthermore, we demonstrate that drones are an effective assessment tool to improve coastal management decisions.
Marine protected areas (MPAs) have become an increasingly important tool to protect and conserve marine resources. However, there remains much debate about how effective MPAs are, especially in terms of their ability to protect mobile marine species such as teleost and chondrichthyan fishes. We used satellite and acoustic tags to assess the ability of a large oceanic MPA, the British Indian Ocean Territory MPA (BIOT MPA), to protect seven species of pelagic and reef-associated teleost and chondrichthyan fishes. We satellite-tagged 26 animals from six species (Blue Marlin, Reef Mantas, Sailfish, Silky Sharks, Silvertip Sharks, and Yellowfin Tuna), producing 2,735 days of movement data. We also acoustically tagged 121 sharks from two species (Grey Reef and Silvertip Sharks), which were monitored for up to 40 months across a large acoustic receiver array spanning the MPA. We found that the activity spaces of all satellite-tagged animals, including pelagic species, were much smaller than the area of the BIOT MPA, even taking into account errors associated with position estimates. Estimates of space use of acoustically tagged sharks, based on dynamic Brownian Bridge Movement Models (dBBMM), were also much smaller than the size of the MPA. However, we found important limitations when using dBBMM and demonstrate its sensitivity to both study duration and array design. We found that Grey Reef Sharks should be monitored for at least 1 year and Silvertip Sharks for 2 years before their activity space can be effectively estimated. We also demonstrate the potentially important role that intraspecific variability in spatial ecology may play in influencing the ability of MPAs to effectively protect populations of mobile species. Overall, our results suggest that, with effective enforcement, MPAs on the scale of the BIOT MPA potentially offer protection to a variety of pelagic and reef species with a range of spatial ecologies. We suggest that animals need to be tagged across seasons, years, and ontogenetic stages, in order to fully characterize their spatial ecology, which is fundamental to developing and implementing effective MPAs to conserve the full life history of target species.
Climate change and human disturbance threatens coral reefs across the Pacific, yet there is little consensus on what characterizes a “healthy” reef. Benthic cover, particularly low coral cover and high macroalgae cover, are often used as an indicator of reef degradation, despite uncertainty about the typical algal community compositions associated with either near-pristine or damaged reefs. In this study, we examine differences in coral and algal community compositions and their response to human disturbance and past heat stress, by analysing 25 sites along a gradient of human disturbance in Majuro and Arno Atolls of the Republic of the Marshall Islands. Our results show that total macroalgae cover indicators of reef degradation may mask the influence of local human disturbance, with different taxa responding to disturbance differently. Identifying macroalgae to a lower taxonomic level (e.g. the genus level) is critical for a more accurate measure of Pacific coral reef health.