Baited Remote Underwater Video (BRUV) has become a popular technique to survey fish assemblages for a wide range of purposes. BRUV methodology has, however, also varied greatly for a range of reasons. A major dichotomy occurs, in particular, in the time used to sample the fish assemblages i.e. the BRUV set time. The aim of this study was to determine whether differences in set time were likely to affect the conclusions reached by studies using different set times, and what might be the most appropriate and cost-effective set time to use to sample temperate reef fish assemblages. In this study, we test whether there were significant differences between the two main set times used (i.e. 30 and 60 min) in BRUV sampling for assemblage patterns, species diversity, and relative abundance of rocky reef fishes. In particular, we sampled fished and unfished rocky reefs to assess whether the different set times would lead to differences in the patterns or the interpretation of the subsequent data. We sampled fish assemblages on six rocky reefs (20–35 m) across two marine parks on the east coast of Australia. At each location replicate BRUVs were deployed for 30 and 60 min in a ‘no take’ area (marine sanctuary) and a fished area. The interpretations of the data across the fished and unfished zones were consistent with both set times indicating that the conclusions from both set time were comparable. Furthermore, there were no differences in fish assemblages or species richness between the set times. The relative abundances of the recreationally and commercially important snapper (Chrysophrys auratus) were greater in the longer set times, but the actual spatial patterns between zones and amongst locations were consistent. Piecewise regression analysis of the breakpoint times for species accumulation found that there were no significant differences between locations or between fished and unfished areas. Mean breakpoint, the time when species accumulation changes, occurred at 12 min ± 1.04 S.E. for all sites combined whilst the shorter set time was found to be less costly and require less field and laboratory times. This study quantifies that either 30 or 60 min will provide a reasonable estimate of rocky reef fish diversity and relative abundance for comparative purposes, on these shallow rocky reefs.
Operation and maintenance can jeopardise the financial viability of an offshore wind energy project due to the cost of downtime, repairs and, above all, the inevitable uncertainties. The variability of wave climate can impede or hinder emergency repairs when a failure occurs, and the resulting delays imply additional costs which ultimately reduce the competitiveness of offshore wind energy as an alternative to fossil fuels. Co-located wind turbines and Wave Energy Converters (WECs) are proposed in this paper as a novel solution: the reduction of the significant wave height brought about by the WECs along the periphery of the wind farm results in a milder wave climate within the farm. This reduction, also called shadow effect, enlarges weather windows for Operation & Maintenance (O&M). The objective of this paper is to investigate the increase in the accessibility time to the turbines and to optimise the layout for the co-located wind-wave farm in order to maximise this time. The investigation is carried out through a case study: Alpha Ventus, an operating offshore wind farm. To maximise the reduction of wave height in the turbine area no fewer than 15 layouts are tested using high-resolution numerical modelling, and a sensitivity analysis is conducted. The results show that, thanks to the wave energy extraction by the WECs, weather windows (access time) can increase very significantly – over 80%. This substantial effect, together with other benefits from the combination of wave and offshore wind power in a co-located farm (common electrical infrastructures, shared O&M equipment and crews, etc.) will enhance the economic viability of these marine renewables, and hence their potential to reduce our carbon footprint on the planet.
Traditional methods for assessing coastal hazards have not typically incorporated a rigorous treatment of uncertainty. Such treatment is necessary to enable risk assessments which are now required by emerging risk based coastal zone management/planning frameworks. While unresolved issues remain, relating to the availability of sufficient data for comprehensive uncertainty assessments, this will hopefully improve in coming decades. Here, we present a modelling framework which integrates geological, engineering and economic approaches for assessing the climate change driven economic risk to coastal developments. The framework incorporates means for combining results from models that focus on the decadal to century time scales at which coasts evolve, and those that focus on the short term and seasonal time scales (storm bite and recovery). This paper demonstrates the functionality of the framework in deriving probabilistic coastal hazard lines and their subsequent use to establish an economically optimal setback line for development at a case study site; the Narrabeen–Collaroy embayment in Sydney, New South Wales.
Marine debris is a pollution problem on a global scale, which causes harm to marine ecosystems and consequently results in profoundly negative influences on mankind. This type of pollution can originate from various activities such as leisure and tourism, fishery, land-based sources, and vessels, etc. In this study, it was found that derelict fishing gear (DFG) produced by oyster farming activities is being dispersed along the southwestern coast of Taiwan, consequently reducing the leisure quality and coastal amenities. In order to understand the current problem of DFG, related stakeholders were invited to undergo qualitative interviews to observe the stakeholders’ perceptions pertaining to DFG pollution and their opinions on subsequent mitigation measures. The results of the interviews were then used to explore management issues pertaining to DFG, as well as the trans-boundary pollution problems caused by DFG based on the theory of environmental resource governance and scales of management jurisdiction. Finally, suggestions were provided to effectively reduce the DFG pollution from oyster farming, including the strengthening of environmental education and propagation, sustaining management and monitoring of marine debris by the government, using policy tools, and applying solid waste management principles.
This paper details Australian research that developed tools to assist fisheries managers and government agencies in engaging with the social dimension of industry and community welfare in fisheries management. These tools are in the form of objectives and indicators. These highlight the social dimensions and the effects of management plans and policy implementation on fishing industries and associated communities, while also taking into account the primacy of ecological imperatives. The deployment of these objectives and indicators initially provides a benchmark and, over the life of a management plan, can subsequently be used to identify trends in effects on a variety of social and economic elements that may be objectives in the management of a fishery. It is acknowledged that the degree to which factors can be monitored will be dependent upon resources of management agencies, however these frameworks provide a method for effectively monitoring and measuring change in the social dimension of fisheries management.
Essentially, the work discussed in this paper provides fisheries management with the means to both track and begin to understand the effects of government policy and management plans on the social dimension of the fishing industry and its associated communities. Such tools allow the consideration of these elements, within an evidence base, into policy arrangements, and consequently provide an invaluable contribution to the ability to address resilience and sustainability of fishing industries and associated communities.
While ocean acidification (OA) poses a significant threat to ocean-related ecosystems and communities reliant on marine fisheries, aquaculture, and coral reef systems, limited public understanding and awareness can prevent coastal regions from being able to adequately assess the need for OA adaptation or mitigation. This study assessed public understanding of OA and how social and demographic factors influence the public’s concern for OA. The analysis was based on 311 questionnaires from full-time Alaska residents. The results showed that most Alaskans self-reported to have a basic awareness of OA, and subsequently were able to recognize that CO2 emissions related to human activity are the dominant driver of changing ocean conditions. However, there was a low recognition of how natural variability in the marine environment affects OA, and most respondents were not very confident in their understanding of OA-related science. Moreover, even though many communities in Alaska are reliant on commercial and subsistence fishing activities, the respondents had a low awareness of fisheries-related OA risk. Given the ongoing debate associated with climate change research, evaluating CO2 mitigation efforts through the perspective of OA could give individuals an unbiased way to assess the pros and cons of more intensive efforts to curb CO2 emissions. Furthermore, using OA communication to enhance the understanding of how natural variability influences OA around the state and the potential economic implications for Alaska fisheries would help residents and stakeholders make informed decisions when considering fisheries management plans, food security, and job diversity as OA intensifies. Solidifying the understanding that any reduction in pH and intensification of OA can have implications for marine species that are irreversible on human timescales will reinforce not only that OA is an immediate concern, but also the importance of taking action now.
Feedbacks occur when advocates engage to clarify the implementation of a policy innovation such as the requirement that federal activities be consistent with objectives of state coastal management plans. Discrete policy feedbacks include advocacy, litigation, appeals of decisions as well as other activities inserted into policy implementation by interests or government agencies acting in their behalf. Feedback analysis is applied to the time after the passage of the 1972 U.S. Coastal Zone Management Act. Conflicts after passage of the law resulted in a negative feedback in the form of a Supreme Court decision in 1984 and a subsequent positive feedback through the 1990 revision of the law effectively reversing the Court decision. New insights documented here suggest that feedback switching, wherein old disputes are moved to new arenas, provides the greatest opportunity for overcoming negative feedbacks that could diminish or eliminate the policy innovation. Furthermore observing feedbacks through time and across multiple policy spaces as demonstrated here provides a robust interpretation of policy evolution from a new perspective. This analysis demonstrates how feedbacks convert a voluntary state program into one with authority over certain federal actions. These findings will be important for other areas of coastal policy and, more broadly, policy evolution in general.
Evaluation of stocking strategies for endangered white abalone (Haliotis sorenseni) has been challenging due to limited data. The present study demonstrated an application of hierarchical demographic model for investigating population dynamics of white abalone and evaluating efficacy of hypothetical restoration strategies. The model represented demographic parameters as multi-level hierarchies, which accounted for uncertainty in parameter estimation due to limited data, and accounted for individual/sub-population variability in demographic traits in response to spatiotemporal heterogeneity. The model also accounted for the Allee effect (i.e., density-dependent fertilization success) observed in white abalone populations. In the calculation of fertilization success, we applied region-specific density estimates from three regions (Tanner Bank, Cortes Bank and San Clemente Island). Elasticity analyses showed that survival affected growth rate more than fertility, and fertility and survival of large-size individuals (>130 mm) had the most influence on growth rate; the mean elasticity to fertility decreased while the one to survival increased as the population became less abundant. Evaluation of stocking strategies suggested that restoration efforts directed at larger-size individuals may be more effective in increasing population density than efforts focusing on juveniles; the degree of increase depended on both initial population density and initial size structure. However, stocking large-size individuals led to a decrease in the intermediate-size class (90–130 mm) proportion in most cases. Efficacy of increasing intermediate-size class proportion heavily depended on initial population density. We suggest that restoration efforts may need to consider the region-specific density-dependence effect, and to balance stocking efficacy and laboratory expenses/time consumption.
The global transformation of the marine nearshore is generating profound losses of ecological and geomorphological functions and ecosystem services, as natural environments are replaced with built. With conservation a diminishing option and restoration often unrealistic, there is a need to rethink development and the potential for marine infrastructure to contribute to net environmental gain. Through analysis of 150 years of change associated with the development of three large-scale marinas in the Seattle area, this research identifies the ways in which evolving policy frameworks and ecological understanding determine the nature, efficiency and environmental outcomes of coastal marine developments. Decisions on infrastructure design, mitigation strategies and policy interpretations directly determined the ecological fate of marine biota inhabiting these structures as well as surrounding ecosystems. In spite of increasing evidence of environmental legislation driving mitigation and innovative engineering, the net ecological trajectories remained negative. There were no tested demonstrations of marine mitigation to confirm which measures would succeed. Where scientific understanding existed, the uptake into planning and legislation was slow. More broadly, this research highlights a need and opportunity to consider marine infrastructure as living laboratories to inform a policy shift from a no-net-loss paradigm to net-environmental-gain. This evolution is timely, with sea level rise requiring new approaches to coastal defenses and with marine energy infrastructure increasingly being located offshore, where there is little knowledge of the ecological changes occurring in both time and space.
Ecosystem-based fisheries management seeks to consider trade-offs among management objectives for interacting species, such as those that arise through predator–prey linkages. In particular, fisheries-targeting forage fish (small and abundant pelagic fish) might have a detrimental effect on fisheries-targeting predators that consume them. However, complexities in ecological interactions might dampen, negate, or even reverse this trade-off, because small pelagic fish can be important predators on egg stages of piscivorous fish. Further, the strength of this trade-off might depend on the extent to which piscivorous fish targeted by fisheries regulate forage species productivity. Here, we developed a novel delay-differential bioeconomic model of predator–prey and fishing dynamics to quantify how much egg predation or weak top-town control affects the strength of trade-off between forage and piscivore fisheries, and to measure how ecological interactions dictate policies that maximize steady-state profits. We parameterized the model based on ecological and economic data from the North Sea Atlantic cod (Gadus morhua) and Atlantic herring (Clupea harengus). The optimal policy was very sensitive to the ecological interactions (either egg predation or weak top-down control of forage by predators) at relatively low forage prices but was less sensitive at high forage fish prices. However, the optimal equilibrium harvest rates on forage and piscivores were not substantially different from what might be derived through analyses that did not consider species interactions. Applying the optimal multispecies policy would produce substantial losses (>25%) in profits in the piscivore fishery, and the extent of loss was sensitive to ecological scenarios. While our equilibrium analysis is informative, a dynamic analysis under similar ecological scenarios is necessary to reveal the full economic and ecological benefits of applying ecosystem-based fishery management policies to predator–prey fishery systems.