Remote island nations face a number of challenges in addressing concerns about shark population status, including access to rigorously collected data and resources to manage fisheries. At present, very little data are available on shark populations in the Solomon Islands and scientific surveys to document shark and ray diversity and distribution have not been completed. We aimed to provide a baseline of the relative abundance and diversity of reef sharks and rays and assess the major drivers of reef shark abundance/biomass in the Western Province of the Solomon Islands using stereo baited remote underwater video. On average reef sharks were more abundant than in surrounding countries such as Fiji and Indonesia, yet below that of remote islands without historical fishing pressure, suggesting populations are relatively healthy but not pristine. We also assessed the influence of location, habitat type/complexity, depth and prey biomass on reef shark abundance and biomass. Location was the most important factor driving reef shark abundance and biomass with two times the abundance and a 43% greater biomass of reef sharks in the more remote locations, suggesting fishing may be impacting sharks in some areas. Our results give a much needed baseline and suggest that reef shark populations are still relatively unexploited, providing an opportunity for improved management of sharks and rays in the Solomon Islands.
Seabed mapping can quantify the extent of benthic habitats that comprise marine ecosystems, and assess the impact of fisheries on an ecosystem.In this study, the distribution of seabed habitats in a proposed no-take Marine Reserve along the northeast coast of Great Barrier Island, New Zealand, was mapped using underwater video combined with bathymetry and substratum data.As a result of the boundary extending to the 12 nautical mile Territorial Limit, it would have been the largest coastal Marine Reserve in the country.Recreational and commercial fisheries occur in the region and would be expected to affect species' abundance.The seabed of the study area and adjacent coastal waters has been trawled up to five times per year.Benthic communities were grouped by multivariate cluster analysis into four biotope classes; namely (1) shallow water macroalgae Ecklonia sp. and Ulva sp. on rocky substrata (Eck.Ulv); and deeper (2) diverse epifauna of sponges and bryozoans on rocky substrata (Pon.Bry), (3) brittle star Amphiura sp. and sea anemone Edwardsia sp. on muddy sand (Amph.Edw), and (4) hydroids on mud (Hyd).In biotopes Pon.Bry, Amph.Edw and Hyd, there where boulders and rocks were present, and diverse sponge, bryozoan and coral communities.Fifty species were recorded in the deep water survey including significant numbers of the shallow-water hexactinellid glass sponges Symplectella rowi Dendy, 1924 and Rossella ijimai Dendy, 1924, the giant pipe demosponge Isodictya cavicornuta Dendy, 1924, black corals, and locally endemic gorgonians.The habitats identified in the waters to the northeast of Great Barrier Island are likely to be representative of similar depth ranges in northeast New Zealand.This study provides a baseline of the benthic habitats so that should the area become a Marine Reserve, any habitat change might be related to protection from fishing activities and impacts, such as recovery of epifauna following cessation of trawling.The habitat map may also be used to stratify future sampling that would aim to collect and identify epifauna and infauna for identification, and thus better describe the biodiversity of the area.
Abstract Many researchers have pointed to coastal environments and their use for energy production, aquaculture, and conservation as key to solving profound challenges facing humanity. Navigating this transition in ocean space necessitates tools to quantify impacts on displaced marine users, including recreational fishers. In this study, we present a novel method combining spatial ecological models of recreational catch with fine-scale random utility models of site choice to predict the impacts of site closures on recreational fishing experiences (fisher welfare). We demonstrate our approach by modelling data from over 10 000 fishing trips to fine-scale sites across 1500 km of coastline in the south-west of Australia and simulating the effects of no-take marine reserves recently implemented in the Australian Marine Parks. The results show how the combination of random utility modelling with spatial ecological methods provides a powerful tool for investigating recreational fisheries as joint social-ecological systems and incorporating recreational fishing into marine spatial planning.
This BRUVS data is from the South West Corner Marine Park project and has been downloaded from GlobalArchive (https://globalarchive.org/geodata/data/project/get/275) in February 2022 Individual campaigns within this project can be identified by the collection code within this resource. Taxa have been matched to the World Register of Marine Species (WoRMS). Additional data added from observations in March 2023. GlobalArchive is an online centralised repository of fish image annotation, stereo calibration and associated information that provides the ability to upload data with flexible file formats. It is designed to receive standardised datatable formats directly from EventMeasure (EM) software or from any other image annotation records or historical data sets and provides the ability to explore, query and share this data with other users across different projects and institutions. GlobalArchive is designed for working with annotation data that has already been generated via external sources. It solves the problem of data synthesis providing a centralised repository to work with and query the data, and also provides advanced sharing capability to allow for synthesis and collaboration between users and organisations. GlobalArchive was conceived by Timothy Langlois at the University of Western Australia and brought to life by Ariell Friedman at Greybits Engineering in Sydney.
A global survey of coral reefs reveals that overfishing is driving resident shark species toward extinction, causing diversity deficits in reef elasmobranch (shark and ray) assemblages. Our species-level analysis revealed global declines of 60 to 73% for five common resident reef shark species and that individual shark species were not detected at 34 to 47% of surveyed reefs. As reefs become more shark-depleted, rays begin to dominate assemblages. Shark-dominated assemblages persist in wealthy nations with strong governance and in highly protected areas, whereas poverty, weak governance, and a lack of shark management are associated with depauperate assemblages mainly composed of rays. Without action to address these diversity deficits, loss of ecological function and ecosystem services will increasingly affect human communities.
Abstract It is unknown whether lobster behaviour is sensitive to fishing, as has been previously suggested for fish. This study investigated the impacts of recreational fishing on the wariness of western rock lobster (Panulirus cygnus, George) through comparisons between fished sites and no-take reserves (NTRs) at Rottnest Island. We used visual census to survey the density and size structure of lobster at sites inside and outside three comparable NTRs, and baited remote underwater video to study the behaviour of lobster at comparable sites. The density of legal-sized P. cygnus was twice as high within NTRs (0.34 ± 0.05) than fished sites (0.16 ± 0.03). P. cygnus also spent less time with bait in fished sites (0.42 ± 0.15 min) than NTRs (1.15 ± 0.28 min). This study provides the first evidence that behaviour of decapods, namely P. cygnus, is sensitive to noninjury-related disturbance associated with recreational fishing, with higher wariness in fished areas. Investigation is required into potentially confounding biotic and abiotic factors to further explore the applicability of lobster wariness as an indicator for fishing pressure.
Abstract Climate change is modifying species distributions around the world, forcing some species poleward, where they can alter trophic interactions. Many tropical herbivorous fishes have successfully expanded their ranges into temperate ecosystems, and while it is clear they drive increases in herbivory rates in specific localities, little is known about how they might affect the diversity of herbivory functions across large spatial scales, considering their interaction with assemblages of native herbivores in temperate habitats. We assessed the spatial overlap and habitat associations of native temperate and range‐expanding tropical herbivorous fishes in six subregions of south‐western Australia to determine how incursions of tropical species may have affected the diversity, redundancy (index of uniqueness) and the ‘spatial extent’ (addition of functions in new areas) and ‘intensity’ (increasing density of functional groups) of specific herbivory functions in recipient ecosystems. Tropical herbivores had high abundances in temperate ecosystems, forming schools from 40 (parrotfish) to 200 (rabbitfish) individuals strongly associated with seagrass meadows and reefs with high cover of turf algae. Overlap with temperate herbivores was highest in the northern subregions, forming unique assemblages, with no apparent species displacements. The addition of tropical species increased functional diversity and uniqueness (the complement of redundancy), introducing novel herbivory functions to many locations. Seagrass browsing increased in spatial extent (27%) and intensity (15×), while seaweed browsing and grazing increased in intensity by up to 2.5× in regions with high abundances of tropical herbivores. Our results suggest that the diversity, intensity and spatial extent of different herbivory functions can change as tropical species with different habitat affinities, behaviours and diets shift their distributions poleward. Changes in functional redundancy are likely to be heterogeneous in space and might not increase initially because the diversity of herbivory functions is relatively low in some temperate marine ecosystems. However, there is the potential for greater redundancy as further tropical species arrive, their abundances increase and the spatial and functional overlap of communities rises. A free Plain Language Summary can be found within the Supporting Information of this article.
Abstract The quantity of plastic fishing gear lost to the ocean remains largely undocumented despite its importance for understanding the magnitude of fishery contributions to plastic marine debris and mitigating contamination at the source. This study estimated plastic gear loss from a major Australian pot fishery by interviewing 50 commercial fishers from the West Coast Rock Lobster Managed Fishery in 2021 to document the plastic gear components used, the number of pots lost, and the causes for gear loss. The estimated annual percentage of gear lost (10.8%) and rate of “active” gear loss by fishing effort (0.2%) were lower than global estimates for other pot fisheries indicating that plastic gear loss from this commercial fishery is relatively low. Plastic gear loss was attributed to rope (47.0%), pot components (30.7%), and floats (22.3%), of which 78.0% were polypropylene and polyethylene. The composition of pots, measures used to prevent gear loss, and changes to management could influence plastic gear loss from this fishery. This is the first study to examine plastic gear loss from an Australian pot fishery with a dynamic approach that provides robust estimates for better understanding plastic gear loss from fisheries and informing plastic mitigation efforts.
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