Negligible recovery in Chagos holothurians (sea cucumbers)

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Characterizing tourism benefits associated with top‐predator conservation in coastal British Columbia

1. Facing public concern over costs related to top‐predator reintroductions and conservation, ecosystem services such as ecotourism are often used to evoke benefits that outweigh or offset those costs. Quantifying these benefits using rigorous scientific methods can provide confidence to policymakers and other stakeholders that predators can in fact deliver positive outcomes to people living alongside them. The evaluation of these benefits is often anecdotal or qualitative, however, and empirical quantifications are rare.
2. In coastal marine ecosystems, sea otter reintroduction is seen as a conservation success to some but a bane to others. The contribution of sea otters (Enyhdra lutris) to tourism revenue is touted as a crucial ecosystem service benefit to offset the loss of shellfish harvesting and associated revenue, but remains unquantified, weakening the favourable reception of conservation action.
3. The potential economic benefits of sea otters associated with tourism and the extent to which benefits are realized were evaluated based on: (i) choice‐experiment surveys of tourists; and (ii) interviews with tourism operators in British Columbia.
4. Sea otters were a strong factor in people's choices regarding wildlife viewing, and sea otters could have large benefits for local economies. Alongside socio‐economic characteristics, tourism experience influences tourists’ preferences. Tourism operators did not perceive sea otters as strongly influencing tourist choice, highlighting the gap that can occur between the perception and the reality of tourist preferences, leading to missed opportunities for the alignment of economic development with conservation actions.

     

Diversity and origins of giant guitarfish and wedgefish products in Singapore

1. Giant guitarfishes (Glaucostegidae) and wedgefishes (Rhinidae) are some of the most threatened marine taxa in the world, with 15 of the 16 known species exhibiting global population declines and categorized as Critically Endangered according to the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. The recent inclusion of all species in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) necessitates more rigorous enforcement by regulatory authorities.
2. Challenges in regulating the trade of giant guitarfish and wedgefish products due to difficulties in visual identification of processed products and labelling issues impede enforcement. The aim of this study is to characterize the diversity and origins of associated traded products that were commercially available in Singapore, one of the world's top importers and re-exporters of shark and ray products.
3. A total of 176 samples of elasmobranch products were obtained between June and December 2019 from fishery ports and various retailers in Singapore. By applying cytochrome c oxidase subunit I gene barcoding, 31 elasmobranch species were detected, with 55% of the species considered threatened (Critically Endangered, Endangered, or Vulnerable) based on the IUCN Red List and 35% of species listed in CITES Appendix II. Four species of giant guitarfishes and wedgefishes were commercially available to consumers in fresh forms of whole fish, fillet, and fin, as well as dried and cooked meats.
4. DNA barcoding has proven to be an effective tool for identifying elasmobranch products that are impossible to recognize visually and would aid enforcement of CITES trade regulations. This work underscores the urgent need to step up enforcement of marine wildlife regulations and draw public attention to the elasmobranch trade.

     

Reef shark declines in remote atolls highlight the need for multi‐faceted conservation action

• 1. The decline of large‐bodied predatory species in the oceans is a concern both from a sustainability perspective and because such species can have important ecological roles. Sharks are particularly vulnerable to fishing as their life histories are characterized by late age at maturity, large body size, and low fecundity.
• 2. Substantial shark population declines have been documented for a number of coastal and pelagic systems, with high population abundance limited to a few remote locations. The relative abundance and composition of reef shark populations are assessed from 1975 to 2006 at a remote, largely uninhabited, group of atolls in the central Indian Ocean; the Chagos Archipelago.
• 3. Number of sharks observed per scientific dive declined from a mean of 4.2 in the 1970s to 0.4 in 2006, representing a decline of over 90%. Silvertip sharks displayed an increase in abundance from 1996, whereas blacktip and whitetip reef sharks were rarely encountered in 2006.
• 4. Poaching in the archipelago, is the most likely cause of these declines, highlighted by a number of illegal vessels containing large numbers of sharks arrested since 1996. The data highlight that shark populations, even in remote, otherwise pristine, marine areas, are vulnerable to distant fishing fleets, and a range of strategies will need to be used in concert for their conservation. Copyright © 2010 John Wiley & Sons, Ltd.

     

Identifying historical baseline at the onset of exploitation to improve understanding of fishing impacts

1. Marine communities have long been impacted by human activities, but the quantification of human‐driven changes often relies on recent data. This is because historical data on fish populations are lacking and are challenging to include in contemporary stock and ecological assessments. As a result, the impacts of early fishing pressure on marine communities are generally poorly documented worldwide.
2. Marine communities of Southeast Australia have a relatively short history of exploitation compared with other temperate systems and were sampled before and after the onset of commercial fishing. As such, they provide a rare opportunity to identify historical baselines and to understand ecological changes after the onset of commercial exploitation.
3. This study compares survey data collected around Tasmania, Southeast Australia, in 1909–1910 with data from the 1980s. The period considered precedes the establishment of a trawl fishery in Southeast Australia in 1915, of other important commercial fisheries in Tasmania, and of a fisheries data collection programme in 1984. Nominal catch rates are used to examine changes across all families of demersal fish recorded in catches and generalized linear models are used to estimate and compare standardized indices of abundance between the 1909–1910 and 1980s data for key commercial families.
4. Results show significant, and thus far unreported, fishing‐induced changes in marine communities after the establishment of commercial fishing in the region. Changes mostly relate to shifts in catch composition and steep declines in the abundance of the main commercial families.
5. This study illustrates a method for analysing low‐quality historical catch data and provides estimates of pre‐commercial fishing abundance that can be included in stock and ecological assessments. More broadly, this study demonstrates the significant role of early fishing in shaping marine communities and increases our understanding about general patterns of exploitation that have been difficult to identify with longer but less detailed fishing histories.

     

New invasive predator reduces the abundance of native prey in a cold-temperate marine fouling community

1. Invasive species threaten the conservation of marine environments, and urgent management strategies are needed to prevent their introduction, establishment and spread. Specifically, marine invasive predators destabilize ecological interactions and alter community structure and function. However, most of the evidence showing the effect of these predators is restricted to a few species and regions, while for others the information remains scarce.
2. This study experimentally evaluated the ecological effects of the sea slug Pleurobranchaea maculata, a recently introduced invasive predator, on the fouling communities of a cold-temperate port in the South-western Atlantic.
3. The results show that increasing predation pressure reduces significantly the abundance of sea anemones, which are among the preferred prey items.
4. This study reveals new evidence to help better understand the effects of P. maculata on the biological communities of a recently invaded region. Furthermore, it provides the first experimental evidence supporting the hypothesis that marine invasive predators can induce a significant decrease in the abundance of native species in benthic communities of cold-temperate marine environments in the South-western Atlantic.

     

Long-term catch trends and risk assessment of the Critically Endangered white-spotted wedgefish (Rhynchobatus djiddensis) from South Africa

1. The white-spotted wedgefish (Rhynchobatus djiddensis) is a Critically Endangered shark-like ray in the family Rhinidae. Throughout its Western Indian Ocean distribution, it is targeted for its valuable meat and fins and is reported to have undergone major population declines. However, there remains a need for species specific time-series data to accurately assess localized population declines.
2. This study used two independent long-term (37 and 40 years) time-series catch data from competitive shore angling and shark nets to investigate the size composition and catch per unit effort (CPUE) and conduct a risk assessment for the population on the east coast of South Africa.
3. From 1977 to 2017 the competitive shore fishery captured 7,703 individual R. djiddensis, whilst shark nets in the same region captured 2,856 individuals from 1981 to 2017. Individuals captured in the nets had a sex ratio of 1.8:1 females to males, and were larger than those caught by the anglers. Although the mean annual sizes of net-caught individuals were above the size of reported sexual maturity, there was little evidence to suggest that any individuals captured were reproductively active.
4. Both the competitive shore fishery and shark net catches exhibited strong seasonal trends with the majority of R. djiddensis catches occurring from October to May peaking in austral summer. Standardized CPUE from the competitive shore fishery declined substantially between 1977 and 2017 and shark net catches exhibited a significant (p < 0.05) fourfold decline in annual nominal CPUE from 1981 to 2017.
5. Ultimately, a risk assessment showed a 65.1% decline in abundance over a period of three generation lengths, which indicates that the sampled population of R. djiddensis in South Africa should be classified as Endangered according to the IUCN Red List using criterion A2b. The conservation implications of this are discussed.

     

Effects of off‐bottom shellfish aquaculture on winter habitat use by molluscivorous sea ducks

• 1. Shellfish farming is an expanding segment of marine aquaculture, but environmental effects of this industry are only beginning to be considered.
• 2. The interaction between off‐bottom, suspended oyster farming and wintering sea ducks in coastal British Columbia was studied. Specifically, the habitat use of surf scoters (Melanitta perspicillata) and Barrow's goldeneyes (Bucephala islandica), the most abundant sea duck species in the study area, was evaluated in relation to natural environmental attributes and shellfish aquaculture.
• 3. The extent of shellfish farming was the best‐supported habitat variable explaining variation in surf scoter densities, and the only habitat attribute from the considered set that was a strong predictor of Barrow's goldeneye densities. In both cases, the findings indicated strong positive relationships between densities of sea ducks and shellfish aquaculture operations. These relationships are presumably the result of large numbers of wild mussels (Mytilus trossulus) that settle and grow on aquaculture structures and are preferred prey of these sea ducks.
• 4. Previous work has shown that aquaculture structures provide good conditions for recruiting and growing mussels, including refuge from invertebrate predators, which in turn provides higher densities of higher quality prey for sea ducks than available in intertidal areas. This offers a rare example in which introduction of an industry leads to positive effects on wildlife populations, which is particularly important given persistent declines in numbers of many sea ducks.

Copyright © 2008 John Wiley & Sons, Ltd.     

Assessing the extent to which temporal changes in waterbird community composition are driven by either local,regional or global factors

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Newly developed microsatellite markers for the pan‐European duck mussel,Anodonta anatina: revisiting the main mitochondrial lineages

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Effects of sea-level rise and storm-enhanced flooding on Pacific harbour seal habitat: A comparison of haul-out changes at the Russian and Eel river estuaries

1. Patterns and changes in the distribution of coastal marine mammals can serve as indicators of environmental change that fill critical information gaps in coastal and marine environments. Coastal habitats are particularly vulnerable to the effects of near-term sea-level rise.
2. In California, Pacific harbour seals (Phoca vitulina richardii) are a natural indicator species of coastal change because of their reliance on terrestrial habitats, abundance, distribution, and site fidelity. Pacific harbour seals are marine top predators that are easily observed while hauled out at terrestrial sites, which are essential for resting, pupping, and moulting.
3. Although increasing inundation from recent sea-level rise and storm-driven flooding has changed the Californian coastline, little is known about the effect of future sea-level rise and increased storm frequency and strength on harbour seal haulout site availability and quality in California.
4. Harbour seal habitat was modelled at two sandbar-built estuaries under a series of likely sea-level rise and storm scenarios. The model outputs suggest that, over time, habitat at both estuaries decreased with increasing sea level, and storm-enhanced water levels contributed significantly to habitat flooding. These changes reflect pressures on coastal habitats that have an impact on human and natural systems.

     

Assessment of a terrestrial protected area for the conservation of freshwater biodiversity

1. Freshwater ecosystems are essential to human well-being and most have high biodiversity. However, this biodiversity has been suffering severe declines owing to the expansion of human activities. Protected areas (PAs) are essential for biodiversity conservation and have proved to be successful in stopping species extirpation if managed properly. Unfortunately, they are usually focused on terrestrial biodiversity, leaving freshwater ecosystems aside.
2. The main goal of this study was to determine the influence of a PA (Montesinho Natural Park (MNP), Portugal) on freshwater biodiversity. Aquatic macroinvertebrates and fishes were surveyed, and biodiversity (richness, abundance, Shannon-Wiener diversity, and Pielou's evenness) and water quality (IASPT) indices were calculated inside, at the periphery and outside the MNP.
3. Results showed that the PA does not affect positively either water quality or the two faunal groups monitored. Macroinvertebrate communities were not influenced by the PA; however, the abundance of pearl mussel Margaritifera margaritifera was significantly higher and size was significantly lower inside the MNP. The richness and abundance of fish communities were significantly higher outside the MNP, except for trout Salmo trutta abundance which was higher inside the MNP.
4. Given these results, the MNP does not guarantee the safeguard of overall aquatic biodiversity and habitats and we propose an extension of MNP to downstream areas in order to increase the number of species (mostly cyprinids) under legal protection. This work demonstrates that terrestrial PA planning and management should also consider aquatic biodiversity to achieve successful conservation.

     

The status of harbour seals (Phoca vitulina) in the UK

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Local management to support local fisheries: Rāhui (temporary closure) and bag limits for blackfoot abalone (Haliotis iris) in southern New Zealand

1. Spatially discrete stocks that vary in life history traits on a reef-to-reef scale present a challenge for fisheries managers. Nationally or regionally applied one-size-fits-all approaches to management fail to account for this variability, and when coupled with fishing pressure this can result in serial depletion and localized extinction.
2. Where mechanisms for local management exist, as they do in New Zealand via customary protection areas (Taiāpure Local Fisheries, Mātaitai Reserves), managers have the opportunity to trial tools on scales relevant to the stocks managed. This study assesses the effect of bag limits and a rāhui (temporary closure) in managing the spatially discrete, and culturally important, blackfoot abalone (Haliotis iris, pāua) in the East Otago Taiāpure, in southern New Zealand.
3. Using surveys spanning 8 years and 26 sites, the rāhui was found to have had mixed results: halting the decline in pāua density at 0 m but not 0.5 m depths. The rāhui did, however, result in an increase in the percentage of individuals above the minimum legal size at both depths.
4. Where bag limits alone had been applied, pāua densities and the percentage of legal-sized individuals continued to decline over the 8-year period, with the loss of large individuals, translating into a decline in estimated egg production.
5. Growth estimates from mark–recapture and surveys of juvenile abundance at sites inside and outside the rāhui highlight the fine-scale variability in pāua life history even within this local area. This suggests there may be biological impediments to pāua management using bag limits alone.
6. Though pāua restoration efforts have had mixed results to date, this study highlights the potential for legally empowered local managers and communities to respond to fisheries declines in their own local area in an action-driven, adaptable, and timely way.

     

The Big Seaweed Search: Evaluating a citizen science project for a difficult to identify group of organisms

1. The Big Seaweed Search invites people to survey UK seashores for 14 conspicuous seaweeds. The science investigates: (i) impact of sea temperature rise; (ii) spread of non-native species; and (iii) impact of ocean acidification. Survey data submitted between June 2016 and May 2020 were analysed to evaluate and explore project directions in relation to citizen science project development.
2. Of the 378 surveys submitted, 1,414 people participated, contributing 1,531 person hours. Surveys were undertaken around the UK, with the highest proportion (46.7%) in the south west and the lowest (3.7%) in the north east.
3. After data verification, 1,007 (54%) records were accepted. Fucus serratus had the highest number of entries correctly identified (66%) and Undaria pinnatifida the lowest (5%), inferring that at least some seaweeds can be difficult to identify, although the overall misidentification rate was relatively low (c. 15%).
4. Apart from Alaria esculenta, U. pinnatifida and Saccharina latissima, the large brown seaweeds were abundant on at least some shores. Non-natives Sargassum muticum and Asparagopsis armata, were band-forming but in low numbers. Coralline algae, whilst band-forming on some shores, were most commonly patchy or sparse in abundance. Revisits, i.e. repeat surveys, at the same site with an interval of at least 1 year, are relatively low, with 18 sites revisited once and three sites revisited twice. Currently, data are insufficient to determine whether any changes in abundance could be detected.
5. This study highlights areas where project developments can enhance data quality and quantity, e.g. better identification resources, training programmes for dedicated volunteers, and an annual focus week of activities. The project framed around climate change impacts, aims to raise awareness of the ecological importance of, and threats faced by, this understudied habitat and introduce conservation concepts including the need to protect common species showing signs of decline.

     

Where have all the sawfishes gone? Perspectives on declines of these Critically Endangered species in Sri Lanka

1. All five species of sawfishes (family Pristidae) are amongst the most threatened marine fishes in the world, with steep population declines and local extinctions documented across their ranges.
2. Sawfishes have featured in Sri Lankan species checklists since 1889. However, landing records are extremely rare and little information is available on their status, diversity, and recent occurrences.
3. Interviews were conducted with 300 fishers and 10 fish traders. Only 39% of fishers (n = 118) could identify sawfishes, 37% had seen sawfishes (although half not since 1992), and only 10.7% had ever caught one. No respondents under 30 years could identify sawfishes. Older respondents (>50 years) were more likely to have caught sawfishes and reported seeing them frequently until 30 years ago, while younger respondents had only seen them at landing sites and, at most, once or twice in their life. Only 10 respondents had seen a sawfish in the last decade, suggesting that sawfishes were relatively abundant in the past but that populations have drastically declined.
4. Of the 32 respondents who had caught sawfishes, 30 reported declining numbers and attributed it to fishing pressure. These steep declines coincide with the time of increased fishing effort, the development of the aquaculture industry, and resulting degradation of coastal habitats in the 1980–1990s.
5. Overall, sawfishes had little cultural significance although fishers had specific names for the different species occurring here and rostra were sometimes donated to Catholic churches for ‘good luck’. Landed sawfishes were primarily sold for meat and traders appeared unaware of the high value of fins.
6. It is likely that sawfishes are now functionally extinct as a component of coastal ecosystems in Sri Lanka. Immediate action including species-specific legislation and critical habitat protection is urgently needed to provide remaining sawfishes and other sharks and rays with a fighting chance.

     

Is the protected Atlantic cod (Gadus morhua) population in Gilbert Bay,Labrador, nearing a tipping point?

1. The Gilbert Bay Marine Protected Area (MPA), Labrador, was created in 2005 to protect a resident, locally adapted population of Atlantic cod and its habitat. Twenty years of monitoring has shown a 90% decline in this bay-cod population since the creation of the MPA.
2. The decline of large commercial-sized cod in the bay was accompanied with increases in the abundance of other fish species, including rock cod (Gadus macrocephalus ogac), sculpin (Myoxocephlalus scorpius), and winter flounder (Pseudopleuronectes americanus), suggesting loss of strong top-down community control.
3. These changes suggest a positive feedback mechanism leading to a fish community tipping point, which could severely impact the recovery potential of the protected Atlantic cod population in the MPA.
4. We suggest that managers should be including this possibility in their management decisions for the Gilbert Bay MPA.

     

Sun coral management effectiveness in a wildlife refuge from south-eastern Brazil

1. The introduction of exotic species is one of the major causes for biodiversity loss in marine environments. Introduced species can change habitat complexity, impacting local communities and altering ecosystem functioning.
2. Since the 1980s, the scleractinian species Tubastraea coccinea and Tubastraea. tagusensis (commonly known as sun corals) have been spreading in the south-western Atlantic, posing a major threat to local biodiversity and marine ecosystems. Nowadays, these species are reported from more than 3,500 km along the Brazilian coast and on at least 21 oil and gas offshore platforms.
3. Considering the great environmental pressure resulting from sun coral invasion, this study verified the effectiveness of manual removal of Tubastraea spp. along a rocky shore in Alcatrazes Wildlife Refuge, one of the most pristine marine regions in Brazil.
4. Results indicate that removal is indeed effective as a control technique; however, as invaders have high regeneration capabilities and recruitment rates, successive management efforts are essential. In order for management to be effective against Tubastraea's year-round release of clonal larvae, results suggest invaded areas should receive at least two management actions per year.
5. Successive management efforts, in addition to the development of new techniques and prevention of new invasions should be priorities for mitigating sun coral impacts.

     

Novel insights into the marine phase and river fidelity of anadromous twaite shad Alosa fallax in the UK and Ireland

1. Most research on anadromous fishes has been invested in their freshwater life‐phases, resulting in a relatively sparse understanding of their spatial ecology during marine life‐phases. However, understanding the marine dispersal of anadromous fishes is essential to identify threats and to implement conservation measures that fully encompass their lifecycle.
2. The twaite shad Alosa fallax is an anadromous fish increasingly imperilled across its range due to pollution, harvesting, and impediments to freshwater migration, but little is known about its distribution and movements during its marine life‐phase. Here, the application of acoustic telemetry provided novel insights into the coastal dispersal of twaite shad in the UK and Ireland during 2018–2019, and the freshwater entry of individuals during the 2019 spawning season.
3. Of 73 twaite shad acoustic‐tagged during their upstream migration in the River Severn in May 2018, 58 emigrated from the river. Twelve were subsequently detected 200 km to the south‐west at the Taw–Torridge Estuary between July 2018 and April 2019, where estuarine movements up to 5.8 km inland occurred in summer, winter, and spring. One was subsequently detected in the Munster Blackwater Estuary (Ireland) and then in the River Severn, indicating a minimum movement distance of 950 km. Thirty‐four (59%) of the emigrating individuals from 2018 re‐entered fresh water in the rivers Severn (n = 33) and Wye (n = 2) in April and May 2019.
4. These results suggest year‐round use of estuarine and nearshore habitats by at least a subset of the twaite shad population during their marine phase, providing evidence of potential range overlap between populations that spawn in different areas in the UK and Ireland, which may be facilitated by substantial dispersal. The results also highlight the potential of telemetry for estimating freshwater and marine mortality, and the benefits of sharing detection data across networks.