Historical baselines of coral cover on tropical reefs as estimated by expert opinion

Coral reefs are important habitats that represent global marine biodiversity hotspots and provide important benefits to people in many tropical regions. However, coral reefs are becoming increasingly threatened by climate change, overfishing, habitat destruction, and pollution. Historical baselines of coral cover are important to understand how much coral cover has been lost, e.g., to avoid the 'shifting baseline syndrome'. There are few quantitative observations of coral reef cover prior to the industrial revolution, and therefore baselines of coral reef cover are difficult to estimate. Here, we use expert and ocean-user opinion surveys to estimate baselines of global coral reef cover. The overall mean estimated baseline coral cover was 59% (±19% standard deviation), compared to an average of 58% (±18% standard deviation) estimated by professional scientists. We did not find evidence of the shifting baseline syndrome, whereby respondents who first observed coral reefs more recently report lower estimates of baseline coral cover. These estimates of historical coral reef baseline cover are important for scientists, policy makers, and managers to understand the extent to which coral reefs have become depleted and to set appropriate recovery targets

Global decline in capacity of coral reefs to provide ecosystem services

Coral reefs worldwide are facing impacts from climate change, overfishing, habitat destruction, and pollution. The cumulative effect of these impacts on global capacity of coral reefs to provide ecosystem services is unknown. Here, we evaluate global changes in extent of coral reef habitat, coral reef fishery catches and effort, Indigenous consumption of coral reef fishes, and coral-reef-associated biodiversity. Global coverage of living coral has declined by half since the 1950s. Catches of coral-reef-associated fishes peaked in 2002 and are in decline despite increasing fishing effort, and catch-per-unit effort has decreased by 60% since 1950. At least 63% of coral-reef-associated biodiversity has declined with loss of coral extent. With projected continued degradation of coral reefs and associated loss of biodiversity and fisheries catches, the well-being and sustainable coastal development of human communities that depend on coral reef ecosystem services are threatened

Biology, Fishery, Conservation and Management of Indian Ocean Tuna Fisheries

The focus of the study is to explore the recent trend of the world tuna fishery with special reference to the Indian Ocean tuna fisheries and its conservation and sustainable management. In the Indian Ocean, tuna catches have increased rapidly from about 179959 t in 1980 to about 832246 t in 1995. They have continued to increase up to 2005; the catch that year was 1201465 t, forming about 26% of the world catch. Since 2006 onwards there has been a decline in the volume of catches and in 2008 the catch was only 913625 t. The Principal species caught in the Indian Ocean are skipjack and yellowfin. Western Indian Ocean contributed 78.2% and eastern Indian Ocean 21.8% of the total tuna production from the Indian Ocean. The Indian Ocean stock is currently overfished and IOTC has made some recommendations for management regulations aimed at sustaining the tuna stock. Fishing operations can cause ecological impacts of different types: by catches, damage of the habitat, mortalities caused by lost or discarded gear, pollution, generation of marine debris, etc. Periodic reassessment of the tuna potential is also required with adequate inputs from exploratory surveys as well as commercial landings and this may prevent any unsustainable trends in the development of the tuna fishing industry in the Indian Ocean

Evolving the narrative for protecting a rapidly changing ocean, post‐COVID‐19

The ocean is the linchpin supporting life on Earth, but it is in declining health due to an increasing footprint of human use and climate change. Despite notable successes in helping to protect the ocean, the scale of actions is simply not now meeting the overriding scale and nature of the ocean's problems that confront us. Moving into a post-COVID-19 world, new policy decisions will need to be made. Some, especially those developed prior to the pandemic, will require changes to their trajectories; others will emerge as a response to this global event. Reconnecting with nature, and specifically with the ocean, will take more than good intent and wishful thinking. Words, and how we express our connection to the ocean, clearly matter now more than ever before. The evolution of the ocean narrative, aimed at preserving and expanding options and opportunities for future generations and a healthier planet, is articulated around six themes: (1) all life is dependent on the ocean; (2) by harming the ocean, we harm ourselves; (3) by protecting the ocean, we protect ourselves; (4) humans, the ocean, biodiversity, and climate are inextricably linked; (5) ocean and climate action must be undertaken together; and (6) reversing ocean change needs action now. This narrative adopts a ‘One Health’ approach to protecting the ocean, addressing the whole Earth ocean system for better and more equitable social, cultural, economic, and environmental outcomes at its core. Speaking with one voice through a narrative that captures the latest science, concerns, and linkages to humanity is a precondition to action, by elevating humankind's understanding of our relationship with ‘planet Ocean’ and why it needs to become a central theme to everyone's lives. We have only one ocean, we must protect it, now. There is no ‘Ocean B’

Fisheries

‘What is already happening’ There is evidence that location where high catches of cod, haddock, plaice and sole occur, as reported by UK commercial fishing vessels, seems to have shifted over the past 80-90 years. Climate change may be a factor but fishing and habitat modification have also had an important effect. Shifting distributions of fish, partly as a result of climate change are having an impact on the effectiveness of some fishery closure areas and on the apportionment of fishery resources between neighbouring countries (e.g. mackerel in the north-east Atlantic). New fisheries have developed for a number of warmer-water species including seabass, red mullet, anchovy and squid. The stock biomass of seabass in the Western Channel has quadrupled since 1985 from 500t, to over 2000t in 2004/5. ‘What could happen in the future’. As a result of climate change, the UK as a whole is expected to benefit from slightly (i.e. +1-2% compared to present) higher fishery yields by 2050, although regions such as the Irish Sea and English Channel may see a reduction. Models suggest that cod stocks in the Celtic and Irish Seas may to disappear completely by 2100, while those in the North Sea are expected to decline. Climate change has been ‗eroding‘ the maximum sustainable yield of cod in the North Sea by around 32,000t per decade. Very little work has been carried out on the social and economic implications of climate change for the UK fishing industry, however calculations suggest that consequences will be significant only for fishery-dependent communities in the North of Scotland and in the southwest England. Ocean acidification may pose a significant threat to the UK shellfish industry, but more research is required

Age, growth, and abundance fluctuation of Jordan’s damsel, Teixeirichthys jordani (Actinopterygii: Perciformes: Pomacentridae), in the southern Taiwan Strait

Background. Information on the age, growth, and abundance fluctuation is important for fisheries conservation and management because stock assessment models rely on these biological parameters. However, the limited biological information makes it difficult to develop the proper and effective management for Jordan’s damsel, Teixeirichthys jordani (Rutter, 1897), which is a part of commercial fisheries, exploited by trawl fishery in the southern Taiwan Strait. Therefore, this study would intend to provide the necessary information about the age, growth, and abundance fluctuation for this species to fill the gap in the current knowledge. Materials and methods. Age and growth of Jordan’s damsel were assessed based on 407 individuals collected in March–November 2006 from the southern Taiwan Strait. Sagittal otoliths were used for the age determination and growth parameters were estimated by three growth functions. According to the Akaike’s Information Criterion corrected for small sample sizes (AICc), the best fitting model was selected. To explore drivers of the Jordan’s damsel abundance in the southern Taiwan Strait, the Spearman rank correlation was used to discuss linkages between a time series (1994~2010) of catch per unit effort (CPUE) of Jordan’s damsel and several forcing factors: fishing, sea surface temperature anomaly (SSTA), the Pacific Decadal Oscillation (PDO), and chlorophyll-a (CHL). Results. The fish age ranged from 0 to 3 years; and the estimated growth parameters of the von Bertalanffy model (the best fitting model) were L∞ = 122.19 mm (standard length), k = 0.316 year−1, and t0 = −2.5477. Spearman rank correlation indicated fishing effort (P 0.05). Conclusion. Teixeirichthys jordani displayed positively allometric growth and this study providing population structure (size and age distribution) and growth parameters would be beneficial for population assessment and fishery management for Jordan’s damsel. For Jordan’s damsel in the southern Taiwan Strait, fishing may cause abundance fluctuations by affecting population dynamics, and biophysical conditions associated with PDO and El Niño-Southern Oscillation (ENSO) may be not adequate to affect the stock fluctuation though CHL and PDO were significant predictors of CPUE

Modelling the effects of climate change on the distribution and production of marine fishes:Accounting for trophic interactions in a dynamic bioclimate envelope model

Climate change has already altered the distribution of marine fishes. Future predictions of fish distributions and catches based on bioclimate envelope models are available, but to date they have not considered interspecific interactions. We address this by combining the species-based Dynamic Bioclimate Envelope Model (DBEM) with a size-based trophic model. The new approach provides spatially and temporally resolved predictions of changes in species' size, abundance and catch potential that account for the effects of ecological interactions. Predicted latitudinal shifts are, on average, reduced by 20% when species interactions are incorporated, compared to DBEM predictions, with pelagic species showing the greatest reductions. Goodness-of-fit of biomass data from fish stock assessments in the North Atlantic between 1991 and 2003 is improved slightly by including species interactions. The differences between predictions from the two models may be relatively modest because, at the North Atlantic basin scale, (i) predators and competitors may respond to climate change together; (ii) existing parameterization of the DBEM might implicitly incorporate trophic interactions; and/or (iii) trophic interactions might not be the main driver of responses to climate. Future analyses using ecologically explicit models and data will improve understanding of the effects of inter-specific interactions on responses to climate change, and better inform managers about plausible ecological and fishery consequences of a changing environment