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Marine biota are redistributing at a rapid pace in response to climate change and shifting seascapes. While changes in fish populations and community structure threaten the sustainability of fisheries, our capacity to adapt by tracking and projecting marine species remains a challenge due to data discontinuities in biological observations, lack of data availability, and mismatch between data and real species distributions. To assess the extent of this challenge, we review the global status and accessibility of ongoing scientific bottom trawl surveys. In total, we gathered metadata for 283,925 samples from 95 surveys conducted regularly from 2001 to 2019. We identified that 59% of the metadata collected are not publicly available, highlighting that the availability of data is the most important challenge to assess species redistributions under global climate change. Given that the primary purpose of surveys is to provide independent data to inform stock assessment of commercially important populations, we further highlight that single surveys do not cover the full range of the main commercial demersal fish species. An average of 18 surveys is needed to cover at least 50% of species ranges, demonstrating the importance of combining multiple surveys to evaluate species range shifts. We assess the potential for combining surveys to track transboundary species redistributions and show that differences in sampling schemes and inconsistency in sampling can be overcome with spatio‐temporal modeling to follow species density redistributions. In light of our global assessment, we establish a framework for improving the management and conservation of transboundary and migrating marine demersal species. We provide directions to improve data availability and encourage countries to share survey data, to assess species vulnerabilities, and to support management adaptation in a time of climate‐driven ocean changes.

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Formalin preservation, freezing, and salted and non-salted smoking are often used to preserve fishes. Body proportions of fish show changes upon preservation when applying different preserving techniques; most authors report a decrease in length and some authors report changes in weight and condition factor (k). Four groups of round sardinella (Sardinella aurita) were subjected to the above treatments. Initial fork length (cm) and weight (g) ranged from 8.7 to 10.8 cm and 6.74 to 11.4 g, respectively. All fish decreased in both length and weight, with highly significant (P < 0.05) differences. Condition factor decreased in all treatments except formalin. Percentage reductions in length, weight, and condition factor were 11.0, 68.0 and 54.8% with salted smoking; 13.0, 69.3 and 53.3% with non-salted smoking; 3.0, 14.1 and 6.7% with freezing; and 7.1, 13.3 and 108.1% with formalin preservation, respectively. Shrinkage was the least with freezing, followed by formalin, salted smoking, and nonsalted smoking preservation.

International audience* The status of marine biodiversity in the Eastern Central Atlantic (ECA), especially of coastal and pelagic fishes, is of concern owing to a number of threats including overharvesting, habitat loss, pollution, and climate change combined with inadequate policy responses, legislation, and enforcement.ăă* This study provides the first comprehensive documentation of the presence, status, and level of extinction risk, based on IUCN Red List assessment methodology, for more than 1800 marine species, including all taxonomically described marine vertebrates (marine mammals, sea turtles, seabirds, fishes); complete clades of selected marine invertebrates (sea cucumbers, cone snails, cephalopods, lobsters, reef-building corals); and marine plants (mangroves, seagrasses).ăă* Approximately 8% of all marine species assessed in the ECA are in threatened categories, while 4% are listed as Near Threatened, 73% are Least Concern, and 15% are Data Deficient. Fisheries and overharvesting are the biggest threats to living marine resources in the ECA, with 87% of threatened species across all taxonomic groups affected by both large- and small-scale targeted fisheries, excessive capture as by-catch, or unsustainable harvest.ăă* The results of this study will transform the current state of knowledge and increase capacity for regional stakeholders to identify and enact marine conservation and research priorities, as a number of species are identified as having high conservation and/or research priorities in the region.ăă* Through the process of marine species data collection and risk assessments conducted over the past 5 years, several key conservation actions and research needs are identified to enable more effective conservation of marine biodiversity in the ECA, including increased governance, multilateral collaboration, taxonomic training, and improved reporting of fisheries catch and effort

Anthropogenic factors that negatively impact reef fishes can include changes in life‐history patterns of fisheries‐targeted species. Understanding these impacts on growth and population age structure is essential in the management of exploited populations of fishes. This is the first study to directly compare age and growth for a major fisheries species between east and west populations of a transatlantic reef fish. The main goal of this study was to document age and growth in grey triggerfish Balistes capriscus from coastal waters of Ghana in the Gulf of Guinea (GOG) and compare those with the previous growth studies from that region and with the western Atlantic population. A secondary objective of this study was to evaluate the use of otoliths to age triggerfish and to provide a preliminary comparison with spine‐derived age estimates. The results obtained from this study provided an updated understanding of the growth and age structure of the eastern B. capriscus population in GOG. The authors documented that shifts in population attributes occurred for B. capriscus after its major decline in abundance. The differences in physical and biotic characteristics of the East and West Atlantic regions and the differences in collection methods of samples make direct comparisons of growth parameters difficult. Nonetheless, overall differences in maximum sizes and ages were apparent; the western Atlantic population had a larger maximum size and older maximum age. The authors also documented that sagittal otoliths can be used to provide age estimates for triggerfish species, and otoliths as an ageing structure had better between‐reader precision compared to dorsal spines.