Fisheries Monitoring Research Articles

Long-term environmental data explain better the abundance of the red octopus (Octopus maya) when testing the niche centroid hypothesis

Correlative ecological niche models have been widely used to infer the organisms' environmental suitability; nevertheless, the relationship between this estimated suitability and their abundance is less clear. The ecological theory proposes that the internal structure of a species niche determines its abundance. Specifically, abundance should decrease from the niche centroid to its margins (i.e., distance to the niche centroid-abundance hypothesis - DNC-abundance), showing a negative relationship. This study tested this hypothesis using a high-quality dataset of catch per unit of effort as a proxy of the abundance of the red octopus (Octopus maya) collected during its fishing season in the Yucatan Shelf, Mexico in 2012. Species' niche was estimated with half of the abundance data taken as presence-only records and environmental variables that consisted of temperature and salinity. The remaining data were used to analyze the DNC-abundance. The protocol was repeated using the abundance and environmental data corresponding to each month of the fishing season. The effect of estimating the species niche was also examined using two different environmental datasets: one that matched abundance in a more finely temporal resolution (average values of the corresponding month in 2012 at a resolution of 9 km2) versus another one with a coarser temporal resolution (long-term data: salinity [1955–2006] and temperature [2002−2010] at a resolution of 1 km2). A consistent inverse relationship was found between abundance and distance to the centroid for the most evaluated scenarios, suggesting that niche structure could be informative for fishery monitoring even under climate change scenarios. In addition, contrary to our expectations, relationships were stronger when the coarse temporal resolution variables were used, which suggests that longer temporal environmental conditions may determine population abundance, probably due to seasonal aggregation in the western region of the Yucatan Peninsula.

Spawning aggregation sites of the cubera snapper, Lutjanus cyanopterus, on the continental shelf of Bahia state, Northeastern Brazil

The cubera snapper (caranha), Lutjanus cyanopterus, is an important resource for reef fisheries in Northeastern Brazil, currently classified as Vulnerable (VU) on the Red List of Threatened Species. This species forms large transient reproductive aggregations, concentrating their reproductive efforts in a short period of the year and in specific spawning sites, which have already been well documented in the Caribbean. These aggregations are predictable in time and space, making them considerably vulnerable to overfishing and other sources of anthropic impacts. These tend to reduce the population’s renewal capacity and genetic diversity, thus contributing to the decline of fish stocks and to the process of local extinctions. Between 2009 and 2010 we identified two L. cyanopterus aggregation sites, commonly known as “Caranheiros”, in two sub-areas located at the continental shelf-break zone of Bahia state, Northeastern Brazil, in the East Brazil Shelf Large Marine Ecosystem (LME16), between latitudes 12 °S and 15 °S. The present study aims to (1) describe patterns of spatial and temporal distribution, and the biological characteristics of L. cyanopterus’ catches from line fisheries targeting the specific aggregations in the two Caranheiros sites; and (2) validate the reproductive character of these aggregations through macroscopic evaluation of sexual maturity phases of the fishes caught. We analyzed fisheries and biological sampling data from the catches of artisanal fleets monitored in the two sub-areas between 2005 and 2014. The identified aggregations occur annually from December to May, with capture peaks concentrated in waning to waxing moon phases, in January, February and March. The predominance of mature, pre-spawning and spent (recent spawning) individuals, males and females, in these aggregations revealed the reproductive activity in both sites. Identifying and validating these spawning sites may contribute to the development of recovery and conservation plans for this threatened species. The continuous monitoring of fisheries on aggregations is a priority, aiming to trigger management responses and adaptative fisheries management. Considering these sites are highly vulnerable and have high local socioeconomical importance, especially to traditional fishers, the exact location of the analyzed “Caranheiros” is not revealed in this publication. However, it has been made available to the government agencies responsible for fisheries control and surveillance, as well as for implementing management and conservation measures for the sustainable use of fisheries resources.

Comparative analyses with conventional surveys reveal the potential for an angler app to contribute to recreational fisheries monitoring

Growing interest in apps to collect recreational-fisheries data requires that relationships between self-reported data and other fisheries data are evaluated, and that potential biases are assessed. This study compared results from a mobile-phone application and website for anglers (MyCatch) to results from three types of fisheries surveys — 1 provincial-level mail survey, 2 creel, and 17 gillnet surveys. Results suggest that an app and website can (i) recruit users that have a broad spatial distribution that is similar to conventional surveys, (ii) generate data that capture regional fishing patterns (2218 trips on 289 lakes and 90 streams or rivers), and (iii) provide catch rate estimates that are similar to those from other fisheries-dependent surveys. Some potential biases in app users (e.g., urban bias) and in the relative composition of species caught provincially were identified. The app was not a suitable tool for estimating fish abundance and relative community composition. Our study demonstrates how apps can or cannot provide a complementary data-collection tool for recreational-fisheries monitoring, but further research is needed to determine the applicability of our findings to other fisheries contexts.

Recreational fishing as a source for the monitoring of a critically endangered shark in southern Brazil

This study tested the use of information collected by anglers for the fisheries monitoring of a Critically Endangered shark in southern Brazil. Catch records of Mustelus fasciatus, Critically Endangered at national and global levels, were obtained from local anglers and tourists in five cities in the main area of occurrence of the species in Brazil. Although they were not comparable due to differences in effort, area and fishing gear, results showed an increase in the number of capture records in relation to the data available in the last two decades (from 4 to 32). Adult females and neonates were highest in catches during spring and summer. There was a high percentage of data recovery (total length, total weight, sex and stage of development) and release rate, which indicates that recreational fishing is an important generator of information for this endangered species. Strategies for applying monitoring in the area are discussed.

On-Board Ship Detection for Medium Resolution Optical Sensors.

In recent years there has been an increased interest in ocean surveillance. The activity includes control and monitoring of illegal fisheries, manmade ocean pollution and illegal sea traffic surveillance, etc. The key problem is how to identify ships and ship-like objects accurately and in a timely manner. In this context, currently, many solutions have been proposed based on high resolution optical and radar remote sensing systems. Most often, these systems suffer from two major limitations viz., limited swath, thereby requiring multiple satellites to cover the region of interest and huge volumes of data being transmitted to ground, even though effective per-pixel information content is minimal. Another limitation is that the existing systems are either simulated on ground or built using the non-space qualified/Commercial Of-The-Shelf (COTS) components. This paper proposes an efficient on-board ship detection system/package connected with medium resolution wide swath optical camera. The methodology adopted has three major components, viz., onboard data processing for improving the radiometric fidelity, followed by a ship detection using modified Constant False Alarm Rate algorithm (CFAR) and a false alarm suppression module to mask false identifications. Finally, the package outputs only the locations of the ships, which is transmitted to the ground. The proposed system reduces the effective volume of data to be transmitted and processed on ground and also significantly cuts down the turnaround time for achieving the end objective. The system is built on radiation hardened Field Programmable Gate Array (FPGA) devices to meet the various engineering constraints such as real-time performance, limited onboard power, radiation hardness, handling of multiple custom interfaces etc. The system is tested with one of the medium resolution Multispectral Visual and Near Infra-Red (MX-VNIR) sensor having a spatial resolution of around 50 m and swath of around 500 Kms, which would be flown with one of the upcoming satellites. The systems performance is also verified on ground with Indian Remote Sensing (IRS) Satellite’s Resourcesat’s Advanced Wide Field Sensor (AWiFS) data and the results are found to be quite encouraging as well as meeting the mission objectives.

Transition to timely and accurate reporting: An evaluation of monitoring programs for China’s first Total Allowable Catch (TAC) pilot fishery

Fisheries monitoring is instrumental to effective fisheries management. Stimulated by technology development and management objective evolution, fisheries monitoring faces a transition into a more timely and accurate data reporting scheme. This transition features the replacement of traditional paper logbooks with electronic logbooks (e-logbooks). In 2017, China launched its first total allowable catch (TAC) pilot in Zhejiang Province, with an aim to develop and implement an e-logbook scheme in fisheries monitoring and management. In this study, we investigated the efficacy of e-logbook-based monitoring system against traditional paper logbooks and summarized the important lessons learned from the pilot. We compared the data reported by paper and e-logbooks, examined the role of observers and transshipment vessels in fisheries monitoring, and interviewed stakeholders for their reflections. We found that e-logbooks could improve data quality and report timeliness. However, significant differences were observed between data reported from paper and e-logbooks. These findings matched with the mixed opinions from different users. Fishermen rated e-logbooks poorly due to difficulties in use and frequent malfunctions, while managers, observers and scientists preferred e-logbooks to paper logbooks. Based on quantitative and qualitative analysis, we identified strengths, weaknesses, opportunities, and threats for future implementation of e-logbooks. We also noted that inadequate legislations, fishermen’s low literacy, high training and running cost, and unregulated transshipment could hinder the implementation of e-logbooks. The refined lessons fill the gaps of the evaluation of TAC pilots in China and can contribute to the future application of e-logbooks in China and elsewhere.

Illegal unregulated and unreported fishing: Methods and increasing trends in Lake Naivasha, Kenya

AbstractIllegal, unregulated and unreported (IUU) fishing is a negative social vice that adversely affects global capture fishery production. The inadequate disclosure of IUU methods and trends in fishery waters hampers management actions to curb illegal fishing activities. Seldom have empirical studies been conducted on IUU methods and their trends in Lake Naivasha. Therefore, this study analysed data on the fisheries monitoring, control and surveillance (MCS) during 2012 to 2018 to test for the significance of trends, and compare the enforcement plans to seizures of illegal fishing gear in the lake. The IUU fishing methods included both the types of equipment and the means used to perpetrate illicit capture or acquisition of fish from the lake. The results indicate a 37% reduction of MCS enforcement patrols during 2018 compared to 2012, and a 16% to 100% upsurge in the quantity of seized IUU fishing items. Illegal fishing boats potentially threaten the fishery of Lake Naivasha with an additional fishing effort of 22% above the 176 licensed boats. An average of 10,700 fishing nets seized per year has the potential fishing intensity of 74 gillnets/km2 against an ideal intensity of 12 gillnets/km2. The frequencies of MCS patrols in Lake Naivasha exhibit no particular trends and likely ineffective in deterring the upsurge of IUU activities, or the evolution of new illegal fishing methods. An increased seizure of illegal fishing boats, outboard engines and gillnets could imply their rampant use in IUU fishing activities. These findings merit a multi‐stakeholder participatory approach to identifying the MCS weaknesses and opportunities for sharing resources to strengthen the fishery management efforts in Lake Naivasha.

Vliyaniye techeniy i atmosfernoy tsirkulyatsii na effektivnost' promysla khamsy v period yeye zimovki u Chernomorskogo poberezh'ya Krasnodarskogo kraya

Russian fishermen harvest European anchovy primarily off the Black Sea coast of the Krasnodar Territory during its wintering and wintering migrations. At wintering grounds, temperature conditions become a secondary factor in determining the behaviour of commercial concentration of European anchovy, with wind and currents being the primary factors. Therefore, the aim of this work is to determine the potential use of daily data on water circulation and local atmospheric transport in short-term (1–7 days) forecasting of European anchovy fishing in the Black Sea. The research used the European anchovy fishery monitoring materials for January – March 2019, as well as daily maps of the Black and Azov Seas level anomalies (from satellite altimetry data) and surface atmospheric pressure and temperature in Europe (analysis) for the mentioned period. The dynamics of the catch rate and its relation to altimetry and atmospheric transport indicators in the north-eastern part of the Black Sea were investigated using graphical and correlation methods. This analysis showed that the main factor contributing to increased catches is intensification of northwest currents in the coastal 60-km zone. The effect of atmospheric transport on fishing efficiency depends on the mesoscale eddy structure of the nearshore current field. In the presence of an intense northwest current in the fishing area, southwest atmospheric transports have a positive effect on fishing, while in the presence of an anticyclonic meander of currents, northeast atmospheric transports become effective. The presence of maximum significant relationships when the determinants of fishing performance are shifted by 1–7 days allows making short-term predictions of fishing efficiency.

Deep neural network-based real time fish detection method in the scene of marine fishing supervision

Overfishing of marine fishery is a serious threat to fishery ecological security. Fishing supervision is one of the main ways to maintain marine fishery ecology. In order to improve the intelligence of fishing supervision system, a real time fish detection method based on YOLO-V3-Tiny-MobileNet was proposed. Aiming at the problems of shallow network layers and insufficient feature extraction ability in YOLO-V3-Tiny network, the proposed network takes YOLO-V3-Tiny as baseline and combines it with MobileNet. The proposed network is pre-trained by VOC2012 dataset, and then retrained and tested on Kaggle_ NCFM (The Nature Conservancy Fisheries Monitoring) dataset. The experimental results show that the proposed method has superior performance in parameters number, mean average precision and detection performance, compared with other methods. Compared with the monitoring method of fishing vessel detection on shore supervision, the real time monitoring method can give timely warning to the fishing vessel operators, which is more conducive to fishery ecological protection.

A review of recent studies on the life history and ecology of European cephalopods with emphasis on species with the greatest commercial fishery and culture potential

With the depletion of many commercial fish stocks and an increasing demand for marine protein for human consumption, cephalopods have become more important as a fishery resource. In EU waters, cephalopod stocks are not routinely assessed and exploitation of these species by large-scale fisheries is largely unregulated. For sustainable exploitation, adequate assessment and scientifically-supported management strategies are needed. However, there is still a lack of data on stock status and inadequate knowledge of the life history and ecology of these species. The present review examined more than 200 scientific articles, on life history and ecology of European cephalopods, published since 2013. It describes recent contributions to knowledge in the context of previously identified research priorities, along with recent advances towards sustainable fishing and aquaculture. It also identifies outstanding knowledge gaps. While some priority areas, such as the development of the species identification guides and evaluation of climate change impacts on cephalopods, have seen significant advances, other challenges remain for the future. These include monitoring of the life history traits and fishery status for the main commercially exploited species in the area, implementation of improved species identification methods during scientific surveys and fisheries monitoring, development of tools to identify stock units, and the study of the environmental and anthropogenic impacts on the stocks of cephalopods inhabiting European waters.

Setting the Context for Offshore Wind Development Effects on Fish and Fisheries

Changes to fisheries that result from offshore wind farm (OWF) installations may be considered good or bad depending on various stakeholders’ perspectives. OWFs can act as artificial reefs that may benefit secondary fish production, but such effects may also have ecological consequences. The fisheries exclusion effect that turns some OWFs into no-go areas, hence effectively no-take zones, could provide resource enhancements or redistribution. However, the displacement of fishing effort may have consequences to fisheries elsewhere. Changes in the sensory environment related to sound, as well as electromagnetic fields and physical alterations of current and wind wakes, may have as yet unknown impacts on fisheries resources. Understanding the interactions among effect type, OWF development phase, and spatiotemporal population dynamics of commercial and recreational species remains chal-lenging, exemplified by the commercial fishery lobster genus Homarus in European and North American waters. While knowledge of the interactions between resource species and OWFs is improving, there remain questions on the wider interaction between and consequences of OWFs and fisheries. Studies of this wider relevance should aim to improve understanding of the economic and societal impacts of OWFs linked to ecosystem services that support fisheries. Furthermore, assisting fisheries management and providing advice requires monitoring and survey data collection at appropriate spatiotemporal scales. This information will help to determine whether OWFs have any meaningful impact on regional fisheries, and increased investments will be needed to target scientifically appropriate monitoring of OWFs and fisheries, which is supported by better integrated policy and regulation.

Baseline data for marine protected areas planning and fisheries monitoring: Potential conflicts between recreational IUU and commercial fisheries in the proposed “Taza” MPA (Algeria, SW Mediterranean)

Nowadays, recreational fisheries (REC) have a great impact on marine ecosystems and create conflicts with other human coastal activities such as commercial small-scale fisheries (SSF). In the proposed “Taza” marine protected area (MPA) (Algeria, SW Mediterranean), recreational boat fishing is poorly regulated and its catches remain unmonitored. In addition, a significant number of REC fishers sell their catch illegally, an activity we could refer to as IUU (Illegal, Unreported, and Unregulated) fishing. This study is a good opportunity to evaluate the potential conflicts between recreational IUU and commercial fisheries and can be extremely valuable in terms of MPA planning and fisheries monitoring by providing baseline data for setting up sound fisheries management and conservation plans. Two fishing harbors are located near the proposed “Taza” MPA: Boudis and Ziama. Illegal REC boats from Ziama harbor were studied via a direct observation method of landings developed by the Ifremer (French Research Institute for Exploitation of the Sea). A comparison between illegal REC and SSF boats was highlighted in terms of catches and fishing effort. A total of 54 taxa belonging to 24 families were observed in the catches of the 32 recreational active boats in this harbor between May 2013 and April 2014. The proportion of the harvest attributed to illegal REC represented about 50% of the SSF harvest. Illegal REC in the proposed “Taza” MPA is an important socioeconomic activity which is intensively practiced throughout the year. From November to April, the mean catch was almost the same for both fishing categories. Strong competition between recreational and professional fishers for the natural resources was highlighted as 81% of the 54 caught taxa were present in the catches of both fishing categories (i.e. 44 taxa). Moreover, 4 species of high commercial value were caught exclusively by recreational fishers. Finally, the managers of the proposed “Taza” MPA must address and regulate all fishing activities and use the best available information in order to provide important benefits to marine ecosystems, fishers, and the local population.

Analyzing publicly available videos about recreational fishing reveals key ecological and social insights: A case study about groupers in the Mediterranean Sea

iEcology and conservation culturomics are two emerging research approaches that rely on digital data for studying ecological patterns and human-nature interactions. We applied data mining of videos published on YouTube related to recreational fishing of four species of groupers (family: Epinephelidae) in Italy between 2011 and 2017 to learn whether digital user-supplied data help uncover key spatio-temporal ecological patterns characteristic of the studied species. Our results support an ontogenetic deepening of the dusky grouper (Epinephelus marginatus) as revealed by a positive relationship between body mass and depth of captures declared in spearfishing videos. In addition, the data support a northward expansion of the white grouper (Epinephelus aeneus) because the average latitude associated to the catch was found to be positively correlated with the years when the videos were uploaded on YouTube. Furthermore, the georeferenced data about the white grouper filled a knowledge gap in a well-established international occurrence records dataset. The approach presented here could help mitigating data deficiencies and inform about harvesting patterns shown by recreational anglers and spearfishers. Our work illustrates the value of digital data associated with recreational fishing for advancing fish and fisheries research. The approach can be broadened to larger spatial and temporal scales, and to different species, contributing to a better understanding of macroecological patterns, assessment and conservation of exploited species, and monitoring of recreational fisheries.

Research on Fishery Water Quality Monitoring System Based on 6LoWPAN

A fishery water quality monitoring system, based on 6LoWPAN, is proposed which can automatically implement various kinds of supervising tasks according to the changing environment. This system is applied to water quality monitoring of fisheries, realizing remote automatic online monitoring of water quality parameters such as temperature, salt content, pH, and dissolved oxygen, which have a significant impact on the aquatic product growth environment. The monitoring centre software performs the received data analysis, processing, storage, graphic display and alarm, providing the best growth environment for aquatic products. Compared with the existing fishery water quality monitoring methods, the system uses the IPv6 over IEEE 802.15.4 standard to construct a wireless sensor network. 6LoWPAN technology is easier to integrate into larger networks and easier to integrate with Internet-based services. This system can effectively improve the level of water quality management, reduce the risk of aquaculture, and achieve sustainable development of the aquaculture industry.

A survey-based approach to constructing an abundance index of the pink cusk-eel (Genypterus blacodes) in the fjords of Chilean Patagonia

Chilean Patagonia (41∘00’–57∘00’S) is among the least researched ocean regions in the world but supports commercial fisheries for several fish species, including the pink cusk-eel (Genypterus blacodes). Fishery monitoring of this species in fjords is fragmented, thus limiting the quality and quantity of useful information for stock assessment purposes. We proposed a methodological approach to constructing an abundance index for pink cusk-eel, based on catch per unit of effort surveys in the fjords and inner channels of Patagonia in three administrative regions in Chile (Los Lagos, Aysén, and Magallanes). Information regarding the definition of areas to be sampled and the related operational characteristics were gathered by interviewing fishers. Two research surveys were conducted on board artisanal longline vessels in each administrative region during autumn and spring of 2018. Within each region, 12 fishing grounds were sampled using a standardised protocol for soaking times, number of hooks per line and type of bait, and information was also recorded on target and bycatch species. In the Los Lagos region, the mean catch rate of pink cusk-eel was 3.5 and 4.1 fish/100 hooks on the first and second surveys, respectively. For the Aysén region, the mean catch rate of pink cusk-eel was 1.9 fish/100 hooks in the first survey and 6.6 fish/100 hooks in the second survey. The catch rates of pink cusk-eel on the Magallanes region were low, with only 0.5 fish/100 hooks in the first survey and 0.7 fish/100 hooks in the second survey The main teleost species in the bycatch were tadpole codling (Salilota australis) and rockfish (Helicolenus lengerichi), while the elasmobranch species were dogfish (Schroederichthys chilensis) and yellownose skate (Zearaja chilensis). The mean lengths of pink cusk-eel and tadpole codling showed a latitudinal gradient. This manuscript proposes recommendations and gives insights regarding the design and implementation of surveys over extensive and remote areas with unfavourable weather conditions and where fishery monitoring is fragmented.

Ghost fishing impacts on hydrocorals and associated reef fish assemblages

Ghost fishing is a threat to many marine environments, as lost or discarded fishing gear (e.g., fishing lines, nets) continues to fish by entangling, damaging or killing various organisms. Among the benthic organisms that live on tropical reefs, the group probably most affected, due to their shape, are the branching corals. These corals provide refuge, foraging and breeding sites, especially for fishes and therefore impacts on coral structure could compromise the ecology of associated species. We tested if fishing lines entangled on the branching coral Millepora alcicornis would result in an increase in colony mortality, decrease in abundance and richness of fishes and changes in the behavior of associated reef fish. In the field, we estimated the volume of M. alcicornis colonies and its mortality percentages, and videos were recorded to evaluate abundance and richness of fish assemblages and fish behavior. Our results showed that coral mortality increased with increasing amounts of entangled fishing lines. Fish assemblages were similar in M. alcicornis colonies with or without entangled fishing lines. Nevertheless, we observed a significant decrease in the frequency of feeding attempts in two herbivore fish species (Acanthurus bahianus and Ophioblennius trinitatis) that play an important role in coral-reef dynamics, controlling algae abundances. Therefore, ghost fishing has negative impacts on shallow reef ecosystems, directly affecting branching corals and important coral-fish interactions. Management of tropical shallow reef environments should consider regulation and monitoring of coastal fisheries to ensure reef integrity.

Identification and characterization of trammel net métiers: A case study from the southwestern Sicily (Central Mediterranean)

The high variability of trammel fisheries, due to a marked seasonality in target species and fishing activities needs to be investigated with high spatial and temporal resolution. The present study focuses on trammel net fishery in southwestern Sicily (central Mediterranean Sea) identifying and characterizing the main métiers in relation to some key aspects of the fishery such as the target species, composition of landings, main fishing grounds and time of the year. For this purpose, a multivariate statistical approach based on landings and effort data of the Mazara del Vallo southwestern Sicily, Italy) trammel fleet in the period 2009–2013 was applied. A total of 153 different landed species and four different trammel net métiers were identified. These métiers showed differences in target species (i.e. Sepia officinalis, Palinurus elephas, Mullus surmuletus and a mix of species), fishing season, fishing grounds and dimension of fishing vessels. The métiers identified were significantly different in terms of total average landing per unit of effort (LPUE) with métier 1 targeting M. surmuletus, showing the highest average LPUE (2047 (192 s.e.) g*(h)−1*103 m net) and métier 2 targeting S. officinalis, exhibiting the lowest value (1175 (119 s.e.) g*(h)−1*103 m net).The study provides new knowledge on the dynamics of trammel fisheries in southwestern Sicily also showing that the complex nature of this peculiar fishery should be taken into account in any future sampling program aimed at the monitoring and management of artisanal fisheries in this area and more in general in the Mediterranean Sea.

Estimating maturity from size-at-age data: Are real-world fisheries datasets up to the task?

The size and age at which individuals mature is rapidly changing due to plastic and evolved responses to fisheries harvest and global warming. Understanding the nature of these changes is essential because maturity schedules are critical in determining population demography and ultimately, the economic value and viability of fisheries. Detecting maturity changes is, however, practically difficult and costly. A recently proposed biphasic growth modelling likelihood profiling method offers great potential as it can statistically estimate age-at-maturity from population-level size-at-age data, using the change-point in growth that occurs at maturity. Yet, the performance of the method on typical marine fisheries datasets remains untested. Here, we assessed the suitability of 12 North Sea and Australian species’ datasets for the likelihood profiling approach. The majority of the fisheries datasets were unsuitable as they had too small sample sizes or too large size-at-age variation. Further, datasets that did satisfy data requirements generally showed no correlation between empirical and model-derived maturity estimates. To understand why the biphasic approach had low performance we explored its sensitivity using simulated datasets. We found that method performance for marine fisheries datasets is likely to be low because of: (1) truncated age structures due to intensive fishing, (2) an under-representation of young individuals in datasets due to common fisheries-sampling protocols, and (3) large intrapopulation variability in growth curves. To improve our ability to detect maturation changes from population level size-at-age data we need to improve data collection protocols for fisheries monitoring.

Using a participatory impact assessment framework to evaluate a community‐led mangrove and fisheries conservation approach in West Kalimantan, Indonesia

Abstract Community‐based conservation has been identified as a solution to biodiversity loss, climate change and the reduction of rural poverty. The heterogeneity in social and economic inequalities often acts as a barrier to community engagement in resource management and further inhibits the distributional equity of social and ecological outcomes. This study presents a participatory impact assessment (PIA) framework that evaluated the outcomes of a cross‐sector community‐led conservation initiative. Community members involved in the programme identified activities and outcomes for the conservation cooperative (CC), ranking the influence of the former on the latter as well as their daily life through multiple focus group discussions (FGDs). Participants were asked to rank the impact of activities on outcomes and the scale of the outcome which was totalled to identify the most impactful programme activities and outcomes during the project period. Community members reported improved income, health, education and the creation of a locally led natural resource management system. Members also reported improved crab harvest rates and reduced mangrove deforestation. Environmental outcomes identified by community members through the PIA were verified through a secondary spatial analysis and mud crab independent fisheries monitoring. The results support the hypothesis that environmental non‐governmental organizations (NGOs) need to consider a multi‐dimensional view of human well‐being, and that cross‐sector integrated interventions may be effective at improving multiple outcomes. Future steps should focus on spatial replication of the CC programme which will provide further insights by testing for differences in outcomes between villages, how those are impacted by pre‐existing social and ecological systems and comparing outcomes between control sites that did not receive interventions. A free Plain Language Summary can be found within the Supporting Information of this article.

Illuminating dark fishing fleets in North Korea.

Illegal, unreported, and unregulated fishing threatens resource sustainability and equity. A major challenge with such activity is that most fishing vessels do not broadcast their positions and are "dark" in public monitoring systems. Combining four satellite technologies, we identify widespread illegal fishing by dark fleets in the waters between the Koreas, Japan, and Russia. We find >900 vessels of Chinese origin in 2017 and >700 in 2018 fished illegally in North Korean waters, catching an estimated amount of Todarodes pacificus approximating that of Japan and South Korea combined (>164,000 metric tons worth >$440 million). We further find ~3000 small-scale North Korean vessels fished, mostly illegally, in Russian waters. These results can inform independent oversight of transboundary fisheries and foreshadow a new era in satellite monitoring of fisheries.