Unmanned underwater vehicles (UUVs) are increasingly used for non-invasive data collection, with applications ranging from supporting fisheries stock assessment to biodiversity mapping. Estimating the area surveyed is crucial to calculate densities and abundances from observations. Area estimation methods range from utilising fixed transect dimensions, to advanced approaches that account for path deviations and intra-transect variability in field of view, often integrating multiple sensors or detailed bathymetric data. However, accuracy of position data from remote vehicles is limited by environmental and operational variability. Compounding these differences, researchers rarely fully document methodologies, preventing comparability between datasets.This paper develops a transferable methodology to process UUV position data, assessing the results of 2 width and 12 length estimation methods on estimated area surveyed. This analysis uniquely includes the calculation of associated error and resulting confidence intervals for each approach. Results show species density estimates can vary up to 13% depending on processing applied. The two equations used to calculate transect width cause significant differences between density estimates. Significant differences in transect length also occur depending on the degree and method of smoothing technique applied to position data. Importantly, these differences between methodologies are encompassed by the variance calculated from the position data.Recommendations to obtain representative transect areas are to validate width equations against laser measurements, use incremental position data and include depth when calculating total distance travelled. Due to variation in resulting density estimates across methods it is essential to include confidence intervals and full details of pre-filtering and smoothing procedures.

Continental shelf and deep ocean ecosystems are increasingly exposed to anthropogenic pressures including commercial fishing and climate change related environmental stressors. Among the most vulnerable taxa are chondrichthyans due to their life histories with low reproductive output and therefore lower rebound potentials. In temperate regions, many chondrichthyan species are expected to undergo poleward distributional shifts in response to ocean warming. However, the extent and drivers of these shifts remain poorly understood, particularly in deep-water environments. This study aims to assess long-term trends in distribution and abundance for three cartilaginous fish species in the Northeast Atlantic Ocean: the rabbitfish (Chimaera monstrosa), the velvet-belly lanternshark (Etmopterus spinax), and the blackmouth catshark (Galeus melastomus). Focusing on the northern fringe of their distribution, 26 years (1995-2020) of standardised data from Norwegian scientific bottom trawl surveys were analysed using generalized additive models and GIS-based spatial mapping. The results indicate that all three species have undergone significant northward shifts in abundance over the past two decades, although the magnitude and rate varied among species. Several of their prey species exhibited similar latitudinal shifts, suggesting a potential trophic linkage in response to changing thermal regimes. These findings support the hypothesis that warming waters in northern latitudes are driving the poleward redistribution of deep-water chondrichthyans as they seek to remain within their thermal preference ranges. Understanding these spatial responses is critical for informing conservation strategies and future fisheries management in rapidly changing high-latitude marine ecosystems.

Marine crustacean capture fisheries have been contributing increasingly to global aquatic food production in recent decades, helping secure socioeconomic benefits. During 2000–2022 the total landings of marine crustaceans rose by 6.7

In mammals, the calcium-sensing receptor (CaSR) is involved in nutrient sensing and modulated by several amino acids. In teleosts, sequence homologues of the mammalian CaSR have been described but their function in sensing amino acids remains elusive, including in Atlantic salmon (Salmo salar), an important aquaculture species. This study investigated the activation of Atlantic salmon Casr (asCasr)-mediated signaling pathways—Gq, Gi, and ERK1/2—by six selected L-amino acids (histidine, tryptophan, phenylalanine, isoleucine, leucine and valine) and by Ca2+. Using a Flp-In-HEK293 cell line stably expressing asCasr, we confirmed activation of all three pathways. L-histidine, L-phenylalanine, and L-tryptophan triggered Gi signaling independent of Ca²⁺. Notably, no Ca²⁺ concentrations induced Gi activation, but IP1 production increased in a concentration-dependent manner. L-histidine was the only amino acid to activate the Gq pathway without Ca²⁺, and this response was amplified by the presence of Ca²⁺. In the presence of 2.5 mM Ca²⁺, L-phenylalanine and L-tryptophan also activated Gq signaling in a concentration-dependent manner. Additionally, in the presence of 10 mM Ca²⁺, L-histidine, L-phenylalanine, and L-tryptophan triggered ERK phosphorylation. These findings establish asCasr as a functional homologue of mammalian CaSR, activated in a concentration-dependent manner by L-amino acids with an aromatic ring.

Marine recreational fishing (MRF) is a popular outdoor activity that contributes substantially to total harvest in many coastal stocks, yet it is rarely integrated into stock assessments and its impact on target stocks is often unknown. For the red-listed European lobster (Homarus gammarus) in Norway, we applied two probabilistic off-site survey methods (diary and recall) to estimate participation, effort, harvest rates and total harvest across regions. The effects of accounting for MRF were then evaluated in a stock assessment model. The recall method achieved higher response rates and resulted in slightly lower harvest estimates than the diary survey. When combined with a mandatory national registration system, these methods enabled cost-efficient and representative estimation of total harvest. Recreational fishers accounted for 71–90

Marine community sensitivity to climate change can be informed by examining community patterns along current environmental gradients. Fjords provide natural laboratories for such studies due to their variable oceanographic conditions that can differ from basin to basin. Bottom trawl samples were collected from 17 fjord basins and nearshore coastal stations (59–63°N) from 2011 to 2022. We examined how climate‐responsive (temperature, salinity, and oxygen) and fixed environmental variables (bottom depth, sill depth, and distance to coastline) as well as aquaculture impact score (calculated using biomass capacity within a 5 km radius) correlate with differences in hyperbenthic community biomass, diversity, and composition. We focused on fish and crustacean species composition, diversity, and biomass as well as the biomass and distribution of a recently proliferating jellyfish, Periphylla periphylla . Our results indicate that fixed environmental variables (e.g., bottom depth and sill depth) are important predictors of community biodiversity; biodiversity decreased with bottom depth and was highest in fjord basins with 151–250 m deep sills. Fish and crustacean biomass was negatively correlated with distance to coastline. Four community‐types were identified which separated mainly by depth, geographic location (fjord or coastal), and presence of P. periphylla . We found limited evidence of climate‐responsive or aquaculture‐associated drivers being strong predictors of hyperbenthic community differences. The exception was that P. periphylla biomass was negatively correlated with temperature. Oxygen was not a significant predictor of any community patterns. Since West‐Norwegian fjord species are common to the N. Atlantic, the study offers broader insights into community sensitivity to environmental change.

Marine crustacean capture fisheries have been contributing increasingly more to global aquatic food production in recent decades, helping secure socioeconomic benefits. In the past decade the landings of marine crustaceans rose by more than 67% while expanding spatially and taxonomically, doubling their contribution to global fisheries landings. Although efforts to improve the data collection that informs stock assessments and management decisions have risen to promote sustainability of these fisheries, many stocks remain data-limited and unassessed. For many assessed stocks fishing pressures have declined, but some continue experiencing excessive fishing pressures and remain depleted. Here we review recent progress made to stock assessment methods and management measures applied to both data-limited and -rich crustacean stocks across the globe with particular emphasis on addressing sources of uncertainty. Although an increasing number of assessment methods have been developed to account for various types of uncertainty, evaluation of these methods applied to crustaceans is still limited. Less than one-fifth of the recent assessments accounted for multiple types of uncertainty using flexible methods like integrated population models. And uncertainties associated with crustaceans’ unique biology were not fully accounted for in estimating key demographic parameters in many assessments. Our review also identifies areas of research to address remaining knowledge gaps, including parameter estimation uncertainties associated with spatial stock structure, incorporating dynamic ecosystem effects, and management implications of accounting for uncertainties. These issues are anticipated to play a greater role in the performance of assessment methods adopted for and thus the management of crustacean fisheries under ongoing environmental change.

Freshwater rearing conditions influence the growth and seawater adaptation of Atlantic salmon, and swimming exercise may enhance these adaptive processes. This study examined growth and physiological responses of Atlantic salmon subjected to continuous swimming at three speeds: low (0.5 body length per second, BL/s) and moderate (1.0 and 1.5 BL/s) for 11 weeks in freshwater, followed by transfer to brackish water. Fish trained at 1.0 and 1.5 BL/s demonstrated significantly higher specific growth rates and plasma insulin-like growth factor 1 levels after 5 weeks in brackish water, suggesting that moderate exercise enhances growth. Additionally, the 1.5 BL/s group showed a higher frequency of small-diameter white muscle fibers, suggesting hyperplastic growth. Although the expression of growth-related genes was not affected by swimming speed, moderate exercise groups had significantly lower plasma triglycerides and cholesterol levels, suggesting a shift of energy allocation towards growth. At the end of the freshwater phase, distinct energy allocation strategies were evident: the low-speed swimming group had higher hepatosomatic index and plasma inorganic phosphate levels, whereas the 1.5 BL/ s group showed higher muscle adenylate energy charge, indicating enhanced muscle energy status. Fish in moderate swimming groups also had lower cortisol, creatinine (significantly different between 0.5 and 1.5 BL/s), and lactate levels (significantly different between 0.5 and 1.0 BL/s), suggesting an improved stress profile. Swimming exercise did not affect smoltification markers, including NKA activity or plasma sodium and chloride concentrations. Overall, moderate swimming (1.0-1.5 BL/s) improved growth in Atlantic salmon, highlighting potential applications for aquaculture.

To organize microtubules, cells tightly control the activity of the microtubule nucleator γ-tubulin ring complex (γTuRC). The open ring-shaped γTuRC was proposed to nucleate microtubules by a template mechanism. However, its splayed structure does not match microtubule symmetry, leaving it unclear how γTuRC becomes an efficient nucleator. Here, we identify the mechanism of γTuRC activation by CDK5RAP2 centrosomin motif 1 (CM1). Using cryoelectron microscopy (cryo-EM), we find that activation involves binding of multiple CM1 dimers to five distinct sites around the outside of the γTuRC cone, which crucially depends on regulatory modules formed by MZT2 and the N-terminal extensions of GCP2 subunits. CM1 binding promotes lateral interactions between GCP subunits to facilitate microtubule-like conformations and release of luminal actin that is integral to non-activated γTuRC. We propose a model where generation of γTuRC with an expanded conformational range, rather than perfect symmetry, is sufficient to boost nucleation activity.

Spatio-temporal models are essential tools for estimating abundance indices and quantifying the associated uncertainty. Time series of index uncertainties can be used to objectively determine the influence each index has on the assessment. This can involve reducing the influence of indices in years with limited data. However, incorporating uncertainty in age-length conversion into assessment models has remained a challenge. In this research, we propose an index estimation approach that combines an abundance-at-length model with a model for age-at-length to generate age-specific abundance indices. By jointly modeling abundance-at-length and age-at-length, we address uncertainties in both components of the index-at-age. Using North East Arctic haddock (Melanogrammus aeglefinus) as a case study, we validate the uncertainty of the indices by integrating them into the state space assessment model SAM. The results indicate that the uncertainty estimates are realistic, and we further demonstrate that incorporating uncertainty in age conversion has effects on the assessment results. Our case study demonstrates that incorporating the uncertainty in age-at-length data improves the characterization of uncertainty in stock assessment, and hence better accounts for risk in precautionary management.

Predator-prey interactions in time and space determine stock productivity, making them an important consideration when managing marine resources, rebuilding stocks or considering reopening a fishery. We analysed fine-scale diet data from surveys conducted in 2009-2010 and 2018-2019 in three fjords in northern Norway with geostatistical models investigating how predation varied in space, time and between predator species. Our focus prey species was northern shrimp (Pandalus borealis), valuable both as a commercial resource and a major food source for other important species like Atlantic cod (Gadus morhua). Diet composition of fish predators differed clearly between fjords. While predator species and size were good predictors of shrimp predation, the relationships with bathymetry, prey density and geospatial variables were complex. Our study indicates that predation of forage species, such as shrimp, varies spatially in heterogenous fjord ecosystems. Shrimp consumption was not highest in the fjord with highest predator density, indicating a higher dependency of cod on shrimp in specific areas. Realized predation is a complex combination of predator and prey densities and predator ecology that differed in each of the three fjords. Synthesis and applications. Ignoring spatial variations in predator-prey interactions may lead to an inaccurate perception of stock productivity, suboptimal management and possibly unsustainable management targets. We recommend spatially explicit assessment and management for fish stocks where predator-prey interactions vary substantially in space, such as fjords and reefs. Rovdyr-byttedyr-interaksjoner i tid og rom bestemmer produktiviteten til bestander. Det er derfor viktig a ta hensyn til dette i forvaltningen av marine ressurser, gjenoppbygging av bestander eller nar det vurderes a gjenapne et fiske. Vi analyserte finskala diettdata fra bunntraltokt utfort i 2009-2010 og 2018-2019 i tre fjorder i Nord-Norge med geostatistiske modeller, der vi undersokte hvordan predasjon varierte i rom, tid og mellom rovdyrarter. Vi fokuserte pa byttedyret dypvannsreke (Pandalus borealis), som bade er en verdifull kommersiell ressurs og et viktig bytte for andre viktige arter som atlantisk torsk (Gadus morhua). Det var en klar forskjell mellom fjordene i diettsammensetningen til rovfiskene. Mens arter av fisk og storrelsen pa dem var gode predikatorer for rekepredasjon, var sammenhengen med batymetri, byttedyrtetthet og romlige variabler komplekse. Studien var indikerer at predasjon pa typiske byttedyrarter, som reker, varierer romlig i heterogene fjordokosystemer. Rekekonsumet var ikke hoyest i fjorden med hoyest predatortetthet, noe som indikerer at torsk er mer avhengig av reker i bestemte omrader. Realisert predasjon bestar av en kompleks kombinasjon av rovdyr- og byttedyrtettheter og rovdyrokologi, som var forskjellig i hver av de tre fjordene. Syntese og applikasjoner. angstrom ignorere romlige variasjoner i interaksjoner mellom rovdyr og byttedyr kan fore til en unoyaktig forstaelse av bestandsproduktivitet, suboptimal forvaltning og muligens ikke-b AE rekraftige forvaltningsmal. Vi anbefaler en romlig eksplisitt bestandsvurdering og forvaltning for fiskebestander hvor interaksjoner mellom rovdyr og byttedyr i hoy grad varierer i rom, som i fjorder og pa rev. Ignoring spatial variations in predator-prey interactions may lead to an inaccurate perception of stock productivity, suboptimal management and possibly unsustainable management targets. We recommend spatially explicit assessment and management for fish stocks where predator-prey interactions vary substantially in space, such as fjords and reefs.image

Marine ecosystems are undergoing life-history adaptations with impacts on productivity, resilience, and economic value due to Fisheries-Induced Evolution (FIE). Long-term and often intense selective commercial harvesting has led to truncations in population structure and evolutionary changes in key life-history traits. However, the consequences for different functional groups have rarely been evaluated, especially in the context of rebuilding depleted marine stocks. This study uses an individual-based eco-genetic modeling approach to investigate the effects of FIE during shifts in fishing intensity. We focus on functional groups of three types of pelagic fish and three types of demersal fish with different life histories in the China Seas, proposing and evaluating two types of evolving trait response indicators to FIE, and assessing the influence of fishing intensity during the population rebuilding phase. Our results indicate that FIE has a more pronounced impact on biomass recovery in demersal fishes compared to pelagic fishes. The recovery time ranges from 10 to 40 years and strongly correlates with length at 50% vulnerability (L50). Reductions in fishing intensity facilitate biomass recovery, particularly in demersal fishes. In conclusion, our study suggests that adopting a management approach tailored to the needs of distinct functional groups is highly beneficial for promoting the efficient recovery of declining demersal fisheries. This understanding is crucial for developing effective fishery management strategies that integrate the evolutionary responses of different functional groups.

The activity of dynein is regulated by a number of adaptors that mediate its interaction with dynactin, effectively activating the motor complex while also connecting it to different cargos. The regulation of adaptors is consequently central to dynein physiology but remains largely unexplored. We now describe that one of the best-known dynein adaptors, BICD2, is effectively activated through phosphorylation. In G2, phosphorylation of BICD2 by CDK1 promotes its interaction with PLK1. In turn, PLK1 phosphorylation of a single residue in the N-terminus of BICD2 results in a structural change that facilitates the interaction with dynein and dynactin, allowing the formation of active motor complexes. Moreover, modified BICD2 preferentially interacts with the nucleoporin RanBP2 once RanBP2 has been phosphorylated by CDK1. BICD2 phosphorylation is central for dynein recruitment to the nuclear envelope, centrosome tethering to the nucleus and centrosome separation in the G2 and M phases of the cell cycle. This work reveals adaptor activation through phosphorylation as crucial for the spatiotemporal regulation of dynein activity.

The spatial complexity of coastal ecosystems represents a challenge for the management of inshore resources. Here we compared two large fjord systems in northern Norway that have been closed for all bottom trawling for 50 years to a fjord with continuous shrimp fishery with bottom trawls. No significant differences were found between fjords with and without commercial trawling in population density and stock composition of northern shrimp (Pandalus borealis) and their main predator, Atlantic cod (Gadus morhua). Shrimp density was instead linked with bottom depth, while shrimp size and stage composition as well as cod density were explained by seasonal effects and shrimp density. For shrimp, a large degree of the observed variation was captured by spatial correlation that could not be explained by other covariates. The results underline the complex ecology in heavily structured coastal habitats and indicate that coastal shrimp dynamics are shaped by an interplay of multiple ecological and environmental drivers, possibly in concert with local genetic adaptations. The substantial fine-scale spatial variation adds to the challenges of assessing and managing fisheries resources in these fjord ecosystems. Because shrimp are an important forage species, notably as prey for cod, there are potential management conflicts between rebuilding cod stocks and reopening closed shrimp trawling areas.

Precision feeding aims to provide the correct amount of feed to farmed animals for optimal growth and performance and to avoid feed waste. However, knowledge underlying the meal-to-meal variability in voluntary feed intake of farmed species is still limited. This study examined the relationship between meals, feed deprivation time and the feed (pellets) consumed by Atlantic salmon post smolts. The data was collected from individual fish handfed to satiety without social interaction in three independent short-term (6-12 days) experiments. The fixed variables of our model (feed deprivation time (i.e., time between meals), number of pellets provided, day, previous meal size, and fish growth) explained most of the feed intake (number of pellets ingested) (R2 0.68). Results show that fish ingested more pellets over the course of the trials as they grew, resulting in a positive correlation between feed intake and fish growth (final minus initial fish weight). The time between meals and prior meal size (the number of pellets ingested in the previous meal) significantly affected feed intake in the following meal. Our results suggest that it is possible to optimise meal size by considering the size of the previous meal and the time since it was given.

Fisheries management typically considers short planning horizons that stand in contrast to long-term sustainability and biodiversity targets, especially when evolutionary timescales play a role. Many fish stocks globally have been exploited above sustainable levels, causing fisheries-induced evolution towards smaller maturation sizes, lower growth rates and lower economic value of individual fish. Here we couple economic decision-making with eco-evolutionary fish population dynamics to explore (1) the impact of alternative planning horizons in profit-maximizing fisheries management on evolution and (2) the trade-off between profit and a set conservation target. We find that evolutionary decline is reversed only under century-long planning horizons. With more typical short-term planning, stock recovery in terms of biomass is achieved, but evolutionary decline continues, albeit at much lower rates. Setting conservation targets for genetic traits only slightly reduces profits, and the trade-off is further alleviated if the fishery can select for genotypes and thereby assist evolutionary reversal. Sustainability goals and biodiversity targets call for restoring not only fish stocks but also their genetic diversity, implying the reversal of fisheries-induced evolution. We show that economic incentives alone may not be sufficient to achieve these sustainability goals.

Reliable stock assessments are essential for successful and sustainable fisheries management. Advanced stock assessment methods are expensive, as they require age- or length-structured catch and detailed fishery-independent data, which prevents their widespread use, especially in developing regions. Furthermore, modern fisheries management increasingly includes socio-economic considerations. Integrated ecological-economic advice can be provided by bio-economic models, but this requires the estimation of economic parameters. To improve accuracy of data-limited stock assessment while jointly estimating biological and economic parameters, we propose to use price data, in addition to catches, in a new bio-economic stock assessment ('BESA') approach for de-facto open access stocks. Price data are widely available, also in the Global South. BESA is based on a state-space approach and uncovers biomass dynamics by use of the extended Kalman filter in combination with Bayesian estimation. We show that estimates for biological and economic parameters can be obtained jointly, with reliability gains for the stock assessment from the additional information inherent in price data, compared to alternative assessment methods for data-poor stocks. In a real-world application to Barents Sea shrimp (Pandalus borealis, Pandalidae), we show that BESA benchmarks well also against advanced stock assessment results. BESA can thus be both a stand-alone approach for currently unassessed stocks as well as a complement to other available methods by providing bio-economic information for advanced fisheries management.

Recreational and semi-subsistence fisheries are challenging to monitor but can act as precursors of developments in commercial fisheries, contributing information in data-limited situations. We compared trends in commercial landings of Norway lobster (Nephrops norvegicus) with data collected through a citizen science project by recreational fishers in Norway during a period that coincided with the onset of a commercial trap fishery. The results show that trap fishing for Nephrops emerged recently in Norway, with significant regional differences in size composition and catch rates. Comparable patterns in catch rates between regions were found in commercial landings during the same period, suggesting that landings per boat trip may provide a suitable abundance index in a severely data-limited fishery. Our study indicates that recreational fishing acted as trailblazer for a surge in fishing with lower-impact gear along the Norwegian coast, underscoring the fact that non-commercial fisheries may act as early indicators of emerging commercial fisheries. Collecting information through citizen science projects targeting non-commercial fishers can therefore provide baseline data, especially from the earliest, unmonitored stages of fisheries, and contribute to stock assessment.

Impacts of climate change on ocean productivity sustaining world fisheries are predominantly negative but vary greatly among regions. We assessed how 39 fisheries resources-ranging from data-poor to data-rich stocks-in the North East Atlantic are most likely affected under the intermediate climate emission scenario RCP4.5 towards 2050. This region is one of the most productive waters in the world but subjected to pronounced climate change, especially in the northernmost part. In this climate impact assessment, we applied a hybrid solution combining expert opinions (scorings)-supported by an extensive literature review-with mechanistic approaches, considering stocks in three different large marine ecosystems, the North, Norwegian and Barents Seas. This approach enabled calculation of the directional effect as a function of climate exposure and sensitivity attributes (life-history schedules), focusing on local stocks (conspecifics) across latitudes rather than the species in general. The resulting synopsis (50-82 degrees N) contributes substantially to global assessments of major fisheries (FAO, The State of World Fisheries and Aquaculture, 2020), complementing related studies off northeast United States (35-45 degrees N) (Hare et al., PLoS One, 2016, 11, e0146756) and Portugal (37-42 degrees N) (Bueno-Pardo et al., Scientific Reports, 2021, 11, 2958). Contrary to prevailing fisheries forecasts elsewhere, we found that most assessed stocks respond positively. However, the underlying, extensive environmental clines implied that North East Atlantic stocks will develop entirely different depending upon the encountered stressors: cold-temperate stocks at the southern and Arctic stocks at the northern fringes appeared severely negatively impacted, whereas warm-temperate stocks expanding from south were found to do well along with cold-temperate stocks currently inhabiting below-optimal temperatures in the northern subregion.

Growth is a key component of population dynamics and, thus, fisheries management, yet drivers of its variations are often poorly understood. Using individual data collected over 80 years, we explored how environmental drivers affect growth in a major population of Atlantic herring (Clupea harengus). The results confirm that intrinsic factors (age and maturation) determine growth to a large degree but also that extrinsic factors such as temperature have some influence. While the role of intrinsic factors was independent of time series length, the importance of extrinsic drivers varies strongly with the analysed time period. It remains unclear whether this is caused by data inconsistencies back in time, spurious correlations appearing in shorter time series, shifts in population dynamics, or dynamic interactions between variables that cannot be determined with current data. Generally, environmental effects on growth became less clear and relevant with increasing time series length. What drives variation in growth may therefore change over time, potentially due to impacts such as fishing or climate change. It also underlines that seemingly clear correlations can break down or change their sign over time; hence, caution is advised when interpreting results from time series of 20–40 years.