The target species (Aphia minuta and Pseudaphya ferreri) of the transparent goby fishery on Mallorca Island (Balearic Islands, western Mediterranean) are currently discarded when the maximum daily ...catch is exceeded or when the sorting process is unworkable. The mortality suffered by this discarded fraction remains unknown, although it may be important for resource management. Accordingly, the aims of this study were to (1) assess the environmental drivers of the relative post-release survival of the discarded target species and (2) test the correlations between post-release survival and two behavior-related variables (swimming speed and its increase after a stimulus, assessed via video recording). To do so, mortality of the target species from 47 hauls sampled under normal fishing boat operations was monitored when the gear was onboard and after a few hours. At the reference level (an average depth of 25.7 m and temperature of 15.7 ºC), the immediate survival was 99.9% (95% CI: 97.9 to 100%), but the estimated post-release survival decreased to 47.2% (33.8 to 65.8%). Relative post-release mortality doubled when the water temperature increased by 2.8 ºC or when the fishing depth increased up to 32 m. Furthermore, the swimming speed of the target species was significantly correlated with the estimated post-release survival; thus, this vitality metric may offer a promising strategy for more easily estimating post-release mortality in other fisheries.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Most reintroduction and restocking programs consist of releasing captive-raised juveniles. The usefulness of these programs has been questioned, and therefore, quality control is advisable. However, ...evaluating restocking effectiveness is challenging because mortality estimation is required. Most methods for estimating mortality are based on tag recovery. In the case of fish, juveniles are tagged before release, and fishermen typically recover tags when fish are captured. The statistical models currently available for analyzing these data assume either constant mortality rates, fixed tag non-reporting rates, or both. Here, instead, we proposed a method that considers the mortality rate variability as a function of age/size of the released juveniles. Furthermore, the proposed method can disentangle natural from fishing mortality, analyzing the temporal distribution of the captures reported by fishermen from multiple release events. This method is demonstrated with a restocking program of a top-predator marine fish, the meagre (Argyrosomus regius), in the Balearic Islands. The estimated natural mortality just after release was very high for young fish (m0 = 0.126 day-1 for fish 180 days old), but it was close to zero for large/old fish. These large/old fish were more resilient to wild conditions, although a long time was needed to achieve a relevant reduction in natural mortality. Conversely, these large/old fish were more vulnerable to fishing, creating a trade-off in survival. The release age that maximizes the number of survivors after, for example, one year at liberty was estimated to be 1,173 days. However, the production cost of relatively old fish is high, and only a few fish can be produced and released within a realistic budget. Therefore, in the case of the meagre, increasing the number of released fish will have no or scarce effects on restocking success. Conversely, it is advisable implement measures to reduce the high natural mortality of young juveniles and/or the length of time needed to improve fish resilience.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The effect of serine/threonine-protein kinase B-Raf/mitogen-activated protein kinase (BRAF/MEK) inhibitors on the immune system is not clearly described, but rare cases of autoimmune phenomena have ...been reported. The clinical case we present below is the first report of a necrotizing myopathy related to dabrafenib/trametinib treatment. A 48-year-old man started dabrafenib/trametinib for stage IV BRAF-V600E mutated cutaneous melanoma. After the first month, he presented with grade 3 pyrexia (Common Terminology Criteria for Adverse Events CTCAE v.5.0.) and increased creatinine-kinase levels. A diagnosis of immune-mediated necrotizing myopathy, antisignal recognition particle (anit-SRP) positive, was made. At disease progression, dabrafenib/trametinib was restarted, triggering a new episode of grade 2 pyrexia and myositis. Treatment was changed to encorafenib/binimetinib without repeating pyrexia or limiting creatinine-kinase elevation, presenting even a loss of anti-SRP antibodies. Given the temporal relationship, the fact that re-exposition induced a new worsening of the myopathy and the loss of the anti-SRP antibodies after changing treatment, we infer that there possibly is a clear relationship between dabrafenib/trametinib treatment and the myopathy.
Effective fisheries management needs to consider spatial behavior in addition to more traditional aspects of population dynamics. Acoustic telemetry has been extensively used to provide information ...on fish movements over different temporal and spatial scales. Here, we used a fixed-receiver array to examine the movement patterns of Labrus bergylta Ascanius 1767, a species highly targeted by the artisanal fleet of Galicia, NW Spain. Data from 25 individuals was assessed for a period of 71days between September and November 2011 in the Galician Atlantic Islands Maritime-Terrestrial National Park. Fish were present within the monitored area more than 92% of the monitored time. The estimated size of individual home ranges, i.e. the area where fish spent most of their time, was small. The total minimum convex polygons area based on all the estimated positions was 0.133±0.072km2, whereas the home range size estimated using a 95% kernel distribution of the estimated positions was 0.091±0.031km2. The core area (50% kernel) was 0.019±0.006km2. L. bergylta exhibited different patterns of movement in the day versus the night, with 92% of the fish detected more frequently and traveling longer distances during the daytime. In addition, 76% of the fish displayed a larger home range during the day versus during the night. The linearity index was less than 0.005 for all fish suggesting random movements but within a relatively small area, and the volume of intersection index between consecutive daily home ranges was 0.75±0.13, suggesting high site fidelity. The small home range and the sedentary behavior of L. bergylta highlight the potential use of small MPAs as a management tool to ensure a sustainable fishery for this important species.
•We investigated the spatio-temporal behavior of Labrus bergylta.•Labrus bergylta exhibited high residency over the 71 days of the study period.•Clear diel behavior inside a small home range has been recorded.•Marine protected areas can offer long-term protection for this species.
The cuttlefish (Sepia officinalis) trammel net fishery is one of the most important small-scale fisheries in the Mediterranean Sea. Here we describe the main catch, by-catch and discard patterns ...found in this fishery on Mallorca Island by onboard surveys of 1005 netting walls from 23 fishing trips. The number of items captured, their size and their subsequent use, i.e. kept for sale or discarded, were recorded. Furthermore, the immediate survival of the unwanted items (i.e. vitality state when the gear came on board) and the medium-term survival of a subsample were assessed. The cuttlefish was the dominant species in the commercial fraction of the catch, particularly during the fishing season peak (March). However, S. officinalis catches quickly decreased further into the season, with other high-value fish, such as Scorpaena scrofa, increasing in the commercial fraction of the catch. As species composition is continuously changing, it is often difficult to determine the main target species of this fishery. This strategy possibly complicates management but maximizes fishing revenue, which was an average of €175 per trip. With respect to discards, up to 104 different species were caught but not commercialized. The most abundant were Holothuria sp. and Torpedo marmorata. Their immediate survival was 100% and 20%, respectively. In both cases, the medium-term survival and the vitality status were high after seven days in monitored captivity. Therefore, in these cases, their immediate release to the sea should be promoted, given that they are exempt from the EU landing obligation. Interviews with fishers revealed that the perceived quantity of discards was lower than the amount recorded by the present study. Currently, just a small percentage (1.5%) of these discards will be affected by the landing obligation enforced by the new European discards ban.
Acoustic telemetry techniques are very useful tools to monitor in detail the swimming behaviour and spatial use of fish in artificial rearing environments at individual and group levels. We evaluated ...the feasibility of using passive acoustic telemetry to monitor fish welfare in sea-cage aquaculture at an industrial scale, characterizing for the first time the diel swimming and distribution patterns of gilthead seabream (Sparus aurata) at fine-scale. Ten fish were implanted with acoustic tags equipped with pressure and acceleration sensors, and monitored in a commercial-size sea-cage for a period of one month. Overall, fish exhibited clear differences in day vs night patterns both on swimming activity and vertical distribution throughout the experiment. Space use increased at night after the implementation of structural environmental enrichment in the sea-cage. Acoustic telemetry may represent an advancement to monitor fish farming procedures and conditions, helping to promote fish welfare and product quality.
With the advent of deep-learning (DL) techniques, image annotation has become a fundamental part of the research process. In the case of underwater image annotation, the human in charge of the task ...is faced whith the inherent quality problems of this kind of images. A large number of underwater image enhancement (UIE) methods have been developed aimed at improving the colors and contrast of these images. However, no attention has been paid to the specific problem of image annotation. In this case the global image quality of the processed image is less important than the fact that the objects to be annotated stand out and that their contours are easy to delineate. In this paper we evaluate seven state-of-the-art UIE techniques and rank them, through a subjective approach, according to their utility for the annotation process. The conclusion of our study is that, in general, the model-free Multiscale Retinex algorithm is preferred over more complex techniques that try to model the formation of the underwater images.
Further investigation is needed to improve the identification and classification of fish in underwater images using artificial intelligence, specifically deep learning. Questions that need to be ...explored include the importance of using diverse backgrounds, the effect of (not) labeling small fish on precision, the number of images needed for successful classification, and whether they should be randomly selected. To address these questions, a new labeled dataset was created with over 18,400 recorded Mediterranean fish from 20 species from over 1,600 underwater images with different backgrounds. Two state-of-the-art object detectors/classifiers, YOLOv5m and Faster RCNN, were compared for the detection of the ‘fish’ category in different datasets. YOLOv5m performed better and was thus selected for classifying an increasing number of species in six combinations of labeled datasets varying in background types, balanced or unbalanced number of fishes per background, number of labeled fish, and quality of labeling. Results showed that i) it is cost-efficient to work with a reduced labeled set (a few hundred labeled objects per category) if images are carefully selected, ii) the usefulness of the trained model for classifying unseen datasets improves with the use of different backgrounds in the training dataset, and iii) avoiding training with low-quality labels (e.g., small relative size or incomplete silhouettes) yields better classification metrics. These results and dataset will help select and label images in the most effective way to improve the use of deep learning in studying underwater organisms.
In the Balearic Islands, different trammel net designs have been adopted to promote fisheries sustainability and reduce discards. Here, we compare the catch performance of three trammel net designs ...targeting the spiny lobster
in terms of biomass, species composition and revenue from commercial catches and discards. Designs differ in the netting fiber type (standard polyfilament, PMF, or a new polyethylene multi-monofilament, MMF) and the use of a guarding net or
, a mesh piece intended to reduce discards. Catches were surveyed by an on-board observer from 1,550 netting walls corresponding to 70 nets. The number of marketable species captured indicated that the lobster trammel net fishery has multiple targets, which contribute significantly to the total revenue. The discarded species ranged from habitat-forming species to elasmobranches, but the magnitude of gear-habitat interactions on the long term dynamics of benthos remains unclear. No relevant differences in revenue and weight of discards were detected after Bayesian analyses. However, the species composition of discards was different when using
. Interestingly, high immediate survival was found for discarded undersized lobsters, while a seven day survival assessment, using captive observation, gave an asymptotic estimate of survival probability as 0.64 (95% CI 0.54-0.76). Therefore, it is recommended that it would be beneficial for this stock if an exemption from the EU landing obligation regulation was sought for undersized lobsters in the Balearic trammel net fishery.
The abundance, nature and possible sources of litter on 32 beaches on the Balearic Islands (Mediterranean Sea) were investigated in 2005. Mean summer abundances in the Balearics reached approximately ...36 items m super(-1), with a corresponding weight of 32 plus or minus 25 g m super(-1), which is comparable to the results of other studies in the Mediterranean. Multivariate analyses (principal component analysis and redundancy analysis) confirmed strong similarities between islands and a statistically significant seasonal evolution of litter composition and abundance. In summer (the high tourist season), debris contamination expressed as item abundance was double that in the low season and showed a heterogeneous nature associated with beach use. Cigarette butts were the most abundant item, accounting for up to 46% of the objects observed in the high tourist season. In contrast, plastics related to personal hygiene/medical items were predominant in wintertime (67%) and natural wood was the most important debris by weight (75%). In both seasons, litter characteristics suggested a strong relationship with local land-based origins. While beach users were the main source of summer debris, low tourist season litter was primarily attributed to drainage and outfall systems.
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