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Defensive chemicals are used by plants and animals to reduce the risk of predation through different mechanisms, including toxins that cause injury and harm (weapons) and unpalatable or odiferous compounds that prevent attacks (deterrents). However, whether effective defences are both toxins and deterrents, or work in just one modality is often unclear. In this study, our primary aim was to determine whether defensive compounds stored by nudibranch molluscs acted as weapons (in terms of being toxic), deterrents (in terms of being distasteful), or both. Our secondary aim was to investigate the response of different taxa to these defensive compounds. To do this, we identified secondary metabolites in 30 species of nudibranch molluscs and investigated their deterrent properties using anti-feedant assays with three taxa: rock pool shrimp, Palaemon serenus, and two fish species: triggerfish Rhinecanthus aculeatus and toadfish Tetractenos hamiltoni. We compared these results to toxicity assays using brine shrimp Artemia sp. and previously published toxicity data with a damselfish Chromis viridis. Overall, we found no clear relationship between palatability and toxicity, but instead classified defensive compounds into the following categories: Class I & II - highly unpalatable and highly toxic; Class I - weakly unpalatable and highly toxic; Class II - highly unpalatable but weakly toxic; WR (weak response) - weakly unpalatable and weakly toxic. We also found eight extracts from six species that did not display activity in any assays indicating they may have very limited chemical defensive mechanisms (NR, no response). We found that the different classes of secondary metabolites were similarly unpalatable to fish and shrimp, except extracts from Phyllidiidae nudibranchs (isonitriles) that were highly unpalatable to shrimp but weakly unpalatable to fish. Our results pave the way toward better understanding how animal chemical defences work against a variety of predators. We highlight the need to disentangle weapons and deterrents in future work on anti-predator defences to better understand the foraging decisions faced by predators, the resultant selection pressures imposed on prey, and the evolution of different anti-predator strategies.

The feeding habits and reproductive biology of red-toothed triggerfish Odonus niger (Ruppell, 1836) was analysed from 449 specimens collected from the Karnataka coast of the south-eastern Arabian Sea. Of the total stomachs examined, only 54 (12%) were empty and 395 contained food remains. The diet comprised crustacean remains (48.0%), zooplankton (21.4%), algae (16.5%), fish remains (6.1%) and cephalopod remains (5.3%) along with partially digested matter (2.3%) and detritus (0.4%). The species was found to be a generalist feeder and an omnivore. The overall sex ratio between males and females (1: 0.44) was significantly (P < 0.05) different. Histological examination of the ovaries indicated asynchronous ovarian development in females, with males maturing earlier than females. The gonadosomatic index (GSI) patterns of males and females, and the presence of ripe ovaries and spermatozoids suggested that April–May is the peak spawning period. The absolute and relative fecundity estimates ranged from 16,464–312,420 eggs and 251–2812 eggs g−1 respectively. Fecundity was positively correlated with total length and body weight. The biological information on diet composition and reproductive traits provided for the first time in this study can facilitate conservation, management and sustainable exploitation of this species in the study area.

Nile tilapia is a freshwater fish that is widely cultivated in Indonesia. During its development, tilapia aquaculture has constraints such as low growth rates. Therefore, it is necessary to add a feed additive to the feed in the form of charcoal. Charcoal is an adsorbent that has high absorption so that the addition of charcoal in the feed can increase the absorption of nutrients of tilapia. A 45-days trial was conducted to determine the percentage of addition of triggerfish bone charcoal (Abalistes stellaris) as a feed supplement that affect the growth performance and intestines of tilapia. The research design was a non-factorial Completely Randomized Design (CRD) with 4 treatments and 2 replications as treatments including: treatment A (control), B (addition of 1%charcoal), C (addition of 2% charcoal) and D (addition of 3% charcoal). A total of 240 tilapia fingerlings (5-7 cm) were used and placed in 8 aquariums then filled with 72 liters of water. Providing adlibitum (unlimited) feed with a frequency of 2 times a day. The ANOVA test showed that the addition of triggerfish bone charcoal (A. stellaris) in the feed was not significantly different (P > 0.05) in weight growth, absolute length and daily length growth but it was significantly different (P < 0.05) in feed conversion ratio and the efficiency of feed utilization. Based on result, it was concluded that the addition of 3% charcoal was the best treatment which gave the lengthiest of villi which was increasing the length of the intestinal villi to 71.11 µm from the initial length of 162.22 µm. easel at 233.33 μm, showed the highest feed conversion ratio value and feed efficiency (1.12 %, 89.6%). Keywords: Charcoal Fish bone Intestinal histology Starry triggerfish

Quantitative surveys of fishes associated with artificial reefs in the northwest Gulf of Mexico were conducted over a 4-yr period (2014–2017). Artificial reefs surveyed were comprised of three types: concrete structures, rig jackets, and decommissioned ships. All reefs were surveyed using vertical long line (VLL), fish traps, and Adaptive Resolution Imaging Sonar (ARIS 1800). Mean fish abundance did not significantly differ using VLL [1.7 ind set –1 (SD 2.2)] among the three reef types. However, relative abundance among all fishes collected was significantly highest on rig reefs using traps [6.2 ind soak–1 (SD 3.8)], while results from sonar surveys indicated that the mean relative fish density was highest on concrete reefs [15.3 fish frame–1 (SD 26.8)]. Red snapper (n = 792), followed by gray triggerfish (n = 130), pigfish (n = 70), tomtate (n = 69), and hardhead catfish (n = 57) were the most numerically abundant species using VLL and traps; red snapper comprised 90.7% of total catch using VLL and 43.9% using traps. Mean Brillouin's diversity (HB) was highest on ships using VLL [0.41 (SD 0.14)] and highest on rigs using traps [0.87 (SD 0.58)] compared to the lowest diversity found on concrete [VLL 0.07 (SD 0.11); traps 0.36 (SD 0.32)]. Findings from this study can be used to inform the planning of future artificial reefs and their effect on the assemblages of reef-associated fishes. Additionally, these results highlight the value of using multiple gear types to survey reef fish assemblages associated with artificial reefs.

Coral reef fishes use a multitude of diverse feeding behaviours to increase their ability to successfully capture a wide range of prey. Here, this study reports a novel hunting behaviour in a coral reef fish, the titan triggerfish, Balistoides viridescens, where an individual was seen partially beaching itself while attempting to catch a Red Sea ghost crab, Ocypode saratan. This is the first report of this behaviour in the order Tetraodontiformes and represents an astonishing capability of this species to exploit food resources outside their typical assumed ecological niche.

Learning outcomes The learning outcomes of this paper are as follows: to critically assess and analyse public and private funding options and determine which private option is best suited to a company (finance – decision-making). To calculate the internal rate of return (IRR) of a project (finance – analytical). To critically assess the underlying structures of traditional and new industries (Strategy/BMI – analytical). To analyse the challenges and disruption potential of intermediated industries (Strategy/BMI – analytical). Case overview/synopsis The Triggerfish case looks at how films are funded in South Africa. The company is currently funding films mostly through government channels, but CEO Stuart Forrest would prefer to independently and privately fund their projects. The case looks at what returns can be expected by investors in film through the “recoupment waterfall” – the means whereby the producers and investors of a film recoup their investments and earn returns. The investment horizons of select private lenders (bank, mezzanine financiers, risk financers and venture capital firms) and public funders are explored. The case also explores the impact that video-on-demand platforms, such as Netflix and Disney+, is having on the traditional models of filmmaking. Complexity academic level This teaching case is aimed at postgraduate business students such as Master’s degrees in Business Administration degrees, postgraduate diplomas, executive education or specialist Master’s degrees. Supplementary materials Teaching notes are available for educators only. Subject code CSS 3: Entrepreneurship.

Estimates of animal abundance are widely used to support conservation and resource management. For populations in open systems, abundance estimates from tagging data can be highly uncertain or biased. Here, we develop a novel approach to estimate abundance of an open population by pairing two models, each utilizing distinct tagging data. Using data from telemetry tags, we infer movement rates to and from the study site with a Markovian model allowing for an environmental effect. Then, using data from conventional passive tags, we apply a Lincoln–Petersen abundance estimator modified to account for mortality and movement. After developing the model within a Bayesian framework, we demonstrate its application to data on gray triggerfish (Balistes capriscus) tagged in the Atlantic Ocean off North Carolina, USA. For this open population, we estimate site abundance to be ∼1000 fish (∼2000 fish·km–2) and additionally find evidence for an effect of hurricanes on movement. The general approach may be useful for fisheries, wildlife, and other ecological studies utilizing multiple tag types, particularly for estimating abundance of an open population.

Habitat heterogeneity shapes biological communities, a well-known process in terrestrial ecosystems but substantially unresolved within coral reef ecosystems. We investigated the extent to which coral richness predicts intra-family fish richness, while simultaneously integrating a striking aspect of reef ecosystems—coral hue. To do so, we quantified the coral richness, coral hue diversity, and species richness within 25 fish families in 74 global ecoregions. We then expanded this to an analysis of all reef fishes (4465 species). Considering coral bleaching as a natural experiment, we subsequently examined hue's contribution to fish communities. Coral species and hue diversity significantly predict each family's fish richness, with the highest correlations (> 80%) occurring in damselfish, butterflyfish, emperors and rabbitfish, lower (60–80%) in substrate-bound and mid-water taxa such as blennies, seahorses, and parrotfish, and lowest (40–60%) in sharks, morays, grunts and triggerfish. The observed trends persisted globally. Coral bleaching's homogenization of reef colouration revealed hue’s contribution to maintaining fish richness, abundance, and recruit survivorship. We propose that each additional coral species and associated hue provide added ecological opportunities (e.g. camouflage, background contrast for intraspecific display), facilitating the evolution and co-existence of diverse fish assemblages.

Background: The aim of the study is to investigate whether the circadian IOP rhythm can be influenced by combined cataract surgery with high frequency deep sclerotomy (HFDS) and whether intraocular pressure (IOP) can be significantly reduced by HFDS. Methods: In our study 10 patients were included, in whom 24 h IOP monitoring was installed before and after HFDS/cataract surgery using a Triggerfish. HFDS is a minimally invasive glaucoma surgery (MIGS). Results: After performed HFDS combined with cataract surgery, the IOP was reduced from 27.7 ± 2.11 mmHg to 14.4 ± 2.59 mmHg, which is highly significant (p &lt, 0.001). The contact lens sensor (CLS) cosinor analysis pre- and postoperatively showed that the circadian rhythm is not influenced by the surgery, i.e., the circadian IOP rhythm did not show significant differences before and after surgery. Conclusions: HFDS combined with cataract surgery is a potent surgical method that can significantly reduce the IOP. However, the circadian rhythm cannot be changed by the surgery. The acrophase remained during the night in all patients.

Coral reef ecosystems are at the forefront of biodiversity loss and climate change-mediated transformations. This is expected to have profound consequences for the functioning of these ecosystems. However, assessments of ecosystem function on reefs are often spatially limited, within biogeographic realms, or rely on presumed proxies such as traits. To address these shortcomings and assess the effects of biogeography and fish presence on the critical ecosystem function of macroalgal removal, we used assays of six algal genera across three reef habitats in two biogeographically distinct locations: Little Cayman in the Caribbean and Lizard Island on the Great Barrier Reef (GBR). Patterns of fish feeding and realised ecosystem function were strikingly similar between the two geographic locations, despite a threefold difference in the local diversity of nominally herbivorous fishes, a 2.4-fold difference in the diversity of fishes feeding and differences in the biogeographic history of the two locations. In both regions, a single species dominated the function: a surgeonfish, Naso unicornis, at the GBR location and, surprisingly, a triggerfish, Melichthys niger, at the Caribbean location. Both species, especially M. niger, were relatively rare, compared to other nominally herbivorous fishes, in censuses covering more than 14,000 m2 at each location. Our study provides novel insights into the critical function of macroalgal removal in hyperdiverse coral reef ecosystems, highlighting: (a) that function can transcend biogeographic, taxonomic and historical constraints; and (b) shortcomings in our assumptions regarding fish presence and realised ecosystem function on coral reefs.

Temperate reef fishes provide many benefits to humans including food, sport, and ecotourism, yet remain severely understudied compared to coral reef fishes in tropical environments. We used 3 years of underwater video data (n = 4130 samples) from hardbottom reefs along the continental shelf of the southeastern US Atlantic coast (i.e., North Carolina to Florida; ~ 100,000 km2) to quantify the spatial and temporal patterns of temperate reef fish biodiversity in the region. Overall, 210 taxa were identified on video from 53 families, 138 of which could be identified to the species level. Species with the highest percent occurrence were gray triggerfish (Balistes capriscus; observed on 45.6% of all videos), tomtate (Haemulon aurolineatum; 42.7%), and red porgy (Pagrus pagrus; 39.4%), and 23 species were observed on more than 10% of videos. Latitudinal variability swamped temporal changes (2015–2017) for most taxa. After accounting for the influence of water clarity and current direction on video detectability, generalized additive models suggested that species and family richness were highest at sites characterized by moderate depths, a high proportion of hardbottom, high substrate relief, and warm water. Our results can be used to predict areas of highest reef fish biodiversity at large (regional) and small (microhabitat) scales to improve marine protected area design, delineate essential fish habitats, and parameterize ecosystem models.

The overexploitation of many traditionally targeted reef fishes, such as red snapper, Lutjanus campechanus (Poey, 1860), alongside the implementation of increasingly restrictive management measures on those species, has led to increased targeting of conventionally discarded Gulf of Mexico gray triggerfish, Balistes capriscus Gmelin, 1789, commercially and recreationally. The goal of this study was to assess age and growth of gray triggerfish from the Alabama Artificial Reef Zone in the north-central Gulf of Mexico. Gray triggerfish (n = 1135) were collected predominantly from artificial habitat during 1999–2017. Specimens were sexed macroscopically and ages were assigned by counting translucent increments in sections of the first dorsal spine. Fish ranged in size from 22 to 617 mm fork length. The oldest female was assigned an age of 9 yrs; the oldest male, 10 yrs. A suite of growth models was tested to develop combined and sex-specific models. The von Bertalanffy growth function best fit the combined data with parameters L∞ = 488.63 (SE 5.19), k = 0.57 (SE 0.02), and t 0= –0.27 (SE 0.03). Mean size-at-age differed between sexes for six of the eight ages which possessed sample sizes large enough to make comparisons. Growth differed between sexes, and the best-fitting version of the von Bertalanffy growth function permitted L∞ to vary by sex [female L∞ = 480.26 (SE 7.99); male L∞ = 532.89 (SE 8.95); k = 0.44 (SE 0.04); t 0 = –0.78 (SE 0.16)]. These findings enhance our knowledge of the age and growth of Gulf of Mexico gray

The article of record as published may be found at https://doi.org/10.1038/s41598-018-37527-1 Extreme weather events strongly influence marine, freshwater, and estuarine ecosystems in myriad ways. We quantified movements of a demersal oceanic fish species (gray triggerfish Balistes capriscus; N = 30) before, during, and after two hurricanes in 2017 using fine-scale acoustic telemetry at a 37-m deep study site in North Carolina, USA. During storms, gray triggerfish movement and emigration rates were 100% and 2550% higher, respectively, than on days with no storms. We found that increased movement rates were much more strongly correlated with wave orbital velocity (i.e., wave-generated oscillatory flow at the seabed) than either barometric pressure or bottom water temperature, two covariates that have been demonstrated to be important for organisms in shallower water. Higher movement rates during storms were due to increased mobility at night, and emigrations typically occurred at night in the direction of deeper water. Overall, we found significant storm effects on the movement behavior of a demersal fish species in the open ocean, despite our study occurring in deeper water than previous studies that have examined storm effects on animal movement. We conclude that tropical storms are a driving force behind the structure of marine ecosystems, in part by influencing movements of mobile animals. Funding was provided by the Marine Fisheries Initiative program of the U.S. National Marine Fisheries Service. Funding was provided by the Marine Fisheries Initiative program of the U.S. National Marine Fisheries Service.

A checklist of the triggerfishes (Pisces: Balistidae) is presented. The list includes: 183 nominal species grouped in 41 valid species belonging to 12 genera; 28 nomina nuda; 8 nominal species which are recognized in this study to belong to a different family of fishes. Some 22 nominal species are in this study regarded as new synonyms.

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.

Overfishing is a key stressor in many coral reefs, affecting their function and ecosystem services. In the Gulf of California, 50 years of artisanal and recreational fishing have removed most of the largest and most vulnerable fish species, the Espiritu Santo Archipelago (ESA) is a marine protected area (MPA) where artisanal and recreational fishing are allowed in most of the natural reefs, while the artificial reefs (wrecks) are fully protected. An important question under such circumstances is whether artificial reefs can serve as surrogate habitats for the natural reefs. To address this question, we characterized the fish community (species richness, abundance, differences in taxonomic structure) and analyzed the obtained data by multivariate ordination and similarity analysis. The highest species richness was found in the artificial reefs, with total of 83 species, of which 21 species were exclusive. Contrary to the species richness, the total fish abundance was 20% higher at the natural reefs. The fish assemblages of the artificial reefs differ significantly from those of the natural reefs. The natural reefs of the ESA are dominated by few fish species from families of lower trophic levels. In contrast, the studied shipwrecks provide refuge to commercially important fish species (such as Snappers, Triggerfish, Jacks, and Groupers) including threatened species. The different fish compositions on the natural and artificial reefs is likely to be the outcome of differential fishing pressure. The non-fished areas (wrecks) of the ESA may represent a good strategy for reef restoration, enhanced fishing grounds (via spillover) and fishing management. However, the fish community structure of the artificial reefs differs from natural rocky reefs of the ESA, and therefore, should not be considered as surrogate habitats for natural reefs. The results point out the need to reassess the management effectiveness of the natural reefs of the ESA.

Three digeneans belonging to the Opecoelidae are reported and described from triggerfishes (Tetraodontiformes: Balistidae) collected in the northern Red Sea off Egypt. Both Macvicaria longicirrata (Manter, 1963) Aken-Ova, Cribb & Bray, 2008 and Neopycnadena tendu (Bray & Justine, 2007) n. comb. were recovered from the intestine of the titan triggerfish, Balistoides viridescens (Bloch & Schneider)—each represents a new host record—and Gaevskajatrema balistes n. sp. was found parasitizing the lower intestine of the Picasso triggerfish, Rhinecanthus assasi (Forsskål). We continue to support synonymy of Gaevskajatrema ponticum (Koval, 1966) Machkevsky, 1990 with Gaevskajatrema perezi (Mathias, 1926) Gibson & Bray, 1982, not as a differentiated species. We adopt the restricted posterior extension of the ceca and vitellarium to the testicular zone, without extension of either into the post-testicular space, as diagnostic in distinguishing Gaevskajatrema. Gaevskajatrema balistes n. sp. differs from G. perezi based on its substantially smaller body size with fewer eggs, a longer cirrus-pouch reaching ovarian level and it parasitizes a distinct host group from a structurally and ecologically different ecosystem. Neopycnadena n. gen. is erected for Pseudopycnadena tendu Bray & Justine 2007 based on its possessing a large broadly oval cirrus-pouch with a massive field of prostatic cells occupying the entire volume of the cirrus-pouch, a wide, cup-shaped and thick-walled ejaculatory duct, distinct dorsal position of the excretory pore, the bifurcal dextral position of the genital pore, its report from a distinct host group and distant locality and its phylogenetic uniqueness compared with Pseudopycnadena fischthali Saad-Fares & Maillard 1986. Neopycnadena n. gen. is ecologically similar to opistholebetines in their life-cycles and morphology; however, phylogenetically separate from opistholebetines as well as from the Polypipapiliotrematinae Martin, Cutmore & Cribb in Martin, Sasal, Cutmore, Ward, Aeby & Cribb, 2018 and members of Clade [C] of Martin and colleagues, thus we conclude that Neopycnadena n. gen. is unique. Neopycnadeninae n. subfam. is proposed to accommodate Neopycnadena n. gen. We consider that the probable characterization of tetraodontiform specialist taxa (as indicated by the presence of a muscular post-oral ring) and the specificity of the Opistholebetinae Fukui, 1929 sensu stricto with a tetraodontiform host are no longer reliable characters differentiating Gaevskajatrema and Macvicaria Gibson & Bray, 1982. The nature of the post-oral structure is discussed and it is adopted to be a diagnostic feature at the generic level among taxa of the Opistholebetinae sensu latu. It is concluded that the expanded concept of the Opistholebetinae is more supported than the restricted one, Birendralebes Srivastava & Ghosh, 1972 remains incertae sedis within the Opecoelidae Ozaki, 1925 rather than in the Opistholebetinae, and we provide a generic key to the Opistholebetinae.

Achromatic (luminance) vision is used by animals to perceive motion, pattern, space and texture. Luminance contrast sensitivity thresholds are often poorly characterised for individual species and are applied across a diverse range of perceptual contexts using over-simplified assumptions of an animal’s visual system. Such thresholds are often estimated using the Receptor Noise Limited model (RNL) using quantum catch values and estimated noise levels of photoreceptors. However, the suitability of the RNL model to describe luminance contrast perception remains poorly tested.Here, we investigated context-dependent luminance discrimination using triggerfish (Rhinecanthus aculeatus)presented with large achromatic stimuli (spots) against uniform achromatic backgrounds of varying absolute and relative contrasts. ‘Dark’ and ‘bright’ spots were presented against relatively dark and bright backgrounds. We found significant differences in luminance discrimination thresholds across treatments. When measured using Michelson contrast, thresholds for bright spots on a bright background were significantly higher than for other scenarios, and the lowest threshold was found when dark spots were presented on dark backgrounds. Thresholds expressed in Weber contrast revealed increased contrast sensitivity for stimuli darker than their backgrounds, which is consistent with the literature. The RNL model was unable to estimate threshold scaling across scenarios as predicted by the Weber-Fechner law, highlighting limitations in the current use of the RNL model to quantify luminance contrast perception. Our study confirms that luminance contrast discrimination thresholds are context-dependent and should therefore be interpreted with caution.

WOS:000562536400007; International audience; Triggerfish are widely distributed in tropical waters where they play an important ecological role. The black triggerfish Melichthys niger may be the dominant species around oceanic tropical islands, whereas pelagic triggerfish, such as the ocean triggerfish Canthidermis sufflamen, can assemble around fish aggregating devices (FADs) where they are a common bycatch of tuna fisheries. In this study we combined acoustic and optical recordings to provide the first in situ target strength (TS) measurement of black and ocean triggerfish. Data were collected in the Archipelago of Fernando de Noronha off north-east Brazil. The mean TS of a 27.8-cm-long black triggerfish at 70 and 200 kHz was -39.3 dB re 1 m(2) (CV = 14.0%) and -38.9 dB re 1 m(2) (CV = 14.4%) respectively. The mean TS values of ocean triggerfish (with a size range of 39-44 cm) at 70 and 200 kHz were -36.0 dB re 1 m(2) (CV = 15.7%) and -33.3 dB re 1 m(2) (CV = 14.0%) respectively. This work opens up the field for acoustic biomass estimates. In addition, we have shown that TS values for ocean triggerfish are within the same range as those of small tunas. Therefore, acoustic data transmitted from FADs equipped with echosounders can introduce a bias in tuna acoustic biomass estimation and lead to increased rates of bycatch.

Place: Amsterdam Publisher: Elsevier WOS:000525305200009; Several pelagic fish species are known to regularly associate with floating objects in the open ocean, including commercially valuable species. The tuna purse seine industry takes advantage of this associative behavior and has been increasingly deploying free-drifting man-made floating objects, also known as fish aggregating devices (FADs). Using passive acoustic telemetry, this study describes the associative dynamics of the main targeted tropical tuna species (Thunnus albacores, T. obelus and Katsuwonus pelamis), as well as three major bycatch species, silky shark (Carcharhinus falciformis), rainbow runner (Elagatis bipinmdata) and oceanic triggerfish (Canthidermis maculata). Short-term excursions away from the FADs were frequently performed by all tuna species as well by silky sharks. These excursions were characterized by a marked diel pattern, mainly occurring during nighttime. Rainbow runners and oceanic triggerfish were much more present at the FADs and rarely performed excursions. Average continuous residence times (CRTs) ranged from 6 days, for silky shark, up to 25 days for bigeye tuna. Similar to silky shark, average CRTs for skipjack tuna and oceanic triggerfish were less than 10 days. For yellowfin tuna and rainbow runner, CRTs averaged 19 and 16 days, respectively. Bigeye and yellowfin tuna remained associated to a single drifting FAD for a record of 55 days and 607 km traveled.

Achromatic (luminance) vision is used by animals to perceive motion, pattern, space and texture. Luminance contrast sensitivity thresholds are often poorly characterised for individual species and are applied across a diverse range of perceptual contexts using over-simplified assumptions of an animal's visual system. Such thresholds are often estimated using the Receptor Noise Limited model (RNL) using quantum catch values and estimated noise levels of photoreceptors. However, the suitability of the RNL model to describe luminance contrast perception remains poorly tested. Here, we investigated context-dependent luminance discrimination using triggerfish (Rhinecanthus aculeatus) presented with large achromatic stimuli (spots) against uniform achromatic backgrounds of varying absolute and relative contrasts. ‘Dark’ and ‘bright’ spots were presented against relatively dark and bright backgrounds. We found significant differences in luminance discrimination thresholds across treatments. When measured using Michelson contrast, thresholds for bright spots on a bright background were significantly higher than for other scenarios, and the lowest threshold was found when dark spots were presented on dark backgrounds. Thresholds expressed in Weber contrast revealed increased contrast sensitivity for stimuli darker than their backgrounds, which is consistent with the literature. The RNL model was unable to estimate threshold scaling across scenarios as predicted by the Weber-Fechner law, highlighting limitations in the current use of the RNL model to quantify luminance contrast perception. Our study confirms that luminance contrast discrimination thresholds are context-dependent and should therefore be interpreted with caution.

WOS:000579495700004; Multispecies aggregations at floating objects are a common feature throughout the world's tropical and subtropical oceans. The evolutionary benefits driving this associative behaviour of pelagic fish remains unclear and information on the associative behaviour of non-tuna species remains scarce. This study investigated the associative behaviour of oceanic triggerfish (Canthidermis maculata) and rainbow runner (Elagatis bipinnulata), two major bycatch species in the tropical tuna purse seine fishery, at floating objects in the western Indian Ocean. A total of 24 rainbow runner and 46 oceanic triggerfish were tagged with acoustic transmitters at nine drifting FADs equipped with satellite linked receivers. Both species remained associated with the same floating object for extended periods; Kaplan-Meier survival estimates (considering the censored residence time due to equipment failure and fishing) suggested that mean residence time by rainbow runner and oceanic triggerfish was of 94 and 65 days, respectively. During daytime, the two species increased their home range as they typically performed short excursions (\textless2 h) away from the floating objects. Rainbow runner performed more excursions per unit time than oceanic triggerfish; the mean excursion index was 0.86 (±0.8 SD) for oceanic triggerfish and 1.31 (±1.1 SD) for rainbow runner. Ambient light intensity appears to be the stimulus triggering the onset and end of the associative modes. The observed prolonged residency of these two major bycatch species suggests that they are more vulnerable to the tropical tuna purse seine gear than the targeted tuna species.

Field removal and laboratory studies examined competitive interactions between gray triggerfish (Balistes capriscus) and red snapper (Lutjanus campechanus). In field studies, all gray triggerfish and red snapper were counted and sizes estimated on 24 reef sites. Gray triggerfish were then removed from half of these reef sites, resulting in significantly fewer gray triggerfish on the removal reefs at the start of the experiment. After 7 months the experiment ended and reef sites were resurveyed. Gray triggerfish decreased on both treatments, while the mean number of red snapper did not differ between treatments; however, there were significantly more small (

Caribbean spiny lobsters, Panulirus argus (Latreille, 1804), usually avoid sheltering with conspecifics exhibiting the PaV1 viral disease, yet commonly cohabit with them in large, low-lying artificial shelters called "casitas" that are deployed in shelter-poor habitats in certain fisheries. We tested two hypotheses proposed to explain this finding: (A) that in shelter-poor habitats, healthy lobsters make a trade-off between avoiding disease and avoiding predation; and (B) that the large size of casitas allows segregation between healthy and diseased lobsters. We conducted eight experiments in seawater tanks fitted with two casitas, one empty and one harboring either a healthy or a diseased tethered lobster ("resident"), or both harboring a healthy or a diseased resident. We then introduced six healthy, free-ranging lobsters (FR-lobsters) into each tank (three replicates per experiment) and recorded their location after approximately 40 hrs. Experiments were conducted with and without a predatory triggerfish. Without predators, FR-lobsters used empty casitas and those harboring healthy residents, but avoided casitas harboring diseased residents, preferring to remain in the open. With a predator present, FR-lobsters used empty casitas and those harboring healthy but also diseased residents, suggesting that disease avoidance depends to some degree on availability of alternate shelter and immediacy of predation risk. In larger casitas deployed in a reef lagoon, co-occurrence of wild diseased and healthy lobsters was relatively high, but the probability of finding diseased lobsters segregated from healthy lobsters decreased with increasing number of lobsters. Overall, the results support both hypotheses, reflecting the complex but flexible behavior of P. argus under different ecological contexts.

Two new species of Cardicola Short, 1953 (Aporocotylidae) are described from fishes from the Great Barrier Reef (GBR), Australia. Cardicola abu sp. n. infects the Whitley’s sergeant Abudefduf whitleyi Allen & Robertson (Pomacentridae), and is described from Wistari Reef of the Capricorn-Bunker Group, on the southern GBR. Cardicola yuelao sp. n. infects the halfmoon triggerfish Sufflamen chrysopterum Bloch & Schneider (Balistidae), and is described from off Lizard Island, on the far northern GBR. Morphological analysis and molecular phylogenetic analysis show both species agree with the concept of the genus Cardicola. Balistidae and Pomacentridae are new host families for Cardicola and for aporocotylids in general.

Pseudobalistes flavimarginatus (Ruppell, 1829) is a triggerfish species belonging to the Family Balistidae under the Order Tetraodontiformes. It was reported at the very first time from the region proximal to the south patches fishing ground of the Bay of Bengal (Bangladesh). The fish is known as Yellowmargin triggerfish due to the presence of body colour, yellow and gray. The total length of the voucher fish is 39.95 cm (Standard length 32.5 cm) and 1540 g by weight. It has a deep, moderately compressed body with inconspicuous lateral lines, encased in very thick and hard skin with large boney scales (except rostral region). The fish body bears two dorsal fins with three visible spines. Dorsal, anal and pectoral-fin rays are soft and branched. The taxonomic formula for the species is D III/27; A 0/25; P 15; V I/7; C 15; Lt. 35-36. Gill openings are moderately short, vertical to oblique slit in front of pectoral-fin base. Concerning distribution, the species is not reported before in Bangladesh and not even recorded from other maritime Bay of Bengal localities of Eastern India and Sri Lanka; whereas it was already reported in other bio-geographical regions (detailed in article). The voucher specimen is preserved at the Marine Fisheries Academy Museum, Bangladesh for further reference use.J. Biodivers. Conserv. Bioresour. Manag. 2017, 3(2): 85-90

The demersal fish are a commercial resource of small-scale fisheries of northern Colombian Caribbean. Balistes capriscus is frequently and important in fishing landings, but this species has not economic value and its trophic ecology is unknown. Due to this, the diet was examined using the stomach contents and stable isotopes analysis. The individuals were collected with fish pots during two seasonal research expeditions in May and August of 2018. The δN and δC values were significantly different between size classes, indicating ontogenetic shifts in habitat use and consumption of prey. The δC shows that the triggerfish tends to feed in areas closer to the coast and his source of its origin can possibly change from the pelagic zone when they are juveniles, to the benthic trophic networks in his adulthood. The trophic position mean according to Bayesian inferences and Post's estimates was 2.98 and 3.03 and increased with size. Likewise, isotopic niche width corroborates the ontogenetic shift related with the maturity groups., This study is framed in the research project “Marine environmental productivity and quality of the northern Colombian Caribbean as an axis for the regional development of the departments of La Guajira and Magdalena: analysis from the coupling of the atmospheric, oceanographic and biological components” executed by the research group DIMARCO (Jorge Tadeo Lozano University). This study was supported by the Magdalena and La Guajira governorates and operated and supervised by COLCIENCIAS (Code: 120274859287, CT-075-2017).

Recreational fishing is a growing sector of tourism, and in theory, can be done in a sustainable manner such as through catch-and-release where fish are released rather than harvested. In some cases, stakeholders have taken the initiative to develop conservation strategies and management guidelines, as well as establishing monitoring programs of the resources they use. In this work, we provide a case study of a cooperative monitoring program in the Alphonse Group, Republic of the Seychelles, Africa, between a fishing company (Alphonse Fishing Company) and a local non-governmental organization (Island Conservation Society). These efforts have resulted in a code of conduct for the catch-and-release of target species, as well as long-term spatially explicit monitoring of catches, including fish size and catch location for five popular species through catch logs. During three seasons, the five key fish species monitored were giant trevally (Caranx ignobilis, n = 684), moustache triggerfish (Balistoides viridescens, n = 141), Indo-Pacific permit (Trachinotus blochii, n = 99), milkfish (Chanos chanos, n = 55), and yellowmargin triggerfish (Pseudobalistes flavimarginatus, n = 46). We found monthly catch variability across all species and that catches across seasons increased for C. ignobilis (203.8%), T. blochii (45.5%), and B. viridescens (25%), and decreased for C. chanos (-65.6%) and P. flavimarginatus (-10%). Although there are considerations with implementing and maintaining such initiatives, we reviewed the benefits, including how these efforts can serve as the foundation for more thorough scientific research, co-production, and evidence-based management for the most sought-after species, C. ignobilis. We highlight how these cooperative initiatives may lead to formal co-management structures in recreational fishing, and also help to build capacity in government agencies for advancing economic prosperity while establishing sound long-term management and conservation strategies.

The levels of toxic heavy metals (Al, Cd, Pb), macroelements (Ca, K, Mg, Na) and microelements and trace elements (B, Ba, Co, Cr, Cu, Fe, Li, Mn, Mo, Ni, Sr, V, Zn) were determined in 54 muscle samples from three species of fish for human consumption, Balistes capriscus (grey triggerfish), Canthidermis sufflamen (oceanic triggerfish) and Heteropriacanthus fulgens (rock catalufa), using spectrometry of inductively coupled plasma optical emission (ICP-OES). The aims of this study is to determine if the three species are good bioindicators of environmental pollution and to verify whether they are suitable for human consumption. Significant differences were found in the levels of Al, B, Fe, K, Mn, Mo, Na and Zn between the three species studied. The results suggest that the underwater volcano off El Hierro influences the metallic content (Al, K the most characteristic) of H. fulgens. An evaluation of the toxic risk derived from the ingestion of B. capriscus, C. sufflamen and H. fulgens was carried out, analyzing the Admissible Daily Intake (ADI) and the Safety Margin (MoS). For the nutritional study, the Recommended Daily Intake (RDI) index was used. Therefore, once the study has been carried out and under the conditions established in terms of daily / weekly fish consumption, proposed by AESAN, there would not be any type of toxic risk after ingesting B. capriscus, C. sufflamen and H. cruentatus.