Large numbers of the leptomedusa Earleria bruuni were observed inside a semi-closed deep-sea caldera during a comparative survey of the macrozooplankton fauna inside and outside the Kurose Hole, Izu-Ogasawara Islands, by the remotely operated vehicle (ROV) ‘Dolphin-3K’, on 24 September 2000. The Kurose Hole is an inactive volcanic caldera of 790 m bottom depth, located within the Izu-Bonin island arc, south of Tokyo. Archived video and audio data from a dive by the human-occupied vehicle (HOV) ‘Shinkai 2000’, carried out 3 weeks after the ROV dives, was also analysed. During all dives within the caldera, E. bruuni was present in large numbers and, during the HOV dive, two specimens for morphological analysis were obtained. Herein, we report E. bruuni from the Pacific Ocean for the first time. The vertical profiles of environmental factors and the vertical distributions of gelatinous macrozooplankton taxa such as salps, ctenophores, hydromedusae, siphonophores and scyphomedusae, were extremely different inside and outside the caldera. Inside the caldera the water temperatures were warm and dissolved oxygen levels were high compared with outside. For each taxon, their distributions were characterized and compared between the inside and outside of the caldera, and with previous literature reports.

The present work on the feeding ecology of Scorpaena porcus according to season, sex and size, is the first study carried out in the rocky intertidal in the NE Atlantic. Previous studies were carried out with fish collected in fishing grounds from Mediterranean areas. A total of 106 fish were caught in monthly samplings from April 2008 to July 2010 in three areas of the rocky intertidal zone in the Gulf of Cadiz. The diet composition varied with season, size and sex. Shrimps were the main diet resource during all year, but other prey were also important depending on the season. As the size of fish increased, predation on smaller crustaceans decreased and consumption of larger crustaceans and fish augmented. Females and males based their diet on shrimps, while indeterminate fish fed largely on amphipods. No significant differences were found between feeding intensity and season, size and sex. Nevertheless, the PERMANOVA results showed that the number of prey is affected by the interaction between sex and size class. Our results highlight that S. porcus is a stenophagic species that shows a gradual segregation in the use of resources as it grows, which indicates there is no intraspecific competition in the rocky intertidal.

Early life traits (ELT) of the sand-burrowing cryptic marine fish Sindoscopus australis (family Dactyloscopidae) were compared between cohorts hatched during winter and spring 2013, in nearshore rocky reefs off central Chile. Pelagic larvae were similarly abundant during both periods, but larger larvae were collected during austral spring. The sagittal otolith microstructure and size analyses also indicated that size-at-hatch was larger (4.7 mm) for the winter cohort, but winter larvae experienced slower growth rates (0.145 mm day−1 ± 0.008). Conversely, larvae from the spring cohort hatched at smaller sizes (2.9 mm), but they grew faster (0.182 mm day−1 ± 0.008). Hatching periods were coupled with the lunar cycle; in winter, hatching events were related to neap tides (first and third quarter moon), increasing chances of self-recruitment. Meanwhile, during spring, hatching occurred during spring tides, particularly over the new moon, decreasing chances of larval mortality by predation. Otolith traits used to test asymmetry among cohorts showed inconsistent results. Only sagittal perimeter presented fluctuating asymmetry, showing higher variance for the winter cohort. We conclude that this burrowing species displays different reproductive tactics at a seasonal scale.

Both active and passive human interactions with reef fish communities are increasingly recognized to cause fish behavioural changes. However, few studies have considered how these behavioural adaptations impact standard reef survey techniques, particularly across natural gradients of interest to ecologists and reef managers. Here we measure fish abundance, biomass and minimum approach distance using stereo-video surveys to compare the effects of bubble-producing open-circuit scuba vs near-silent closed-circuit rebreathers. Surveys extended across a shallow to upper-mesophotic gradient on the fringing reefs of Utila, Honduras, to explore how the effects of diver gear choice vary with depth. For most fish families we recorded similar abundances and biomass with the two diving techniques, suggesting that open-circuit transects are generally appropriate for surveying western Atlantic reefs similar to Utila with regular tourist diving but no spearfishing. Despite no overall significant difference in fish abundance or biomass, we identified several fish families (Labridae, Pomacentridae, Scaridae) that allowed closed-circuit rebreather divers to approach more closely than open-circuit divers. In addition, smaller fish generally allowed divers to approach more closely than larger fish, and in most cases divers could approach fish more closely on mesophotic than shallow reefs. Despite these significant differences in approach distances, their magnitude suggest they are unlikely to affect reef fish detectability during normal fish surveys for most families. Our findings highlight the importance of considering variation in fish behavioural adaptations along natural gradients such as depth, which otherwise has the potential to cause biases when surveying by traditional monitoring programmes.

The prevalence of scars and wounds of anthropogenic origin was assessed in seven different coastal bottlenose dolphin communities (Tursiops truncatus) on the south-western coast of Ecuador. Between 2011 and 2017 a total of 117 trips were conducted representing a total sampled distance of 6281 km. Twenty-five of the 189 (13.2%) free-ranging photo-identified dolphins were recorded with dorsal fin damage, V-shaped wounds, sawed edges and deformities in the caudal region. The scarring prevalence ranged from 0 to 44.4% and was associated with either fishing interactions or vessel strikes. Dolphin scarring increased five times in the last 25 years from 2.2 to 11.1% and was correlated with a decrease in population in the inner estuary of the Gulf of Guayaquil. Damaged dorsal fins are associated mainly with fishing gear. V-shaped wounds were recorded in three different communities, Posorja, Estero Salado and Salinas, and given their severity associated with either fishing gear or vessel strikes. During the study period three dolphins were found entangled in fishing gears, two in gillnets and one in a long-line, emphasizing the threats posed by current fishing practice to the species. More effective management measures are urgently needed to reverse the observed population decline. This may include reduction of fishing effort, implementation of area-based approaches to coastal planning (including Marine Protected Area designations) and support for further research to understand the problem. Given the difficulty in taking direct observations, scarring prevalence is proposed as a proxy for estimating boat traffic and fishing gear impacts upon cetaceans.

The catfish Genidens barbus is a commercial species from South America. The aim of the present study was to examine the inter-annual variability in estuary-specific chemical signatures of otolith cores (Ba:Ca, Mg:Ca, Mn:Ca, Sr:Ca and Zn:Ca ratios) for three estuaries from Argentina and Brazil where adults were collected over multiple years. Secondarily, we evaluated whether the percentages of classification of individuals to their natal origin place are affected by the grouping of several cohorts. Most element:Ca ratios were not significantly different among year cohorts. Results from PERMANOVA revealed significant differences in the multi-element signatures of the otolith core between cohorts for the Plata River estuary (PR) (P = 0.006) and the Patos Lagoon (PL) (P = 0.03), while no significant differences (P = 0.9) were found for Paranaguá Bay (PB). The percentages of spatial classification (discriminant function analyses) decreased to between 15.5 and 25% for PR and PL when cohorts were grouped. This work makes it clear that the temporal variation in the chemical signature of the adult catfish otolith core can greatly affect the percentages of spatial classification.

Short-term measures of behavioural responses of cetaceans to tourism operations have been used in many studies to interpret and understand potential long-term impacts of biological importance. The short-beaked common dolphin (Delphinus delphis) is the species most frequently observed in the Azores and constitutes an important component of the marine mammal tourism industry in this region. This study investigated the potential effects of tour boats on the behaviour of common dolphins off São Miguel, Azores, with particular focus on the changes in activity budget and the time required to resume activities after a tour boat interaction. Behavioural data were collected from land using a group focal-follow methodology. Markov chains were applied to analyse control and interaction sequences and to assess behavioural transition probabilities in both scenarios. In the presence of tour boats, dolphins significantly reduced the time spent foraging and increased the time engaged in other high energy activities. Dolphins also took significantly longer to resume feeding after an interaction occurred. The average bout length varied significantly between control and interaction scenarios, with foraging bouts being shorter during tour boats interactions. The results presented have management implications since feeding is a biologically critical activity. Disruption of foraging behaviour could lead to a decrease in energy intake for this population. With cetacean tourism likely to increase in the future, a precautionary approach to issuing new licences is advisable and any expansion would warrant an appropriate monitoring programme.

A freshly dead individual of the giant squid Architeuthis dux, presumably mutilated by a predator of bigger or comparable size, is reported from the south-western Indian Ocean in proximity to Reunion Island. The species was identified from body and beak morphology and validated genetically. The dorsal mantle length (DML) estimated from beak measurements (lower rostral length, LRL) varied between 2153 and 3060 mm depending on the allometric equation used. The Architeuthis dux individual described here is the biggest giant squid ever reported for the region.

Temporal variations over short and medium time scales play an important role in fish assemblage dynamics, but have been poorly investigated in tropical estuaries. This study evaluates the hypothesis that fishes co-occurring on a tidal mudflat have different patterns of temporal segregation at short- and medium-term scales that optimize resource use and habitat partitioning. A total of 6222 individuals and 66 fish species were caught during different hours covering the entire 24 h cycle, tidal regimes and the wet and dry seasons. Biomass and species richness, and to a lesser extent CPUE and evenness, showed statistically significant interactions across short- and medium-term scales. Biomass was higher during the dry season and its oscillation along tidal cycles revealed distinct patterns over the photoperiod in each season. A similar complex pattern was also observed for species richness, which showed distinct temporal patterns between high and low tides over the photoperiod in each season. Overall, shorter-term variations on fish assemblage attributes were correlated mainly with photoperiod and, to a lesser extent, tidal regime. Medium-term variations in fish abundance and species richness, in contrast, could result from seasonality in recruitment patterns and higher availability of allochthonous food resources during the wet period.

This paper presents the results of a comparative study of five osteological complexes, the infraorbital bones, branchial arches, urohyal bone, interdigitation of the median fins, and the caudal fin skeleton, of some members of the fish family Tripterygiidae. Osteological characters that may prove valuable for taxonomic purposes are described, and on the basis of the material handled, their use to separate species within the family is discussed. Several formulae were developed for the distribution of the osteological complexes of the dorsal fin, dorsal and ventral caudal procurrent ray distribution, and caudal fin in the different tripterygiid species studied.

Two female snapper-choking isopods Cymothoa excisa (body length 11 and 14 mm) were in the buccal cavity of two invasive lionfish Pterois volitans (total length 294 and 301 mm) collected in Alacranes Reef, southern Gulf of Mexico. This is the first record of C. excisa parasitizing invasive lionfish P. volitans in coral reefs of the Western Atlantic, where these isopods appear to have infected the host through adult prey-predator transfer.

Knowledge of growth patterns of an animal species is fundamental to understand their life history. This information is also used to help define population boundaries of threatened cetaceans, such as the Franciscana dolphin, Pontoporia blainvillei. A total of 108 Franciscana dolphins incidentally captured in artisanal fishing nets in estuarine and marine coastal waters of the northern part of the Franciscana Management Area IV (North FMA IV), Argentina, were studied. The objective of the present paper was to study age and growth parameters of Franciscanas from North FMA IV and to compare these parameters between estuarine and marine potential populations within this area. We used von Bertalanffy and Gompertz growth curves to model growth trajectories. The estimated asymptotic lengths demonstrated that Franciscana dolphins from this area were smaller (females: 136.3 cm and males, 122.1 cm) than southern FMA IV values previously published. They also showed the reverse sexual size dimorphism that is known across their range. However, the estimated asymptotic length was not statistically different between the estuarine and marine females within the study area. In spite of this, the fact that the northern forms of the FMA IV were smaller than the southern specimens supports the hypothesis of more than one population of the species within this management area. The North FMA IV has the highest reported mortality levels of Franciscana dolphins within the FMA IV; these results are relevant to the knowledge base of Franciscana dolphins in the region.

The diet and feeding behaviour of the forkbeard Phycis phycis was studied based on 246 stomachs collected between May 2011 and April 2012 from a commercial fleet operating off the central west coast of Portugal. A total of 44 prey items were identified in the stomachs which were merged into major groups to avoid problems with low expected frequencies. The following taxonomic categories were considered: non-decapod Crustacea, Caridea, Anomura, Munida spp., Processa spp., Brachyura, Pisces, Trisopterus luscus. In order to investigate possible diet differences between fish size classes, a cluster analysis was performed using the mean abundance of each prey group by forkbeard 5 cm length class, and three length groups (LG) were obtained: <22.5, 27.5–37.5 and >42.5 cm. Seasonally, Caridea was the main prey group during winter and autumn while Pisces was predominant during the rest of the year. Caridea was the most important prey group for LG1 and LG2 while in LG3 Pisces was the principal one. The forkbeard feeding behaviour may be characterized as presenting a shift pattern from a more generalist diet (small Crustacea, mainly Caridea) in the young adults to a more specialist strategy (teleosts) in the adults.

This study aimed to describe the ethnoecology of the franciscana (Pontoporia blainvillei) using the traditional knowledge of artisanal fishermen in the villages of Peças Island (VPI) and Superagui Island (VSI) in the World Heritage listed Paranaguá Estuarine Complex, Brazil. Between March and September 2012, 90 fishermen were interviewed (VPI – 40; VSI – 50) using a semi-structured questionnaire. Using Fuzzy logic (MATLAB 7.6) it was verified the species is easily recognized by body size, colour and occurrence area (VPI – 87.5%; VSI – 38.0%). Fishermen most frequently identified adults and young franciscanas in groups of two to five individuals (VPI – 40.0%; VSI – 58.0%). Adults were sighted throughout the year, while the young were restricted to summer and winter. Five common behavioural ethno categories were described: ‘eat’ (VPI – N = 15; VSI – N = 1); ‘float/sink/dive’ (VPI – N = 34; VSI – N = 12); ‘breathe’ (VPI – N = 11; VSI – N = 5); ‘mothers surrounding the shoal, play caught up and the youth captures’ (suggesting care parental related with feeding of infant) (VPI – N = 1; VSI – N = 2); and ‘to play’ (VPI – N = 6; VSI – N = 1). The information from the fishermen highlights the use of the area by franciscana for feeding and reproduction and these data are comparable with the literature. These results extend the knowledge about the species in an area of ecological interest and the traditional knowledge, but also illustrate the benefits of engaging fishermen to promote collaboration in scientific and management processes.

The stomach contents of 1261 striped marlins caught from 2007 to 2010 by the sport-fishing fleet of Cabo San Lucas, Baja California Sur, Mexico, were analysed, taking into account sea surface temperatures estimated using satellite images of the study area and the Oceanic Niño Index (ONI). The analysis allowed the identification of three anomalously cold periods during 2007, 2008 and 2010 and a warm period in 2009. The stomach content results showed 89 different prey items eaten during the study period. Of the specimens captured, 868 (69%) stomachs contained food items. The most important prey items were cephalopods (Dosidicus gigas and Argonauta spp.) and fish (Scomber japonicus, Selar crumenophthalmus and Sardinops caeruleus). Despite having a broad trophic spectrum, the striped marlin was classified as a specialist consumer, with Bi = 0.03. Based on the diet breadth value and the prey-specific index of relative importance (PSIRI), the jumbo squid, D. gigas, was the main prey species, coinciding with cold periods. On the other hand, the fishes S. caeruleus and S. japonicus showed the highest PSIRI values during the 2009 warm anomalies. Analysis of similarity showed the formation of four groups in relation to PSIRI values. According to a non-metric multidimensional scaling ordination, these groups were formed with a similarity of 30% and a stress of 0.17. These results demonstrate inter-annual variation in the diet as well as in the availability and abundance of prey items.

Length-weight relationships were calculated for 48 fish species from İzmir Bay in the Aegean Sea, Turkey. A total of 3584 fish specimens were captured with beach seine, handline, fyke net, scoop net, castnet and trammel net in 2010–2014. The sample size ranged from three individuals for Squatina squatina to 140 for Mugil cephalus. R2 values varied between 0.95 for Pomatoschistus bathi and 0.99 for Argyrosomus regius, Chelon labrosus and Mugil cephalus. All regressions were highly significant (P < 0.001). Values of the exponent b in the length-weight regression (W = aLb) ranged from 2.750 for S. squatina to 3.514 for Syngnathus acus and the median value was 3.134 with 25–75% of the values ranging between 3.030 and 3.218.

The five sea turtle species occurring in Brazilian waters are susceptible to threats, including incidental catches by fisheries. Studies on incidental captures in fishing gears are the main focus of several conservation actions due to high sea turtle fishery mortality worldwide. This study provides the first evaluation of incidental sea turtle catches by industrial bottom trawl fisheries operating in Brazilian waters. Four twin-trawler vessels were monitored between July 2010 and December 2011 by captains who voluntarily completed logbooks. Forty-four turtles were captured during the 1996 tows (8313 fishing hours), resulting in a catch of 5.3 ± 0.8 turtles per 1000 h per unit effort. Captured species included the loggerhead turtle (Caretta caretta, 22 individuals), olive ridley turtles (Lepidochelys olivacea, 21 individuals) and one green turtle (Chelonia mydas). Water depth was the only variable that significantly affected sea turtle captures according to Generalized Linear Models. The capture rates reported in this study ranked sixth in relation to other published studies of similar fisheries occurring worldwide. Considering the importance of this region for sea turtles, the increasing evidence of sea turtle mortality and the goals of the National Action Plan for Conservation of Sea Turtles in Brazil, it is essential to identify the main threats towards these animals and propose mitigating solutions to reduce sea turtle mortality induced by fishing activities. This study provides results that may guide future research and goals in meeting sea turtle conservation strategies.