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Increasing sea temperature is a driver of change for many fish traits, particularly for fast-growing epipelagic species with short life spans. With warming, altered spawning phenology and faster growth may produce substantially larger body sizes of the new cohort, affecting fishery productivity. We present an individual-based model (IBM) that predicts the distribution of fish length at catch under observed and projected thermal scenarios, accounting for mortality, temperature-dependent spawning phenology, temperature- and photoperiod- dependent growth. This IBM was demonstrated with Coryphaena hippurus (common dolphinfish), a circumglobally-distributed and highly thermophilic species sustaining commercial and recreational fisheries where it is present. The model projected a 13.2% increase in the average length at catch under marine heatwave conditions compared to the current thermal regime (1995–2005 average). Projections under RCP scenarios 4.5 and 8.5 by the end of the century led to 5.1% and 12.8% increase in average length, respectively. Furthermore, these thermal scenarios affected spawning phenology differently, producing higher variance in body size under RCP 8.5 scenario with respect to marine heatwave conditions. This study highlights how the environmental effects of climate change can alter the distribution of species length at catch., The present paper is part of the CERES project (H2020, EU 678193). Part of the data was obtained from the FAO-Copemed and FAO-Copemed II projects (http://www.faocopemed.org/). This study has been conducted using E.U. Copernicus Marine Service Information. V. Moltó acknowledges a predoctoral grant funded by the Regional Government of the Balearic Islands and the European Social Fund, A. Ospina Álvarez was supported by H2020 Marie Skłodowska-Curie Actions (746361), and S. Pérez-Mayol salary was founded by PN Project DREAMER (CTM2015-66676-C2-1-R). We also acknowledge Andreina Fenech, Marie Louise Pace, and Roberta Mifsud from the Department of Fisheries and Aquaculture of Malta for the data collection and provision.

53 striped surmullet, Mullus surmuletus Linnaeus, 1758 (Teleostei, Mullidae), were collected from the Marmara Sea, Turkey and examined for metazoan parasites in July 2017. The parasitic copepod, Peniculus fistula fistula Nordmann, 1832 (Pennellidae), was collected from all the hosts, both on fins and body surface. This is the second report of this copepod in Turkish marine waters. Although Peniculus fistula fistula was reported for the first time on Coryphaena hippurus Linnaeus, 1758 by Öktener (2008), there was an indefiniteness and doubt about the occurrence of this parasite. This study aimed to confirm occurrence of Peniculus fistula fistula in Turkey and to present revised host list with comments.

Crude oil-derived polycyclic aromatic hydrocarbons (PAHs) are pervasive environmental pollutants with well-established detrimental effects on the health of marine organisms. Following large-scale oil spills in the marine environment, there is a critical need for noninvasive sampling methods to assess environmental exposure to PAHs without further perturbations to the population and for long-term monitoring following a spill. To test the efficacy of epidermal mucus mRNA as a source for noninvasive sampling, juvenile mahi-mahi (Coryphaena hippurus, ∼28 days of age) were exposed to control seawater or two concentrations of high-energy water accommodated fractions (HEWAFs; 5% or 10%) of Deepwater Horizon surface oil for 48 h. Whole-transcriptome sequencing revealed differential expression of 501 transcripts in the low-HEWAF exposure (∑PAH = 16.55 μg/L) and 196 transcripts in the high-HEWAF exposure (∑PAH = 23.03 μg/L), suggesting differential regulation of mRNA in mucus following PAH exposure. In addition to ...

To gain a better understanding of the trophic ecology of Pacific blue marlin Makaira nigricans off eastern Taiwan, nitrogen and carbon stable isotopes (δ15 N and δ13 C) and Bayesian mixing models were used to explore trophic dynamics and potential ontogenetic feeding shifts across M. nigricans of different size classes. Makaira nigricans samples from east of Taiwan (n = 213) and Palau (n = 37), as well as their prey (n = 70), were collected during 2012 and 2013. Results indicated increases in δ15 N with size, with values of larger size classes (> 200 cm eye-to-fork length; LEF ) significantly higher than those 200 cm LEF had the highest estimated trophic position (4.44) and also exhibited ontogenetic changes in trophic position. Large M. nigricans fed more on dolphinfish Coryphaena hippurus and hairtail Trichiurus lepturus, while smaller M. nigricans consumed smaller forage fish (e.g., moonfish Mene maculata) and cephalopods. These changes may relate to greater swimming speeds and vertical habitat use in larger M. nigricans, allowing capture and consumption of larger prey items at higher trophic positions. The high trophic level of M. nigricans east of Taiwan confirms its important role as an apex predator in marine food webs and how ecological role changes with size.

The study investigates feeding habits of thermophilic species and species with subtropical affinity in the fishing catch in the Bay of Medulin (northeastern Adriatic Sea), and contributes to the knowledge about their presence in recently extended distributional range. In our methodology, the presence of the Seriola dumerili, Sphyraena sphyraena, Lichia amia, Coryphaena hippurus, Caranx crysos, Pomatomus saltatrix, and incidence of Trachinotus ovatus is recorded. A total of 220 specimens are captured during 2017, 2018 and 2019. A dietary assessment is performed, and the index of relative importance IRI was calculated for each prey category. Diet overlap is calculated using Schoener’s index, based on IRI. The principal diet of C. hippurus included Sardina pilchardus and Loligo vulgaris. Pomatomus saltatrix consumed species from the Sparidae family and T. ovatus crustaceans from the Mysidacea family. Different species from genus Atherina are represented important foods for L. amia, S. dumerili and S. sphyraena. Diets of significant importance for L. amia included fishes from the family Sparidae, for S. sphyraena from the Carangidae family, and S. dumerili from the Clupeidae and Muliidae families. Our analysis of diet overlap is based on IRI suggests no diet overlap between analysed fish species from Medulin Bay, and that these species utilise differing trophic niches.

Deepwater Horizon (DWH) oil causes developmental cardiotoxicity in fish species, but the molecular mechanisms are still not well understood. MicroRNAs (miRNAs) play key roles in a number of biological processes, including heart development. Therefore, the expression of miRNAs in mahi-mahi (Coryphaena hippurus) exposed to weathered slick oil and nonweathered source oil was analyzed. miRNAs were sequenced and annotated using the Fugu rubripes genome (termed the Fugu-guided approach) or aligned with known mature animal miRNAs using the Basic Local Alignment Search Tool (BLAST) method (termed the phylogenetically guided approach). Exposure of embryos to slick oil resulted in more differentially expressed miRNAs than exposure to source oil at all developmental stages. Gene ontology analysis on the target mRNAs was consistent with pathway analysis of miRNAs, predicting disruption of cardiovascular system development after oil exposure, and specific miRNA–mRNA interactions identified by ingenuity pathway analysi...

Deep-water demersal fishes represent an understudied but ecologically important group of organisms. Select species of demersal fishes rely on pelagic prey items, representing a direct transport of surface carbon to greater depths. Barrelfish,Hyperoglyphe perciformis (Mitchell, 1818), which inhabit deep slope waters, are a species that has been suggested to fill this role, as congeners consume primarily pelagic gelatinous zooplankton. However, there is a dearth of information on the trophic ecology of barrelfish. Stomach content and stable isotope analyses were conducted on 29 barrelfish caught by recreational fishers from November 2014 to November 2015 off Miami, Florida, to improve our understanding of the feeding of this species.Pyrosoma atlanticum Peron, 1804, a pelagic, vertically migrating tunicate, represented 89% of the barrelfish diet by weight. Mesopelagic fish and shrimp contributed much smaller proportions. Standard ellipse areas corrected for sample size (SEAc ) showed a substantially smaller isotopic niche width for barrelfish (n = 26, 0.606 ‰2) than dolphinfish, Coryphaena hippurus Linnaeus, 1758 (n = 36, 2.16 ‰2), king mackerel,Scomberomorus cavalla (Cuvier, 1829) (n = 17, 3.04 ‰2), or wahoo,Acanthocybium solandri (Cuvier, 1832) (n = 12, 1.97 ‰2). Coupled with dependence on a singular prey item, the low SEAc of barrelfish suggests they occupy a limited trophic niche space. Overlap of barrelfish SEAc with dolphinfish (99.5% overlap) and king mackerel (100% overlap) indicate that the carbon sources and the number of trophic steps for barrelfish are similar to king mackerel and dolphinfish, and are linked to surface waters. This trophic linkage suggests that barrelfish may play a role in carbon export and further study of their behavior and daily consumption rates is warranted for quantifying this role.

Seasonal forecasting of environmental conditions and marine species distribution has been used as a decision support tool in commercial and aquaculture fisheries. These tools may also be applicable to species targeted by the recreational fisheries sector, a sector that is increasing its use of marine resources, and making important economic and social contributions to coastal communities around the world. Here, a seasonal forecast of the habitat and density of dolphinfish (Coryphaena hippurus), based on sea surface temperatures, was developed for the east coast of New South Wales (NSW), Australia. Two prototype forecast products were created; geographic spatial forecasts of dolphinfish habitat and a latitudinal summary identifying the location of fish density peaks. The less detailed latitudinal summary was created to limit the resolution of habitat information to prevent potential resource over-exploitation by fishers in the absence of total catch controls. The forecast dolphinfish habitat model was accurate at the start of the annual dolphinfish migration in NSW (December) but other months (January - May) showed poor performance due to spatial and temporal variability in the catch data used in model validation. Habitat forecasts for December were useful up to five months ahead, with performance decreasing as forecast were made further into the future. The continued development and sound application of seasonal forecasts will help fishery industries cope with future uncertainty and promote dynamic and sustainable marine resource management.

Identifying prey resource pools supporting fish biomass can elucidate trophic pathways of pollutant bioaccumulation. We used multiple chemical tracers (carbon [δ(13)C] and nitrogen [δ(15)N] stable isotopes and total mercury [THg]) to identify trophic pathways and measure contaminant loading in upper trophic level fishes residing at a reef and open-ocean interface near Eleuthera in the Exuma Sound, The Bahamas. We focused predominantly on the trophic pathways of mercury bioaccumulation in dolphinfish Coryphaena hippurus and wahoo Acanthocybium solandri, 2 commonly consumed pelagic sportfish in the region. Despite residing within close proximity to productive and extensive coral reefs, both dolphinfish and wahoo relied almost exclusively on open-ocean prey over both short and long temporal durations. A larger isotopic niche of dolphinfish suggested a broader diet and some potential prey differentiation between the 2 species. THg concentrations in dolphinfish (0.2 ± 0.1 ppm) and wahoo (0.3 ± 0.3 ppm) were mostly below recommended guidelines for humans (US Environmental Protection Agency (EPA) = 0.3 ppm, US Food and Drug Administration (FDA)= 1.0 ppm) and were within ranges previously reported for these species. However, high THg concentrations were observed in muscle and liver tissue of commonly consumed reef-associated fishes, identifying a previously unrecognized route of potentially toxic Hg exposure for human consumers on Eleuthera and neighboring islands.

Dolphinfish is an important fish species for both commercial and sport fishing, but so far limited information is available on genetic variability and pattern of differentiation of dolphinfish populations in the Mediterranean basin. Recently developed techniques allow genome-wide identification of genetic markers for better understanding of population structure in species with limited genome information. Using restriction-site associated DNA analysis we successfully genotyped 140 individuals of dolphinfish from eight locations in the Mediterranean Sea at 3324 SNP loci. We identified 311 sex-related loci that were used to assess sex-ratio in dolphinfish populations. In addition, we identified a weak signature of genetic differentiation of the population closer to Gibraltar Strait in comparison to other Mediterranean populations, which might be related to introgression of individuals from Atlantic. No further genetic differentiation could be detected in the other populations sampled, as expected considering the known highly mobility of the species. The results obtained improve our knowledge of the species and can help managing dolphinfish stock in the future.

The Deepwater Horizon (DWH) oil spill contaminated the spawning habitats for numerous commercially and ecologically important fishes. Exposure to the water accommodated fraction (WAF) of oil from the spill has been shown to cause cardiac toxicity during early developmental stages across fishes. To better understand the molecular events and explore new pathways responsible for toxicity, RNA sequencing was performed in conjunction with physiological and morphological assessments to analyze the time-course (24, 48, and 96 h post fertilization (hpf)) of transcriptional and developmental responses in embryos/larvae of mahi-mahi exposed to WAF of weathered (slick) and source DWH oils. Slick oil exposure induced more pronounced changes in gene expression over time than source oil exposure. Predominant transcriptomic responses included alteration of EIF2 signaling, steroid biosynthesis, ribosome biogenesis and activation of the cytochrome P450 pathway. At 96 hpf, slick oil exposure resulted in significant perturbations in eye development and peripheral nervous system, suggesting novel targets in addition to the heart may be involved in the developmental toxicity of DHW oil. Comparisons of changes of cardiac genes with phenotypic responses were consistent with reduced heart rate and increased pericardial edema in larvae exposed to slick oil but not source oil.

Age and growth of the dolphinfish Coryphaena hippurus caught off north-eastern Brazil were studied by counting growth increments on scales and otoliths. A sample (n = 2338) measuring 7·7-195 cm fork length (LF ) was collected from September 2001 to February 2003. The scales (n = 69) removed from six different regions of the body were examined and those from the caudal region exhibited greater morphological regularity, symmetry and a smaller rate of regeneration. The regression between caudal scale radius (RS ) and LF displayed was linear (LF = 28·334 RS + 9·186; r(2) = 0·754). Otolith micro-increments were counted assuming daily periodicity. Ages estimated from otoliths ranged from 64 to 659 days. The von Bertalanffy growth model was fitted based on the otolith readings generating L∞ = 194·1 cm LF , k = 0·912 year(-1) and t0 = 0·081 years. Species longevity was estimated to be c. 4 years. Ninety-eight per cent of the overall sample was adult specimens well above the age of first maturity in the study area. The large variability between scale length and LF and the failure to ascertain increment deposition periodicity suggest that scales are not appropriate for ageing C. hippurus and analysis of otolith micro-increments is deemed the best structure for ageing this species in the study area.

Fisheries management based on an ecosystem approach is currently promoted and, to this end, knowledge of interactions between the components of pelagic ecosystem is crucial. The aim of this study was to evaluate the trophic interactions between some components of marine pelagic ecosystem off the coast of Oaxaca. The stomach contents of five species of fishes caught during fishing tournaments and commercial fishing at the coast of Oaxaca, from May 2000 to July 2002 were analyzed. We analyzed stomach contents of 645 specimens of large predatory fishes, namely Istiophorus platypterus, Coryphaena hippurus, Thunnus albacares, Euthynnus lineatus, and Carcharhinus falciformis. Mayor forage species were Portunus xantusii and Auxis thazard: all predators consumed them in greater or lesser amounts. All fish species had narrow trophic niche breadths (BA

The common dolphinfish (Coryphaena hippurus) is an epipelagic, mid-trophic level, highly migratory species distributed throughout the world’s tropical and subtropical oceans in waters greater than 20°C. Life-history variables, migratory behaviour, and genetic markers have been used to define major stocks in the central Atlantic Ocean and Mediterranean Sea. Here, we used the mitochondrial DNA gene NADH subunit 1 (688 bp) to test for differences between population groups. A total of 103 haplotypes were detected among 203 fish. Gene diversities in samples were large and similar among populations (mean h = 0.932; range 0.894–0.987), but nucleotide diversities varied widely among samples (range π = 0.004–0.034) and appear to reflect population histories. Principal component analysis revealed two large populations groups, and the analysis of molecular variation and pairwise values of ΦST resolved population structure within these groups. Populations in the eastern Atlantic and Mediterranean showed the largest amounts of divergence from one another (ΦCT = 0.331). Adult movement and biophysical barriers to larval dispersal may explain contemporary differences between stocks, but the divergent populations in the Mediterranean Sea are likely due to isolations by cold temperature barriers during Pleistocene glaciations. The geographically large stock groupings require international cooperation in the harvest management and conservation of local dolphinfish populations.

The common dolphinfish (Coryphaena hippurus) is widely distributed and represents an important part of the currently exploited fishery resources. This species’ feeding behaviour, however, is poorly understood. This study aimed to investigate the feeding behaviour of dolphinfish and the effect of body size (and the consequently aggregated learning experience) on the strategies used for capturing their prey. Observations were made from an oil platform in north-eastern Brazil. Dolphinfish length was visually estimated and classified into three size classes. The following foraging strategies were observed in our study: ‘active chasing’, ‘leaping out’, ‘swimming in circles’, ‘surf’, ‘using floating objects’ and ‘cleaning turtle carapaces’. The most frequently used foraging strategy was ‘active chasing’, suggesting a strong preference of dolphinfish in using visual cues during predation. Smaller size-classes of dolphinfish did not perform the ‘swimming in circles’ and ‘surf’ strategy, probably due to a lack of learning experience, since further social interactions could be needed in order to show this strategy. Smaller dolphinfish regularly showed the ‘using floating objects’ as a foraging strategy, probably reflecting an opportunistic behaviour. The smallest individuals were using more simple strategies, to chase smaller prey that could have different and less complex escape strategies. It indicates learning experience could play an important role into the dolphinfish ontogeny, moving towards more complex foraging strategies throughout their lives. Independently of the age class, the dolphinfish displayed a varied repertory of foraging strategies, maximizing hunting success in the open ocean, a hostile pelagic environment with a low prey availability.

Migratory pelagic fish species, such as the mahi-mahi (Coryphaena hippurus), must balance numerous metabolic demands simultaneously in order to survive in a challenging oceanic environment. Energetic support for such demands comes from a variety of natural prey items in the wild and can come from manufactured pelletized feed in captivity. This study quantified postprandial metabolism, commonly referred to as specific dynamic action (SDA), over time in adult mahi-mahi (706±25g; 38±0.7cm FL) in response to satiation feeding using three different natural and manufactured diets. Results indicate that during satiation feeding the amount of food ingested is dictated by energy content rather than prey mass, regardless of moisture content of the diet. Ingested meal energy did not differ significantly across groups (473±45kJ), nor did the duration of SDA (36±2.1h). Satiation feeding levels ranged from 2.9-16.2% bodyweight depending on the diet. Peak SDA and SDA magnitude were both significantly decreased in response to dry pelletized diet compared to the natural forage diets, despite equivalent energy consumption. Swim performance and maximum metabolic rate were not impacted significantly in satiation fed fish compared to unfed fish, supporting the evidence that mahi-mahi are able to maintain multiple metabolic demands at one time without compromising performance.

The Deepwater Horizon oil spill occurred in the summer of 2010 and coincided with the spawning window of the ecologically and economically important pelagic fish mahi-mahi (Coryphaena hippurus). During summer months, early life stage mahi-mahi were likely also exposed to other naturally occurring stressors such as increased temperature and ultraviolet radiation (UV). Previous research has shown that co-exposure to oil and additional natural stressors can affect the timing and duration of negative buoyancy in mahi-mahi embryos. The current study aimed to elucidate the factors affecting the onset of negative buoyancy and to also explore possible mechanisms behind buoyancy change. Embryos co-exposed to oil and/or increased temperature and UV radiation displayed early onset of negative buoyancy with concurrent increases in oxygen consumption and sinking rates, which are normally only seen during the period directly preceding hatch. Results also suggest a behavioral response in which embryos avoid UV radiation by sinking down the water column but reestablish positive buoyancy once the UV radiation is removed. These findings imply that embryos can dynamically change their position in the water column in response to external cues and thus may have much greater control over buoyancy than previously thought.

The impacts of Deepwater Horizon (DWH) oil on morphology and function during embryonic development have been documented for a number of fish species, including the economically and ecologically important pelagic species, mahi-mahi (Coryphaena hippurus). However, further investigations on molecular events and pathways responsible for developmental toxicity have been largely restricted due to the limited molecular data available for this species. We sought to establish the de novo transcriptomic database from the embryos and larvae of mahi-mahi exposed to water accommodated fractions (HEWAFs) of two DWH oil types (weathered and source oil), in an effort to advance our understanding of the molecular aspects involved during specific toxicity responses. By high throughput sequencing (HTS), we obtained the first de novo transcriptome of mahi-mahi, with 60,842 assembled transcripts and 30,518 BLAST hits. Among them, 2,345 genes were significantly regulated in 96hpf larvae after exposure to weathered oil. With comparative analysis to a reference-transcriptome-guided approach on gene ontology and tox-pathways, we confirmed the novel approach effective for exploring tox-pathways in non-model species, and also identified a list of co-expressed genes as potential biomarkers which will provide information for the construction of an Adverse Outcome Pathway which could be useful in Ecological Risk Assessments.

The dolphinfish, Coryphaena hippurus Linnaeus, 1758, is an important target species for Mediterranean artisanal, recreational and commercial fisheries but to date only scarce genetic data are available for its Mediterranean population(s). The genetic variation of Mediterranean dolphinfishes was thus investigated through the sequencing of fragments of the cytochrome c oxidase subunit 1 (COI) gene and the NADH dehydrogenase subunit 1 (ND1) mitochondrial DNA markers with the explicit aims of (i) testing for significant genetic differentiation of the Mediterranean vs . non-Mediterranean populations of the species, and (ii) investigating the possible presence of molecular structuring within the Mediterranean basin. Performed analyses revealed significant genetic differentiation between Mediterranean and Atlantic dolphinfish population, while no significant geographically-based genetic differentiation was detected within the Mediterranean basin. The apparent lack of genetic structuring at the Mediterranean level is likely due to the highly mobile behaviour of the species, which is typical of large pelagic fishes and in agreement with the few tag data currently available. Based on presented results, the Mediterranean dolphinfishes are thus suggested to be considered a distinct management unit from those outside the Mediterranean. Conversely, in order to test for the presence of a single vs. multiple Mediterranean stock units, the fulfillment of further analyses implementing fast-evolving nuclear markers is advisable.

Negative impacts of CO2-induced ocean acidification on marine organisms have proven to be variable both among and within taxa. For fishes, inconsistency confounds our ability to draw conclusions that apply across taxonomic groups and highlights the limitations of a nascent field with a narrow scope of study species. Here, we present data from a series of 3 experiments on the larvae of mahi-mahi Coryphaena hippurus, a large pelagic tropical fish species of high eco- nomic value. Mahi-mahi larvae were raised for up to 21 d under either ambient seawater condi- tions (350 to 490 µatm pCO2) or projected scenarios of ocean acidification (770 to 2170 µatm pCO2). Evaluation of hatch rate, larval size, development, swimming activity, swimming ability (Ucrit), and otolith (ear stone) formation produced few significant effects. However, larvae unex- pectedly exhibited significantly larger size-at-age and faster developmental rate during 1 out of 3 experiments, possibly driven by metabolic compensation to elevated pCO2 via a corresponding decrease in routine swimming velocity. Furthermore, larvae had significantly larger otoliths at 2170 µatm pCO2, and a similar but non-significant trend also occurred at 1200 µatm pCO2, sug- gesting potential implications for hearing sensitivity. The lack of effect on most variables meas- ured in this study provides an optimistic indication that this large tropical species, which inhabits the offshore pelagic environment, may not be overly susceptible to ocean acidification. However, the presence of some treatment effects on growth, swimming activity, and otolith formation sug- gests the presence of subtle, but possibly widespread, effects of acidification on larval mahi-mahi, the cumulative consequences of which are still unknown.

Dos nematodos ascarididos son registrados para el Perú: Hysterothylacium pelagicum parasitando al pez perico o dorado (Coryphaena hippurus) colectado en un mercado de Lima y a Toxocara alienata encontrado en un pecarí de collar (Pecari tajacu) procedente de Iquitos. Así mismo, se realiza una descripción morfológica de los nematodos mencionados. Two ascaridoid nematodes are recorded by Peru: Hysterothylacium pelagicum parasitizing to common dolphinfish (Coryphaena hippurus) from a market of Lima and Toxocara alienata in a collared peccary (Pecari tajacu) from Iquitos. Likewise, it is made a morphological description of the nematodes.

The vertical movements of six adult male dolphinfish (Coryphaena hippurus) (95–120 cm estimated fork length), caught using standard sportfishing methods, were investigated using high-rate single-point pop-up satellite archival transmitters from 2005 to 2011 in the western central Atlantic. Data revealed a diel activity pattern within the mixed surface layer with dives below the thermocline suggesting temperature is not a barrier to vertical movements for short periods of time. Dolphinfish were tracked for periods of 4.96–30.24 day (Σ = 83.37 day), reaching depths >200 m, and in temperatures ranging from 16.20 to 30.87 °C. The six tags allowed comprehensive vertical movement analyses by time of day, duration at depth, and based on vertical movement patterns. The longest (>60 min), deepest (>30 m), and most extensive vertical movement patterns occurred during night rather than day, with the most time spent near the surface during the day. Dolphinfish spent 66 % of their time in the surface layer (0–9.9 m) and only one individual spent 8 % of the monitoring period diving >8 °C from the maximum surface temperatures recorded while tracked. Two tags were analyzed based on lunar phase and revealed contrasting relationships between vertical movements during new and full phases. Our results suggest dolphinfish vertically shift between surface and at-depth feeding strategies to exploit aggregating epipelagic and mesopelagic prey items leading to predictable diel vertical movements.

Fish stock assessment is a crucial tool for resource management. Small-scale fisheries are often multispecies and multigear. This study focuses on the search for patterns in the Ilheus small-scale fishery using landing data from 2000 to 2006 and climatic data. Ocyurus chrysurus and Ephinephelus spp. were the most commonly landed fish. The number of fishing trips was higher in the winter, when winds were weaker and temperatures lower. When the temperature increased, catches of Seriola dumerili were higher. Coryphaena hippurus and some rays were more abundant in the summer in the presence of stronger winds, intense rainfall and higher air temperature. Large catches of Lutjanus spp. and Scomberomorus spp. were obtained in the autumn. There is an annual seasonality in the fishery, with a cyclical landing pattern regardless of the years considered. These results are important in view of climate change, and specific strategies for better fisheries management are recommended.

Since the 17th century, the Tonnarella of Camogli, a small tuna trap, has been used to catch pelagic fish along the western coast of the Portofino Promontory (Ligurian Sea, Northwestern Mediterranean). The availability of long-term datasets on fish yields (1950–1974 and 1996–2011), with information related to the seawater temperatures and the North Atlantic Oscillation (NAO), has allowed us to study the qualitative and quantitative changes in fish yields in the last decade and the possible relationships with the seasonal anomalies of temperature that have occurred in the Ligurian Sea. In 1950–1974, yields remained relatively constant over time (average of 35.6 ± 8.7 t·year−1). From 1996 through 2011, yields were high (42.9 ± 15.9 t·year−1) but inconsistent with strong annual variability in catches. The primary catches are Seriola dumerili, Auxis rochei, Trachurus spp. and Sarda sarda. Changes in species composition have occurred as well: S. dumerili, Sardinella sp. and Belone belone have appeared recently. Moreover, a significant decrease in the boreal scombroid (Scomber scombrus) and an increase of warm-temperate carangids and other typically Southern Mediterranean species such as Coryphaena hippurus and Sphyraena viridensis, appear to be linked to the warming of the surface water layer, particularly evident in the Ligurian Sea, for the last 10 years. The analysis of this kind of trend may be a powerful tool for assessing structural changes of the pelagic fish community in the Ligurian Sea (Northwestern Mediterranean).

Since the industrial revolution, [CO2]atm has increased from 280 μatm to levels now exceeding 380 μatm and is expected to rise to 730–1,020 μatm by the end of this century. The consequent changes in the ocean’s chemistry (e.g., lower pH and availability of the carbonate ions) are expected to pose particular problems for marine organisms, especially in the more vulnerable early life stages. The aim of this study was to investigate how the future predictions of ocean acidification may compromise the metabolism and swimming capabilities of the recently hatched larvae of the tropical dolphinfish (Coryphaena hippurus). Here, we show that the future environmental hypercapnia (ΔpH 0.5; 0.16 % CO2, ~1,600 μatm) significantly (p

Made available in DSpace on 2019-10-06T15:42:47Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-01-01 Trophic relationships of large pelagic predators can determine the structure and dynamics of oceanic food webs. The feeding habits and trophic ecology of five large pelagic fish (Acanthocybium solandri, Coryphaena hippurus, Elagatis bipinnulata, Thunnus albacares and Thunnus atlanticus) in the Saint Peter and Saint Paul Archipelago were evaluated to determine whether there is a trophic-niche overlap or resource partitioning among them. Eighty prey items found in 1528 stomachs were identified and grouped into Cephalopoda, Cnidaria, Crustacea, Gastropoda, Teleostei and Tunicata. Exocoetidae and Scombridae were the main prey in the diet of Acanthocybium solandri. In C. hippurus, Cheilopogon cyanopterus and Exocoetus volitans were the most important prey items, whereas C. cyanopterus was the main prey for T. albacares. Thunnus atlanticus consumed a great proportion of invertebrate species, with shrimps of Sergestidae family being particularly important. The gastropod Cavolinia sp. was the most important prey for E. bipinnulata. The five species had a high trophic specialisation and a high trophic level (>4.4), whereas most dietary overlaps were consistently low. The most important factor for diet dissimilarity was the consumption of Exocoetidade. All species were classified as top predators with varied diets, indicating their structural and functional importance in the food web of the Archipelago. Laboratório de Oceanografia Pesqueira Universidade Federal Rural de Pernambuco, Rua Dom Manuel de Medeiros, s/n Fundación Colombiana Para la Investigación y Conservación de Tiburones y Rayas SQUALUS, Calle 10a 72-35 Laboratório de Elasmobrânquios e Nécton Marinho Universidade Estadual Paulista-UNESP/CLP, Praça Infante Dom Henrique, s/n Laboratório de Elasmobrânquios e Nécton Marinho Universidade Estadual Paulista-UNESP/CLP, Praça Infante Dom Henrique, s/n

O peixe-voador, Hirundichthys affinis, apresenta enorme importância socioeconômica, constituindo fonte de alimento e renda para comunidades pesqueiras em Caiçara do Norte, no Estado do Rio Grande do Norte. A produção de H. affinis é responsável por 41,9% da produção pesqueira local, representado o principal recurso pesqueiro desse município. Dados analisados da produção do peixe-voador nos anos de 1993 a 2010 indicaram que sua produção apresentou variações, impactando a produção pesqueira total de Caiçara do Norte. A produção de H. affinis em Caiçara do Norte ao longo de 17 anos em geral foi crescente. O número de embarcações pesqueiras não esta relacionado com as variações da produção do peixe-voador, H. affinis. As variações da produção de H. affinis estão possivelmente relacionadas com os fatores ambientais. Observou-se que não teve relação entre a produção de presa H. affinis e do predador peixe dourado, Coryphaena hippurus durante o período verificado. Essas informações subsidiam o manejo sustentável da espécie uma vez que este recurso pesqueiro isoladamente contribui com 38% da produção pesqueira do Rio Grande do Norte . Palavras-chave: pesca artesanal, recursos pesqueiros, peixe-voador, águas costerias. DOI: http://dx.doi.org/10.18561/2179-5746/biotaamazonia.v3n2p23-32

The seasonal distribution and abundance of larval fishes in the central and southern surface waters of the East Sea were investigated seasonally during 2011 and 2012. During the study period, the larvae of 39 species belonging to 26 families were collected. The most abundant species were Engraulisjaponicus, which accounted for 97.5% of the total number of individuals collected. Scomber japonicus, Clupea pallasii, Chromis notatus, Cottidae sp., and Coryphaena hippurus accounted for 1.7% of the total. The number of species, number of individuals, and species diversity indices fluctuated with the season. The peak number of species and individuals occurred in September and May, respectively. The larvae of the main species displayed a distinct spatial distribution and seasonal occurrence patterns. E. japonicus and C. notatus widely distributed throughout the study area. During summer and autumn, S. japonicus and C. hippurus were abundant in southern and offshore regions. C. pallasii occurred only in the southern region during winter. The seasonal occurrence and patterns of distribution of the larvae of main species seems were correlated with surface water temperature.

The timing and location of the 2010 Deepwater Horizon (DWH) incident within the Gulf of Mexico resulted in crude oil exposure of many commercially and ecologically important fish species, such as mahi-mahi (Coryphaena hippurus), during the sensitive early life stages. Previous research has shown that oil exposure during the embryonic stage of predatory pelagic fish reduces cardiac function - a particularly important trait for fast-swimming predators with high aerobic demands. However, it is unclear whether reductions in cardiac function translate to impacts on oxygen consumption in these developing embryos and larvae. A 24-channel optical-fluorescence oxygen-sensing system for high-throughput respiration measurements was used to investigate the effects of oil exposure, temperature and developmental stage on oxygen consumption rates in embryonic and larval mahi-mahi. Oil-exposed developing mahi-mahi displayed increased oxygen consumption, despite clear cardiac deformities and bradycardia, confirming oxygen uptake and delivery from a source other than the circulatory system. In addition to metabolic rate measurements, nitrogenous waste excretion was measured to test the hypothesis that increased energy demand was fueled by protein catabolism. This is the first study to our knowledge that demonstrates increased energy demand and energy depletion in oil-exposed developing mahi-mahi.

En Venezuela, el nororiente es la región pesquera más importante del país por la abundancia de sardina (Sardinella aurita) y otros recursos marinos cuya captura anual en conjunto supera las 300.000 tm. Sus aguas son fértiles por la existencia de una surgencia de aguas subsuperficiales y otros factores como la influencia de los grandes ríos suramericanos (especialmente el río Orinoco), las lagunas costeras y la presencia de islas. En la isla de Margarita se han estudiado las posibilidades del cultivo de unas 16 especies de peces marinos, pero hasta ahora solamente la paguara Chaetodipterus faber (Ephippidae) y el pámpano Trachinotus goodei (Carangidae) tienen las mejores posibilidades para su producción intensiva. Ambas especies alcanzan peso comercial (300-400 g) en menos de un año de cultivo, desarrollan las gónadas y desovan en confinamiento. En la paguara se ha logrado la reproducción controlada y el levante de juveniles, pero se debe optimizar el engorde. T. goodei es la especie de pámpano más resistente a las enfermedades y con relativo buen crecimiento. Se discuten las posibilidades reales del cultivo de ambas especies y limitantes que deben superarse. El éxito radica en utilizar un alimento seco apropiado para el engorde en instalaciones flotantes. También se aconseja cultivar especies de pargos Lutjanus en jaulas flotantes y masificar el levante de juveniles, así como iniciar experiencias con el dorado Coryphaena hippurus (Coryphaenidae) porque en el área se capturan adultos durante todo el año, lo cual facilitaría las actividades relacionadas con su reproducción y levante de juveniles. The northeast coast of Venezuela is the most important fishing region in the country, the sardines (Sardinella aurita) and other species abound in its waters, the annual catch exceeds 300.000 mt. Several factors account for this fertility: an upwelling of subsurface waters, the influence of great South American rivers (notably the Orinoco river), the coastal lagoons, and the presence of numerous islands. In the island of Margarita, the possibilities of cultivating 16 species of marine fishes have been studied, but so far only two species, the spadefish Chaetodipterus faber (Ephippidae) and the permit Trachinotus goodei (Carangidae) show any potential of intensive production. Both species reach their commercial weight (300 - 400 g) in less than one year, show gonadal maturity and spawn in confinement. For C. faber controlled reproduction and the raising of brood have been achieved but fattening should still be optimized. Trachinotus goodei is a very disease resistant species and grows relatively fast. In this paper we discuss the realistic possibilities of cultivation for both species, and the problems that must be solved. Success depends upon the use of adequate dry feed in floating cages in this installations. Experiments with snappers, Lutjanus, and dolphinfish, Coryphaena hippurus (Coryphaenidae), are recommended, because adults of these species are caught in this area all year round, which should facilitate all activities related with reproduction and the raising of juveniles.

Bull rays (Pteromylaeus bovinus) and Dolphinfish (Coryphaena hippurus and Coryphaena equiselis) were collected in Olhao (south of Portugal). These animals hosted multiple parasites, namely Caligus spp., and underwent a variety of treatments to remove them. Of all treatments tested, hydrogen peroxide showed the best results, although only concentrations above 100 ppm were effective in parasite removal. These high concentrations, however, proved to be highly toxic for the fish and led to the loss of some animals, especially those which had been handled before treatment. A total of 14 Bull rays were transported to Bolougne-Sur-Mer (France) by road and some animals were lost, which was attributed to excessive time in transit (>45 hr). In another transport, three Bull rays and 10 Dolphinfishes were moved to Stralsund (Germany) by road and air. The mechanical wounds suffered by one of the Bull rays during transport led to its death and, consequently, a deterioration of water quality in the tank containing two other conspecifics. This deterioration of water quality resulted in problems for the other two Bull rays, and one perished approximately 48 hr after arrival. The authors concluded that Dolphinfish can be transported with a low bioload for at least 27 hr, and Bull rays should not undergo transports longer than 35 hr. Special attention must be taken to injured animals, since this can lead to a decrease in water quality and consequently affect other animals in the same transport tank. Zoo Biol. 32:222–229, 2013. © 2012 Wiley Periodicals, Inc.

The variability of mesoscale circulation structures in the Gulf of Mexico (GOM) was examined using satellite altimeter data collected between 1992 and 2008, and linkages between ocean circulation and the spatial distribution of larval fish were assessed. The abundance and dis- tribution of the larvae of 5 pelagic fish taxa (Auxis spp., Euthynnus alleteratus, Thunnus thynnus, other Thunnus spp., and Coryphaena spp.) were estimated from surveys conducted by the National Oceanic and Atmospheric Administration National Marine Fisheries Service each spring between 1993 and 2007. We observed a tendency for higher northward extension of the Loop Current (LC) during spring each year, with maximum northern penetration in summer, although the exact location of the LC varied from year to year. Generally, higher total larval abundances occurred during years of high northward penetration in a region that was crossed by the LC during its excursions. However, the interannual variability of the LC was not mirrored in a general increase or decrease of larval fish densities in the water masses out of the LC front. Further, the results show that larvae of T. thynnus and Auxis spp. were more abundant within the boundaries of anticyclonic features (usually between 148 to 158 cm of sea surface height) and within GOM common waters, defined as the background waters in between the boundaries of mesoscale features. Our findings suggest that the position and strength of anticyclone mesoscale features in the GOM define a favorable spawning habitat for the species examined.

To evaluate the economic effects of bag limit and minimum size regulations, it is important to understand how anglers’ valuation of catch varies. Using a sportfishing demand model, we estimated angler willingness to pay (WTP) for groupers Epinephelus spp. and Mycteroperca spp., red snapper Lutjanus campechanus, dolphinfish Coryphaena hippurus, and king mackerel Scomberomorus cavalla by using data from a choice experiment survey with questions about fishing trips in the southeast USA. Beyond differentiating by species and the number of fish caught (second through sixth), our catch disposition model separately estimated angler WTP for one additional fish caught and kept, caught and released due to a minimum size limit, and caught and released due to a bag limit. Angler valuations of groupers, red snapper, and king mackerel were similar and more than five times the angler valuation of dolphinfish. For all species, the angler valuation decreased with each successive fish. For red snapper and groupers...

Mahi-mahi (Coryphaena hippurus) is a resilient pelagic species that could provide long-term highly productive fisheries. Using FAO data we document enormous increases (746%) in reported global mahi-mahi landings since 1950. Detailed mahi-mahi fisheries records are limited, but an observer program monitoring Costa Rica’s Pacific mahi-mahi pelagic longline fleet between 1999 and 2008 (n = 217 sets) provided a rare opportunity to quantify bycatch in these fisheries. Several sea turtles and sharks of global conservation concern were caught incidentally: olive ridley turtle (Lepidochelys olivacea; n = 1348, mean = 9.05 per 1000 hooks), silky shark (Carcharhinus falciformis; n = 402, mean = 2.96 per 1000 hooks), thresher sharks (Alopias sp.; n = 158, mean = 1.12 per 1000 hooks), green turtle (Chelonia mydas; n = 49, mean = 0.35 per 1000 hooks), and three other threatened sharks in small numbers. Pelagic stingray (Pteroplatytrygon violacea; a ray of low conservation concern) was also a common bycatch (n = 625, mean = 4.77 per 1000 hooks). Generalized linear models (GLMs) of catch rates showed increases in olive ridley turtles and decreases in mahi-mahi and silky sharks over the decade examined. The high hooking survival rates of olive ridley and green turtles in observed sets (95% and 96% respectively) suggest that widespread training of the fleet in careful gear removal and turtle release methods could be one effective bycatch mitigation strategy for these species. GLMs also provide evidence that closing the fishery during peak olive ridley nesting times (at least near nesting beaches), in combination with reduced gear soak times, could help minimize the fishery’s impacts on threatened bycatch species while still maintaining a productive fishery.

Environmental changes influence foraging behavior for most animals. Dolphinfish, Coryphaena hippurus, are epipelagic predators and have a cosmopolitan tropical to warm-temperate (>20°C) distribution. We simultaneously obtained the ambient temperature and the foraging behavior (i.e., swimming speed, depth and tailbeat acceleration) of dolphinfish, using an acceleration data-logger in May, September, October, November 2007, June 2008, May and July 2010 for 8 individuals. Although the dolphinfish spent a mean ± standard deviation of 43.4 ± 27.7% of their time at the surface (0–5 m), dive excursions from the surface (DES) were observed in all individuals and maximum DES depths ranged from 50.1 to 95.4 m. DES events resulted dives below the thermocline for these dolphinfish, and there was a significantly positive relationship between the isothermal layer depth (ILD) and DES depth. Our results demonstrate that dolphinfish avoided the rapid thermal change beyond the thermocline, and their prey is most likely found in the upper layers of the thermocline. Gliding behavior during the DES phase was also observed and dolphinfish gradually descended to deeper waters with gliding. The gliding time was longer when the ILD was deeper, and fish tended to dive deeper. We suggest that dolphinfish adopt gliding behavior to search a broader range of depths for prey, while minimizing energy use.

Our research aims to identify longline fishing gear modifications that can improve fishing selectivity and reduce incidental capture of non-target species. Catch rates and anatomical hook locations (AHL) were compared when using a 14/0 standard “control” circle hook with a 0° offset and an experimental “appendage” hook in a Costa Rican longline fishery. With the appendage, the maximum dimension of the appendage hook was increased by 10% and the minimum dimension of the hook by 19%. A total of 1,811 marine animals were captured during five fishing trips. By taxonomic groups, sea turtles represented the largest total catch (27%), followed by sharks (26%), rays (25%), mahimahi (Coryphaena hippurus) (12%), and tunas and billfish (10%). Non-target and discard species, such as rays and sea turtles, accounted for over half of the total catch. Catch per unit effort (CPUE; number of individuals per 1,000 hooks) was higher with control hooks compared to appendage hooks for all species’ categories except rays; appendage hooks caught 52% fewer sea turtles and 23% fewer tunas and billfish than standard hooks, which represents a significant reduction in bycatch of endangered and other species. No differences were found in the AHL for sea turtles, suggesting use of the appendage may not incur additional advantages regarding turtles’ post-release survivorship. Despite lower catch rates for marketable species, such as sharks and mahimahi, use of the appendage resulted in dramatic reductions in catch rates of sea turtles. The results suggest that large scale adoption of hooks with a significantly wider hook dimension could be an effective conservation measure to maintain marine biodiversity while allowing for continued fishing.

Pelagic fish that are distributed circumtropically are characterised by a low population structure level as a result of a high capacity for dispersion and large population sizes. Nevertheless, historical and contemporary processes, including past demographic and/or range expansions, secondary contact, dispersal, gene flow, and the achievement of large effective population sizes, may play a part in the detection of divergence signals, especially in the case of tropical pelagic species, whose distribution range depends strongly on the sea surface temperature. The connectivity and historical demography of Atlantic, Indian, Pacific and Mediterranean populations of dolphinfish (Coryphaena hippurus) was studied using partial sequences of the mitochondrial DNA NADH dehydrogenase subunit 1 (ND1). AMOVA analyses revealed significant inter-oceanic divergence with three phylogroups located in the Indo-Pacific, Eastern Atlantic, and Mediterranean Sea, the last one being the most divergent. However, it was not possible to clearly observe any genetic differentiation between the Indo-Pacific and Atlantic populations, as has been reported for most tropical pelagic species of tuna and billfishes. This supports the assumption of recent dispersal among basins facilitated by the actual continuous distribution of dolphinfish populations. Moreover, the lack of a divergence signal for populations separated by the Panamanian Isthmus reveals that genetic drift does not exert a strong influence on tropical pelagic species with large effective population sizes.

We assayed genetic variations at five microsatellite loci of dolphinfish captured at five sites in 2005 and eight sites in 2006 to detect genetic population structure of dolphinfish Coryphaena hippurus in the Gulf of California and surrounding waters. Results show high genetic variation, similar to other pelagic fishes with large populations. Pairwise FST values and hierarchical AMOVA detected subtle but significant spatial and temporal heterogeneity, mainly in samples of 2005 and some of 2006. However, Bayesian assignment analysis failed to detect genetic differentiation, which was also supported by the Mantel test and gene flow estimates among the sampled sites. This suggests that, despite the slight heterogeneity detected in this region, the dolphinfish forms a single panmictic population with high genetic variation and gene flow.

The relationship between pelagic fish and ocean temperature is cited in many studies, the majority of which investigate correlations of pelagic species and sea surface temperatures (SST). While appropriate for surface-associated species, this may not be accurate for deep-diving fishes. A different way to examine this relationship is to model spatial autocorrelation of fish species and temperatures at an appropriate range of depths. Spatial autocorrelation, the distance at which data are interdependent, is a potential descriptor of the patch size of an organism. Here we modeled spa- tial autocorrelation for 5 pelagic species that inhabit different depths in the Gulf of Mexico: dolphin- fish Coryphaena hippurus, wahoo Acanthocybium solandri, yellowfin tuna Thunnus albacares, swordfish Xiphias gladius, and bigeye tuna Thunnus obesus. Additionally, we modeled spatial auto- correlation for ocean temperatures at the surface, at 200, and 400 m. We hypothesized that autocor- relation distances will be greater for deeper water temperatures and for species that live at deeper depths due to greater homogeneity of deep waters over greater spatial ranges. Results show average distances of autocorrelation on the order of 55 to 60 km for wahoo and dolphinfish, 90 km for yel- lowfin tuna, and 135 to 145 km for swordfish and bigeye tuna; the same data for temperature were 75, 135, and 300 km for SST, and at 200 and 400 m depth, respectively. Autocorrelation distances of dolphinfish, wahoo, and yellowfin were correlated with that of of SST, while the autocorrelation dis- tance of swordfish and bigeye were correlated with that of temperatures at 200 m. Results suggest that autocorrelation distances may be useful as a proxy for habitat delineation.

We examined the feeding ecology and niche segregation of the ten most abundant fish species caught by longline operations off eastern Australia between 1992 and 2006. Diets of 3,562 individuals were examined. Hook timer data were collected from a further 328 fish to examine feeding behaviour in relation to depth and time of day. Prey biomass was significantly related to predator species, predator length and year and latitude of capture. Although the fish examined fed on a mix of fish, squid and crustacea, fish dominated the diet of all species except small albacore (Thunnus alalunga) which fed mainly on crustacea and large swordfish (Xiphias gladius) and albacore which fed mainly on squid. Cannibalism was observed in lancetfish (Alepisaurus spp.). Multidimensional scaling identified three species groups based on their diet composition. One group consisted of yellowfin tuna (T. albacares), striped marlin (Tetrapturus audax) and dolphinfish (Coryphaena hippurus); a second group consisted of bigeye tuna (T. obesus), swordfish and albacore; and a third consisted of southern bluefin tuna (T. maccoyii) and blue shark (Prionace glauca). Of note was the separation of mako shark (Isurus oxyrhynchus) and lancetfish from all other predators. Prey length generally increased with increasing predator length although even large predators fed on a wide range of prey lengths including very small prey. Overall, differences in prey type and size, feeding times and depths were noted across the range of species examined to the extent that predators with overlapping prey, either in type or size, fed at different times of the diel period or at different depths. Taken together these data provide evidence for feeding niche segregation across the range of oceanic top predators examined.

Critical gaps in our understanding of the distributions, interactions, life histories and preferred habitats of large and medium-size pelagic fishes severely constrain the implementation of ecosystem-based, spatially structured fisheries management approaches. In particular, spawning distributions and the environmental characteristics associated with the early life stages are poorly documented. In this study, we consider the diversity, assemblages, and associated habitat of the larvae of large and medium-sized pelagic species collected during 2 years of monthly surveys across the Straits of Florida. In total, 36 taxa and 14,295 individuals were collected, with the highest diversity occurring during the summer and in the western, frontal region of the Florida Current. Only a few species (e.g. Thunnus obesus, T. alalunga, Tetrapturus pfluegeri ) considered for this study were absent. Small scombrids (e.g. T. atlanticus, Katsuwonus pelamis, Auxis spp.) and gempylids dominated the catch and were orders of magnitude more abundant than many of the rare species (e.g. Thunnus thynnus, Kajikia albida ). Both constrained (CCA) and unconstrained (NMDS) multivariate analyses revealed a number of species groupings including: (1) a summer Florida edge assemblage (e.g. Auxis spp., Euthynnus alleterattus , Istiophorus platypterus ); (2) a summer offshore assemblage (e.g. Makaira nigricans, T. atlanticus, Ruvettus pretiosus, Lampris guttatu s); (3) an ubiquitous assemblage (e.g. K. pelamis, Coryphaena hippurus, Xiphias gladius ); and (4) a spring/winter assemblage that was widely dispersed in space (e.g. trachipterids). The primary environmental factors associated with these assemblages were sea-surface temperature (highest in summer-early fall), day length (highest in early summer), thermocline depth (shallowest on the Florida side) and fluorescence (highest on the Florida side). Overall, the results of this study provide insights into how a remarkable diversity of pelagic species spatially and temporally partition spawning within a region that is characterized by dynamic oceanography and strong habitat gradients.

1.This study compared the catch rates of targeted dolphinfish or mahimahi (Coryphaena hippurus), and sea turtles and other fish bycatch in a shallow-set Costa Rican longline fishery using 14/0 circle hooks with and without a 10° offset. The effect of hook offset on hooking location and injury in captured sea turtles, specifically if the hooking was external, in the mouth, or in the esophagus was also evaluated. 2.Results were compared from six trips totalling 33 876 hooks with squid (Dosidicus gigas) used as bait. In total, mahimahi catch-per-unit-effort (CPUE, expressed as number caught per 1000 hooks) was similar between hook types (CPUE∼52). 3.Olive ridley sea turtles (Lepidochelys olivacea) were caught on all 42 sets. In total, 640 olive ridley turtles were caught and released alive. There were no significant differences in the number of sea turtles caught between hooks with and without an offset (CPUE∼19) nor between hook type and anatomical hooking location, suggesting similar levels of injury for turtles caught on each hook type. 4.These data suggest that a 10° offset on 14/0 circle hooks does not confer any selective advantages over hooks with no offset with respect to capture rates of mahimahi, sea turtles, sharks, or pelagic stingrays in a shallow set pelagic longline fishery. Copyright © 2010 John Wiley & Sons, Ltd.

Muscle tissue was collected for stable isotope analysis (SIA) from the main fish predators and their fish and cephalopod prey from oceanic waters off eastern Australia between 2004 and 2006. SIA of δ15N and δ13C revealed that the species examined could be divided into three main trophic groups. A “top predator” group consisted mainly of large billfish (Xiphias gladius and Tetrapturus audax), yellowfin (Thunnus albacares), bigeye (T. obesus) and southern bluefin (T. maccoyii) tunas and sharks; with mako (Isurus oxyrinchus) the highest. Below this tier was a second group composed of mid-trophic level fishes including albacore tuna (Thunnus alalunga), lancet fish (Alepisaurus ferox), mahi mahi (Coryphaena hippuris) and ommastrephid squid. Underlying both groups was a grouping of small fishes including myctophids, small scombrids and nomeids as well as surface fishes including macrorhamphosids. These groupings were based largely on mean animal size which showed a positive linear relation to δ15N (r2 = 0.58). Some species showed significant ontogenetic variation in either δ15N (swordfish, lancet fish, yellowfin and albacore tuna) or δ13C (mako shark). We also noted a consistent latitudinal change in δ15N and δ13C at ~28°S for the top predator species, particularly albacore and yellowfin tuna. The differences were consistent with a change from oligotrophic Coral Sea to nutrient rich Tasman Sea waters. These differences suggest that predatory fishes may have extended residence time in distinct regions off eastern Australia.

Many species of tropical seabirds rely on subsurface predators such as tuna and dol- phins to drive prey close to the ocean's surface. We observed seabird foraging events from fishing vessels around the island of Oahu, Hawaii, to determine the prevalence and relative importance of different subsurface predators to seabird foraging. Sixty-nine seabird foraging events were observed, in 62 of which the presence and/or identity of subsurface predators could be determined. Of those 62, all but two involved subsurface predators and accounted for 99.8% of all foraging birds. Skipjack tuna Katsuwonus pelamis were the predominant (81%) subsurface predator involved in seabird feed- ing events, with odontocetes Stenella attenuata and Pseudorca crassidens (8%), mahimahi Coryphaena hippurus (6%), and yellowfin tuna Thunnus albacares (2%) being less common. Wedge- tailed shearwaters Puffinus pacificus and brown noddies Anous stolidus foraged in association with tuna schools more often than would be expected by chance alone. Red-footed boobies Sula sula, in contrast, did not associate with any subsurface predator in greater proportion than what would be expected by chance. Nine additional seabird species were observed foraging in association with sub- surface predators, but not in numbers large enough for statistical analysis. This study highlights the value of regional investigations able to uncover the variable nature of seabird-subsurface-predator associations. The finding that, in Hawaii, at least 2 species of seabirds showed tight dependence on tuna underlines the need for tuna fishery management to address the potential indirect ecological effects of fishing.

Dietary information obtained from stomach contents can provide a wealth of information on an animal’s ecology. Where animals are cryptic, such as the post-hatchling life history stage of a sea turtle, the ecological insight that dietary analyses can provide, may be otherwise unobtainable. Investigations into post-hatchling turtle stomach contents have found planktonic organisms, dominated by pelagic molluscs and crustaceans, hydrozoans, Sargassum and fish eggs. The nature of these dietary organisms provides evidence for the widely accepted hypothesis that, with the exception of the flatback turtle (Natator depressus), the post-hatchling stage of a sea turtle’s life history is pelagic and oceanic. As the majority of studies that have investigated the stomach contents of post-hatchling sea turtles have been conducted on loggerhead turtles (Caretta caretta) in the northern Atlantic and Pacific Oceans, insight derived from dietary investigations into post-hatchling ecology is biased. This study investigates the diet of post-hatchling green turtles (Chelonia mydas) and loggerhead turtles in the southwest Pacific Ocean. Stomach contents were obtained from 55 green and loggerhead post-hatchling turtles that had stranded or been consumed by Coryphaena hippurus. Our findings demonstrate that loggerhead and green post-hatchlings in the southwest Pacific share similar feeding ecology and feed on a variety of neustonic items that are indicative of an oceanic and pelagic existence. The dietary items consumed by both species investigated belong to similar taxonomic groups as those found in previous studies with species level distinctions occurring owing to the different geographical location.

Duarte-Neto, P., Lessa, R., Stosic, B., and Morize, E. 2008. The use of sagittal otoliths in discriminating stocks of common dolphinfish (Coryphaena hippurus) off northeastern Brazil using multishape descriptors. – ICES Journal of Marine Science, 65: 1144–1152. The shape of sagittal otoliths from the dolphinfish (Coryphaena hippurus) was studied to test the hypothesis that two stocks exist off the northeast coast of Brazil. In all, 82 sagittal otoliths were collected from fish caught by the artisanal fleet in two coastal regions of northeastern Brazil in December 2003 and April/May 2004. Several shape descriptors were determined [area, perimeter, rectangularity, circularity, eccentricity, fractal dimension (FD), and Fourier coefficients (FCs)] to evaluate the degree of similarity in the otoliths between regions. A three-morphotype pattern was revealed through cluster and principal component analyses based on FCs of the 30th harmonics. Apparently, this pattern is not influenced by clinal factors. Despite the great variability between otolith shapes, separation of the samples from two regions was suggested using multivariate and univariate analyses of variance for all shape descriptors and using canonical discriminant analysis. The methods successfully classified 57.1 and 69.6% of otoliths from the Maranhão and Rio Grande do Norte regions, respectively. The FD was a powerful descriptor in discriminating the two stocks. Differences in the shapes of sagittal otoliths may be related to different growth rates of the species and lend credence to the belief that there are two stocks along the Brazilian coast.

Exercise may cause an imbalance between pro-oxidants and antioxidants. In skeletal muscle, oxygen flow can increase considerably during vigorous exercise. The antioxidant system in athletes contributes to neutralize the concomitant rise in reactive oxygen species (ROS) production. The objective of this study was to compare the antioxidant system in muscle of three species of elasmobranchs and teleosts, considering differences in swimming capacity among species within each group and evolutionary differences between the two groups. Muscle samples were collected from elasmobranchs (Isurus oxyrinchus, Prionace glauca, Mustelus henlei) and teleosts (Totoaba macdonaldi, Kajikia audax and Coryphaena hippurus) in the coast of the Baja California peninsula, Mexico. The enzymatic activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione S-transferase (GST) was determined by spectrophotometry. The activity of the antioxidant enzymes CAT, GPx and GST was higher in elasmobranchs, as a group, than in teleosts. In fish species with high swimming capacities, P. glauca, K. audax and C. hippurus, antioxidant enzyme activity was higher in comparison with species with lower swimming capacities, M. henlei and T. macdonaldi. It is possible that antioxidant enzymes, particularly SOD, GPx and GST, contribute to avoidance of oxidative damage in teleost and elasmobranch species with higher swimming capacities. The antioxidant enzyme activities in fish appear to depend mainly on their swimming capacity and life style rather than the evolutionary group (elasmobranchs, teleosts).

Los patrones de estructura genetica en las poblaciones marinas estan asociados a una variedad de mecanismos de dispersion y de escalas espaciales. Las especies pelagicas migratorias, como el dorado Coryphaena hippurus, reafirman la nocion de un medio ambiente marino abierto y continuo. Muchos estudios han mostrado que las especies pelagicas oceanicas tienden a ser homogeneas geneticamente a grandes escalas geograficas, solo existiendo diferenciacion entre sus limites de distribucion o entre cuencas oceanicas. En este trabajo presentamos resultados que indican heterogeneidad genetica del dorado a escalas geograficas menores a las predichas por las generalizaciones anteriores. Patrones de restriccion (RFLPs) del gen mitocondrial NADH1 produjeron niveles de estructura genetica altamente significativos (ΦST = 0.029, P = 0.004, AMOVA) entre peces de Baja California Sur (BCS), Sinaloa y Hawai, consistentes con frecuencias haplotipicas heterogeneas (P = 0.014, prueba exacta de diferenciacion genetica) y con una menor diversidad molecular en los peces muestreados en BCS Patterns of genetic structure among marine populations involve a variety of dispersal mechanisms and spatial scales. Pelagic species, such as the dolphinfish Coryphaena hippurus, epitomize the open and continuous nature of the marine environment due to their extensive migrations. Many studies have revealed that oceanic pelagic species tend to be genetically homogeneous over local and often extended geographic scales and only show levels of differentiation among extreme localities or ocean basins. Here we present genetic data suggesting genetic heterogeneity in the dolphinfish at geographic scales much smaller than those predicted by those generalizations. Mitochondrial NADH1 gene RFLPs revealed a highly significant (ΦST = 0.029, P = 0.004, AMOVA) molecular genetic structure among fish from Baja California Sur (BCS), Sinaloa and Hawaii, consistent with heterogeneous haplotype frequencies (P = 0.014, exact test of genetic differentiation) and a depressed molecular diversity in fish sampled off BCS.

Dolphinfish (Coryphaena hippurus) samples were collected over four consecutive years from four locations in the eastern central Pacific to evaluate the genetic variation in a 751 bp segment of the mitochondrial NADH subunit 1 (ND1) to test for the presence of genetic population structure. Sequence analyses revealed no significant differences among collections from the same location in the different years sampled nor between locations. Mismatch distributions, estimations of population expansion parameters, and neutrality tests revealed significant fluctuations in population size in coincidence with past glacial and interglacial periods during the late Pleistocene. The low levels of nucleotide diversities and shallow coalescence of mtDNA genealogies observed were coincident with the estimated demographic parameters and neutrality tests, in suggesting the presence of important past population size fluctuations or range expansion. The prevention of the accumulated of deep lineages independantly on how it was originated, probably delayed the emergence of a population divergence process which might account for the lack of genetic differences detected. (c) 2006 Elsevier B.V. All rights reserved.

We conducted a displacement experiment to determine the influence of sensory cues on homing of pelagic fish to fish aggregation devices (FADs). If pelagic fish use chemical cues to home to a FAD, and cues such as odours from fouling organisms and fish associated with the FAD only occur down-current, we hypothesised that fish released down-current from a FAD would return in higher proportions than fish released across-current. Coryphaena hippurus (n = 161) and Seriola lalandi (n = 31) were caught from January to May in 2000, 2001 and 2002 within 50 m of a FAD and displaced to release sites 20, 75, 275 or 500 m across- or down-current. Overall proportions of return of C. hippurus to FADs varied among the 3 yr, with returns highest in 2000 (48.3%), lowest in 2001 (7.6%) and intermediate in 2002 (33%). There was a strong relationship between abundance of C. hippurus around FADs and current speeds, possibly due to a behavioural shift towards closer association with FADs during strong currents. This may have affected the proportions of return in different years, as currents were strongest in 2000 (0.46 m s-1 ± 0.06), weakest in 2001 (0.13 m s-1 ± 0.02) and intermediate in 2002 (0.30 m s-1 ± 0.09). Both C. hippurus and S. lalandi returned in proportions significantly higher than could be expected if fish swam in a random direction from the point of release, indicating a directed homing behaviour. Returns from down- and across-current release sites were similar at all distances for C. hippurus and S. lalandi, providing no evidence to suggest that these species used only chemical cues to home to FADs. As fish returned from up to 275 m away, sensory processes other than vision and olfaction must operate. Sound or vibrations from associated fish and the FAD are possible cues for homing.