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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.

Dolphinfish are little known migratory fish targeted by sport, artisanal and commercial fleets. In this study, we analyzed a 10 year database of incidental catches of the tuna purse seine fleet in the Pacific Ocean off Mexico with the aim to understand the environmental determinants of the spatial distribution and seasonal migration patterns of dolphinfish. We modeled the probability of occurrence of dolphinfish as a function of spatial (geographical coordinates), temporal (month/year) and environmental variables (sea surface temperature [SST], chlorophyll [CHL] and sea surface height [SSH], inferred from satellites) using logistic Generalized Additive Models. Dolphinfish preferred waters with SST values from 23 to 28°C, low (

Windows of exposure to a weathered Deepwater Horizon oil sample (slick A) were examined for early life stage mahi-mahi (Coryphaena hippurus) to determine whether there are developmental periods of enhanced sensitivity during the course of a standard 96-h bioassay. Survival was assessed at 96 h following oil exposures ranging from 2 h to 96 h and targeting 3 general periods of development, namely the prehatch phase, the period surrounding hatch, and the posthatch phase. In addition, 3 different oil preparations were used: high- and low-energy water accommodated fractions of oil and very thin surface slicks of oil (∼1 μm). The latter 2 were used to distinguish between effects due to direct contact with the slick itself and the water underlying the slick. Considering the data from all 3 exposure regimes, it was determined that the period near or including hatch was likely the most sensitive. Furthermore, toxicity was not enhanced by direct contact with slick oil. These findings are environmentally relevant given that the concentrations of polycyclic aromatic hydrocarbons eliciting mortality from exposures during the sensitive periods of development were below or near concentrations measured during the active spill phase. Environ Toxicol Chem 2017;36:1887-1895. © 2016 SETAC.

The Deepwater Horizon oil spill in 2010 overlapped with the spawning of many pelagic fish species in the Gulf of Mexico, including mahi-mahi (Coryphaena hippurus). Polycyclic aromatic hydrocarbons (PAHs) released during the spill have been shown to cause photo-induced toxicity under ultraviolet (UV) radiation. In the present study, mahi-mahi embryos were exposed to high-energy water accommodated fractions of source and naturally weathered oils for up to 48 h. The timing of co-exposure with UV radiation varied between an early development exposure for 8 h or a late development exposure for 8 h. The UV co-exposure had a photo-induced toxic effect on hatching success for all oil types and exposure scenarios. A more sensitive developmental window to photo-induced toxicity was observed when UV exposure occurred late in development. Source Oil B (SOB) was over six fold more toxic and Massachusetts source oil (MASS) oil was 1.6 fold more toxic when the embryos were co-exposed to UV light late in development. Further, weathered oil from the surface (OFS) co-exposure with UV late in development resulted in bradycardia in the mahi-mahi. The present study provides evidence that the developmental window when UV co-exposure occurs has a significant effect on the degree of photo-induced toxicity of oil, as well as provides evidence that UV co-exposure may exacerbate long-term cardiac effects in developing fish. This article is protected by copyright. All rights reserved

The temporal and geographic attributes of the Deepwater Horizon incident in 2010 likely exposed pelagic game fish species, such as mahi-mahi, to crude oil. Although much of the research assessing the effects of the spill has focused on early life stages of fish, studies examining whole-animal physiological responses of adult marine fish species are lacking. Using swim chamber respirometry, the present study demonstrates that acute exposure to a sublethal concentration of the water accommodated fraction of Deepwater Horizon crude oil results in significant swim performance impacts on young adult mahi-mahi, representing the first report of acute sublethal toxicity on adult pelagic fish in the Gulf of Mexico following the spill. At an exposure concentration of 8.4 ± 0.6 µg L-1 sum of 50 selected polycyclic aromatic hydrocarbons (PAHs; mean of geometric means ± standard error of the mean), significant decreases in the critical and optimal swimming speeds of 14% and 10%, respectively (p

Dolphinfish Coryphaena hippurus support important commercial and recreational fisheries in the Gulf of Mexico. Understanding the feeding ecology of this economically important pelagic fish is key to its sustainable management; however, dietary data from this region are sparse. We conducted a comprehensive diet study to develop new trophic baselines and investigate potential ontogenetic and sex-related shifts in Dolphinfish feeding ecology. The stomach contents of 357 Dolphinfish (27.6–148.5 cm TL) were visually examined from fishery-dependent sources off Port Aransas, Texas. Our analyses revealed a highly piscivorous diet with Actinopterygii comprising 70.44% of the stomach contents by number. The most commonly observed taxa were carangid (12.45%N) and tetraodontiform (12.08%N; families Balistidae, Monacanthidae, and Tetraodontidae) fishes. Malacostracans were also common (24.83%N), mostly in the form of pelagic megalopae. Other prey categories included squid and the critically endangered Kemp’s R...

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.

Quality and shelf-life of whole and filleted Coryphaena hippurus, stored with modified atmosphere packaging (MAP) and natural antioxidants from halophytes (HAL), were investigated. Fillets were divided into control, simply sealed in trays; MAP, preserved by modified atmosphere (45% CO2, 50% N-2, 5% O-2); and MAP-HAL, pretreated with antioxidants and preserved by MAP. Whole and filleted fish were stored at -1 +/- 0.5 degrees C for 18days. The quality of the samples was analyzed at the time of packaging and after 3, 6, 9, 12, 15, and 18days. The MAP and MAP-HAL groups maintained the best sensorial profile, pH, and drip loss with respect to the untreated fillets. Higher levels of total volatile basic nitrogen (TVB-N) and oxidized proteins were observed in untreated samples with respect to the MAP and MAP-HAL groups. The principle component analysis revealed a different quality profile for untreated and MAP-treated fish.

Defining the oceanic habitats of migratory marine species is important for both single species and ecosystem-based fisheries management, particularly when the distribution of these habitats vary temporally. This can be achieved using species distribution models that include physical environmental predictors. In the present study, species distribution models that describe the seasonal habitats of two pelagic fish (dolphinfish, Coryphaena hippurus and yellowtail kingfish, Seriola lalandi), are developed using 19 yr of presence-only data from a recreational angler-based catch-and-release fishing programme. A Poisson point process model within a generalized additive modelling framework was used to determine the species distributions off the east coast of Australia as a function of several oceanographic covariates. This modelling framework uses presence-only data to determine the intensity of fish (fish km(-2)), rather than a probability of fish presence. Sea surface temperature (SST), sea level anomaly, SST frontal index and eddy kinetic energy were significant environmental predictors for both dolphinfish and kingfish distributions. Models for both species indicate a greater fish intensity off the east Australian coast during summer and autumn in response to the regional oceanography, namely shelf incursions by the East Australian Current. This study provides a framework for using presence-only recreational fisheries data to create species distribution models that can contribute to the future dynamic spatial management of pelagic fisheries.

The sampling of fish from the artisanal fleet operating with surface lines off north-eastern Brazil was carried out between 1998 and 2000. Generalized linear models (GLMs) were used to standardize mean abundance indices using catch and fishing effort data on dolphinfish Coryphaena hippurus and to identify abundance trends in time and space, using 1215 surface line deployments. A standard relative abundance index (catch per unit effort, CPUE) was estimated for the most frequent vessels used in the sets, employing factors and coefficients generated in the GLMs. According to the models, C. hippurus catches are affected by the operating characteristics and power of different fishing vessels. These differences highlight the need for standardization of catch and effort data for artisanal fisheries. The highest mean abundance values for C. hippurus were off the state of Rio Grande do Norte, with an increasing tendency in areas with greater depths and more distant from the coast, reaching maximal values in areas whose depths range from 200 to 500 m. The highest mean abundance values occurred between April and June. The higher estimated abundance of C. hippurus in this period off the state of Rio Grande do Norte and within the 200-500 m depth range may be related to a migration pattern of food sources, as its main prey, the flying fish Hirundichthys affinis, uses floating algae as refuge and to deposit its pelagic eggs.

The aim of this study was to investigate the role of the northern Gulf of Mexico (Gulf) as essential habitat of common dolphinfish (Coryphaena hippurus) and pompano dolphinfish (C. equiselis) during early life and to characterize conditions in which they were found. Eight ichthyoplankton surveys were conducted during the summer months from 2007 to 2010 in northern Gulf waters off Texas and Louisiana (26–28°N, 87–93°W), during which 1145 dolphinfish larvae were collected. C. hippurus, the dominant dolphinfish species, were collected in 57% of sampling sites with an overall mean density of 0.73 larvae 1000 m � 3 , whereas C. equiselis were only collected at 18% of sites with a mean density of 0.12 larvae 1000 m � 3 . Generalized additive models (GAMs) were used to examine the relationship between several environmental parameters and C. hippurus presence/absence and density. Both presence/absence and density GAMs indicated that catches of C. hippurus larvae increased near fronts and eddies and that increased abundances were most strongly associated with higher salinities and cooler temperatures. In addition, our models showed that C. hippurus larvae were positively associated with C. equiselis larvae, suggesting that C. hippurus and C. equiselis use similar habitats. Results of this study indicate that the Gulf may represent important spawning and/or nursery habitat of dolphinfishes and that mesoscale features and physicochemical conditions influence the distribution and abundance of C. hippurus larvae in this region.

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).

Using data from analyses of stomach contents and stable isotopes, we examined high-resolution variations in the feeding habits and trophic position of Dolphinfish Coryphaena hippurus during 2005–2007. In total, 418 specimens were collected off the southern Baja California peninsula, Mexico. Based on analysis of stomach contents (% index of relative importance [%IRI]), Dolphinfish consumed mainly epipelagic prey, with the red crab Pleuroncodes planipes as the most abundant prey species. The diet was highly similar between sexes but differed between size-classes: Dolphinfish smaller than 65 cm FL fed mainly on Pacific Sardine Sardinops sagax caeruleus (%IRI = 30), whereas those larger than 110 cm FL fed mainly on jumbo squid Dosidicus gigas (%IRI = 45) in addition to red crabs. Dietary differences between the smallest and largest specimens were mainly related to changes in morphology and spatial stratification by size (i.e., to avoid cannibalism). Trophic positions estimated by both methods indicate...

Annual ichthyoplankton surveys have been conducted in the Gulf of Mexico during spring since 1982 by the National Oceanic and Atmospheric Administration (NOAA) National Marine Fisheries Service (NMFS) Southeast Area Monitoring and Assessment Program (SEAMAP). Historically, ichthyoplankton has been assessed using bongo and surface neuston nets. A new sampling gear, the S-10 net, was tested between 2009 and 2011. This is a 1 × 2 m frame fitted with a 0.505 mm mesh net, towed in a yo-yo fashion between the surface and 10 m. Sampling effectiveness of the three gears was compared by examining the abundance and length of larvae of bluefin tuna (Thunnus thynnus) and seven co-occurring pelagic taxa (Auxis spp., Euthynnus alleteratus, Coryphaena spp., Katsuwonus pelamis, other Thunnus spp., family Istiophoridae, and Xiphias gladius) and vertical distributions of scombrid taxa were examined using MOCNESS samples. Permutational multivariate analysis of variance (PERMANOVA) of net type and time of sampling (day/night) indicated that net type was a significant factor in assessing abundance and length for all taxa. Highest abundances for seven of eight taxa were in S-10 samples, and MOCNESS samples confirm highest scombrid abundance between the surface and 20 m. Our results show sampling effectiveness strongly depends on the depth fished by the net and that the S-10 net was more effective than standard SEAMAP bongo and neuston nets. Thus, future sampling with the S-10 net may improve the annual index of larval abundance for the western population of Atlantic bluefin tuna, traditionally based on abundance from bongo samples.

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.

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...

An incident of foodborne poisoning causing illness in 53 victims due to ingestion of fish fillets occurred in January, 2009, in Kaohsiung city, southern Taiwan. The two suspected fish samples contained 11.3 and 37.7 mg/100 g of histamine, which is greater than the 5.0 mg/100 g allowable limit suggested by the United States Food and Drug Administration. Given the allergy-like symptoms of the victims and the high histamine content in the suspected fish samples, this foodborne poisoning was strongly suspected to be caused by histamine intoxication. Five histamine-producing bacterial strains capable of producing 1.23 to 36.48 ppm of histamine in trypticase soy broth (TSB) supplemented with 1.0% L-histidine (TSBH) were identified as Bacillus subtilis (four strains) and Enterobacter aerogenes (one strain) by 16S rDNA sequencing with polymerase chain reaction (PCR) amplification. Moreover, the fish species of suspected samples were identified as mahi-mahi (Coryphaena hippurus) by using PCR direct sequence analysis. PRACTICAL APPLICATIONS Based on the finding that high contents of histamine (>30 mg/100 g) were detected in the suspected mahi-mahi samples, we speculate the temperature abuse of the fillets before cooking contributed to the presence of high histamine levels in mahi-mahi fillets and resulted in foodborne poisoning. Although histamine-producing strains, Bacillus subtilis and Enterobacter aerogenes, were isolated from suspected fish samples, they might not be the main contributors to histamine accumulation because of low histamine production. These results re-emphasize proper handling temperature for seafoods and offer an important awareness that Coryphaena hippurus fillets could become a hazardous food item in causing histamine poisoning even though no quality deficiency was observed on the fillets.

The resting metabolic rates (R(R)) of western North Atlantic Ocean sciaenids, such as Atlantic croaker Micropogonias undulatus, spot Leiostomus xanthurus and kingfishes Menticirrhus spp., as well as the active metabolic rates (R(A)) of M. undulatus and L. xanthurus were investigated to facilitate inter and intraspecific comparisons of their energetic ecology. The R(R) of M. undulatus and L. xanthurus were typical for fishes with similar lifestyles. The R(R) of Menticirrhus spp. were elevated relative to those of M. undulatus and L. xanthurus, but below those of high-energy-demand species such as tunas Thunnus spp. and dolphinfish Coryphaena hippurus. Repeated-measures non-linear mixed-effects models were applied to account for within-individual autocorrelation and corrected for non-constant variance typical of noisy R(A) data sets. Repeated-measures models incorporating autoregressive first-order [AR(1)] and autoregressive moving average (ARMA) covariances provided significantly superior fits, more precise parameter estimates (i.e. reduced s.e.) and y-intercept estimates that more closely approximated measured R(R) for M. undulatus and L. xanthurus than standard least-squares regression procedures.

We examined diet, dietary niche width, diet overlap, and prey size-predator size relationships of blue marlins Makaira nigricans, dolphinfish Coryphaena hippurus, yellowfin tuna Thunnus albacares, and wahoos Acanthocybium solandri caught in the western North Atlantic Ocean during the Big Rock Blue Marlin Tournament (BRT) in 1998-2000 and 2003-2009 and dolphinfish captured outside the BRT from 2002 to 2004. Scombrids were important prey of blue marlins, yellowfin tuna, and wahoos; other frequently consumed prey included cephalopods (for yellowfin tuna and wahoos) and exocoetids (for yellowfin tuna). Dolphinfish diets included exocoetids, portunids, and conspecifics as important prey. Blue marlins and wahoos consumed relatively few prey species (i.e., low dietary niche width), while dolphinfish had the highest dietary niche width; yellowfin tuna had intermediate niche width values. Maximum prey size increased with dolphinfish size; however, the consumption of small prey associated with algae Sargassum spp. occurred across the full size range of dolphinfish examined. Most interspecific diet overlap values with dolphinfish were not significant; however, blue marlins, yellowfin tuna, and wahoos had significant diet overlap due to their reliance on scombrid prey. Prey types found in blue marlins, dolphinfish, and wahoos were more consistent among BRT years than prey found in yellowfin tuna. The prey of yellowfin tuna and wahoos collected during BRT years correlated with historic (early 1980s) diet data from North Carolina, the Gulf of Mexico, and the Bahamas. Based on principal components analysis, diets from several oceans clustered together for blue marlins, dolphinfish, yellowfin tuna, and wahoos. Although differences were found, the diets of each predator were largely consistent both temporally (e.g., over the past three decades in the Gulf Stream) and spatially (among oceans), despite potential effects of fishing or environmental changes.

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.

First and second generation (F1 and F2), laboratory reared juvenile Coryphaena hippurus were used in preliminary growth studies. Fish were stocked in circular tanks and fed a diet of chopped herring and squid. Initial size and age of fish used in these studies were as follows: 61 mm TL, 1.6 g, and 45 days old for F1 and 87 mm TL, 5.95 g, and 65 days old for F2. Mean size at 130 days of age was 560 mm TL and 1,305 g for F1 and 540 mm TL and 1,150 g for F2. Food conversion ratios were 3.05 and 2.9 4 for F1 and F2 fish, respectively.

Pelagic fishes were counted around four fish aggregation devices (FADs) moored between 3 and 10km offshore on the continental shelf off Sydney, Australia. Visual counts were made at FADs on 81 days periodically from April 1999 to April 2002. Surface water temperature and current speed were also measured at the FADs. Assemblages of fishes at FADs followed a seasonal pattern, however, biological and physical variables influenced seasonal structure greatly. Abundances at FADs were greatest in spring due to the appearance of large schools (100s to 1000s) of juvenile Trachurus sp. In contrast, diversity was far greater in summer and autumn, principally due to the appearance of schools (10s to 100s) of juvenile Coryphaena hippurus (Coryphaenidae), and other warm water species from January to May when water temperatures were >20° C. Short-term variability differed among species; C. hippurus fluctuated greatly among counts separated by 2-3 days, while Seriola lalandi (Carangidae) and Alutera monoceros (Monacanthidae) abundances were more stable, indicating greater residence times at FADs for these two species. Marked differences in fish assemblages occurred between times when predators were present and absent, with few small fishes being observed when piscivorous predators occurred at FADs, regardless of season. Furthermore, abundances of C. hippurus and A. monoceros were correlated with current speed, with greatest abundances observed when currents were strong and weak, respectively. The results indicated that much of the temporal variability in fish assemblages at moored FADs could be explained by biological and physical factors.

Two groups of 6 mahi-mahi fillets, one untreated and the other dipped in a suspension of Morganella morganii, were refrigerated at 7°C and sampled after 0, 2, 4, 6, 8, and 10 d of storage. Results were similar for both groups of fish. Total volatile base-nitrogen (TVB-N) reached 30 mg-N/100 g on d 3, at which time aerobic plate count (APC) reached 106 colony forming units (CFU)/g and odor scores reached 6 on a scale of 1 to 10 (10 very fresh and 1 very spoiled). Good correlation existed between TVB-N and odor intensity (r = 0.84), between TVB-N and the log10 APC (r = 0.71), and between odor and the log10 APC (r = 0.91). These results show that TVB-N can serve as a good indicator of chilled mahi-mahi quality.

Tropical seabirds have evolved a wide range of breeding regimes to fit with their local environment. The western Indian Ocean shows various oceanic situations, providing opportunities to link variations in breeding phenology with variations of the environment. The breeding seasons of seabirds at Europa Island (Mozambique Channel, western Indian Ocean) are analysed. Three oceanic, tuna-associated species (the sooty tern Sterna fuscata, the red-footed booby Sula sula, and Audubon's shearwater Puffinus lherminieri) breed during austral winter (June–October), whereas the red-tailed tropicbird Phaethon rubricauda breeds during austral summer (November–April). During winter, sea-surface temperatures are the lowest, subtropical waters are the closest to the island, and long-line catches of tunas are important. Thermal fronts occur during winter, in relation to the northward shift of subtropical waters. This is known to be favourable to tunas, and I suggest that the winter breeding of sooty terns, red-footed boobies and Audubon's shearwaters is because of an increase in the abundance of tunas. Geographic variations in the breeding phenology of sooty terns in the western Indian Ocean largely support the hypothesis that sooty terns take advantage of cool subtropical waters, when those waters are within their foraging range. The red-tailed tropicbird is a solitary forager, not associated with tunas. During the chick-rearing period, 40% of the mass of food brought to the chicks consists of dolphin-fishes Coryphaena spp. Those warm water, surface dwelling fishes are known to migrate in relation to sea-surface temperatures. Seasonal changes in the occurrence or vulnerability of dolphin-fish in the Mozambique Channel may have favoured a summer breeding regime in red-tailed tropicbirds at Europa Island. Further studies of the marine life of seabirds are needed to test these hypotheses and to learn more about the foraging ecology of tropical seabirds.

Superficial stellate cells of an unknown origin were detected on the epidermis of juvenile mahi mahi, Coryphaena hippurus L., up to 60 days of age. The cells occurred in large numbers, and were detected in both wild and cultured fish. International authorities were unable to identify the organism and there was no pathology associated with the presence of the cells on the skin. Because of the fine cytoplasmic interdigitations between the organism and the host cell, and the close ecological association with both wild and cultured juveniles examined, it was thought that the cells could possibly be highly modified skin cells. We report here that the spinous cells possess DNA sequences encoding 16S subunit ribosomal RNA genes distinct from those of mahi mahi, and also that restriction enzyme digests of genomic DNA from the spinous cells and from mahi mahi produced distinct patterns after electrophoretic separation. This suggests that the spinous cells are a bizarre commensal organism displaying a close physical and ecological association with the fish host.

The standard metabolic rates (SMRs) of 11 (1.395–4.125 kg) dolphin fish (mahimahi or dorado, Coryphaena hippurus) were measured at 25°± 0.5°C. Fish were prevented from swimming with neuromuscular blocking agents and force ventilated. Heart rates were determined simultaneously. SMRs (358–726 mg O2 h –1) were several times those of other similarly sized active teleosts such as salmonids, but close to those of tunas. Heart rates (84–161 beats min –1) were also high, but alike those of tunas under similar circumstances. As in tunas, the high SMR of dolphin fish may result from high osmoregulatory costs engendered by their large gill surface areas and/or other adaptations necessary for achieving exceptionally high maximum metabolic rates.

The Mahimahi Coryphaena hippurus has excellent potential for aquaculture due to its fast growth, good food conversion ratio, high fecundity with natural captive spawns, and high price. Using current technology, three crops a year could yield 288,000 kg/ha of water/yr with a potential profit of US $1,280,000/ha water/yr. Hatchery methods are now adequate for pilot-scale production, and two venture capital companies are pursuing this course. Significant improvement could be made in egg quality, plankton nutrition, plankton substitutes, disease control, reduced aggression, and weaning feeds. More research is needed to learn about digestive physiology, weaning behavior, and the effects of crowding on mahimahi health. Hatchery production is limited most often by the amount of grown out Artemia or yolk-sac mahi larvae provided for postlarval feeding. Problems that occur at the broodstock, hatching, first feeding, second feeding, third feeding, weaning, and early juvenile stages are discussed. Using the current technology, the cost of post-hatchery mahimahi is 33 cents per fry. This cost could be reduced to 6 cents per fry by successfully (consistently) weaning postlarvae from live feeds by 25 days.

Recent improvements in enriching Artemia make mahimahi culture possible without using copepods. Mahimahi survive better when cultured copepods Euterpina acutifrons are used, especially when the larvae are under stresses such as high stocking density, cold weather, or the rigors of metamorphosis. This study looked at some differences between copepods and enriched Artemia.This study tested stress resistance by holding postlarval (PL) mahimahi out of water in a hand net for varying periods of time. Recovery from this stress shock was higher in PLs whose diet was higher in docosahexaenoic acid (DHA). DHA appeared to play an important role in stress resistance. High eicosapentaenoate (EPA) or high HUFA did not confer stress resistance when DHA levels were low. Copepods contained higher levels of many essential amino acids in addition to higher levels of DHA compared with enriched brine shrimp. Larvae sickened by disease appeared to lose fat, including DHA, but they conserved DHA relative to other fatty acids. Even when sick, mahimahi larvae fed a copepod diet resisted stress better than larvae fed an enriched brine shrimp diet. Optimal Artemia enrichment levels of DHA for mahimahi have not been reached and this may explain why it has been difficult for others to raise this fish consistently. E. acutifrons is relatively easy to culture, but may not be practical for commercial hatcheries, due to low yield (less than 10 g per 100 L per week).

Live hatchery feeds were assayed for fatty acids (FA), amino acids (AA), and their ability to support growth and survival of larval and postlarval mahimahi Coryphaena hippurus at two different hatchery stages. Euterpina acuritrons copepods (C), mahimahi yolk-sac larvae (YSL), Artemia parthenogenica brine shrimp nauplii (BSn), A. parthenogenica juveniles (BSj), and Brachionus plicatilis rotifers (R) were assayed, using several enrichment media. There was little difference in AAs among feeds. Levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were about 10 times higher in YSL than in their feeds. This explains previous findings where first stage larval survival (0–9 days) was not affected by feed HUFA levels. Second stage survival was significantly higher when larvae were fed copepods. Enrichment with 100 ppm SuperSelco greatly improved the survival of larvae that were fed brine shrimp. The even higher omega-3 fatty acids found in copepods appear to be important for survival of larvae under more stressful conditions. Brine shrimp juveniles enriched with SuperSelco are a good food for postlarval mahimahi. Yolksac larvae of mahimahi are an even better food, promoting faster growth at less cost, for large scale mahimahi aquaculturists. Different batches of yolksac mahimahi larvae varied by a factor of 10 in their concentration of DHA, but always had the highest level of DHA as much as 40% of total fatty acids (FAs). These “high HUFA” batches of YSL also had the highest levels of EPA and total fatty acids. The data suggest that climate and broodstock age may have considerable influence on larval nutrition.

The myxosporean parasite Kudoa thyrsites (Gilchrist) is well recognised as a cause of flesh liquefaction post-mortem in several fishes from both hemispheres. The observation of this condition in cultured mahi mahi, Coryphaena hippurus L., in Western Australia led us to search for possible reservoirs of infection amongst the abundant clupeoid fishes of the area. Prevalent and severe infections were found in Sardinops sagax neopilchardus (Steindachner), which we consider to be a major reservoir host for K. thyrsites in south-west Australian coastal waters. The parasite occurred less frequently in Spratelloides robustus Ogilby, Sardinetla lemuru Bleeker and Engraulis austratis (Shaw) from the same waters. Infection was not detected in Hyperlophus vittatus (Castelnau), Etrumeus teres (De Kay) or Nematalosa vlaminghi (Munro), which may reflect differences in range or dietary composition. Engraulis japonicus (Temminck & Sehlegel) imported from Japan were also infected, but a single sample of E. mordax Girard from California contained only an equipolar Kudoa species. These records expand the known host range of K. thyrsites to 20 species in 10 families, and several of these host species appear to be major reservoirs of infection in certain locations. Flesh spoilage due to the liquefactive effects of the parasite could occur in any of these hosts, and was seen here in S. sagax neopilchardus, S. robustus and E. japonicus in association with mature spores. Detection of infection with ultra-violet light was found to be ineffective because a cellular host response was not mounted by the clupeoids.

Myoliquefaction occurred post-mortem in wild and cultured mahi mahi, Coryphaena hippurus L., stored on ice, and the flesh disintegrated upon cooking. The condition was associated with multifocal infection of muscle with Kudoa thyrsites (Gilchrist). Histiolysis is presumably due to enzymes excreted by the parasite, including collagenases, as the collagen fibres of the intermyotomal connective tissues were ruptured and hypochromatic. Myofibre changes were limited to hyaline degeneration and loss of myofibrillar detail. Kudoa thyrsites occurs commonly in Australian populations of the type host species, Thyrsites atun (Euphrasen), which represent a partly sympatric reservoir of infection for C. hippurus. The successful culture of C. hippurus may require selection of disease-free sites or use of filtered water supplies.

Pancreatic extract of adult dolphin Coryphaena hippurus was found to have a broad range of proteolytic activity with two peaks, one at pH 5–6 and another at pH 10, when casein was used as a substrate. Enzymes similar in activity to those of pepsin, trypsin, amylase, lipase and collagenase were detected in the extracts by the use of specific chromogenic substrates for each enzyme. The relationship between these enzyme activities, and the formulation of diets for culture of this species, is discussed.

Open-ocean mariculture might have considerable advantages in large-scale production over usual tank and closed-bay techniques. Most of the benefits would lie in the elimination of closed systems which require extensive power for water circulation and are subject to the rapid spread of chemical pollutants and disease. In tropical and subtropical waters pelagic sargassum is suggested as a medium for mariculture. Sargassum could be utilized in shallow water as cover, with the concomitant life forms (i.e. plankton, crustaceans, etc.) as a food supply for juveniles such as Coryphaena sp. Some benthic forms, molluska for example, might produce higher yields under cover of sargassum than on reefs or platforms. Studies could also be made on the relationship of seaweed to eels and turtles with a view towards developing culture methods. Deep water platforms might be based under the sargassum mass to eliminate pollution problems associated with nearby land masses. As a byproduct of mariculture, the sargassum would provide the basis for a local alginate extraction industry.

The effect of killing method of common dolphins aboard vessels on green pigment formation, and the microbiological survey of the green meat were studied. Eight bacterial strains which produced H2S in peptone iron agar at both 4 and 25°C were isolated from green meat samples. They constituted one strain of Alteromonas putrefaciens and seven strains of Proteus vulgaris. Discoloration occurred when each of the eight isolates was reinoculated in normal fillets at 4°C. The bleeding operation has little effect on reducing green discoloration of the dolphen meat. Discoloration of the meat could be prevented by icing the fish and keeping them cold until they could be filleted and frozen.

Eleven wild-caught dolphin fish (Coryphaena hippurus L.) from Florida waters and 16 of the same species from an experimental mariculture facility were examined for evidence of parasitic disease. Thirteen (48–1%) were found to be infected with parasites of the digestive tract. Adults of the digenean trematode Dinurus rornatus were present in the stomach and intestine. Invasive metacercarial stages of the same species were found encysted in the somatic musculature, pericardium and stomach wall. Metacercaria were associated with mild inflammatory cell infiltration of the musculature and gastric submucosa and, in one case, focal degeneration of the muscle fibres. In addition, invasive plerocercoidsof an unidentified cestode species occurred in the stomach and intestine of a moribund juvenile fish; the associated lesions included degeneration and ulceration of the gastric and intestinal mucosa, with haemorrhage and granuloma formation in submucosal tissues. These findings indicate that parasitic infection of the digestive tract can be a significant cause of disease in dolphin fish in Florida waters.

The length-weight relationship and condition factor of 420 dolphin-fish (Coryphaena hippurus) collected in Malta in 1974 were determined. The length-weight relationship for the size range investigated was similar to that reported for the fish from North America. The main food items were flying fish and other fish and crabs.

Dolphin caught by charter boats fishing over the Continental Shelf in 1961–63 were examined to determine food habits and sex ratios. Most important prey (listed according to percent of total prey weight) were: Exocoetidae (26%), Scombridae (22%), Carangidae(12%), Balistidae (9%), and Coryphaenidae (5%). Males constituted a significant majority (61%) of large dophin (801–1,275 mm fork length). Most (71%) small dolphin (450–600 mm) were females. Large dolphin of both sexes were generally captured in open water, while small female dolphin were usually associated with tide-lines (areas where current patterns cause accumulations of floating Sargassum and other flotsam). In 1963, tide-lines were infrequently encountered by charter boats. Decreased charter boat catches, increased abundance of young males in the fishery, and impaired foraging by small female dolphin resulted. We hypothesize that male dolphin (which are heavier than females of similar length) leave the sanctuary of the tide-line at an ear...

Parasites were studied from the gill and buccal areas of 145 dolphin, Coryphaena hippurus Linnaeus, caught in the Straits of Florida. Dolphin were infested with a digenetic trematode, Bathycotyl branchialis Darr, and copepods, Charopinopsis quaternius Wilson, Caligus belones Kroyer, C. bonito Wilson, C. coryphaenae Steenstrup and Lutken, C. patulus Wilson, C. productus Dana, C. quadratus Shiino, and Euryphorus nordmanni Milne-Edwards. Parasite-mix, incidence, and intensity of infestation increased with increase in host size except that Caligus bonito and Charopinopsis quaternius were not found on fish larger than 1,000 mm. No significant relationships were found between host sex and parasite-mix, incidence, and intensity of infestation. Seven pairs of parasite species showed either positively or negatively significant interrelationships. C. hippurus is a new host record for Caligus bonito, C. patulus and Bathycotyl branchialis.

The validity of age determinations from scales of dolphin (Coryphaena hippurus) captured off the North Carolina coast is established. Specimens were obtained from the local charter boat fishery. The greatest age of dolphin examined was 3 years. None of the 3-year-old fish and few of the 2-year-old fish were females. Predominance of males in age-groups II and III is believed to be caused by differential feeding habits of the sexes. Analysis of stomach contents indicates that older males may be more voracious feeders than older females; and, therefore, are more susceptible to capture by the hook-and-line fishery. Males are heavier than females throughout their complete length range. The body-scale relation is efficiently described by linear regression. Theoretical fish length at the time of scale formation was 93.75 mm. Growth in length of male and female dolphin was not significantly different. Rate of growth was independent of year of collection. Length at time of first annular formation was 653 ...

Field experiments were conducted in the northeastern Gulf of Mexico off Panama City, Florida to evaluate the feasibility of using man-made midwater structures for attracting pelagic game fish to improve sportfishing catch rates. Significantly greater catches of little tunny (Euthynnus alletteratus), king mackerel (Scomberomorus cavalla), and dolphin (Coryphaena hippurus) were made around experimental structure sites than in adjacent control areas when equal experimental fishing effort was used. Multiple structures attracted larger numbers of coastal pelagic bait fish and produced larger catches of pelagic game fish than single-structure units. The distance offshore or water depth of structure locations affected both the species of fish attracted and the number of fish caught. Charter fleet vessels fished around one of the experimental structures for several hours and reported total numbers of pelagic game fish caught and catch rates at least double those in “other areas” for that day.

North Carolina's dolphin fishery was surveyed in 1961 and 1962 to evaluate its importance to the offshore sport-fishing industry, and to develop suitable and reliable techniques for sampling a marine sport-fishery. As a prelude to the investigation, characteristics of the prominent offshore charter-boat fishery are described. Duration of the sport-fishing season, species captured, fishing methods, and economical aspects of the fishery are discussed. In 1961, catch-forms, personal enumerations, and interviews with dockmasters were used to estimate the catch of party boats, private boats, and transient charter boats. Catch by these boats was approximately 3,150 fish. The activity of resident offshore charter boats operating from the principal North Carolina ports was sampled by use of log books. Complete catch records were returned from 20% of the 90 resident boats that habitually frequented offshore waters. Ports were stratified for statistical treatment into five areas on the basis of proximity a...