Seriola Lalandi Research Articles

Southernmost records of two Seriola species in an Australian ocean-warming hotspot

Changes in marine species distributions in response to climate warming are being observed globally. However, there is great variation in the magnitude and rate of species responses. South-eastern Australia represents a global hotspot for ocean warming and, subsequently, numerous poleward extensions in marine species distributions are evident within the region. We report on two species of Carangid not previously found in this region, recorded through photo-verified observations by citizen scientists. This includes the first record of Amberjack (Seriola dumerili) in eastern Tasmania and an extension of the previously most southern reported observation of a similarly mobile congener, the Yellowtail kingfish (Seriola lalandi) along south-eastern Tasmania. Out-of-range observations may simply represent vagrant individuals; however, there is also evidence that they are often indicators of future colonisation potential. Moreover, the observations presented here are potentially representative of a range of climate-driven changes to marine biodiversity in this region and highlight the utility of community observations in acting as an effective early-warning system for reporting changes in the marine environment. Early detection and reporting of distributional changes are important for proactive environmental management, and is enhanced by establishing an informed community and mechanisms for conveying these observations to science and management authorities.

Morphometric and molecular descriptions of three new species of Hysterothylacium (Nematoda: Raphidascarididae) from Australian marine fish.

Three new species of Hysterothylacium Ward & Magath, 1917, including H. australe, H. kajikiae and H. brucei, from Australian marine fish are described and illustrated by light microscopy followed by genetic characterization of their first and second internal transcribed spacers (ITS-1 and ITS-2, respectively). This is the first study reporting ITS sequence data for adult Hysterothylacium spp. in Australia, which provides an insight into the identification of some of the Hysterothylacium larval types. Alignment of ITS sequences of these species with Hysterothylacium larval types previously reported in Australia showed that fourth-stage Hysterothylacium larval type XI from Seriola lalandi and third-stage Hysterothylacium larval type X from Sphyraene novae-hollandiae are identical with ITS sequences of H. australe, suggesting that these fish are natural intermediate/paratenic hosts of H. australe.

Long‐Term Dynamics in “Trophy” Sizes of Pelagic and Coastal Pelagic Fishes among California Recreational Fisheries (1966–2013)

AbstractIn California, recreational fisheries contribute a significant amount to coastal economies, with pelagic and coastal pelagic species constituting a principal set of target species during summer and fall. Although traditional catch frequency (landings) data sets exist for these species, size‐specific information is limited, especially for the largest size‐classes. We digitized weekly records of trophy catch reported in the “Whoppers of the Week” section of the Western Outdoor News, a California fishing and hunting newspaper published since 1953. The resulting database contained catch records that described the largest fish caught at each sportfishing landing site along the California coast during 1966–2013. We then assessed the temporal dynamics in trophy size of the top‐15 pelagic and coastal pelagic species, with a combined total of 21,440 individual catch records. Among the 15 pelagic and coastal pelagic species examined, the Yellowfin Tuna Thunnus albacares and Striped Bass Morone saxatilis were the only species that showed clear long‐term declines in trophy size over the study period, whereas the Pacific Bluefin Tuna Thunnus orientalis, White Seabass Atractoscion nobilis, and Yellowtail Jack Seriola lalandi exhibited long‐term increases in size. In general, the trophy sizes of pelagic species were more variable than those of coastal pelagic species and were not as consistently correlated with oceanographic conditions; both findings likely reflect the fact that oceanography drives the availability but not necessarily the size of pelagic species catch. In contrast, coastal pelagic species demonstrated trends in trophy sizes that were more consistently responsive to both oceanography and fisheries management. Our results suggest that oceanographic processes, natural history characteristics, fishing, and fisheries regulations each play a role in trophy size dynamics, but their relative influences vary among species.Received December 12, 2015; accepted April 26, 2016Published online August 3, 2016

Comparative assessment of TPHs and bioaccumulation in some fresh fish species in the Qua lbeo River of Eket of Akwa lbom State in Nigeria

This investigation was carried out in four different locations mapped out along the river bank. Twelve water samples were collected and six different fresh fish species that are frequently consumed were caught. They include: African red snapper (Lutjanus agennes), Yellow tail (Seriola lalandi), Barracuda (Sphyraena barracuda), Atlantic Croker (Micropogonias undulates), Catfish (Clarias gariepinus) and Tilapia (Oreochromis niloticus). Samples were subjected to screening using gas chromatography and flame ionization detector instrument. Results revealed presence of total petroleum hydrocarbon (TPH) contaminant in all the fish samples and varies with species significantly at p >0.05. The profound TPH compound is Nonane with molecular formula C9H20. 9 x 10-9 mg/l was adapted as Nonane concentration in water samples. Nonane concentration in fish samples showed African red snapper 3.9565±4.64648 mg/l, Yellow tail 8.7243±2.15546 mg/l, Barracuda 6.2555±0.48889 mg/l, Atlantic Croker 9.3866±0.42208 mg/l, Catfish 4.1973±1.52959 mg/l and Tilapia 6.0039±0.96487 mg/l respectively. The bioaccumulation factor varies in fish species, where the Yellow tail have higher bioaccumulation factor 969,369061, followed by Barracuda 695,067209, Tilapia 667,101072, Catfish 466,368366, African red Sniper 439,616275 and Crocker fish 104,2956024 respectively. This investigation reveal considerably the extent of bioaccumulation of TPH contaminants in aquatic animal models and making unsafe for consumption as some fishes bio-accumulate nonane beyond permissible limitBangladesh J. Sci. Ind. Res. 51(2), 147-154, 2016

Management of Sexual Maturation and Natural Spawning of Captive- Reared Yellowtail Kingfish, Seriola lalandi, in an Indoor Rearing Tank.

This study describes results on sexual maturation and characteristics of natural spawned eggs to develop a method for the production of stable, healthy fertilized eggs from captive-reared yellowtail kingfish, Seriola lalandi. A total of 59 yellowtail kingfish were captured off the coast of Jeju Island, after which the broodstock was cultured in indoor culture tank (100 m3) until they were 6.1–14.9 kg in body weight. As part of the rearing management for induced sex maturation, the intensity of illumination was maintained at 130 lux. The photoperiod (light/dark; L/D) was set to a 12 L/12 D from October 2013 to January 2014, and 15 L/9 D from February 2014 to June 2014. Feeds comprised mainly EP (Extruded Pellets), with squid cuttlefish added for improvement of egg quality, and was given from April to June 2014. The first spawning of yellowtail kingfish occurred in May 3, 2014, at a water temperature of 17.0°C. Spawning continued until June 12, 2014, with the water temperature set at 20.5°C. Time of spawning was 26 times at this period. The total number of eggs that spawned during the spawning period was 4,449×103. The buoyant rate of spawning eggs and fertilization rate of buoyant eggs during the spawned period were 76.1% and 100%, respectively. The diameters of the egg and oil globule were 1.388 ± 0.041 mm and 0.378 ± 0.029 mm, respectively, which was higher in early eggs than in those from late during the spawned period.

Morphological Development of Embryo, Larvae and Juvenile in Yellowtail Kingfish, Seriola lalandi.

This study monitored the morphological development of embryo, larvae and juvenile yellowtail kingfish, Seriola lalandi, for their aquaculture. The fertilized eggs obtained by natural spawning were spherical shape and buoyant. Fertilized eggs were transparent and had one oil globule in the yolk, with an egg diameter of 1.35 ± 0.04 mm and an oil globule diameter of 0.32 ± 0.02 mm. The fertilized eggs hatched 67–75 h after fertilization in water at 20 ± 0.5°C. The total length (TL) of the hatched larvae was 3.62 ± 0.16 mm. During hatching, the larvae, with their mouth and anus not yet opened. The yolk was completely absorbed 3 days after hatching (DAH), while the TL of post-larvae was 4.72 ± 0.07 mm. At 40 DAH, the juveniles had grown to 30.44 ± 4.07 mm in TL, body depth increased, the body color changed to a black, yellow, and light gray-blue color, and 3–4 vertical stripes appeared. At 45 DAH, the juveniles were 38.67 ± 5.65 mm in TL and 10.10 ± 0.94 mm in body depth. The fish were green with a light orange color, with 7 faint green-brown stripes on the sides of their body. At 87 DAH, the juveniles had grown to 236.11 mm in TL, 217.68 mm in fork length, and 136.5 g in weight. The fish resembled their adult form, with a light yellow-green body color, loss of the pattern on the sides of their body, and a yellow coloration at the tip of the caudal fin.

The effects of gonadotropin-releasing hormone analog on yellowtail kingfish Seriola lalandi (Valenciennes, 1833) spawning and egg quality

Communal spawning behaviour in marine aquaculture species often results in a few individuals contributing disproportionate amounts of gametes. This can lead to a reduction in genetic variability and increases the risk of inbreeding among successive generations. Therefore, long term sustainability of captive breeding programmes for such species partly depends upon maintaining a sufficiently high proportion of parents contributing high quality gametes during spawning. The current study was conducted to evaluate if the use of slow-release gonadotropin-releasing hormone analog (GnRHa) implants could increase the number of females spawning high quality gametes, and thus increase genetic variation in a captive population of yellowtail kingfish Seriola lalandi (Valenciennes, 1833). Broodstock fish received implants with or without 500μg of GnRHa during the spawning season. GnRHa treatment was associated with a higher proportion of females contributing to spawning. However, compared to eggs from non-GnRHa-treated broodstock, GnRHa significantly decreased the floating rate, fertilisation rate, number of viable eggs and egg oil globule diameter. Overall, the use of slow-release GnRHa implants is a useful tool to increase parental contribution to spawning, but this benefit must be carefully balanced against lower egg quality.

Assessment and comparison of proximate, fatty acid and mineral composition of six edible portions of South African cultured yellowtail (Seriola lalandi)

A whole fillet (A) and five distinct anatomical portions within a fillet (B–F) of South African farmed yellowtail were assessed for proximate, fatty acid and mineral composition. Within the whole fillet, moisture, protein, fat and ash accounted for 71%, 21%, 5% and 1% of the proximate composition respectively. Considerable inter-muscular variation in nutritional composition was observed, however, the dorsal section (portions B and D) was most representative of the proximate, fatty acid and mineral composition of the whole yellowtail fillet and may be used in future studies. High variability in mineral and essential fatty acid content was observed and no one portion could be considered to contain a superior nutrient complex. South African farmed yellowtail can be considered a semi-oily fish (5.3% fat) with relatively high levels of PUFA detected (PUFA > SFA > MUFA) primarily located in the dorsal and caudal sections. This study provided important information regarding the nutritional composition of South African reared yellowtail as well as recommendations regarding the sub-sampling of specific portions for future nutrient composition studies.

Growth, antioxidant capacity and muscle histochemistry of yellowtail kingfish (Seriola lalandi Valenciennes 1883): Selenium and temperature interaction

The aim of this study was to investigate the interactive effects of temperature and dietary selenium concentrations on antioxidant capacity, muscle histochemistry and the growth, of juvenile yellowtail kingfish (Seriola lalandi). The yellowtail kingfish were exposed to two temperatures (21°C or 26°C) and three selenium levels (0.0, 2.0 or 4.0mgSekg−1 of feed) for 30 days. Final weight and specific growth rate (SGR) were significantly affected by water temperature (ρ<0.001) and dietary Se (ρ<0.001) supplementation, and there were significant differences in the interaction between these two factors. Juvenile yellowtail kingfish fed Se-supplemented diets, attained a higher final weight and SGR than those without Se supplementation at 21°C, but not at 26°C. Regardless of the temperature, the red blood cell (RBC) glutathione peroxidase (GPx) activity of yellowtail kingfish fed Se-supplemented diets was significantly higher (ρ<0.05) than with the control diet. However, GPx activity of yellowtail kingfish when fed either 2.0mgSekg−1 or 4.0mgSekg−1 showed no significant difference (ρ>0.05). Se concentration in the muscles of juvenile yellowtail kingfish fed Se-supplemented diets was higher than that of the yellowtail kingfish that were fed the control diet. A histopathological test confirmed that 20.3% of fish muscles exhibited lesions, which occurred in the absence of dietary Se. The outcome of the present study helps in understanding the interactive effects of dietary Se concentrations and the temperature in the farming of yellowtail kingfish.

The effect of green and red light spectra and their intensity on the oxidative stress and non-specific immune responses in gold-striped amberjack, Seriola lalandi

The present study examined the effects of different light spectra (red and green light-emitting diodes [LEDs]) and light intensities (0.3 and 0.5 W m−2) on antioxidant systems (superoxide dismutase, H2O2 and lipid peroxidation) and immunity (lysozyme, melatonin and endorphin) in gold-striped amberjack, Seriola lalandi. In groups exposed to green LED, the levels of antioxidant enzyme were significantly lower than in the control, whereas the levels of immune-related parameters were significantly higher compared to other groups. The levels of antioxidant enzyme in individuals exposed to red light increased with increasing light intensity, whereas these levels were not correlated to the intensity of green light and were increased even at low light intensity. These results indicate that exposure to low-intensity green light accelerates the antioxidant system and immune system.

EFFECTIVENESS OF THE ANESTHETIC AQUI-S® 20E IN MARINE FINFISH AND ELASMOBRANCHS.

Immersion anesthetics are used in hatchery settings by veterinarians, field biologists, and laboratory researchers to aid in handling finfish for medical procedures, research purposes, and moderating perceived stress responses. The only Food and Drug Administration- (FDA) approved anesthetic for food fish, tricaine methanesulfonate, requires a 21-d withdrawal period prior to harvest. Ten percent eugenol (AQUI-S® 20E) has been gaining momentum for FDA approval because of its 0-d withdrawal time if fish are not of harvestable size within 72 h of exposure. We performed two trials to determine appropriate anesthetic doses for two cultured marine finfish: Atractoscion nobilis (white seabass, WSB) and Seriola lalandi (California yellowtail, YT). Fish were held in a treated water bath for 10 min or until opercular beat rate slowed to a rate of <2 beats/min. Based on these results, we conducted a field trial with wild Paralabrax maculatofasciatus (spotted bay bass), Paralabrax nebulifer (barred sand bass), Paralichthys californicus (California halibut), Triakis semifasciata (leopard shark), and Mustelus californicus (grey smooth-hound) at a single dosing regime, with animals held 5-10 min in anesthetic baths. Anesthetic dosing of 35-55 mg L(-1) provided relatively fast induction and good anesthetic maintenance in cultured and wild finfish. Anesthetic induction times were comparable among S. lalandi and A. nobilis at 35-mg L(-1) to 75-mg L(-1) doses, but recovery times were variable. Mortality rates of 20-90% were observed at higher doses (75 mg L(-1) and 100 mg L(-1), A. nobilis; 55 mg L(-1) and 75 mg L(-1), S. lalandi). The apparent increase in sensitivity of S. lalandi may have been associated with nutritional stress in the fish tested. There were no differences in time to anesthesia or recovery among wild finfish species tested at a single dose. Anesthetic induction, maintenance, and recovery were less predictable in the elasmobranch species tested and additional trials are needed to determine optimal dosing.

Combined TLR agonist and aeromonas antigens stimulation enhance the immune-related genes in yellowtail leucocytes

The purpose of this study was to characterize the TLR21 gene from yellowtail (Seriola lalandi) and its functional activity using TLR agonist stimulation and Aeromonas antigens. Basal TLR21 gene expression was analyzed in several tissues. Subsequently, the gene expression of TLR21 and IL-1β and TNF-α cytokines was evaluated in head-kidney leucocytes exposed to TLR agonists (CpGODN2006, LPS and Poly I:C) and then subjected to Aeromonas antigen stimulation. The yellowtail full-length cDNA sequence of SlTLR21 was 3615 bp (980 aa). The sequence showed a high degree of similarity with the counterparts of other fish species and shared the common structural architecture of the TLR family, including LRR domains, one C-terminal LRR region and a TIR domain. Gene expression studies revealed the constitutive expression of TLR21 mRNA in all the analyzed tissues, the highest levels being observed in spleen and head-kidney, where they play an important role in the fish immune system. Transcripts of TLR21 and the downstream IL-1β and TNFα cytokine genes were most strongly up-regulated after exposure to the TLR agonists, following Aeromonas antigen stimulation, suggesting they are involved in the immune response. The results indicate that TLR agonists, in combination with Aeromonas antigens in head-kidney leucocytes, synergistically enhance TLR21 and cytokines gene expression in yellowtail.

TLR21's agonists in combination with Aeromonas antigens synergistically up-regulate functional TLR21 and cytokine gene expression in yellowtail leucocytes

The purpose of this study was to characterize the TLR21 gene from yellowtail (Seriola lalandi) and its functional activity using TLR agonist stimulation and Aeromonas antigens. The TLR21 nucleotide sequence from yellowtail was obtained using the whole-genome shotgun sequencing method and bioinformatics tools. Basal TLR21 gene expression was analyzed in several tissues. Subsequently, the gene expression of TLR21 and cytokines IL-1β and TNF-α was evaluated in TLR agonist (CpG-ODN2006, LPS, and Poly I:C) exposing head kidney leucocytes, which were then subjected to Aeromonas antigen stimulation. The yellowtail full-length cDNA sequence of SlTLR21 was 3615 bp (980 aa) showing a high degree of similarity with the counterparts of other fish species and sharing the common structural architecture of the TLR family, including LRR domains, one C-terminal LRR region, and a TIR domain. Gene expression studies revealed the constitutive expression of TLR21 mRNA in all the analyzed tissues; the highest levels were observed in spleen and head kidney where they play an important role in the fish immune system. Transcripts of TLR21 and the downstream IL-1β and TNF-α cytokine genes were most strongly up-regulated after exposure to the TLR agonists following Aeromonas antigen stimulation, suggesting they are involved in immune response. The results indicated that TLR agonists, in combination with Aeromonas antigens in head kidney leucocytes, synergistically enhance TLR21 and cytokines in yellowtail.

Bacteria Pseudoaltermonas sp. con potencial probiotico para cultivos larvales de peces

Seriola lalandi is a pelagic marine species with high market demand national and internationally. However the larval survival in culture is low, which is attributed, among other factors, to the low quality of the larvae. The use of probiotic bacteria in appropriate amounts, in the larval culture of different organisms, has shown to improve the survival of the host. Based on this background our objective was to isolate and identify the bacteria from S. lalandi microbiota that show potential probiotic characteristics. For this purpose, 46 strains were isolated from S. lalandi juveniles and larvae, identified at the molecular level by analyzing the 16S rRNA gene. The following tests were performed as well: phylogenetic, antibacterial, hemolytic, proteolytic and lipolytic. The results showed that the total isolated bacteria, 42% belong to the genus Pseudoalteromonas , and nine presented inhibitory activity against pathogenic bacteria, of these, only one was negative for hemolysis, proteolysis and lipolysis. Based on the results, it is proposed to incorporate the bacteria Pseudoalteromonas sp. as potential probiotic adding it mixed with microalgae that are fed rotifers and artemia (vectors), which are traditionally used in the larval cultures of S. lalandi .

In-vitro and in-vivo biological activity of recombinant yellowtail kingfish (Seriola lalandi) follicle stimulating hormone

Biologically active recombinant yellowtail kingfish follicle stimulating hormone (rytkFsh) was produced in yeast Pichia pastoris and its biological activity was demonstrated by both in-vitro and in-vivo bioassays. Incubation of ovarian and testicular fragments with the recombinant hormone stimulated E2 and 11-KT secretion, respectively. In-vivo trial in immature female YTK resulted in a significant increase of plasma E2 levels and development of oocytes. In males at the early stages of puberty, advancement of spermatogenesis was observed, however plasma 11-KT levels were reduced when administered with rytkFsh.

Improving consumption rate estimates by incorporating wild activity into a bioenergetics model.

Consumption is the basis of metabolic and trophic ecology and is used to assess an animal's trophic impact. The contribution of activity to an animal's energy budget is an important parameter when estimating consumption, yet activity is usually measured in captive animals. Developments in telemetry have allowed the energetic costs of activity to be measured for wild animals; however, wild activity is seldom incorporated into estimates of consumption rates. We calculated the consumption rate of a free‐ranging marine predator (yellowtail kingfish, Seriola lalandi) by integrating the energetic cost of free‐ranging activity into a bioenergetics model. Accelerometry transmitters were used in conjunction with laboratory respirometry trials to estimate kingfish active metabolic rate in the wild. These field‐derived consumption rate estimates were compared with those estimated by two traditional bioenergetics methods. The first method derived routine swimming speed from fish morphology as an index of activity (a “morphometric” method), and the second considered activity as a fixed proportion of standard metabolic rate (a “physiological” method). The mean consumption rate for free‐ranging kingfish measured by accelerometry was 152 J·g−1·day−1, which lay between the estimates from the morphometric method (μ = 134 J·g−1·day−1) and the physiological method (μ = 181 J·g−1·day−1). Incorporating field‐derived activity values resulted in the smallest variance in log‐normally distributed consumption rates (σ = 0.31), compared with the morphometric (σ = 0.57) and physiological (σ = 0.78) methods. Incorporating field‐derived activity into bioenergetics models probably provided more realistic estimates of consumption rate compared with the traditional methods, which may further our understanding of trophic interactions that underpin ecosystem‐based fisheries management. The general methods used to estimate active metabolic rates of free‐ranging fish could be extended to examine ecological energetics and trophic interactions across aquatic and terrestrial ecosystems.

A comparison of the palatability of racemic praziquantel and its two enantioseparated isomers in yellowtail kingfish Seriola lalandi (Valenciennes, 1833)

The bitterness of racemic praziquantel (Rac-PZQ) constrains its use as an in-feed treatment against monogenean flukes in finfish aquaculture. Evidence exists in mammals that the R-(-) enantiomer of PZQ is less bitter than the S-(+) enantiomer. If fish exhibit this same response, then the recently described techniques for the large-scale resolution of R-(-)-PZQ from Rac-PZQ could facilitate the wide-spread application of this effective anthelmintic compound via feed. The hypothesis that yellowtail kingfish Seriola lalandi would find R-(-)-PZQ more palatable than Rac-PZQ and S-(+)-PZQ was tested in four trials. During the first three trials, the palatability of diets top-coated with 10 g kg-1 of Rac-PZQ or its two enantioseparated isomers were compared in small (85-160 g) and large (1.2 kg) yellowtail kingfish. A fourth trial compared the palatability of R-(-)-PZQ and Rac-PZQ at dietary inclusion levels of 2.5, 5.0 and 10.0 g kg-1 in small yellowtail kingfish (170 g). Ingestion data showed that R-(-)-PZQ to be no more palatable than either Rac-PZQ or S-(+)-PZQ to yellowtail kingfish, regardless of size. Indeed, evidence suggested that the S-(+)-PZQ to be slightly more palatable than both R-(-)-PZQ and Rac-PZQ. From these data, we hypothesize that the strong smell of R-(-)-PZQ (which was not present in S-(+)-PZQ) is an equally important determinant to palatability as taste in yellowtail kingfish. Results demonstrate that dietary inclusion level is a more important determinant to palatability than PZQ chirality; however, administration of R-(-)-PZQ may still be advantageous if it is demonstrated to be the only enantiomer efficacious against monogeneans.

Effects of taurine supplementation in live feeds on larval rearing performance of California yellowtailSeriola lalandiand white seabassAtractoscion nobilis

The larval rearing performance of California yellowtail (Seriola lalandi) and white seabass (Atractoscion nobilis) was compared between larvae fed taurine-supplemented rotifers (Brachionus plicatilis) and Artemia (Artemia franciscana) and control groups fed live feeds with no taurine enhancement. Results from the S. lalandi trial demonstrated that when fed taurine-supplemented rotifers, survival was significantly higher than the control group (20.1% vs. 9.1%, P < 0.01) as was notochord length (5.43 mm vs. 5.13 mm, P < 0.005). No larval performance differences were detected between experimental and control treatments of A. nobilis. Biochemical analyses demonstrated that taurine concentrations were significantly elevated in both S. lalandi (23.7 vs. 2.7 mg g−1, P < 0.001) and A. nobilis (33.0 vs. 21.0 mg g−1, P < 0.005) when live feeds were supplemented with taurine. Results suggest that taurine is a limiting nutrient in the larviculture of S. lalandi but may not be for A. nobilis.

The performance of larvalSeriola lalandi(Valenciennes, 1833) is affected by the taurine content of theArtemiaon which they are fed

This study describes the effects of feeding taurine-supplemented Artemia on the growth, survival, whole body taurine content and jaw malformation rate of larval yellowtail kingfish Seriola lalandi. Larvae were fed rotifers containing no supplemental taurine from 3 to 15 day post hatch (dph) and Artemia co-enriched with taurine from 12 to 22 dph. Artemia were supplemented at concentrations of either 0, 0.8, 1.6, 2.4, 3.2 or 4.0 g of taurine L−1 during the 18 h HUFA enrichment process. Taurine content in the Artemia increased from 0.76 ± 0.04% DW in those without supplementation to 3.95 ± 0.17% DW in those supplemented at 4.0 g L−1. Survival rates of larval yellowtail kingfish were significantly lower in all taurine-supplemented treatments compared to the unsupplemented control. Growth was significantly improved in those larvae fed taurine-supplemented Artemia; however, we cannot attribute this improvement solely to taurine, as improved growth may have been a function of the reduced survival, and therefore increased prey availability, in these treatments. The whole body taurine content of larvae fed unsupplemented Artemia was significantly lower (1.85 ± 0.03% DW) than those fed supplemented Artemia, which did not differ from each other (pooled average 2.48 ± 0.03% DW), suggesting either a functional excretion mechanism is in place or that this represents the saturation value for larvae of this age. Jaw malformation rates were not affected by Artemia taurine content. The results of this research suggest yellowtail kingfish larvae may have a lower requirement and/or a reduced tolerance to excess dietary taurine than juveniles.

Effects of MV Rena heavy fuel oil and dispersed oil on yellowtail kingfish early life stages

ABSTRACTThe grounding of the MV Rena has highlighted the lack of information concerning the effects of oil-related compounds on New Zealand marine life. Yellowtail kingfish (YTK), Seriola lalandi, embryos were exposed in static incubations to the water-accommodated fraction (WAF) of Rena heavy fuel oil as well as a similar preparation treated with the commercial dispersant Corexit 9500. Mortality in WAF treatments generally increased in association with total polycyclic aromatic hydrocarbon (tPAH) concentration over a 24-h period. Physical abnormalities were observed in some of the larvae exposed to WAF for 48 h. There was no survival in dispersed oil treatments after 24 h of exposure. These treatments had greater tPAH concentrations (2–53 µgL−1) than equivalent WAF dilutions (0.2–1.5 µgL−1 tPAH). Indications are that significant morbidity is induced in YTK at ecologically relevant tPAH concentrations. This highlights the need for further research into oil and dispersant toxicity in New Zealand marine species.