Wild Caught Research Articles

Nutrient and fatty acid composition of cultured and wild caught gold-spot mullet Liza parsia (Hamilton, 1822)

The gold-spot mullet, Liza parsia (Hamilton, 1822) is a common mullet species that constitutes year round thriving fishery in the shallow coastal waters, estuaries, mangrove swamps and brackishwater lakes along the coast of India. Nutrient and fatty acid composition were analysed in cultured and wild caught L. parsia of different size groups. Fish were cultured with formulated pelleted feed in brackishwater pond at Nagayalanka (15.9450 N; 80.9180E), Andhra Pradesh, India. Wild samples of L. parsia were caught from the same region near Krishna River. The fishes were categorised into four size groups (<50 g, 50-100 g, 101-150 g and >150 g) from both sources. The moisture and ash content were higher (p<0.05) in wild fishes (75.85 and 1.39%) compared to cultured ones (72.96 and 1.29%). Cultured L. parsia had higher (p<0.05) crude lipid (2.12-8.73%) across all size groups compared to wild group which recorded crude lipid in the range of 0.67-3.10%. However, no significant change was observed for crude protein between wild and cultured fish. The quantities (mg 100 g-1 of fish muscle) of 18:2n-6 fatty acids were significantly (p<0.05) higher by 12 fold in farmed fish, whereas 20:4n-6 was higher (p<0.05) by two times in captive L. parsia. Significant (p<0.05) difference was observed in docosahexaenoic acid (DHA) content between the cultured and wild fish (108.60 and 89.90 mg 100 g-1, respectively) but not in eicosapentaenoic acid (EPA) (110.59 and 115.03 mg 100 g-1 respectively). The consumption of 100 g L. parsia fish which was above 100 g size of both wild and farmed could meet per day (250 mg) dietary needs of EPA and DHA.

ONRAB® oral rabies vaccine is shed from, but does not persist in, captive mammals

ONRAB® is a human adenovirus rabies glycoprotein recombinant vaccine developed to control rabies in wildlife. To support licensing and widespread use of the vaccine, safety studies are needed to assess its potential residual impact on wildlife populations. We examined the persistence of the ONRAB® vaccine virus in captive rabies vector and non-target mammals. This research complements work on important rabies vector species (raccoon, striped skunk, and red fox) but also adds to previous findings with the addition of some non-target species (Virginia opossum, Norway rats, and cotton rats) and a prolonged period of post vaccination monitoring (41 days). Animals were directly inoculated orally with the vaccine and vaccine shedding was monitored using quantitative real-time PCR applied to oral and rectal swabs. ONRAB® DNA was detected in both oral and rectal swabs from 6 h to 3 days post-inoculation in most animals, followed by a resurgence of shedding between days 17 and 34 in some species. Overall, the duration over which ONRAB® DNA was detectable was shorter for non-target mammals, and by day 41, no animal had detectable DNA in either oral or rectal swabs. All target species, as well as cotton rats and laboratory-bred Norway rats, developed robust humoral immune responses as measured by competitive ELISA, with all individuals being seropositive at day 31. Similarly, opossums showed good response (89% seropositive; 8/9), whereas only one of nine wild caught Norway rats was seropositive at day 31. These results support findings of other safety studies suggesting that ONRAB® does not persist in vector and non-target mammals exposed to the vaccine. As such, we interpret these data to reflect a low risk of adverse effects to wild populations following distribution of ONRAB® to control sylvatic rabies.

Increasing survival and growth in larval leopard coral grouper (Plectropomus leopardus) using intensively cultured Parvocalanus crassirostris nauplii

AbstractLeopard coral grouper, Plectropomus leopardus are a heavily exploited, high‐value fish commonly found in the Asian live reef food fish trade. In past decades, many attempts at the mass culture of various grouper species have been undertaken; however, their small mouth gape at first feed has resulted in very low survival when using traditional live feeds such as rotifers. The use of wild caught or extensively cultured copepods has yielded potentially promising increases in survival and growth, but overall survival to the juvenile stage remains low, making mass culture currently impractical. The current study sought to build on past developments in grouper culture and recent advancements in copepod culture technology by observing how growth and survival were influenced by the addition of intensively cultured copepods to the early diet of P. leopardus larvae. Six tanks of larvae, three replicates per treatment, were fed either eggs and nauplii of the calanoid copepod Parvocalanus crassirostris, at a starting density of 5 mL−1, and the rotifer Brachionus rotundiformis, at a starting density of 10 mL−1, or were fed only B. rotundiformis, at a density of 15 mL−1, starting on the evening of 2 days post‐hatch (dph) and continuing until 9 dph. After this initial period, all larvae were fed the same diet of rotifers, Artemia, and dry feed until the cessation of the trial at 21 dph. Larvae fed P. crassirostris in addition to rotifers had a significantly higher survival, 9.9 versus 0.5%, than those fed only rotifers. Growth was also significantly enhanced in larvae offered copepods. Larvae only fed rotifers were, on average, 1.5 mm shorter at 21 dph than those that had been fed copepods. More rapid development and the earlier onset of flexion were also noted in the larvae that were offered copepods. The use of intensively cultured copepods, in this study, increased survival tenfold over previous studies, with P. leopardus larvae fed wild‐caught copepods. The application of intensively cultured copepods to the early diet of P. leopardus, along with future research to evaluate late‐stage mortality issues, may facilitate commercial production of this species.

Food-web transfer of microplastics between wild caught fish and crustaceans in East China Sea

Plastic pollution, including microplastics (MPs), poses a global threat to environmental and human health. Studies on the transference of MPs along marine food webs are limited. In the present study, we investigated MP pollution in 11 wild fish species (193 individuals) and 8 wild crustacean species (136 individuals) captured from the Zhoushan fishing ground, off the East China Sea. The average abundance of MPs found in two main tissues, the gill and gastrointestinal (GI) tract, were 0.77 ± 1.25 and 0.52 ± 0.90 items/individual, respectively. The MPs we found were predominantly fiber-shaped, blue, and composed of polyester polymers. Our results suggest that MP pollution is ubiquitous in the East China Sea. We suggest that MPs are likely aggregated in the higher trophic level fish species throughout the marine food web. Furthermore, we suggest that marine organisms which occupy higher trophic levels might be suitable MP indicator species.

Occurrences, levels and risk assessment studies of emerging pollutants (pharmaceuticals, perfluoroalkyl and endocrine disrupting compounds) in fish samples from Kalk Bay harbour, South Africa

A comprehensive analysis of 15 target chemical compounds (pharmaceuticals and personal care product, perfluoroalkyl compounds and industrial chemicals) were carried out to determine their concentrations in selected commercially exploited, wild caught small and medium sized pelagic fish species and their organs (Thyrsites atun (snoek), Sarda orientalis (bonito), Pachymetopon blochii (panga) and Pterogymnus laniarius (hottentot)) obtained from Kalk Bay harbour, Cape Town. Solid phase extraction (SPE) method based on Oasis HLB cartridges were used to concentrate and clean-up the samples. Liquid chromatography–mass spectrometry analysis of these chemical compounds revealed the simultaneous presence of at least 12 compounds in different parts of the selected fish species in nanogram-per-gram dry weight (ng/g dw) concentrations. The results revealed that perfluorodecanoic acid, perfluorononanoic acid and perfluoroheptanoic acid were the most predominant among the perfluorinated compounds and ranged between: (20.13–179.2 ng/g), (21.22–114.0 ng/g) and (40.06–138.3 ng/g). Also, diclofenac had the highest concentration in these edible fish species out of all the pharmaceuticals detected (range: 551.8–1812 ng/g). The risk assessment values were above 0.5 and 1.0 for acute and chronic risk respectively which shows that these chemicals have a high health risk to the pelagic fish, aquatic organisms and to humans who consume them. Therefore, there is an urgent need for a precautionary approach and the adequate regulation of the use and disposal of synthetic chemicals that persist in aquatic/marine environment in this province and other parts of South Africa, to prevent impacts on the sustainability of our marine environment, livelihood and lives.

Dispersal of the Mosquito Aedes vigilax (Diptera: Culicidae) From Urban Estuarine Wetlands in Sydney, Australia.

Aedes vigilax (Skuse) is a pest and vector species associated with coastal wetlands and the abundance of this mosquito has been identified as contributing to increased risk of mosquito-borne disease outbreaks. As urban development continues to encroach on these coastal wetlands, pest and public health impacts are becoming of increasing concern and in the absence of broadscale mosquito control. Urban planners are looking to buffer zones and other land use planning options to minimize contact between mosquitoes and humans but gaps in the understanding of dispersal ranges of mosquitoes hamper the adoption of these strategies. A mark-release-recapture experiment was conducted to measure the dispersal of this mosquito from an urban estuarine wetland in Sydney, Australia. An estimated total of over 150,000 wild caught female mosquitoes were marked with fluorescent dust and then released. A network of 38 traps was then operated for 5 d within an area of 28 km2. A total of 280 marked mosquitoes was recaptured, representing less than 1% of the estimate 250,000 marked mosquitoes released. Marked mosquitoes were recaptured up to 3 km from the release point, providing an insight into the dispersal range of these mosquitoes. The mean distance traveled by marked mosquitoes was 0.83 km, a result reflecting the greater proportion of marked mosquitoes recaptured near release point. The findings of this study indicate that effective buffer zones between estuarine wetlands and high-density urban developments would be an impractical approach to minimizing pest and public health impacts associated with this mosquito.

Consequential analysis of algal biofuels: Benefits to ocean resources

Ocean resources have been exploited at unprecedented rates, leading to marine biodiversity loss, food web changes, and other alterations of ocean ecosystem functions and structures. The capture of wild fish for human consumption and fishmeal are the primary drivers. Microalgae oil has long been investigated for biofuel production. Its co-product, defatted microalgal biomass, has potential to replace fishmeal from wild fish catch and thus mitigate ocean resource depletion.This study develops a new indicator for assessing consequential impacts on ocean resources in life cycle assessment. The indicator is based on primary production required, a concept previously used in ecological assessments and life cycle assessments to evaluate ecological impacts of fisheries and aquaculture. We estimate the primary production required for fishmeal production from the ocean (166 kg carbon/kg fishmeal), and the potential of defatted microalgae biomass displacing fishmeal. Results show that defatted microalgae biomass can lead to highly variable, but potentially significant, reductions in ocean resource demand. The variability is a function of the potential for replacement, which depends on the cultured fish species considered. As an example of this significance, based on available data for estimating the potential for defatted microalgal biomass to displace fishmeal for cultured tilapia, salmon, shrimp, carp, flounder, yellowtail and cod, by 2020 net primary production demand from the ocean could be reduced by approximately one billion tons of carbon.

The impact of coastal degradation on mangrove ecosystem in North Karawang coastal area

Coastal degradation can be observed as destruction of mangrove area. The impact of mangrove destruction is evidenced by a significantly eroded area. Further impacts included lessened biodiversity, especially in the mangrove ecosystem. This study aimed to determine the impact of coastal damage to the mangrove ecosystem in Karawang coastal areas. The mangrove degradation was identified from changes in mangrove covered area by utilizing data from several Landsat TM satellite imagery and ground check equipped with GPS and Google Earth applications. Data from the inventory of mangrove area issued by the Perhutani of KPH Purwakarta 2017 were also used as supplement in determining the extent of destruction. From satellite imagery, the mangrove area in 2017 was 258 hectares. This area was only approximately 3% of the total area of mangrove protected areas assigned by the Regency Spatial Plan. Compared to the condition in 2009, the coastal destruction was significant. The worst mangrove degradation occurred in the sub-districts of Cibuaya, Tempuran, and Cilamaya Wetan. The coastal communities were aware of the problem. They understood that this problem was caused by coastal abrasion and land use change, wild catch, milkfish and shrimp aquaculture, salt ponds, rice farms, and tourism.

Monitoring Seasonal Activity and Damage Potential of the Carob Moth Ectomyelois ceratoniae (Lepidoptera: Pyralidae: Phycitinae) in Citrus Orchards of the Western Cape Province

The carob moth, Ectomyelois ceratoniae (Zeller), is a polyphagous pest in hot and dry climates, such as the Mediterranean region, and occurs on citrus in South Africa, however, its pest status is not known. The aim of this research was to investigate its seasonal activity patterns and damage potential on citrus crops, in comparison to a pest of phytosanitary concern and one it can be confused with in the larval stage, the false codling moth, Thaumatotibia leucotreta (Meyrick). The study was carried out over 20 months in two regions, one with predominantly citrus and one with mixed agricultural production. Carob moth activity patterns indicated two periods of activity (summer and early spring), with damage taking place in citrus during autumn, close to harvest. The results showed that there were no significant differences in carob moth trap catches between the two study sites (F1,4 = 0.00661, P = 0.94) and no significant differences in wild false codling moth catches between the two study sites (F1,4 = 1.2960, P = 0.32). While traps in both regions caught carob moths in equal abundances, damage only occurred in the region dominated by citrus crops. Assessing pest status, relative to the false codling moth, indicated that carob moth is not currently a major economic pest.

Potential economic impacts of global wild catch fishery decline in Southeast Asia and South America

This paper examines the economy-wide impacts of wild catch fishery decline due to climate change on major wild catch producing countries in Southeast Asia and South America, particularly focusing on food industries. A global economic model has been extended to separate the choice between wild catch and aquaculture in the production and consumption functions. The fish commodity/sector is also disaggregated in the database into wild catch and aquaculture commodities/sectors in order to make it compatible with the modified model. Results show that the Philippines, Thailand, Malaysia, Indonesia, Ecuador and Peru experience considerable impacts on their economies, food industries, and households. Vietnam experiences the lowest impact on their economy because of low impact on their ocean fish resource. Results also indicate that expansions in aquaculture outputs are not adequate to compensate losses in wild catch production in all countries, and there will be a scarcity of fish in the international market that will be harmful to international trade of wild catch and aquaculture, as well as global food security. Households will also be substantially vulnerable due to high prices of fish and lower income levels resulting from contractions of production levels.

Survivorship of wild caught Mepraia spinolai nymphs: The effect of seasonality and Trypanosoma cruzi infection after feeding and fasting in the laboratory

Chagas disease is caused by Trypanosoma cruzi. Vector survival is an important variable affecting vectorial capacity to determine parasite transmission risk. The aims of this study are to evaluate vector survival under fasting/starvation conditions of wild-caught Mepraia spinolai after feeding and fasting, the pathogenicity of T. cruzi infection, the parasite burden and seasonal variation in parasite discrete typing units (DTU). The survivorship of M. spinolai nymphs after two continuous artificial feedings was evaluated, assessing their infection with microscopic observation of fecal samples and PCR. Later, insects were fasted/starved until death. We performed qPCR analyses of parasite load in the fecal samples and dead specimens. T. cruzi genotyping was performed using conventional PCR amplicons and hybridization tests. Infection rate was higher in M. spinolai nymphs in summer and spring than in fall. Parasite burden varied from 3 to 250,000 parasites/drop. Survival rate for starved nymph stage II was lower in insects collected in the spring compared to summer and fall. TcII was the most frequent DTU. Mainly metacyclic trypomastigotes were excreted. We conclude that M. spinolai infection rate in nymphs varies among seasons, suggesting higher transmission risk in warmer seasons. However, nymphs stage II collected in spring are more sensitive to starvation compared to other seasons. TcII in single or mixed infection does not seem relevant to determine vector pathogenicity. These results of vector survivorship after fasting/starvation are important to determine the competence of M. spinolai as a vector of T. cruzi, since they excrete metacyclic trypomastigotes and the parasitism with T. cruzi seems to be poorly pathogenic to the vector under a severe fasting/starvation condition.

On the half-life of thiocyanate in the plasma of the marine fish Amphiprion ocellaris: implications for cyanide detection.

The illegal practice of using cyanide (CN) as a stunning agent to collect fish for both the marine aquarium and live fish food trades has been used throughout the Indo-Pacific for over 50 years. CN fishing is destructive to all life forms within the coral reef ecosystems where it is used and is certainly one of many anthropogenic activities that have led to 95% of the reefs in the Indo-Pacific being labeled at risk for degradation and loss. A field-deployable test for detecting fish caught using CN would assist in combating the use of this destructive practice, however, no reliable and robust test exists. Further, there is little toxicokinetic data available on marine fish to support the development of such a test, yet such data is critical to establishing the concentration range and time scale over which such a test would be viable. This study presents the first direct measurement of the half-life of the metabolite thiocyanate (SCN) after pulsed exposure to CN in a marine fish. SCN was measured in the plasma of Amphiprion ocellaris after exposure to 50 ppm CN for three exposure times (20, 45, and 60 s) using HPLC-UV and a C30 column pre-treated with polyethylene glycol. Plasma SCN levels observed are dose-dependent, reflecting a longer time for conversion of CN to SCN as the dose of CN increases. SCN plasma levels reached a maximum concentration (1.2–2.3 ppm) 12–20 h after exposure to CN. The half-life for the elimination of SCN was 1.01 ± 0.26 days for 45 s exposure and 0.44 ± 0.15 days for 20 s exposure. Fish were also directly exposed to SCN (100 ppm for 11 days) and the observed half-life for SCN elimination was 0.35 ± 0.07 days. Plasma SCN levels did not return to control levels, even after 41 days when exposed to CN but did return to control levels after 48 days when exposed to SCN. The similar half-lives observed for CN and SCN exposure suggests that SCN exposure can be used as a proxy for measuring the rate of SCN elimination following CN exposure. In order for plasma SCN to be used as a marker for CN exposure, these results must be extended to other species and endogenous levels of SCN in wild caught fish must be established.

Hemodynamic Responses to Ventricular Pacing in the Fish Heart Depend on Repolarization Duration at the Paced Regions

IntroductionSpatiotemporal distribution of myocardial action potential durations is heterogeneous but a role of these heterogeneities is largely unknown. Heart ventricular contraction needs muscle mechanical heterogeneity, namely activation spread from “slow” to “fast” muscle elements, which are expected to have longer and shorter action potentials, respectively. We hypothesized that the longer repolarization duration at the primary activation area provides the better pump function. The objective of the present study was to evaluate an association between the repolarization duration in the area of initial activation and aortic blood flow under electrical pacing of different ventricular regions. Having a single ventricle and primitive, if any, conduction system, a fish heart presents a useful model for assessing the functional significance of electrophysiological nonuniformities.MethodsExperiments were performed in wild caught Atlantic cod (n = 18). Ventricular unipolar electrograms were led from an epicardial sock and intramural plunge electrodes (24–64 leads simultaneously) connected to a custom‐made mapping system. In each lead, activation times (ATs) and repolarization times (RTs) were determined as dV/dt min during QRS complex and dV/dt max during T wave, respectively. Activation‐repolarization intervals (ARIs, surrogate for action potential durations) were calculated as ARI = RT‐AT. Aortic blood flow was measured with transit time flow meter.ResultsIn sinus rhythm, the posterior wall near the atrioventricular junction was earliest to be activated (median ATs 9 [IQR 3–15] ms) and had the longest median ARIs (516 [IQR 430–580] ms). The most remote from this area regions had expectedly longer ATs (heart apex: 33 [IQR 29–44] ms; anterior base 33 [IQR 25–43] ms; both p<0.05 vs posterior wall) and also demonstrated shorter ARIs (heart apex: 482 [IQR 427–544] ms; anterior base 416 [IQR 390–497]; both p<0.05 vs posterior wall). Posterior wall pacing yielded a highest median aortic flow 47.3 [IQR 40.4–74.4] mL/min/kg. Apical and anterior basal pacing gave lower median aortic flow values (40.7 [IQR 29.0–49.2] and 29.7 [29.3–39.1] mL/min/kg, respectively; both p<0.05 vs posterior wall pacing).ConclusionPump function of the Atlantic cod heart ventricle is associated with activation‐to‐repolarization relationship: the longer repolarization at the site of activation origin provides the higher cardiac output.Support or Funding InformationThe study was supported by by the Ural Branch of the Russian Academy of Sciences (Project AAAA‐A18‐118012290365‐2) and the Program for Fundamental Research of RAS (AAAA‐A17‐117012310154‐6).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Swimming kinematics and temperature effects on spermatozoa from wild and captive shortnose sturgeon (Acipenser brevirostrum)

Computer-assisted semen analysis (CASA) and cluster analysis were used to compare spermatozoa swimming kinematics and milt quality between wild and captive shortnose sturgeon (Acipenser brevirostrum). Milt samples from 27 shortnose sturgeon were collected in May 2016 and June 2017. Of these, 19 were wild caught in the Saint John River, New Brunswick, Canada, and eight were from a captive population at the Mactaquac Biodiversity facility. The following kinematic variables were measured immediately following sperm activation (˜5 s), at 30, 60, and 180 s post-activation; average path velocity (VAP); straight-line velocity (VSL); curvilinear velocity (VCL); amplitude of lateral head displacement (ALH); beat cross frequency (BCF); straightness (STR); linearity (LIN); wobble (WOB); percent motility (MOT). Analyses were conducted at 7, 10, and 14 °C to determine potential effects of temperature on kinematics. Principal components analysis (PCA) of original kinematic variables yielded two main components, a speed/wobble component along with a movement pattern component. Hierarchical cluster analysis (HCPC) indicated there were distinct subpopulations, with composition of clusters the result of fish source (wild-caught or captive). Wild-caught fish had greater sperm densities (P = 0.0064) and sperm swimming speeds compared to captive fish (P < 0.05). Temperature had a significant effect only on captive spermatozoa, and this result was not consistent between time periods. There was no effect of hormonal manipulation on spermatozoa motility kinematics. Results indicate there are significant differences in measures of milt quality between wild and captive shortnose sturgeon, indicating an effect of rearing condition on reproductive potential, which may affect fertilization success.

The Effect of Difference Temperature on Cortisol, Glucose and Glycogen level of Uceng Fish (Nemacheilus fasciatus)

Nemacheilus is one of the genera of freshwater fish. The existence of Uceng fish ( Nemacheilus fasciatus ) in public waters is increasingly rare. Changes in water temperature in the maintenance medium will affect the physiological processes of fish. The purpose of this study was to analyze physiological responses (blood glucose levels, cortisol, and glycogen hormones) of Ucen g Fish ( N. fasciatus ) which were incubated at different temperatures and find out the initial time of Uceng fish adaptation to its new environment. Total of 200 fish were collected from wild catches in the Lekso River, Blitar. Fish tissue collection was carried out to test the profile of glucose, cortisol, and glycogen. The research activities at this stage were carried out by raising the Uceng fish from nature to a cultivation container in an aquarium of size 50 x 30 x 30 cm that given the different temperatures (20°C, 24°C, 28°C and 32°C), and each aquarium is filled with 10 Uceng fish and will be kept for 14 days. ELISA method was used to quantify the parameter. The result of this study showed highest peak of cortisol levels and blood glucose levels was achieved in the treatment of 24°C on the 10 th day and the lowest in the treatment temperature of 28°C on the 6 th day. The highest glycogen peak was reached at 32°C on day 10 and the lowest peak was reached at 28°C on day 2. We conclude that temperature affects the physiological response (cortisol, blood glucose, and glycogen) of Uceng fish ( N. fasciatus ). High levels of cortisol and blood glucose indicate stressful fish. Keywords: Fish, Nemacheilus fasciatus, Physiological, Temperature, Uceng.

Wild caught ornamental fish: a perspective from the UK ornamental aquatic industry on the sustainability of aquatic organisms and livelihoods.

The ornamental aquatic industry involves the global commercial trade of live aquatic organisms such as fish, invertebrates and plants. It comprises a range of businesses including collectors, breeders, exporters, importers and retailers. Together, these form a supply chain through which aquatic organisms pass from their point of origin to the end point e.g., domestic aquaria and ponds. On a worldwide basis, the legal and legitimate ornamental aquatic trade is subject to regulation and monitoring throughout the majority of its supply chain. Approximately 90% of ornamental freshwater fish species traded are captive-bred, but, due to their complex breeding cycles, 90-95% of ornamental marine fish species are wild-caught. The ornamental aquatic industry and consumers therefore have a responsibility to ensure that wild-caught species are sourced sustainably, legally and to good welfare standards. Such good practice should be considered a necessity for the longevity, not only of the ornamental aquatic industry, but of the livelihoods which depend on it and the future of ecosystems dependent on such communities.

Abnormal mortality of triploid adult Pacific oysters: Is there a correlation with high gametogenesis in Normandy, France?

Summer mortalities of the adult Pacific oysters Crassostrea gigas are an important economic concern. In 2015 and 2016, the mortality of hatchery origin spat comprising 4 diploid batches and 9 triploid batches as well as 12 batches of wild caught diploids was followed at 3 sites in Normandy. Abnormal mortalities (>20%) were observed at one site only and were significantly higher in triploid animals (P < .05). Triploid oysters are believed to be partially sterile but a high level of gametogenesis was observed in all monitored triploid batches. In 2015, preliminary results revealed that triploid oysters underwent strong gametogenesis with mature gametes (stage 3) and 50% of them were non-perturbed (i.e. named alpha). In 2016, 42% of triploid oysters were alpha. This study revealed that triploid oyster maturation occurred in September, which corresponded to the time of high mortalities in Normandy.

Analysis of immunoglobulin and T cell receptor gene expression in ballan wrasse (Labrus bergylta) revealed an extraordinarily high IgM expression in the gut

The serum IgM concentration of ballan wrasse is relatively high, estimated to approximately 13 mg/ml in adult wild fish of 800 g. The present study revealed an unusual high abundance of IgM mRNA in the gut of ballan wrasse. Initially, transcripts encoding IgM, IgT, IgD, TCRα, TCRδ and CD3ε were quantified by RT-qPCR in several tissues of wild caught fish (approx. 800 g), indicating an elevated immune activity in hindgut and an extraordinarily high expression of IgM. Subsequently, a new RT-qPCR analysis was performed on the entire intestine, cut into four different segments, of reared fish (32–100 g). The analysis indicated immune activity along the entire intestine, but not as strong as in the hindgut. Furthermore, similar to the larger fish, the relative abundance of IgM transcripts was higher in the hindgut than in kidney and spleen, although the absolute level of IgM was in general higher in the larger fish. The secreted form of IgM was completely dominant in comparison to the membrane bound form of IgM and the other analysed genes. IgM was purified from gut mucus and external mucosal surfaces by magnetic beads coated with protein A. Mucus IgM reacted with rabbit antisera raised against serum IgM and contained subunits of the same size. Regarding the elevated immune activity in the intestine it is tempting to speculate on a possible compensatory strategy in this lineage of stomach-less fish, and that natural antibodies have an important role in the first line defence.

Development of ovarian maturations in orange mud crab, Scylla olivacea (Herbst, 1796) through induction of eyestalk ablation and methyl farnesoate

Many crustacean species including mud crab, genus Scylla are incapable of natural maturation under captivity, thus putting high pressure on the wild catch. Therefore, to increase the availability of mature broodstocks in captivity, this study determined the effect of Eyestalk Ablation (EA) and Methyl Farnesoate (MF) administration on ovarian maturation stages of the orange mud crab, Scylla olivacea. The study was conducted using a control group (T1) consisting of 95% alcohol (widely used as a chemical solvent), and three treatment groups consisting of: 5 µl/g oral administrated MF in the diet (T2), EA (T3) and a combination of both treatments of MF and EA (T4). The highest percentage of ovarian maturation Stage 4 was found in the T4 treatment (20.8%) compared to the other treatments which were T1 (0%), T2 (8.33%) and T3 (12.5%). Ovarian development of the treated groups (T2, T3, and T4) was significantly different compared to the control group (T1) (p < 0.05). However, there was no significant difference observed in the mean Gonadosomatic Index (GSI) in orally administrated MF (T2) compared to the EA group (T3) (p > 0.05), but it was significantly different when compared to the combination group of MF and EA (T4) (p < 0.05). It can be concluded that the combination method of oral administration of MF through diet and EA (T4) is the best technique for producing mature ovaries.

Good, bad or ugly: all a matter of perspective?

Seafood Industry Australia (SIA) is the national peak body that represents the Australian seafood industry as a whole, including members from wild catch, aquaculture and post-harvest sectors. According to the Australian Institute of Marine Science (AIMS), the fishing and petroleum industries represent a combined contribution to the Australian economy of ~AU$28.5 billion (in 2015–2016) and employ (directly and indirectly) over 55000 Australians.1 At times, our industries’ interests have competed. However, we recognise that we can unlock value for the economy, and those who work in our industries, by finding effective ways to work together. In 2014, a Memorandum of Understanding (MOU) was signed between five commercial fishing and seafood industry associations and APPEA. This MOU committed to the core principles of improved cooperation, open communication and stronger consultation. There is significant benefit for both industries in learning how to improve shared access to marine resources, whether at the early stages of petroleum activities (e.g. seismic) or at the end of an asset’s life (e.g. decommissioning). This presentation will look at efforts to improve relationships between our two industries and make observations about potential ways forward.