Canthidermis Research Articles

Screening on halal gelatin extraction from spotted oceanic triggerfish (Chanthidermis maculata) skin using response surface methodology

Spotted oceanic triggerfish fish is one type of fish that has the potential to be a source of halal gelatin. Almost all parts of his body can become gelatin. In the process of processing the fish, many parts are wasted such as skin. Though this skin can be used for gelatin extract. From the results of the study, gelatin yield ranged from 2.7 – 9.3% with an average value of 5.50%. This gelatin has a viscosity value ranging from 6.21 – 7.57 cP which was analyzed using the Rapid Visco Analyzer (RVA) instrument and gel strength analysis using a Texture Analyzer and found results of 80.33 – 97.67 g / cm2. Based on the probability value < 0.05 yield, viscosity, and gel strength of gelatin, it is known that there are several independent variables that have a real effect on yield, namely variables B (concentration of H2SO4), D (soaking duration), F (ratio of water/extraction skin) and G (extraction temperature). In viscosity, the influential variables are C (citric acid concentration), D (soaking duration), E (soaking water/skin ratio) and G (extraction temperature). While on gel strength, the influential variables are A (NaOH concentration) and G (extraction temperature). The influence of factors on response can be sorted sequentially, namely the order in yield is G>F>B>D>A>H>C>E, in viscosity is C>E>D>G>H>A>B>F and in gel strength is G>A>E>H>B>F>C>D. This indicates that the G factor (extraction temperature) was selected as the most important factor, and the 2nd and 3rd most important factors can be selected from A (NaOH concentration), B (H 2SO4 concentration), D (extraction duration) and E (soaking water/skin ratio), and H (extraction duration).

Risk assessment and study of trace/heavy metals in three species of fish of commercial interest on the island of El Hierro (Canary Islands, eastern-central Atlantic)

The levels of toxic heavy metals (Al, Cd, Pb), macroelements (Ca, K, Mg, Na) and microelements and trace elements (B, Ba, Co, Cr, Cu, Fe, Li, Mn, Mo, Ni, Sr, V, Zn) were determined in 54 muscle samples from three species of fish for human consumption, Balistes capriscus (grey triggerfish), Canthidermis sufflamen (oceanic triggerfish) and Heteropriacanthus fulgens (rock catalufa), using spectrometry of inductively coupled plasma optical emission (ICP-OES). The aims of this study is to determine if the three species are good bioindicators of environmental pollution and to verify whether they are suitable for human consumption. Significant differences were found in the levels of Al, B, Fe, K, Mn, Mo, Na and Zn between the three species studied. The results suggest that the underwater volcano off El Hierro influences the metallic content (Al, K the most characteristic) of H. fulgens. An evaluation of the toxic risk derived from the ingestion of B. capriscus, C. sufflamen and H. fulgens was carried out, analyzing the Admissible Daily Intake (ADI) and the Safety Margin (MoS). For the nutritional study, the Recommended Daily Intake (RDI) index was used. Therefore, once the study has been carried out and under the conditions established in terms of daily / weekly fish consumption, proposed by AESAN, there would not be any type of toxic risk after ingesting B. capriscus, C. sufflamen and H. cruentatus.

Predicting bycatch hotspots in tropical tuna purse seine fisheries at the basin scale

Fisheries observer programs represent the most reliable way to collect data on fisheries bycatch. However, their limited coverage leads to important data gaps that preclude bycatch mitigation at the basin scale. Habitat models developed from available fisheries observer programs offer a potential solution to fill these gaps. We focus on tropical tuna purse seine fisheries (TTPSF) that span across the tropics and extensively rely on floating objects (FOBs) for catching tuna schools, leading to the bycatch of other species associated with these objects. Bycatch under floating objects is dominated by five species, including the vulnerable silky shark Carcharhinus falciformis and four bony fishes (oceanic triggerfish Canthidermis maculata, rainbow runner Elagatis bipinnulata, wahoo Acanthocybium solandri, and dolphinfish Coryphaena hippurus). Our objective was to predict possible bycatch hotspots associated with FOBs for these five species across two tropical oceans. We used bycatch data collected from observer programs onboard purse seiners in the Atlantic and Indian oceans. We developed a generalized additive model per species and per ocean relating bycatch to a set of environmental covariates (depth, chlorophyll-a concentration, sea surface temperature, mixed layer depth, surface salinity, total kinetic energy and the density of floating objects) and temporal covariates (year and month). We extrapolated modeled relationships across each ocean within the range of environmental covariates associated with the bycatch data and derived quarterly predictions. We then detected bycatch hotspots as the 90th percentiles of predictions. In the Atlantic Ocean, bycatch hotspots were predicted throughout tropical and subtropical waters with little overlap between species. By contrast in the Indian Ocean, major overlapping hotspots were predicted in the Arabian Sea throughout most of the year for four species, including the silky shark. Our modeling approach provides a new analytical way to fill data gaps in fisheries bycatch. Even with the lack of evaluation inherent to extrapolations, our modeling effort represents the first step to assist bycatch mitigation in TTPSF and is applicable beyond these fisheries.

Drifting along in the open-ocean: The associative behaviour of oceanic triggerfish and rainbow runner with floating objects

Multispecies aggregations at floating objects are a common feature throughout the world's tropical and subtropical oceans. The evolutionary benefits driving this associative behaviour of pelagic fish remains unclear and information on the associative behaviour of non-tuna species remains scarce. This study investigated the associative behaviour of oceanic triggerfish (Canthidermis maculata) and rainbow runner (Elagatis bipinnulata), two major bycatch species in the tropical tuna purse seine fishery, at floating objects in the western Indian Ocean. A total of 24 rainbow runner and 46 oceanic triggerfish were tagged with acoustic transmitters at nine drifting FADs equipped with satellite linked receivers. Both species remained associated with the same floating object for extended periods; Kaplan-Meier survival estimates (considering the censored residence time due to equipment failure and fishing) suggested that mean residence time by rainbow runner and oceanic triggerfish was of 94 and 65 days, respectively. During daytime, the two species increased their home range as they typically performed short excursions (<2 h) away from the floating objects. Rainbow runner performed more excursions per unit time than oceanic triggerfish; the mean excursion index was 0.86 (±0.8 SD) for oceanic triggerfish and 1.31 (±1.1 SD) for rainbow runner. Ambient light intensity appears to be the stimulus triggering the onset and end of the associative modes. The observed prolonged residency of these two major bycatch species suggests that they are more vulnerable to the tropical tuna purse seine gear than the targeted tuna species.

Association dynamics of tuna and purse seine bycatch species with drifting fish aggregating devices (FADs) in the tropical eastern Atlantic Ocean

Several pelagic fish species are known to regularly associate with floating objects in the open ocean, including commercially valuable species. The tuna purse seine industry takes advantage of this associative behavior and has been increasingly deploying free-drifting man-made floating objects, also known as fish aggregating devices (FADs). Using passive acoustic telemetry, this study describes the associative dynamics of the main targeted tropical tuna species (Thunnus albacares, T. obesus and Katsuwonus pelamis), as well as three major bycatch species, silky shark (Carcharhinus falciformis), rainbow runner (Elagatis bipinnulata) and oceanic triggerfish (Canthidermis maculata). Short-term excursions away from the FADs were frequently performed by all tuna species as well by silky sharks. These excursions were characterized by a marked diel pattern, mainly occurring during nighttime. Rainbow runners and oceanic triggerfish were much more present at the FADs and rarely performed excursions. Average continuous residence times (CRTs) ranged from 6 days, for silky shark, up to 25 days for bigeye tuna. Similar to silky shark, average CRTs for skipjack tuna and oceanic triggerfish were less than 10 days. For yellowfin tuna and rainbow runner, CRTs averaged 19 and 16 days, respectively. Bigeye and yellowfin tuna remained associated to a single drifting FAD for a record of 55 days and 607 km traveled.

Preparation and characterization of biodegradable film based on skin and bone fish gelatin

Biodegradable films can act as excellent oxygen, water, and lipid barrier. Gelatin is utilized extensively as a gelling agent, emulsifier, stabilizer, adhesives, viscosity agent, binder agent and film-forming agent. Fish gelatin as a film-forming agent has unique characteristics but varies depending on fish species. The study aims to characterize biodegradable film made using skin and bone fish gelatin with the addition of plasticizer. Gelatin of ocean fish, spotted oceanic triggerfish (Canthidermis maculata), and freshwater fish, tilapia (Oreochromis niloticus) were used. As a plasticizer, glycerol or sorbitol with concentrations of 0.25 and 0.5 % was added. Gelatin of spotted oceanic triggerfish resulted in film with higher tensile strength, whereas tilapia gelatin with glycerol produced biodegradable film with higher elongation and water vapor permeability. The best characteristics of biodegradable film made from gelatin of spotted oceanic triggerfish with 0.25% sorbitol.

Extraction and Properties of Gelatin from Spotted Oceanic Triggerfish (Canthidermis maculata) Skin and Bone

Effects of pretreatments with different alkali and acid concentrations, and extraction temperatures on fish gelatin extraction and properties was studied. The resultant fish gelatins were evaluated in terms of extraction yield, viscosity, gel strength, and pH. The combination of higher acid pretreatment concentrations and extraction temperatures removed the noncollagenous protein and provided proper pH extraction condition which resulted higher gelatin extraction yield. However, the gel strength decreased with the increase of acid concentration. The gel strength and pH of gelatin increase proportionally to the increase in alkali concentration and extraction temperature. No significant effects of the three treatments on the gelatin viscocity. The recommended gelatin extraction process conditions was using alkali concentration (NaOH) of 0.55 N, acid (HCl) of 0.95 N, and a temperature of 60 °C. The optimal solution formula had optimization targets of 79.5% and was predicted to produce a gel with 11.21% yield and pH 3.4

Behaviour and vulnerability of target and non-target species at drifting fish aggregating devices (FADs) in the tropical tuna purse seine fishery determined by acoustic telemetry

Characterizing the vulnerability of both target and non-target (bycatch) species to a fishing gear is a key step towards an ecosystem-based fisheries management approach. This study addresses this issue for the tropical tuna purse seine fishery that uses fish aggregating devices (FADs). We used passive acoustic telemetry to characterize, on a 24 h scale, the associative patterns and the vertical distribution of skipjack (Katsuwonus pelamis), yellowfin (Thunnus albacares), and bigeye tuna (Thunnus obesus) (target species), as well as silky shark (Carcharhinus falciformis), oceanic triggerfish (Canthidermis maculata), and rainbow runner (Elagatis bipinnulata) (major non-target species). Distinct diel associative patterns were observed; the tunas and the silky sharks were more closely associated with FADs during daytime, while the rainbow runner and the oceanic triggerfish were more closely associated during the night. Minor changes in bycatch to catch ratio of rainbow runner and oceanic triggerfish could possibly be achieved by fishing at FADs after sunrise. However, as silky sharks display a similar associative pattern as tunas, no specific change in fishing time could mitigate the vulnerability of this more sensitive species. For the vertical distribution, there was no particular time of the day when any species occurred beyond the depth of a typical purse seine net. While this study does not provide an immediate solution to reduce the bycatch to catch ratios of the FAD-based fishery in the western Indian Ocean, the method described here could be applied to other regions where similar fisheries exist so as to evaluate potential solutions to reducing fishing mortality of non-target species.

The Potency Of Chanthidermismaculates Fish For Surimi Production

The aim of this study was to explore the potency of Chanthidermis maculates fish (spotted oceanic triggerfish) for surimi production. The effect of washing frequency (one or two washing cycle) and sucrose concentration (0, 2, 4, and 6%) as cryoprotectant on the quality of the surimi was investigated. The analyzed parameters in the study consisted of yield, moisture, protein, ash and fat contents, pH value, folding and sensory evaluation test (color and texture). The results showed that the best treatment in this study based on the protein content, folding and sensory test was obtained from the combination of treatment with no addition of sucrose and one washing cycle. That treatment resulted surimi with the yield of 80.62%, moisture, protein, ash, and fat contents of 71.47%, 20,88%, 0.61%, and 2.34%, respectively, and pH of 6.37%, folding test of 3.00, and color sensory test of 5.12 (light cream), texture of 3.75 (elastic).

Satellite-linked acoustic receivers to observe behavior of fish in remote areas

Automated acoustic receivers are now widely used by biologists to study the behavior of fish. However, currently available acoustic receivers require physical recovery of the units to download stored data. Such operation is often difficult in remote study areas like in the open ocean. We present a new satellite-linked acoustic receiver (Vemco VR3-Argos) that allows downloading data through a satellite uplink (Argos). The VR3-Argos can last up to one year, sending GPS positions and tag data at regular time intervals. We illustrate the advantages of this new technology with tagging data from 121 fish of seven species (yellowfin tuna, bigeye tuna, skipjack tuna, wahoo, dolphinfish, silky shark and oceanic triggerfish) caught and released around drifting fish aggregating devices (FADs) in the Western Indian Ocean, far from any land. In opposition with the classic acoustic receivers (Vemco VR2), the use of VR3-Argos allowed to collect data for several weeks after leaving the drifting FADs. Maximum residence times of 3 days for bigeye tuna, 7 days for skipjack, 8 days for wahoo, 10 days for silky shark and 15 days for yellowfin tuna, dolphinfish and oceanic triggerfish could be recorded. VR2 and VR3-Argos are equivalent in terms of quality of residence times data, however depth data obtained through satellites are aggregated in 8 classes for compression purposes, which leads to a loss of precision available with raw data. Future directions of this technology are discussed.

Characterizing fish communities associated with drifting fish aggregating devices (FADs) in the Western Indian Ocean using underwater visual surveys

We adapted a visual census method, mainly used in demersal and reef fish studies, to characterize fish communities associated to drifting fish aggregating devices (FADs) in the Western Indian Ocean. Drifting FAD associ- ated fishes from both equatorial (Seychelles) and tropical waters (Reunion Island) were examined by divers. A total of 32 species (belonging to 16 families) were observed associated with drifting FADs in equatorial waters, and 24 species (14 families) were found around FADs in tropical waters. Twenty species were found in both regions. The highest number of species observed at a single FAD was 18 (12 ± 2, mean ± SD) in equatorial and 13 (10 ± 3) in tropical waters, not counting circumnatant species loosely associated with the FAD. Some species like Kyphosus vaigiensis, Canthidermis maculata, Elagatis bipinnulata, Acanthocybium solandri and Coryphaena hippurus were observed on all or most of the surveys. In this study, the contribution in biomass of the 18 common species associated with drifting FADs (but excluding circumnatant species), represents more than 98% of the biomass. The overall biomass values of closely associated species remains well below tuna biomass estimates for circumnatant tuna schools at FADs, estimated as high as 200 tons. The species that most significantly contribute to the by-catch in tuna purse-seines logically match those that showing the highest biomass values in our surveys (Carcharhinus spp., Elagatis bipinnulata, Coryphaena hippurus, Canthidermis maculata ,a ndAcanthocybium solandri). One of the most abundant and ubiquitous species in our study was the spotted oceanic triggerfish Canthidermis maculata that sometimes formed massive schools of many thousands individuals around the drifting FADs. Future research is needed to explore the role of such non tuna species in the attraction and aggregation processes of tuna around drifting FADs.