This paper presents the technological developments and the policy contexts for the project "Autonomous Robotic Sea-Floor Infrastructure for Bentho-Pelagic Monitoring" (ARIM). The development is based on the national experience with robotic component technologies that are combined and merged into a new product for autonomous and integrated ecological deep-sea monitoring. Traditional monitoring is often vessel-based and thus resource demanding. It is economically unviable to fulfill the current policy for ecosystem monitoring with traditional approaches. Thus, this project developed platforms for bentho-pelagic monitoring using an arrangement of crawler and stationary platforms at the Lofoten-Vesterålen (LoVe) observatory network (Norway). Visual and acoustic imaging along with standard oceanographic sensors have been combined to support advanced and continuous spatial-temporal monitoring near cold water coral mounds. Just as important is the automatic processing techniques under development that have been implemented to allow species (or categories of species) quantification (i.e., tracking and classification). At the same time, real-time outboard processed three-dimensional (3D) laser scanning has been implemented to increase mission autonomy capability, delivering quantifiable information on habitat features (i.e., for seascape approaches). The first version of platform autonomy has already been tested under controlled conditions with a tethered crawler exploring the vicinity of a cabled stationary instrumented garage. Our vision is that elimination of the tether in combination with inductive battery recharge trough fuel cell technology will facilitate self-sustained long-term autonomous operations over large areas, serving not only the needs of science, but also sub-sea industries like subsea oil and gas, and mining.

2019 IMEKO TC-19 International Workshop on Metrology for the Sea (MetroSea 2019), 3-5 October 2019, Genova, Italy.-- 6 pages, 6 figures

Inducing unconsciousness in fish using electrical stunning prior to slaughter may improve fish welfare and fillet quality if such practises can be disseminated into wild capture fisheries. The objectives of this study were to: 1) evaluate if an established slaughter protocol consisting of dry electrical stunning (using a coupled AC/DC current at ≈ 110 Vrms) followed by chilling could be used to stun the wild captured species Atlantic mackerel (Scomber scombrus) unconscious within 0.5 s; 2) determine if death could be induced without consciousness recovery by longer duration stunning (5 s) combined with chilling in an ice/water slurry for 6 min; and 3) examine the extent of quality defects arising from the applied slaughter protocol. We determined consciousness by examination of behavioural responses in a standardised vitality assessment. Out of a sample of 10 mackerel, 9 were assumed to be rendered unconscious by the 0.5 s stun, as determined by the presence of tonic and/or clonic muscle cramping consistent with a general epileptic insult. Assumed unconsciousness was maintained throughout chilling treatment in all fish (n = 25) following a full stun of 5 s. All fish were assumed to have died as a result of the protocol. There was no evidence of spinal damage or haematoma quality defects post filleting. These results suggest that the examined protocol is effective at slaughtering mackerel in a manner consistent with good welfare and without inducing quality defects, but further research is required to verify the unconscious condition via electroencephalogram (EEG) and before the procedure can be applied in wild capture fisheries.

In the face of climate change and increasing use of coastal areas, there is a need for high temporal resolution data provided in near real-time, serving research, management, and commercial users. The main objective of Lofoten-Vesterålen (LoVe) Cabled Ocean Observatory is to significantly contribute to the knowledge base of the physical, chemical, and biological environment of the ecologically and economically important LoVe shelf-slope-system. Key sensors for this task are based on acoustical methods for biological and physical oceanography. The majority of the observatory nodes are equipped with state-of-the art scientific echosounders, hydrophones, and acoustic Doppler current profilers (ADCP). Echosounders monitor vertical distribution and density of marine organisms (fish, zooplankton) and biomass flux across the observatory transect. Hydrophones provide continuous monitoring of anthropogenic noise and detection (absence/presence) of vocalizing marine mammals and fish. In addition to the fiber optic communication along the infrastructure subsea cables, each node has the capability of acoustic communication to non-cabled nodes, vessels, and vehicles. The instrument nodes and satellites on which the sensors are mounted feature a range of novel solutions, including technologies contributing to significant reduction in the cost of maintaining the infrastructure compared to traditional cabled infrastructure technologies.

Wild haddock (Melanogrammus aeglefinus) of commercial size (0.8–2.49kg, 45–60cm) were swum to exhaustion in a large swim tunnel and then allowed to recuperate for 0, 3 or 6h, to investigate the effects of exhaustive swimming on blood glucose, blood lactate and post mortem development of fillet quality. There was a positive linear relationship between critical (aerobic) swimming speed (Ucrit) and body length (BL). The average Ucrit was 1.25±0.29 (SD) BL s−1, which is close to that reported by others for haddock. Swimming to exhaustion resulted in reduced time to reach maximum muscle stiffness of the fillet (no recuperation vs unswum control), but the effect was remedied by recuperation for 3h or more. Blood glucose and blood lactate increased during exercise and remained elevated throughout the entire 6-h resting period, indicating that complete recovery of these parameters may take more than 6h. There was no significant effect of exhaustive swimming on muscle pH or colouration of the fillet. Taken together, the data suggest that swimming to exhaustion may have moderate and reversible negative effects on fillet quality in haddock. The effects observed in the present study are consistent with a recent study on exhaustive swimming in Atlantic cod, but less severe than that reported for haddock caught by trawl. This suggests that other factors (e.g. crowding/packing in the codend, barotrauma or suffocation) are contributing to the deterioration of fillet quality seen frequently in haddock caught by trawl.

To determine the optimal electrical stunning conditions for edible crabs ( Cancer pagurus ) their impedance was investigated along with currents with the potential to render the animal insensible within 1 s. This information was used to develop a commercial stunner and determine conditions that both stun and kill the animals instantaneously. Results show that the crabs’ impedance is dependent on the current frequency with the optimum outcome seen at net frequencies of 50–60 Hz. The proportion of animals stunned was dependent on the potential difference with 220 V required to stun an animal unconscious within 1 s. Any attempts to kill the crab with asphyxia after a 10-s exposure to electricity failed as 30% of crabs recovered within an hour. A thermal shock, pre- or post-stunning prevented this recovery. Autotomy was not avoided and approximately 4–7% of crabs lost one or more appendage. Electricity caused localised over-heating, but a current of 10-s duration did not cause heating of the carapace. We conclude that electrical stunning used in combination with a thermal shock may stun and kill the animal instantaneously.

The objective of this study was to verify the optimal AC frequency range to be used during industrial electrostunning, i.e. electro-narcosis, of Atlantic salmon (Salmo salar) by investigating the electrical impedance spectra of the combined fish and electro-stunning device entity. The electrical impedance and appurtenant phase shiftwasmeasured in the frequency range 40 Hz to 1.0 MHz for individual fish (n=11) placed in a regular electrical stunner. The results of the experiment show that the average overall impedance of the combined fish and electrical stunning device increases with frequency from 40 to 60 Hz before leveling out in the range from 60 to 800 Hz. Thereafter the impedance decreases to a negligible value at 1 MHz. Measurements on impedance and phase angle show that the highest average electrical impedance is at 100 Hz. Furthermore, there are individual peak impedance variations between 70 and 100 Hz. In all fish measured, the impedance at 900 Hz was observed to be lower than that at adjacent frequencies. Due to the measured average impedance values, and the expected influence of the alpha dispersions on the cell surface as reported in previous research, it is concluded that the optimal AC frequency range for electro-stunning of the Atlantic salmon brain is 70 to 100 Hz. (C) 2015 Published by Elsevier B.V.

To understand the importance of electrical frequencies on stunning, recovery and inflicting injuries, Atlantic salmon (Salmo salar) were exposed for 5s to either 217V, 50Hz, AC or 107V coupled AC+DC at 200Hz, containing a high frequency spectrum or not. Post stun the fish were placed back into water, either at ambient seawater temperature (10.4°C) or cold water (−1.3°C), to look upon recovery or mortality. Results show that a high frequency spectrum at low decibels prevents the muscles from contracting in such a degree that spinal injuries and haemorrhaging were prevented in all individuals. Injury rates of 14 and 18% were observed when using electrical signals containing only low frequencies of 200Hz AC+DC and 50Hz, AC. The high frequency spectrum also reduced the stimulation of the brain as fish recovered faster with no mortality. Adding a cold shock post stunning delayed or prevented recovery of all groups within the time span required to kill the fish by exsanguination.

An optimum setting for electrical stunning of Atlantic salmon under commercial conditions was tested and compared against percussive stunning before and after pumping and at increasing durations of crowding (0.5 and 3h). For electrical stunning the fish were exposed to 60V, 100HzAC+DC for 6s after pumping. The results show that there were no significant differences in muscle pH or rigor index between fish exposed to electricity or a percussive force. Pumping and crowding did have a significant effect. Pumping alone halved the time until maximum rigor from 24 to 12h post mortem. Increasing crowding for 3h caused a significant drop in muscle pH and the time until onset of maximum rigor tension was reduced to 6h post mortem. We conclude that optimum electrical stunning performs equally well as percussive stunning and that future challenges for improving the pre rigor times for Atlantic salmon lays in the pumping and crowding conditions, and not in the selected stunning technique.

Investigation of the physiological effects of live chilling in Atlantic salmon, Salmo salar, has been performed in two experiments. In the first, fish (mean weight 840 g) acclimatized to either 16, 8, or 4°C were directly transferred horizontally or vertically (9 combinations) to water temperatures of 16, 8, 4, or 0°C using a dip net. Blood samples were collected at 1 and 6 h (h) post-transfer. In the second experiment, fish (mean weight 916 g) acclimatized to 16°C were exposed to four temperature-drop regimes (no physical handling): 16–4°C (over 5 h), 16–4°C (over 1 h), 16–0°C (over 5 h), and 16–0°C (over 1 h). Blood samples were collected 1 h post-temperature drop. Physical transfers in the first trial, i.e., temperature drops, resulted in immediate (1 h) increases in blood lactate concentrations at all three temperatures, but levels were significantly reduced and close to pre-transfer levels after 6 h. Horizontal transfers, i.e., 16–16°C, 8–8°C, and 4–4°C, resulted in similar increases and were not significantly different from the groups exposed to temperature drops. The most severe vertical transfer (16-0) resulted in a swift loss of equilibrium and eventually death. In experiment 2, temperature drops from 16 to 4°C and from 16 to 0°C over a period of one or 5 h, without physically handling the fish, resulted in no significant increases in any of the measured parameters 1 h post-transfer, except in the 16–0 (1 h) group. The latter experienced a significant increase in blood sodium, glucose, lactate, and cortisol levels compared to all other groups. The results suggest that salmon are capable of tolerating relatively steep temperature drops without any significant negative effects on blood stress parameters and that physical stress from handling overrides the effect of thermal insults.

The overall objective of the study was to evaluate a percussive and an electrical stunning method under laboratory conditions in Atlantic salmon. Evidence of unconsciousness and insensibility of the salmon was provided on the electroencephalogram (EEG) by the appearance of slow waves and spikes, followed by a strong depression in electrical activity. This phenomenon was observed in 17 salmon after percussive stunning using an air pressure of 8.1 to 10 bars, whilst 8 fish were considered conscious at pressures below 8.1 bars although some were seemingly unconscious on behaviour. Consequences were a haemorrhage in the brain cavity in 15 out of 17 fish, broken upper or lower jaws in 9 fish and eye burst in 8 fish. A general epileptiform insult (unconscious and insensible) was obtained by delivering a voltage, consisting of a direct current (DC) coupled with 100 Hz alternating current (AC) with a peak value of approximate to 112 volt (V), head to body, for approximate to 0.5 s. The total duration of the insult was 62 +/- 44 s (mean +/- SD; n = 25) which was followed by minimal brain activity in 19 fish. The heart rate was 20 +/- 7 beats/min prior to stunning. After stunning the electrocardiogram (ECG) revealed fibrillation for 22 15 s and became irregular and showed extra systolae (ventrical contraction) afterwards.Exposing the salmon for 5 s with electricity followed by a gill cut resulted that 1 out of 3 fish recovered temporary after 3 min. Haemorrhages were not observed in the fillets. Average current for head to body electrical dry stunning was 668 milliampere (mA) root mean square (RMS) with an average stunning voltage of 107.9 V-rms. Electrical head to body stunning can be recommended when using coupled AC and DC current of 668 mA(rms) and approximate to 107 V-rms. The salmon can be stunned in approximate to 0.5 s. However, a correct bleeding procedure should be developed.For percussive stunning we conclude that if sufficient force is used the fish will be rendered unconscious insensible which result in damage of the carcass, whereas a combined AC and DC can be recommended source for dry electrical head to body stunning. (C) 2009 Elsevier B.V. All rights reserved.