Reflex impairment, physiological stress, and discard mortality of European plaice Pleuronectes platessa in an otter trawl fishery

2017 ◽  
Vol 74 (6) ◽  
pp. 1660-1671 ◽  
Author(s):  
Caroline Methling ◽  
Peter V. Skov ◽  
Niels Madsen
Keyword(s):  
Physiological Stress ◽  
Plasma Osmolality ◽  
Control Fish ◽  
Otter Trawl ◽  
Air Exposure ◽  
Trawl Fishery ◽  
Physiological Variables ◽  
Discard Mortality ◽  
Fisheries Policy ◽  
Short Term Mortality

Abstract The reformed European Common Fisheries Policy introduced a discard ban, with a possibility of exempting species where a high discard survival can be demonstrated. This necessitates a validation of the methods used for estimating the discard mortality of candidate species. In this study, we assess whether reflex impairment can predict short-term mortality in commercially trawled European plaice upon landing and after air exposure of up to 90 min. Sub-lethal stress was assessed by a suite of physiological variables. Over a 10-day period, mortality was monitored for a total of 199 plaice following trawl and air exposure of varying duration, and for 50 control fish scored for reflex impairment on board the vessel. Mortality was only observed in fish exposed to air for >60 min, and averaged 11.1% (95% CI = 7.1–16.3%). Reflex impairment was found to be a significant (P < 0.001) predictor of mortality in a generalized linear model, excluding other initially included variables by using a stepwise method. Plasma cortisol, haematocrit, and plasma osmolality all indicated a profound and increasing level of stress with air exposure, accompanied by a near depletion of muscle phosphocreatine and nucleotides. Fishing site had an unexpected, but significant (p < 0.05) effect on stress levels, which was also reflected in reflex impairment and mortality. Based on these findings, a possible exemption from the discard ban should include considerations on the duration of air exposure.

scholarly journals Injury, reflex impairment, and survival of beam-trawled flatfish

2016 ◽  
Vol 73 (4) ◽  
pp. 1244-1254 ◽  
Author(s):  
Sebastian S. Uhlmann ◽  
Ruben Theunynck ◽  
Bart Ampe ◽  
Marieke Desender ◽  
Maarten Soetaert ◽  
...  
Keyword(s):  
Seawater Temperature ◽  
Control Fish ◽  
Commercial Fishing ◽  
High Survival ◽  
Air Exposure ◽  
Trawl Fishery ◽  
Solea Solea ◽  
Impairment Score ◽  
In Captivity ◽  
Number Of Individuals

Abstract Under the “high survival” exemption of the European landing obligation or discard ban, monitoring vitality and survival of European flatfish becomes relevant to a discard-intensive beam trawl fishery. The reflex action mortality predictor (RAMP) method may be useful in this context. It involves scoring for the presence or absence of natural animal reflexes to generate an impairment score which is then correlated with post-release or discard mortality. In our first experiment, we determined suitable candidate reflexes for acclimated, laboratory-held European plaice (Pleuronectes platessa) and common sole (Solea solea). In a second experiment, we quantified reflex impairment of commercially trawled-and-handled plaice and sole in response to commercial fishing stressors. In a third experiment, we tested whether a combined reflex impairment and injury (vitality) score of plaice was correlated with delayed post-release mortality to establish RAMP. Five-hundred fourteen trawled-and-discarded plaice and 176 sole were assessed for experimentally confirmed reflexes such as righting, evasion, stabilise, and tail grab, among others. Of these fish, 316 plaice were monitored for at least 14 d in captivity, alongside 60 control plaice. All control fish survived, together with an average of 50% (±29 SD) plaice after being trawled from conventional, 60 min trawls and sorted on-board a coastal beam trawler. Stressors such as trawl duration, wave height, air, and seawater temperature were not as relevant as a vitality score and total length in predicting post-release survival probability. In the second experiment where survival was not assessed, reflex impairment of plaice became more frequent with prolonged air exposure. For sole, a researcher handling-and-reflex scoring bias rather than a fishing stressor may have confounded results. Scoring a larger number of individuals for injuries and reflexes from a representative selection of trawls and trips may allow for a fleet-scale discard survival estimate to facilitate implementation of the discard ban.

scholarly journals Use of avoidance behaviours to reduce the economic impacts of the EU Landing Obligation: the case study of a mixed trawl fishery

2019 ◽  
Vol 76 (6) ◽  
pp. 1554-1566
Author(s):  
Fabien Pointin ◽  
Fabienne Daurès ◽  
Marie-Joëlle Rochet
Keyword(s):  
Temporal Distribution ◽  
Grid Method ◽  
Fishing Effort ◽  
Economic Losses ◽  
Otter Trawl ◽  
Trawl Fishery ◽  
Nested Grid ◽  
Fishing Practices ◽  
The Eu

Abstract The EU Landing Obligation (LO) is designed to reduce bycatch (i.e. unwanted catch) through more selective fishing practices, such as avoidance behaviours which consist in allocating fishing effort to other species, fishing grounds or seasons. Incentives for fishers to change their behaviours depend on their economic performances as well as their ability to avoid bycatch. Changes in economic performances under the LO are evaluated based on cost and revenue equations. The nested grid method is then used to explore the spatial and temporal distribution of landings and discards, and to suggest alternative effort allocation to avoid bycatch. This article is focussed specifically on the French otter trawl fishery in the eastern English Channel and southern North Sea. Results suggest that under the LO the choke species problem will curtail fishing activities earlier in the year, leading to significant economic losses. In the absence of significant quota top-ups (at least 75%), a change in fishing practices consisting in reducing overall bycatch by 30% is insufficient to reduce losses. With a particular attention to choke species, more economically efficient avoidance strategies can be found thanks to the nested grid method.

scholarly journals Pre-Exercise Rehydration Attenuates Central Fatigability during 2-Min Maximum Voluntary Contraction in Hyperthermia

Medicina ◽  
2019 ◽  
Vol 55 (3) ◽  
pp. 66
Author(s):  
Kazys Vadopalas ◽  
Aivaras Ratkevičius ◽  
Albertas Skurvydas ◽  
Saulė Sipavičienė ◽  
Marius Brazaitis
Keyword(s):  
Body Weight ◽  
Physiological Stress ◽  
Maximum Voluntary Contraction ◽  
Thermal Strain ◽  
Plasma Osmolality ◽  
Voluntary Contraction ◽  
Whole Body ◽  
Knee Extensors ◽  
Lower Body ◽  
Whole Body Hyperthermia

Background and objectives: Hyperthermia with dehydration alters several brain structure volumes, mainly by changing plasma osmolality, thus strongly affecting neural functions (cognitive and motor). Here, we aimed to examine whether the prevention of significant dehydration caused by passively induced whole-body hyperthermia attenuates peripheral and/or central fatigability during a sustained 2-min isometric maximal voluntary contraction (MVC). Materials and Methods: Ten healthy and physically active adult men (21 ± 1 years of age) performed an isometric MVC of the knee extensors for 2 min (2-min MVC) under control (CON) conditions, after passive lower-body heating that induced severe whole-body hyperthermia (HT, Tre > 39 °C) with dehydration (HT-D) and after HT with rehydration (HT-RH). Results: In the HT-D trial, the subjects lost 0.94 ± 0.15 kg (1.33% ± 0.13%) of their body weight; in the HT-RH trial, their body weight increased by 0.1 ± 0.42 kg (0.1% ± 0.58%). After lower-body heating, the HT-RH trial (vs. HT-D trial) was accompanied by a significantly lower physiological stress index (6.77 ± 0.98 vs. 7.40 ± 1.46, respectively), heart rate (47.8 ± 9.8 vs. 60.8 ± 13.2 b min−1, respectively), and systolic blood pressure (−12.52 ± 5.1 vs. +2.3 ± 6.4, respectively). During 2-min MVC, hyperthermia (HT-D; HT-RH) resulted in greater central fatigability compared with the CON trial. The voluntary activation of exercising muscles was less depressed in the HT-RH trial compared with the HT-D trial. Over the exercise period, electrically (involuntary) induced torque decreased less in the HT-D trial than in the CON and HT-RH trials. Conclusions: Our results suggest that pre-exercise rehydration might have the immediate positive effect of reducing physiological thermal strain, thus attenuating central fatigability even when exercise is performed during severe (Tre > 39 °C) HT, induced by passive warming of the lower body.

State entrepreneurship in New South Wales’ trawl fishery, 1914-1923

2020 ◽  
Vol 32 (3) ◽  
pp. 636-655
Author(s):  
Lif Lund Jacobsen
Keyword(s):  
New South ◽  
New South Wales ◽  
Consumer Market ◽  
Fish Stocks ◽  
Trawl Fishery ◽  
South Wales ◽  
Policy Goals ◽  
Fisheries Policy ◽  
Economic Failure ◽  
New Consumer

In 1914, the New South Wales (NSW) Government decided to alter its fisheries policy, with the development of an offshore trawling industry supplanting support for inshore fishing as its key development objective. Accordingly, between 1915 and 1923 the NSW Government operated a commercial trawling industry designed to fish previously unexploited fish stocks on the state’s continental shelf. The State Trawling Industry (STI) was designed to meet a mix of social and economic policy goals, with the NSW Government controlling all parts of the production line from catching to selling produce. This article examines the business structure of the enterprise to reveal the reasons for its economic failure. It argues that government entrepreneurship created a new consumer market and unintentionally paved the way for the rise of a modern private trawling industry.

Vulnerability to predation and physiological stress responses in juvenile chinook salmon (Oncorhynchus tshawytscha) experimentally infected with Renibacterium salmoninarum

1998 ◽  
Vol 55 (7) ◽  
pp. 1599-1606 ◽  
Author(s):  
Matthew G Mesa ◽  
Thomas P Poe ◽  
Alec G Maule ◽  
Carl B Schreck
Keyword(s):  
Stress Responses ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Physiological Stress ◽  
Smallmouth Bass ◽  
Control Fish ◽  
Infection Level ◽  
Renibacterium Salmoninarum ◽  
Juvenile Chinook Salmon ◽  
Juvenile Chinook

We experimentally infected juvenile chinook salmon (Oncorhynchus tshawytscha) with Renibacterium salmoninarum (Rs), the causative agent of bacterial kidney disease (BKD), to examine the vulnerability to predation of fish with differing levels of Rs infection and assess physiological change during progression of the disease. Immersion challenges conducted during 1992 and 1994 produced fish with either a low to moderate (1992) or high (1994) infection level of Rs during the 14-week postchallenge rearing period. When equal numbers of treatment and unchallenged control fish were subjected to predation by either northern squawfish (Ptychocheilus oregonensis) or smallmouth bass (Micropterus dolomieui), Rs-challenged fish were eaten in significantly greater numbers than controls by nearly two to one. In 1994, we also sampled fish every 2 weeks after the challenge to determine some stressful effects of Rs infection. During disease progression in fish, plasma cortisol and lactate increased significantly whereas glucose decreased significantly. Our results indicate the role that BKD may play in predator-prey interactions, thus ascribing some ecological significance to this disease beyond that of direct pathogen-related mortality. In addition, the physiological changes observed in our fish during the chronic progression of BKD indicate that this disease is stressful, particularly during the later stages.

scholarly journals Metabolic constraints on long-distance migration in birds

1996 ◽  
Vol 199 (1) ◽  
pp. 57-64 ◽  
Author(s):  
M Klaassen
Keyword(s):  
Water Balance ◽  
Water Loss ◽  
Physiological Stress ◽  
Plasma Osmolality ◽  
Large Species ◽  
Long Distance ◽  
Flight Behaviour ◽  
Flight Range ◽  
Ecological Barriers ◽  
Balance Problems

The flight range of migrating birds depends crucially on the amount of fuel stored by the bird prior to migration or taken up en route at stop-over sites. However, an increase in body mass is associated with an increase in energetic costs, counteracting the benefit of fuel stores. Water imbalance, occurring when water loss exceeds metabolic water production, may constitute another less well recognised problem limiting flight range. The main route of water loss during flight is via the lungs; the rate of loss depends on ambient temperature, relative humidity and ventilatory flow and increases with altitude. Metabolite production results in an increased plasma osmolality, also endangering the proper functioning of the organism during flight. Energetic constraints and water-balance problems may interact in determining several aspects of flight behaviour, such as altitude of flight, mode of flight, lap distance and stop-over duration. To circumvent energetic and water-balance problems, a bird could migrate in short hops instead of long leaps if crossing of large ecological barriers can be avoided. However, although necessitating larger fuel stores and being more expensive, migration by long leaps may sometimes be faster than by short hops. Time constraints are also an important factor in explaining why soaring, which conserves energy and water, occurs exclusively in very large species: small birds can soar at low speeds only. Good navigational skills involving accurate orientation and assessment of altitude and air and ground speed assist in avoiding physiological stress during migration.

scholarly journals Stimulating release of undersized fish through a square mesh panel in the Basque otter trawl fishery

2020 ◽  
Vol 224 ◽  
pp. 105431
Author(s):  
Elsa Cuende ◽  
Luis Arregi ◽  
Bent Herrmann ◽  
Manu Sistiaga ◽  
Iñigo Onandia
Keyword(s):  
Otter Trawl ◽  
Trawl Fishery

Biologging in combination with biotelemetry reveals behavior of Atlantic salmon following exposure to capture and handling stressors

2019 ◽  
Vol 76 (12) ◽  
pp. 2176-2183
Author(s):  
Robert J. Lennox ◽  
Jacqueline M. Chapman ◽  
William M. Twardek ◽  
Franziska Broell ◽  
Kristin Bøe ◽  
...  
Keyword(s):  
Locomotor Activity ◽  
Atlantic Salmon ◽  
Null Model ◽  
Control Fish ◽  
Control Group ◽  
Sample Population ◽  
Accelerometer Data ◽  
Air Exposure ◽  
Data Loggers ◽  
Total Body

We investigated the response of Atlantic salmon (Salmo salar) to capture and handling stressors by analyzing fine-scale locomotor activity using accelerometer data loggers and broader-scale movements by tracking migration with radiotelemetry. Half the sample population was exposed to experimental exercise and air exposure and released with a control group to simulate fisheries handling. All but two of the surviving fish (both in the treatment group) returned to the counting fence to resume the 2016 spawning migration (survival = 86%–91%). There were no differences in postrelease locomotor activity, measured by an index of total body action (jerk), between control and treatment salmon (p = 0.81). Comparison of mean time to return to the counting fence against a null model revealed that treatment salmon were significantly delayed in returning to the counting fence (p < 0.01), whereas control fish were not (p = 0.24). Both the abiotic environment and human interactions influenced locomotor activity of the migratory fish and synchrony of the migration with untreated conspecifics.

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