Swimming Activity Levels Research Articles

Hatchery and wild larval lake sturgeon experience effects of captivity on stress reactivity, behavior and predation risk.

Reintroduction programs are important tools for wildlife conservation. However, captive rearing environments may lead to maladaptive behavior and physiological alterations that reduce survival probability after release. For captive rearing programs that raise individuals captured from the wild during early ontogeny for later release, there is a lack of information about when during ontogeny the detrimental effects of captive rearing may become evident. In this study we compared cortisol levels, predation rates and swimming behavior between hatchery-produced and wild-caught larval lake sturgeon (Acipenser fulvescens), a threatened fish species, at three times over 9 days. Cortisol levels did not indicate that hatchery-produced individuals were more stressed, but cortisol reactivity to an acute stressor disappeared for both hatchery-produced and wild-caught larvae after 9 days in the hatchery. Swimming activity levels decreased over time for hatchery-produced larvae but increased over time for wild-caught larvae, suggesting that behavioral trajectories may be programmed prior to the larval stage. Neither increasing nor decreasing activity levels was advantageous for survival, as predation rates increased over time in captivity for larvae from both treatments. Results suggest that physiological and behavioral phenotypes may not accurately predict survival for individuals released from reintroduction programs and that the captive environment may inhibit transition to the wild even if cortisol levels do not indicate high stress. Findings emphasize that even a short amount of time in captivity during early ontogeny can affect phenotypes of individuals captured from wild populations, which may impact the success of reintroduction programs.

New insights into methylmercury induced behavioral and energy-related gene transcriptional responses in European glass eel (Anguilla anguilla)

The effect of methylmercury (MeHg) was investigated in glass eel migration behavior and metabolism. To migrate up estuary, glass eels synchronize their swimming activity to the flood tide and remain on or in the substratum during ebb tide. Following seven days of exposure to MeHg (100 ng L−1), glass eels migration behavior was expressed by their swimming synchronization to the water current reversal every 6.2 h (mimicking the alternation of flood and ebb tides) and their swimming activity level. In relation to their behavior, we then analyzed the energy-related gene expression levels in individual head, viscera and muscle. Results showed that MeHg decreased the number of glass eels synchronized to the change in water current direction and their swimming activity level. This last effect was more pronounced in non-synchronized fish than in synchronized ones, supporting the idea that non-synchronized glass eels could be more vulnerable to stress. As regard the expression of energy-related genes, no significant difference was observed between control and MeHg-exposed fish. In contrast, when the swimming activity levels were plotted against transcriptional responses, positive correlations were evidenced in viscera and especially in the head of exposed glass eels but not in control. Finally, it is noteworthy that non-synchronized glass eels displayed lower expression level of metabolism genes than their synchronized counterpart, but only in the head. Altogether, these results support the interest of focusing on the head to investigate the facultative migration behavior in glass eels and the effect of environmental stressors on this rhythmic behavior.

Looking at the complex relationships between migration behavior and conditional strategy based on energy metabolism in the European glass eel (Anguilla anguilla)

Diadromy in eel is facultative and the diverse propensities in glass eel estuarine migration may lead to a large spatial dispersion, which may has profound influences on the species sex determination. In this study, we sought to clarify the relationship between European glass eel energetics and their pattern of migration behavior, in the framework of the conditional strategy. Marine glass eels were sampled in autumn and spring, stratifying high and low energetic status, respectively. Their migration behavior was determined in experimental installations that mimic tides using a change in water current direction every 6.2 h. When synchronized to the current reversal, glass eels were called active while individuals hiding in the substratum were considered as non-active. Then, for each active fish, a level of swimming activity was determined and both migration behavior and level of swimming activity were correlated to the individual wet weight (used as a proxy of energy stores), standard metabolic rate (relative SMR) and transcriptomic profile of metabolism related genes. Results showed that spring glass eels presented a lower probability to migrate, a lower wet weight and a higher expression of genes involved in energy stress resistance than autumn ones, supporting a conditional strategy based on individual's energy status. However, within each season, no wet weight difference was observed between active and non-active fish. In autumn glass eels, migration behavior was weakly related to relative SMR while in spring, none of the parameters analyzed allows discriminating active and non-active glass eels. The level of swimming activity in active fish was related to their relative SMR in autumn and to their wet weight in spring. Altogether, our results could not validate a conditional strategy but spring glass eels displayed some signs of energy distress and a lower level of swimming activity than autumn ones.

Using acoustic telemetry to monitor the effects of crowding and delousing procedures on farmed Atlantic salmon (Salmo salar)

The aim of this study was to demonstrate the feasibility of acoustic telemetry for monitoring fish during farm operations and gather knowledge about Atlantic salmon responses during crowding and delousing events in a commercial sea-cage. 21 fish were equipped with a novel transmitter tag type using data from pressure sensors and accelerometers to compute swimming depth and swimming activity of individual fish. The fish were monitored over four months, during which they were subjected to three thermal delousing events. In the periods before and after delousing, the fish generally exhibited a circadian rhythm in both swimming activity and depth, with high activity and deep swimming during daytime and low activity and shallow swimming during night. Swimming activity recorded during crowding and delousing events was significantly higher than background swimming activity levels registered a day before and after delousing. Although activity levels differed significantly between the three events and between the different stages within each event, the highest activity levels were consistently measured during thermal treatment. Swimming depth differed significantly between delousing events and was strongly influenced by daylight. In summary, crowding and delousing induced increased movement in the fish, while swimming depth appeared to be less sensitive to these operations. The conclusion of the study is that acoustic telemetry is a suitable tool for monitoring fish during challenging operations such as crowding and delousing, as well as during normal cage management. Moreover, this study provides new knowledge on how the behaviour of Atlantic salmon may be affected by delousing.

Effect of an alien turtle predator on movement activity of European brown frog tadpoles

An increasing amount of attention has been devoted to studying the impact of non-native plant and animal species on native species. In this paper, we examined the antipredator response of naïve European brown frog (Rana temporaria Linnaeus, 1758) tadpoles to water-borne chemical cues from invasive red-eared slider turtles (Trachemys scripta elegans Wied, 1838) in the presence and the absence of conspecific tadpoles. The level of swimming activity was expressed as the length of the tadpoles’ trajectory. The tadpoles showed a decrease in swimming activity when predator stimuli were present, which was highly significant when the tadpoles were measured individually and did not have contact (visual and chemical) with other tadpoles. In the absence of chemical cues of slider turtles, the presence of other tadpoles had no effect on the level of swimming activity. Moreover, for the first time in tadpoles, we found that the decrease in swimming activity was also accompanied by changes in swimming trajectory, with tadpoles exposed to predator cues swimming in more zigzagged trajectories. Our experiment shows that invasive slider turtles, as a novel predator, have a measurable influence on the swimming behaviour of European brown frog tadpoles. Consequences of the reduced swimming activity of tadpoles, like its impact on growth, are discussed.

Nano-tags for neonates and ocean-mediated swimming behaviours linked to rapid dispersal of hatchling sea turtles.

Dispersal during juvenile life stages drives the life-history evolution and dynamics of many marine vertebrate populations. However, the movements of juvenile organisms, too small to track using conventional satellite telemetry devices, remain enigmatic. For sea turtles, this led to the paradigm of the 'lost years' since hatchlings disperse widely with ocean currents. Recently, advances in the miniaturization of tracking technology have permitted the application of nano-tags to track cryptic organisms. Here, the novel use of acoustic nano-tags on neonate loggerhead turtle hatchlings enabled us to witness first-hand their dispersal and behaviour during their first day at sea. We tracked hatchlings distances of up to 15 km and documented their rapid transport (up to 60 m min(-1)) with surface current flows passing their natal areas. Tracking was complemented with laboratory observations to monitor swimming behaviours over longer periods which highlighted (i) a positive correlation between swimming activity levels and body size and (ii) population-specific swimming behaviours (e.g. nocturnal inactivity) suggesting local oceanic conditions drive the evolution of innate swimming behaviours. Knowledge of the swimming behaviours of small organisms is crucial to improve the accuracy of ocean model simulations used to predict the fate of these organisms and determine resultant population-level implications into adulthood.

Food-search strategy in ling (Molva molva L.): crepuscular activity and use of space.

The activity rhythm and use of space in the food-searching behaviour of ling (Molva molva L.) were studied by means of a stationary positioning system. The system consisted of a fixed array of three hydrophones, which monitored the position of each individual being tracked once every three minutes. Five ling were tagged in situ by allowing them to ingest a transmitter wrapped in bait and were tracked continuously for 6 to 11 days. Ling showed a crepuscular activity rhythm with higher levels of swimming activity at dawn and dusk. The fish occupied a home range throughout the study, and during inactive periods (about 65% of the time) they remained within a small core area. Most of the time spent outside the core area was during the period of high activity at dawn. Food-search behaviour was studied by setting mackerel-baited fishing gear in the experimental area. When baits were present, ling moved more slowly and within a more limited area, indicating area-restricted searching in the presence of a food odour. Ling responded to and located baits in both their active and inactive periods during the day, but were not observed to react at night. Comparing these findings with those from similar tracking experiments on cod (Gadus morhua L.) suggested that ling are less active at night and show a more restricted use of space by occupying a core area. This may reflect different feeding strategies between these gadoid species with ling taking a higher proportion of mobile prey and being more dependent on visual stimuli.

Use of an Acoustic Beam Actograph to Assess the Effects of External Tagging Procedure on Lake Whitefish Swimming Activity

Abstract We conducted laboratory tests on the effects of externally applied acoustic tags on the swimming activity of lake whitefish Coregonus clupeaformis. Using an acoustic beam actograph, we evaluated the swimming activity patterns of 15 fish over a 40-d period and tagged 12 of the fish at mid-experiment, after 20 d. Fish activity was continuously recorded by counting the number of beam interruptions per hour. Before fish were tagged, the activity pattern of 8 of the 15 fish showed more activity during the day than at night; 5 fish were equally active during day and night, and 2 fish were predominantly active at night. After they were tagged, one control (33%) and seven tagged fish (58%) kept the same activity pattern. A consistency in day and night swimming activity levels was observed between the two periods for two control fish and two tagged fish. Day activity levels before or after the tagging date were not statistically different between the three groups tested (control, small and large fish), wh...

Diel activity rhythm of seabass tracked in a natural environment: group effects on swimming patterns and amplitudes

Seabass swimming behavior was investigated in a salt-marsh area located along the Atlantic coast north of La Rochelle, France. Seabass is a natural inhabitant of this coastal zone and is farmed there as well. During its 3rd year, seabass can move about either singly or in small groups. Swimming activity of single fish and fish in a group was studied using an acoustic telemetry recording system. This study demonstrates that swimming activity levels and patterns of this species are modified by a group effect. Single fish were mainly nocturnal and fish in a group adopted a diurnal activity rhythm and lower maximum swimming activity levels.

The Ontogeny of Antipredator Behaviour in Paradise Fish Larvae (Macropodus opercularis): The Recognition of Eyespots

AbstractThe ontogeny of antipredator behaviour of paradise fish was examined using a simple testing method. The results showed that the ability to recognize eyespots appears in larvae between 15 and 20 days old. At the same time, two horizontally placed eyespots produced the most pronounced effect on the behaviour of the larvae. Testing different inbred strains revealed that the ontogeny of antipredator behaviour is also under broad genetic control, as the response to a model predator was strong in one strain but weak in another. The results suggest that the recognition of eyespots coincides with larvae becoming more conspicuous to predators by the appearance of pigmentation and increasing level of swimming activity (exploration).

Role of genotype and dopamine receptors in behaviour of inbred mice in a forced swimming test

The role of genotype in the effects of selective D1 and D2 dopamine agonists and antagonists on behavioural despair (Porsolt's test) was studied. Mice of nine inbred strains showed significant interstrain differences in duration of immobility. The influence of dopaminergic drugs was assessed in six strains characterized by different levels of swimming activity. SKF 38393 (10 mg/kg), an agonist at D1 dopamine receptors, increased swimming activity, while the D1 antagonist SCH 23390 (0.2 and 0.5 mg/kg) reduced it, the effects being genotype dependent. The involvement of D2 dopamine receptors in the regulation of mouse behaviour in the forced swimming test was not so evident; the D2 agonist bromocriptine (10 mg/kg) produced no significant effect. The D2 agonist quinpirole (2.5 mg/kg) increased immobility in the majority of the mouse strains studied, while in CBA mice it resulted in a marked reduction of immobility. The D2 antagonist sulpiride (20 mg/kg) decreased immobility and increased active swimming only in two strains. The present results suggest a different role for D1 and D2 dopamine receptors in the regulation of swimming in the mouse.

Habitat use and feeding behavior of thirteen species of benthic stream fishes

The densities, habitat use, and feeding behaviors of 13 fish species belonging to the benthic invertebrate-feeding guild were studied by snorkeling at three localities in the Little River of eastern Tennessee, U.S.A. Resource partitioning occurred by habitat, feeding behavior and time of activity. Differences were also found at the generic level.Cottus was a nocturnal feeder, whereasPercina andEtheostoma were, for the most part, diurnally active.Percina moved about rapidly and spent most of its time above the bottom. In contrast,Etheostoma varied considerably in the amount of time spent under cover, spent little time above the bottom, and exhibited low levels of swimming activity. Nearly all species sought cover at night, suggesting they may be particularly sensitive to predation at night. Species with small adult sizes (Etheostoma, Cottus andP. evides) were concentrated in shallow water habitats, whereas species with large adult sizes (Percina) were more abundant in deep water habitats. The habitat use data are consistent with the hypothesis that size-selective predation by centrarchid bass may cause smaller fish to avoid deep water areas. Large species should have a lower risk of predation due to their size and behavior.

A method for the quantitative evaluation of fish movements in salt ponds by acoustic telemetry

Previously used in metallurgy, the acoustic positioning system has been adapted in this work for fish tracking. Details of methodology, accuracy of the information derived and limitations of the technique are described. Experimental evaluation of the constant of error as allocated per unit area (e.g., ·m −2) enabled estimation of the maximal error in the distance travelled and provided accurate comparison of the swimming activities of different specimens. The tracking system as outlined here can be satisfactorily used to study fish behaviour in ponds, with special reference to habitat utilization and levels of swimming activity linked to natural variations in the environment.

Use of Adenylate Concentrations and Adenylate Energy Charge as Indicators of Hypoxic Stress in Estuarine Fish

Normal ATP concentrations in the white muscle of 11 different estuarine fish species varied from 3.91 to 6.59 μmol/g. Concentrations of different adenylates in the white muscle were not related to a species' natural level of swimming activity. When fish were exposed to hypoxia, ATP concentrations declined as much as 72% in some species. Decreases in ATP were not reflected in stoichiometric increases in ADP or AMP but rather in a reduction in total adenylate concentration. Sensitivity to hypoxia, expressed as changes in adenylate concentrations, was related to a species' natural level of activity and habitat preference. ATP concentration, total adenylate concentration, and adenylate energy charge appear to be useful indicators of environmental stress.Key words: ATP, energy charge, hypoxia, stress assessment

Behavioural studies on the lesser sandeel Ammodytes marinus (Raitt) II. The effect of light intensity on activity

The behaviour of the lesser sandeel, Ammodytes marinus (Raitt), has been investigated at light intensities of 1, 10, 100 and 1000 lux, using a photographic method of recording activity. The level of swimming activity was high at 1000 and 100 lux, declining to a very low level at 1 lux. It was concluded that this was due to the limiting effect of light on feeding. The threshold light intensity for swimming activity in the tank was estimated as being approximately 20 lux but it was considered that in the area of the sandeel fishing grounds the threshold might be higher than this, in the region of 100 lux. The number of hours light per day above 20 and 100 lux at a depth of 15 m in the area of the Outer Dowsing sandbank (53°30′N, 01°00′E) was estimated for the various months of the year. It was shown that during the winter the light intensity does not normally reach 100 lux and only exceeds 20 lux for a few hours each day. It is suggested that this could limit swimming activity and accessibility at this time of year. Measurements were made of the penetration of light into sand and it was concluded that fish which are buried might be able to detect light, possibly via the pineal gland.

Behavioural studies on the lesser sandeel Ammodytes marinus (Raitt) III. The effect of temperature on activity and the environmental control of the annual cycle of activity

The behaviour of the lesser sandeel, Ammodytes marinus (Raitt), has been investigated at 5, 10 and 15° C, using a photographic method of recording activity. The activity patterns at 10 and 15° C were very similar, there being a high level of swimming activity during the light period, which fell to a low level at 5° C. It was also lower at 10° C at the end of the experiment than at the beginning and it is suggested that this might have been due to an increase in the fat contents of the fish. The feeding rate of the fish was measured and showed a Q10 of 2.08 for the temperature range 5–15° C. The annual cycle of activity of A. marinus is discussed in relation to seasonal changes in food availability, light and temperature, and in the fat content of the fish. It is concluded that after spawning in the December–January period the fish remain buried in the sand until April, because of the limiting effect on swimming and feeding activity of the environmental factors in the intervening period. The proportion of fish available for capture at the start of the fishery in April is related mainly to temperature, but food (as measured by numbers of copepods) light intensity and photoperiod are by then increasing rapidly. After July the fishery ceases and it is thought that this is because the fish have entered an overwintering stage, during which they remain buried in the sand. This phase is also thought to be associated with the maturation of the gonads in readiness for the winter spawning. The factors causing the fish to enter this stage are as yet undetermined but may be related to the attainment of a certain level of fat content.

Behavioural studies on the lesser sandeel Ammodytes marinus (Raitt) I. The effect of food availability on activity and the role of olfaction in food detection

The behaviour of the lesser sandeel, Ammodytes marinus (Raitt), has been investigated using a photographic method of recording activity. Three main states of activity were recognized: (1) swimming, (2) partially emerged from the sand, or (3) completely buried in the sand. When food was present there was a basic diurnal rhythm of activity; during the dark period most of the fish remained buried in the sand and in the light period they emerged to swim and feed. In the absence of food the level of swimming activity during the light period was extremely low, while the level of partial emergence activity increased. The fish appear to be visual feeders and those which were buried in the sand did not appear to be able to detect the presence of food in the water by means of olfaction. There was usually a low level of partial emergence activity during the dark period, which tended to increase in the few hours before the lights were switched on. The timing of this increase was thought to be related to an internal clock. The basic diurnal rhythm of activity shown in the laboratory experiments is discussed in relation to the marked diurnal variation in the catch of sandeels in the fishery. It is concluded that the failure to catch sandeels at night is due to their remaining buried in the sand.

Influence of Environmental Experience on Response of Yearling Rainbow Trout (Salmo gairdneri) to a Black and White Substrate

Yearling rainbow trout (Salmo garidneri) selected black substrate regardless of size or rearing experience when first introduced into an experimental tank offering a choice of black or white. Differences in the degree of black selection among the various lots of the same strain during the initial 120 min of exposure, under an illumination of 10−2 lx, were correlated only with the level of swimming activity. By 24 hr, only pond-rearsd fish continued to select black while laboratory-reared fish were randomly distributed over black and white. The continuing wariness of only the pond-reared fish reveals the long-term effect of prior experience on juvenile trout behavior. This finding indicates the possible feasibility of environmental conditioning for wariness in the artificial propagation of hatchery-reared fish for live release.

A small sonic tag for measurement of locomotor behaviour in fish

A technique for measuring the patterns and levels of swimming activity of unrestrained fish in their natural environment during a period of 24 h is described. The fish were marked with small tags which emitted continuous ultrasonic signals by which they could be located and tracked using submerged, remotely controlled, directional hydrophones. Preliminary results obtained from 2 brown trout (Sahno trutta) showed a pronounced diurnal activity pattern and remarkably low swimming activity levels.