Detection of feeding behaviour in common carp Cyprinus carpio by using an acceleration data logger to identify mandibular movement

Miniaturized acceleration data loggers were attached to the lower mandible of common carp Cyprinus carpio to remotely identify feeding behaviour. Whether the acceleration signal could distinguish the quantity and quality of food was also investigated. The frequency and amplitude of the lower mandible stroke, calculated from surging acceleration determined by continuous wavelet transformation, significantly increased during the feeding period compared to that during the non-feeding period. These characteristic movement patterns were maintained for mean ±s.e. 187·3 ± 38·2 s when the fish were fed a single item of food and for mean ±s.e. 419·3 ± 28·6 s when they consumed multiple items. The dominant cycle and amplitude calculated according to feeding event duration, however, did not differ significantly between the two types of diets the fish consumed. Surging acceleration could detect mean ±s.e. 89·8 ± 13·5% of feeding events, although the false detection rate was mean ±s.e. 25·9 ± 10·9%. The results indicate that the mandible acceleration measurement method could be utilized to detect and record the feeding events in fishes that use a suction feeding mode similar to C. carpio.     

Reproductive behavior of the Lake Malawi cichlid fish, <Emphasis Type="Italic">Tramitichromis intermedius</Emphasis>

Synopsis We studied the reproductive behavior of wild caught and captive-born, first generation offspring of the Lake Malawi fish, Tramitichromis intermedius(Teleostei, Cichlidae), held in aquaria. Spawning behavior includes an exchange of actions with dominant males performing bower construction and courtship behaviors while females focus on oviposition and mouthbrooding. Egg counts per oviposition and brooding and interbrooding periods of wild caught T. intermedius follow records of other mouthbrooding cichlid fishes. Observation of circling behavior suggests this behavioral trait may be used in mate choice as longer circling, indicating a secure territory and thus male dominance, leads to more oviposition events and hence the potential for larger broods. Comparisons of clutch size and total length of young at release from full-sized females vs. first spawners reveal smaller clutches and young from the younger females, most likely stemming from differences in body size. Investigation of spawning photoperiodicity also noted distinctions between the two groups with wild caught T. intermedius spawning activity peaking in the middle of the light cycle and captive-born, first spawners exhibiting no significant peak in activity. The trend to spawn midday is most likely influenced by predation factors, while the lack of a spawning periodicity in the offspring may be explained by developmental processes, the absence of environmental cues or the tendency for smaller males to be opportunistic in spawning events. The details of spawning behavior recorded in this study provide a database to investigate species differences and to indicate changes due to chemical and physical disturbances.     

Spawning strategies in cypriniform fishes in a lowland river invaded by non-indigenous European barbel Barbus barbus

Spawning strategies of lowland river fishes include single spawning, where reproduction generally occurs in early spring to provide 0+ fish with an extended growth season through the summer, but with a high risk of stochastic mortality events occurring, such as early summer floods. This risk can be reduced by multiple or protracted spawning strategies, where 0+ fish are produced over an extended period, often into mid-summer, but with the trade-off being a shorter growth season. The spawning strategies of cypriniform fish were explored in the River Teme, a spate river in Western England, which has non-indigenous European barbel Barbus barbus present. Sampling 0+ fish in spring and summer and across three spawning periods, B. barbus, chub Squalius cephalus and minnow Phoxinus phoxinus always revealed multiple spawning events, with 0+ fish of < 20 mm present in samples collected from June to August. Fish below 20 mm in August remained relatively small by the end of their growth season (October). For dace Leuciscus leuciscus, only single spawning events were evident, but with 0+ dace always being relatively large. Therefore, multiple spawning appears to be a common strategy that provides resilience in 0+ fish against stochastic mortality events in lowland rivers.

     

Social Behaviour of Individual Oval Squids (Cephalopoda,Teuthoidea, Loliginidae,Sepioteuthis lessoniana) within a Captive School

The social behaviour of individually identified squids was observed over a period of 4 mo. Squids were reared in captivity and maintained in a shoal of up to 18 animals. Distances between animals averaged 1.6 body lengths, similar to the 1.2 body lengths of wild teleost fish schools. Smaller animals schooled less frequently and were found at the periphery, and familiar and unfamiliar animals shoaled together. Eighty-six apparent reproductive events were observed. This species of squid, Sepioteuthis lessoniana, is not sexually dimorphic to the human eye and male squids copulated with both males and females but they directed their attention disproportionately towards females. Most copulations occurred more than a month before spawning, lasted only a few seconds and, unlike field observations on spawning grounds, were not followed by mate-guarding. Two body patterns are described that were used consistently in social interactions by both males and females; these patterns were both associated with reproductive behaviour but their exact function was unclear. A sister species, Sepioteuthis sepioidea, has been described as showing complex social behaviour; in S. lessoniana, no evidence for such behaviour was seen.     

The spawning behaviour of the endangered freshwater fish Ladigesocypris ghigii (Gianferrari, 1927)

Ladigesocypris ghigii (Gianferrari, 1927), commonly called gizani, is an endangered freshwater fish endemic to the Greek island of Rhodes. The spawning behaviour of gizani was studied in aquaria, to develop an artificial breeding technique for this endangered species. Spawning in captivity was recorded over 41 spawning days between 15 February and 14 July 2001, under constant temperature (18 or 21°C) and photoperiod 14L/10D. The number of spawning acts in a day was 82 ± 28. No aggressiveness and no territoriality were developed. The mating system of the fish was polygamous, with females spawning more than once. In captivity, eggs are laid either on aquatic plants or on gravel, while in nature fish spawn mainly on algae and plants. The latter suggests that, as far as breeding substrate is concerned, gizani is an opportunistic species using different substrates when necessary.     

Patterns of Aggression and Operational Sex Ratio Within Alternative Male Phenotypes in Atlantic Salmon

The intensity of male–male aggression during mating is predicted to increase with the operational sex ratio (OSR) (the ratio of sexually active males to females). We observed aggressive behaviour in relation to OSR within alternative phenotypes (large anadromous males and small ‘sneaker’ mature male parr) of Atlantic salmon, Salmo salar, as they competed for access to anadromous females in large outdoor arenas immediately prior to spawning events as well as throughout the spawning season. Anadromous males were primarily aggressive outside of spawning events, and their aggression increased with OSR over a narrow range of 0.08–4. By contrast, mature male parr were aggressive just prior to spawning, with a decrease in aggression over a broad range of OSRs from 1 to 7.4. Similarly, literature data for three other salmonid species indicated a decrease in aggression with increasing OSRs over a range of 1–6.33. These observations suggest that there is considerable variability in competitive behaviour, even within alternative phenotypes. Because our data are derived from repeated observations on the same individuals of different genetic origin, further confirmation of these findings is desirable. Nevertheless, our study underscores the importance of measuring competitive behaviour and OSR at ecologically relevant spatial and temporal scales, both of which may differ between alternative maturation phenotypes.     

Spawning behaviour ofCheimerius nufar in captivity

Synopsis The santerCheimerius nufar is widespread in tropical and subtropical waters of the western Indian Ocean and forms an important component of linefish catches along the east coast of southern Africa. Observations of spawning behaviour in captivity have revealed that spawning occurs during spring over a period of four months. Mating takes place at sunrise and may continue for up to 105 min (mean duration = 60 min). During spawning males become dark with prominent white markings. They become very aggressive and set up territories. Females remain a uniform silvery-pink. Mating occurs between males and females of similar sizes, culminating in egg and sperm release near the surface. Individual fish spawned up to 14 times during a morning. Streaking occurred throughout the season, with a second male joining a spawning pair and releasing gametes simultaneously. Slinger,Chrysoblephus puniceus, a dominant fish on offshore reefs in the same region, interfered with spawning throughout the season and were observed to eat eggs when they were released. The spawning strategy ofC. nufar is similar to protogynous species in several respects, indicating that this functional gonochorist may not conform to current theoretical predictions.     

Spawning behaviour of Allis shad Alosa alosa: new insights based on imaging sonar data

Spawning behaviour of Alosa alosa was observed by high resolution imaging sonar. Detected clouds of sexual products and micro bubbles served as a potential indicator of spawning activity. Peak spawning time was between 0130 and 0200 hours at night. Increasing detections over three consecutive nights were consistent with sounds of mating events (bulls) assessed in hearing surveys in parallel to the hydro acoustic detection. In 70% of the analysed mating events there were no additional A. alosa joining the event whilst 70% of the mating events showed one or two A. alosa leaving the cloud. In 31% of the analysed mating events, however, three or more A. alosa were leaving the clouds, indicating that matings are not restricted to a pair. Imaging sonar is suitable for monitoring spawning activity and behaviour of anadromous clupeids in their spawning habitats.     

Breeding Tubercles, Papillomatosis and Dominance Behaviour of Male Roach (Rutilus rutilus) During the Spawning Period

We studied the relationship between the breeding tubercle ornamentation (i.e. skin roughness) and male pre‐spawning dominance and courtship behaviour in roach (Rutilus rutilus) within an experimental laboratory system. Sexually mature fish were caught during their migration to their spawning pond and their behaviours were studied in an artificial spawning arena. Males behaved naturally both in terms of male–male interactions and attempts to achieve spawnings. Males having many, large breeding tubercles (i.e. rough skin) were significantly more often dominant in our dyadic trials than those with smooth skin. The dominant male in the trial exhibited a more active courtship behaviour than its subordinate rival. Papilloma skin disease did not affect the dominance rank. As a result of the relationship between skin roughness and male dominance, breeding tubercles may be used by the females as a cue for choosing a high‐quality mate in a roach lek. Thus, breeding tubercles might offer a workable tool for examination of sexual selection among cyprinids.     

Effects of Hurricane Charley on fish chorusing

Hurricane Charley, a category 4 hurricane, passed through Charlotte Harbor, Florida, directly over an autonomous underwater acoustic datalogger used to record sound production by fishes associated with courtship and spawning. Acoustic recordings made on 9 days prior to the storm, during and 3 days after the storm provided unprecedented documentation of the hurricane's passage and its effect on fishes' calling behaviour. The hurricane did not inhibit nightly chorusing events of spawning fish. Sound levels produced by spawning fish on the night of and 3 days after the hurricane were higher and lasted longer than any of the 9 days recorded prior to the hurricane.     

The scaling of locomotor performance in predator-prey encounters: from fish to killer whales.

During predator-prey encounters, a high locomotor performance in unsteady manoeuvres (i.e. acceleration, turning) is desirable for both predators and prey. While speed increases with size in fish and other aquatic vertebrates in continuous swimming, the speed achieved within a given time, a relevant parameter in predator-prey encounters, is size independent. In addition, most parameters indicating high performance in unsteady swimming decrease with size. Both theoretical considerations and data on acceleration suggest a decrease with body size. Small turning radii and high turning rates are indices of maneuverability in space and in time, respectively. Maneuverability decreases with body length, as minimum turning radii and maximum turning rates increase and decrease with body length, respectively. In addition, the scaling of linear performance in fish locomotion may be modulated by turning behaviour, which is an essential component of the escape response. In angelfish, for example, the speed of large fish is inversely related to their turning angle, i.e. fish escaping at large turning angles show lower speed than fish escaping at small turning angles. The scaling of unsteady locomotor performance makes it difficult for large aquatic vertebrates to capture elusive prey by using whole-body attacks, since the overall maneuverability and acceleration of small prey is likely to be superior to that of large predators. Feeding strategies in vertebrate predators can be related to the predator-prey length ratios. At prey-predator ratios higher than approximately 10(-2), vertebrate predators are particulate feeders, while at smaller ratios, they tend to be filter feeders. At intermediate ratios, large aquatic predators may use a variety of feeding methods that aid, or do not involve, whole body attacks. Among these are bubble curtains used by humpback whales to trap fish schools, and tail-slapping of fish by delphinids. Tail slapping by killer whales is discussed as an example of these strategies. The speed and acceleration achieved by the flukes of killer whales during tail slaps are higher and comparable, respectively, to those that can be expected in their prey, making tail-slapping an effective predator behaviour.     

Classifying and inferring behaviors using real‐time acceleration biotelemetry in reproductive steelhead trout (Oncorhynchus mykiss)

Movement behaviors are central to ecology and conservation. Movement sensing technologies can monitor behaviors that are otherwise difficult to observe under field conditions and may enhance the ability to quantify behaviors at the population scale. We monitored steelhead trout (Oncorhynchus mykiss) spawning behaviors in a seminatural enclosure using accelerometer telemetry tags while simultaneously observing behaviors with underwater cameras. Behavioral assignments from visual observations were compared to acceleration histories to develop assignment criteria for acceleration data, including for a key behavior (oviposition). Behavioral events independently classified using acceleration data prior to reviewing video were compared to video scoring and 97% of holding behaviors, 93% of digging behaviors, and 86% of oviposition/covering behaviors were correctly assigned using acceleration data alone. We applied the method to at‐liberty steelhead in spawning tributaries. Acceleration records revealed putative spawning and oviposition in at‐liberty female steelhead, and time budgets for at‐liberty steelhead were similar to those monitored within enclosures. The use of similar movement sensing tags and classification approaches offers a method for monitoring movement behavior, activity budgets, and habitat use in a broad array of aquatic and terrestrial taxa, and may be especially useful when behaviors are cryptic.     

Recovery from a fish kill in a semi‐arid Australian river: Can stocking augment natural recruitment processes?

Localized catastrophic events can dramatically affect fish populations. Management interventions, such as stocking, are often undertaken to re‐establish populations that have experienced such events. Evaluations of the effectiveness of these interventions are required to inform future management actions. Multiple hypoxic blackwater events in 2010–2011 substantially reduced fish communities in the Edward‐Wakool river system in the southern Murray‐Darling Basin, New South Wales, Australia. These events led to extensive fish kills across large sections of the entire system following a period of prolonged drought. To expedite recovery efforts, 119 661 golden perch Macquaria ambigua and 59 088 Murray cod Maccullochella peelii fingerlings were stocked at five locations over 3 years. All fish stocked were chemically marked with calcein to enable retrospective evaluation of wild or hatchery origin. Targeted collections were undertaken 3 years post‐stocking to investigate the relative contribution of stocking efforts and recovery via natural recruitment in the system. Of the golden perch retained for annual ageing (n = 93) only nine were of an age that could have coincided with stocking activities. Of those, six were stocked. The dominant year‐class of golden perch were spawned in 2009; before the stocking programme began and prior to blackwater events. All Murray cod retained (n = 136) were of an age that coincided with stocking activities, although only eight were stocked. Among the Murray cod captured, the dominant year‐class was spawned in 2011, after the blackwater events occurred. The results from this study provide first evidence that natural spawning and recruitment, and possibly immigration, were the main drivers of golden perch and Murray cod recovery following catastrophic fish kills. Interpreted in the context of other recent examples, the collective results indicate limited benefit of stocking to existing connected populations already naturally recruiting in riverine systems.     

Polygynous Mating System of Trimma okinawae (Pisces: Gobiidae) at Kagoshima,Japan with a Note on Sex Change

Mating system, social structure and reproductive behaviour of the gobiid fish Trimma okinawae were studied at Akamizu, Kagoshima, Japan. Mating system of this species is polygyny. There were two types of habitat-related distribution patterns of male and female home ranges: females have home ranges outside a small territory of the male; female home ranges are covered by male territory. Spawnings take place with a cycle of four to five days during the spawning season of June to Sept. In the morning of the day of spawning, males stay at the spawning sites. Females visit the site and spawn with the male. On days between spawnings males exhibit courtship displays at female home ranges. Higher reproductive success is not connected with frequency of such courting of the male, but with male size. The largest female of a social unit changes into a male when the dominant male is removed, which shows that T. okinawae is a hermaphrodite.     

Melatonin in the Regulation of Annual Testicular Events in Carp Catla catla: Evidence from the Studies on the Effects of Exogenous Melatonin,Continuous Light,and Continuous Darkness

The physiological significance of melatonin in the regulation of annual testicular events in a major carp Catla catla was evaluated through studies on the effects of graded dose (25, 50, or 100 µg/100 g body wt.) of melatonin exogenously administered for different durations (1, 15, or 30 days) and manipulation of the endogenous melatonin system by exposing the fish to constant darkness (DD) or constant light (LL) for 30 days. An identical experimental schedule was followed during the preparatory (February–March), pre‐spawning (April–May), spawning (July–August), and post‐spawning (September–October) phases of the annual cycle. Irrespective of the reproductive status of the carp, LL suppressed while DD increased the mid‐day and mid‐night values of melatonin compared to respective controls. Influences of exogenous melatonin varied in relation to the dose and duration of treatment and the reproductive status of the carp. However, testicular response to exogenous melatonin (at 100 µg, for 30 days) and DD in each reproductive phase was almost identical. Notably, precocious testicular maturation occurred in both DD and melatonin‐injected fish during the preparatory phase and in LL carps during the pre‐spawning phase. In contrast, testicular functions in both the melatonin‐treated and DD fish were inhibited during the pre–spawning and spawning phases, while the testes did not respond to any treatment during the post‐spawning phase. In conclusion, this study provided the first experimental evidence that melatonin plays a significant role in the regulation of annual testicular events in a sub‐tropical surface‐dwelling carp Catla catla, but the influence of this pineal hormone on the seasonal activity of testis varies in relation to the reproductive status of the concerned fish.     

Monitoring Escape and Feeding Behaviours of Cruiser Fish by Inertial and Magnetic Sensors

A method was developed and applied for monitoring two types of fast-start locomotion (feeding and escape) of a cruiser fish, Japanese amberjacks Seriola quinqueradiata. A data logger, which incorporated a 3-axis gyroscope, a 3-axis accelerometer and a 3-axis magnetometer, was attached to the five fish. The escape, feeding and routine movements of the fish, which were triggered in tank experiments, were then recorded by the data logger and video cameras. The locomotor variables, calculated based on the high resolution measurements by the data logger (500 Hz), were investigated to accurately detect and classify the types of fast-track behaviour. The results show that fast-start locomotion can be detected with a high precision (0.97) and recall rate (0.96) from the routine movements. Two types of fast-start movements were classified with high accuracy (0.84). Accuracy was greater if the data were obtained from the data logger, which combined an accelerometer, a gyroscope and a magnetometer, than if only an accelerometer (0.80) or a gyroscope (0.66) was used.     

Microsatellites from the burbot (Lota lota), a freshwater gadoid fish (Teleostei)

We developed 21 polymorphic dinucleotide microsatellite loci, (CA)_n and (CT)_n, for the Holarctic freshwater fish, Lota lota, using an enriched genomic library protocol. The species has an interesting life history because winter‐spawning adults migrate over long distances to form spawning aggregations, a behaviour which should maintain genetic homogeneity across large spatial scales. Availability of the reported microsatellites will facilitate the investigation of population genetic structure with regard to postglacial colonization history and conservation strategies. The primers were screened on 30 individuals from a natural population (Lake Constance, southern Germany), revealing three to 24 alleles per locus with expected heterozygosities ranging from 0.48 to 0.93.     

The migratory behaviour of North Sea plaice: Currents, clocks and clues

Water currents are a dominant feature of the open sea and often play an important part in the life cycle of the fish that live there. For over three decades, a focus of research at Lowestoft has been the role of tidal water currents as a part of wider understanding of the population dynamics of plaice (Pleuronectes platessa) in the North Sea. Increasingly sophisticated telemetry methods have been developed and used, initially to describe the migratory behaviour of individual fish, and latterly to describe the spatial dynamics of whole populations. Here, the authors review cues and clues for environmental transport at different life stages, with a critical evaluation of the facultative use of selective tidal stream transport in relation to water current speed. The clues that trigger movement into mid-water by adult fish are reconsidered in light of new findings. Finally, the orientation capabilities of plaice, together with evidence of repeat migrations and spawning site fidelity were examined.     

Breeding antarctic krill in captivity

Antarctic krill were maintained in large aquaria at Port of Nagoya Aquarium, Japan, under controlled photoperiod and were fed on phytoplankton and enriched animal feed. Maturation and spawning were induced after the light?:?dark (L?:?D) cycle was increased from 8?:?16 or 12?:?12 to 24?:?0, or when the L?:?D cycle was held constant at 14?:?10. This study is one of the first studies that demonstrate initiation of maturation and spawning events of krill under controlled photoperiod. Out of three experimental batches of krill, a total of 28 spawning events were observed. The mean number of eggs per event was 1424 with a range between 139 and 3458. The mean hatching success per batch was 19.1%. The relation between photoperiod and maturity/spawning is discussed. Furthermore, hatching is compared to previous studies and the reason for the low success is discussed.     

Simultaneous biologging of heart rate and acceleration, and their relationships with energy expenditure in free-swimming sockeye salmon (Oncorhynchus nerka)

Monitoring the physiological status and behaviour of free-swimming fishes remains a challenging task, although great promise stems from techniques such as biologging and biotelemetry. Here, implanted data loggers were used to simultaneously measure heart rate (f _H), visceral temperature, and a derivation of acceleration in two groups of wild adult sockeye salmon (Oncorhynchus nerka) held at two different water speeds (slow and fast). Calibration experiments performed with individual fish in a swim tunnel respirometer generated strong relationships between acceleration, f _H, tail beat frequency and energy expenditure over a wide range of swimming velocities. The regression equations were then used to estimate the overall energy expenditure of the groups of fish held at different water speeds. As expected, fish held at faster water speeds exhibited greater f _H and acceleration, and correspondingly a higher estimated energy expenditure than fish held at slower water speeds. These estimates were consistent with gross somatic energy density of fish at death, as determined using proximate analyses of a dorsal tissue sample. Heart rate alone and in combination with acceleration, rather than acceleration alone, provided the most accurate proxies for energy expenditure in these studies. Even so, acceleration provided useful information on the behaviour of fish and may itself prove to be a valuable proxy for energy expenditure under different environmental conditions, using a different derivation of the acceleration data, and/or with further calibration experiments. These results strengthen the possibility that biologging or biotelemetry of f _H and acceleration may be usefully applied to migrating sockeye salmon to monitor physiology and behaviour, and to estimate energy use in the natural environment.