Foraging in yellow perch,Perca flavescens: biological and physical factors affecting diel periodicity in feeding,consumption, and movement

Synopsis We examined the diel chronology in food consumption and dietary composition, and in the local distribution of yellow perch,Perca flavescens, at 3 h intervals over two 24 h periods during the summer at Baptiste Lake, Alberta. Feeding intensity, as indicated by changes in stomach fullness, increased throughout the day, peaked in late evening, and almost ceased after sunset. Changes in perch densities at the sampling site reflected the pattern of feeding intensity, indicating that movements into the littoral zone are correlated with foraging. Perch diet composition, analyzed as percent occurrence, relative numerical abundance, and percent contribution by weight, differed significantly between times of day, particularly between day and night, and between sampling periods. These differences could be related both to prey behavior and distribution, and to changes in perch foraging behavior in response to light intensity. In terms of biomass, forage fish, amphipods, chironomids, and trichoptera were the most important food items on both sampling dates.     

Feeding ecology and life history variation of the blue tit in Mediterranean deciduous and sclerophyllous habitats

Summary High variation in laying date and clutch size of the blue tit between a Mediterranean mixed habitat on the mainland, southern France, and a sclerophyllous habitat on the island of Corsica is hypothesized to be related to differences in the food supply. The diet of the nestlings and feeding frequencies were studied using camera nestboxes and electronic chronographs. Food items brought to the nestlings were much more diverse on Corsica than on the mainland, including many fewer caterpillars and a wider range of taxa. However, when expressed as a volume index, prey items were on average larger on Corsica than on the mainland. Feeding frequencies were significantly lower on Corsica. A good correlation was found in both habitats between laying date and the caterpillar peak date, although both the leafing development of oaks and the peak of abundance of caterpillars occurred 3 weeks later in the Corsican sclerophyllous trees than in the mainland deciduous ones. Differences in the feeding ecology of tits between the two habitats are discussed in the light of the evergreen habit, which means that only 30% of leaves are available for phyllophagous insects instead of 100% in deciduous trees. the combination of a late and low food supply in evergreen trees is the best explanation for the differences in breeding traits betwen the two populations.     

Seasonal aspects of daily ration and diet of largemouth bass,Micropterus salmoides,with an evaluation of gastric evacuation rates

Synopsis Sample of stomach contents collected on 10 dates from May to October, 1978, were used to describe the diet and estimate the daily ration of subadult largemouth bass (primarily age-III fish) in Lake Rebecca, Minnesota. The method of Elliott & Persson (1978) was used to estimate daily ration. Data from sources in the literature were used to quantify gastric evacuation, which was found to be adequately described by an exponential decay model. The exponent of gastric evacuation increased exponentially with temperature. Seasonal changes in the diet with respect to composition, distribution of food among stomachs, and food particle size were reflected in the seasonal pattern of growth. Weight gain and the formation of scale annuli did not occur until the diet shifted from large bluegills and insects to age-0 largemouth bass and bluegills. Estimates of daily ration ranged from almost zero in mid-May and early June to over 5% in late August. The use of median weights of stomach contents was found to yield more meaningful estimates of the daily ration of individual bass than those based on means. Estimates based on medians were consistent with the observed pattern of growth and with information on maintenance rations and satiation levels. A growth-limiting lack of suitably-sized forage fish apparently occurred in the early part of the growing season.Paper Number 11,657, Scientific Journal Series, Minnesota Agricultural Experiment Station, St. Paul, MN. 55108.     

Ontogenetic diet shift, feeding rhythm, and daily ration of juvenile yellowfin goby Acanthogobius flavimanus on a tidal mudflat in the Tama River estuary, central Japan

To ascertain the feeding habits of benthic juvenile yellowfin goby Acanthogobius flavimanus, the gut contents of 599 specimens (15–41 mm in standard length, SL), collected on a tidal mudflat in the Tama River estuary throughout the diel cycle, were examined. The major prey items changed from harpacticoid copepods to errant and sedentary polychaetes at ca. 20 mm SL. Prey width increased with fish size. Fish of 26–28 mm SL fed mainly from sunset to morning, with highest feeding intensity during twilight hours and/or high tide. Based on the gut evacuation rate estimated from a forced feeding experiment in the laboratory and data for the diel change of mean gut-content volume in the field, the daily ration of juvenile yellowfin goby (26–28 mm SL) was calculated to be 13.8 mm³ fish⁻¹ day⁻¹. This volume is approximately equivalent to 3.9 individuals of the errant polychaete Ceratonereis erythraeensis (9.7 mm in body length, BL) or 8.1 individuals of the sedentary polychaete Prionospio japonica (14.8 mm BL), both species occurring abundantly on the mudflat during the study.     

Reproduction and feeding of the mountain mullet,Agonostomus monticola,in Trinidad,West Indies

Synopsis Reproduction and feeding were studied in mountain mullet,Agonostomus monticola, in northeast Trinidad during the period January 1987 to September 1988. Macroscopic and microscopic examination of the gonads indicated a single, distinct reproductive season from June to October during the wet season. Evidence implies only one spawning event per individual during the reproductive season. Females significantly outnumbered males resulting in a sex ratio of 20.4:1. The mean size at maturity for females was 135 mm fork length (FL). Fecundity (F) is related to size by the equations F = 167.3 FL^2.7 and F = 16430.7 G + 235079 (G = gutted weight).A. monticola was found to be an omnivorous feeder. The dominant food groups found in the stomachs were insects, prawns, fruits and algae, in order of decreasing importance.     

Feeding dynamics,nitrogen budgets,and ecosystem role of a desert stream omnivore,Agosia chrysogaster (Pisces: Cyprinidae)

Synopsis Feeding habits, diel periodicity and total daily ingestion, and nitrogen budgets of longfin dace (Agosia chrysogaster) were examined on two occasions when food quality, but not quantity, differed. Agosia chrysogaster was found to be an opportunistic omnivore, consuming primarily insects when the preferred taxon (baetid mayflies) was abundant in the environment, but consuming primarily algae when mayfly abundance was low. Ingestion provided a better measure of diel feeding periodicity than gut fullness; feeding was diurnal on both sample dates, but more markedly so when the primary food was algae. Mean nitrogen content of algal foods was low, and A. chrysogaster apparently compensated for this by increasing its daily ingestion rate when algae were the major food. A reduction in nitrogen content of food during digestion from 4–6% (of dry mass) to less than 1% (in feces) suggested a high assimilation efficiency for nitrogen (nitrogen assimilated/nitrogen consumed = 72–78%). Populations of this abundant and successful cyprinid in Sonoran Desert streams may play an important role in ecosystem nitrogen dynamics. Nitrogen stored in fish biomass comprised 3–6% of the total nitrogen stored in Sycamore Creek, and excretion of ammonia by the fish represented 5–10% of total nitrogen uptake by algae. Such rapid recycling of usable nitrogen to primary producers is significant in this nitrogen limited stream ecosystem.     

Selective ingestion of detritus by a north temperate omnivorous fish, the juvenile white sucker, Catostomus commersoni

Synopsis The capacity of the juvenile white sucker, Catostomus commersoni, to feed selectively on detritus was examined by analyzing gut contents of fish feeding in a northern Michigan pond and in laboratory aquaria. Suckers selected fine particle detritus. The median length of detritus particles consumed by pond suckers ranged from 26–38 m for all seasons sampled. Although suckers in the pond ingested invertebrates > 215 m they never ingested detritus particles > 215 m. Suckers fed pond detritus in laboratory aquaria selectively ingested the fine particle fraction (Kolmogorov-Smirnov test, p < 0.0001). Suckers excluded particles > 220 m and ingested a median particle size of 54 m. Amorphous detritus particles comprised 100% of the detritus particles in 93% of the foreguts analyzed. Suckers fed fine particle (< 45 ) pond detritus in laboratory aquaria rejected the inorganic fraction and selectively ingested organicmaterial with the highest protein and energy content. Ash free dry mass (AFDM) as a percent of dry-mass was 2.6 times greater in the foregut contents than in the detritus (p < 0.001). The amino acid concentration and energy density of the ingested organic matter were 1.9 times higher (p < 0.044) and 1.3 times higher (p < 0.025) than the respective amino acid and energy content of the organic fraction of the detritus. These results indicate that suckers have the capacity to consume selectively fine particle detritus with the highest nutritional value.     

Food passage time and daily ration of bighead carp,Aristichthys nobilis,kept in cages

Synopsis The food passage time of bighead carp weighing 13 to 2850 g was 7.1 to 12.8 h and the daily food ration was 5.7 to 2% of body weight at water temperatures ranging from 21 to 28.5°C. Food passage time tended to be shorter for larger fish because the speed of passage was substantially higher for the larger fish: 323 mm h^–1 for the larger fish and 67 mm h^–1 for smaller fish. Gut length increased with increased body length. Relative gut length showed great variability. It increased with increasing fish body length up to about 250 mm and remained similar for larger fish.     

Food consumption of yellowfin tuna,Thunnus albacares, in Sri Lankan waters

Synopsis A total of 4181 stomachs of yellowfin tuna,Thunnus albacares (22–164 cm FL), mainly caught by gillnets in the period from July 1984 to June 1986 were analyzed. Food consumption of yellowfin tuna in nature was determined using the values of the average stomach content, incorporating laboratory measurements of gastric evacuation rates in a feeding model. The diet of yellowfin tuna around Sri Lanka comprised a variety of macro zooplanktonic and nektonic organisms. Juveniles < 39 cm FL, are planktivores. Tuna > 40 cm FL gradually increase their consumption of fishes with increasing size. Among fish speciesAuxis sp. are the most important. The daily food consumption of juvenile yellowfin tuna (22–59 cm FL) range from 1.8 g to 136.2 g, increasing to about 284.7 g to 551.9 g for the medium size tuna (60–99 cm FL). The adult tuna (100–>130 em FL) consume around 513 g to 538.8 g of prey per day. Daily ration estimates increase from 2.1% to 5.5% of body weight with increasing size up to 70 cm FL, beyond which it decreases. The predatory pressure of yellowfin tuna on commercially important fishes and other species is discussed.     

Specializations and limitations in the utilization of food resources by the carp,Cyprinus carpio: a study of oral food processing

Synopsis The wide variety of aquatic food is considered to be instrumental for the diversification in fish species. Yet their abilities and inabilities of handling food are poorly known. For these reasons the food processing and feeding repertoire of the adult carp, Cyprinus carpio, fed on a variety of food types, were analyzed by light and X-ray cinematography of the head parts and by electromyography of the head and body muscles during feeding. Nine stereotyped movement patterns (particulate intake, gulping, rinsing, spitting, selective retention of food, transport, crushing, grinding and deglutition) compose the feeding process, their sequence and frequency were adjusted to the type of food. Following quantitative morphological analysis at macroscopic, light- and electronmicroscopical level, the relations between the functioning and architecture of the feeding apparatus were established. The structure and dimensions of the mouth opening, the protrusible upper jaw, the slit-shaped pharyngeal cavity, the palatal and postlingual organ, the branchial sieve, the pharyngeal masticatory apparatus and the distribution of taste buds, mucous cells and muscle fibers along the oropharyngeal surface were the directive structural characters used for estimating the abilities in food processing. The specializations for utilizing food items and its limitations, derived from structural and functional data, are compared with diet data found in the literature in order to evaluate the relative position of the carp in competition for food in the aquatic environment. It is established that the ‘omnivorous’ carp is specialized in effective handling of several categories of aquatic food, even when these are mixed with non-food (bottom invertebrates <4% SL in diameter) since the palatal organ enables the carp to separate food from non-food. This includes very hard-skinned food items, processed with the powerful pharyngeal jaws of the fish, and to a lesser extent zooplankton (>250 μm). The carp is at the same time very limited in processing long and struggling prey (e.g. fish) as well as vegetable matter, due to the lack of oral teeth and the specialized morphology of its pharyngeal chewing apparatus. These feeding abilities agree with diet data from literature. The reported herbivorism of carp illustrates its opportunism in feeding behaviour. Specialization in feeding is discussed and the necessity to take into account the total series of post-capture feeding actions for a more complete view on trophic specialization. Food intake and the intra-oral food processing of carp are bound to the structures of its sensory, central processing and effector apparatus and to the plasticity in their functioning. These together determine its feeding efficiency in exploiting the available aquatic food resources. Next to ethological and ecological studies functional morphology is another important tool to explain the trophic interactions of fish.     

Feeding ecology of mandrills (Mandrillus sphinx) in campo animal reserve,Cameroon

A field study on the ecology of mandrills (Mandrillus sphinx) was carried out for 28 months in Cameroon. Fresh food remnants and large quantities of fresh feces were collected by following the groups. Analyses of these products indicated that fruit (including seeds), monocotyledonous plant leaves and insects (especially ants and termites), were frequently eaten. Mandrills mostly ate the plant and animal foods in the lower forest stratum and on the ground. Fallen seeds and monocotyledonous plant leaves were eaten more frequently in the minor fruiting season than in the major fruiting season presumably to compensate for the shortage of fresh fruit during the former. Daily travel distances were shorter during the minor fruiting season than during the major fruiting season, because in the minor fruiting season mandrills forage for small food items, such as the new leaves and piths of monocotyledons and fallen seeds which are sparsely distributed on the ground, while in the major fruiting season they search for widely distributed food such as fruit. The daily pattern of group movement and a food intake experiment suggest that mandrills move and feed continuously throughout the day. Use of fallen seeds and monocotyledonous plant leaves appears to enable mandrills to maintain a terrestrial life in the tropical rain forest. The feeding and ranging characteristics of mandrills are basically similar to those of other baboon species in open land, though their environments differ extremely.     

根据野外调查资料评估鱼类的日摄食量

基于海洋渔业资源常规调查和河口定置网取样资料 ,将调查期间同一鱼种各取样时刻的消化道 (或胃 )内含物量视为发生在 2 4小时内的同一样本空间的不同事件 ,根据消化道内含物的变动确定鱼类的不摄食时段以计算排空率。为定量早期幼鱼及消化系统复杂的鱼类消化道内含物重量 ,建立了空消化道重 (EDW ) -体长(BL) -体重 (BW )经验关系式 ,即EDW =α BWBLβ δ。应用Eggers模型或Elliott Persson模型对日摄食量进行评估。研究获得以下鱼类的日摄食量 (约占体重百分比 ) :渤海大面调查所获幼鱼 ,蓝点马鲛 (Scomberomorusniphonius,16 0 1± 1 96cm ,3 0 95± 12 3 2 g ,n =159) 13 5%、黄鲫 (Setipinnataty ,7 2 6± 1 99cm ,2 89±4 0 8g ,n =2 3 9) 15%、小黄鱼 (Pseudosciaenapolyactis ,6 84± 1 41cm ,6 94± 4 0 7g ,n =2 72 ) 13 5% ,斑(Konosiruspunctatus ,9 49± 0 91cm ,10 0 8± 3 2 8g ,n =10 7) 110 % ;河口定置网所获早期幼鱼 ,斑 (1 77± 0 2 1cm ,0 0 4± 0 0 2g ,n =50 5) 40 % ,黄鳍刺虎鱼 (Acanthogobiusflavimanus ,1 82± 0 16cm ,0 0 6±0 0 1g ,n =93 0 ) 15%     

Diel feeding periodicity, daily ration and vertical migration of juvenile Cape hake off the west coast of South Africa

Feeding periodicity, daily ration and vertical migration of juvenile Cape hake Merluccius capensis are investigated from midwater and bottom trawl collections taken during a 42-h period between 29 February and 2 March 1992 at a fixed position off the west coast of South Africa. Feeding of 10-20 cm hake intensified during the night when they ascended into subsurface layers to prey on recruits of anchovy Engraulis capensis. Larger hake remained close to the bottom, were partially cannibalistic and exhibited no diel feeding periodicity. M. capensis appear to migrate vertically and feed asynchronously in midwater, as individuals, and not as a population, returning to the bottom when satiated. Based upon the exponential rate of decline in stomach fullness throughout the day, the evacuation rate by hake <20 cm was estimated as 0.054 h⁻¹; 90% evacuation of anchovy prey required an estimated 43 h. Using the Elliott & Persson and Eggers methods, the daily ration was estimated as 5.51 and 4.15% of wet body weight respectively. The effect of the foraging behaviour of M. capensis on the appropriateness of acoustic sampling for estimates of their abundance is discussed.     

Relationship between shape and trophic ecology of selected species of Sparids of the Caprolace coastal lagoon (Central Tyrrhenian sea)

Synopsis The shapes of juveniles of nine species of the family Sparidae (Diplodus annularis, Diplodus puntazzo, Diplodus sargus, Diplodus vulgaris, Lithognathus mormyrus, Pagellus acarne, Sarpa salpa, Sparus aurata, Spondyliosoma cantharus), collected in the tide channel of the Caprolace Lagoon (Central Tyrrhenian Sea—Italy) were studied using geometric morphometry. These species have different ecologies. The trophic ecology of each species, reported as TROPH values, are related to shape. For the first time the relationship between shape and trophic ecology in sparids was studied in a quantitative way giving an ecomorphological meaning to the shape differences. Mean shapes of carnivorous, omnivorous and herbivorous fish were extracted, analyzed and found to be unique. Strict herbivores such as Sarpa salpa have a small mouth gap; omnivores such as the four species of the genus Diplodus have a higher body (discoidal) and a caudal peduncle shorter and higher; carnivorous species such as Lithognathus mormyrus, possess a relatively larger head region, a larger mouth gap, a longer body and a caudal peduncle longer and narrower.     

Aspects of the foraging behaviour of the Antarctic Tern Sterna vittata gaini at Harmony Point, South Shetland Islands

During January and February of 2002 and 2003, we studied the diet of the Antarctic Tern Sterna vittata gaini at two colonies in Nelson Island, South Shetland Islands, by identifying the prey fed to chicks by breeders. The fish Notothenia coriiceps was the main prey in both seasons, followed by the myctophid Electrona antarctica, Antarctic krill Euphausia superba and gammarid amphipods. The contribution of fish to the diet increased as chicks grew older. Fish and amphipods were brought to chicks during the day, whereas adults brought Antarctic krill at sunrise and sunset. Both the duration of the feeding trips and the number of trips per foraging bout varied according to the type of prey caught. Preliminary information suggests that, among other causes, the foraging strategy is strongly influenced by the predation pressure of skuas on chicks. Results are compared with the only two previous study on the diet of the Antarctic Tern at the South Shetland Islands.     

Feeding behavior of leaf-like juveniles of the round batfish <Emphasis Type="Italic">Platax orbicularis</Emphasis> (Ephippidae) on reefs of Kuchierabu-jima Island,southern Japan

Feeding behavior of juvenile batfish Platax orbicularis, which presents a mimic state resembling a fallen leaf drifting on the water surface, were surveyed on reefs off Kuchierabu-jima Island, southern Japan. The fish consistently showed drifting swimming patterns on the surface during daylight hours, and fed in a picking–feeding manner on algae covering floating materials or substrates near the water surface. The fish drastically switched to planktivory during the night as they actively hunted free zooplanktonic particles through combined ram and suction feeding manners. Stomach content analysis supported that the fish adopted different feeding tactics, targeting different food items between the two diel periods. Even without an abrupt change of habitat use, due to its mimic state, juveniles of P. orbicularis explore different preys according to their daily activities.     

The feeding ecology of the pit-making ant lion larva,Myrmeleon bore: Feeding rate and species composition of prey in a habitat

The prey species composition and feeding rate of the pit-making ant lion larva,Myrmeleon bore Tjeder, which inhabits open sandy areas, were examined. Not less than 30 prey species, most of which were ants, were collected during a research period of 1.5 years. First instar larvae most often (81.1%) captured ants. Although 3rd instar larvae captured larger-sized prey than individuals of any other instar, they also captured small prey. The feeding rate of 3rd instar larvae was estimated by using the frequency of observed predation (FOP; (no. of ant lions handling a prey)/(total no. of pits observed)), the prey-handling time and the rhythm of daily foraging activity. FOP ofM. bore larvae was constant on the whole from spring to autumn. It was estimated that each captured 1.25 prey per day on average during this period. This estimate, however, was the feeding rate for days on which there was no rain. Assuming that the larvae cannot capture prey due to pit destruction when there is more than 10 mm of rainfall per day, the figure was reduced to 1.03 prey/day. The estimated feeding rate was evaluated with reference to larval foraging behavior.     

Feeding ecology and daily food consumption of common sole, Solea vulgaris Quensel, juveniles on the French Atlantic coast

This study describes feeding rhythms in juvenile sole (0- and I-groups) and differences in choice of prey according to age and feeding time. In the same biotype, 0-group fish select amphipods or young opisthobranchs, whereas I-group fish eat chiefly polychaetes such as Pectinaria koreni . The daily food consumption for juvenile soles in the field (T = 19.8°C) is estimated at 7% body dry weight in 0-group and probably less in I-group. When compared with estimates from previous methods or models, these rations are intermediate between estimates from Kuipers' method, with a gastric evacuation rate ( R ) per hour representing three times the amount of food in the stomach, and those from Elliott & Persson's model with R value around 1.46.     

Feeding ecology of two planktonic sculpins, Comephorus baicalensis and Comephorus dybowskii (Comephoridae), in Lake Baikal

Planktonic sculpins (Comephorus baicalensis and Comephorus dybowskii) are endemic to Lake Baikal, and their migration behavior is characterized by their strange movements, which occur only vertically. We investigated their detailed food sources at each growth stage by stable isotope analyses in combination with stomach content analysis. At all growth stages, both fishes and amphipods were the main diet for C. baicalensis, whereas amphipods alone were the main diet for C. dybowskii. Our results indicate that the relationship between the two species shifts from a competitive interaction to a predator–prey interaction with the growth stages of C. baicalensis.     

Food habits and ontogenetic changes in the diet of the sandbar shark, Carcharhinus plumbeus, in Hawaii

The sandbar shark, Carcharhinus plumbeus, is a wide-ranging coastal species in tropical and temperate regions, and it is the most common species of shark in Hawaii, as in many locations where it occurs. Information on the diet and feeding habits of this species in the Pacific Ocean are extremely limited. For this study we quantified the diet of sandbar sharks in Hawaii based on records collected during the Hawaii Cooperative Shark Research and Control Program from 1967 to 1969. During this program a total of 565 stomachs were examined, of which 265 contained food. Sharks ranged in size from 59 to 190 cm total length. Teleosts were the most common prey group, but both cephalopods and crustaceans also occurred frequently. Ontogenetic changes in diet of sandbar sharks were apparent, with crustaceans forming a greater proportion of the diet of smaller sharks. Both cephalopods and elasmobranchs increased in importance with increasing shark size. Prey diversity also increased with size, with large, mobile, and reef prey species found more commonly in the diet of larger sharks. Mature male and female sharks appeared to segregate by depth, though major differences in the diet between the sexes were not apparent. However, there was some evidence of dietary differences between sharks caught in different depths and seasons. The results of this study suggest that sandbar sharks in Hawaii and throughout the world, are primarily piscivores, but also consume a variety of invertebrate prey, and that their diet varies with geographical location and stage of development.