Estimating the encounter rate of Atlantic capelin (Mallotus villosus) with fish eggs, based on stomach content analysis

The number of pelagic fish eggs (cod and cunner) found in stomachs of capelin (Mallotus villosus) sampled in coastal Newfoundland was used to estimate the encounter rates between capelin and prey, and thus the effective volume swept by capelin. Fish eggs were found in 4−8% of capelin stomachs, represented an average of 1% of prey by numbers, and their abundance increased as relative stomach fullness decreased. The average number of eggs per stomach doubled for each 5-cm increase in length of capelin. The effective volume swept for eggs by capelin ranged from 0.04 to 0.84 m3/h—a rate that implies either very slow capelin swimming speeds (<1 cm/s) or that fish eggs are not strongly selected as prey. The predation rate estimated from stomach contents was higher than that predicted from laboratory studies of feeding pelagic fish and lower than that predicted by a simple foraging model. It remains uncertain whether capelin play an important regulatory role in the dynamics of early life stages of other fish.

First record of a yellowfin tuna (Thunnus albacares) from the stomach of a longnose lancetfish (Alepisaurus ferox)

In 1987 we found a juvenile yellowfin tuna, Thunnus albacares (Bonnaterre, 1788), in the stomach of a longnose lancetfish, Alepisaurus ferox Lowe, 1833. Analysis of published information on lancetfish food habits (Haedrich, 1964, 1969; Haedrich and Nielsen, 1966; Parin, 1968; Parin et al., 1969; Fourmanoir, 1969; Grandperrin and Legand, 1970; Kubota and Uyeno, 1970; Legand et al., 1972; Kubota, 1973; Fujita and Hattori, 1976; Matthews et al., 1977) led us to conclude that this was the first record of a yellowfin tuna found in a lancetfish stomach.

Dynamics of parasite population and its histopathological and histophysiological effects in the stomach of a freshwater fish

The caryophyllaeid cestode Lytocestoides fossilis infects the freshwater catfish Heteropneustes fossilis. The study was conducted for two consecutive years (2004-06) to record the bio-statistical data of the parasite. The incidence, intensity, density and index of infection of the parasite have been recorded. The infection was more during June to September, moderate during February to May and low during October to January. The parasite brought about severe histopathological changes in the stomach of infected fish. The changes observed in the stomach of fish included structural damage of the villi, inflammation, and fibrosis associated with hyperplasia and metaplasia. The hypertrophy of mucous layer led to vacuolation and necrosis. Histochemical changes were noticed with enhanced carbohydrate, protein and lipid contents. The enhanced substrate content in the infected organ might be due to the disfunctioning of the digestive tract, which results in the accumulation of various metabolites. Mucus secretion was triggered as a protective interaction against parasitic invasion. The parasitic infection affects the general metabolic state of the host and as the result, the fish becomes sluggish and moribund.

Plankton identified in stomach contents of Oreochromis niloticus (Pisces, Cichlidae) and the water system of Lakes Edward, George, and Kazinga channel - Uganda

The samples were collected from Lake Edward at Rwenshama, Kisenyi and Katwe, and from Lake George at Mahyoro, Kashaka and Kasenyi and in Kazinga Channel at Katunguru. The organisms identified from the water samples obtained irrespective of station or depth were mainly the phytoplankton (diatoms, blue-green algae and green algae). Of the phytoplankton, blue green-algae were the most abundant both in quantity and number of species especially in L. George. In order of importance were Microcystis spp, Planktolyngbya spp and Anabaenopsis spp were the dominant blue greens. Diatoms and green algae were present but less abundant. The estimated proportions of different types of phytoplankton identified in O. niloticus stomach contents indicate that bluegreen algae were the most abundant followed by the diatoms and green algae.

Preliminary studies on food and feeding habits of Polypterus endlicheri and Polypterus senegalus in Lake Chad

The food and feeding habits of Polyprerus cncllicheri and Polypterus senegalus was carried out in the months of September to October. The food of 33 Polypierus endlicheri as observed include Tilapia species (89.3%), Eutropius niloticus (28.6%), Mayfly nymph (39.3%), Dragon fly larva (56.6%) fish remains (21.4%) and detritus (7.1%). The food of27 Polypterus senegalus as observed include Tilapia sp (88.4%), Eutropius niloticus (27.9%), may fly nymph (23.3%), Dragonfly nymph (34.9%) remains (21.1%) detritus (23.3%). (9 page document) The percentage occurrence of food item found in the stomach of Polypterus endlieheri is 93.3% while that of Polyprerus senegalus is 67.4%. The dominance of Tilapia sp was establish in the study, and there is no significant difference between the feeding habit of Polypterus endlicheri and Polyprerus senegalus.

Histological atlas of Florida Surgeonfish (Acanthuridae)

This histological atlas focuses on A. coeruleus and includes major organs and tissues. Particularly note the stomach tissues of both species, which illustrate the difference in digestive strategies of the Carribbean Acanthurids. Acanthurus chirurgus was intentionally left out of this atlas, as its tissues are identical to those of ?A. bahianus(PDF has 22 pages)

Interactions between adult migratory striped bass (Morone saxatilis) and their prey during winter off the Virginia and North Carolina Atlantic coast from 1994 through 2007

The migratory population of striped bass (Morone saxatilis) (>400 mm total length[TL]) spends winter in the Atlantic Ocean off the Virginia and North Carolina coasts of the United States. Information on trophic dynamics for these large adults during winter is limited. Feeding habits and prey were described from stomach contents of 1154 striped bass ranging from 373 to 1250 mm TL, collected from trawls during winters of 1994-96, 2000, and 2002-03, and from the recreational fishery during 2005-07. Nineteen prey species were present in the diet. Overall, Atlantic menhaden (Brevoortia tyrannus) and bay anchovy (Anchoa mitchilli) dominated the diet by boimass (67.9%) and numerically (68.6%). The percent biomass of Atlantic menhaden during 1994-2003 to 87.0% during 2005-07. Demersal fish species such as Atlantic croaker (Micropogonias undulatus) and spot (Leiostomus xanthurus) represented <15% of the diet biomass, whereas alosines (Alosa spp.) were rarely observed. Invertebrates were least important, contributing <1.0% by biomass and numerically. Striped bass are capable of feeding on a wide range of prey sizes (2% to 43% of their total length). This study outlines the importance of clupeoid fishes to striped bass winter production and also shows that predation may be exerting pressure on one of their dominant prey, the Atlantic menhaden.

Report on Marine Mammal Unusual Mortality Event UMESE0501Sp: Multispecies Mass Stranding of Pilot Whales (Globicephala macrorhynchus), Minke Whale (Balaenoptera acutorostrata), and Dwarf Sperm Whales (Kogia sima) in North Carolina on 15-16 January 2005

On 15-16 January 2005, three offshore species of cetaceans (33 short-finned pilot whales, Globicephala macrorhynchus, one minke whale, Balaenoptera acutorostrata, and two dwarf sperm whales, Kogia sima) stranded alive on the beaches of North Carolina. The pilot whales stranded near Oregon Inlet, the minke whale in northern North Carolina, and the dwarf sperm whales near Cape Hatteras. Live strandings of three species in one weekend was unique in North Carolina and qualified as an Unusual Mortality Event. Gross necropsies were conducted on 16-17 January 2005 on 27 pilot whales, two dwarf sperm whales, and the minke whale. Samples were collected for clinical pathology, parasitology, gross pathology, histopathology, microbiology and serology. There was variation in the number of animals sampled for each collection type, however, due to carcasses washing off the beach or degradation in carcass condition during the course of the response. Comprehensive histologic examination was conducted on 16 pilot whales, both dwarf sperm whales, and the minke whale. Limited organ or only head tissue suites were obtained from nine pilot whales. Histologic examination of tissues began in February 2005 and concluded in December 2005 when final sampling was concluded. Neither the pilot whales nor dwarf sperm whales were emaciated although none had recently ingested prey in their stomachs. The minke whale was emaciated; it was likely a dependent calf that became separated from the female. Most serum biochemistry abnormalities appear to have resulted from the stranding and indicated deteriorating condition from being on land for an extended period. Three pilot whales had clinical evidence of pre-existing systemic inflammation, which was supported by histopathologic findings. Although gross and histologic lesions involving all organ systems were noted, consistent lesions were not observed across species. Verminous pterygoid sinusitis and healed fishery interactions were seen in pilot whales but neither of these changes were causes of debilitation or death. In three pilot whales and one dwarf sperm whale there was evidence of clinically significant disease in postcranial tissues which led to chronic debilitation. Cardiovascular disease was present in one pilot whale and one dwarf sperm whale; musculoskeletal disease and intra-abdominal granulomas were present in two pilot whales. These lesions were possible, but not definitive, causal factors in the stranding. Remaining lesions were incidental or post-stranding. The minke whale and three of five tested pilot whales had positive morbillivirus titers (≥1:8 with one at >1:256), but there was no histologic evidence of active viral infection. Parasites (nematodes, cestodes, and trematodes) were collected from 26 pilot whales and two dwarf sperm whales. Sites of collection included stomach, nasal/pterygoid, peribullar sinuses, blubber, and abdominal cavity. Parasite species, locations and loads were within normal limits for free-ranging cetaceans and were not considered causative for the stranding event. Gas emboli lesions which were considered consistent with or diagnostic of sonarassociated strandings of beaked whales or small cetaceans were not found in the whales stranded as part of UMESE0501Sp. Twenty-five heads were examined with nine specific anatomic locations of interest: extramandibular fat, intramandibular fat, auditory meatus, peribullar acoustic fat, peribullar soft tissue, peribullar sinus, pterygoid sinus, melon, and brain. The common finding in all examined heads was verminous pterygoid sinusitis. Intramandibular adipose tissue reddening, typically adjacent to the vascular plexus, was observed in some individuals and could represent localized hemorrhage resulting from vascular rete rupture, hypostatic congestion, or erythrocyte rupture during the freeze/thaw cycle. One cetacean had peracute to acute subdural hemorrhage that likely occurred from thrashing on the beach post-stranding, although its occurrence prior to stranding cannot be excluded. Information provided to NMFS by the U.S. Navy indicated routine tactical mid-frequency sonar operations from individual surface vessels over relatively short durations and small spatial scales within the area and time period investigated. No marine mammals were detected by marine mammal observers on operational vessels; standard operating procedure for surface naval vessels operating mid-frequency sonar is the use of trained visual lookouts using high-powered binoculars. Sound propagation modeling using information provided to NMFS indicated that acoustic conditions in the vicinity likely depended heavily on position of the receivers (e.g., range, bearing, depth) relative to that of the sources. Absent explicit information on the location of animals meant that it was not possible to estimate received acoustic exposures from active sonar transmissions. Nonetheless, the event was associated in time and space with naval activity using mid-frequency active sonar. It also had a number of features in common (e.g., the “atypical” distribution of strandings involving multiple offshore species, all stranding alive, and without evidence of common infectious or other disease process) with other sonar-related cetacean mass stranding events. Given that this event was the only stranding of offshore species to occur within a 2-3 day period in the region on record (i.e., a very rare event), and given the occurrence of the event simultaneously in time and space with a naval exercise using active sonar, the association between the naval sonar activity and the location and timing of the event could be a causal rather than a coincidental relationship. However, evidence supporting a definitive association is lacking, and, in particular, there are differences in operational/environmental characteristics between this event and previous events where sonar has apparently played a role in marine mammal strandings. This does not preclude behavorial avoidance of noise exposure. No harmful algal blooms were present along the Atlantic coast south of the Chesapeake Bay during the months prior to the event. Environmental conditions, including strong winds, changes in upwelling- to downwelling-favorable conditions, and gently sloping bathymetry, were consistent with conditions which have been correlated with other mass strandings. In summary, we did not find commonality in gross and histologic lesions that would indicate a single cause for this stranding event. Three pilot whales and one dwarf sperm whale had debilitating conditions identified that could have contributed to stranding, one pilot whale had a debilitating condition (subdural hemorrhage) that could have been present prior to or resulting from stranding. While the pilot and dwarf sperm whale strandings may have had a common cause, the minke whale stranding was probably just coincidental. On the basis of examination of physical evidence in the affected whales, however, we cannot definitively conclude that there was or was not a causal link between anthropogenic sonar activity or environmental conditions (or a combination of these factors) and the strandings. Overall, the cause of UMESE0501Sp in North Carolina is not and likely will not be definitively known. (PDF contains 240 pages)

The food of yellowfin and skipjack tunas in the Eastern Tropical Pacific Ocean

ENGLISH: Knowledge of the kinds of organisms eaten by tunas, and the relative importance of different kinds of organisms in different situations, is of importance to our understanding of regional and local aggregations and of the behavior of the tropical tunas. Determination of the relative importance of benthic forms in the stomachs of tunas captured in the vicinity of islands and offshore banks, compared with the forms found in the stomachs of those from oceanic areas, distant from these shoal areas, is useful to the understanding of the mechanisms by which the islands and banks attract tuna. A thorough knowledge of the diet may also reveal more about the seasonal and annual variations in the distribution of these fish along the coasts of Mexico, Central America and elsewhere. A knowledge of the diet of the tunas is basic to quantitative studies of the zooplankton and nekton in the Eastern Pacific Ocean with reference to the production of tunas. Studies of the diet of the tropical tunas by examination of stomach contents was, therefore, commenced in late 1957. SPANISH: El conocimiento de las clases de organismos de que se alimentan los atunes, y la importancia relativa de las diferentes clases de organismos en situaciones diferentes, es de valor para nuestra comprensión de las agrupaciones regionales y locales, y de los hábitos de los atunes tropicales. La determinación de la importancia relativa de las formas bénticas en los estómagos de los atunes capturados en la vecindad de las islas y de los bancos apartados de la costa, comparadas con las formas encontradas en los estómagos de los atunes procedentes de áreas oceánicas, distantes de estas áreas poco profundas, es útil para comprender el mecanismo por el cual las islas y los bancos atraen al atún. Un conocimiento completo de la dieta puede revelar también algo más acerca de las variaciones estacionales y anuales en la distribución de estos peces a lo largo de las costas de México, América Central y otras partes. El conocimiento de la dieta del atún es básico para los estudios cuantitativos del zooplancton y del necton en el Océano Pacífico Oriental, con referencia a la producción de los atunes. El estudio de la dieta de los atunes tropicales mediante el examen del contenido estomacal, fué comenzado, por lo tanto, a fines de 1957.

The food and feeding habits of the anchoveta, Cetengraulis mysticetus, in the Gulf of Panama

ENGLISH:The gill rakers of both juvenile and adult anchovetas are long and numerous, with many fine processes which make a very efficient straining apparatus. The stomach is modified into a gizzard. The intestine undergoes heteronomous growth, and attains about eight times the standard length in adults. The stomach contents of 39 samples of juvenile fish and 120 adult fish were examined. Diatoms were the principal food of all the sizes of fish examined, from 29 to 153 millimeters. Silicoflagellates, dinoflagellates, pollen grains, formaniferans, rotifer shells, crustaceans, and eggs, probably of crustaceans, were also found in small amounts. Coscinodiscus, a diatom, was the most important item found in the stomachs of the juvenile fish. No strong differences were observed in the feeding habits of different sizes of juveniles. Even taking into account their smaller size, the juveniles had smaller volumes of material and lesser numbers of organisms in their stomachs than did the adults. The stomachs of the adult fish, unlike those of the juveniles, usually contained considerable quantities of mud. Melosira, Coscinodiscus, and Thalassionema, all diatoms, were the most important organisms found in the stomachs of the adults. The incidence of Melosira was much higher in the stomachs of fish from the areas to the east of the entrance of the Panama Canal than from those to the west. No seasonal differences in the food were observed. The volume of material in the stomachs ranged from almost none to nearly 1.0 milliliter, with an average of a little more than 0.2 milliliter. Twenty-six bottom samples were examined; the organisms found corresponded very closely to those encountered in the stomachs of the adult fish. It is concluded that the juvenile anchovetas are chiefly or entirely filter feeders of the pelagic zone. The adults, however, are mostly iliophagous feeders, but possibly do some feeding upon plankton as well. SPANISH:Las branquispinas de las anchovetas, tanto en las juveniles como en las adultas, son largas y numerosas, can varias protuberancias finas que hacen de ellas un aparato filtrador muy eficiente. El estómago está modificado en una molleja. El intestino está sometido a un crecimiento heterónomo, llega a alcanzar unas oeho veces la longitud estandar en las adultas. Fué examinado el contenido estomacal de 39 ,muestras de peces juveniles y de 120 adultos. Las diatomeas fueron el alimento principal de todos los peces que fueron examinados cuyo tamaño varió entre los 29 y 153 milimetros. Se encontraron también en cantidades silicoflagelados, dinoflagelados, granos de polen, foraminíferos, conchas de rotiferos, crustáceos y huevos, probablemente de crustáceos. Coscinodiscus, una diatomea, fué el alimento más importante encontrado en los estómagos de los peces juveniles. No se observaron mayores diferencias en los hábitos de alimentación en los juveniles de diferentes tamaños. Aún tomando en cuenta su tamaño menor, los juveniles tenian volúmenes más pequeños de material y un número menor de organismos en sus estómagos que los adultos. Los estómagos de los peces adultos, diferentes a los de los juveniles, contenían por lo general considerables cantidades de fango. Melosira, Coscinodiscus, y Thalassionema, todas ellas diatomeas, fueron los organismos más importantes encontrados en los estómagos de los adultos. La contribuciónde Melosira fué mucho más alta en los estómagos de los peces procedentes de las áreas al este de la entrada del Canal de Panamá que la de aquellos provenientes del oeste. No se observaron diferencias estacionales en la alimentacion. El volúmen de material en los estómagos varió de casi cero a cerca de 1.0 mililitros, con un promedio de un poco mas de 0.2 mili1itros. Se examinaron 26 muestras de fonda; los organismos encontrados correspondieron muy cercanamente a los hallados en los estómagos de los peces adultos. Se ha llegado a la conclusión de que las anchovetas juveniles son principalmente ó enteramente filtradoras de alimentos de la zona pelágica. Las adultas, sin embargo, son en su mayoria iliófagas, pero posiblemente se alimentan también de plancton.

Sind südliche Arten in Nord- und Ostsee auf dem Vormarsch?

The long and warm summer 2003 resulted in water temperatures of about 2°C above the average. This promoted the immigration of southern species like the Anchovy, the Sardine, the Red Mullet and different Squid species. The possible conclusions of such invasions concerning the ordinary species of the area are rather contradictory: For the Western Baltic a positive correlation between the occurrence of Anchovy and a good Cod year-class is shown. For the southern North Sea, stomach investigations of Squid make a negative effect on fish eggs and larvae more likely.

Fischerei auf die wichtigsten nordostatlantischen Grundfischbestände 1998

A short review of the actual assessments on the northeast atlantic groundfish stocks of cod, saithe, haddock, redfish and Greenland halibut provided by the ICES „Arctic Fisheries Working Group“is given. All these stocks are presently considered outside safe biological limits. For the first time since 5 years the cod stock is in an endangered situation, because the assessment was to optimistic and the TAC therefore set to high. According to the recent assessments necessary changes in the commercial fishery of the year 1998 off the Nowegian coast and in the Barent-Sea area are discussed. Information on distribution and fishery of cod, haddock, saithe and redfish is given. Biological investigations were carried out onboard the German factory trawler FMS „KIEL“ in January/March and September/ Occtober 1998 in order to collect data of the German fishery in that area. Aspects of length and age distributions, and stomach- and gonad investigation are represented.

Preliminary observations on the feeding, habits and reproduction biology of Gymnarchus niloticus from Lake Chad

The preliminary results obtained from the study of stomach contents of specimens of Gymnarchus niloticus of a size ranging from 56 cm (66 grams) to 152 cm (12.0 kg.) from August to December, 1982 indicate for these sizes an exclusively piscivorous diet. The predominant prey species in Lake Chad are Tilapia/Sarotherodon , and Clarias . The prey is often cut in two parts before it is swallowed. Small prey may be swallowed whole. The implication of this prey capture method on prey-predator relationship and therefore the impact of the predator is discussed. The breeding season of Gymnarchus niloticus in Lake Chad has been deduced from observation of changes in gonad maturity stages and the results indicate that breeding takes place between August and November. Data are also presented on the fecundity, size of ripe eggs and probable size at maturity

Bacterial flora of the gut of the African snakehead, Channa obscura (Pisces: Channidae)

A qualitative and quantitative investigation of the bacterial flora of the gut of the African snakehead, Channa obscura was undertaken. The types of bacteria isolated from the different parts of the gut of C. obscura include Pseudomonas, Streptococcus, Citrobacter and Proteus. The coliform (Escherichia coli, Enterobacter) and some other Enterobacteriaceae such as Salmonella were also present. The stomach and intestine were found to have a preponderance of Pseudomonas and Vibrio species. Klebsiella sp. and Bacillus sp. (only in the pyloric caeca) were also isolated. On the whole, the correlation coefficients of the two incubation temperatures showed a high statistical significance. Thus the bacterial load of the gut of C. obscura has been shown as a function of temperature

Food composition and digestive enzymes in the gut of the African electric catfish Malapterurus electricus (Gmelin 1789) (Malapteruridae)

Analyses of stomach contents of 330 Malapterurus electricus (standard length, 10.1-30.5 cm) in Mahin Lagoon (southwestern Nigeria) established it as a bottom feeder. There was a preponderance of insects accounting for >80% occurrence and >25% of total volume in stomachs of specimens, suggesting a stenophagous predatory habit. Qualitative and quantitative assays of digestive enzymes in the different regions of the gut (oesophagus, stomach, duodenum, ileum, rectum) were investigated. Carbohydrases (amylase, maltase), chitinase, proteases (pepsin, chymotrypsin, trypsin) and lipases were detected in different gut regions with different activity. The pattern of distribution and relative activity of the enzymes correlated with the predatory diet