Movements of lumpsucker females in a northern Norwegian fjord during the spawning season

The lumpsucker Cyclopterus lumpus is distributed throughout the North Atlantic Ocean and migrates considerable distances between offshore feeding areas and shallow inshore spawning grounds. The number of the lumpsucker has declined since the mid 1980s, probably as a result of overexploitation. The lumpsucker is the preferred host of the sea louse Caligus elongates, which is a problem for marine aquaculture. However, little is known about the biology of the lumpsucker. The aims of the study were to 1) examine the movements of female lumpsucker during the spawning migration, and 2) assess the potential for lumpsucker to act as a vector for transmission of parasites and diseases between aquaculture farms and wild fish. Twenty female lumpsuckers tagged with acoustic transmitters were released during the spawning season in the inner part of Øksfjord, northern Norway and their distribution was recorded by 22 automatic acoustic receivers. The average time until departure from the fjord was 3 days, and within 1 week all fish had left the fjord. Timing of departure from the fjord was unrelated with either tidal current patterns or the time of the day. A high proportion of the fish (75%) were recorded within 200 m of fish farms, but they did not stay for extended periods at these farms. Our results suggest that mature female lumpsucker exhibit a movement pattern characterized by rapid fjord-scale migrations during the spawning season, and that they are not attracted to salmon farms in the same way as a range of other fish species.     

Specific features of distribution, some features of biology, and the dynamics of catches of smooth lumpsucker Aptocyclus ventricosus (Cyclopteridae) in waters of the Pacific Ocean off the Kuril Islands and Kamchatka

On the basis of data on bottom trawl catches in Pacific waters off the northern Kuril Islands and southeastern Kamchatka (1992–2002), quantitative indices of occurrence of the smooth lumpsucker Aptocyclus ventricosus and the range of preferred habitation temperature are provided. Its spatial and vertical distribution are analyzed, and specific features of size composition and the relationship between the length and weight of the body and between the average weight and the capture depth are considered; the diurnal, seasonal, and long-term dynamics of occurrence and of the amount of average catches is presented; data on the species composition of fish present in catches parallel to A. ventricosus are cited.     

Seasonal and interannual variation of ichthyoplankton off the coast of the Moroccan Sahara

Changes in the qualitative and quantitative composition of ichthyoplankton off the coast of the Moroccan Sahara (21–28° N) in different seasons of 1994–2007 are analyzed. In this region, the pelagic eggs and larvae of over 100 fish species belonging to 62 families have been recorded. In cold periods, off the coast of the Moroccan Sahara there is peak in the spawning of fish of the subtropical fauna. The majority of them are European pilchard Sardina pilchardus, common scad Trachurus trachurus, and Atlantic mackerel Scomber japonicus. In warm periods there is intensive spawning of fish of the tropical fauna. Among them, dominants are round sardinella Sardinella aurita, West-African scad Trachurus trecae, and Atlantic bonito Sarda sarda. The spawning biomass of principal commercial fish is calculated by the quantity of eggs laid by females. The environmental factors are indicated that influence the fluctuation of abundance and distribution of ichthyoplankton in the region under consideration.     

Biostratigraphie et Poissons fossilesde la formation de l'Argile de Boom (Oligocène moyen du Bassin Belge)

The Clay of Boom, Rupelian (R₂c of BelgianGeological Map) was sampled in five quarries of the type area (Sint-Niklaas, Steendorp, Schelle, Terhagen, Kruibeke) for otoliths and other fish remains.At the moment 65 species are known from this unit, of which 31 are represented in our samples by otoliths or teeth. The fish fauna of the Clay of Boom is essentially a marine fauna suggesting that the clay was deposited in a calm, rather deep part of the continental shelf.The Elasmobranch fauna has no biostratigraphic value, although 5 new species were identified: Pristiophorus rupeliensis, Raja casieri, Raja cecilae, Raja heinzelini and Raja terhagenesis.The Teleostean fauna is dominated by Gadidae.a typical Northern Atlantic group, and includes one species new to science «genus Gadidarum ensiformis. The dominance of Gadids reflects the progressive replacement of the Indo-Pacific fauna existing during the Eocene, by a more Atlantic one. Some of the 69 lithological subunits recognized on lithological features, are also characterized by different otolith associations and can be correlated in the different quarries sampled. Some of these (49, 41 and 35) are further more characterized by a high frequency of otoliths; therefore these can probably be localised in borings and used for correlation. The Teleostean - otoliths permit a local biozonation of the Clay of Boom. The upper part of the clay is limited below by bed 38 and characterized by the association Argentina parvula - «genus Gadidarum parvus (typical form), the middle part by «genus Gadidarum parvus (thick-set-form) and the lower part of which bed 30 forms the top is characterized by the association Raniceps tuberculosus - Trisopterus elegans. In this part of the clay otoliths are scarce.     

Parasitic castration of a vertebrate: Effect of the cymothoid isopod, Anilocra apogonae, on the five-lined cardinalfish, Cheilodipterus quinquelineatus

Parasitic castration, the specific blocking of host reproductive output by an individual parasite, is a host-parasite interaction common to many invertebrates, particularly crustaceans, echinoderms and molluscs. It can reduce host density, alter host population dynamics and the evolution of host life history traits. Here we show that parasitisation by a single female cymothoid isopod, Anilocra apogonae, castrates its vertebrate host, the five-lined cardinalfish, Cheilodipterus quinquelineatus. Parasitised male fish fail to mouthbrood their young. The gonads of parasitised fish are smaller and parasitised female fish have substantially fewer and smaller ova than do the gonads of unparasitised fish. As for parasitic castrators of invertebrate hosts, A. apogonae on C. quinquelineatus are uniformly dispersed amongst infested hosts (one adult female isopod per host), are site specific, and their body size is highly correlated with that of their host. These isopods are large relative to the body size of their hosts, averaging 3.8% of the weight of the host. Parasitised fish also weigh less and are shorter than unparasitised fish of the same age. Despite the presence of other potential hosts, A. apogonae only infests C. quinquelineatus. The consistency of the ecological correlates amongst known parasitic castrators suggests that the parasitic castrator host-parasite relationship will be recognised for other parasites of vertebrates.     

Seasonal and interannual variation of ichthyoplankton off Mauritania

Changes of the quantitative and qualitative composition of ichthyoplankton off Mauritania (21–16° N) in different seasons of 1997–2008 are analyzed. In this area, pelagic eggs and larvae of over 120 fish species belonging to 71 families are recorded. In warm periods, the fish of the tropical fauna intensively spawn off Mauritania; round sardinella Sardinella aurita, West-African horse mackerel Trachurus trecae, and jack mackerel Caranx rhonchus are dominant. In cold periods, active spawning of fish belonging to the tropical fauna is recorded, the most abundant are European pilchard Sardina pilchardus, European horse mackerel Trachurus trachurus, and Atlantic mackerel Scomber japonicus. The spawning biomass of principal commercial fish species is calculated on the basis of the quantity of eggs laid by females. Environmental factors control fluctuations of abundance and distribution of ichthyoplankton in the considered region.     

Energy transformations by the sargassum fish,Histrio histrio (L.)

Ingestion, egestion, growth, and respiration measurements were made in the laboratory on three size-classes of the Sargassum fish, Histrio histrio(L.). Comparison of three size-classes showed changes from high growth and low respiration and assimilation in small Histrio to reduced growth and increased respiration and assimilation in larger fish. A high assimilation and growth efficiency suggest that Histrio is adapted to a food-limited environment (Sargasso Sea). Energy requirements of the smallest size-class (10–29 mm) were compared to the energy provided by their dominant food source, the Sargassum shrimp Latreutes fucorum (Fabricius) and Leander tenuicornis (Say). The annual energy requirement per individual was 1.4 times greater than the food energy available. This discrepancy is attributed to the difficulty in extrapolating laboratory studies to the field and the difficulty in obtaining adequate population size measurements of the Sargassum community fauna.     

On the biology and food of small-sized fish from North and Baltic Sea areas. IV. Investigations on an eulittoral mud flat at Sylt Island

The fish fauna of an eulittoral mud flat was investigated at Sylt Island (North Sea) with special regard to its food uptake. During the course of a year the following species were caught:Pomatoschistus microps, Anguilla anguilla (elvers),Zoarces viviparus, andGasterosteus aculeatus. Considering the potentially available food, the most abundant organisms of the benthos were harpacticoids and nematodes, whereas in the phytal layer gastropods and gammarids were dominant. The benthic biomass was found to be greatest in spring, while phytal organisms were most abundant in late summer. The greatest fish density was stated in September 1974 though onlyP. microps was present. The fish biomass was highest in spring when the elvers appeared. The main food ofP. microps was epibenthos; in the diet ofA. anguilla phytal organisms dominated over epibenthos, inG. aculeatus suprabenthic organisms were also present. The most prominent food component by biomass was gammarids in all investigated fish, whereas harpacticoids were only dominant in number. During the course of the year the biomass of ingested food yielded highest values in summer and autumn, but lowest in winter. A very great predatory activity was found in September 1974, which possibly caused a grazing effect on harpacticoids. An estimation of the turnover rate of small-sized fish in this month led to a value of 70 mg dry weight m^?2 · d^?1.     

Bioaccumulation of Trace Mercury in Trophic Levels of Benthic, Benthopelagic, Pelagic Fish Species, and Sea Birds from Arvand River, Iran

In this study, concentration of mercury was determined in the trophic levels of benthic, benthopelagic, pelagic fish species, and river birds from Arvand River, located in the Khuzestan province in the lowlands of southwestern Iran at the head of the Persian Gulf. The order of mercury concentrations in tissues of the fish species was as follows: liver>gill>muscle and in tissues of the kingfisher species was as follows: feather>liver>kidney>muscle. Therefore, liver in fish and feather in kingfisher exhibited higher mercury concentration than the other tissues. There was a positive correlation between mercury concentrations in fish and kingfisher species with size of its food items. We expected to see higher mercury levels in tissues of female species because they are larger and can eat larger food items. The results of this study show that the highest mean mercury level were found in the kingfisher (Anas crecca), followed by benthic (Epinephelus diacanthus), benthopelagic (Chanos chanos), and pelagic fish (Strongylura strongylura). Mean value of mercury in fish species, S. strongylura were (0.61 μg g^?1 dry weight), C. chanos (0.45 μg g^?1 dry weight), E. diacanthus (0.87 μg g^?1 dry weight), and in kingfisher species A. crecca was (2.64 μg g^?1 dry weight). Significant correlation between mercury concentration in fish and kingfisher may be related to high variability of mercury in the fish.     

The food web in the lower part of the Seine estuary: a synthesis of existing knowledge

The Seine estuary illustrates the alterations to estuaries due to human activities heavy releases of pollutants of various origins and significant morphological changes beginning in the middle of the 19th century. The intertidal mudflat surface has been seriously reduced (< 30km²) since the channels of the Seine River came under management. While the role of the Seine estuary in the dynamics of the eastern English Channel ecosystem is recognized as important, the biological characteristics of the estuary remained relatively unknown until the 1990s. Biological diversity was progressively impoverished from the polyhaline zone to the oligohaline zone. In spite of a heavily contaminated environment, the macrobenthic and planktonic fauna of the Seine estuary remains similar to those of other northeastern Atlantic estuaries. The fauna exhibit clear contrasts between areas with very high abundance and others with very low abundance. The pelagic fauna, especially the copepod Eurytemora affinisand the shrimp Palaemon longirostris, are more abundant in the Seine estuary than in other estuaries. Diversified and abundant, Abra alba-Pectinaria koreni and Macoma balthica benthic communities occur, respectively, in the outer and inner parts of the estuary. In subtidal flats, benthic fauna is especially poor in terms of specific richness, abundance and biomass. Paradoxically, considering the high abundance of prey, fish are particularly scarce. Two food webs have been identified. In the oligohaline zone, where turbidity is maximum, the food web is exclusively planktonic, due to dredging that prevented benthic fauna from settling. In the polyhaline zone, fish populations that feed particularly on benthic fauna benefit from low turbidity and high oxygen concentrations. So, in spite of heavy organic and metallic contamination and human activities, the Seine estuary remains a highly productive ecosystem, which provides a nursery for marine fish and feeding grounds for migratory birds. A global management plan appears to be necessary in order to guarantee that the Seine estuary continues to function as it currently does.     

Global population structure of the spiny dogfish Squalus acanthias,a temperate shark with an antitropical distribution

The spiny dogfish (Squalus acanthias) is a temperate, coastal squaloid shark with an antitropical distribution in the Atlantic and Pacific oceans. The global population structure of this species is poorly understood, although individuals are known to undergo extensive migrations within coastal waters and across ocean basins. In this study, an analysis of the global population structure of the spiny dogfish was conducted using eight polymorphic nuclear microsatellite markers and a 566‐bp fragment of the mitochondrial ND2 gene region. A low level of genetic divergence was found among collections from the Atlantic and South Pacific basins, whereas a high level of genetic divergence was found among Pacific Ocean collections. Two genetically distinct groups were recovered by both marker classes: one exclusive to North Pacific collections, and one including collections from the South Pacific and Atlantic locations. The strong genetic break across the equatorial Pacific coincides with major regional differences in the life‐history characters of spiny dogfish, suggesting that spiny dogfish in areas on either side of the Pacific equator have been evolving independently for a considerable time. Phylogeographic analyses indicate that spiny dogfish populations had a Pacific origin, and that the North Atlantic was colonized as a result of a recent range expansion from the South American coast. Finally, the available data strongly argue for the taxonomic separation of the North Pacific spiny dogfish from S. acanthias and a re‐evaluation of the specific status of S. acanthias is warranted.     

Condition and size of the non‐native pikeperch Sander lucioperca (Linnaeus, 1758) in Portuguese river basins

We studied life‐history traits focusing on the growth and condition of the pikeperch Sander lucioperca to evaluate its phenotypic plasticity when introduced to new environments. Pikeperch is a non‐native fish introduced to Iberian freshwater fauna in 1998 that quickly spread to other river basins through human‐mediated activities, occupying now a wide variety of habitats along mainland Portugal. Condition (K and SMI), fork length at age, and length–weight relationships were studied for Portuguese populations. Pikeperch fork length for ages 1, 2, 3, and 4 was different between several populations. We applied generalized linear models (GLM) to study the influence of habitat type, latitude, altitude, time after first detection, and fish prey richness on pikeperch populations size at age 4 and condition. We observed higher condition values on populations from lower altitudes at lentic systems more recently introduced. But higher fork length at age 4 was found in populations from higher altitudes, on older populations with higher prey richness. Habitat type, time since first detection, and fish fauna composition are discussed as the main environmental factors explaining the observed phenotypic plasticity with concerns on predatory impact on native fauna.     

Presence of the telescope fish Mendosoma lineatum in Patagonian waters,a new species in the ichthyological fauna from the south‐west Atlantic Ocean

The presence of the telescope fish Mendosoma lineatum in Patagonian waters of Argentina is reported. Mendosoma lineatum is the second species of the Latridae recorded in the south‐west Atlantic Ocean and its presence in Patagonia is an addition to both the ichthyological fauna of the Argentinean Sea and the south‐west Atlantic Ocean.     

Biodiversity of <Emphasis Type="Italic">Spongosorites coralliophaga</Emphasis> (Stephens, 1915) on coral rubble at two contrasting cold-water coral reef settings

Cold-water coral reefs (CWRs) in the northeast Atlantic harbor diverse sponge communities. Knowledge of deep-sea sponge ecology is limited and this leaves us with a fragmented understanding of the ecological roles that sponges play in CWR ecosystems. We present the first study of faunal biodiversity associated with the massive demosponge Spongosorites coralliophaga (Stephens, 1915) that typically colonizes coral debris fields of CWRs. Our study focused on the sessile fauna inhabiting sponges mixed with coral rubble at two contrasting settings in the northeast Atlantic: the shallow inshore (120–190 m water depth) Mingulay Reef Complex (MRC) and the deep offshore (500–1200 m) Logachev Mound (LM) coral province. MRC is dominated by the scleractinian Lophelia pertusa, while LM is dominated by L. pertusa and Madrepora oculata. Nine sponge–coral rubble associations were collected from MRC and four from LM. Measurements of abundance, species richness, diversity, evenness, dry biomass, and composition of sessile fauna on sponge and coral rubble microhabitats were undertaken. Differences in community composition between the two regions were mainly a response to changes in fauna with depth. Fauna composition was also different between sponge and coral rubble within each region. Infauna constituted a minor component of the sponge-associated fauna in MRC but had a higher contribution in LM. Sponge and coral rubble sessile fauna in both regions was mainly composed of cnidarians and molluscs, similarly to some previous studies. Sponges’ outer surfaces at MRC were colonized by a species-rich community with high abundance and biomass suggesting that S. coralliophaga at MRC acts as a settlement surface for various organisms but such a role is not the case at LM. This difference in the role of S. coralliophaga as a biological structure is probably related to differences in fauna composition with depth, bottom current speed, and the quantity/quality of food supplied to the benthos.     

The feeding habits of Sargochromis Codringtonii in Lake Kariba, Zimbabwe

The food of adult Sargochromis codringtonii in Lake Kariba was dominated by prosobranch snails with pulmonate snails forming an insignificant dietary component. S. codringtonii does not show particular preference for any snail species, feeding on those species that are readily available. Morphometrical analysis of the feeding structures of S. codringtonii showed that the fish is well adapted to handling a molluscivorous diet. The pharyngeal jaws with their flat crowned teeth are well adapted to crushing molluscs. The daily food consumption rate of S. codringtonii was estimated over different seasons. Estimates of food consumption indicate that the fish consumed 13.96% of their dry body weight per day in summer falling to 4.46% in winter. The low consumption of pulmonate snails suggests that S. codringtonii can not be a successful biological control agent against the vectors of schistosomiasis.     

Focus: Zoonotic Disease: Biology,Epidemiology, Clinical Features,Diagnosis, and Treatment of Selected Fish-borne Parasitic Zoonoses

Fish-borne parasites have been part of the global landscape of food-borne zoonotic diseases for many decades and are often endemic in certain regions of the world. The past 20 years or so have seen the expansion of the range of fish-borne parasitic zoonoses to new geographic regions leading to a substantial public health burden. In this article, we summarize current knowledge about the biology, epidemiology, clinical characteristics, diagnosis, treatment and control of selected fish-borne helminthic diseases caused by parasitic roundworm (Anisakis), tapeworm (Dibothriocephalus), and fluke (Metagonimus). Humans acquire infection via consumption of raw or improperly cooked fish or fish products. The burden from these diseases is caused by morbidity rather than mortality. Infected patients may present with mild to severe gastrointestinal (eg, abdominal pain, diarrhea, and indigestion) or allergic manifestations. Patients are often admitted to the hospital or clinic with acute symptoms and no prior health problems and no travel history. Diagnosis is often established based on the detection of the diagnostic parasite stages (eg, eggs or tapeworm segments) in the patient’s feces. Sometimes imaging is required to exclude other causes and avoid unnecessary surgery. Dibothriocephalus and Metagonimus are mainly treated with praziquantel. Extraction of adult Dibothriocephalus or Anisakis larvae from the bowel ensures complete elimination of the parasites and prevents a relapse of infection. The development and implementation of more efficient food safety and public health strategies to reduce the burden of zoonotic diseases attributable to fish-borne parasites is highly desirable.     

The elemental composition of swimbladders in some deepwater fishes of the North Atlantic

The first data on the elemental contents of the swimbladder wall of three deepwater fish species from the North Atlantic (the snubnosed spiny eel Notacanthus chemnitzii, the Kaup’s arrowtooth eel Synaphobranchus kaupii, and the roughhead grenadier Macrourus berglax) are presented. It is supposed that survival of specimens of the first two species upon their ascent from great depths that subject them to sharp changes of pressure is connected with the properties of the durable and flexible swimbladder walls with increased contents of some metals (aluminum, copper, iron, mercury, potassium, manganese, chromium, and cadmium). Adaptation to sharp changes of pressure in N. chemnitzii and S. kaupii probably develops during ontogeny, during the transition from habitation in the epipelagic zone during the larval stage to the deepwater habitat of the adult fish.     

Feeding of pelagic fish in waters of Mauritania: 3.—Atlantic Chub mackerel <Emphasis Type="Italic">Scomber colias</Emphasis>, Atlantic horse mackerel <Emphasis Type="Italic">Trachurus trachurus</Emphasis>, Cunene horse mackerel <Emphasis Type="Italic">Trachurus trecae</Emphasis>

Feeding peculiarities of mass pelagic everyphagous fish Atlantic Chub mackerel Scomber colias, Atlantic horse mackerel Trachurus trachurus, Cunene horse mackerel Trachurus trecae from the Canary upwelling and the frontal zones of Mauritania were investigated. Atlantic Chub mackerel feeds mainly on fish inhabiting the zone of epipelagial, crustaceans and other organisms distributing in the sound scattering layers and also detritus and detritus–algal mixture. Cunene horse mackerel and Atlantic horse mackerel feed on mesopelagic fish and the organisms from the sound scattering layers. Feeding competition between these species does not occur due to non-concurrence of the places for concentration and nourishment. Correlation of food components, their occurrence and nourishment change for all species in conformity with fish sizes, physiological conditions and the season.     

Effects of Body Size and Food Ration on Over-winter Survival and Growth of Age-0 Atlantic cod, Gadus morhua

This study examined the effects of body size and food ration on over-winter survival of age-0 Atlantic cod. Cod were divided into two groups based on standard length (large=76.95±1.10 mm SL; small=57.65±1.02 mm SL; mean±1 SE) and wet weight (large=4.02± 0.21 g; small=1.52±0.09 g). Replicate tanks (n=2) of 10 large and 10 small cod were exposed to one of two food rations (0.25% and 1.0% body weight day^-1) for the entire experiment (December to June). Tanks were examined daily for mortalities and feeding was adjusted accordingly. The experiment was run under ambient light and seawater conditions. All but large age-0 cod exposed to the low food ration grew over the course of the experiment. The specific growth rate (SGR) of small cod was significantly higher (0.2425% wet weight day^-1) than that of the large fish (0.0443% wet weight day^-1). Food ration had no significant influence on SGR or over-winter survival. Significantly more of the large age-0 cod survived the winter (58.5% of those originally introduced) compared to the smaller fish (14%). Our results are consistent with those from studies of several other fish species, and are discussed in relation to the ecology of age-0 cod, and their potential use in aquaculture in Newfoundland.