Inheritance of allozymes in Atlantic herring (Clupea harengus harengus)

Progeny from single pair crosses of Atlantic herring were examined to determine the heritability of genetic variation at seven polymorphic allozyme loci. Mendelian inheritance of codominant autosomal alleles was established for IDH-2, LDH-1, LDH-2, ME-2, PGM-1, and PGI-2. This demonstration of Mendelian inheritance is essential for accurate interpretation of allozymic variation among natural populations of this pelagic species.     

Life cycle of Hysterothylacium haze (Nematoda: Anisakidae: Raphidascaridinae)

Natural infections with Hysterothylacium haze in the Japanese common goby, Acanthogobius flavimanus, were observed in detail. In gobies in which no worm eggs were deposited, second-stage larvae were found in the digestive tract wall, and third-stage larvae occurred in the digestive tract wall, mesentery, and body cavity, whereas fourth-stage larvae and adults were found in the body cavity. This stage-habitat relationship demonstrates the infectivity of second-stage larvae to the goby and the larval migration. In heavily infected gobies, eggs and all worm stages, from hatched second-stage larvae to adults, often were found together in the body cavity of one individual host, suggesting that hatched second-stage larvae can develop in the body cavity. It was shown experimentally that H. haze develops to the second stage in the egg and does not hatch spontaneously. When a goby was fed the viscera of heavily infected gobies containing eggs and various stages of worms or artificially incubated eggs containing second-stage larvae, second- and third-stage larvae were recovered from the digestive tract wall, and fourth-stage larvae and adults were found in the body cavity. When polychaetes or crustaceans were placed in contact with infected goby viscera or incubated eggs, only second-stage larvae were recovered from the body cavity of the invertebrates. The experimental results were consistent with observations on natural infections and indicate that the direct life cycle of H. haze may involve invertebrates as transport hosts.     

Length changes in herring (Clupea harengus) larvae: effects of capture and storage in formaldehyde and alcohol

The effects on standard length of storing laboratory-rearedlarval herring (9–19 mm live length) in 4% buffered formaldehydeor 70% buffered ethanol with and without simulated capture bytowed net were assessed. Lengths during storage were consideredstable after 15 days for larvae placed directly in formaldehyde,and after 30 days for larvae placed directly into alcohol orfor larvae treated by net-capture simulation before storage.The following linear regressions described the relationshipsbetween live length and the stored lengths of larvae after thesetimes: for larvae stored directly in formaldehyde, L = 1.765+ 0.867 x X₁ for larvae stored directly in alcohol, L = 0.564+ 0.971 x X₁; for larvae subjected to net-capture simulationthen stored in formaldehyde, L = 0.984 + 0.993 x X₁; and forlarvae subjected to net-capture simulation then stored in alcohol,L = 0.532 + 0.989 x X₁ where L = live standard length and X₁= standard length after storage. The non-linear regression formulaparameterized by Theilacker (Fish. Bull US, 78,685–692,1980) for northern anchovy larvae provided a good fit to thedata for herring larvae subjected to net-capture simulationand then stored in formaldehyde. However, the model had to bere-parameterized to provide a good fit for larvae stored inalcohol. The precision achieved in length measurements usinga computer-aided measuring system is also discussed.     

Drinking and water absorption by the larvae of herring (Clupea harengus) and turbot (Scophthalmus maximus)

The efficiencies of water absorption from the guts of the larvae of herring ( Clupea harengus L.) and turbot ( Scophthalmus maximus L.) were estimated by two methods, The first method was based on the differences in the rates of accumulation, by drinking, and clearance from the gut of radiolabelled inert markers. The second method used the equilibrium level of radioactivity in the larvae to measure the concentration of the markers in the gut above background as water is absorbed from the gut. Water absorption efficiencies for herring larvae drinking sea water were estimated to be 77% using both methods. When external salinity was reduced to 50% sea water, drinking rates and water absorption efficiency in herring larvae fell substantially.
Estimates of water absorption efficiency of seawater-adapted turbot larvae were similar (71–84%) to that of herring using both methods. Although temperature had a marked effect on both the rate of drinking and water absorption, there was no significant thermal effect on the efficiency of absorption from the guts of turbot larvae. The limitations of the techniques and the implications of the estimates in terms of water balance in fish larvae are discussed.     

Morphology of the excretory system of Hysterothylacium haze (Nematoda: Anisakidae: Raphidascaridinae)

The morphology of the excretory system of Hysterothylacium haze was examined by serial histological sections. The excretory system was H-shaped and glandular, consisting of lateral filaments and a commissure, with the exretory pore opening posterior to the nerve ring. A large excretory nucleus was present in the left filament. The cuticularized excretory duct was confined to the left side of the commissure. The glandular excretory system is rare among the Raphidascaridinae.     

Effect of different holding regimens on the intestinal microflora of herring (Clupea harengus) larvae.

The aerobic intestinal microflora of 2-week-old herring (Clupea harengus) larvae was characterized by using conventional microbiological methods and electron microscopy. Larvae were hatched and kept in filtered seawater or in seawater with penicillin and streptomycin. The gastrointestinal tract of herring larvae is essentially a straight tube divided into two compartments. Light microscopy revealed bacteria present in a progressively increasing amount throughout the length of the gastrointestinal tract from esophagus to anus. The posterior region of the intestinal lumen appeared completely occluded with bacteria. The intestinal microflora consisted mainly of members of the genera Pseudomonas and Alteromonas in the larvae incubated in filtered seawater, whereas Flavobacterium spp. dominated in larvae exposed to antibiotics. The intestinal microflora of untreated fish larvae was sensitive to all tested antibiotics, whereas multiple resistance was found in the intestinal microflora of the group given antibiotics. Thus, a dramatic change in the microflora resulted from incubation with antibiotics. Nonpigmented yeasts were detected in both larval groups. Ciliated epithelial cells were observed in the midgut, probably propeling bacteria towards the hindgut, where endocytosis of bacteria has been demonstrated. These findings suggest that transport and sequestering mechanisms resembling those of invertebrates may be found in the gut of fish larvae. The possible significance for larval health and nutrition is discussed.     

Experimental studies on the migration of Anisakis sp. larvae (Nematoda: ascaridida) into the flesh of herring, Clupea harengus L.

In two experiments, a batch of 38 herring from Shetland was gutted immediately on capture (0 h) and further batches were gutted 14 and 37 h after capture and storage on ice. The numbers of Anisakis larvae in the body-cavity and in the flesh (detected by pepsin-HCl digest) were then counted. The proportion of fish with worms in the flesh was higher at 14 and 37 h than at 0 h. The percentage of the total worm burden in the flesh increased between cash each time interval, which suggests that a large-scale migration of larvae into the flesh occurs in ungutted fish. There was a positive association between the numbers of larvae in the viscera and the numbers in the flesh. Most larvae occurred in the hypaxial muscles. The results are discussed in relation to the observations of earlier workers.     

Electrophoretic identification of Anisakis sp. larvae (Ascaridida: Anisakidae) from Clupea harengus L. in Baltic Sea

On the basis of electrophoretic studies carried out on 15 gene-enzyme systems, 80 Anisakis sp. larvae from the herring Clupea harengus, fished in South Baltic Sea and Gdanisk Bay, were identified as Anisakis simplex B. This is the first record of Anisakis simplex B in the Baltic Sea. The spawning migration of the herrings from the North Sea to the Baltic Sea and the distribution of A. simplex B are briefly discussed.     

Effect of different holding regimens on the intestinal microflora of herring (Clupea harengus) larvae.

The aerobic intestinal microflora of 2-week-old herring (Clupea harengus) larvae was characterized by using conventional microbiological methods and electron microscopy. Larvae were hatched and kept in filtered seawater or in seawater with penicillin and streptomycin. The gastrointestinal tract of herring larvae is essentially a straight tube divided into two compartments. Light microscopy revealed bacteria present in a progressively increasing amount throughout the length of the gastrointestinal tract from esophagus to anus. The posterior region of the intestinal lumen appeared completely occluded with bacteria. The intestinal microflora consisted mainly of members of the genera Pseudomonas and Alteromonas in the larvae incubated in filtered seawater, whereas Flavobacterium spp. dominated in larvae exposed to antibiotics. The intestinal microflora of untreated fish larvae was sensitive to all tested antibiotics, whereas multiple resistance was found in the intestinal microflora of the group given antibiotics. Thus, a dramatic change in the microflora resulted from incubation with antibiotics. Nonpigmented yeasts were detected in both larval groups. Ciliated epithelial cells were observed in the midgut, probably propeling bacteria towards the hindgut, where endocytosis of bacteria has been demonstrated. These findings suggest that transport and sequestering mechanisms resembling those of invertebrates may be found in the gut of fish larvae. The possible significance for larval health and nutrition is discussed.     

Differential utilization of storage lipids and storage proteins by Northwest Atlantic herring (Clupea harengus harengus)

Utilization of storage lipids and storage proteins by non-feeding north-west Atlantic herring was assessed under conditions of: (1) concurrent gonad maturation and overwintering periods with differing rates of gonad development for males and females (spring-spawncrs); (2) overwintering, reproductively dormant and spent males and females (autumn-spawners); and (3) approximately equivalent rates of gonad development during late summer for males and females (autumn-spawners). Storage lipids were depleted by all non-feeding fish but storage proteins were depleted only by herring with measurable gonad development during the observation period independently of season (female spring-spawners, maturing male and female autumn-spawners). The analyses indicate that storage lipids sustain routine and active metabolism while storage proteins are utilized to develop gonad. Therefore, the relative investment into reproduction versus routine and active metabolism can be evaluated separately for non-feeding herring using readily obtainable tissue proximate composition data.     

Characterization of creatine kinase isoforms in herring (Clupea harengus) skeletal muscle

It is known that mitochondrial creatine kinase (MtCK) in mammals is always expressed in conjunction with one of the cytosolic forms of creatine kinase (CK), either muscle-type (MM-CK) or brain-type (BB-CK) in tissues of high, sudden energy demand. The two creatine kinase (CK) isoforms were detected in herring (Clupea harengus) skeletal muscle: cytosolic CK and mitochondrial CK (MtCK) that displayed the different electrophoretic mobility. These isoforms differ in molecular weight and some biochemical properties. Isolation and purification procedures allowed to obtain purified enzymes with specific activity of the 206 μmol/min/mg for cytosolic CK and 240 μmol/min/mg for MtCK. Native M_rs of the cytosolic CK and MtCK determined by gel permeation chromatography were 86.000 and 345.000, respectively. The results indicate that one of isoforms found in herring skeletal muscle is a cytosolic dimer and the other one, is a mitochondrial octamer. Octamerization of MtCK is not an advanced feature and also exists in fish. These values correspond well with published values for MtCKs and cytosolic CK isoforms from higher vertebrate classes and even from lower invertebrates.     

Cathepsin B- and L-like cysteine protease activities during the in vitro development of Hysterothylacium aduncum (Nematoda: Anisakidae), a worldwide fish parasite

Proteinases play an important role as virulence factors both in the life-cycle of parasites and in the pathogen–host relationship. Hysterothylacium aduncum is a worldwide fish parasite nematode which has been associated with non-invasive anisakidosis and allergic responses to fish consumption in humans. Cysteine proteinases have been associated with allergy to plant pollens, detergents and dust mites. In this study the presence of two types of cysteine proteinases (cathepsin B and cathepsin L) during in vitro development of H. aduncum is investigated. Specific fluorescent substrates were used to determine cathepsin activities. The activity detected with substrate Z-FR-AMC was identified as cathepsin L (optimum pH = 5.5; range 3.5–6.5). Cathepsin B activity was only identified with Z-RR-AMC (optimum pH = 7.0–7.5; range 5.0–8.0). The start of cultivation led to increased activity of both cathepsins (1.8-fold for cathepsin B and 6.3-fold for cathepsin L). These activities varied according to the developmental stage. Cathepsin B activity decreased after M4, returning to its initial level. Cathepsin L activity also decreased after M4, but still maintained a high level (4–6 times the initial level) in adult stages. Having considered these activity variations and the optimum pH values, we suggest that cathepsin L has a role in digestive processes while cathepsin B could be involved in cuticle renewal, among other possible functions.     

Long-term survey data (1965-1972) on the occurrence of Anisakis larvae (Nematoda: Ascaridida) in herring, Clupea harengus L., from the North Sea

The occurrence of larval Anisakis in North Sea herring was examined during the period 1965-1972 using a sampling method which yielded comparable data for all eight years. Data on abundance of infestation in several herring stocks pointed to remarkable fluctuations over the study period with an increase in the period 1966-1968 followed by a decrease in the period 1968-1972. Of various hypotheses that may explain this situation, it is concluded that changes in the migration behaviour of the herring may be responsible. Other data and statistics are discussed with special reference to variations in infestation level in different samples and to the occurrence of adult nematodes in marine mammals.     

Ultrastructural study of chloride cells in the trunk epithelium of larval herring, Clupea harengus

Mitochondria-rich cells of the mid-trunk region of herring larvae, as revealed by DASPMI staining under fluorescent microscopy, were identified as chloride cells. The chloride cells were generally solitary, and seldom made direct contact with each other. The shape of the cells varied with position on the body wall, those in dorsal locations being more compressed in the apical/basal direction. The structure of the chloride cells was similar to that described for other teleost species but there were considerable differences between ventral and dorsal cells. The volume fraction of mitochondria and diameters of mitochondria, cristae, and terminal expansions of cristae were all smaller in the dorsal cells. Tubular network density was relatively constant whilst smooth endoplasmic reticulum (SER) density and vesicotubular density, of the subapical cytoplasm, exhibited a high variation which did not correlate with the presence or absence of accessory cells. The apical membranes of both cell types were flush with the epithelium and did not form a crypt, even when interdigitating processes of an accessory cell were present. Accessory cell interdigitations were generally observed for the apical membrane of ventral cells but were seldom observed in the more dorsal cells of the segmental bands. The ultrastructural evidence suggests that the ventral cells are functional in ion pumping whereas the majority of chloride cells of the dorsal segmental bands were probably not functional in ion pumping.     

Vertical migrations of herring,Clupea harengus,larvae in relation to light and prey distribution

Synopsis The influence of light and prey abundance on the vertical distribution of herring larvae was evaluated by three investigations made under calm weather conditions in the North Sea off the Scottish coast. The investigations took place at different time after hatching and the vertical distributions of three size groups of larvae (mean sizes 8,15 and 19 mm) were related to time of day and the vertical distribution of copepods. No migratory behaviour of copepods was observed but their vertical distribution differed between investigations. In the investigation on intermediate sized larvae, copepod density peaked at the pycnocline (40 m). Larvae concentrated at this depth at noon. At dawn and dusk larvae migrated towards the surface and the vertical distributions fluctuated semidielly. In the two other investigations, copepods were homogeneously distributed in the water column and after migration towards the surface at dawn larvae stayed in the upper water column during the day. The observations suggest that the daytime vertical distribution of larvae in calm weather is mainly determined by feeding conditions: the larvae move to depths were light is sufficient for feeding, and refinement within that zone is made according to a compromise between optimal light conditions for feeding and optimal prey densities.     

Molecular identification of two strains of third-stage larvae of Contracaecum rudolphii sensu lato (Nematoda: Anisakidae) from fish in Poland

Contracaecum sp. larvae (L3) from fish were identified using nucleotide sequences of the internal transcribed spacers ITS-1 and ITS-2 of the ribosomal DNA. The nematode larvae originated from fish in a freshwater situation (crucian carp Carassius carassius, from Selment Wielki Lake in Mazury, northeastern Poland) and a brackish-water region (Caspian round goby Neogobius melanostomus from the Baltic Sea, Gdafisk Bay at the Polish coast). Two strains (Contracaecum rudolphii A and B) of Contracaecum rudolphii senso lato, a parasite common at the adult stage in fish-eating birds, were identified. In fish from the freshwater site, only the strain temporarily designated C. rudolphii B was identified; in the brackish-water region, both strains were found, suggesting that fish serve as paratenic host for both genotypes. Contracaecum rudolphii sensu lato has been recorded in several species of fish-eating birds in Poland, particularly in the great cormorant, Phalacrocorax carbo, in which the abundance is highest. The results, although based on a restricted number of larvae, suggest that the life cycles of both genotypes can be completed in the Polish region and that at least one of them, C. rudolphii B, can develop both in fresh and brackish water.     

Influence of temperature on evasive responses of Atlantic herring larvae attacked by yearling herring, Clupea harengus L.

Predation encounters were staged in the laboratory between yearling herring, Clupea harengus L., 66 to 104 mm t.l. , and herring larvae, 8 to 30 mm t.l. ., at 8,11 and 14 o C. Video records were used to quantify prey behaviour. Prey responsiveness, reactive distance, response latency, and apparent looming threshold were not affected by temperature. Response speeds increased with temperature. Predator error rate and capture success showed no consistent thermal effects. Although the experiments could not fully evaluate the influence of temperature on the predators, results suggest that the predator's performance largely governs the outcome of an attack on a larva and that higher temperatures favour the predator by increasing the frequency of its encounter with prey.     

Purification and properties of malic enzyme from herring Clupea harengus spermatozoa

Herring spermatozoa exhibit higher activity of malic enzyme (ME) than Atlantic salmon (Salmo salar), brown trout (Salmo trutta), carp (Cyprinus carpio) and African catfish (Clarias gariepinus) spermatozoa. Two molecular forms of ME are present in herring spermatozoa: an NAD-preferring malic enzyme with very high activity and an NADP-specific malic enzyme with much lower activity (ratio about 33:1). NAD-preferring ME was purified by chromatography on DEAE-Sepharose, Red Agarose and Sephadex G-200 to a specific activity of 36 μmol/min/mg protein and NADP-specific ME on DEAE-Sepharose and 2′5′-ADP Sepharose. The molecular mass for NAD-preferring and NADP-specific ME determined by SDS-PAGE was equal to 61 and 64 kDa, respectively. High activity of ME suggests adaptation of herring spermatozoa to metabolism at high oxygen tension for herring spawn.     

The incidence of Anisakis sp. larvae (Nematoda: Ascaridata) in the commercially exploited stocks of herring (Clupea harengus L., 1758,) (Pisces: Clupeidae) in British and adjacent waters.

10 000 herrings from the commercial fisheries around the coasts of Great Britain and Ireland were examined for the nematode larva Anisakis sp. between October 1968 and October 1970. Heavy infestations were found in the North Sea stocks, moderate infestations west of Scotland and minimal infestations elsewhere; but nowhere was the parasite completely absent. Younger fish were often found to be more heavily infested than older fish and it is therefore suggested that the accumulation of larvae in the body cavity may be affected by annual fluctuations either in the population of an infested first intermediate host or in the extent to which the herrings are feeding on this host. A small but constant proportion of the parasites penetrate the musculature of the herring regardless of other factors such as the age or length of the host, or the number of other larvae present.