Turbidity enhances feeding abilities of larval Pacific herring,Clupea harengus pallasi

Fishes inhabiting estuaries, rivers, and embayments are subject to turbid conditions. Larvae of many fishes utilize estuaries as nursery areas. For visual plankton feeders such as larval fishes, turbidity may reduce search and reaction distances, resulting in lowered feeding abilities. In this study feeding Pacific herring larvae, Clupea harengus pallasi, were exposed to suspensions of estuarine sediment and Mount Saint Helens volcanic ash at concentrations ranging from 0 mg · l^–1 to 8 000 mg · l^–1. In all experiments, maximum feeding incidence and intensity occurred at levels of suspension of either 500 mg · l^–1 or 1000 mg · l^–1 with values significantly greater than controls (0 mg · l^–1). Feeding decreased at greater concentrations. The suspensions may enhance feeding by providing visual contrast of prey items on the small perceptive scale used by the larvae. Larval residence in turbid environments such as estuaries may serve to reduce predation from larger, visual planktivores, while searching ability in the small larval perceptive field is not decreased.     

Development of microsatellite loci in Pacific herring (Clupea pallasi)

Fifteen polymorphic di‐, tri‐ and tetranucleotide microsatellite markers were developed in Pacific herring (Clupea pallasi) to aid in the delineation of population structure of herring in British Columbia. Twelve of the microsatellite loci were analysed in over 4000 wild herring. Expected heterozygosities ranged 0.73–0.95, and only two loci significantly deviated from Hardy–Weinberg equilibrium.     

Comparison of fatty acid profiles of spawning and non-spawning Pacific herring, Clupea harengus pallasi

Crude lipid and fatty acid composition from liver, intestine, roe, milt and flesh of spawning and non-spawning Pacific herring (Clupea harengus pallasi) were examined to determine the relative effects of spawning on the nutritional value of herring. Depletion of lipid due to spawning condition was significant (P < 0.01) in all organ tissues and flesh of spawning herring. The lipid content ranged from an average of 1.9 to 3.4% (wet weight basis) in different organ tissues of spawning herring, to 10.5 to 16% in non-spawning fish. The fatty acid profile exhibited many differences in the relative distribution of individual fatty acids among organ tissues and between the two fish groups. Oleic acid (C18:1n-9), a major monounsaturated fatty acid (MUFA) found in all tissue lipids, decreased significantly (P < 0.01) in spawning fish. The two monoenes, C20:1n-9 and C22:1n-11, occurred at high concentrations in the flesh but at only minor proportion in the digestive organs and gonads. Spawning herring also had significantly (P < 0.01) higher polyunsaturated fatty acids (PUFA) content in the organ tissues, particularly in the milt and ovary, with docosahexaenoic acid (C22:6n-3, DHA) having the greatest proportion. Among the n-6 fatty acids, only C18:2n-6 and C20:4n-6 occurred at notable amounts and were present in higher proportions in spawning fish. We concluded that although relatively higher n-3 fatty acid content was found in the organ lipids of spawning herring, they are not an energy-dense prey food source due to the fact that both flesh and gonads contain a very low amount of lipid.     

Biological tags for stock separation in Pacific herring Clupea harengus pallasi in California.

A survey of the parasites of Pacific herring (Clupea harengus pallasi) off northern California identified 1 species of Acanthocephala, 1 species of Cestoda, 2 species of Copepoda, 1 species and 1 family of Digenea, 3 species of Nematoda, and 3 species of Protozoa. From this survey, Lacistorhynchus dollfusi (Cestoda), Parahemiurus merus (Digenea), and Anisakis simplex, Contracaecum sp., Hysterothylacium sp. (Nematoda) were selected as potential tags. Herring were collected in Tomales, San Francisco, and Monterey bays for the following 9 yr and examined for these select parasites. The results suggest that these parasites can be used to distinguish the spawning stocks of San Francisco and Tomales bays. The distribution of the definitive hosts of the respective parasites suggests that the Tomales Bay fish are offshore during the nonbreeding season and the San Francisco Bay fish onshore. The similarity in parasitism between San Francisco Bay and the nonspawning population in Monterey Bay suggests that these 2 populations represent a single stock.     

Pathogenicity of Ichthyophonus hoferi for laboratory-reared Pacific herring Clupea pallasi and its early appearance in wild Puget Sound herring

Laboratory-reared pathogen-free Pacific herring were exposed to pure cultures of Ichthyophonus hoferi, and reproduced the disease seen in naturally infected fish--thus fulfilling Koch's Postulates. Pathogen-free herring used in this study were reared from artificially spawned eggs incubated in filtered, UV-sterilized seawater, eliminating the variables associated with multiple infections, which are common in wild herring. Wild free-ranging herring were captured monthly from June through October by dip net from 'herring balls' located in the northern Puget Sound. I. hoferi infections were identified in these fish soon after metamorphoses, about 4 mo post-hatch. The prevalence increased from 5 to 6% in 0-yr fish to 24% in 1-yr-old fish to 50 to 70% in fish over 2 yr old, with no associated increase in mortality. The route of natural transmission to wild herring was not determined, but carnivorous fish became infected and died when they were experimentally fed tissues infected with the organism. In vitro culture of tissues was the most sensitive method for identifying both clinical and subclinical infections.     

Two egg-derived molecules in sperm motility initiation and fertilization in the Pacific herring (Clupea pallasi)

Sperm of the Pacific herring are immotile at spawning. Two egg-derived molecules are capable of initiating sperm motility. One is herring sperm activating protein(s) (HSAPs) and the other is sperm motility initiation factor (SMIF). These two motility initiators differ in their location and association with the chorion, and in thier isoelectric points and molecular weights. In this study we have investigated the roles of these two inducers with respect to motility and fertilization. Using computer analysis of sperm motility, we found that HSAPs, as well as the C-terminal HSAPs peptide, elicit a linear motility pattern, while SMIF induced a highly circular and asymmetric pattern. HSAPs induced a two-fold increase in intracellular calcium, whereas SMIF induced a four-fold increase of motility initiation. SMIF-exposed sperm, preloaded with BAPTA-AM, showed a more linear motility and this motility trajectory decreased with their fertilizing capability. The difference in intracellular calcium levels between HSAPs and SMIF is consistent with the observed linear and circular motility. In the absence of SMIF, HSAPs do not support fertilization. Fertilization is rescued in these experiments if SMIF is reintroduced. We propose that diffusible HSAPs are not essential for fertilization, but enhance sperm-egg collisions via linear motility. SMIF, which is bound to the micropylar region of the chorion, is required for fertilization and induces circular motility that is a prerequisite for sperm to enter the micropylar canal and fertilize the egg.     

Weight loss and change of condition factor during fixation of Pacific herring, Clupea harengus pallasi, eggs and larvae

Dry weights of unfixed eggs and larvae of Pacific herring, Clupea harengus pallasi , taken at six different periods during development, were compared to those of larvae stored for 10 days in fixatives varying in salinity (0, 15, 28%‰) and formalin (4, 10, 20%) concentration. In most instances there was some weight loss of the fixed specimens. In general weight loss varied inversely with salinity and formalin concentration and was greater in larvae than eggs. Weight loss was greatest in recently fertilized eggs and decreased in older eggs. Weight loss in recently hatched larvae varied from 19 to 36% depending upon the salinity and formalin concentration. Weight loss varied inversely with larval size and fixation increased weight in some large larvae. Weight change during fixation could result in an artificial inflation of the estimate of condition factors, particularly in the younger smallest larvae.     

Purification and characterization of prolyl endopeptidase from the Pacific herring, Clupea pallasi, and its role in the activation of sperm motility

Protease activities with specificity toward synthetic substrates, Suc-Gly-Pro-Leu-Gly-Pro-MCA for prolyl endopeptidase or collagenase-like peptidase, and Suc-Ala-Ala-Pro-Phe-MCA for chymotrypsin were identified in the detergent-soluble fraction of herring spermatozoa. The enzyme activities increased in the presence of herring sperm-activating protein (HSAP). Among them a prolyl endopeptidase [EC. 3. 4. 21. 26] was purified to near homogeneity from herring testis. The molecular mass of the enzyme was 79 kDa and the properties of the enzyme were quite similar to prolyl endopeptidase from other tissues or cells. Both the enzyme activation and the sperm motility activation by HSAP were inhibited by benzyloxycarbonyl-L-thioproline-thioprolinal, a specific inhibitor for prolyl endopeptidase. Furthermore, the motility activation by HSAP was inhibited by substrates of the prolyl endopeptidase. Western blotting with mouse anti-prolyl endopeptidase serum revealed the presence of 79 kDa prolyl endopeptidase in the tail fraction of herring sperm. These results suggest that prolyl endopeptidase exists on the surface of the sperm tail and interacts with the HSAP.     

Production and characterization of monoclonal antibodies to IgM of Pacific herring (Clupea pallasii)

Pacific herring (Clupea pallasii) have a central role in the North Pacific ecosystem as a forage fish species and are natural reservoirs of several important finfish pathogens, including Viral hemorrhagic septicemia virus (VHSV). Here, we report the identification of the gene encoding the immunoglobulin mu (IgM) heavy chain, as well as the development and characterization of monoclonal antibodies (MAbs) that specifically react with Pacific herring IgM. Pacific herring immunoglobulin was purified and consisted of heavy and light chains of approximately 80 and 25?kDa. Three hybridoma clones were initially identified by ELISA as reactive with purified immunoglobulin but only one clone was able to detect an 80?kDa protein in Pacific and Atlantic herring (Clupea harengus) whole plasma by denaturing western blot. However, all three MAbs were able to precipitate an 80?kDa protein from Pacific herring and LCMS sequencing of peptide fragments derived from this protein matched the predicted amino acid sequence of the cloned, heavy chain gene. In addition, two of the MAbs stained cells within the putative lymphocyte gates for the spleen, anterior kidney and posterior kidney but were not reactive for myeloid/granulocyte gates, which is consistent with these MAbs reacting with surface IgM(+) B-cells. To our knowledge, this is the first report of IgM-related gene sequences and anti-IgM monoclonal antibodies from any member of the family Clupeidae. The antibodies produced in this study are critical for achieving our long-term goal of conducting serological surveillance to assess pathogen exposure in natural populations of Pacific herring.     

The nomenclature of the Pacific herring, Clupea pallasü Valenciennes, 1847

Confusion over the nomenclature of the Pacific herring is shown to have stemmed from the comparison of it with White Sea herring which was mistakenly assumed to be conspecific with Atlantic herring.     

Sperm-activating proteins from unfertilized eggs of the Pacific herring, Clupea pallasii

Ripe unfertilized eggs of the Pacific herring, Clupea pallasii , release sperm-activating proteins into seawater at the time of fertilization. Five species of herring sperm-activating proteins (HSAP) with different pl values (4.8, 4.9, 5.0, 5.1 and 5.4) were purified from the egg-conditioned medium by gel filtration and isoelectric focusing. Molecular mass of the HSAP (pl = 5.1), the major species of the five HSAP, was determined to be 8.1 kDa by mass spectrometry. Molecular weights of all of the HSAP were estimated to be 7700 by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The first 20 amino acid sequences from N-terminal ends of three HSAP (pl = 4.9, 5.0 and 5.1) were almost identical, suggesting that the HSAP have similar structures.     

Development and characterization of a cell line from Pacific herring, Clupea harengus pallasi, sensitive to both naphthalene cytotoxicity and infection by viral hemorrhagic septicemia virus

A cell line, PHL, has been successfully established from newly hatched herring larvae. The cells are maintained in growth medium consisting of Leibovitz's L-15 supplemented with 15% fetal bovine serum (FBS), and have been cryopreserved and maintain viability after thawing. These cells retain a diploid karotype after 65 population doublings. PHL are susceptible to infection by the North American strain of viral hemorrhagic septicemia (VHS) virus, and are sensitive to the cytotoxic effects of naphthalene, a common environmental contaminant. Naphthalene is a component of crude and refined oil, and may be found in the marine environment following acute events such as oil spills. In addition, chronic sources of naphthalene contamination include offshore drilling and petroleum contamination from areas such as docks and marinas that have creosote-treated docks and pilings and also receive constant small inputs of petroleum products. This cell line should be useful for investigations of the toxicity of naphthalene and other petroleum components to juvenile herring. In addition, studies of the VHS virus will be facilitated by the availability of a susceptible cell line from an alternative species.     

Spatial and Temporal Variability in Juvenile Pacific Herring, Clupea pallasi, Growth in Prince William Sound, Alaska

We examined the spatial and temporal variability of juvenile Pacific herring, Clupea pallasi, growth within Prince William Sound, Alaska. Pacific herring, ranging from post-larval to mature fish, were collected from four spatially segregated bays between October 1995 and March 1998. Linear growth equations from each bay were similar. However, growth rates and wet weight-at-length, reflecting condition, of juvenile Pacific herring cohorts varied seasonally and annually. The short term spatial variability in juvenile Pacific herring growth suggested that each bay was a unique nursery area. The physical and biological conditions within each bay appeared to dictate Pacific herring growth rate.     

Hatch-period-dependent early growth and survival of Pacific herring Clupea pallasii in Miyako Bay, Japan

Considerable interannual variation in the abundance of larval and juvenile Pacific herring Clupea pallasii was detected in Miyako Bay, on the Pacific coast of northern Japan; abundances were high in 2001 and 2003 and low in 2000 and 2002. Hatch dates and growth rates for larval and juvenile survivors were estimated through otolith analysis. Water temperature and food availability were monitored on the spawning and nursery grounds in the inner part of the bay. The number of spawning females caught in nets set around the spawning ground was recorded during each spawning season (January to May) in 2000–2003. No correlation was found between the number of spawning females and the abundance of larvae and juveniles on the spawning and nursery grounds. The hatch dates of surviving larvae and juveniles were concentrated at the end of the spawning season in 2001 and in the middle of the season in 2003. The larvae experienced relatively high prey concentrations during the first-feeding period in 2001 but low concentrations in 2003. Survival of larvae during the first-feeding period may be a function of prey concentration as well as water temperature. In 2003, low water temperature would reduce starvation mortality during the first-feeding period. In contrast, unfavourable feeding conditions with higher temperatures during the first-feeding period seemed to result in low larval survival in 2000 and 2002. The 2001 larvae grew faster than those in 2003 because of the late hatch dates and the higher ambient temperatures that resulted. Temperature might be a major factor controlling growth rates of C. pallasii larvae in Miyako Bay.     

Preliminary data on variation of four microsatellite loci in Pacific herring Clupea pallasii

Variation of microsatellite loci Cpa 10, Cpa 113, Cpa4, and Cpa7 was for the first time examined in Pacific-type herring Clupea pallasii from the White Sea (CI. pallasii marisalbi), the Kara Sea (CI. pallasii suworowi), the Sea of Okhotsk, and Lake Nerpich'e, Kamchatka Bay, northwestern Pacific (CI. pallasiipallasii). All loci exhibitedhigh genetic diversity. The estimates of expected heterozygosity varied from 41.5 to 95.6% (mean, 82%). The level of pairwise genetic differentiation Fst at all microsatellite loci varied from 0.005 to 0.076 (0.019, on average) and t was statistically significant (P < 0.05) in most of the pairs of herring samples. Estimates of genetic differentiation among the herring of one subspecies were lower than between the groups belonging to different subspecies.     

Dynamics of viral hemorrhagic septicemia, viral erythrocytic necrosis and ichthyophoniasis in confined juvenile Pacific herring Clupea pallasii

Capture of wild, juvenile herring Clupea pallasii from Puget Sound (Washington, USA) and confinement in laboratory tanks resulted in outbreaks of viral hemorrhagic septicemia (VHS), viral erythrocytic necrosis (VEN) and ichthyophoniasis; however, the timing and progression of the 3 diseases differed. The VHS epidemic occurred first, characterized by an initially low infection prevalence that increased quickly with confinement time, peaking at 93 to 98% after confinement for 6 d, then decreasing to negligible levels after 20 d. The VHS outbreak was followed by a VEN epidemic that, within 12 d of confinement, progressed from undetectable levels to 100% infection prevalence with >90% of erythrocytes demonstrating inclusions. The VEN epidemic persisted for 54 d, after which the study was terminated, and was characterized by severe blood dyscrasias including reduction of mean hematocrit from 42 to 6% and replacement of mature erythrocytes with circulating erythroblasts and ghost cells. All fish with ichthyophoniasis at capture died within the first 3 wk of confinement, probably as a result of the multiple stressors associated with capture, transport, confinement, and progression of concomitant viral diseases. The results illustrate the differences in disease ecology and possible synergistic effects of pathogens affecting marine fish and highlight the difficulty in ascribing a single causation to outbreaks of disease among populations of wild fishes.     

Occurrence and survival of the larval nematode Anisakis sp. in the flesh of fresh, frozen, brined, and smoked pacific herring, Clupea harengus pallasi

Two hundred and twenty Pacific herring (Clupea harengus pallasi) from Yaquina Bay, Oregon, were divided into five groups to test the effects of various methods of handling and processing (fresh, frozen, brined, cold smoked, and cold smoked-gibbed) on the occurrence and survival of Anisakis larvae in the flesh. Viscera and flesh were digested separately using a pepsin-HC1 technique, and counts were taken of Anisakis larvae. Parasite loads were statistically largest in the flesh of frozen, brined, and smoked fish. Smoked fish harbored the greatest proportions of larvae in the flesh. Human consumption of brined or cold smoked Pacific herring represents a potential public health hazard.     

Comparative parasitological analysis of White Sea herring fry (Clupea pallasi n. maris-albi) raised experimentally and caught at sea

Dynamics of the infection with pathogen trematodes of Brachyphallus crenatus (Rud., 1802) and Lecithaster gibbosus (Rud., 1802) in larvae and juvenile herring reared in experimental conditions and in those which were caught in the sea has been observed. Simultaneous infection of juvenile herring in natural environments and in experimental conditions has been noted. The parasitological examination of the material suggests the degree of natural mortality of larvae in the sea. The total rate of the juvenile herring infection in nature ranges from 22 to 92%.