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1.
This study examines the relationships between first year growth of juvenile Prince William Sound herring, temperature and their food. We present time series of herring first year growth, determined from scale measurements as a proxy for herring length, water temperature and indices of multiple trophic levels of plankton obtained from Continuous Plankton Recorder (CPR) sampling on the adjacent Gulf of Alaska shelf. We show that there was a significant correlation between herring growth and water temperature, when the three warmest years were excluded (the mean July and August temperatures were greater than 12.5°C in 1989, 2004 and 2005). There were also strong, significant relationships between the abundance of appropriately sized (for first‐feeding herring) planktonic prey groups and herring growth. First year herring growth was greater in years with higher abundances of diatoms, microzooplankton and small mesozooplankton but not related to variability in abundance of larger mesozooplankton (such as euphausiids and large copepods). Furthermore, the strong interannual relationship between diatoms and herring growth held true even in the warmest years where the relationship between temperature and growth broke down. We also found seasonal timing and abundance changes in the plankton in warm years that would make the prey more abundant during the summer months immediately after metamorphosis of the herring larvae. We thus conclude that young‐of‐the‐year herring may grow better in warm years because the timing of key prey is a better match for their first feeding.  相似文献   

2.
《Fisheries Research》2007,84(2-3):319-331
Pacific herring (Clupea pallasii) and walleye pollock (Theragra chalcogramma) are important forage species in the North Pacific Ocean, but their seasonal abundance patterns are poorly known. During three consecutive years of monthly acoustic surveys in Lynn Canal, southeastern Alaska, large schools of herring dominated during winter and were present in a 60-km long submarine gully; this gully appears to provide critical winter habitat for herring when their prey are less available and energy expenditure must be reduced. The salient change in pollock distribution is a shift from shallow waters during summer to deeper waters during winter, such that shallow (<40 m) waters are nearly devoid of pollock during winter. The shift presumably occurs in response to the build-up of secondary productivity during summer and predator avoidance during winter. The seasonal changes in herring abundance drove seasonal changes in predator abundance, as Steller sea lions (Eumetopias jubatus) and humpback whales (Megaptera novaeangliae) preyed upon the winter aggregation of herring. Such seasonal links likely serve an important role in structuring trophic relationships in the North Pacific Ocean ecosystem.  相似文献   

3.
The daily mortality rates of North Sea herring early‐stage larvae are found to vary over decades. Larval abundance data were used with a spatio‐temporal oceanographic model to reconstruct temperature histories of the observed larvae. The histories were used in conjunction with a temperature‐based growth model to estimate larval age. Mean daily mortality rates were then estimated for the four spawning components (Downs, Banks, Buchan and Orkney/Shetland) using the vertical life table approach, which considers instantaneous abundances across all ages rather than following distinct cohorts. All spawning components, but especially Downs (in the south), exhibited a steady rise in mortality associated with increasing population size. In addition, the three northern components shared a distinct trend in mortality that was significantly correlated with ambient water temperatures experienced by the larvae during the respective time periods after hatching. This trend was also significantly negatively correlated with the residuals of the whole stock‐recruitment relationship. These findings were generally robust to assumptions about growth and hatch length of larvae. The compensatory increase in productivity in the late 1980s and poor recruitment since 2000 coincide with changes in the mortality of larvae younger than 30 days post hatch and covary with larval density and temperature. Thus we suggest that the mortality of early‐stage larvae does impact on the population dynamics in North Sea herring in its current productivity regime, implying a critical period in the determination of year class strength.  相似文献   

4.
A larval survey is used in the annual assessment as an index of the spawning stock size of Norwegian spring spawning herring (Clupea harengus). To test how inter‐annual fluctuations in circulation pattern, survey design and execution of the survey affected the larval abundance estimate we conducted simulated surveys using a model framework with idealized assumptions to model larval drift and sampled larvae using several realistic survey scenarios. The results suggest that inter‐annual variations in circulation pattern alone can have a profound effect on the perception of larvae abundance and that the direction of the survey (north to south versus south to north) can have a significant effect on the estimated abundance, particularly if hatching occurs over a short period of time. Additionally, disruptions to a continuous survey schedule also have an effect and, as such, sampling strategies in case of disruption to the survey are proposed.  相似文献   

5.
Regular weekly sampling of larvae with a Hensen net in the stationary stations on the main spawning grounds of the brackishwater herring population in the Gulf of Riga was carried out in 1947–2004. Probably due to the rapidly increasing anthropogenic eutrophication and the rising winter temperature the yearly abundance of herring larvae has significantly increased with a shift in the average abundance in 1972/1973. Correlation of the average number of herring larvae with the year-class strength was significant for the intermediate (10–16 mm, P < 0.05) and large (≥17 mm, P < 0.001) larval size groups. The monthly average air temperature in the period from January to March was the main environmental variable regulating the abundance of the year classes (P < 0.001). The dependence between the spawning stock biomass (SSB) and year-class abundance differed by climate periods. In the period of cold winters environmental conditions dominated in determination of the year-class abundance whereas the role of the SSB was nonsignificant (P > 0.05). In the period of milder winters the importance of the SSB in determination of the abundance of year classes considerably increased and it significantly correlated with the abundance of year classes (P < 0.05). The winter–spring temperatures and other climatic variables presumably control the abundance of the forming year-class during the period of the highest larval mortality mainly via the production of their food.  相似文献   

6.
We examined the distribution of Atlantic bluefin tuna ( Thunnus thynnus ) in the Gulf of Maine, Northwest Atlantic Ocean, from 17 to 23 August 1995, in relation to physical and biological parameters. Specifically, we fit a binomial GLM to the bluefin tuna presence–absence data and predictor variables that include: sea surface temperature (SST), ocean depth, distance to an SST front, time-lagged density of SST fronts, and an interpolated surface of Atlantic herring ( Clupea harengus ) density. In addition, we use simple and partial Mantel tests to examine whether bluefin tuna presence–absence data are significantly associated with these predictors, once spatial autocorrelation is accounted for. Results suggest that the distribution of bluefin tuna significantly correlated with herring density ( z  =   3.525, P  =   0.000424), and that inclusion of biological variables results in a more parsimonious model. Mantel tests results indicate that bluefin tuna abundance is significantly correlated with herring density after the effect of spatial structure is removed (Mantel r  =   0.043, P  <   0.019).  相似文献   

7.
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8.
Understanding the recruitment variability of the Atlantic herring North Sea stock remains a key objective of stock assessment and management. Although many efforts have been undertaken linking climatic and stock dynamic factors to herring recruitment, no major attempt has been made to estimate recruitment levels before the 20th century. Here, we present a novel annually resolved, absolutely dated herring recruitment reconstruction, derived from stable carbon isotope geochemistry (δ13C), from ocean quahog shells from the Fladen Ground (northern North Sea). Our age model is based on a growth increment chronology obtained from fourteen shells. Ten of these were micromilled at annual resolution for δ13C analysis. Our results indicate that the anthropogenically driven relative depletion of 13C, the oceanic Suess effect (oSE), became evident in the northern North Sea in the 1850s. We calculated a regression line between the oSE‐detrended δ13C results (δ13C?) and diatom abundance in the North Sea, the regression being mediated by the effect of phytoplankton on the δ13C of the ambient dissolved inorganic carbon. We used this regression to build an equation mediated by a nutritional link to reconstruct herring recruitment using δ13C?. The reconstruction suggests that there were five extended episodes of low‐recruitment levels before the 20th century. These results are supported by measured recruitment estimates and historical fish catch and export documentation. This work demonstrates that molluscan sclerochronological records can contribute to the investigation of ecological baselines and ecosystem functioning impacted by anthropogenic activity with implications for conservation and stock management.  相似文献   

9.
The marine survival of hatchery-reared Atlantic salmon (Salmo salar) and sea trout (Salmo trutta) was examined in relation to marine conditions during post-smolt migration and in relation to stock traits. In 1970–2001, Carlin-tagged smolts were released in the Iijoki and Oulujoki rivers, the northern Baltic Sea. When both species were analysed together, the abundance of the three prey fish, herring (Clupea harengus), smelt (Osmerus eperlanus) and vendace (Coregonus albula) correlated positively with the survival of salmonids. In addition, the increase in smolt size appeared to improve the survival rate. Sea surface temperature (SST) may have affected indirectly through the abundance of prey fish during the post-smolt migration of salmon and sea trout. The smelt and vendace showed a statistical effect on survival only when the temperature effects were not included in the models. In sea trout, an increasing smolt length was not significantly correlated with the survival in good herring recruitment years, but in poor years survival increased very rapidly with increasing smolt size. The recapture rates of the salmonids tended to decrease between the years 1970 and 2001. During the same time period, the June SST slightly decreased. The positive correlation between the annual summer SST and recapture rate of salmon may partly explain the decreasing trend in recapture rates. An increase in smolt size did not compensate for the decline in the recapture rate of either species.  相似文献   

10.
Fish swimbladders, where present, contribute most to the scattering of sound by fish, as measured by the target strength (TS). The volumes of the swimbladders of two different European stocks of Atlantic herring were compared to consider the effect on estimates of TS. Swimbladder volumes of Baltic and Norwegian spring-spawning herring (Clupea harengus) were measured, together with individual herring fat content. Swimbladder volumes were found to differ significantly between the two herring stocks. Baltic herring have a larger swimbladder volume, which is suggested to be associated with the fish's low fat content, which in turn may be linked to its specific energy budget and the low salinity of the Baltic Sea. A buoyancy model that considered the different salinity conditions and fat proportions was used to evaluate the observed differences in swimbladder volume. The swimbladder volume data were subsequently used to model the mean target strength as a function of depth and growth pattern. Backscattering of the swimbladder was modelled using the modal-series-based deformed-cylinder model (MSB-DCM), describing the swimbladder as a gas-filled, elongated prolate spheroid. The fish body component was modelled as a fluid-filled ellipsoid using the distorted wave Born approximation (DWBA). Modelling results support a different TS-to-size relationship for Baltic herring, with a stronger echo, due to the larger swimbladder. Depth- and length-dependent TS relationships based on the model results are suggested.  相似文献   

11.
Capelin, herring, and red salmon diets were examined in relation to zooplankton abundance and biomass in the water column and surface layer of Auke Bay, Alaska, during the spring bloom period, 1987 and 1988 (April through mid-June). Euphausiid eggs were the dominant prey of capelin in mid-May 1987. Pseu-docalanus spp. and barnacle nauplii dominated during the rest of the season. Capelin consumed Calanus spp. and Metridia spp. in April and Pseudocaknus and Cen-tropages abdominalis in May and June 1988. During May and June 1987, herring were eating primarily barnacle larvae and Oikopleura spp. During April 1988, herring consumed primarily Calanus spp. and barnacle nauplii. In late April and early May they shifted to Pseudocalanus and Thysanoessa raschii, and in late May and June they consumed Centropages abdominalis and barnacle cyprids. Outmigrating red salmon fry consumed primarily Oikopleura during both years, along with substantial quantities of barnacle larvae. These dietary changes roughly correspond with variations in the abundance of prey taxa in the plankton samples. Likelihood measures of niche breadth indicated that capelin sometimes consume prey in approximately equal proportions to its abundance. Niche overlap between the herring and capelin was greatest in April and early May. Niche overlap was also high between herring and red salmon during June, when herring were in shallow water to breed.  相似文献   

12.
Abstract

Until 1990 the western Baltic Sea spring herring has been extensively used as raw material for the processing industry of the former German Democratic Republic. Today North Sea herring and other Atlantic herring stocks are preferred and utilization of the Baltic Sea herring stock, which has been caught between January and May around the Island of Rügen and in the Greifswalder Bodden, has dropped down dramatically. The reduction in exploitation of this resource is connected to enhanced quality specification required by German herring processing companies after reunion of both states.

In this study the quality of Baltic Sea spring herring from ICES subdivisions 22 and 24 was assessed and following conclusions were obtained:

  • Processing possibilities of Baltic Sea spring herring are limited due to low fat content (5-8%), a slight dry and short fiber texture and a less typical flavour and taste.

  • Off-flavour and taste (tainting) which has been often observed until mid nineties disappeared within the last years.

  • Infestation rates and abundance of nematodes (Anisakisspp.) are comparable to North Sea herring stocks.

  • Contamination levels of organic and inorganic pollutants are far below legal limits.

Only gill net fishery and trap fishing are able to guarantee a continuous supply of desired size classes 2 and 3. Trial with pair trawl fishing did not show promising results.

Due to reorganization and reduction of local fishery activities during the past ten years, an increase of the annual landing capacity of more than 10,000 t is questionable in future.  相似文献   

13.
Variation in growth and body size during critical life history stages can have important implications for life history schedules and survivorship. For Pacific herring (Clupea pallasii), there is still debate as to whether juvenile body size is governed by density‐dependent or ‐independent processes and few have evaluated whether the relative importance of either process shifts over the course of early ontogeny. We used a unique data set consisting of seasonal measurements of abundance, body size, and spatial distribution within a semi‐enclosed basin of Puget Sound (Washington State, U.S.A.) to measure the relative importance of temperature and cohort abundance on body size at distinct time periods, and evaluated whether density‐dependent habitat shifts might be responsible for density‐dependent growth. Over the 9 years of sampling (2001–2010) midsummer body size was positively related to temperatures experienced during the egg/yolk sac and larval stages and unrelated to cohort abundance. However, fall body size was negatively correlated with abundance and uncorrelated with both midsummer body size and temperature, indicating a shift from density‐independent to density‐dependent control over the course of the growing season. Thus, density‐dependent effects may supplant density‐independent effects exhibited early in herring life history. Our data on spatial distributions of herring and their zooplankton prey indicate that density‐dependent reductions in growth may be explained by density‐dependent habitat shifts that lead to reduce overlap of herring with zooplankton. Evidence of density‐dependent growth in marine fish populations is often attributed to exploitative competition, but our results suggest that these patterns may partly be mediated by density‐dependent distribution expansions in to prey‐poor habitat.  相似文献   

14.
Five years of field, laboratory, and numerical modelling studies demonstrated ecosystem‐level mechanisms influencing the mortality of juvenile pink salmon and Pacific herring. Both species are prey for other fishes, seabirds, and marine mammals in Prince William Sound. We identified critical time‐space linkages between the juvenile stages of pink salmon and herring rearing in shallow‐water nursery areas and seasonally varying ocean state, the availability of appropriate zooplankton forage, and the kinds and numbers of predators. These relationships defined unique habitat dependencies for juveniles whose survivals were strongly linked to growth rates, energy reserves, and seasonal trophic sheltering from predators. We found that juvenile herring were subject to substantial starvation losses during a winter period of plankton diminishment, and that predation on juvenile pink salmon was closely linked to the availability of alternative prey for fish and bird predators. Our collaborative study further revealed that juvenile pink salmon and age‐0 herring exploit very different portions of the annual production cycle. Juvenile pink salmon targeted the cool‐water, early spring plankton bloom dominated by diatoms and large calanoid copepods, whereas young‐of‐the‐year juvenile herring were dependent on warmer conditions occurring later in the postbloom summer and fall when zooplankton was composed of smaller calanoids and a diversity of other taxa. The synopsis of our studies presented in this volume speaks to contemporary issues facing investigators of fish ecosystems, including juvenile fishes, and offers new insight into problems of bottom‐up and top‐down control. In aggregate, our results point to the importance of seeking mechanistic rather than correlative understandings of complex natural systems.  相似文献   

15.
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16.
A qualitative understanding of the long‐term variation in the population dynamics of Yellow Sea (YS) herring is particularly important for clarifying the evolutionary processes and driving mechanisms of the YS large marine ecosystem. Unfortunately, because of a lack of long‐term, continuous, and simultaneous monitoring data, the specific driving processes and mechanisms of climate effects on the population dynamics of YS herring remain largely unknown. In response to this scientific issue, we preliminarily propose the idea of reconstructing long‐term changes in YS herring abundance over the past 590 years (AD 1417–2004) based on historical documents and attempt to explore the impacts of climate on the population. Our results show that YS herring abundance maintained at a relatively high level from AD 1417 to 1870 (during the Little Ice Age); in contrast, the population declined significantly from AD 1870 to 2004 at different rates. In addition, we also found that there were strong relationships between the population abundance of YS herring and the Pacific decadal oscillation (PDO) and drought/flood cycles. We suggest that the fluctuations in YS herring abundance may be influenced by ocean–climatic circulation shifts throughout the North Pacific, especially the PDO.  相似文献   

17.
Abstract –  Matsalu Bay in the Väinameri (West-Estonian Archipelago Sea) is a relatively shallow but large bay. It is the only real delta estuary in the northern Baltic Sea. The fish fauna is strongly dominated by freshwater species such as perch Perca fluviatilis , roach Rutilus rutilus , white bream Blicca bjoerkna and rudd Scardinius erythrophthalmus . The study presents CPUE data describing annual and seasonal variations in the species composition, abundance and spatial distribution, based on 1 year of monthly samplings from August 2001 to August 2002 and routine coastal monitoring (in late July–early August) between 1994 and 2003. The bay can be divided into three rather distinct parts. The fish fauna of the inner part (salinity 0–2 p.p.t.) is different from two open parts and resembles that of freshwater lakes. In the openmost part (salinity usually 4–6 p.p.t.) some marine species, such as herring Clupea harengus membras , flounder Platichthys flesus and eelpout Zoarces viviparus may seasonally be abundant. Species composition and abundance of most species varies seasonally and interannually. Only the abundance of few species such as pike Esox lucius and pikeperch Stizostedion lucioperca was not impacted by seasonality. The most dynamic period in the bay is spring, when several species (some of them very rare in summer, such as herring and smelt Osmerus eperlanus ) enter the bay for spawning.  相似文献   

18.
Otolith increment width and larval fish data (length and weight) were used to develop an individual‐based model (IBM) to describe daily resolved growth rates of North Sea herring (Clupea harengus) larvae (Autumn Spawners) caught during International Herring Larvae Surveys in the ICES area IVa from 1990 to 1998. The model combines sagittal otolith readings (core and individual increment measurements), larval standard length and weight data, and solves an over‐determined set of linear system equations for all parameters using the method of least square residuals. The model consists of a matrix, which describes the increment width formation of 119 larvae, a vector containing their length/weight measurements, and a vector describing residuals. The solution vector yields age‐dependent maximum somatic growth rates of herring larvae up to an age of 41 days with sizes ranging from 10 to 25 mm. The observed environmental temperature in which larvae dwelled was relatively uniform. Therefore, measured increment width was individually used to determine daily growth from any single larva in relation to their potential maximum growth under optimal feeding conditions. The results are discussed with respect to the spatial and temporal variability of larval occurrence. Finally, an analysis of error estimation of the larval growth characteristics is presented.  相似文献   

19.
《Fisheries Research》2007,87(2-3):99-104
A bow-mounted surface pushnet and an obliquely towed plankton net were compared to evaluate gear efficiency and effectiveness in collecting larval fishes under daytime and nighttime conditions. The diadromous species targeted were striped bass Morone saxatilis, white perch, Morone americana, and river herring Alosa sp. We sampled the lower Roanoke River, North Carolina, from March through June of 2002 and 2003. Striped bass, white perch and river herring represented over 90% of the larvae collected during the study period. Mean larval densities (number/100 m3) were 63.4 for striped bass, 26.4 for river herring, and 17.7 for white perch. Striped bass larval densities were significantly higher in the surface pushnet for both years (P ≤ 0.05). In 2002, white perch mean larval density was significantly higher at night in the surface pushnet samples, but in 2003 there were no differences between day and night samples. River herring mean densities were significantly higher in the surface pushnets for both years, but showed no clear patterns between day and night samples. Larger larvae were consistently collected in the surface pushnets for all species. Overall, the surface pushnet was easier to operate. The pushnet was mounted on the bow of a small jon boat and required less specialized gear and fewer personnel than oblique sampling. The method also allows for sampling in shallow water or vegetated habitats. Because larvae were significantly larger in the surface samples, using surface pushnets may not allow for detection of the smaller-sized larvae therefore underestimating the abundance of smaller fish. Depending on the question being asked, we recommend that sampling programs should use both gear types to reduce any gear biases.  相似文献   

20.
Following the 1989 MV Exxon Valdez oil spill (EVOS) and subsequent herring population collapse in Alaska's Prince William Sound (PWS), the Pacific herring (Clupea pallasii) fishery was closed. In the 25 yr since EVOS, herring and several herring‐dependent marine bird species have failed to reach pre‐spill population levels. One hypothesis is that intense predation pressure may be inhibiting herring recovery. To inform herring modeling efforts, this study estimated marine bird consumption of juvenile and adult herring in PWS for 10 winters over an 18‐yr period (1989–90 through 2006–2007). Total estimated herring consumption by wintering marine birds averaged 2409 ± 950 t, indicating that avian consumption represents a substantial and inter‐annually variable source of herring mortality. Common murre (Uria aalge) consumed the greatest portion (16–80%) of herring in all years among marine bird species. Juvenile herring biomass consumed annually by common murre was greater than murre consumption of adult herring biomass. Time lag analyses showed that marine bird consumption of adult herring is negatively correlated with the amount of herring spawn observed in subsequent years, but such effects were not observed more than 2 yr. Our models indicate that during years in which herring recruitment is low or bird populations are particularly large, marine birds can consume up to 10% of the annual adult herring biomass. Our results highlight the importance of herring to wintering PWS birds. We propose that future management of herring stocks seeks to reduce negative impacts on marine birds that prey on herring.  相似文献   

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