Abundance Of Fish Larvae Research Articles

Interaction between spawning habitat and coastally steered circulation regulate larval fish retention in a large shallow temperate bay

Larval retention plays a fundamental role in the persistence of coastal fish assemblages. Here, we examine larval fish distribution and abundance patterns in Palma Bay, a large (∼20 km) wind-driven microtidal bay in the southern coast of Mallorca (Spain, NW Mediterranean Sea). Larval fish assemblage structure in the bay were analyzed during July 2010 and interpreted in the context of the observed circulation patterns, adult habitat distribution and spawning traits. Acoustic Doppler Current Profiler (ADCP) observations showed the presence of retentive flow patterns in the middle of the bay enhancing local larval accumulation and self-recruitment. In consequence, larval abundances were higher in this central part of the bay (∼40 m depth, mean abundance 607.6 ± 383 ind. 10 m−2) than along the coastal fringe (<35 m 113.7 ± 91 ind. 10 m−2). Also, a multivariate predictive approach based on Redundancy Analysis (RDA) revealed differences between the larval fish assemblages in areas inside the bay, constituted by small pelagic and benthopelagic taxa (gobids, Chromis chromis and Serranus hepatus) and offshore larvae, mostly from meso and large pelagic fish. These larval fish assemblages were structured according to depth variations and zooplankton abundance, and remained relatively unmixed because of the circulation patterns in the mouth of the bay that uncouple its dynamics from alongshelf circulation. Even larvae of typically pelagic species that spawn close to the coast (Sardinella aurita, Auxis rochei) were associated with the retentive effect of the bay. Our study highlights the important role of coastal bays in the regulation of coastal fish population dynamics and as hotspots for the maintenance of diversity in the Mediterranean Sea.

Suprabenthic species distributions relative to small-scale bathymetric features along the Virginia coast, USA

This investigation explored relationships between suprabenthic community composition and fine-scale differences among bathymetric features in the shallow ocean waters and the surf zone off an eastern North America barrier island. Suprabenthic sled collections from the surf to 4 km offshore of Assateague Island, Virginia in June of 2008 and 2009 provide the first detailed analysis of the suprabenthic community of the first 30 cm above the sea floor along the Atlantic coast of the United States. Multidimensional scaling (MDS) revealed discrete assemblages of suprabenthic fauna associated with specific bathymetric features (surf zone, inshore flat, an 11–13 m deep trough, and an adjacent ridge). Virtually all abundant taxa showed significantly different abundances between these four zones (ANOVA). The densities of key taxa between years differed, but their affinities for specific zones were evident in both years. The near-shore flat had the highest abundances of crab and fish larvae, suggesting that this area may serve an underappreciated role as nursery habitat for both estuarine and coastal ocean species. The trough was notable for its aggregations of large crustaceans, the mysid Neomysis americana and shrimp Crangon septemspinosa, that are probably an important link in benthopelagic trophic transfer from detritus to fishes. Compared to coastal collections from the eastern Atlantic, the subtidal suprabenthos collected at Assateague showed an unusually large variety and abundance of anomuran crustaceans and a paucity of gammarid amphipods.

The spatial pattern of larval fish assemblages in the lower reach of the Yangtze River: potential influences of river–lake connectivity and tidal intrusion

Landscape pattern plays an important role in structuring of larval fish assemblages in large river basins. The lower reach of the Yangtze River includes the river section from the mouth of Poyang Lake, the largest freshwater lake in China, downward to the estuary. We hypothesized that river-lake connectivity at the upstream portion and tidal intrusion at the downstream portion are significant drivers of larval fish assemblages. Larval fish were collected monthly from April 2012 through September 2013 in three locations at Anqing (AQ), Nanjing (NJ), and Jingjiang (JJ). Fifty-six taxa of larval fish were identified with 52 of them determined of species. Larval fish were highly abundant from April through August; the number of species and the abundance were much higher at AQ than at NJ and JJ; the bloom of larval fish at JJ tended to be later than at NJ and AQ. We suggest that the larger number of species and higher abundance of larval fish at AQ reflect the effects of the connectivity of Poyang Lake with the river upstream of AQ, and the delayed bloom of larval fish and the occurrence of estuarine species at JJ reflect the influences of tidal intrusion from the estuary.

Productivity and biomass of fishes in the California Current Large Marine Ecosystem: Comparison of fishery-dependent and -independent time series

Commercial landings are often the only data available to assess the status of marine fish populations, but may reflect economics, technology and management policy in addition to stock size. In the California Current Large Marine Ecosystem (CCLME), the availability of CalCOFI ichthyoplankton data enabled us to compare commercial landings with a fishery-independent time series from 1951 to 2011. Fishery landings for the CCLME generally increased over this period, peaking about 1990 and displaying no clear subsequent trend. However, the abundance of ichthyoplankton in the southern CCLME has declined by ~70% since about 1970, based on the decline of taxa with cool-water affinities, apparently related to ocean warming and reduced productivity, and of mesopelagic taxa since the 1990s in response to declining midwater oxygen concentrations. These results highlight the importance of sustained fishery-independent time series at a time of secular climate change.Calibration of the larval fish abundance time series with stock assessments and acoustic/trawl surveys provided a proxy time series of spawning stock biomass for epi- and mesopelagic planktivores since 1951. We estimate that mesopelagic fishes comprised ~83% of the biomass of plankton-feeding fishes in the southern CCLME, but their prey consumption appears approximately equivalent to that of epipelagic planktivores because of the greater metabolic requirements of epipelagic fishes. The “wasp-waist” paradigm for eastern boundary currents needs to be re-assessed based on revised assessments for the abundance of mesopelagic fishes.

Composition and structure of the larval fish community in the NW Iberian upwelling system during the winter mixing period

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 533:245-260 (2015) - DOI: https://doi.org/10.3354/meps11348 Composition and structure of the larval fish community in the NW Iberian upwelling system during the winter mixing period J. M. Rodriguez1,*, A. Cabrero2, J. Gago2, A. Garcia3, R. Laiz-Carrion3, C. Piñeiro2, F. Saborido-Rey4 1Instituto Español de Oceanografía, Centro Oceanográfico da Gijón 33212, Gijón, Spain 2Instituto Español de Oceanografía, Centro Oceanográfico de Vigo 36390, Vigo, Spain 3Instituto Español de Oceanografía, Centro Oceanográfico de Málaga, 29640 Fuengirola, Málaga, Spain 4Instituto de Investigaciones Marinas (CSIC), Eduardo Cabello 6, 36208 Vigo, Spain *Corresponding author: j.m.rodriguez@gi.ieo.es ABSTRACT: The composition and structure of the larval fish community (LFC) in the NW Iberian upwelling system in late winter 2012 were examined, and the influence of abiotic and biotic factors on the horizontal distribution of fish larvae and on the horizontal structure of the LFC was investigated. The LFC, composed of 62 taxa (59 species and 3 genera) in 28 families, was dominated by Micromesistius poutassou followed by Scomber scombrus, Merluccius merluccius and Maurolicus muelleri. Multivariate analyses identified depth, sea surface temperature, geostrophic velocity and mesozooplankton biomass as the environmental factors involved in explaining variability in the LFC parameters (larval fish abundance, species richness and diversity) and revealed that the LFC was structured into coastal and slope larval fish assemblages. The main factor defining these assemblages was depth. However, the unusual coastal downwelling that occurred during the study would have participated in creating them and in maintaining assemblage boundaries, so that the importance of depth to the cross-shelf structuring of the LFC may have been overestimated. Our results suggest that larval fish assemblages in regions of coastal upwelling are driven by coastal downwelling during the winter mixing period and support the idea that fish larvae act as short-term (~10 d) biological tracers of the hydrography of the region during that period. KEY WORDS: NW Iberian upwelling system · Hydrography · Winter mixing period · Downwelling · Ichthyoplankton · Larval fish community Full text in pdf format PreviousNextCite this article as: Rodriguez JM, Cabrero A, Gago J, Garcia A, Laiz-Carrion R, Piñeiro C, Saborido-Rey F (2015) Composition and structure of the larval fish community in the NW Iberian upwelling system during the winter mixing period. Mar Ecol Prog Ser 533:245-260. https://doi.org/10.3354/meps11348 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 533. Online publication date: August 06, 2015 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2015 Inter-Research.

Influence of the aquatic vegetation landscape on larval fish abundance

Abstract Aquatic vegetation (AV) is an important component of aquatic system, affecting habitat carrying capacity and fish productivity. By modulating habitat complexity, AV has the potential to influence the early ontogenetic stages of many fish species. However, understanding how variations in AV abundance influence fish distribution and abundance at the landscape scale of freshwater ecosystems is a considerable challenge due to the difficulty of collecting the high-resolution data needed for such analyses. We used yellow perch ( Perca flavescens ) as a biological model to test the hypothesis that larval fish abundance is positively related to a AV-rich landscape. Combining seven years of extensive larval sampling and satellite imagery, our results suggest that fish larvae tend to be associated with AV habitats after hatching. Based on zero-inflated binomial models, the probability of observing perch larvae increased from approximately 20% in low AV habitats to nearly 100% in dense AV habitats (pseudo- R 2 = 0.54). Our results also show that the probability of observing yellow perch larvae was lower during years of low water level and low AV biomass, likely limiting the availability of proper spawning or nursery habitats for fish. Furthermore, we demonstrate that larvae use both new AV as well as vegetative debris from the previous year that persisted through the winter. In agreement with a growing literature, our study gives additional support to the idea that AV plays a key role in freshwater fish recruitment.

Abundance and diversity of fish larval assemblages in Iranian waters of the Oman Sea

A survey on the abundance and diversity of fish larvae along the Iranian waters of the Oman Sea, extending from Hormuz Strait to Gowatr Bay, was carried out in 2009 (before and post monsoon). Fish larva were collected by a Bongo net (300 µ mesh size) and temperature, salinity, dissolved oxygen, pH, chlorophyll-a, clarity, nitrate, nitrite, silicate and sulfate by oceanic data recorder (CTD) and Rosette oceanography instrument were measured. In total, 26 fish families were identified and their abundance calculated as 768 individuals per m 2 . In pre-monsoon, 9 families were identified with Pomacentridae as dominant taxon. But in post-monsoon, 23 families were identified in which Myctophidae was dominant. The Shannon index was calculated as 0.583 ± 0.31 in pre-monsoon and 0.865 ± 0.73 in post-monsoon. The result of Principle Component Analysis (PCA) revealed a higher diversity among ichthyoplankton in post-monsoon compared to that of pre-monsoon. The abundance of fish larva was correlated with chlorophyll-a in post-monsoon, whereas samples from pre-monsoon were more positively correlated with in nutrients.

Three-dimensional distribution of larval fish habitats in the shallow oxygen minimum zone in the eastern tropical Pacific Ocean off Mexico

Three-dimensional distribution of larval fish habitats was analyzed, from the upper limit of the shallow oxygen minimum zone (~0.2mL/L) to the sea surface, in the eastern tropical Pacific Ocean off Mexico in February 2010. The upper limit rises from ~250m depth in the entrance of the Gulf of California to ~80m depth off Cabo Corrientes. Three larval fish habitats were defined statistically: (i) a Gulf of California habitat dominated by Anchoa spp. larvae (epipelagic species), constrained to the oxygenated surface layer (>3.5mL/L) in and above the thermocline (~60m depth), and separated by a salinity front from the Tropical Pacific habitat; (ii) a Tropical Pacific habitat, dominated by Vinciguerria lucetia larvae (mesopelagic species), located throughout the sampled water column, but with the highest abundance in the oxygenated upper layer above the thermocline; (iii) an Oxygen Minimum habitat defined mostly below the thermocline in hypoxic (<1mL/L; ~70m depth) and anoxic (<0.2mL/L; ~80m depth) water off Cabo Corrientes. This subsurface hypoxic habitat had the highest species richness and larval abundance, with dominance of Bregmaceros bathymaster, an endemic neritic pelagic species; which was an unexpected result. This may be associated with the shoaling of the upper limit of the shallow oxygen minimum zone near the coast, a result of the strong costal upwelling detected by the Bakun Index. In this region of strong and semi-continuous coastal upwelling in the eastern tropical Pacific off Mexico, the shallow hypoxic water does not have dramatic effects on the total larval fish abundance but appears to affect species composition.

The impact of environmental variability on Atlantic mackerel Scomber scombrus larval abundance to the west of the British Isles

The value of the Continuous Plankton Recorder (CPR) fish larvae dataset, with its extensive spatio-temporal coverage, has been recently demonstrated with studies on long-term changes over decadal scales in the abundance and distribution of fish larvae in relation to physical and biological factors in the North Sea. We used a similar approach in the west and southwest area of the UK shelf and applied a principal component analysis (PCA) using 7 biotic and abiotic parameters, combined with Hierarchical Cluster Analysis (HCA), to investigate the impact of environmental changes in the west and southwest area of the UK shelf on mackerel larvae during the period 1960–2004. The analysis revealed 3 main periods of time (1960–1968; 1969–1994; 1995–2004) reflecting 3 different ecosystem states. The results suggest a transition from an ecosystem characterized by low temperature, high salinity, high abundances of zooplankton and the larger phytoplankton groups, to a system characterized by higher temperature, lower salinities, lower abundances of zooplankton and larger phytoplankton and higher abundances of the small phytoplankton species. Analysis revealed a very weak positive correlation between the Second principal component and mackerel larvae yearly abundance, attributed to the North Atlantic Oscillation (NAO). The results presented here are in broad accord with recent investigations that link climatic variability and dynamics of mackerel reproduction. However, the growing body of literature that documents statistical correlations between environment and mackerel needs to be supplemented by local process studies, to gain more insight and to be able to predict mackerel response to climate change scenarios. Utilising the strength of the CPR dataset, namely its unique temporal coverage, in an analysis where other data (such as egg surveys) are drawn in to compensate for the spatial issues could prove to be the way forward.

Is ectoparasite burden related to host density? Evidence from nearshore fish larvae off the coast of central Chile

Variations in parasite populations may be temporal and/or spatial and can occur in relation to environmental factors. However, such changes may also occur due to differences in host population density, which is one of the main factors that affect the abundance of directly transmitted parasites. Fish larvae and their ectoparasites were collected via ichthyoplankton samplings during a 3-year survey near the coast of central Chile. To estimate the variations in ectoparasite abundance that occurred with fluctuations in host density, the prevalence and intensity of ectoparasites (copepods and isopods) were calculated and compared with the density (i.e., the larval fish abundance standardized to 1,000 m−3) of six species of nearshore fish larvae that belonged to the families Gobiesocidae, Labrisomidae and Tripterygiidae. Copepods (Penellidae and Caligidae) and isopods (Cryptoniscidae) were found to be parasitizing the fish larvae. Pennellid copepods were the most prevalent ectoparasite, and the clingfish Gobiesox marmoratus (Gobiesocidae) was the most parasitized fish species (12.81 %). The individual burdens of pennellid, caligid and isopod ectoparasites failed to exhibit any correlation with the larval densities of four fish species (i.e., Auchenionchus crinitus, Auchenionchus microcirrhis, Sicyases sanguineus and Helcogrammoides chilensis). Nonetheless, the prevalence and intensity of the pennellid copepods exhibited a significant and positive correlation with the density of a gobisesocid species. In contrast, the prevalence of pennellid copepods (5.10 %) exhibited a significant but negative correlation with the density of tripterygid fish. Ectoparasite abundance is a result of a species-specific relationship with their hosts, but the evidence found suggests no correlation between ectoparasite burden and host density in larval fishes from coastal environments.

Environmental factors affecting larval fish community in the salt marsh area of Guadiana estuary (Algarve, Portugal)

Salt marsh areas in the Guadiana estuary are important nursery sites for many fish species of commercial and recreational value. More effective protection measures should be adopted as the area is highly affected by anthropogenic and natural threats. Studying larval fish communities in these impacted nursery areas will be relevant to the management of local ecosystems and to larval fish ecology in general. Spatial and seasonal distribution and the effect of environmental factors on the larval fish community of this ecosystem were studied for one year (April 2010 to March 2011). Larvae were sampled monthly in parallel with phytoplankton and zooplankton. Hydrological data and physical parameters were monitored. A decision tree model was used to assess the influence of environmental factors on the larval fish community. A total of 130 larvae and 1171 eggs were caught. Diplodus sargus, Sardina pilchardus, and Pomatoschistus microps were the most abundant larval fish species. The peaks of fish larvae abundance occurred in March and April. The output of the model demonstrates that the abundance of larval fish is determined by the abundance of eggs, zooplanktonic food, and water flood and flow. This study shows the importance of the Guadiana salt marsh as an area for fish nursery and highlights the need for conservation of this area.

Trophic structure of the pelagic food web in the East China Sea.

Trophic structure and trophic transfer efficiency are among the most fundamental characteristics of an ecosystem. They characterize the transfer of nutrient and energy and are crucial in estimating the yield of harvestable biomass. In this study, we investigated the regulation of trophic structure (phytoplankton, zooplankton, and larval fish abundance) and biomass ratio of zooplankton to phytoplankton (as an indicator of transfer efficiency) in the East China Sea, one of the largest marginal seas in the world and an important fishing ground. Theresults showed that when sea surface temperature was below 25°C, temperature co-acted with resource availability (zooplankton for larval fish and phytoplankton for zooplankton) in determining the trophic structure. When sea surface temperature was above 25°C, resource availability dominated the regulation of trophic structure. Biomass ratio of zooplankton to phytoplankton decreased with increasing phosphate concentration. Our study suggested that the trophic structure of the East China Sea might be controlled by bottom-up processes, and this control is mediated by temperature.

Oceanographic scenario and fish larval distribution off Guinea-Bissau (north-west Africa)

This paper describes the hydrography and the larval fish assemblage of Guinea Bissau waters, and analyses the spatial distribution of the main families in relation to the oceanographic features of the area. Data were obtained during an oceanographic survey, undertaken between October and November 2008. In addition to 98 demersal fishing hauls, a total of 33 stations, located between 20 and 1000 m depth, were sampled for hydrography and ichthyoplankton. Data showed that Guinea-Bissauan surface waters are characterized by a strong thermohaline front that flows parallel to the bathymetry of the area. Warm surface waters (SST &gt; 29°C) occupy the inner shelf, and colder (SST &lt; 26°C), chlorophyll-a-rich waters take over the shelf break. Continental runoff seems responsible for the low salinity of the inner-shelf waters whereas the colder types bear thermohaline features typical of tropical Atlantic waters. These features define a scenario which favours the development of fish early life stages, reflected in the high abundance and diversity of fish larvae recorded. A total of 84 taxa of fish larvae were identified. Only the family Clupeidae accounted for 54.8% of the sampled larvae. Other important families were Carangidae (8.8%), Sparidae (8.4%) and Myctophidae (5.9%).

Abundance and diversity of reef fish larvae in Mabahiss Bay, on the Egyptian Red Sea coast

Abundance and diversity of reef fish larvae in Mabahiss Bay, on the Egyptian Red Sea coast

Winds vs. tides: factors ruling the recruitment of larval and juvenile fishes into a micro-tidal and shallow choked lagoon (Argentina)

Choked lagoons (like Mar Chiquita, Argentina) are influenced by local winds because the inlet channel acts as a dynamic filter which reduce tidal fluctuations. Previous studies showed that the effects of onshore winds appear to prevail over daily-tide cycles (ebb, flood) in the recruitment of young fishes into this micro-tidal and shallow estuary. Therefore, the aim of this study was to evaluate the recruitment success of larval and juvenile fishes from the sea into this choked lagoon related to the conjunction of global (lunar-tide cycle) and local (wind regime) processes. Weekly fish sampling was conducted in Mar Chiquita’s inlet channel and its adjacent surf zone from early spring to late summer. For each fish developmental stage (i.e. larval and juvenile), a multiple-hypothesis model approach was adopted by fitting generalized linear models (GLM) with the abundance of fishes as the response variable and possible combinations of seasons, sites, water parameters and the wind effect as explanatory variables. The abundances of fish larvae and juveniles were mainly affected by wind regimen and seasonal changes according to the best model selected. Larval and juvenile fishes were more abundant at summer months during strong (> 10 m · s−1) onshore wind episodes. The lunar-tide cycle effect was not relevant for the success of fish recruitment. Despite its seasonal regularity, wind is a much more unpredictable factor than tides, and therefore, it is remarkable to note the implications that have for fishes the recruitment towards an estuarine system depending on such unpredictable force. The importance of the fish nursery role of the coastal area close to the mouth of an estuary with this environmental feature is discussed.

Seasonal variations in diversity and abundance of surface ichthyoplankton in the northern South China Sea

The objective of this study was to investigate the seasonal variations of ichthyoplankton diversity and abundance in the northern South China Sea based on the data collected during summer, winter and spring. In total, 95 taxa of larval fishes were identified. The greatest number of species was recorded in spring, followed by summer and winter. The number of species was distributed mainly in the coastal waters from the east of Leizhou Peninsula to the southeast of Hainan Island during the surveyed periods of summer and spring, but in the offshore waters during winter. The abundance of larval fish was lowest in winter, increased in spring, and reached the maximum in summer. High abundance of larval fish was generally restricted to coastal waters with the isobaths less than 50 m. Seasonal variations of larval fish richness, abundance and diversity index were significant (P<0.001). Carangidae was the most common and abundant taxon in summer and winter, while Sardinella sp., Thrissa mystax and Leiognathus sp. were dominant in spring. High diversity and abundance of larval fish might be attributed to increased temperature and coastal upwelling in spring and summer.

Abundance and Diversity of Reef Fish Larvae in Mabahiss Bay , on the Egyptian Red Sea Coast

Abundance and Diversity of Reef Fish Larvae in Mabahiss Bay , on the Egyptian Red Sea Coast

Larval fish variability in response to oceanographic features in a nearshore nursery area.

The influence of oceanographic features on ichthyoplankton assemblages in the warm temperate nearshore region of Algoa Bay, South Africa, was assessed. The nearshore ichthyoplankton comprised 88 taxa from 34 families. Samples were collected at six stations between August 2010 and July 2012 using a plankton ring net of 750 mm diameter and 500 µm mesh aperture. The majority of larvae collected were in a preflexion stage, indicating the potential importance of the nearshore for newly hatched larvae. Engraulidae dominated the catch (38·4%), followed by Cynoglossidae (28·1%) and Sparidae (8·4%). Larval fish abundance was highest during austral spring and summer (September to February). Unique patterns in responses of each dominant fish species to oceanographic features in the nearshore indicate the sensitivity of the early developmental stage to environmental variables. Using generalized linear models, ichthyoplankton abundance responded positively to upwelling and when warm water plumes originating from an Agulhas Current meander entered Algoa Bay. Highest abundances of Engraulis encrasicolus and Sardinops sagax were observed during Agulhas Plume intrusions into Algoa Bay. When a mixed and stratified water column persisted in the nearshore region of Algoa Bay, larval fish abundance decreased. The nearshore region of Algoa Bay appears to serve as a favourable environment for the accumulation of ichthyoplankton.

The role of internal waves in larval fish interactions with potential predators and prey

Tidally driven internal wave packets in coastal environments have the potential to influence patchiness of larval fishes, prey, and gelatinous predators. We used the In Situ Ichthyoplankton Imaging System (ISIIS) to synoptically sample larval fishes, copepods, and planktonic predators (ctenophores, hydromedusae, chaetognaths, and polychaetes) across these predictable features in the summer near Stellwagen Bank, Massachusetts, USA. Full water column profiles and fixed depth transects (∼10m depth) were used to quantify vertical and horizontal components of the fish and invertebrate distributions during stable and vertically mixed conditions associated with tidally generated internal waves. Larval fishes, consisting mostly of Urophycis spp., Merluccius bilinearis, and Labridae, were concentrated near the surface, with larger sizes generally occupying greater depths. During stable water column conditions, copepods formed a near surface thin layer several meters above the chlorophyll-a maximum that was absent when internal waves were propagating. In contrast, ctenophores and other predators were much more abundant at depth, but concentrations near 10m increased immediately after the internal hydraulic jump mixed the water column. During the propagation of internal waves, the fine-scale abundance of larval fishes was more correlated with the abundance of gelatinous predators and less correlated with copepods compared to the stable conditions. Vertical oscillations caused by the internal hydraulic jump can disperse patches of zooplankton and force surface dwelling larval fishes into deeper water where probability of predator contact is increased, creating conditions potentially less favorable for larval fish growth and survival on short time scales.

Unravelling the Gordian knot! Key processes impacting overwintering larval survival and growth: A North Sea herring case study

Unraveling the key processes affecting marine fish recruitment will ultimately require a combination of field, laboratory and modelling studies. We combined analyzes of long-term (30-year) field data on larval fish abundance, distribution and length, and biophysical model simulations of different levels of complexity to identify processes impacting the survival and growth of autumn- and winter-spawned Atlantic herring (Clupea harengus) larvae. Field survey data revealed interannual changes in intensity of utilization of the five major spawning grounds (Orkney/Shetland, Buchan, Banks north, Banks south, and Downs) as well as spatio-temporal variability in the length and abundance of overwintered larvae. The mean length of larvae captured in post-winter surveys was negatively correlated to the proportion of larvae from the southern-most (Downs) winter-spawning component. Furthermore, the mean length of larvae originating from all spawning components has decreased since 1990 suggesting ecosystem-wide changes impacting larval growth potential, most likely due to changes in prey fields. A simple biophysical model assuming temperature-dependent growth and constant mortality underestimated larval growth rates suggesting that larval mortality rates steeply declined with increasing size and/or age during winter as no match with field data could be obtained. In contrast better agreement was found between observed and modelled post-winter abundance for larvae originating from four spawning components when a more complex, physiological-based foraging and growth model was employed using a suite of potential prey field and size-based mortality scenarios. Nonetheless, agreement between field and model-derived estimates was poor for larvae originating from the winter-spawned Downs component. In North Sea herring, the dominant processes impacting larval growth and survival appear to have shifted in time and space highlighting how environmental forcing, ecosystem state and other factors can form a Gordian knot of marine fish recruitment processes. We highlight gaps in process knowledge and recommend specific field, laboratory and modelling studies which, in our opinion, are most likely to unravel the dominant processes and advance predictive capacity of the environmental regulation of recruitment in autumn and winter-spawned fishes in temperate areas such as herring in the North Sea.