Next Article in Journal
The Effect of Temporal and Environmental Conditions on Catch Rates of the Narrow-Barred Spanish Mackerel Setnet Fishery in Khanh Hoa Province, Vietnam
Previous Article in Journal
Design and Performance Evaluation of a Feed Distribution Device in the Small-Scale Pneumatic Conveying Feeder for Recirculating Aquaculture Systems
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Fishes
Volume 10
Issue 6
10.3390/fishes10060256
fishes-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Diet Composition of Twaite Shad, Alosa fallax (Lacépède, 1803), During the Spawning Migration to the Curonian Lagoon (Lithuania)

by
Edoardo Nobili
1,
Harry Gorfine
2,
Eglė Jakubavičiūtė
1,
Žilvinas Pūtys
1,* and
Linas Ložys
1
1
State Scientific Research Institute Nature Research Centre, Akademijos St. 2, 08412 Vilnius, Lithuania
2
Victorian Fisheries Authority, Queenscliff Centre, 2A Bellarine Hwy., Queenscliff, VIC 3225, Australia
*
Author to whom correspondence should be addressed.
Fishes 2025, 10(6), 256; https://doi.org/10.3390/fishes10060256
Submission received: 25 April 2025 / Revised: 26 May 2025 / Accepted: 27 May 2025 / Published: 1 June 2025
(This article belongs to the Section Biology and Ecology)
Browse Figures
Versions Notes

Abstract

The nutritional needs of anadromous fish species must be met for successful annual spawning migration and reproduction. Despite its widespread distribution throughout Europe, little is known about the composition of the twaite shad, Alosa fallax, diet in freshwater ecosystems. To redress this, we studied the composition of stomach contents extracted from 287 A. fallax sampled during their spawning migration from the Baltic Sea to the Curonian Lagoon (Lithuania). We found that the diet comprised 32 types of prey, with Insecta (unknown Order), Chironomidae and Daphniidae being the most prevalent taxonomic categories consumed. Our analyses revealed significant differences in the abundance of prey categories (Chironomidae, Insecta—unknown order, and Mysidae) among several size groups of A. fallax, associated with stage of maturity inferred from body length. Despite this being a spawning aggregation, juveniles were also present among the A. fallax we collected. The results imply that feeding behavior and morphometry may be responsible for the differences observed, and further investigation of this topic is warranted.
Keywords:
feeding ecology; foraging behavior; coastal ecosystem; Stomach Content Analysis; diet
Key Contribution: This study presents the first comprehensive investigation into the diet composition of endangered Alosa fallax at a known spawning area in a freshwater coastal lagoon, addressing a significant knowledge gap in the trophic ecology of this species in the Baltic Sea region.

1. Introduction

Investigation of the diet of fish provides knowledge about their nutritional needs, the role that food plays in ontogenesis, information about the availability of food resources in the environment, insights into food preferences and information about interactions with the other organisms [1,2,3]. Dietary studies are also crucial for providing valuable information about how interactions between organisms and their environment contribute to ecosystem functioning and mandate specific management arrangements [4].
Importantly, this knowledge contributes toward developing species and ecosystem management strategies to promote the sustainable use and conservation of commercially important fisheries [4,5,6]. Dietary studies can be conducted via Stomach Content Analysis (SCA), which enables taxonomic resolution of the diet [4] by identifying and quantifying food items to assist in drawing inferences about food preferences [7].
Twaite shad, Alosa fallax (Lacépède, 1803), is a fish of the Clupeidae family with an extensive distribution throughout Europe [8]. Since 2010, its status has been of ‘least concern’ on the IUCN Red List [9], and it is classified as a focal species under the EU Habitats Directive [10]. Alosa fallax is an anadromous fish with an egg-laying season beginning in spring in the Mediterranean region, whereas in the northern European regions, it commences around the beginning of June [11].
Alosa fallax is predominantly ichthyophagous [12], with adults feeding on crustaceans (i.e., euphausiids, mysids and isopods) and small fish. When young, they feed mainly on invertebrates, especially estuarine zooplankton, as well as the fry of sardines, herrings, sprats, anchovies and gobies [11,13,14,15,16]. Moreover, plant material and eggs (from fish or amphibians) have been found in the stomachs of A. fallax [17].
In the first half of the 20th century, A. fallax was one of the most abundant anadromous fish in the Curonian Lagoon [18]. During the breeding season, this species used to migrate from the Baltic Sea through the Lagoon to the Nemunas River. However, the species became almost locally extinct and was strictly protected by national legislation. Since its recovery in the mid-1990s, it no longer migrates to the Nemunas River to spawn, but instead spawns in the open water areas of the freshwater Curonian Lagoon near the Nemunas delta, and on these occasions, several researchers have been able to capture specimens for their studies [18,19,20]. In recent decades (past 20–30 years), the abundance has increased to the extent that even a commercial fishery (as a bycatch) for A. fallax is allowed in the Curonian Lagoon.
The diet of A. fallax during spawning in estuaries remains poorly understood, especially in Lithuania. Until now, only a few studies have reported the feeding and diet of adult A. fallax during the pre-spawning phase of their annual reproductive period. In freshwater, stomach contents examined in previous studies have contained allochthonous plant material, plastics and different parts of insects in various phases of life history (eclosion, larva, pupa, nymph and adult), indicating that A. fallax had been feeding on relatively large particles in the drift or at the water surface [17,21,22].
The aim of this study of A. fallax in the Curonian Lagoon was to provide (1) qualitative and quantitative analyses of the diet composition during pre-spawning, with as much taxonomic precision as practicable, and (2) an analysis of differences in diet by size group. It is anticipated that the results will contribute to effective management and conservation of this species, which is protected by the EU Habitats Directive.

2. Materials and Methods

2.1. Sampling Site and Fish Samples

The Curonian Lagoon is a coastal freshwater body separated from the brackish Baltic Sea by a narrow sandy spit, comprising a series of exposed and forest-covered dunes. At its northern end, the Lagoon is connected to the Baltic Sea by the navigable Klaipėda Strait. The east coast of the Lagoon is low, forested wetland, part of which forms the Nemunas River delta.
Sampling for A. fallax was undertaken in the Curonian Lagoon during June 2022, at a location known for aggregations of this species during its short annual spawning season. Samples were collected near the coast of Ventė Cape (55°21′24″ N, 21°10′5″ E) using three trapnets with the following mesh size from knot to knot: 30 mm for the leader (length 100 m), 30 mm for the heart and 20 mm for the cod end (Figure 1). The trapnets were set in the evening and then, during the following morning, they were checked and entrapped fish were removed. The catch per unit effort (one trapnet per night) in numbers was estimated to average 58.8 specimens of A. fallax. The sampling was repeated 6 times. The fish collected were killed by a forceful and accurate blow to the head with a blunt wooden instrument.
Biological measurements (Total Length (TL), Standard Length (SL), Weight (W) and Weight without gonads (W-) [23]) were made immediately upon collection, and then the fish were subsequently frozen and stored at −20 °C.

2.2. Sampling Matrix and Preparation

To investigate differences in diet across length groups, samples up to 25 females and 25 males were randomly collected in each 5 cm length (TL) group. In total, 287 fish (total length range, mean ± standard deviation (SD): 16–48 cm; mean: 32.77 ± 7.53; weight range: 42–774 g; mean: 320.1 ± 179.44) were sampled and, for each sample, the stomach contents were analyzed. Based on the length–frequency distribution in 5 cm classes, the A. fallax samples were divided into 3 length–size groups (TL, cm) for the statistical analysis of differences in dietary composition: from 16 to 27 cm (small, n = 56, 5 males, 7 females, 44 juveniles), from 28 to 37 cm (medium, n = 137, 92 males, 45 females) and from 38 to 48 cm (large, n = 94, 38 males, 56 females).
The fish were dissected (every internal organ was removed separately using scissors, forceps and scalpels), and their stomachs were removed and preserved in a solution of 70% alcohol and 30% water for subsequent dietary analysis. Prey items were identified to the lowest taxonomic level possible under a stereomicroscope. To ensure precision in quantitative and qualitative analysis of stomach fullness, the stomach contents were weighed to the nearest gram and the degree of fullness was classified on a scale of 0 to 4 based on visual estimation. For qualitative analysis of stomach fullness, the range of proposed categories was set from 0 to 4, where 0 = empty, 1 = almost empty, 2 = ½ full, 3 = ¾ full and 4 = full stomach for different size groups. Prey items were allocated to diet categories as follows: aquatic invertebrates, terrestrial invertebrates and other prey items. In tabulation of the results, they were classified a far as practicable into the following taxonomic categories: Order, Family. Food items that were too damaged to be classified were assigned as “Unidentified”. In the category “Insecta”, some of the elements analyzed could not be identified to a specific order (unknown Order). From taxonomic reference images and comparisons with parts already identified with certainty, e.g., Insecta, Crustacea, it was possible to identify different parts of the cuticle and recognize the stage of development, but it was impossible to recognize the order to which they belonged [24,25,26,27,28,29]. The abundance of plant materials was not quantified as it was impractical to count individual items, but the number of stomachs in which they appeared was noted. Fish with empty stomachs were excluded from diet analyses (65 in total). For quantitative analysis of stomach fullness, the degree of stomach fullness (f) was calculated for each fish as follows [30]:
f = (Ws/W) × 100
Ws = total stomach content wet weight (g);
W = fish wet weight (g).
Fish prey were identified from otoliths using reference material and published guides [31,32]. Animal prey items were identified to the lowest taxonomic level possible.
For the description of the diet, data were analyzed in terms of relative abundance of prey (Ai) [33]:
Ai = (Si/St) × 100
Si = total number of prey I;
St = total number of all prey items.
The frequency of occurrence of prey was also calculated [13]:
(Fi = (Ni/N) × 100
Ni = number of fishes with prey i in their stomach;
N = total number of fishes with stomach contents of any kind.
Due to non-normality of the data despite transformation, the non-parametric Kruskal–Wallis test was applied (p-value < 0.05) to evaluate the differences in diet between different size groups. Statistical analyses were performed using the statistical software Past4 and R (v4.1.2; R core Team 2021). The Costello graphical method [34] modified by Amundsen et al. [35] was used to visualize the diet patterns. The diet was characterized by plotting weight percentage (%Wf = weight of each taxonomic group as a percentage of the mass of total stomach contents) against frequency of occurrence (%F = 100 × [number of stomachs where prey item i was observed]/[number of stomachs containing food]) of the prey taxa for the three different size groups of A. fallax: Small (Sma), Medium (Med) and Large (Lar).

3. Results

Thirty-two types of prey were identified (Table A1). The results of the Stomach Content Analysis revealed that the major constituents of the prey items were zooplankton and chironomids. Plant material was found in 57 fish (27%), and 6 fish had otoliths from other fishes (smelt and roach) in their stomachs. Organisms belonging to other taxa were occasionally recorded, showing low values for all indices. Among zooplanktonic crustaceans, the most frequent were the family Daphniidae Ai (%) = 10.93; Fi (%) = 33.78. Species of Chironomidae were the most abundant, with larvae, pupae and adults, respectively, having values for Ai (%) = 12.50, 13.48 and 9.40 and for Fi (%) = 42.34, 38.29 and 29.28. Despite some specimens having full stomachs, most contained only low amounts of food (between 0.19% and 1.03%).
Total length among the A. fallax examined ranged from 16 to 48 cm. Exploratory data analysis revealed a multi-modal length–frequency distribution. The length–frequency distribution was similar to the Gaussian distribution, taking into account separately the length–class groups: from 16 to 27 cm (19.5% of the A. fallax samples), from 28 to 37 cm (47.7% of samples) and longer than 38 cm (32.7% of samples) (Figure 2 and Figure A1).
The results showed that the highest percentage of stomach fullness was in category 1 (47.7%) (Figure 3 and Figure A2). The highest percentage in category = 1 is in the size class 16–27 (cm) (72.7%). Furthermore, the results for the percentages of empty and full stomachs are as follows (all fish): 22.3% for empty ones (category = 0) and 7.7% for full ones (category = 4).
The results of the analysis (Kruskal–Wallis test) of the number of prey items in the stomachs among the three different size groups (16–27 cm, 28–37 cm and 38–48 cm), revealed a statistically significant difference (p-value < 0.05) for the following prey groups: Mysidae, Insecta (unknown Order) and Chironomidae. The following results (mean ± SD) were obtained for prey consumption by TL category: (1) Mysidae: 16–27 cm (0.20 ± 0.41, 28–37 cm (0.02 ± 0.14) and 38–48 cm (0.15 ± 0.45); (2) Insecta: 16–27 cm (0.48 ± 1.04), 28–37 cm (7.74 ± 14.72) and 38–48 cm (9.70 ± 18.28); (3) Chironomidae: 16–27 cm (0.41 ± 0.68), 28–37 cm (8.09 ± 12.17) and 38–48 cm (8.98 ± 16.37). The results showed that larger TL groups (28–37 cm and 38–48 cm) of A. fallax feed mostly on chironomids.
Costello’s modified graph (Figure 4) according to Amundsen et al. [35] shows clustering of values in two main areas: the upper right corner and the lower left corner of the graph. Prey located in the upper right portion (Chironomidae and Insecta for medium and large size fish) have high values of both frequency of occurrence (%) (58–66%) and prey-specific abundance (%) (15–20%), indicating that they were consumed frequently and in significant quantities. In contrast, several prey are located in the lower left portion (Chironomidae and Insecta for small size fish, and Mysidiae for fish of three size categories), characterized by a low frequency (2–20%) and low abundance (0.0006–0.6%), highlighting their minimal or occasional contribution to the overall diet. This pattern was consistently observed in the different size classes considered.

4. Discussion

The main objective of our study was to characterize the composition of A. fallax diet during their pre-spawning period within the confines of the Curonian Lagoon, Lithuania, using qualitative and quantitative analysis as far as practicable. Our working hypothesis was that the size of individuals influences the consumption of different types of prey. In our study, prey consumption of A. fallax during the pre-spawning period comprised mostly insects and small zooplanktonic crustaceans. There were few other food items found in our samples. Although not directly comparable, Aprahamian [21] showed that the total food volume per stomach contents in A. fallax was low, at less than 0.1% compared to post-spawning volumes. These results may be related to the distance from the tidal limit, since Elliott [36] found that adult sea trout decreased its feeding probability with increasing distance from the tidal limit during their upstream migration. Our results were also confirmed by the studies of the feed of A. fallax of Nachon et al. [17].
Previous feeding studies of A. fallax in other geographical areas of Europe have reported that this species is primarily ichthyophagous, feeding on small fishes and some crustaceans [11,13,15,31,37,38]. Assis et al. [13] observed that the diet of A. fallax in the Tagus estuary in Portugal was dominated by Sardina pilchardus, Engraulis encrasicolus, Pomatoschistus minutus, Phrynomantis microps and Atherina boyeri. Oesmann and Thiel [31] found that juvenile shad fed on fish (Sprattus sprattus, Osmerus aperlanus and Pomatoschistus sp.) Mysidae, Cladocera, copepods, unidentified eggs, plants and debris in the Elbe Estuary, Germany. In the Bay of Biscay, adult shad preferentially fed on anchovies (E. encrasicolus) throughout the year, with euphausids as only secondary prey [13]. In British waters, adult shad feed substantially on other fish, particularly juveniles of species from the Clupeidae family, such as S. sprattus and Cluepea harengus [16]. Although feeding mainly on small sprats, S. sprattus and marine Mysidae, in Ireland, prey consumption also included Praunus neglectus [37]. In Solway, Scotland, the diet of the A. fallax comprised mainly unidentified fish (some were small clupeids) and secondarily Malacostraca, but Copepoda were relatively unimportant as a food source [38]. Our results confirmed those of Ceyhan et al. [39] where they studied how A. fallax feeds on small fish and small crustaceans in the Aegean Sea, Turkey. The literature indicates a general trend in the Baltic Sea where A. fallax seems to prefer a diet based mostly on fish and small crustaceans [40,41]. Our results are closer to the results obtained by Nachon et al. [17]. In their study, they analyzed the diet specifically during the pre-spawning period and the results described show that the diet of A. fallax in Spain comprised a wide diversity of organisms: aquatic invertebrates, terrestrial invertebrates and other prey items such as the fish species A. boyeri [17]. Nachon et al. [17] investigated how some specimens exhibited active piscivorous nutrition. This is because P. duriense and A. boyeri were found in the stomachs of some specimens they sampled. The presence of euryhaline whole prey, such as A. boyeri, indicated that some individuals fed during the beginning of their reproductive migration. Finally, the presence of prey such as Lymnaeidae, Ancylidae and other benthic organisms with reduced drift capacity was indicative of demersal feeding patterns. Our results also confirm a trend reported by other researchers [21,22] that A. fallax does not actively feed whilst aggregating to reproduce in freshwater. In our results, whole fish were not found among the stomach contents, only otoliths of fish consumed well prior to migration into the Curonian Lagoon from the Baltic Sea.
Observations of the feeding of A. fallax larvae and/or juveniles have been published by Aprahamian [21], Oesmann, Thiel [31], LaCepède [32] and Nunn et al. [42]. Studies on the diet of sub-adult and adult A. fallax during their marine life phase or pre-, post- and during spawning migration have been conducted by Aprahamian [21], Assis et al. [13], Taverny and Elie [12], Doherty, McCathy [37], Maitland, Lyle [38], Schulze, Schirmer [43] and Bacevičius [40]. Information about food items is also provided by Wheeler [44], Ceyhan et al. [39] and Nachon et al. [17]. Most studies, with the exception of Bacevičius [40], Skora et al. [41] and Ceyhan et al. [39], concerned populations of A. fallax from Atlantic Ocean coastal waters have revealed that A. fallax feed on various small fishes and small crustaceans. Bacevičius [40] provided a preliminary analysis of the diet of A. fallax in Lithuanian coastal waters.
In the present study, the percentage of empty stomachs (23%) was within the range observed by Aprahamian [21] (0% to 69%). Although not directly comparable, Aprahamian [21] showed that the total food volume per stomach of A. fallax is low, at less than 0.1% compared to post-spawning volumes. These results may be related to the distance from the tidal limit, since Elliott [36] found that adult sea trout decreased their feeding probability with increasing distance from the tidal limit during their upstream migration. Our results were also confirmed from studies by Nachon et al. [17] on feeding of A. fallax
Reduction in feeding activity during the annual spawning period may have certain advantages. Cessation of feeding may be important for maintaining internal osmotic pressure, as suggested by Nikolsky [45]. This strategy also allows a greater body cavity volume for occupation by gonadal material, which in females means an increase in egg number and/or size. Our results contrast with the studies of A. fallax in the Baltic Sea by Skóra et al. [41], where they found that the degree of fullness of the stomach was higher among juveniles than adults.
Insects comprise much of the primary prey for omnivorous and carnivorous fish [46,47,48] and include aquatic insects in the adult and/or larval stages from the orders Diptera, Trichoptera, Odonata, Hemiptera, Coleoptera and Ephemeroptera [49,50,51,52,53] and terrestrial insects that primarily belong to the families Vespidae and Formicidae [54,55]. In previous studies, insects appear to be a well-documented part of the diet of juvenile carnivorous and omnivorous fish species, due to their dietary plasticity, and they are components of the diets of continental fish [56,57,58,59] as well as marine and euryhaline fish species found in brackish water [54,60]. Our study supports the hypothesis that there is a significant difference in the composition of the diet between different size groups for three different taxa: Mysidae, Insecta (unknown Order) and Chironomidae. The bimodal distribution observed in Costello’s modified graph (feeding strategy and niche width components of populations [35]) suggests a trophic structure dominated by a few main biota, accompanied by opportunistic or occasional consumption of other prey. The presence of prey in the upper right (frequent and abundant) indicates trophic specialization towards feeding on energetically advantageous and easily accessible sources whilst resident in the lagoon. In contrast, prey in the lower left of the graph can be interpreted as marginal components of the diet, ingested accidentally or consumed in situations of reduced availability of main food sources. Aprahamian [21] found that juvenile A. fallax are more active in searching for benthic food (Chironomidae). It is unlikely that A. fallax with their superior mouth position are morphologically adapted to feed on benthos. But some studies have shown to the contrary, that they are still able to feed on benthic organisms despite their mouth position [61]. The implication of the study by Aprahamian [21] is that juvenile A. fallax feed on drift. Our study contrasts with these previous conclusions. Probably due to a reduced availability of prey (like small fish), our results demonstrate that the adults prefer Chironomidae and Insecta (unknown Order), indicative of greater feeding adaptability and specialization of adults compared to juveniles during the pre-spawning period in the Curonian Lagoon.
The A. fallax we sampled exhibited a large size distribution, with several modes indicative of the presence of different life history stages, including juveniles, among the spawning aggregation that we sampled. The presence of juvenile fish in spawning areas, not yet fully mature and therefore not ready for reproduction, is an interesting peculiarity that is contrary to expectation. Aprahamian [21] studied how A. fallax juveniles migrate upstream in the Severn and Wye rivers in Great Britain during pre-spawning. Juveniles were present in greater quantities in the Wye than in the Severn River. This was attributed to these rivers differing in biotic and abiotic characteristics. The Severn River has a high degree of channelization with very muddy clay substrates unsuitable for the development of insect and zooplankton species. In contrast, Wye River has not been subjected to the same degree of channelization, comprising different substrates such as gravel, with greater availability of juvenile food resources (insects and zooplankton) during the spring–summer period.
Oesmann and Thiel [31], when studying the diet of A. fallax juveniles in the Elbe estuary, found plant material and insects in several samples, although a clear preference towards feeding zooplankton and other fish was evident. Hutchinson‘s [62] study also confirms these conclusions. Hutchinson [62] found insects, plant material, rotifers, copepods and cladocerans as prey of juvenile A. pseudoharengus (Adriondack lakes, North America), which is consistent with the food composition of juvenile A. fallax from the Elbe estuary. These results could indicate opportunistic behavior by both species, specifically of A. fallax juveniles in the Elbe estuary.
The Curonian Lagoon has greater similarity (biotic and abiotic factors) with the Wye River than the Severn, so in conjunction with the possible opportunistic feeding behavior observed among juveniles in the Elbe estuary, we can reasonably postulate that juvenile A. fallax accompanying the spawning aggregation we sampled in the Curonian Lagoon might have been present due to the availability of suitable food. If this were true, however, then much higher values of stomach fullness should have been evident, so some other explanation should be sought. Further research, with more extensive surveys of A. fallax and its main prey in different locations of the Curonian Lagoon with varying physical characteristics, may reveal why we found juveniles among the spawning aggregation. Conducting several successive surveys during the ice-free late spring to early autumn period at multiple locations could facilitate an analysis of spatiotemporal dynamics. They might also reveal why we found juveniles with low stomach fullness among a spawning aggregation.

5. Conclusions

Our analyses revealed significant differences in the abundance of prey categories (Chironomidae, Insecta—unknown order, and Mysidae) among size groups of A. fallax, associated with stage of maturity inferred from body length. Despite this being a spawning migration to the freshwater lagoon from the brackish Baltic Sea, juveniles were also present among the A. fallax we collected. Stomach fullness, an indicator of feeding activity, varied among size groups, with juveniles having lower values. Therefore, further investigation is required to understand the causes of low food consumption by juveniles in the lagoon and to clarify their migratory patterns.

Author Contributions

Conceptualization, E.N.; methodology, E.N., E.J. and Ž.P.; software, E.N.; validation, E.N.; formal analysis, E.N.; investigation, E.N., H.G. and Ž.P.; resources, L.L.; data curation, E.J.; writing—original draft preparation, E.N.; writing—review and editing, H.G., E.J., Ž.P. and L.L.; visualization, E.N.; supervision, L.L.; project administration, L.L.; funding acquisition, L.L. All authors have read and agreed to the published version of the manuscript.

Funding

This research was supported by PhD studies under Ecology and Environmental Sciences at the State Scientific Research Institute Nature Research Centre in collaboration with Vilnius University (contract number of PhD studies AZ1550591 and the Ministry of Environment grant number VPS–2021–121–AARP).

Institutional Review Board Statement

All sampling and surveys were conducted in accordance with the Lithuanian law. Permits for fish sampling were issued by the Environmental Protection Agency under the Ministry of Environment of the Republic of Lithuania.

Informed Consent Statement

Not applicable.

Data Availability Statement

The raw data supporting the conclusions of this article will be made available by the authors on request.

Acknowledgments

We would like to express our sincere gratitude to the members of our laboratory team for their invaluable support and dedication during the fieldwork for this research. Their expertise, hard work and collaboration were integral to the success of our study. A special thanks goes to our captain R. Rimkus for their specific contributions in helping with boats and fish sampling. We appreciate their commitment and professionalism, which made this research possible.

Conflicts of Interest

The authors declare no conflicts of interest. The funders had no role in the design of this study; in the collection, analyses or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

Abbreviations

The following abbreviations are used in this manuscript:
SCAStomach Content Analysis

Appendix A

Table A1. Diet composition of Alosa fallax in the Curonian Lagoon measured as relative abundance (Ai%) and frequency of occurrence (Fi%) per size class (Small, Medium and Large).
Table A1. Diet composition of Alosa fallax in the Curonian Lagoon measured as relative abundance (Ai%) and frequency of occurrence (Fi%) per size class (Small, Medium and Large).
Prey CategoryFamilyDevelopmental
Stage		Ai (%)Fi (%)
SmallMediumLargeSmallMediumLarge
Aquatic invertebrates
AnomopodaDaphniidaeAdult7.069.8912.486.679.687.19
MoinidaeAdult 0.001.511.900.001.381.56
BosminidaeAdult23.530.150.2013.330.400.31
ChydoridaeAdult3.530.000.982.220.000.63
Ctenopoda SididaeAdult0.000.150.780.000.201.25
UnidentifiedAdult0.001.162.160.001.583.13
CalanoidaAcartiidaeAdult2.350.611.312.220.992.19
UnidentifiedAdult3.531.871.502.222.172.19
AmphipodaGammaridaeAdult 2.350.910.854.440.991.25
UnidentifiedAdult 4.712.174.514.442.173.75
UnidentifiedLarvae11.761.060.858.892.372.19
MysidaMysidaeAdult7.060.100.5913.330.402.19
CyclopoidaCyclopidaAdult 0.000.400.720.000.790.94
MolluscaValvatidaeAdult0.000.100.780.000.200.94
Plecoptera UnidentifiedNymph0.000.200.260.000.790.63
Coleoptera UnidentifiedLarvae 4.713.083.536.676.326.56
UnidentifiedAdult3.534.594.382.227.516.88
Diptera ChironomidaeLarvae1.1814.3311.962.2212.659.38
ChironomidaePupae12.9415.6911.9620.0010.087.81
OdonataUnidentifiedNymph0.003.282.810.002.772.81
Insecta (unknown Order)UnidentifiedEmerging0.003.834.310.003.164.06
UnidentifiedLarval0.006.003.920.004.943.44
UnidentifiedPupae4.713.943.202.224.944.06
Terrestrial invertebrates
OdonataUnidentifiedAdult0.004.093.920.002.964.06
Diptera ChironomidaeAdult0.0010.399.540.008.506.88
TrichopteraUnidentifiedAdult3.531.312.352.221.984.38
EphemeropteraUnidentifiedAdult0.004.143.660.004.353.44
InsectaUnidentified 0.004.243.790.003.753.75
Other prey items
Unidentified 22.412.672.88
OsmeridaeOsmeridae 1.180.050.202.220.200.63
CyprinidaeCyprinidae 0.000.150.070.000.400.31
Eggs 2.350.610.522.221.381.56
Plant material 06.964.89
Fishes 10 00256 g0a1
Figure A1. Length–weight relationship of the twaite shad (Alosa fallax).
Figure A1. Length–weight relationship of the twaite shad (Alosa fallax).
Fishes 10 00256 g0a1
Fishes 10 00256 g0a2
Figure A2. Distribution of twaite shad (Alosa fallax) stomach fullness by length (TL).
Figure A2. Distribution of twaite shad (Alosa fallax) stomach fullness by length (TL).
Fishes 10 00256 g0a2

References

  1. Kulbicki, M.; Bozec, Y.; Labrosse, P.; Letourneur, Y.; Mou-Tham, G.; Wantiez, L. Diet composition of carnivorous fishes from coral reef lagoons of New Caledonia. Aquat. Living Resour. 2005, 18, 231–250. [Google Scholar] [CrossRef]
  2. Andrade, T.C.; Jesus, K.F.; Souza, C.C.A.; Amorim, A.F. Identificação do conteúdo estomacal de perciformes e carcharhiniformes: Contribuição ao cruzeiro cientifico no Sudeste e Sul do Brasil (Dez/2009). Rev. Ceciliana 2011, 3, 45–49. [Google Scholar]
  3. Gandini, C.V.; Boratto, I.A.; Fagundes, D.C.; Pompeu, P.S. Estudo da alimentação dos peixes no rio grande à jusante da usina hidrelétrica de Itutinga, Minas Gerais, Brasil. Série Zool. 2012, 102, 56–61. [Google Scholar] [CrossRef]
  4. Santos, L.V.; Vasconcelos-Filho, J.E.; Lira, A.S.; Soares, A.; Eduardo, L.N.; Pas-sarone, R.; Le-Loc’h, F.; Lucena-Frédou, F. Trophic ecology and ecomorphology of the Shorthead Drum, Larimus breviceps (Acan-thuriformes: Sciaenidae), from the Northeastern Brazil. Thalass. Int. J. Mar. Sci. 2022, 38, 1–11. [Google Scholar] [CrossRef]
  5. Montenegro, L.A.; Damasceno, D.N.F.; Almeida, R.G.; Chellappa, S. Biologia alimentar do mussum, Synbranchus marmoratus (Bloch, 1795) (Osteichthyes: Synbranchidae) no Açude Marechal Dutra localizado no Semi-árido Brasileiro. Biota Amaz. 2011, 1, 45–52. [Google Scholar] [CrossRef]
  6. Silveira, E.L.; Semmar, N.; Cartes, J.E.; Tuset, V.M.; Lombarte, A.; Ballestera, E.L.; Vaz-dos-Santos, A.M. Methods for trophic ecology assessment in fishes: A critical review of stomach analyses. Rev. Fish. Sci. Aquac. 2019, 28, 71–106. [Google Scholar] [CrossRef]
  7. Albertoni, E.F.; Palma-Silva, C.; Esteves, F.A. Natural diet of three species of shrimp in a tropical coastal lagoon. Braz. Arch. Biol. Technol. 2003, 46, 395–403. [Google Scholar] [CrossRef]
  8. Aprahamian, M.; Baglinière, J.-L.; Sabatie, M.; Alexandrino, P.; Thiel, R.; Aprahamian, C. Biology, status and conservation of the anadromous twaite shad Alosa fallax fallax (Lacépède, 1803). Am. Fish. Soc. Symp. 2003, 35, 103–124. [Google Scholar]
  9. IUCN. IUCN Red List of Threatened Species. Version 2010.4. 2010. Available online: www.iucnredlist.org (accessed on 27 December 2010).
  10. Volk, J.; Bekkevold, D.; Loeschke, V. Weak population differentiation in northern European populations of the endangered anadromous clupeid Alosa fallax. J. Fish Biol. 2007, 71 (Suppl. C), 461–469. [Google Scholar] [CrossRef]
  11. Whitehead, P.J.P. Clupeidae. In Fishes of the North-Eastern Atlantic and the Mediterranean; Whitehead, P.J.P., Bauchot, M.-L., Hureu, J.-C., Nielsen, J., Tortonose, E., Eds.; UNESCO: Paris, France, 1986; Volume I, pp. 271–272. [Google Scholar]
  12. Taverny, C.; Elie, P. Régime alimentaire de la grande alose Alosa alosa (Linné, 1766) et de l’alose feinte Alosa fallax (Lacépède, 1803) dans le Golfe de Gascogne [Feeding habits of allis shad Alosa alosa (Linné, 1766) and twaite shad Alosa fallax (Lacépède, 1803) in the Bay of Biscay]. Bull. Fr. Pêche Piscic 2001, 362–363, 837–852, (In French with English Summary). [Google Scholar] [CrossRef]
  13. Assis, C.A.; Almeida, P.R.; Moreira, F.; Costa, J.L.; Costa, M.J. Diet of the twaite shad Alosa fallax (Lacépède) (Clupeidae) in the River Tagus estuary, Portugal. J. Fish Biol. 1992, 41, 1049–1050. [Google Scholar] [CrossRef]
  14. Whitehead, P.J.P. FAO Species Catalogue. Vol. 7. Clupeoid Fishes of the World (Suborder Clupeoidei). An Annotated and Illustrated Catalogue of the Herrings, Sardines, Pilchards, Sprats, Shads, Anchovies and Wolf-Herrings. FAO Fish. Synop. 125(7/1):1-303. In Alosa Fallax. FishBase; Froese, R., Pauly, D., Eds.; Worldwide Web Electronic Publication: Cambridge, MA, USA; FAO: Rome, Italy, 1985; Available online: https://www.fishbase.org/search.php?region=europe (accessed on 20 April 2025).
  15. Golani, D.; Ozturk, B.; Basusta, N. Fishes of the Eastern Mediterranean. Isr. J. Aquac. Bamidgeh 2007, 59, 121. [Google Scholar] [CrossRef]
  16. Maitland, P.S.; Hatton-Ellis, T.W. Ecology of the Allis and Twaite Shad. In Conserving Natura 2000 Rivers Ecology Series No. 3; English Nature: Peterborough, UK, 2003; p. 32. [Google Scholar]
  17. Nachon, D.J.; Sanchez-Hernandez, J.S.; Vieira-Lanero, R.; Cobo, F. Feeding of Twaite Shad, Alosa fallax (Lacepede, 1803), during the upstream spawning migration in the River Ulla (NW Spain). Mar. Freshw. Res. 2013, 64, 233–236. [Google Scholar] [CrossRef]
  18. Stankus, S. Spawning Migration and Population Condition of Twaite Shad (Alosa fallax, Lacépède 1803) in Lithuania. Environ. Res. Eng. Manag. 2009, 50, 20–29. [Google Scholar]
  19. Repečka, R. Changes in biological indices and abundance of salmon, sea trout, smelt, vimba and twaite shad in the coastal zone of the Baltic Sea and Curonian Lagoon at the beginning of spawning migration. Acta Zool. Litu. 2003, 13, 195–216. [Google Scholar] [CrossRef]
  20. Thiel, R.; Riel, P.; Neumann, R.; Winkler, H.M.; Böttcher, U.; Gröhsler, T. Return of twaite shad Alosa fallax (Lacépède, 1803) to the Southern Baltic Sea and the transitional area between the Baltic and North Seas. Hydrobiologia 2008, 602, 161–177. [Google Scholar] [CrossRef]
  21. Aprahamian, M.W. The diet of juvenile and adult twaite shad Alosa fallax fallax (Lacépède) from the rivers Severn and Wye (Britain). Hydrobiologia 1989, 179, 173–182. [Google Scholar] [CrossRef]
  22. Bracken, J.; Kennedy, M. Notes on some Irish estuarine and inshore fishes. Ir. Fish. Investig. 1967, 3, 4–8. [Google Scholar]
  23. Glossary of fish terms. Available online: https://australian.museum/learn/animals/fishes/glossary-of-fish-terms/#s-section (accessed on 26 May 2025).
  24. Pliuraite, V. Species diversity of zooplankton in the Curonian Lagoon in 2001. Acta Zoologica Lituanica 2003, 13, 106–113. [Google Scholar] [CrossRef]
  25. Semenova, A.S. Quantitative characteristics of zooplankton of the Curonian lagoon taken by different sampling methods. Hydrobiol. J. 2011, 47, 112–120. [Google Scholar] [CrossRef]
  26. Integrated Taxonomic Information System (ITIS). Available online: https://www.itis.gov/ (accessed on 23 May 2025).
  27. The European Register of Marine Species (ERMS). Available online: https://www.marbef.org/data/erms.php (accessed on 23 May 2025).
  28. ICES. Identification Leaflets for Plankton. Available online: https://www.ices.dk/Science/publications/Pages/ID_leaflets_plankton.aspx (accessed on 23 May 2025).
  29. The Great International Code of Zoological Nomenclature. Available online: http://www.iczn.org (accessed on 23 May 2025).
  30. Hyslop, E.J. Stomach contents analysis: A review of methods and their application. J. Fish Biol. 1980, 17, 411–429. [Google Scholar] [CrossRef]
  31. Oesmann, S.; Thiel, R. Feeding of juvenile twaite shad (Alosa fallax Lacepede, 1803) in the Elbe Estuary. Bull. Fr. Peche Piscic. 2001, 362–363, 785–800. [Google Scholar] [CrossRef]
  32. LaCepède, B.G.E. Histoire Naturelle des Poisdons; Plassan: Paris, France, 1803; Volume 5, p. 803. [Google Scholar]
  33. Pinkas, L.; Oliphant, M.S.; Iverson, I.L.K. Food habits of albacore, bluefin tuna, and bonito in California waters. Calif. Fish Game 1971, 152, 1–105. [Google Scholar]
  34. Costello, M.J. Predator feeding strategy and prey importance: A new graphical analysis. J. Fish Biol. 1990, 36, 261–263. [Google Scholar] [CrossRef]
  35. Amundsen, P.A.; Gabler, H.M.; Staldvik, F.J. A New Approach to Graphical Analysis of Feeding Strategy from Stomach Contents Data—Modification of the Costello (1990) Method. J. Fish Biol. 1996, 48, 607–614. [Google Scholar] [CrossRef]
  36. Elliott, J.M. Stomach contents of adult sea trout caught in six English rivers. J. Fish Biol. 1997, 50, 1129–1132. [Google Scholar]
  37. Doherty, D.; O’Maoileidigh, N.; McCarthy, T.K. The biology, ecology and future conservation of twaite shad (Alosa fallax Lace’pede), allis shad (Alosa alosa L.) and killarney shad (Alosa fallax killarnensis Tate Regan) in Ireland. Biol. Environ. Proc. R. Ir. Acad. 2004, 104B, 93–102. [Google Scholar] [CrossRef]
  38. Maitland, P.S.; Lyle, A.A. Ecology of Allis Shad Alosa alosa and Twaite Shad Alosa fallax in the Solway Firth, Scotland. Hydrobiologia 2005, 534, 205–221. [Google Scholar] [CrossRef]
  39. Ceyhan, T.; Akyol, O.; Sever, T.M.; Kara, A. Diet composition of adult twaite shad (Alosa fallax) in the Aegean Sea (Izmir Bay, Turkey). J. Mar. Biol. Assoc. UK 2012, 92, 601–604. [Google Scholar] [CrossRef]
  40. Bacevičius, E. Ilgalaikė perpelės (Alosa fallax (Lacépède, 1803: Clupeidae)) mitybos ir apsikrėtimo parazitais tyrimai pietryčių Baltijoje ir Kuršių mariose [Investigation of feeding peculiarities and parasites of twaite shad (Alosa fallax (Lacépède, 1803: Clupeidae)) from Lithuanian coastal zone and the Curonian Lagoon]. Žuvininkystė Litetuvoje 2007, 7, 125–141, (In Lithuanian with English Summary). [Google Scholar]
  41. Skora, M.E.; Sapota, M.R.; Skora, K.E.; Pawelec, A. Diet of the twaite shad Alosa fallax (Lacepede, 1803) (Clupeidae) in the Gulf of Gdansk, the Baltic Sea. Oceanol. Hydrobiol. Stud. 2012, 41, 24–32. [Google Scholar] [CrossRef]
  42. Nunn, A.D.; Noble, R.A.A.; Harvey, J.P.; Cowx, I.G. The diets and parasites of larval and 0+ juvenile twaite shad in the lower reaches and estuaries of the rivers Wye, Usk and Towy, UK. Hydrobiologia 2008, 614, 209–221. [Google Scholar] [CrossRef]
  43. Schulze, S.; Schirmer, M. Die Finte (Alosa fallax) wieder in der Weser—Endlich gesicherte Daten [The twaite shad (Alosa fallax) back in the Weser—Finally validated data]. Verh. Ges. Ichthyol. Bd. 2006, 5, 269–283, (In German with English Summary). [Google Scholar]
  44. Wheeler, A. The Fishes of the British Isles and North-West Europe; Macmillan: London, UK, 1969; p. 613. [Google Scholar]
  45. Nikolsky, G.V. Special Ichthyology; National Science Foundation & Smithsonian Institution: Washington, DC, USA, 1961; p. 538. [Google Scholar]
  46. Badola, S.P.; Singh, H.R. Food and feeding habits of fishes of the Genera Tor, Puntius and Barilius. Proc. Indian Natl. Sci. Acad. B Biol. Sci. 1980, 46, 58–62. [Google Scholar]
  47. Biology, Fisheries and Conservation Status. In Migratory Fishes of South America; Carolsfeld, J., Harvey, B., Ross, C., Baer, A., Eds.; IDRC, World Bank: Washington, DC, USA, 2004; p. 388. [Google Scholar]
  48. Henry, M.; Gasco, L.; Piccolo, G.; Fountoulaki, E. Review on the use of insects in the diet of farmed fish: Past and future. Anim. Feed. Sci. Technol. 2015, 203, 1–22. [Google Scholar] [CrossRef]
  49. Ribeiro, A.R.; Biagioni, R.C.; Smith, W.S. Estudo da dieta natural da ictiofauna de um reservatorio centenario, Sao Paulo, Brasil. Iheringia. Ser. Zool. Porto Alegre 2014, 104, 404–412. [Google Scholar]
  50. Costa, I.D.; Soares, M.O. The seasonal diet of Aequidens tetramerus (Cichlidae) in a small forest stream in the Machado River basin, Rondonia, Brazil. Acta Amaz. 2015, 45, 365–372. [Google Scholar] [CrossRef]
  51. Pereira Neves, M.; Delariva, R.L.; Lazzarini Wolff, L. Diet and ecomorphological relationships of an endemic, species-poor fish assemblage in a stream in the Iguacu National Park. Neotrop. Ichthyol. 2015, 13, 245–254. [Google Scholar] [CrossRef]
  52. Severo-Neto, F.; Teresa, F.B.; Froehlich, O. Ecomorphology and diet reflect the spatial segregation between two Siluriformes species inhabiting a stream of the Bodoquena Plateau, in Central Brazil. Iheringia. Ser. Zool. Porto Alegre 2015, 105, 62–68. [Google Scholar] [CrossRef]
  53. Abilhoa, V.; Valduga, M.O.; Frehse, F.A.; Vitule, J.R.S. Use of food resources and resource partitioning among five syntopic species of Hypostomus (Teleostei: Loricariidae) in an Atlantic Forest river in southern Brazil. Zoologia 2016, 33, 1–7. [Google Scholar] [CrossRef]
  54. Dyer, D.C.; Perissinotto, R.; Carrasco, N.K. Temporal and spatial dietary dynamics of the longspine glassy (Ambassis ambassis) in the St. Lucia estuarine system, iSimangaliso Wetland Park. Water SA 2015, 41, 91–104. [Google Scholar] [CrossRef]
  55. Ferrareze, M.; Nogueira, M.G.; Casatti, L. Differences in ichthyofauna feeding habits among lateral lagoons and the river channel in a large reservoir. Braz. J. Biol. 2015, 75, 380–390. [Google Scholar] [CrossRef] [PubMed]
  56. Spataru, P.; Hepher, B.; Halevy, A. The effect of the method of supplementary feed application on the feeding habits of carp (Cyprinus carpio L.) with regard to natural food in ponds. Hydrobiologia 1980, 72, 171–178. [Google Scholar] [CrossRef]
  57. Oliveira, V.; Poleto, S.L.; Venere, P.C. Feeding of juvenile pirarucu (Arapaima gigas, arapaimidae) in their natural environment, lago Quatro Bocas, Araguaina- MT, Brazil. Neotrop. Ichthyol. 2005, 3, 312–314. [Google Scholar] [CrossRef]
  58. Abdulhakim, A.; Addo, S.; Lawan, Z.A.; Ebenezer, A. Feeding habits and conditions factor of Oreochromis niloticus in Lake Alau, Northeastern Nigeria. Int. J. Fish. Aquat. Stud. 2015, 3, 406–409. [Google Scholar]
  59. Ulrich, S.P. Native fish species boosting Brazilian’s aquaculture development. Acta Fish. Aquat. Resour. 2017, 5, 1–9. [Google Scholar] [CrossRef]
  60. Darnell, R.M. Food Habits of fishes and larger invertebrates of Lake Pontchartrain, Louisiana, an estuarine community. Inst. Mar. Sci. 1958, 5, 353–416. [Google Scholar]
  61. Janssen, J. Feeding behaviour repertoire of the alewives, Alosa pseudoharengus and the ciscoes, Coregonus hoyi and C. artedii. J. Fish. Res. Bd. Can. 1978, 35, 249–253. [Google Scholar] [CrossRef]
  62. Hutchinson, B.P. The effect of fish predation on the zooplankton of ten Adirondack lakes, with particular reference to the alewife Alosa Pseudoharengus. Trans. Am. Fish. Soc. 1971, 2, 325–335. [Google Scholar] [CrossRef]
Fishes 10 00256 g001
Figure 1. Twaite shad (Alosa fallax) sampling site (black dot).
Figure 1. Twaite shad (Alosa fallax) sampling site (black dot).
Fishes 10 00256 g001
Fishes 10 00256 g002
Figure 2. Length–frequency distribution of twaite shad (Alosa fallax) (number of fish per total length class).
Figure 2. Length–frequency distribution of twaite shad (Alosa fallax) (number of fish per total length class).
Fishes 10 00256 g002
Fishes 10 00256 g003
Figure 3. Frequency (number) of twaite shad (Alosa fallax) per degree of fullness of the stomach in three size categories.
Figure 3. Frequency (number) of twaite shad (Alosa fallax) per degree of fullness of the stomach in three size categories.
Fishes 10 00256 g003
Fishes 10 00256 g004
Figure 4. Costello graph [34,35] using weight percentage (%Wf) and frequency of occurrence (%) of the prey taxa Mysidae (Mys), Chironomidae (Chi) and Insecta (Ins) in A. fallax diet for the three different size groups: Small (Sma), Medium (Med) and Large (Lar) sampled from a spawning aggregation in the Curonian.
Figure 4. Costello graph [34,35] using weight percentage (%Wf) and frequency of occurrence (%) of the prey taxa Mysidae (Mys), Chironomidae (Chi) and Insecta (Ins) in A. fallax diet for the three different size groups: Small (Sma), Medium (Med) and Large (Lar) sampled from a spawning aggregation in the Curonian.
Fishes 10 00256 g004
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Nobili, E.; Gorfine, H.; Jakubavičiūtė, E.; Pūtys, Ž.; Ložys, L. Diet Composition of Twaite Shad, Alosa fallax (Lacépède, 1803), During the Spawning Migration to the Curonian Lagoon (Lithuania). Fishes 2025, 10, 256. https://doi.org/10.3390/fishes10060256

AMA Style

Nobili E, Gorfine H, Jakubavičiūtė E, Pūtys Ž, Ložys L. Diet Composition of Twaite Shad, Alosa fallax (Lacépède, 1803), During the Spawning Migration to the Curonian Lagoon (Lithuania). Fishes. 2025; 10(6):256. https://doi.org/10.3390/fishes10060256

Chicago/Turabian Style

Nobili, Edoardo, Harry Gorfine, Eglė Jakubavičiūtė, Žilvinas Pūtys, and Linas Ložys. 2025. "Diet Composition of Twaite Shad, Alosa fallax (Lacépède, 1803), During the Spawning Migration to the Curonian Lagoon (Lithuania)" Fishes 10, no. 6: 256. https://doi.org/10.3390/fishes10060256

APA Style

Nobili, E., Gorfine, H., Jakubavičiūtė, E., Pūtys, Ž., & Ložys, L. (2025). Diet Composition of Twaite Shad, Alosa fallax (Lacépède, 1803), During the Spawning Migration to the Curonian Lagoon (Lithuania). Fishes, 10(6), 256. https://doi.org/10.3390/fishes10060256

Article Metrics

Back to TopTop