MARINE AND FISHERY SCIENCES 35 (1): 67-80 (2022)

https://doi.org/10.47193/mafis.3512022010109

ABSTRACT. Food habits and diet composition of Patagonian flounder Paralichthys patagonicus

(Jordan, 1889) were studied on the basis of stomach content analyses from 828 specimens (512

females, 304 males, 12 unsexed) collected during 16 commercial cruises between February 2009 and

April 2010 in the Argentine-Uruguayan Coastal Ecosystem (34° S-41° S). A total of 272 stomachs

(32.9%) contained food (184 females and 84 males), among which 20 prey taxa were identified. The

most important prey category was pelagic fish, primarily Argentine anchovy (Engraulis anchoita),

followed by rough scad (Trachurus lathami). Evidence showed that females consumed a higher total

wet weight of prey compared to males. Results also suggested a specialised diet over E. anchoita,

across all sex and size groups. The estimated trophic level for the population of P. patagonicus was

4.16. This study suggests that P. patagonicus is a tertiary piscivorous consumer of the trophic food

web in the region, and reveals changes in the prey consumption compared with previous studies.

Key words: Diet, feeding strategy, spatio-temporal variation, trophic level.

Ecología trófica del lenguado patagónico Paralichthys patagonicus (Jordan, 1889) en el

Ecosistema Costero Argentino-Uruguayo

RESUMEN. Se estudiaron los hábitos alimentarios y la composición de la dieta del lenguado

patagónico Paralichthys patagonicus (Jordan, 1889) sobre la base del análisis del contenido esto-

macal de 828 especímenes (512 hembras, 304 machos, 12 indeterminados) recolectados durante 16

cruceros comerciales entre febrero de 2009 y abril de 2010 en el Ecosistema Costero Argentino-

Uruguayo (34° S-41° S). Un total de 272 estómagos (32,9%) contenían alimento (184 hembras y 84

machos), entre los que se identificaron 20 taxones de presas. La categoría de presa más importante

fue los peces pelágicos, principalmente la anchoíta argentina (Engraulis anchoita), seguida por el

surel (Trachurus lathami). La evidencia mostró que las hembras consumieron un mayor peso húme-

do total de presa en comparación con los machos. Los resultados también sugirieron una dieta espe-

cializada sobre E. anchoita para todos los sexos y tamaños. El nivel trófico estimado para toda la

población de P. patagonicus fue 4,16. Este estudio sugiere que P. patagonicus es un consumidor pis-

cívoro terciario de la trama trófica en la región, y revela cambios importantes en el consumo de pre-

sas en comparación con estudios previos.

Palabras clave: Dieta, estrategia alimenticia, variación espacio-temporal, nivel trófico.

67

*Correspondence:

andresmilessi@yahoo.com

Received: 5 September 2021

Accepted: 1 December 2021

ISSN 2683-7595 (print)

ISSN 2683-7951 (online)

https://ojs.inidep.edu.ar

Journal of the Instituto Nacional de

Investigación y Desarrollo Pesquero

(INIDEP)

This work is licensed under a Creative

Commons Attribution-

NonCommercial-ShareAlike 4.0

International License

Marine and

Fishery Sciences

MAFIS

ORIGINAL RESEARCH

Trophic ecology of Patagonian flounder Paralichthys patagonicus (Jordan,

1889) in the Argentine-Uruguayan Coastal Ecosystem

GONZALO H. TROCCOLI1, ANDRÉS C. MILESSI2, 3, *, NOEMÍ MARÍ1, DANIEL FIGUEROA4and AGUSTÍN M. DEWYSIECKI5

1Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), Paseo Victoria Ocampo Nº 1, Escollera Norte, B7602HSA -

Mar del Plata, Argentina. 2Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CIC), Argentina. 3Organización para la

Conservación de Cetáceos (OCC), Uruguay. 4Laboratorio de Biología de Peces, Instituto de Investigaciones Marinas y Costeras

(IIMyC-CONICET), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata (UNMdP), Consejo Nacional de

Investigaciones Científicas y Técnicas (CONICET), Argentina. 5Centro para el Estudio de Sistemas Marinos (CESIMAR),

Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Boulevard Brown 2915, U9120ACD - Puerto Madryn, Argentina.

ORCID Gonzalo H. Troccoli https://orcid.org/0000-0002-0057-4325, Andrés C. Milessi https://orcid.org/0000-0003-3897-4970,

Noemí Marí https://orcid.org/0000-0003-2278-6510, Daniel Figueroa https://orcid.org/0000-0003-3258-1092,

Agustín M. De Wysiecki https://orcid.org/0000-0002-0506-3495

INTRODUCTION

Predation in nature is a central ecological

process as it contributes to understanding the

interactions of predators with their prey within an

ecosystem (Elton 1927). Today, it is known that

relationships between two or more species are

described as nodes of a food web which can inter-

act with each other and, therefore, any alteration

can affect its stability (Lawton and Pimm 1978;

Sterner et al. 1997).

The main coastal fishery in Argentina is carried

out along the Argentine-Uruguayan Coastal

Ecosystem (AUCE, 34° S-41° S), namely the

Bonaerense Coastal Fishery (Carozza et al.

2004). More than 40 species are caught including

crustaceans, molluscs and fish. The latter are

grouped into the ‘varied coastal’, which is com-

posed of about 30 species, both bony and carti-

laginous fish (Lasta et al. 1998; Massa et al.

2004). In 2009, declared landings of 30 species

making up the coastal assemblage was 105,361 t,

from which 86.7% was obtained within the

AUCE (Fernández Aráoz et al. 2010).

In particular, the Patagonian flounder (Par-

alichthys patagonicus) is one of the main fishing

resources in the AUCE, due to both its excellent

meat quality and its high market price (Fabré

1992). As a result of its high commercial impor-

tance, overfishing is a major threat in the region,

leading this species to a vulnerable conservation

status (Riestra et al. 2020). Over the past decades,

annual catches ranged from 6,000 to 7,000 t

year-1, but more recently they shifted to an aver-

age of ~ 3,200 t year-1 (MAGyP 2021). In 2008,

for example, catches of P. patagonicus con-

tributed to 7% (6,930 t) of total declared landings

in the AUCE (Rico and Lagos 2010), whereas in

2009, this percentage slightly decreased to 6,4%

(5,890 t) (Fernández Aráoz et al. 2010). During

2020, the capture of flounders in Argentina and

Uruguay diminished significantly to 1,891 t,

accounting for 2.2% of total harvest (CTMFM

2021). Nevertheless, P. patagonicus continues to

be the one that predominates the catches among

the four species of flounder landed in the AUCE

(Rico and Perrotta 2009; Rico 2010).

Paralichthys patagonicus is a benthic species

inhabiting soft bottoms (Menni 1983), character-

ized as an ichthyophagous as well as a generalist

mesopredator (Carneiro 1995; Sánchez and Díaz

de Astarloa 1999). Its diet is based on fish with

demersal-benthic habits (40.4%), mainly banded

cusk-eel Raneya brasiliensis, and followed by

pelagic fish (31.0%), including rough scad Tra-

churus lathami and Argentine anchovy Engraulis

anchoita (Sánchez and Díaz de Astarloa 1999).

Previous studies were based on qualitative analy-

sis and did not provide the feeding strategy of P.

patagonicus, nor its trophic role or any changes in

diet concerning sex and size. Therefore, this work

aimed to quantitatively determine the diet compo-

sition of P. patagonicus and find possible differ-

ences in prey consumption between sex and size

groups, as well as its feeding strategies and troph-

ic position in the AUCE.

MATERIALS AND METHODS

Study area

The study area is located in the AUCE region

at the northern part of the Argentine Continental

Shelf, between 34° S and 41° S and from the

coastline to the 50 m deep isobath (Figure 1). On

a large scale, the AUCE is influenced by various

sources of oceanographic variability. In the north-

ern area, it receives the influence of the coastal

branch of the Brazil Current and the freshwater

discharge from the Río de la Plata (Guerrero et al.

1997). In the southern area, it is influenced by the

discharge of the Negro and Colorado rivers and

the salty waters of San Matías Gulf (Lucas et al.

2005). In the outer eastern waters, it receives the

68 MARINE AND FISHERY SCIENCES 35 (1): 67-80 (2022)

influence of the Continental Shelf Current (Lucas

et al. 2005).

Data sources

P. patagonicus were obtained from 16 fishery

landings of the commercial coastal fleet, carried

out between February 2009 and April 2010 in the

AUCE. Total length (LT, to the nearest cm), total

wet weight (WT, to the nearest g) and sex were

recorded from each specimen, and stomachs were

frozen to analyse prey composition.

Stomach content analysis

Prey items were identified to the lowest possi-

ble taxonomic level, counted and weighed. In the

case of fish remains such as otoliths, LT -WTand

otolith size-LTregression curves to estimate the

LTand WTof the prey were used (Koen Alonso et

al. 1998; Waessle et al. 2003; Díaz de Astarloa

2005; Barquete et al. 2008). In order to quantify

the importance of each prey item in the diet of P.

patagonicus, the percentage in number (%N),

percentage in WT(%W), frequency of occurrence

(%FO), Index of Relative Importance or IRI [IRIi

= %FOi× (%Ni+ %Wi) for each prey item i]

(Pinkas et al. 1971), and the IRI expressed as a

percentage (%IRI, Cortés 1997) were calculated.

Representativeness of stomach samples in the

description of the diet of species was analysed by

the minimum sample size and the intrinsic vari-

ability using randomization that considered

300,000 arrangements that produced curves for

accumulated prey groups (i.e. pelagic fish, dem-

ersal fish, benthic fish, molluscs and crus-

taceans). For each randomization, the minimum,

mean, maximum and coefficient of variation were

obtained, which made possible to assess whether

analysed sample met the minimum sample size.

Variations in the diet with sex and size

Possible quantitative differences in diet be-

tween females and males, and among size groups

of P. patagonicus, were analysed by running a

69

TROCCOLI ET AL.: DIET COMPOSITION OF PATAGONIAN FLOUNDER

Figure 1. Study area (grey shade) from which samples were taken within the Argentine-Uruguayan Coastal Ecosystem (AUCE),

delimited by the 50 m isobath.

35°

55°63°

Southwest Atlantic

37°

39°

41°

53°57°61° 59°

100 km

Uruguay

Argentina

South America

50 m

S

W

non-parametric Mann-Whitney and Kruskal-Wal-

lis tests, respectively. Data were arranged into

three different size groups according to the crite-

ria provided by previous growth studies of the

species (Riestra 2010): Group I (22-34 cm LT; 2

to 4 years), Group II (35-47 cm LT; 4 to 7 years)

and Group III (> 47 cm LT; > 8 years). In addi-

tion, prey type composition (main prey cate-

gories) was examined between sexes and among

size groups.

Feeding strategy

In order to determine the feeding strategy (i.e.

generalist or specialist) of P. patagonicus and the

importance of the prey, the graphic method of

Amundsen et al. (1996) was used. The specific

abundance of prey iwas plotted against %FOi.

Trophic level

The trophic level (TL) makes reference to the

position of a species or population in the trophic

web and its classification ranges from primary

producers with a value of 1 to large top predators

with values of 4 or 5 (Lindeman 1942). In the

present work, the fractional form was used as

suggested by Odum and Heald (1975), and then,

TL was calculated for the population of P. patag-

onicus by applying the methodology suggested

by Cortés (1999):

where TL is the trophic level of P. patagonicus

(predator), Pjis the proportion of the prey item jin

the predator’s stomach, TLjis the trophic level of

each prey item j, and nis the number of prey items

recorded in the stomach of the predator. Trophic

level of prey was obtained from online resources

(Froese and Pauly 2019) and published literature

(Jaureguizar and Milessi 2008; Milessi 2008).

TL 1= +

j1=

n

PTL´

jj

å)

RESULTS

Stomach contents

Out of 828 stomachs of P. patagonicus

analysed, 272 (32.9%) presented prey contents,

of which 184 were females and 84 males. Of the

stomachs with contents, 36 (13.24%) correspond-

ed to size group I, 176 (64.71%) to size group II,

and 60 (22.05%) to size group III. In a very low

percentage of specimens (1.45%), the sex could

not be determined. The cumulative curves of the

number of prey categories as a function of the

number of stomachs sampled with prey content

indicated that the number of samples was suffi-

cient to describe and quantitatively analyse the

diet of P. patagonicus and compare it between

size groups and sexes (Figure 2).

Twenty prey items were identified, correspon-

ding to three taxonomic groups: fish, molluscs

and crustaceans. Fish were the most frequently

encountered prey (%FO = 87.55), followed by

crustaceans (%FO = 8.20) and cephalopod (%FO

= 3.41) (Table 1). The most frequent prey item

was E. anchoita (%FO = 37.60), followed by T.

lathami (%FO = 18.12) and R. brasiliensis (%FO

= 9.19). The most common prey item was E.

anchoita (%N = 52.94), followed by T. lathami

(%N = 18.21) (Table 1). Regarding the percent-

age by weight, fish were the most important

group (%W = 96.53), followed by molluscs (%W

= 2.31) and crustaceans (%W = 0.71) (Table 1).

The best-represented species by weight were E.

anchoita (%W = 36.62) and T. lathami (%W =

26.17). The Relative Importance Index (%IRI)

indicated that the most important item in the diet

was fish (98.73), followed by crustaceans (0.91)

and cephalopods (0.35) (Table 1). Among fish

prey, the species with the highest contribution

was E. anchoita (%IRI = 74.25), followed by T.

lathami (%IRI = 18.22) and R. brasiliensis (%IRI

= 4.18). Among cephalopod prey, squid (Loligo

70 MARINE AND FISHERY SCIENCES 35 (1): 67-80 (2022)

sanpaulensis) accounted for 0.35%, and the

Argentine red shrimp (Pleoticus muelleri) repre-

sented 0.86% among crustaceans.

Variations in the diet according to sex and size

Results revealed that females consumed a

greater amount of food than males, both in num-

ber and weight (Figure 3 A). Statistically signifi-

cant differences between sexes were observed in

both the number (Mann-Whitney, W = 8579; p=

0.006), and weight (Mann-Whitney, W = 9910; p

< 0.001) of prey consumed. Size groups con-

sumed the same amount of prey in number but

not in weight, being size group III the category

consuming the greatest weight of prey (Figure 3

B). Statistical analysis indicated no significant

differences in number of prey consumed by size

groups (Kruskal-Wallis, H = 4.74, p = 0.192) and

significant differences in weight of prey

(Kruskal-Wallis, H = 39.14, p< 0.001).

Pelagic fish were by far the predominant prey

category both in number and weight in stomachs

of all sex and size groups (Figure 4 A and B). The

second most important prey category for group I

was crustaceans, while benthic and demersal fish

(number and weight) for groups II and III (Figure

4 B). Consumption of crustaceans was negligible

across specimens larger than 47 cm LT.

Feeding strategy

Based on Amundsen’s graphical method, P.

patagonicus presented a specialist type strategy

71

TROCCOLI ET AL.: DIET COMPOSITION OF PATAGONIAN FLOUNDER

Figure 2. Cumulative number of prey categories of Patagonian flounder Paralichthys patagonicus as a function of stomachs

sampled with prey content, arranged by sex or size group. Group I = 23-34 cm LT, Group II = 35-47 cm LT, and Group

III = > 47 cm LT. Mean values are denoted by points and standard deviation by error bars. Stomachs with only bony fish

and/or unidentified rests were excluded from this analysis.

1

2

3

4

5

0 50 100 150 200 250

1

2

3

4

5

0 50 100 150

1

2

3

4

5

0 20406080

1

2

3

4

5

0 10203040

1

2

3

4

5

0 50 100 150

1

2

3

4

5

0204060

Number of stomachs

Number of prey categories

All Females Males

Group I Group II Group III

due to the consumption of E. anchoita and T. lath-

ami as main prey items (Figure 5). Argentine

anchovy was the most selected prey among both

female and male groups (Figure 5). Juvenile sizes

of flounder specialized only on E. anchoita,

whereas intermediate sizes on E. anchoita and T.

lathami, and larger sizes on E. anchoita, T. latha-

mi and R. brasiliensis (Figure 5).

72 MARINE AND FISHERY SCIENCES 35 (1): 67-80 (2022)

Table 1. Diet composition of Patagonian flounder (Paralichthys patagonicus) caught within the Argentine-Uruguayan Coastal

Ecosystem (AUCE). Frequency of occurrence (%FO), number (%N), total wet weight (%W), and Index of Relative

Importance (%IRI) were indicated and expressed in percentages. TL = trophic level.

Prey TL %N %FO %W %IRI

Chordata

Osteichthyes 88.51 87.18 96.53 98.73

Conger orbignyanus 3.40 1.68 2.21 1.68 0.16

Cynoscion guatucupa 3.74 3.36 4.41 6.41 0.97

Dules auriga 3.49 1.40 1.47 2.91 0.14

Engraulis anchoita 2.73 52.94 37.60 36.62 74.25

Menticirrhus americanus 3.73 0.28 0.37 0.04 0.00

Mullus argentinae 3.73 0.84 1.10 0.36 0.03

Prionotus nudigula 3.73 0.28 0.37 0.27 0.00

Raneya brasiliensis 3.73 7.28 9.19 13.89 4.18

Symphurus spp. 3.73 0.28 0.37 2.30 0.02

Trachurus lathami 3.51 18.21 18.12 26.17 18.22

Umbrina canosai 3.73 1.12 1.47 2.57 0.12

Urophycis brasiliensis 3.80 0.84 1.10 0.68 0.04

Remains - - 9.40 2.63 0.60

Chondrichthyes - 0.28 0.37 0.32 0.00

Rajidae 3.59 0.28 0.37 0.32 0.00

Mollusca

Cephalopoda - 3.08 3.41 2.31 0.35

Loligo sanpaulensis 3.04 2.80 3.35 2.09 0.35

Octopus spp. 3.20 0.28 0.37 0.22 0.00

Arthropoda

Crustacea - 8.13 8.20 0.71 0.91

Grapsidae 2.00 1.68 1.10 0.03 0.04

Heterosquilla platensis 2.00 0.56 0.74 0.26 0.01

Leurocyclus tuberculosus 2.00 0.28 0.37 0.00 0.00

Pinixa patagonica 2.00 0.28 0.37 0.00 0.00

Pleoticus muelleri 2.20 5.33 5.62 0.42 0.86

Unidentified remains - - 0.84 0.13 0.01

Trophic level

Estimated TL for the population of P. patago-

nicus between 2009 and 2010 was 4.16, with

females presenting a value of 4.18 and males a

value of 4.10.

DISCUSSION

Patagonian flounder diet presented 20 prey

items and was specialized in pelagic fish. The

main consumed species were E. anchoita, fol-

lowed by T. lathami and R. brasiliensis. This

study supports previous observations that P.

patagonicus is an ichthyophagous predator,

which bases its diet preferentially on E. anchoi-

ta, allowing it to be allocated as a tertiary con-

sumer in the AUCE food web. The number of

stomachs analysed was statistically adequate to

describe the diet of P. patagonicus. Only 33% of

the analysed specimens presented food in their

stomachs, which is consistent with other studies

on ichthyophagous bony fishes and flounder

species (Carneiro 1995; Sánchez and Díaz de

Astarloa 1999; Link et al. 2002). A high number

of empty stomachs could be a consequence of

fish suffering stress or water pressure differ-

ences during their extraction from the aquatic

73

TROCCOLI ET AL.: DIET COMPOSITION OF PATAGONIAN FLOUNDER

Figure 3. Diet composition (in number and wet weight of prey) of Patagonian flounder Paralichthys patagonicus arranged by

sex (A) and size groups (B). Group I = 23-34 cm LT, Group II = 35-47 cm LT, and Group III = > 47 cm LT. Asterisks

indicate significant differences.

0

1

2

Number of prey

0

1

2

3

0

10

20

30

Male Female

Wet weight of prey (g)

0

10

20

30

40

50

Group I Group III

AB

*

**

*

**

*

**

***

Group II

environment, a process manifested with the

stomach eversion or regurgitation of contents

(Bowman 1986). In particular, regurgitations

could be one factor explaining why the propor-

tion of individuals with stomach content did not

exceed 1/3 of the total, as it was repeatedly

observed in P. patagonicus being caught on

fishing gear (pers. obs. A Milessi). In addition,

the samples used in this study came from bot-

tom trawl fishing operations which are less like-

ly to have associated bias regarding regurgita-

tion rate, compared to other fishing gears (e.g.

longlines).

Patagonian flounder bases its diet primarily on

bony fish. Ichthyophagy seems to be a character-

istic of intermediate and large-sized flounders

like the species studied here, e.g., P. dentatus

(Link et al. 2002), P. orbignyanus (Norbis and

Galli 2004; López Cazorla and Forte 2005);

Syacium micrurum (Marques et al. 2009), and

Cyclopsetta panamensis (Amezcua and Portillo

2010), with a less important presence of crus-

taceans and molluscs in the diet. This character-

istic is common in P. patagonicus from both

southern Brazil (Carneiro 1995) and AUCE

(Sánchez and Díaz de Astarloa 1999). However,

P. patagonicus have changed past feeding pat-

terns observed in the AUCE between years 1992-

1993, when the diet was based predominantly on

R. brasiliensis, followed by T. lathami and to a

lesser extent by E. anchoita (Sánchez and Díaz

de Astarloa 1999). This situation was also

observed in other piscivorous fish like Percophis

brasiliensis (Milessi and Marí 2012) and

74 MARINE AND FISHERY SCIENCES 35 (1): 67-80 (2022)

Figure 4. Prey type composition of Patagonian flounder Paralichthys patagonicus arraged by sex (A) and size groups (B). Values

are expressed as percentage of total number and wet weight of main prey categories. Group I = 23-34 cm LT, Group II

= 35-47 cm LT, and Group III = > 47 cm LT.

Crustaceans Molluscs Benthic ﬁsh Demersal ﬁsh Pelagic ﬁsh

Female Male

0

20

40

60

80

Total number of prey (%)

Female Male

0

20

40

60

80

Total wet weight of prey (%)

Group I Group II Group III

AB

Squalus acanthias (Belleggia et al. 2012), which

would reflect a change in the structure of the

AUCE trophic web, mainly due to fishing

exploitation (Jaureguizar and Milessi 2008).

Another explanation for the observed shift

between past and present diet may be due to a

variation in the spatial operability of the coastal

fishing fleet, which currently operates in areas

that were not previously used, and consequently,

prey captured by P. patagonicus in the present

could be different from those found in stomachs

from previous studies.

Statistical differences in diet between sexes

found in P. patagonicus are likely a result of

females consuming more prey both in number

and weight because they attain larger sizes than

males (Riestra 2010), and therefore have a higher

consumption rate, greater stomach capacity and

higher energy requirements (e.g. Scharf et al.

2000; Vögler et al. 2009). Although not possible

to evaluate in this study, it has been proposed

that there is a spatial overlap between sexes

(Riestra 2010), suggesting that females and

males would feed on the same prey but in differ-

ent quantities. This last suggestion is in line with

a study carried out on the Uruguayan coast,

where no differences were observed in the prey

type consumption between sexes of P. patagoni-

cus (Correa 2011).

Furthermore, Amundsen graphical results indi-

cated that P. patagonicus is specialized in con-

suming E. anchoita and T. lathami, and this pref-

75

TROCCOLI ET AL.: DIET COMPOSITION OF PATAGONIAN FLOUNDER

E. anchoita

T. lathami

E. anchoita

T. lathami

E. anchoita

T. lathami

E. anchoita

T. lathami

E. anchoita

R. brasiliensis

T. lathami

Group I Group II Group III

Total Females Males

0 25 50 75 100 0 25 50 75 100 0 255075100

0

25

50

75

100

0

25

50

75

100

Abundance (%)

Frequency of occurrence (%)

Figure 5. Abundance (% total wet weight) versus frequency of occurrence (% in number) of each prey found in stomachs of

Patagonian flounder (Paralichthys patagonicus) arranged by sex and size. Group I = 23-34 cm LT, Group II = 35-47 cm

LT, and Group III = > 47 cm LT. The analysis is based on the method in Amundsen et al. (1996) to determine feeding

strategies of fish. Each prey is represented by a unique symbol; only names from abundant and frequently occurring prey

are shown to facilitate visualization. Darker colours in symbols and prey names indicate higher abundance and frequency

of occurrence, respectively.

erence increased with size. This was expected

given that E. anchoita is the most abundant fish

species in the AUCE with a biomass estimated

between 1,000,000 and 5,000,000 t (Hansen and

Madirolas 1996; Hansen et al. 2007; Pájaro et al.

2009), it represents the main food source not only

for P. patagonicus but also for other teleosts

(Bergonzi 1997; Sánchez 2002; Giberto 2008,

Milessi and Marí 2012) and chondrichthyans

(Vögler et al. 2003; Belleggia et al. 2011), as

well as seabirds (Silva et al. 2000; Mauco et al.

2001; Mauco and Favero 2004; Barquete et al.

2008) and marine mammals (Rodríguez et al.

2002; Suárez et al. 2005). Dense shoals formed

near the seafloor by E. anchoita as a result of

daily vertical migrations (Hansen 2004), would

allow predation by P. patagonicus in the AUCE.

Therefore, P. patagonicus specialization on E.

anchoita should be interpreted with caution

because it is possible that the high consumption

arises from the abundance of prey in the habitats

used by the predator.

Molluscs and crustaceans were more con-

sumed by P. patagonicus of smaller sizes than

larger sizes. This behaviour was also observed in

other congeners like P. isosceles, (García 1987)

and P. orbignyanus (López Cazorla and Forte

2005), in which smaller sizes preyed more on

crustaceans and molluscs. This pattern is proba-

bly explained by the ability of smaller fish sizes

to capture small and less motile prey (e.g., mol-

luscs and crustaceans), while bigger and more

dynamic prey are captured as individuals reach

greater size and experience in predation (Link et

al. 2014).

The increase in the size of the consumed prey

can be attributed to the increase in the size of the

predator’s mouth (Stoner and Livingston 1984;

Mittelbach and Persson 1998), or to the elevated

metabolic requirement for movement, growth

and reproduction that is supported by the con-

sumption of prey with higher energy value

(Scharf et al. 2000). In this sense, pelagic fish

have a higher lipid content and therefore a higher

amount of calories (Massa et al. 2013); e.g. E.

anchoita has a value of 129 kcal and T. lathami

of 149 kcal, whereas the squid L. sanpaulensis of

80 kcal and Argentine red shrimp P. muelleri of

97 kcal (Mendez et al. 1996; Celik 2008). Thus,

as flounders grow, they need to feed on prey that

meets their basic energy requirements, which

would be achieved with the increasing consump-

tion of small pelagic fish.

Finally, the estimated TL (4.16) allowed the

identification of the Patagonian flounder as a ter-

tiary ichthyophagous consumer, a position similar

to that outlined in the southern coasts of Brazil

(TL = 4.18; Carneiro 1995). It represents an

important predator of the Argentine anchovy (E.

anchoita), which is the pelagic species with the

highest abundance and widest geographic distri-

bution in the Southwest Atlantic, ranging from

24° S to 48° S, with biomass estimates in the

order of 5,000,000 t (Hansen et al. 2010). This

characteristic highlights the role of P. patagoni-

cus in regulating the abundance of its prey,

among which the main prey not only represents

the sustenance of a large number of marine fish,

mammals and birds but it also contributes to be

an important fishery resource in the AUCE

(Hansen et al. 2010).

ACKNOWLEDGMENTS

Authors thank the people involved in the proj-

ect Especies Demersales Costeras from Instituto

Nacional de Investigación y Desarrollo Pesquero

(INIDEP, Argentina) for their kind predisposition

to prepare this work. To colleagues A. Jau-

reguizar, J. Waessle and J. Rodriguez for their

contributions and collaboration. A.C.M. wants to

acknowledge support from ‘Un Solo Mar’ project.

We thank the two anonymous referees who pro-

vided substantial improvements to the manu-

script. This work is part of the undergraduate the-

sis of G. Troccoli. INIDEP Contribution no 2257.

76 MARINE AND FISHERY SCIENCES 35 (1): 67-80 (2022)

REFERENCES

AMEZCUA F, PORTILLO A. 2010. Hábitos alimenti-

cios del lenguado panámico Cyclopsetta

panamensis (Paralichthyidae) en el Sureste

del Golfo de California. Rev Biol Mar

Oceanogr. 45: 335-340.

AMUNDSEN PA, GABLER HM, STALDVIK FJ. 1996.

A new approach to graphical analysis of feed-

ing strategy from stomach contents data-mod-

ification of the Costello (1990) method. J Fish

Biol. 48: 607-614.

BARQUETE V, B UGONI L, VOOREN CM. 2008. Diet

of Neotropic cormorant (Phalacrocorax

brasilianus) in an estuarine environment. Mar

Biol. 153: 431-443.

BELLEGGIA M, FIGUEROA DE, SÁNCHEZ F, BRE-

MEC C. 2011. The feeding ecology of Mustelus

schmitti in the southwestern Atlantic: geo-

graphic variations and dietary shifts. Environ

Biol Fish. 95: 99-114.

BELLEGGIA M, FIGUEROA D, SÁNCHEZ F, BREMEC

C. 2012. Long-term changes in the spiny dog-

fish (Squalus acanthias) trophic role in the

southwestern Atlantic. Hydrobiologia. 684:

57-67.

BERGONZI C. 1997. Interrelaciones tróficas de

algunas especies de peces del área costera de

la Provincia de Buenos Aires [tesis de licen-

ciatura]. Mar del Plata: Facultad de Ciencias

Exactas y Naturales, Universidad Nacional de

Mar del Plata, 27 p.

BOWMAN RE. 1986. Effect of regurgitation on

stomach content data of marine fishes. Envi-

ron Biol Fish. 16 (1): 171-181.

CARNEIRO MH. 1995. Reprodução e alimentação

dos linguados Paralichthys patagonicus e

Paralichthys orbignyanus (Pleuronectofor-

mes: Bothidae), no Rio Grande do Sul, Brasil

[tesis de mestrado]. Río Grande: Universidad

de Río Grande. 181 p.

CAROZZA C, LASTA C, RUARTE C, COTRINA C,

MIANZAN H, ACHA M. 2004. Corvina rubia

(Micropogonias furnieri). In: SÁNCHEZ RP,

BEZZI S, editors. El Mar Argentino y sus recur-

sos pesqueros. Tomo 4. Los peces marinos de

interés pesquero. Caracterización biológica y

evaluación del estado de explotación. Mar del

Plata: Instituto Nacional de Investigación y

Desarrollo Pesquero (INIDEP). p. 255-270.

CELIK M. 2008. Seasonal changes in the proxi-

mate chemical compositions and fatty acids of

chub mackerel (Scomber japonicus) and horse

mackerel (Trachurus trachurus) from the

north eastern Mediterranean Sea. Int J Food

Sci Tech. 5: 933-938.

CORREA P. 2011. Estimación y análisis del consu-

mo de alimento en peces del Río de la Plata y

Costa Atlántica Uruguaya [tesis de grado].

Facultad de Ciencias, Universidad de la Repú-

blica. 46 p.

CORTÉS E. 1997. A critical review of methods of

studying fish feeding based on analysis of

stomach contents: application to elasmo-

branches fishes. Can J Fish Aquat Sci. 54:

726-738.

CORTÉS E. 1999. Standardized diet compositions

and trophic levels in sharks. ICES J Mar Sci.

56: 707-717.

[CTMFM] COMISIÓN TÉCNICA MIXTA DEL FRENTE

MARÍTIMO. 2021. Desembarques del área del

tratado. [accessed 2021 November].

http://www.ctmfm.org/archivos-de-captura/.

DÍAZ DE ASTARLOA JM. 2005. Osteología craneal

comparada de tres especies de lenguado del

Género Paralichthys (Pleuronectiformes,

Paralychthyidae) del Atlántico suroccidental.

Rev Chil Hist Nat. 78: 343-391.

ELTON C. 1927. Animal ecology. New York:

Macmillan. 209 p.

FABRÉ NN. 1992. Análisis de la distribución y

dinámica poblacional de lenguados de la Pro-

vincia de Buenos Aires (Pisces, Bothidae)

[tesis doctoral]. Mar del Plata: Facultad de

Ciencias Exactas y Naturales, Universidad

Nacional de Mar del Plata. 266 p.

77

TROCCOLI ET AL.: DIET COMPOSITION OF PATAGONIAN FLOUNDER

FERNÁNDEZ ARÁOZ NC, LAGOS N, CAROZZA C.

2010. Asociación Íctica Costera Bonaerense

“Variado Costero”. Capturas declaradas por la

flota comercial argentina durante el año 2009.

Inf Téc INIDEP Nº 34/2010. 32 p.

FROESE R, PAULY D. 2019. FishBase. www.fish-

base.org/.

GARCÍA M. 1987. Pleuronectiformes de la Argen-

tina, IV. Alimentación de Paralichthys isosce-

les (Bothidae, Paralichthinae). Rev Mus La

Plata (Nueva Serie) (Secc Zool). 21: 111-125.

GIBERTO DA. 2008. Estructura de la comunidad

bentónica y ecología trófica de Scienidae

(Phisces; Osteichthyes) en el Estuario del Río

de la Plata [tesis doctoral]. Universidad

Nacional del Comahue. 224 p.

GUERRERO RA, ACHA M, FRAMIÑAN MB, LASTA

C. 1997. Physical oceanography of the Río de

la Plata Estuary, Argentina. Cont Shelf Res.

17: 727-742.

HANSEN JE. 2004. Anchoíta (Engraulis anchoita).

In: SÁNCHEZ RP, BEZZI S, editors. El Mar

Argentino y sus recursos pesqueros. Tomo 4.

Los peces marinos de interés pesquero. Carac-

terización biológica y evaluación del estado de

explotación. Mar del Plata: Instituto Nacional

de Investigación y Desarrollo Pesquero

(INIDEP). p. 101-115.

HANSEN JE, BURATTI CC, GARCIARENA AD. 2010.

Diagnóstico de la población de anchoíta al sur

de 41° S mediante un modelo de producción

estructurado por edades y estimación de cap-

turas biológicamente aceptables en el año

2010. Inf Téc Of INIDEP Nº 6/2010. 16 p.

HANSEN JE, GARCIARENA AD, BURATTI CC. 2007.

Evolución entre los años 1990 y 2006 de la

población de anchoita (Engraulis anchoita) al

norte de 41° S, y estimación de una captura

biológicamente aceptable durante el año 2007.

Inf Téc INIDEP Nº 53/2007. 23 p.

HANSEN JE, MADIROLAS A. 1996. Distribución,

evaluación acústica y estructura poblacional

de la anchoita. Resultados de las campañas del

año 1993. Rev Invest Desarr Pesq. 10: 5-21.

JAUREGUIZAR AJ, MILESSI AC. 2008. Assessing

the sources of the fishing down marine food

web process in the Argentinean-Uruguayan

Common Fishing Zone. Sci Mar. 72: 25-36.

KOEN ALONSO M, CRESPO EA, GARCÍA NA,

PEDRAZA SN, COSCARELLA M. 1998. Diet of

dusky dolphins, Lagenorhynchus obscurus, in

waters of Patagonia, Argentina. Fish Bull. 96:

366-374.

LASTA C, BREMEC C, MIANZÁN H. 1998. Áreas

ícticas costeras en la Zona Común de Pesca

Argentino-Uruguaya (ZCPAU) y en el litoral

de la provincia de Buenos Aires. In: LASTA C,

editor. Resultados de una campaña de evalua-

ción de recursos demersales costeros de la

Provincia de Buenos Aires y litoral Uruguayo.

Noviembre, 1994. INIDEP Inf Téc. 21: 91-

101.

LAWTON JH, PIMM SL. 1978. Population dynam-

ics and the length of food chains (reply).

Nature. 272: 190.

LINDEMAN RL. 1942. The trophic-dynamic aspect

of ecology. Ecology. 23: 399-418.

LINK JS, BOLLES K, MILLIKEN CG. 2002. The

feeding ecology of flatfish in the Northwest

Atlantic. J Northw Atl Fish Sci. 30: 1-17.

LINK JS, SMITH BE, PACKER DB, FOGARTY MJ,

LANGTON RW. 2014. The trophic ecology of

flatfishes. In: GIBSON RN, NASH RDM, GEF-

FEN AJ, VAN DER VEER HW, editors. Flatfis-

hes: biology and exploitation. Hoboken: John

Wiley & Sons p. 283-313.

LÓPEZ CAZORLA A, FORTE S. 2005. Food and

Feeding Habits of Flounder Paralichthys

orbignyanus (Jenyns, 1842) in Bahía Blanca

Estuary, Argentina. Hydrobiologia. 549: 251-

257.

LUCAS AJ, GUERRERO R, MIANZAN H, ACHA M,

LASTA C. 2005. Coastal oceanographic

regimes of the Northern Argentine Continental

Shelf (34°-43° S). Estuar Coast Shelf Sci. 65:

405-420.

[MAGYP] MINISTERIO DE AGRICULTURA GANADE-

RÍA Y PESCA. 2021. Desembarques de capturas

78 MARINE AND FISHERY SCIENCES 35 (1): 67-80 (2022)

marítimas totales. [accessed 2021 November].

https://www.magyp.gob.ar/sitio/areas/pesca_

maritima/desembarques/.

MARQUES JF, TEIXEIRA CM, PINHEIRO A, PESCHKE

E, CABRAL HN. 2009. A multivariate approach

to the feeding ecology of the Channel floun-

der, Syacium micrurum (Pisces, Pleuronecti-

formes), in Cape Verde, Eastern Atlantic.

Cienc Mar. 35: 15-27.

MASSA A, HOZBOR N, COLONELLO J. 2004. Situa-

ción actual y avances en el estudio de los

peces cartilaginosos. Inf Téc Int DNI-INIDEP

Nº 57/2004. 18 p.

MASSA AE, FERNÁNDEZ COMPÁS AS, PENNISI

FARELL SC, MANCA EA. 2013. Composición

química y perfil de ácidos grasos de la ancho-

íta bonaerense en función del tamaño de los

ejemplares y la zona de pesca. Rev Invest

Desarr Pesq. 23: 161-174.

MAUCO L, FAVERO M. 2004. Diet of the common

tern (Sterna hirundo) during the nonbreeding

season in Mar Chiquita Lagoon, Buenos Aires,

Argentina. Ornit Neot. 15: 121-131.

MAUCO L, FAVERO M, BÓMS. 2001. Food and

feeding biology of the Common Tern during

the nonbreeding season in Samborombón Bay,

Buenos Aires, Argentina. Waterbirds. 24: 89-

96.

MENDEZ E, GONZÁLEZ R, INOCENTE G, GIUDICE

H, GROMPONE M. 1996. Lipid content and

fatty Acid composition of fillets of six fishes

from the Rio de la Plata. J Food Compos Anal.

9: 163-170.

MENNI RC. 1983. Los peces en el medio marino.

Buenos Aires: Estudio SIGMA. 169 p.

MILESSI AC. 2008. Modelación ecotrófica para el

Ecosistema Costero Bonaerense (34º-41ºS)

años ’81-83. Inf Téc INIDEP Nº 8/2008. 55 p.

MILESSI AC, MARÍ N. 2012. Ecología trófica del

pez palo, Percophis brasiliensis (Quoy & Gai-

mard, 1825) en el Ecosistema Costero Argen-

tino-Uruguayo (34-41º S). Inf Invest INIDEP

Nº 65/2012. 12 p.

MITTELBACH GG, PERSSON L. 1998. The ontoge-

ny of piscivory and its ecological conse-

quences. Can J Fish Aquat Sci. 55: 1454-1465.

NORBIS W, GALLI O. 2004. Feeding habits of the

flounder Paralichthys orbignyanus (Valenci-

ennes, 1842) in a shallow coastal lagoon of the

southern Atlantic Ocean: Rocha, Uruguay.

Cienc Mar. 30: 619-626.

ODUM WE, HEALD EJ. 1975. The detritus-based

food web of an estuarine mangrove communi-

ty. In: CRONIN LE, editor. Estuarine research.

Vol. 1. New York: Academic Press. p. 265-

286.

PÁJARO M, HANSEN JE, LEONARDUZZI E, GARCIA-

RENA AD. 2009. Biomasa de los reproductores

de la población bonaerense de anchoita

(Engraulis anchoita) en el año 2008: estima-

ción mediante el método de producción diaria

de huevos. Inf Téc Of INIDEP Nº 29/2009. 19

p.

PINKAS LM, OLIPHANT S, IVERSON ILK. 1971.

Food habits of albacore, bluefin tuna and

bonito in Californian waters. Calif Fish Game.

152: 1-105.

RICO MR. 2010. Pesquería de lenguados en el

ecosistema costero bonaerense al norte de 39º

S. Frente Marít. 21: 129-135.

RICO MR, LAGOS AN. 2010. Lenguados del siste-

ma costero bonaerense. Herramientas para la

identificación de especies. Inf Téc Of INIDEP

Nº 58/2010. 15 p.

RICO MR, PERROTTA RG. 2009. Análisis de la

captura y el esfuerzo de pesca aplicado al

grupo lenguados en el área costera bonaeren-

se. Período 1981-2005. Inf Téc Of INIDEP Nº

35/2009. 22 p.

RIESTRA MC. 2010. Edad, crecimiento e influen-

cia del ambiente en la distribución de Para-

lichthys patagonicus en el Sistema Costero del

Atlántico Sudoccidental (34°-41° S) [tesis de

grado]. Mar del Plata: Facultad de Ciencias

Exactas y Naturales, Universidad Nacional de

Mar del Plata. 55 p.

RIESTRA MC, DÍAZ DE ASTARLOA JM, VIEIRA JP,

BURATTI CC, IRIGOYEN AJ, LANDAETA M,

79

TROCCOLI ET AL.: DIET COMPOSITION OF PATAGONIAN FLOUNDER

HÜNE M. 2020. Paralichthys patagonicus. The

IUCN Red List of Threatened Species 2020:

e.T195089A165017727.

RODRÍGUEZ D, RIVERO L, BASTIDA R. 2002. Feed-

ing ecology of the Franciscana (Pontoporia

blainvillei) in marine and estuarine waters of

Argentina. LAJAM. 1: 77-94.

SÁNCHEZ MF. 2002. Alimentación de la merluza

(Merluccius hubbsi) en la Zona Común de

Pesca Argentino-Uruguaya entre los años

1995 y 2000. Inf Téc Int-DNI INIDEP Nº

118/2002. 14 p.

SÁNCHEZ MF, DÍAZ DE ASTARLOA JM. 1999. Ali-

mentación del lenguado Paralichthys patago-

nicus. 8º COLACMAR, Congreso Latinoame-

ricano Ciencias del Mar. Trujillo, Perú. p. 186-

188.

SCHARF FS, JUANES F, ROUNTREE RA. 2000. Pred-

ator size-prey size relationships of marine fish

predators: interespecific variation and effects

of ontogeny and body size trophic-niche

breadth. Mar Ecol Prog Ser. 208: 229-248.

SILVA M, BASTIDA R, DARRIEU C. 2000. Dieta de

la gaviota cocinera (Larus dominicanus) en

zonas costeras de la provincia de Buenos

Aires, Argentina. Ornit Neot. 11: 331-339.

STERNER RW, BAJPAI A, ADAMS T. 1997. The

enigma of food chain length: absence of theo-

retical evidence for dynamic constraints. Ecol-

ogy. 78: 2258-2262.

STONER AW, LIVINGSTON RJ. 1984. Ontogenetic

patterns in diet and feeding morphology in

sympatric sparid fishes from seagrass mead-

ows. Copeia. 1984 (1): 174-187.

SUAREZ AA, SANFELICE D, CASSINI MH, CAPPOZ-

ZO HL. 2005. Composition and seasonal vari-

ation in the diet of the South American Sea

Lion (Otaria flavecens) from Quequén,

Argentina. LAJAM. 4 (2): 163-174.

VÖGLER R, MILESSI AC, DUARTE LO. 2009.

Changes in trophic level of Squatina guggen-

heim with increasing body length: relation-

ships with type, size and trophic level of its

prey. Environ Biol Fish. 84: 41-52.

VÖGLER R, MILESSI AC, QUIÑONES RA. 2003.

Trophic ecology of Squatina guggenheim on

the continental shelf off Uruguay and northern

Argentina. J Fish Biol. 62: 1254-1267.

WAESSLE JA, LASTA C, FAVERO M. 2003. Otolith

morphology and body size relationships for

juvenile Sciaenidae in the Río de la Plata Estu-

ary (35-36°S). Sci Mar. 67: 233-240.

80 MARINE AND FISHERY SCIENCES 35 (1): 67-80 (2022)