First Record of the Arabian Barracuda Sphyraena arabiansis (Sphyraenidae) from Korean Waters

Abstract

This study reports the first records of Sphyraena arabiansis in the Korean waters. The two specimens were collected from the coastal waters of Yeosu (1164 mm TL) and Jeju Island (1187 mm TL), Korea, on 31 July and 24 October 2025, respectively. This species is characterized by the posterior end of the upper jaw not extending vertically below the eye, the lateral line curving anterior to the first dorsal fin, the lower part of the branchiostegal membrane being whitish, dark transverse bands on the upper side of the body crossing the lateral line but not reaching the abdomen, no black spots on the body side, 118 and 121 lateral line scales, and 14 scales below the lateral line. To confirm the accuracy of species identification, the mitochondrial DNA cytochrome c oxidase subunit I sequences were obtained from the samples and compared with those of seven sphyraenid species recorded in the NCBI GenBank database. As a result, they matched well with S. arabiansis but differed from those of S. barracuda. The new Korean name, “Jjal-beun-ip-keun-kko-chi-go-gi,” is proposed for the species.

1. Introduction

The family Sphyraenidae is widely distributed in tropical and subtropical seas worldwide and consists of a single genus, Sphyraena, which includes 29 valid extant species [1]. Members of this family are large, predatory fish found in coastal and offshore waters. They are characterized by an elongated fusiform body, long pointed head, large mouth equipped with prominent canine teeth, two widely separated dorsal fins, and forked caudal fin [2]. In addition, the species are classified into three groups according to their gill raker counts (0, 1, or 2 rakers) [3]. Sixteen species in this family have been reported in the Indo-Pacific Ocean [1,3], among which only three species, Sphyraena pinguis, S. japonica, and S. obtusata, have been reliably documented in the waters of Korea [4]. Family Sphyraenidae was placed in Perciformes by Nelson [5] and in Istiophoriromes by Nelson [2]. Subsequent molecular phylogenetic studies have considered this family to be a member of Carangaria [6] or Carangiformes [7].

Recently, two large specimens of barracuda were collected using a set net in the coastal waters of Yeosu and Jeju Island, Korea, in July and October 2025. The specimens were identified as Sphyraena arabiansis Abdussamad and Retheesh, 2015, [8], based on their morphological characteristics. In addition, nucleotide sequencing of the mitochondrial cytochrome c oxidase subunit I (mtDNA COI) gene was performed to confirm the accuracy of species identification. The morphological features of S. arabiansis have not been reported in Korea. Sphyraena arabiansis was previously considered conspecific with Sphyraena barracuda because of their high degree of morphological similarity. However, Abdussamad et al. [8] demonstrated that these two species are morphologically and genetically distinct. Since then, S. arabiansis has been reported in Pakistan [9], New Caledonia, and southern Japan [10].

This study aimed to report the first occurrence of S. arabiansis in Korea and to provide the morphological description and DNA barcoding data of the collected two specimens as part of the Korean fish fauna.

2. Materials and Methods

2.1. Sampling Data and Measuremensts

On 31 July 2025 and 24 October 2025, two specimens of barracuda were collected by a set net, one from the coastal waters of Yeosu (34.5721° N, 127.8047° E) and the other from Jeju Island (33.4003° N, 126.2141° E), Korea, respectively, at a depth of approximately 30 m (Figure 1). The specimen collected from Yeosu measured 1164 mm in total length and weighed 7.65 kg (Figure 2), whereas the individual from Jeju Island measured 1187 mm in total length and weighed 8.45 kg. The corresponding surface water temperatures were recorded as 27.0 °C and 25.3 °C, respectively. The collected two specimens were transported to the laboratory of the East Sea Fisheries Research Institute, where they were photographed 24 h after being collected.

Counts and measurements were performed as described by Doiuchi and Nakabo [11]. Morphometric measurements were taken to the nearest 0.1 mm using digital Vernier calipers (Mitutoyo Corp., Kawasaki, Kanagawa, Japan) and a fish scale plate (Daehan Science Co., Seoul, Republic of Korea). The body weight was measured using an electronic balance to the second decimal place in kilograms. The specimens were initially fixed in 10% formalin for 48 h and subsequently transferred to 70% ethanol for preservation. They were deposited (Yeosu: ESFRI-1; Jeju Island: ESFRI-2) at the East Sea Fisheries Research Institute of the National Institute of Fisheries Science (NIFS), Korea.

2.2. Molecular Analysis

Total genomic DNA was extracted from muscle tissue using a commercial DNA extraction kit (Bioneer Corp., Daejeon, Republic of Korea). PCR amplification of the mtDNA COI gene was conducted using universal primers (forward primer: VF2_t1, reverse primer: FishR2_t1) according to the manufacturer’s instructions [12]. PCR was performed using Takara Premix Ex taq version2.0 (Takara Bio Inc., Kusatsu, Shiga, Japan) according to manufacturer’s instructions. 50 µL reaction comprised 100 ng of template DNA, 25 µL of Takara premix taq, 2.5 µL (0.4 µM) of each primer. PCR conditions were as follows: 94 °C for 2 min, 35 cycles of 94 °C for 30 s, 52 °C for 45 s, and 72 °C for 1 min, with a final extension at 72 °C for 7 min. Amplified PCR products were purified using a PCR purification kit (Bioneer Corp., Daejeon, Republic of Korea). Purified PCR products were treated with an ABI Prism BigDye Terminator Cycle Sequencing Ready Reaction kit (Applied Biosystems, Foster City, CA, USA). The amplified products were sequenced in both forward and reverse directions to obtain a consensus sequence of approximately 630 bp. The mtDNA COI sequences obtained from the two specimens (Yeosu: PX415422; Jeju Island: PX492412) were deposited in the NCBI (National Center for Biotechnology Information) GenBank database.

To identify species and construct a molecular phylogenetic tree of the genus Sphyraena in the Indo-Pacific, mtDNA COI sequences of seven Sphyraena species were retrieved from the GenBank database. Scomber japonicus (EF433288) was used as the outgroup. The references obtained from NCBI included Sphyraena arabiansis (KF590625, KF590626), S. barracuda (MH331872, KH119506), S. forsteri (OP024182), S. quenie (FKP194703), S. japonica (AP012501), S. pinguis (GU673885), and S. obtusata (KU499681). All sequences, including those generated in this study, were aligned using ClustalW, implemented in MEGA 12 software [13]. The aligned sequences were 615 bp in length.

Pairwise nucleotide differences between sequences were calculated using the uncorrected p-distance (fraction of sites different between two sequences) [14], and phylogenetic trees were constructed using the Maximum Likelihood [15] and neighbor-joining method [16]. Node support was assessed with 1000 bootstrap replications. All molecular analyses were performed using MEGA version 12 [13].

3. Results

3.1. Morphological Characteristics

Counts and measurements are presented in

Table 1. Comparison of meristic counts between present and previous studies on Sphyraena arabiansis.

Meristic Characters	Present Study	Abdussamad et al. [8] (Holotype)	Manzoor et al. [9]	Morishita et al. [10]
No. of specimens	2	1	1	5
Counts
Dorsal fin rays	V-I, 9	V-I, 10	V-I, 10	V-I, 9
Pectoral fin rays	ii, 12	14	14	ii, 12
Pelvic fin rays	I, 5	I, 5	I, 5	I, 5
Anal fin rays	II, 8	I, 9	I, 9	II, 8
Lateral line scales	118, 121	120	120	118–126
Scales above lateral line	11	11	11	10–11
Scales below lateral line	14	13	13	13–14
Gill rakers	0	0	0	0
Branchiostegal rays	7	7	7	-

and

Table 2. Comparison of morphometric measurements between present and previous studies on Sphyraena arabiansis.

Morphometric Characters	Present Study	Abdussamad et al. [8] (Holotype)	Manzoor et al. [9]	Morishita et al. [10]
No. of specimens	2	1	1	5
Total length (mm)	1164–1187	-	-	-
Fork length (mm)	1120–1150	950	950	-
Standard length (mm)	1053–1086	850	850	648.5–1162.9
In % standard length
Head length	25.9	27.53	25.5	26.1–29.1
Body depth at pelvic fin insertion	12.5–14.9	13.05	13.5	12.7–15.2
Body depth at 2nd dorsal fin origin	12.6–13.3	12.66	11.0	12.4–14.0
1st dorsal fin base length	7.2–7.3	6.34	7.8	6.0–6.8
2nd dorsal fin base length	8.4–8.5	8.99	9.3	8.5–9.7
Anal fin base length	7.2–7.5	8.13	7.3	7.4–8.5
Pre-dorsal fin length	37.4–38.5	41.18	37.0	38.7–40.9
Pre-2nd dorsal fin length	66.8–67.9	69.41	62.0	68.8–71.2
Prepectoral fin length	26.0–27.1	28.24	25.0	27.3–29.3
Pre-pelvic fin length	32.6–35.1	35.41	31.5	34.7–36.8
Pre-anal fin length	69.0–70.2	70.59	63.2	71.2–72.3
1st dorsal fin height	6.7–7.2	7.75	8.0	7.1–8.0
2nd dorsal fin height	8.8–8.9	10.59	9.2	7.8–10.1
Pectoral fin length	10.2–10.4	10.94	9.5	10.4–11.5
Pelvic fin length	7.0	8.29	7.5	6.7–8.8
Distance from origin of first dorsal to origin of second dorsal fin	29.4–29.9	-	-	28.3–31.1
Distance from pelvic fin to anal fin	34.9–36.0	-	-	36.3–37.6
Snout length	11.0–11.5	13.29	11.91	12.1–12.9
Orbital diameter	2.7	3.06	2.9	2.8–3.3
Orbital depth	2.4–2.6	-	-	2.6–3.3
Interorbital length	6.0–6.6	5.36	7.2	6.4–7.0
Upper jaw length	11.4–12.6	12.00	10.5	12.2–12.8
Postorbital length	12.4–12.6	11.53	11.5	10.7–13.2
Caudal peduncle length	17.3–17.8	19.53	19.0	20.1–20.8
Caudal peduncle depth	6.0	6.06	6.0	6.0–6.8
Caudal peduncle width	3.7–4.2	3.61	3.5	-
Snout to anus length	64.3–70.2	67.06	60.0	-
Upper caudal fin length	18.0–18.3	-	-	18.6–20.7
Lower caudal fin length	16.2–17.0	-	-	16.5–19.2

, respectively. Body elongated and slightly compressed; body and head covered with cycloid scales, except for the jaw, snout, and interorbital region; lateral line slightly curved until the first dorsal fin and nearly straight thereafter; dorsal profile of the body rises gently from the lower jaw to the origin of the second dorsal fin and then slopes gently downward toward the caudal fin base; ventral profile lowering from the lower jaw tip to the origin of the pelvic fin, therefore gently lowering to the origin of the anal fin, subsequently rising to the lowermost point of the caudal fin base; head large, 25.9% of standard length, interorbital space almost flat; two dorsal fins, origin of the first dorsal fin started posterior to the pelvic fins; origin of the second fin is situated just anterior to the origin of the anal fin, and the origin of the anal fin lies directly on the third soft ray of the second dorsal fin; posterior tip of the pectoral fin pointed, extending beyond the origin of the pelvic fin; pelvic fin short; snout pointed, tip of lower jaw projecting anterior to upper jaw; posterior tip of the maxilla not extending vertically below the anterior margin of the eye (Figure 3A), upper jaw with two rows of numerous teeth (Figure 3B); two pairs of large, recurved, and sharp canine teeth on the front of the upper jaw; seven to eight pairs of pointed canines posteriorly on the inner side; and 17–18 small teeth on the outer side; upper jaw with a single row of numerous sharp canine teeth; caudal fin widely forked with sharp paired central lobes of the caudal fin more pointed (Figure 3C), and no gill rakers on upper and lower gill arches (Figure 3D).

In fresh condition, the dorsal part of the body is dark bluish, while the ventral part is silvery white without distinct black spots on the body; the lower portion of the branchiostegal membrane behind the opercle is white; the body bears approximately 16 indistinct dark transverse bands crossing the lateral line, but these bands do not extend ventrally to the lower abdomen; the posterior rays of the anal and second dorsal fin, as well as the posterior margins of both caudal fin lobes, are whitish, while the remaining fins are blackish; the anterior portion of the pectoral fin is yellowish-brown.

3.2. Distribution

Sphyraena arabiansis was originally described from the Lakshadweep Islands in the Arabian Sea, India [5]. It has since been reported in Pakistan [6], southern Japan, and New Caledonia [7] (Figure 1). This record represents the first occurrence of this species in Korean waters.

3.3. Molecular Identification

The mtDNA COI gene sequence obtained from the two specimens (PX415422, PX492412) showed 99.8–100.0% similarity to S. arabiansis (KF590625, KF590626) sequences available in the NCBI GenBank database. However, the p-distance between the Korean specimens and S. barracuda sequences exceeded 11.7–11.9%, supporting its identification as S. arabiansis. The average interspecies distance among the seven Sphyraena species was 13.8 ± 1.3%.

A Maximum likelihood phylogenetic tree clearly placed the Korean specimens within the S. arabiansis clade, separate from S. barracuda and other Sphyraena species, validating the molecular distinctiveness of this taxon (Figure 4).

4. Discussion

The present specimens were characterized by the following features: the posterior end of the upper jaw did not extend vertically below the eye; the lateral line curved anterior to the first dorsal fin; the lower part of the branchiostegal membrane behind the operculum was whitish; the dark transverse bands on the upper side of the body crossed the lateral line but did not reach the abdomen; there were no black spots on the body side; there were 118 and 121 lateral line scales and 14 scales below the lateral line. The morphological characteristics of the specimens were compared with those of previous studies [8,9,10], which revealed that all morphological characteristics examined clearly fit the previous species descriptions of S. arabiansis (Table 1). Additionally, molecular identification was performed by analyzing the mtDNA COI sequences for accurate identification of the collected two specimens. The results indicated that the COI sequences of the present specimens were almost identical (99.8–100%) to those of S. arabiansis obtained from NCBI but were different from those of S. barracuda. Thus, we identified our specimens as S. arabiansis based on both morphological and molecular characteristics.

The present study documents the first confirmed occurrence of Sphyraena arabiansis in Korean waters. Its appearance may be related to rising sea temperature associated with climate change [17], but other environmental factors such as shifts in oceanic currents and range expansion of the species may also have contributed. In recent years, the number of previously unrecorded subtropical and tropical fish species in Korean waters has increased, and this trend is expected to continue with the appearance of additional unrecorded species [4].

Sphyraena arabiansis morphologically resembles S. barracuda in the Indo-Pacific Ocean. The former is distinguishable from the latter by the following characteristics: the posterior end of the maxilla (not extending to the eye vs. extending to the eye for S. barracuda), color of the branchiostegal membrane (white vs. black), body spots (none vs. presence), location of body bars (crossing lateral line vs. not crossing lateral line), shape of paired central lobe of caudal fin (more pointed vs. less pointed), shape of lateral line (arched before first dorsal fin vs. no arched), pored lateral line scales (113–122 vs. 76–82), scales above lateral line (10–11 vs. 9–10), scales below lateral line (13–15 vs. 10–11), middle preopercular scale rows (14–15 vs. 11–13) and lower preopercular scale rows (18–21 vs. 13–16) [8,9,10].

Finally, this species has not yet been assigned a name in Korean. Considering that this species has a relatively smaller mouth than S. barracuda, we propose “Jjal-beun-ip-keun-kko-chi-go-gi” as its new Korean name. In addition, continuous monitoring is necessary to identify newly occurring fish species on the Korean Peninsula.

5. Conclusions

This study reports the first confirmed occurrence of Sphyraena arabiansis in Korean waters. The occurrences of S. arabiansis are presumed to have been induced by ocean warming associated with climate change. Furthermore, the morphological characteristics and DNA barcoding data presented in this study provide valuable references for future taxonomic identification and molecular phylogenetic analyses of this species in other regions.