Introduction

Pughead deformity is an abnormal osteological condition that results in the aberration of the maxilla, premaxilla, or infraorbital bones, with variable degrees of severity (Hickey, 1977). Pughead anomaly is an infrequent occurrence in the wild, particularly in large estuarine systems (Berra and Au, 1981). Higher incidences of pughead cases of abnormality were revealed from more polluted waters (Slooff, 1982).

The term saddleback syndrome was first proposed by Tave et al. (1983) for an abnormality cases of different degrees of lack of dorsal fin in tilapia Sarotherodon aureus. Since then, this deformity has associated with severe anomaly of the dorsal profile of the fish resulted from deformed dorsal fin pterygiophores. It has been reported from fish species in the wild around the world (Jawad and Al-Mamry, 2012; Diggles, 2013; Boglione et al., 2013; Pollock, 2015).

Common pandora is a marine species living in benthopelagic habitat at depth down to 300 m (Bauchot and Hureau, 1986). It distributed in the eastern Atlantic Ocean and the Mediterranean Sea (Sanches, 1991). Individuals of this species prefer deep water during winter time. It is omnivorous, but mainly feed on benthic invertebrates and small fishes. Sex interchange is possible as females become males in their 3^rd year of life (Bauchot and Hureau, 1986; Froese and Pauly, 2017).

As far as the authors are concerned, the pughead and saddleback syndrome anomalies have not reported for this species previously. Therefore, this report is the first to document the two cases of abnormalities in P. erythrinus and in the Turkish waters.

1 Materials and Methods

On 1^st July 2016 one specimen of P. erythrinus showing pughead and saddleback syndrome deformities was caught by a bottom trawl (44 mm mesh size in cod-end) at depth of 60 m from Gerence Bay, off Çeşme, Izmir (38°25’N-26°16’E). A normal specimen was also obtained from the same fishing lot used for comparison (Figure 1A; Figure 1B). The specimens were fixed in 70% ethanol and deposited in the fish collection of the Ege University, Fisheries Faculty (ESFM-PIS/2016-10). The skeleton of both normal and abnormal specimens were examined by x-ray and measurements were recorded to the nearest millimetre.

Figure 1 Pagellus erythrinus; A: normal, 192 mm total length; B: abnormal, 246 mm total length

2 Results

2.1 Pughead case

The pug-headed specimen had a 192 mm total length, 153 mm standard length, 18 mm preorbital length, 33 mm postorbital length, 15 mm eye diameter, 47 mm head length and 94 mm predorsal fin length. This specimen is compared to normal fish having 246 mm total length, 202 mm standard length, 21 mm preorbital length, 24 mm postorbital length and 23 and 68 mm head length.

Externally, the abnormal specimen was shown to have only short neurocranium with normal jaws and mouth was closed, which means that the deformity has not affected the mechanism of opening and shutting the mouth (Figure 1A; Figure 1B).

The osteological deformity was compared with the normal specimen. Internally, the vomer and parasphenoid were shortened, and displacement and/or curvature of the nasals, frontals, vomer, and palatines were observed. Premaxilla is normal and maxilla is reduced in size. Teeth are present, but those located posteriorly on the upper jaw appeared to be deformed in comparison with those of the normal specimen. The forehead is retracted backward and the angle “A 2” between the line passing at the anterior edge of the eye and that passing between the nape and the tip of the mouth is 23°, while that of the normal specimen “A1” is 46°. In comparison with the vertebral column of the normal specimen, the contour of the 1^st abdominal vertebra was changed in having concave and convex upper and lower sides respectively and curved and buldging outside anterior and posterior sides respectively (Figure 2A; Figure 2B).

2.2 Saddleback syndrome case

3 Discussion

Hickey et al. (1977) described 4 stages of pughead deformity in teleostean fishes: normal, primary, secondary and tertiary. The present case of pughead anomaly in P. erythrinus represents the secondary of Hickey et al. (1977) system. Unlike other cases of pughead reported from several fish species (AL-Hassan, 1988; Jawad and Hosie, 2007; Jawad et al., 2014), the present case looks mild as the mouth is closed and the fish can avoid several risks as this closure.

Although not much of bone elements were lost from the skull of P. erythrinus, but the deformation in the bones at the anterior part of the cranium could consider this a severe case. The distorted 1^st abdominal vertebra shown in the x-ray might have been a result of the displacement of the posterior part of the skull, which in turn has a direct effect on the brain. Since the preorbital area was reduced very much and the nasal openings were affected in this specimen, the nasal organs and probably the olfactory nerve were lost too. Dissection of the skull to study the brain is required to reveal the damages that might occurred to the brain due to the pughead deformity. Similar postcranial skeletal deformity as a result of pughead was reported in the historical case observed by Yiung (1901) on small specimen of salmon species obtained from France.

Due to the natural closure of the mouth, the suggestions made by Hickey (1977) in that fishes with pughead deformity may fail the ability to breath and feed, which in turn became unable to compete for obtaining food are not apply to the present specimen. It is also seems that this deformity did not reduced survival potential and the body of the deformed fish is robust inferring the ability to have a quick move when potential predators appear.

The causes of the observed pughead anomaly in the specimen examined are unknown, but they probably arise during early development (Cobcroft et al., 2001). The survival rate of abnormal fish, especially during the early ontological stages in the wild, is unknown (Bueno et al., 2015). To determine the overall incidence and effect of these abnormalities, survival throughout development, larva through adult, must be considered.

In all cases reporting saddleback syndrome, the dorsal fin in its both parts, spinous and soft, is involved in deformity, where these elements showed missing at different levels (Cobcroft and Battaglene, 2013). In the present specimen, the saddleback is appeared to affect the anterior part, a case which agrees with the results obtained for other fish species (Tave et al., 1983).

Both the pughead and saddleback syndrome deformities might resulted from an unhealthy environment, with contaminants originated from anthropogenic activities that has an influence on early life history stages of fish directly (Browder et al., 1993; Gagnon and Rawson, 2009). On the other hand, and for saddleback syndrome, the predation by other fish species and injuries by sea birds on fish specimens in the studied area during early life history remains possible.

Future research is required to study the variability of both pughead and saddleback syndrome in both juvenile and adult commercial fish species in different locations and years, taking into consideration the mortalities that related to these two anomalies.

Authors’ contributions

All authors have contributed equally toward the publication of this paper.

Acknowledgments

We would like to thank the Ege University Faculty of Fisheries, Turkey for giving us the opportunity to examine and study the deformed fish specimens. Our thanks are also due to Sergey Bogorodsky of Station of Naturalists, Omsk, Russia and Ronald Fricke of Staatliches Museum für Naturkunde, Rosenstein, Germany, for identification of the species.

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