Dorsal Fin Spines Research Articles

Direct Ageing and Growth using Dorsal Fin Spines of Bluefin Tuna Thunnus thynnus (Scombridae) Reared in Sea Cages and a Comparison with Wild Populations

The main objectives of this study were to estimate the age and growth of reared Atlantic bluefin tuna and to reveal possible differences in growth between reared and wild specimens. A total of 806 specimens, ranging from 102 to 284 cm in length, were sampled from a Greek tuna farm in the Mediterranean Sea. The first spine of the first dorsal fin was used to estimate the age. Estimated ages ranged from 3 to 20 years, and the reproducibility of the ageing method was high. The proportion of the mean number of missing annuli per age due to vascularization ranged from 27.8 to 40.0%, with an average loss of 33.5%. No significant differences in the number of missing annuli were observed between 6–month and 18–month reared specimens of the same age group. The von Bertalanffy growth model was fitted a) to mean FL-at-age data and b) to mean RW-at-age data, and the growth equations found were: Lt = 296.6[1 – e(−0.114) (t + 1.026)] and Wt = 591.6[1 – e(−0.100)(t + 1.755)]3. Our results showed that the rearing process accelerates the growth of the Atlantic bluefin tuna and this was also evident in the calcified structure. In comparison with previous studies of growth in wild bluefin tuna from the Mediterranean Sea, mean weights at age of the reared fish were higher than those from wild fish in all age groups and lengths at age of the reared bluefin tuna were higher in younger fish, up to 6 years old.

A Juvenile of Rhinopias cf. argoliba (Scorpaenidae) from the Tropical Western Pacific

A juvenile of Rhinopias cf. argoliba 28 mm SL collected in the western part of the Pacific Ocean eastward of the Philippines is described. It is characterized by an incomplete metamorphosis with some larval characters retained such as the developed spination and relatively straight dorsal contour of the head, absence of the scales and the branched fin rays (except in pelvic fins), and a long penultimate dorsal-fin spine. Comparison of this juvenile with juveniles of R. aphanes 11–22 mm SL reveals the diagnostic importance of the pigmentation of the pectoral fin which disappears in the adult fishes. A possible synonymy of the genera Rhinopias and Pogonoscorpius was repeatedly supposed by the former authors. The poorly-known Pogonoscorpius sechellensis retains the features characteristic for the species of Rhinopias from the earliest ontogenetic stages only, and probably represents a neotenic species of the latter genus.

Length-Weight Relationship and Condition Factors of Sarotherodon galilaeus (Linnaeus, 1758) from Nguru-Gashua Wetlands, Northeast Nigeria.

This study examined the length-weight relation and condition factor of Sarotherodon galilaeus (Linnaeus, 1758) from Nguru-Gashua wetlands, Northeast, Nigeria. A total of 375 specimens were purchased from local fishermen at the designated landing sites for six months. Results of morphometric characteristics showed that the body weight of male S. galilaeus ranged from 127-770 g (601.7±28.01) and females ranged from 272 – 704 g (711.3±38.12). Meristic features show that spinous anal fin rays were constant in both sexes while soft dorsal fin rays, pectoral fin rays, soft anal fin rays and spinous dorsal fin rays had the same range for both sexes. The sex ratio (1:2.18) observed in this study tends to favour male species but contrasts with the general assumption of a sex ratio of 1:1. Mean coefficient of determination was 0.89±0.07 and 0.87±0.07 for male and female S. galilaeus respectively indicating that length-weight relationship model is very reliable. This implies that the change in weight of the sampled fish was caused by 88.52% and 86.68% change in length of male and female S. galilaeus respectively. It was further revealed that both sexes (b = 2.86±0.18 and 2.88±0.35) had negative allometric growth patterns. The wetland's environmental conditions were within a tolerable range for cichlids.

Direct Ageing and Growth using Dorsal Fin Spines of Bluefin Tuna Thunnus thynnus (Scombridae) Reared in Sea Cages and a Comparison with Wild Populations

Direct Ageing and Growth using Dorsal Fin Spines of Bluefin Tuna Thunnus thynnus (Scombridae) Reared in Sea Cages and a Comparison with Wild Populations

A new species of Fusigobius (Teleostei: Gobiidae) from the Red Sea and Gulf of Aden

The gobiid species, Fusigobius humerosus sp. nov., is described based on 12 type and 18 non-type specimens collected from the Red Sea and Gulf of Aden. The new species can be distinguished from congeners by a combination of meristic and morphometric characters. The new species was formerly misidentified with F. humeralis: both are characterised by a semitranslucent body; head and body with numerous small dusky orange-yellow spots; a round black spot in humeral region just above base of pectoral fin; and a black spot subequal to pupil diameter at midbase of the caudal fin. However, Fusigobius humerosus sp. nov. differs from F. humeralis by scales on side of nape not extending forward to above posterior margin of preopercle (vs. scales variably extending forward to between above posterior preopercular margin and orbit); first dorsal-fin spine longest (vs. second and third dorsal-fin spines longest); shorter upper jaw; shorter anal-fin spine; and posterior nostril about halfway between orbit and anterior nostril (vs. posterior nostril closer to orbit). The most complete description of the genus Fusigobius is provided. In phylogenetic analyses of publicly available sequences of the barcoding portion of the mitochondrial cytochrome oxidase subunit I (COI) gene, sequences derived from the new species form a separate and well-divergent monophyletic lineage. The resulting COI gene tree further suggests that the new Fusigobius species is phylogenetically most closely related to F. humeralis which forms its sister species in the maximum likelihood tree. Molecular species delimitation of available Fusigobius COI barcodes shows that 19 or 20 hypothetical divergent evolutionary lineages can be deduced depending on the analytical approach (ABGD = 19 and bPTP = 20), indicating a potentially higher taxonomic richness than the presently acknowledged 11 valid species. However, the assignment of available species names for some lineages remains uncertain, highlighting the need for an additional integrative taxonomic research on this genus.

Description of a New Deep-Water Eulophiid Fish (Perciformes: Zoarcoidei) from Japan

The genus Eulophias, which is an enigmatic group of the suborder Zoarcoidei, previously comprised two rare species: Eulophias tanneri Smith, 1902 (type species and a senior synonym of Eulophias owashii Okada and Suzuki, 1954) and Eulophias koreanus Kwun and Kim, 2012. Here we describe a new species, Eulophias spinosior, based on 71 specimens (94.9–182.3 mm in standard length, SL) collected from the upper slope of the northwestern Pacific off southern Japan at depths of 257–555 m. It readily differs from its two congeners in having 133–143 dorsal-fin spines, 109–116 anal-fin soft rays, 5–6 pectoral-fin rays, and 146–156 total vertebrae, and in lacking a dark band posterior to the eye and a series of dark blotches midlaterally on the trunk and tail. Regarding bathymetric distribution, the new species occurs much deeper than E. koreanus and E. tanneri. Eulophias spinosior, new species, is sexually dimorphic, with males having large, stout, modified canines at the tips of the premaxillary and dentary (vs. only slightly enlarged in females). Dentition of males also differs from that of females in that most teeth are uniserially arranged in each jaw (vs. distinct two rows anteriorly).

Description and phylogenetic position of a new species of Rhyacoglanis (Siluriformes: Pseudopimelodidae) from the Jamanxim River basin

Abstract In this study, a new species of Rhyacoglanis is described from the Jamanxim River basin, Tapajós River basin. The new species differs from congeners based on the combination of the following diagnostic characters: two oblique dark bands formed by an agglomerate of melanophores on the predorsal region; dorsal confluence between the dark subdorsal and subadipose bands in large juveniles and adults; ventral confluence between the dark subadipose and caudal peduncle bands; body without conspicuous dark brown spots; complete dark band on caudal peduncle; body with three dark bands; a thin dark caudal-fin band; pectoral-fin spine with anterior serrae distributed along the entire margin; the posterior tip of the post-cleithral process reaching vertical through the base of the dorsal-fin spine; and hypural 5 free of hypural 3 and 4 and pointed caudal-fin lobes. Additionally, our molecular phylogenetic results using ultraconserved elements (UCEs) corroborate the new species as Rhyacoglanis and sister to an undescribed species of Rhyacoglanis from the Xingu River basin. Moreover, as pointed out in previous studies, we confirm Cruciglanis as a sister group to Pseudopimelodus plus Rhyacoglanis.

Chemical signatures in fin spine edge of Atlantic bluefin tuna (Thunnus thynnus) can serve as habitat markers of geographically distinct marine environments

Chemical fingerprints in otoliths are commonly used as natural habitat markers in fishes. Alternatively, the first dorsal fin spine can provide valuable chemical information and may be more suitable for studying (i) endangered fish species that cannot be sacrificed for their otoliths or (ii) fishes for which otoliths might not be available because of management or commercial reasons. Here, we studied multi-element chemistry of fin spine edges collected from Atlantic bluefin tuna (ABFT; Thunnus thynnus) (Linnaeus, 1758) to investigate the utility of the fin spine edge as a natural habitat marker. We determined stable isotopic δ18O and δ13C ratios, as well as concentrations of the tracer elements Mg, Mn, Li, Ba, and Sr, at the edge of ABFT fin spines, and then we used these measures to discriminate ABFT individuals among capture regions (i.e., the eastern Atlantic Ocean or Mediterranean Sea). Isotope ratios and tracer element concentrations, and especially a combined multi-element approach, were able to effectively discriminate individuals by capture region. The Mg, Mn, Li, and δ18O concentrations were the strongest variables driving this discrimination. Overall, our results demonstrate that chemical signatures are consistently retained in the ABFT fin spine edge and support the use of fin spine edges for discerning habitat use. The fin spine chemistry as a minimally invasive sampling method, combined with otolith chemistry, genetic markers, and tagging efforts can help us to reconstruct fish movements, providing a deeper understanding of the spatial population dynamics of this iconic fish species.

Diversity of gobioid fishes in the late middle Miocene of northern Moldova, Eastern Paratethys—Part II: description of †Moldavigobius helenae gen. et sp. nov.

The middle Miocene (upper Serravallian, lower Volhynian) deposits at Karpov Yar near Naslavcea, northern Moldova, are among the few settings in which fossil fish are preserved with otoliths in situ. Here, we describe the new gobiid †Moldavigobius helenae gen. et sp. nov. from this locality. The taxon is characterized by small size (up to 34.2 mm SL), a compact body (body depth 17–21% SL), a fan-shaped caudal fin, large ctenoid scales (< 30 scales in the longitudinal row) and nearly square otoliths (sagittae) with a slender, shoe sole-shaped sulcus. It has 27 vertebrae, six spines in the first dorsal fin, one spine and 11 soft rays in both the second dorsal and the anal fin, 15–17 pectoral-fin rays, and 17 (9/8) segmented caudal-fin rays. The meristic characters of †Moldavigobius gen. nov., together with its sagitta shape, suggest a relationship with Lesueurigobius Whitley, 1950, but its fan-shaped caudal fin and the unique sulcus contour of the otoliths preclude its attribution to that genus. In addition, we re-assign an otolith-based species previously described as Knipowitschia suavis Schwarzhans, 2014 as a second member of †Moldavigobius gen. nov. Accordingly, †Moldavigobius gen. nov. was represented by at least two species in the Serravallian of the Eastern Paratethys (†M. helenae gen. et sp. nov., †M. suavis nov. comb.). Moreover, †M. suavis is also known from the Serravallian ichthyofauna of the SE Mediterranean. †Moldavigobius gen. nov. thus demonstrates the key role of fossil skeletal material with otoliths in elucidating the ancient diversity of the Gobioidei.

Redescription of Lophiodes lugubris (Alcock, 1894), with the largest record of Lophiodes triradiatus (Lloyd, 1909) from the South China Sea (Lophiiformes: Lophiidae)

A rare lophiid anglerfish species, Lophiodes lugubris, is redescribed on the basis of two syntypes and non-types. It is unique in having only 4 dorsal-fin spines, among the congeners. Examination of specimens reveals this species is widespread in the Indian Ocean and a specimen newly collected from off Dongsha Island represents the first record of the South China Sea, as well as the Pacific Ocean. A largest record specimen of Lophiodes triradiatus known to date is also documented. Comments on the morphology of sagittal otoliths taken from Taiwanese lophiids are provided.

Reliable growth estimation from mark–recapture tagging data in elasmobranchs

The somatic growth of individuals governs many aspects of a species’ life history and is an important parameter in the assessment of populations. Population growth parameters are typically derived by relating the length of individuals to their age, with ages commonly estimated from growth bands formed in calcified structures such as the vertebrae or dorsal fin spines. However, routinely utilized vertebrae aging methods may not be reliable for many elasmobranchs (sharks, rays and skates), motivating alternative approaches. This study evaluates the performance of seven techniques that estimate von Bertalanffy growth parameters from mark-recapture tagging data. Evaluation of the performance was done by applying each estimation technique to: 1) simulated error-free mark-recapture tagging data and comparing the estimated versus known simulated growth parameters; 2) simulated mark-recapture data considering individual growth variability, measurement error, different length-at-capture distributions, as well as different sample sizes and comparing the estimated versus known simulated growth parameters; and 3) mark-recapture data of 14 North Atlantic elasmobranch stocks and discussing the estimated growth parameters with respect to biological plausibility and conventional length-at-age data. All investigated estimation techniques returned the known simulated growth parameters when the data is without error. When errors are introduced in the simulation, Bayesian implementations of Fabens' (BFa) and Francis’ (BFr) methods were found to be most reliable. For the observed mark-recapture data only BFa gave biologically plausible results for all 14 elasmobranch stocks. Overall, the results suggest that BFa is a reliable alternative to conventional length-at-age methods for estimating growth parameters, especially in data-limited situations which commonly occur with elasmobranchs. The only prior information needed is limited expert knowledge on maximum length in the population or stock in question. A user guide is provided to facilitate application of the method.

Developmental osteology of Ictalurus punctatus and Noturus gyrinus (Siluriformes: Ictaluridae) with a discussion of siluriform bone homologies

Abstract The skeleton of Siluriformes is characterized by several autapomorphies, including secondary absence, extreme modification, and purported fusion of several ossifications. Although well documented in adults, information on skeletal development in catfishes is relatively sparse and typically focused on particular regions of the skeleton (e.g., Weberian apparatus). To further our understanding of the siluriform skeleton, I document the development of the entire skeleton in two ictalurid species, Ictalurus punctatus (channel catfish) and Noturus gyrinus (tadpole madtom) from five days pre-hatch to adult. I reexamine the homologies of bones previously hypothesized to represent compound elements in catfishes as well as an additional element only known to occur in some ictalurids. Development of the skeleton is complete in I. punctatus at 22.4 mm SL and almost complete in N. gyrinus (except dorsal- and anal-fin distal radials) at 14.1 mm SL. No signs of ontogenetic fusion were observed in any of the purported compound elements. Previous hypotheses of the homology of these elements and of additional ossifications are reviewed in light of developmental information obtained herein. No dermal parietal component is present at any stage in the so-called parieto-supraoccipital. The bone is the supraoccipital which ossifies from two lateral centers of ossification which later fuse, rather than from a median center. The ‘posttemporo-supracleithrum’ originates from a single center of ossification and represents the supracleithrum. The posttemporal is present in ictalurids and many other catfishes as a canal-bearing bone between the supracleithrum and the pterotic, a bone sometimes identified as the extrascapular. The extrascapular is missing in catfishes. Ictalurids have an additional dermal bone above the posttemporal, which is either an independently ossifying fragment of the posttemporal or a neoformation restricted to some members of this family. The single chondral bone of the pectoral girdle originates from a single center of ossification that represents the coracoid. The scapula is missing in catfishes. Dorsal-fin distal radial 2 is absent in catfishes and the foramen of dorsal-fin spine 2 is formed from modifications to the base of the fin-ray itself. Unlike loricarioid catfishes, the urohyal of ictalurids originates solely as an ossification of the sternohyoideus tendons. The anteriormost infraorbital element ossifies from a single center of ossification around the infraorbital sensory canal and represents the lacrimal. The antorbital is missing in catfishes. Finally, skeletal development of I. punctatus is compared to that available for other otophysans, including the cypriniforms Danio rerio and Enteromius holotaenia and the characiform Salminus brasiliensis.

Acanthopagrus oconnorae, a new species of seabream (Sparidae) from the Red Sea.

A new species of sparid fish, Acanthopagrus oconnorae, is described based on 11 specimens collected in the shallow (0-1m depth) mangrove-adjacent sandflats of Thuwal, Saudi Arabia. The new species is distinguished from its congeners by the following combination of characters: second anal-fin spine 12.8%-16.6% of standard length (SL); 3½ scale rows between the fifth dorsal-fin spine and lateral line; suborbital width 5.7%-6.7% of SL; eyes positioned at the anterior edge of the head, often forming a weakly convex break in an otherwise gently curved head profile, when viewed laterally; caudal fin light yellow with black posterior margin (approximately half of fin); anal fin dusky grey, with posterior one-fifth of the fin light yellow; black streaks on inter-radial membranes of anal fin absent. The most similar species to A. oconnorae is Acanthopagrus vagus, which differs by the presence of a w-shaped anterior edge of the scaled predorsal area, a more acute snout and black streaks on the inter-radial membranes of the anal fin. Phylogenetic placement and species delimitation of A. oconnorae are discussed based on COI, CytB and 16S sequences. It is hypothesized that ecology and behaviour explain how this species avoided detection despite its likely occurrence in coastal areas of the Red Sea with historically high fishing pressure.

Hoplostethus roseus, a new roughy fish from the western Pacific based on morphology and DNA barcoding (family Trachichthyidae).

A new species of the roughy fish genus Hoplostethus is described from 11 types and a non-type specimen collected from Taiwanese waters. It can be distinguished from its congeners by a combination of characters: pectoral-fin rays 14-17 (modally 15-16); pyloric caeca 65-84; total gill rakers 19-20; predorsal scales 18-22; oral cavity, branchial chamber, top and underside of tongue, and peritoneum uniformly black; distal margin of membrane between dorsal-fin spines black; caudal fin without a black margin; caudal-fin base brownish. Comparisons of the new species with similar species are provided. DNA barcoding supports the monophyly of the new species, which appears to be closely related to Hoplostethus japonicus [average cytochrome c oxidase subunit I Kimura-2-parameter (COI K2P) distance of 4.1%].

A new species of deep-sea grunt, Rhonciscus pauco (Lutjaniformes: Haemulidae), from Puerto Rico.

A fourth species of the genus Rhonciscus (Lutjaniformes: Haemulidae) is described from various specimens collected by small-scale fishers from the insular upper slope of western Puerto Rico. The new species was molecularly recovered as sister to the Eastern Pacific R. branickii, to which it bears many morphological similarities. It is distinguished from other Rhonciscus species by the number of scale rows between the dorsal fin and the lateral line (7), larger and thus fewer scales along the lateral line (48–50), large eyes (9.4–10.4 times in SL), longer caudal peduncle (15.2–20% of SL), larger sized penultimate (14.7–19.1% in SL) and last (7.4–9.5% in SL) dorsal fin spines which translates to a less deeply notched dorsal fin, and its opalescent silver with golden specks live coloration. This grunt, only now recognized by ichthyologists, but well known by local fishers that target snappers and groupers between 200 and 500 m in depth, occurs in far deeper waters than any western Atlantic grunt.

Dario tigris and Dario melanogrammus, two new species of miniature chameleon fishes from northern Myanmar (Teleostei: Badidae).

Dario tigris, new species, is described from mountain streams south of Mogaung, in the Ayeyarwaddy River basin, Myanmar. It differs from congeneric species by its unique colour pattern, which consists of a series of eight straight vertical bars, the first two of which in males are ash-grey and the subsequent six are orange-red in life, combined with a series of small black spots arranged in three to four rows dorsolaterally on the head and nape. It differs further from its close relative Dario hysginon, with which it may occur syntopically, by fewer dorsal-fin spines (modally 14 vs modally 15), and fewer vertebrae (modally 12+12=24 vs modally 12+13= 25). Dario melanogrammus, new species, is another barred Dario from the Chindwin River basin. It differs from all other species of the genus by its zigzagging dark vertical bars; amongst Myanmar species, it can be further distinguished from D. hysginon and D. tigris by more vertebrae (modally 26 vs 25 in D. hysginon, and 24 in D. tigris).

A new Chinese perch (Perciformes, Sinipercidae) from the early Miocene of South Korea

ABSTRACT A new species of Chinese perch (Perciformes, Sinipercidae), †Coreoperca chosun, sp. nov., is described based on four specimens (mostly fragmentary and disarticulated) found in the freshwater Lower Miocene Geumgwangdong Formation in the vicinity of Pohang City, South Korea (N35°57′30.5, E129°26′57.3). Such characters of this fossil sinipercid as the serrated ventral margin of the preopercle, the third dorsal-fin spine being shorter than the fourth and fifth spines, the third to fifth neural spines inserted shallowly rather than deeply between the proximal dorsal-fin pterygiophores, the relatively strong supraneurals and relatively large scales indicate its attribution to the genus Coreoperca. However, its unique combination of characters clearly distinguishes †C. chosun, sp. nov. from both the extinct and extant members of the genus Coreoperca. This is the first fossil record of the family Sinipercidae in the Korean Peninsula, one of the earliest representatives of Coreoperca known to date, and the first described Neogene freshwater fish from South Korea.

Mystus irulu, a new species of bagrid catfish from the Western Ghats of Karnataka, India (Teleostei: Bagridae).

Mystus irulu, new species, is described from the Netravathi River system from the Western Ghats of Karnataka. It differs all South Asian congeners in having a uniformly black colour pattern, a long-based adipose fin reaching the base of the last dorsal-fin ray anteriorly, dorsal fin with convex dorsoposterior margin, and the following combination of characters: body depth at anus 19.922.3 % SL, dorsal-fin spine length 17.518.7 % SL, adipose-fin base 34.238.4 % SL, caudal peduncle depth 10.611.9 % SL and eye diameter 27.237.1 % HL.

Cirrhilabrusfinifenmaa (Teleostei, Labridae), a new species of fairy wrasse from the Maldives, with comments on the taxonomic identity of C.rubrisquamis and C.wakanda.

Cirrhilabrusrubrisquamis is redescribed on the basis of the juvenile holotype and compared to known species of Cirrhilabrus. Examination of material from the Maldives identified as C.rubrisquamis reveal differences from the holotype collected from the Chagos Archipelago. Consequently, the Maldivian specimens are herein described as Cirrhilabrusfinifenmaasp. nov., on the basis of the holotype and twelve paratypes. The new species differs from all congeners in having: males with anterior third to half of body bright magenta, peach to orange-pink posteriorly; lateral line with 22–26 pored scales (16–18 in the dorso-anterior series, 6–8 in the posterior peduncular series); tenth to eleventh dorsal-fin spine longest (14.0–15.5% SL); scales on the opercle, chest, isthmus, and anterior third of the body with a dark purple-red central region (purple in alcohol), the markings joining appearing crosshatched; dorsal, caudal, anal, and pelvic-fin rays purple in alcohol. Meristic details and coloration patterns of C.rubrisquamis are very similar to C.wakanda from Tanzania, Africa, although synonymy of both species cannot be determined without additional material from Chagos. This potential synonymy is briefly discussed; however, until such material becomes available, the taxonomic statuses of C.wakanda and C.rubrisquamis are here provisionally regarded as valid.

Redescription of Parapercis moki Ho and Johnson, 2013 (family Pinguipedidae), with its first fresh coloration information.

Two specimens of Parapercis moki Ho Johnson were collected recently and detailed descriptions of their morphology and fresh coloration are provided. Its diagnosis is now revised as: band across head, six transverse bands on body and blade-like bar below eye; numerous small pores connected by canals forming about 910 vertical rows on cheek, opercle, and subopercle; scales on nape extending anteriorly to level of posterior margin of eyes; large spine on posteroventral corner of subopercle; very narrow interorbital space (1.72.0% SL); 4 dorsal-fin spines, each spine progressively longer, last spine entirely connected by membrane to first dorsal-fin ray; four pairs of canine teeth anteriorly in lower jaw; and palatine teeth present, in two rows, and vomerine teeth stout, in two rows.