Spatial distribution and life‐history aspects of blackspot seabream Pagellus bogaraveo (Osteichthyes: Sparidae)

Spatial distribution and life history aspects of Pagellus bogaraveo in the eastern Ionian Sea were investigated using the data from 13 different studies carried out in the area from 1983 to 2010. The spatial patterns of the abundance, biomass and mean size showed that the species inhabits the shallow waters of the shelf (<170 m depth) as juveniles up to a certain size (<180 mm total length, L_T), moving to deeper waters of the slope (mainly 400–500 m depth) as adults. The spatial pattern of abundance indicated a continuous distribution of the species in deep waters, with hot‐spot areas of high values, whereas in shallow waters distribution was more discontinuous, with higher concentrations of juveniles in estuaries and brackish waters. The study of biological aspects of the species revealed (1) a difference in the increase in mass between males and females, (2) protandrous hermaphroditism, accompanied by the presence of primary females and males that do not change sex, (3) a sex ratio in favour of females >250 mm L_T, (4) the presence of hermaphrodites between 200 and 370 mm, (5) a long reproduction period from June to March, (6) a size at first maturity around 300 mm and (7) a diet composition of adults based mainly on fishes, and also on opportunistic behaviour in the food scarce environment of deep waters. The results suggest that the species' distribution and feeding strategies are the most appropriate for the oligotrophic eastern Ionian waters and that these conditions result in smaller sizes of the species in the east Mediterranean Sea compared to the west basin and the east Atlantic Ocean, with implications for the growth and reproductive biology of the species.     

Catch composition and reproductive biology of Sphyrna lewini (Griffith & Smith) (Carcharhiniformes, Sphyrnidae) in Indonesian waters

Data on the length compositions and reproductive biology have been collected for Sphyrna lewini in Indonesian waters, in which this species makes an important contribution to the biomass of its artisanal and small‐scale fisheries. These data were obtained by recording relevant body measurements and counts for this species while visiting Indonesian fish landing sites. The fish, which had been caught by gillnetting and longlining, covered a wide length range and included substantial numbers of immature, maturing and mature individuals. The vast majority of S. lewini <1100 mm total length (L_T) had been caught by gillnetting, whereas most of those above this length had been obtained through longlining. The number of embryos in pregnant females, which ranged from 14 to 41, with a mean of 25, was positively correlated with the L_T of those females. Birth occurred at c. 400 mm L_T and predominantly in October and November. The number of females was similar to that of males among smaller fish, but far greater than that of males among larger fish. This presumably reflects a faster growth and greater longevity of females, selectivity of longlining for females and a tendency for males to move outside the area fished. For males, the relationships between clasper length and the extent of its calcification, and also with sexual maturation and L_T have been determined. Females attained maturity (L_T50) at a far larger size (2285 mm) than males (1756 mm). The L_T of virtually all females and all males taken by gillnetting were less than their respective L_T50 at maturity, and c. 67 and 51% of the longline catches of females and males, respectively, were likewise immature. This feature, together with the substantial catches of S. lewini and the life cycle traits of elasmobranchs, suggest that this species is likely to be prone to overfishing in Indonesian waters. Furthermore, the removal of large numbers of this apex predator will presumably be affecting the trophic structure in the waters in which it is fished.     

Acoustic ontogeny of a teleost

The influence of growth on the intensity and variability of acoustic echoes from individuals and groups of a teleosts was quantified using Donaldson trout (rainbow–steelhead hybrid) Oncorhynchus mykiss. Fish growth was linear in total length (L_T) and quadratic in mass. Dorsal swimbladder area increased exponentially with L_T. Allometric growth ratio (i.e. k) values of swimbladder length linearly increased with L_T. Average swimbladder volumes occupied 3–6% of fish body volume and increased exponentially with L_T. The aspect angle that resulted in the maximum average acoustic intensity from the group shifted from 80 to 86° through the experimental period. Mean echo intensities increased at both 38 and 120 kHz as mean L_T increased. Predicted echo intensities at 38 kHz exceeded that at 120 kHz at L_T <150 mm but were less than that predicted at 120 kHz at L_T >280 mm. Generalized additive mixed models using L_T, swimbladder angles and lateral elongation ratios of fish bodies were better predictors of echo intensities than L_T alone.     

Reproductive biology of the fat snook Centropomus parallelus Poey, 1860 (Teleostei,Centropomidae) and implications for its management in the southern Atlantic Ocean

The reproductive biology of Centropomus parallelus was described from 589 individuals captured in estuarine and coastal waters in Southern Brazil. Length-frequency distribution showed the dominance of males in smaller length-classes (132–290 mm L_T), whereas females were dominant in larger length-classes (>290 mm L_T). Total length at maturity (L₅₀) was 180 mm L_T and corresponded to 29% of the maximum length recorded. Histological sections revealed one hermaphrodite (205 mm L_T) and few immature females. Life history traits provided herein can contribute to sustainable fisheries management practices.     

Gonadal development in a giant threatened reef fish,the humphead wrasse Cheilinus undulatus,and its relationship to international trade

An opportunity arose to obtain humphead wrasse Cheilinus undulatus specimens between 2006 and 2009 from Indonesia, the major source and exporting country of this species, making study on its early gonad development possible for the first time. Protogynous hermaphroditism, previously proposed for this species, was confirmed in this study. Based on histological examination of 178 specimens, mainly <500 mm total length (L_T) and ranging from 208 to 1290 mm L_T (119·1 g to 43·0 kg whole body mass), the minimum body sizes for female and male sexual maturation were determined to be 650 and 845 mm L_T, respectively. Primary male development through juvenile sexual differentiation was not detected. A unique blind pouch, with a possible sperm storage function and associated with the testis, was reported for the first time in the Labridae. In Hong Kong retail markets, the global trading centre for this valuable species, live C. undulatus on sale for food were dominated by body sizes <500 mm L_T between 1995 and 2009, reflecting an international trade largely focused on juveniles. In consideration of these findings, and given the threatened status of this species, management for C. undulatus capture and trade nationally and internationally are discussed with recommendations for ensuring sufficient spawning biomass in exploited populations and for sustainable trade.     

Age structure and growth of Semotilus atromaculatus(Mitchill) in PCB‐contaminated streams

Creek chub Semotilus atromaculatus from two PCB contaminated streams (Clear Creek and Richland Creek) at three locations and a reference stream (Little Indian Creek), Indiana, U.S.A., were examined to determine if age class structure and growth variables were correlated with in‐situ PCB exposure. Approximately five to 15 fish were captured weekly during the spring spawning season and monthly thereafter for a 12 month period. Fish collected ranged from 25 to 267 mm total length (L_T). Throughout the course of this study, no spawning activity was observed at either location in Clear Creek, although some very small young‐of‐the‐year (YOY) creek chub fry were observed at the downstream location by late summer. Creek chub nests were observed in both Richland Creek and Little Indian Creek but YOY were common only in Little Indian Creek. Exposure to PCBs was shown to both enhance and decrease growth in varied laboratory tests; subtle but significant gender‐specific differences in the growth of creek chub populations between the sites were observed. Creek chub up to 24 months in age from Clear Creek and Richland Creek were significantly larger (both L_T and mass for males and L_T for females) than reference site creek chub. This trend was reversed for creek chub aged ≥24 months as the reference site fish were consistently larger with reference males weighing significantly more. Older age classes of creek chub were missing in areas of higher PCB contamination. Female population growth rates and individual instantaneous growth rates were consistently higher at the reference site in comparison to the PCB‐contaminated sites. Calculation of ‘functional b’(as a condition factor) did indicate that growth enhancement in young males did occur at the most contaminated site and reductions in growth (mass relative to L_T) occurred in females from all contaminated sites. Furthermore, long‐term survivorship for females was reduced in the PCB‐contaminated streams. All of these subtle alterations in growth would not have been observed if males and females had not been analysed separately.     

Introduced bullheads Cottus gobio and infection with plerocercoids of Schistocephalus cotti in the Utsjoki, an Arctic river in Finland

Bullheads Cottus gobio, first found in the River Utsjoki, an Arctic river in Finland, in 1979, were sampled at six sites in August 1991 (two of these sites were also sampled previously in June and July 1991). Mean total length (L_T) of C. gobio was 45 mm (n= 1080 fish). Overall, there were slightly more females than males, with males larger than females (mean L_T males 52·1 and females 47·6 mm). Prevalence of infection with plerocercoids of Schistocephalus cotti varied from 20·0 to 43·0% over the six sites in August. Juvenile C. gobio had a prevalence of infection of 3·5% whereas in mature fish prevalence was consistently higher in females than in males (38·8 v. 20·1%). There was one plerocercoid per infected juvenile C. gobio. In mature fish the mean number varied between 1·3 and 1·8: 49% had one worm per fish, 38% two or three worms and 13% had four to eight plerocercoids. In juvenile C. gobio, S. cotti were randomly distributed (overdispersion index 1·10), whereas occurrence was slightly aggregated in the L_T groups 40–59 and ≥60 mm (overdispersion indices both 1·90). Mean mass of infected fish was higher in all L_T groups compared to uninfected C. gobio. After removal of plerocercoids, mean mass of fish tissue remaining was lower compared with uninfected fish for the two L_T groups 40–59 and ≥ 60 mm, but higher in C. gobio <40 mm L_T. Prevalence and mean intensity of infection over the 3 months did not differ either for the two sites individually or the pooled data. Mean mass of both uninfected and infected fish increased over this period, and were both highest in August as was the mean worm burden. There was, however, no difference in Fulton’s condition factor at any time. Mean mass of plerocercoids in C. gobio of ≥40 mm L_T increased significantly comparing June and July with August. Comparison of backcalculated L_T of infected and non‐infected bullheads of different age‐groups did not show any significant differences in growth at any age. In each parasite infrapopulation as the number of worms increased so their mean mass decreased significantly but at the same time the total mass of worms in the fish host remained more or less constant in relation to length. Aggregation of parasites in the fish population was low, as the majority were infected by one S. cotti plerocercoid. Gonad development was suppressed in infected C. gobio.     

Life history of the river goby Glossogobius callidus (Teleostei: Gobiidae)

The river goby Glossogobius callidus is native to freshwater and estuarine habitats in South Africa. Individuals [21.1–144.4 mm total length (L_T)] were sampled from impoundments in the Sundays River Valley, Eastern Cape, from February 2014 to March 2015. The largest female was 137.2 mm L_T, and the largest male was 144.4 mm L_T. Length-at-50% maturity was 75.2 ± 2.1 mm L_T for males and 76.2 ± 2.0 mm L_T for females. Absolute fecundity was 1028.2 ± 131.7 oocytes per fish, and relative fecundity was 50.1 ± 18.1 oocytes per gram. The spawning season extended from October to December. Fish were aged using sectioned sagittal otoliths. The growth zone periodicity was validated using edge analysis. Longevity was more than 7 years for females and more than 6 years for males. Length-at-age was similar for the two sexes and was best described using the von Bertalanffy growth model as L_t = 74.7(1 − e^{–1.0(t + 0.1)}) mm L_T for the entire population. Using the population age structure, the mortality rate was estimated at 1.3 per year.     

Observations of stranded and swimming whale sharks Rhincodon typus in Khor Al-Zubair,NW Arabian Gulf and Shatt Al-Arab Estuary,Iraq

This study is the first record of a whale shark Rhincodon typus in Iraqi waters and the second record from the Arabian (Persian) Gulf portion of the north-west Indian Ocean. The stranding and sighting events were documented by photos of three individuals: the stranded specimen was 6.5 m total length (L_T) and the free-swimming individuals were c. 1–2 and 2–3 m L_T respectively_. An appeal is made for Iraqi policy makers to participate in regional and international organizations for the conservation of this endangered species.     

Skeletal ontogeny of the vertebral column and of the fins in shi drum Umbrina cirrosa (Teleostei: Perciformes: Sciaenidae), a new candidate species for aquaculture

The osteological development of the vertebral column and fins in shi drum Umbrina cirrosa was studied in order to improve knowledge for its introduction in Mediterranean aquaculture. The osteological development was studied in 171 individuals, of total length (L_T) from 2·7 to 30·2 mm that were reared under the mesocosm technique. Vertebral ontogeny starts at 3·4 and 4·0 mm L_T, with the formation of the first cartilaginous neural and haemal arches, and spines, respectively, and is completed with the full attainment of epicentrals (12·5 mm L_T). The formation of vertebral centra occurs between 4·1 and 7·4 mm L_T. Pectoral supports are the first fin elements to develop (3·0 mm L_T), followed by those of the caudal fin (3·8 mm L_T), pelvic fin (3·9 mm L_T) and finally by those of the dorsal and anal fins (4·5 mm L_T). The caudal fin is the first to develop fin rays and attain the full count of principal fin rays (4·5–6·8 mm L_T), but the last to be fully completed with the formation of procurrent fin rays (6·9–17·5 mm L_T). The next fins starting to present rays are the dorsal (5·3 mm L_T) and the pectoral fins (5·6 mm L_T), while the anal and pelvic fins are the last (5·7 mm L_T). Following the caudal principal fin rays (6·8 mm L_T), the dorsal, anal (6·9 mm L_T), pelvic (7·4 mm L_T) and pectoral fins (9·8 mm L_T) are the next with fully completed ray counts. Aggregation of qualitative changes, such as the appearance of cartilages, the beginning and the complement of the ossification process and the full complement of elements in U. cirrosa were measured as cumulative frequency counts. These measurements reveal three ontogenetic intervals: one very developmentally active period during early life stages (from 3 to 5·9 mm L_T), a second slower developmental period (from 6·0 to 8·9 mm L_T) and finally a period of ontogeny more focused on structure refinement up to metamorphosis and settlement (>9·0 mm L_T).     

Catch composition,reproductive biology and diet of the bramble shark Echinorhinus brucus (Squaliformes: Echinorhinidae) from the south‐eastern Arabian Sea

Fishery and biological data are presented for the poorly known bramble shark Echinorhinus brucus (Squaliformes: Echinorhinidae), from the deep waters of the south‐eastern Arabian Sea. A total of 5318 individuals from by‐catch landings of deep‐water bottom set longlines, gillnets and shrimp trawl fisheries operating at depths of 200–1200 m were recorded between January 2008 and December 2011 at the Kochi Fisheries Harbour (Kerala). A total of 431 individuals, from 46 to 318 cm total length (L_T) and 0·8 to 132 kg total mass (M_T), were examined to determine biological data for this species. The L_T at which 50% were mature (L_T50) for females and males was estimated at 189 and 187 cm L_T. Litter size ranged from 10 to 36 and size at birth was between 42 and 46 cm L_T. Dietary analysis of stomach contents revealed E. brucus feeds on a variety of prey including crustaceans (69% index of relative importance, I_RI), teleosts (25·8% I_RI), cephalopods (1·7% I_RI) and elasmobranchs (0·7% I_RI). This study provides the first detailed biological data for this species and also highlights the extent of the by‐catch fishery for this species in Indian waters.     

Biology of the kingsoldier bream (Argyrops spinifer, Forsskål 1775; Sparidae), from the Arabian Sea, Oman

It is recognized by the FAO that management of fish resources in the western Indian Ocean is complicated by the lack of data on the basic biology and landing statistics for exploited fish species. In this paper data are presented on the population biology of kingsoldier bream, Argyrops spinifer (Forsskål 1775), in the Arabian Sea with a view to contributing towards the development of management plans for its sustainable exploitation. Samples were obtained from the Omani artisanal hand‐line fishery catch, January 2001–December 2002. Total length (L_T) of fish sampled ranged from 20 to 68 cm (males) and 25 to 70 cm (females). The male : female ratio was similar up to 55 cm L_T but the larger size‐classes were composed predominately of male fish. L_T/carcass weight (W_C) relations for male and female fish were similar and the combined data produced an equation W_C = 0.00005 × L_T^2.67. Marginal increment analysis indicated an annual cycle of opaque and translucent ring formation in otoliths that was related to the change in surface water temperature during the annual monsoon period. The opaque zone was completed in May and the translucent zone began to form in June. Female and male fish age ranged between 2 and 25 years. Both males and females exhibited similar asymptotic growth patterns; the combined von Bertalanffy growth function was L_t = 64.6(1 ? e^{[?0.142(t + 0.489)]}). Gonadosomatic indices and gonad condition of male and female fish indicated that the spawning season occurred between September and January. Size (L₅₀) and age at first maturity (A₅₀) were estimated to be 36.5 cm L_T and 5.0 years for males and 37.2 cm L_T and 5.6 years females, respectively. The results of this study provide fundamental information on the biology and population dynamics of A. spinifer in the Arabian Sea that can be used in management models for the continued sustainable exploitation of this species in the Omani demersal coastal fisheries.     

Diel shifts in the structure and function of nearshore estuarine fish communities

Day–night shifts in the nearshore fish fauna of a temperate microtidal estuary were assessed using a holistic suite of structural and functional community attributes. Mean fish species richness and diversity (taxonomic distinctness) were higher at night across all regions of the estuary and seasons, concurring with the findings of numerous comparable studies reviewed worldwide, while the diel period in which mean abundance was higher varied among seasons. Likewise, species and functional guild compositions (the latter based on feeding modes and habitat use) both differed significantly between day and night, with the extent of the diel shift again varying seasonally. Daytime fish communities were characterized by higher abundances of Atherinidae, Sillaginidae and Mugilidae, while Gobiidae were far more abundant at night. Marked shifts in size composition were also evident, with smaller fishes (<100 mm total length, L_T) being more prevalent during the day and larger fishes (≥200 mm L_T) proportionally more abundant at night. The above diel shifts were feasibly related to a range of predator–prey interactions and feeding‐related movements, namely a nocturnal decrease in top‐order avian piscivory coupled with an increase in invertebrate prey availability, resulting in changes in the presence and catchability of certain fish species in shallow estuarine waters.     

Manual fish length measurement accuracy for adult river fish using an acoustic camera (DIDSON)

Total lengths (L_T) of 50 free-swimming fish in a tank, silver carp Hypophthalmichthys molitrix and rainbow trout Oncorhynchus mykiss, were measured using a DIDSON (Dual-frequency IDentification SONar) camera. Using Sound Metrics software, multiple measurements of each fish (L_T, side aspect angle and distance from the camera) at different times were analysed by two experienced operators while a subset of data was analysed by two inexperienced operators. The main result showed high variability in intra-fish L_T measurements. The number of measurements required to minimise errors and to obtain robust fish measurements (true L_T ± 3 cm) was estimated by a bootstrap method. Three to five measurements per fish were recommended for fish surveys in rivers. In this experimental study, aiming to reproduce river conditions, no evidence of fish position (side aspect angle and distance from the camera) effect was detected, but an operator effect (partially explained by training) was observed. General linear mixed models also showed that lengths of the smallest fish (L_T < 57 cm) were overestimated and lengths of the largest fish (L_T > 57 cm) were underestimated in comparison with their true lengths. In conclusion, we highlight that this technology, like any monitoring methods, returns imperfect observations. We advise DIDSON users to ensure that measurements are carried out correctly in order to draw accurate conclusion from this new technology.     

Migration and reproductive biology of Mugil liza (Teleostei: Mugilidae) in south Brazil

The mullet Mugil liza occurs along the Atlantic coast of South America from Venezuela to Argentina, but 95% of the commercial catch is collected from south Brazil between São Paulo and Argentina. Mugil liza is a single spawner with oocyte development occurring synchronously in two groups. Spawning happens in marine areas and occurs after migration. The reproductive migration occurs from Argentina (38° S) to the southern Brazilian states (24–26° S) from April to July, with peak spawning in June between northern Santa Catarina and Paraná. The presence of hyaline oocytes was associated with high salinity and sea surface temperatures of 19–21° C, and followed the seasonal northward displacement of these oceanographic conditions. The average size at first maturity (L_m) for both sexes was 408·3 mm total length, L_T. Males (L_m = 400·1) matured earlier than females (L_m = 421·9 mm). Fecundity ranged from 818 992 to 2 869 767 oocytes (mean = 1 624 551) in fish that were between 426 and 660 mm L_T.     

Reproductive biology of the tarpon snook Centropomus pectinatus (Perciformes,Centropomidae) in estuarine waters in the south‐western Atlantic

The reproductive biology of Centropomus pectinatus is described from an artisanal fish landings collaborative monitoring programme between May 2012 and April 2013 in estuarine waters in north‐eastern Brazil. The total length (L_T) at which 50% are mature was 24 cm, corresponding to 37·7% of the maximum recorded L_T. Gonado‐somatic indices were variable, but highest values were in June and August 2012. Length‐frequency distributions showed male dominance in smaller length classes (15–30 cm) and females in larger length classes (>30 cm).     

Biological observations on the broadfin shark Lamiopsis temminckii (Carcharhiniformes: Carcharhinidae)

Biological information was collected from 214 individuals of the broadfin shark Lamiopsis temminckii measuring 418 to 1782 mm total length, L_T. Size at maturity (L₅₀) for females and males was estimated at 1430 and 1368 mm L_T, respectively, while mature and gravid females were observed from 1350 mm L_T with litter sizes 2–8 and size at birth 418–650 mm L_T. Analysis of stomach contents revealed a variety of prey, primarily crustaceans (54·0%), teleosts (42·7%) and cephalopods.     

Population biology of an endangered species: the common guitarfish Rhinobatos rhinobatos in Lebanese marine waters of the eastern Mediterranean Sea

This study focuses on the population biology of the common guitarfish Rhinobatos rhinobatos, a cartilaginous fish listed as Endangered in the International Union for the Conservation of Nature (IUCN) Red List. Between December 2012 and January 2014, 67 individuals were collected by bottom longlining in coastal Lebanese marine waters at different ports at depths ranging from 10 to 110 m. The total length (L_T) of the specimens ranged from 50 to 143 cm, and the mean ± s.d . was 76·2 ± 19·7 cm. The most common L_T classes were between 60 and 70 cm. The total mass of the specimens ranged from 410 to 10 000 g, and the mean ± s.d . was 1841 ± 1987 g. A total of 34 males and 33 females were collected, and the sex ratio was not significantly different from 1:1. The mass and L_T relationship showed positive allometric growth (b = 3·096 and r² = 0·99), and the mean ± s.d . L_T at which 50% of the individuals were sexually mature was 84·73 ± 5·81 cm for females and 78·57 ± 4·88 cm for males. The gonado‐somatic and hepato‐somatic indices were determined along with a condition factor, and parturition appeared to occur in winter. The primary prey items found in the fish stomachs during the autumn and winter seasons were Penaeidae. The results of this study will help to parameterize models of the population dynamics for this exploited fish stock to ensure the long‐term sustainability of its fishery.     

Head‐shape polymorphism in Japanese eels Anguilla japonica in relation to differences of somatic growth in freshwater and brackish habitats

The age, total length (L_T), head shape and skull shape were investigated for 379 Japanese eels Anguilla japonica sampled in freshwater and brackish areas of the Kojima Bay–Asahi River system, Okayama, Japan, to learn about the differentiation process of head‐shape polymorphism. The relative mouth width (ratio of mouth width to L_T) of A. japonica > 400 mm L_T collected in fresh water was significantly greater than that of fish collected in brackish water. Growth rates of mouth width and the distance from the snout to the midpoint of the eyes (the ratio of width and distance to age, respectively) were not significantly different between freshwater and brackish‐water samples, whereas the somatic growth rate (the ratio of L_T to age) of freshwater samples was significantly lower than that of brackish‐water eel samples. These results suggest that the factors affecting head and somatic growth of A. japonica are not identical. According to these results and feeding patterns in each habitat reported by another study, it is suggested that somatic growth appears to play a significant role in the differentiation process of the head‐shape polymorphism in A. japonica, with the slow‐growing fish in fresh water becoming broad‐headed and the fast‐growing fish in brackish water becoming narrow‐headed.     

Reproductive biology and feeding habits of the prickly dogfish Oxynotus bruniensis

The reproductive biology and diet of prickly dogfish Oxynotus bruniensis, a deep‐sea elasmobranch, endemic to the outer continental and insular shelves of southern Australia and New Zealand, and caught as by‐catch in demersal fisheries, are described from specimens caught in New Zealand waters. A total of 53 specimens were obtained from research surveys and commercial fisheries, including juveniles and adults ranging in size from 33·5 to 75·6 cm total length (L_T). Estimated size‐at‐maturity was 54·7 cm L_T in males and 64·0 cm L_T in females. Three gravid females (65·0, 67·5 and 71·2 cm L_T) were observed, all with eight embryos. Size‐at‐birth was estimated to be 25–27 cm L_T. Vitellogenesis was not concurrent with embryo development. Analysis of diet from stomach contents, including DNA identification of prey using the mitochondrial genes cox1 and nadh2, revealed that O. bruniensis preys exclusively on the egg capsules of holocephalans, potentially making it the only known elasmobranch with a diet reliant solely upon other chondrichthyans. Based on spatial overlap with deep‐sea fisheries, a highly specialized diet, and reproductive characteristics representative of a low productivity fish, the commercial fisheries by‐catch of O. bruniensis may put this species at relatively high risk of overfishing.