Seven coastal fish species are newly reported for the remote north Atlantic archipelago of the Azores: Mediterranean sand eel Gymnammodytes cicerelus, bar jack Caranx ruber, two‐banded seabream ...Diplodus vulgaris, bastard grunt Pomadasys incisus, unicorn leatherjacket filefish Aluterus scriptus and longspined porcupinefish Diodon holacanthus. The occurrence is also confirmed
for 19 species that had been hitherto cited occasionally for the region, totalling a list of two elasmobranchs and 23 teleosts. Diplodus vulgaris, which appears to have recently colonized the islands, as well as roughtail stingray Dasyatis centroura and golden grey mullet Liza aurata, re‐cited based on new records, are frequent or common coastal species in the Azores. The remaining 22 species, exceptional or rare in the region, are of tropical or subtropical affinity and find their northernmost distribution limit within the central and north‐east Atlantic Ocean precisely in the Azores. This biogeographical pattern contrasts with that of the Azorean coastal fish community and suggests a tropicalization process in the region in line with previous findings of similar patterns across the north‐east Atlantic Ocean and the Mediterranean Sea. These novel data from the most isolated archipelago of the North Atlantic Ocean, located in a biogeographic boundary area where colonization opportunities are reduced, reinforce the need for long‐term monitoring programmes of coastal fish communities and, in particular, of indicator species groups to improve understanding of the effects of climate change on marine communities.
The effects of sex, age, and environment on the shape of the bastard grunt (
Pomadasys incisus
) otoliths from the north-western Mediterranean were investigated. Specimens of this species were ...collected from two separate sampling areas in the north-western Mediterranean with different thermal regimes. Sex, growth rates, and age of
P. incisus
were determined by using gonad histology techniques, biometric analyses, and otolith microstructure analyses, respectively. The shape was described using normalized Elliptic Fourier descriptors (EFDs), and studied by means of multivariate statistics as predictive variables with age-specific discriminant analyses. There were no consistent differences found between sexes, but otolith shapes varied significantly between environments within different age classes. Total classification success varied between 87.3% and 89.2% between environments for the different age classes and provided a phenotypic basis for
P. incisus
population separation within an environmental gradient in determining its otolith shape. In addition, significant differences were observed between sampling areas in von Bertalanffy’s growth parameters, as well as in the fish length-weight (LWR) and fish length-otolith radius (TL-Ro) relationships. Data was discussed considering that the physical habitat variability could underlie a marked change in otolith shape during the animals’ growth. In this matter, we discussed the relative importance of both ontogenetic and environmental conditions (such as water temperature) on otolith shape.
For the first time three specimens belonging to the species Pomadasys incisus (Bowdich, 1825), the bastard grunt, were caught in the French Ligurian Sea. This subtropical species, which naturally ...entered the Mediterranean Sea through the Straits of Gibraltar in the first half of the nineteenth century, and is currently colonizing the whole Mediterranean coast except the Adriatic Sea, was until now unknown for this region. We reviewed its distribution after a compilation of the available literature, and tried to explain the spreading and the establishment of the bastard grunt as a Mediterranean species in light of the prevailing Mediterranean currents and the possible climate changes.
The reproduction and feeding habits of the Bastard grunt, Pomadasys incisus (Bowdich, 1825), in the Gulf of Tunis were investigated monthly from January to December 2003. An examination of the gonads ...of 463 specimens showed that the Bastard grunt is a gonochoric species and the sexratio wasn't significantly different from 1:1. The monthly variations of the gonadosomatic index and the percentage of the different gonadal development stages revealed that P. incisus spawning period occurred from August to October. This species uses its energetic reserves contained in the liver and the muscles to assure gonadal maturation. The size at first maturity (L sub(50)) was estimated at 15.33 cm for both sexes pooled. The stomachs examined showed a high vacuity index throughout the year (56.8%) and presented a significant difference between seasons. The stomach contents analysis revealed that P. incisus' diet was especially constituted of crustacean species as well as benthic and planktonic organisms that belong to 19 taxa. The percentage frequency of occurrence (F) computed for Crangon crangon, Hyperoche sp. and Geryon longipes (the most abundant prey in the diet) showed significant differences among seasons ( chi super(2) sub(obs) = 31.228, 29.471 and 11.302 respectively, were superior to chi super(2) sub(0.05)).Original Abstract: Istrazivane su reprodukcija i prehrambene navike morskog hroktaca, Pomadasys incisus (Bowdich, 1825), u tuniskom zaljevu od sijecnja do prosinca 2003. Istrazivanje gonada na 463 uzorka je pokazalo da je morski hroktac gonohoricna vrsta i da odnos medju spolovima nije znacajno odstupao od razmjera 1:1. Mjesecna kolebanja gonadosomatskog indeksa i postotka razlicitih stadija razvoja gonada otkrivaju da se P. incisus mrijesti od kolovoza do listopada. Ova vrsta koristi energetske pricuve iz jetre i misica kako bi osigurala sazrijevanje gonada. Izracunata duzina pri stadiju 50% zrelosti populacije (L sub(50)) iznosila je 15.33 cm za oba spola ukupno. Analizirani sadrzaj zeluca je pokazao vrlo visoki indeks ispraznjavanja tijekom godine (56.8%) sa znacajnom razlikom izmedju sezona (godisnjih doba). Ustanovljeno je takodjer da se prehrana P. incisus sastoji od rakova, bentickih i planktonskih organizama iz 19 taksonomskih skupina. Postotak ucestalosti pojavljivanja pronadjen za Crangon crangon, Hyperoche sp. i Geryon longipes (najzastupljenije u prehrani) ukazuje na znacajne razlike medju sezonama ( chi super(2) sub(obs) = 31.228, 29.471 odnosno 11.302, a bile su vece od chi super(2) sub(0.05)).
The bastard grunt (Pomadasys incisus) is one of the most abundant coastal demersal fishes inhabiting the Canary Islands. Age and growth were studied from samples collected between October 2000 and ...September 2001. Growth analysis revealed that this species is a fast growing and moderately short-lived species (ages up to seven years recorded). Length-at-age was described by the von Bertalanffy growth model (L∞ =309.58 mm; k=0.220/year; t0=-1.865 year), the Schnute growth model (y1=126.66 mm; y2=293.50 mm; a=-0.426; b= 5.963), and the seasonalized von Bertalanffy growth model (L∞ =309.93 mm; k=0.218/ year; t0= -1.896 year; C=0.555; ts=0.652). Individuals grow quickly in their first year, attaining approximately 60% of their maximum length; after the first year, their growth rate drops rapidly as energy is probably diverted to reproduction. The parameters of the von Bertalanffy weight growth curve were W∞ =788.22 mm; k=0.1567/year; t0= - 1.984 year. Fish total length and otolith radius were closely correlated, r2=0.912. A power relationship was estimated between the total length and the otolith radius (a=49.93; v=0.851). A year's growth was represented by an opaque and hyaline (translucent) zone― an annulus. Backcalculated lengths were similar to those predicted by the growth models. Growth parameters estimated from the backcalculated sizes at age were L∞ =315.23 mm; k=0.217/year; and t0= -1.73 year.
Pomadasys incisus is one of the most abundant coastal demersal species around the Canary Islands. It is a gonochoric species with similar biological characteristic in males and females. The adult sex ...ratio is not significantly different from 1:1, and the mean size of males and females is similar. It reaches first maturity at the end of the second year of life (183 mm). Spawning takes place throughout the year. Growth analysis reveals that the species is fast-growing and relatively short-lived (7 years). Length at age is well described by the von Bertalanffy growth model. Individuals grow quickly in their immature first year, attaining approximately 45% of their maximum length. After one year, the annual growth rate drops rapidly. The direct effects of fishing result in changes in abundance, with an 80% reduction from the unexploited equilibrium level. Recruitment into the commercial fisheries occurs before size at sexual maturity, resulting in all spawners being accessible using the current fishing pattern. The length at first capture (168 mm) is less than the length at maturity; 45% of the total catch are smaller than this, indicating a danger of recruitment-overfishing.Original Abstract: Parametros biologicos del Pomadasys incisus (Osteichthyes: Haemulidae) en el archipielago canario. - Pomadasys incisus es una de las especies demersales costeras mas abundantes en las aguas de las Islas Canarias. Es una especie gonocorica con caracteristicas que presenta caracteristicas similares para los machos y hembras. La proporcion de sexos no difiere de la relacion 1:1. Las tallas medias son similares para los machos y las hembras. Los individuos de esta especie alcanzan la madurez sexual al final del segundo ano de vida (183 mm). La puesta tiene lugar durante todo el ano. El analisis de su crecimiento muestra que la especie es de crecimiento rapido y de longevidad reducida (7 anos). La relacion entre la talla y la edad es descrita de forma adecuada por el modelo de von Bertalanffy. Los individuos inmaduros crecen de forma rapida durante sus primeros anos, alcanzando, aproximadamente, el 45 % de su talla maxima. Despues del primer ano de vida, la tasa de crecimiento se reduce considerablemente. El efecto directo causado por la pesca es una reduccion del 80 % de su biomasa con respecto al nivel de equilibrio previo a la explotacion. El reclutamiento ocurre antes de alcanzar la talla de madurez sexual y como consecuencia de ello todo el stock reproductor esta sometido a presion pesquera segun el patron de explotacion actual. La talla de primera captura (168 mm) es menor que la talla de madurez sexual, con un 45 % del total de individuos capturados por debajo de dicha talla de madurez, lo que apunta hacia una sobrepesca en reclutamiento. Palabras clave: Pomadasys incisus, crecimiento, reproduccion, mortalidad, impacto, descartes, Islas Canarias.
To optimize a visual evaluation technique of the fish assemblages, and describe environmental factors that structure the fish community, and determine the influence of the protection categories ...defined on the abundance and size of species of interest to fisheries, were carried out 88 visual assessments during the winter 1999-2000 and summer 2000 in the area of the Gando-Arinaga Marine Reserve (Gran Canaria, Canary Islands). 36 fish species were observed. Abudefduf luridus, Thalassoma pavo, Chromis limbatus, Sparisoma cretense and Diplodus vulgaris, were the most frequent species. Pomadasys incisus, Boop boops, A. luridus, C. limbatus, and T. pavo, the most abundant species. The mean number of species/census, the mean number of individuals, diversity and evenness, were also determined. Differences in size, abundance were detected for Mullus surmuletus and Diplodus sargus. Multivariate techniques showed that substrate slope and depth are abiotic factors that structure the community. Species richness and total abundance of individuals increased with depth and slope, whereas evenness decreased.
The reproduction and feeding habits of the Bastard grunt, Pomadasys incisus (Bowdich, 1825), in the Gulf of Tunis were investigated monthly from January to December 2003. An examination of the gonads ...of 463 specimens showed that the Bastard grunt is a gonochoric species and the sexratio wasn’t significantly different from 1:1. The monthly variations of the gonadosomatic index and the percentage of the different gonadal development stages revealed that P. incisus spawning period occurred from August to October. This species uses its energetic reserves contained in the liver and the muscles to assure gonadal maturation. The size at first maturity (L50) was estimated at 15.33 cm for both sexes pooled. The stomachs examined showed a high vacuity index throughout the year (56.8%) and presented a significant difference between seasons. The stomach contents analysis revealed that P. incisus’ diet was especially constituted of crustacean species as well as benthic and planktonic organisms that belong to 19 taxa. The percentage frequency of occurrence (F) computed for Crangon crangon, Hyperoche sp. and Geryon longipes (the most abundant prey in the diet) showed significant differences among seasons (χ2obs=31.228, 29.471 and 11.302 respectively, were superior to χ20.05).
Istraživane su reprodukcija i prehrambene navike morskog hroktača, Pomadasys incisus (Bowdich, 1825), u tuniskom zaljevu od siječnja do prosinca 2003. Istraživanje gonada na 463 uzorka je pokazalo da je morski hroktač gonohorična vrsta i da odnos među spolovima nije značajno odstupao od razmjera 1:1. Mjesečna kolebanja gonadosomatskog indeksa i postotka različitih stadija razvoja gonada otkrivaju da se P. incisus mrijesti od kolovoza do listopada. Ova vrsta koristi energetske pričuve iz jetre i mišića kako bi osigurala sazrijevanje gonada. Izračunata dužina pri stadiju 50% zrelosti populacije (L50) iznosila je 15.33 cm za oba spola ukupno. Analizirani sadržaj želuca je pokazao vrlo visoki indeks ispražnjavanja tijekom godine (56.8%) sa značajnom razlikom između sezona (godišnjih doba). Ustanovljeno je također da se prehrana P. incisus sastoji od rakova, bentičkih i planktonskih organizama iz 19 taksonomskih skupina. Postotak učestalosti pojavljivanja pronađen za Crangon crangon, Hyperoche sp. i Geryon longipes (najzastupljenije u prehrani) ukazuje na značajne razlike među sezonama (χ2obs= 31.228, 29.471 odnosno 11.302, a bile su veće od χ20.05).
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