Primeros datos sobre la reproducción y el crecimiento de Buenia affinis Iljin, 1930 (Gobiidae) en el Adriático norte

De Buen’s goby, Buenia affinis, is a very small Mediterranean goby (38.8 mm TL) inhabiting sandy infralittoral bottoms and known only from a few published records. Some aspects of reproduction and growth of B. affinis were investigated from a population collected in the Kvarner area (north-eastern Adriatic Sea). Sampling was carried out by SCUBA diving between May 2003 and April 2004. The sex ratio did not differ significantly. The estimated length at sexual maturity was 26.1 and 27.4 mm for females and males, respectively. The spawning season extended from February to July. The absolute fecundity (F) ranged from 457 to 714 eggs per individual (mean ± SE, 556 ± 25). Based on the length frequency distribution analysis throughout the year and seasonal growth bands on sagittal otoliths, B. affinis was assumed to be an annual species.El gobio de De Buen, Buenia affinis, es un minúsculo góbido mediterráneo (38.8 mm LT) que habita fondos arenosos litorales y del cual sólo hay unas pocas citas publicadas. Hemos investigado algunos aspectos de la reproducción y el crecimiento de B. affinis a partir de muestras de una población del área de Kvaner (Adriático nororiental). El muestreo se realizó mediante buceo con escafandra autónoma entre mayo de 2003 y abril de 2004. El sex ratio no presentó diferencias significativas. La talla estimada de madurez sexual fue de 26.1 mm para las hembras y de 27.4 mm para los machos. La época de puesta se extendió de febrero a julio. El rango de fecundidad absoluta (F) fue de 457 a 714 huevos por individuo (media ± SE, 556 ± SE). En base al análisis de la distribución de la frecuencia de tallas a lo largo del año y a las bandas de crecimiento de los otolitos sagitales, B. affinis parece ser una especie anual

Spatial patterns and behaviour of notothenioid fishes off the northern Antarctic Peninsula

A photographic seabed survey conducted off the Antarctic Peninsula region provided the opportunity to study spatial patterns, abundance and behaviour of the notothenioid benthic fish fauna. Overall, a total of 12,715 images taken with the Ocean Floor Observation System (OFOS) along 26 transects in three ecoregions (Joinville Island, Bransfield Strait and Drake Passage) were analysed. The fish fauna consisted of at least 34 species belonging to four families of both low-Antarctic and high-Antarctic origin. Nototheniids showed the highest relative abundance and species richness, followed by channichthyids, bathydraconids and artedidraconids. Direct in-situ observations in OFOS seabed images allowed descriptions of fish behaviour, such as aggregation of individuals (Notothenia coriiceps), specific body postures (Cygnodraco mawsoni and Cryodraco antarcticus) and parental care (Chaenodraco wilsoni, Chionodraco rastrospinosus, Pagetopsis macropterus and Trematomus hansoni). Fish density and species richness was primarily correlated with the occurrence of bryozoans, ascidians, and large cup-shaped sponges, providing a three-dimensional habitat suitable for fish settling, foraging, breeding and refuge from predators. Fish diversity was higher (a) off Joinville Island and in Bransfield Strait than in Drake Passage, where almost exclusively low-Antarctic species were recorded, and (b) between 100 and 600 m than at greater depths. Overall, the benthic fish fauna off the northern Antarctic Peninsula is zoogeographically composite and widespread, with well-structured spatial partitioning

Edad y crecimiento del rascacio, Scorpaena porcus (Pisces: Scorpaenidae) en estructuras artificiales y arrecifes naturales en el mar Adriático

Age and growth of the black scorpionfish, Scorpaena porcus, were estimated for different populations inhabiting natural reefs and artificial structures (artificial reefs and offshore gas platforms) in the northwestern Adriatic Sea. Annual growth increment counts were carried out on sagittal otoliths of 415 specimens ranging from 80 to 280 mm TL. The accuracy of age estimates was assessed by testing the annual deposition of annuli and the location of the first annulus by marginal increment analysis and daily growth increment counts, respectively. As commonly observed in other scorpaenids, annuli consisted of an alternating pattern of opaque and translucent zones. Marginal increment analysis confirmed that annuli are formed once a year, with opaque zones laid down in spring-summer and translucent zones laid down in autumn-winter. The precision of age estimates was tested by applying both the average percent error (APE) and the mean coefficient of variation (CV). The maximum age estimated for the whole sampled populations was 8 years. The von Bertalanffy growth curves were separately fitted for natural and artificial reef populations of S. porcus. The likelihood ratio test indicated that the overall von Bertalanffy growth curves differed significantly between the two populations. The instantaneous growth rate (k, year-1) and asymptotic length (L∞, cm) were 0.23 and 22.30 and 0.53 and 20.13 for natural and artificial reef populations, respectively. Compared with natural reef population, populations of S. porcus inhabiting artificial reefs and, particularly, offshore platforms, were characterized by larger and older fish. However, young-of-the-year were completely absent from the platform habitats. The effects of artificial structures on S. porcus populations in the study area are discussed in the light of previous results on scorpionfish living in other areas.Se estimó la edad y crecimiento del rascacio, Scorpaena porcus, de diferentes poblaciones de arrecifes naturales y estructuras artificiales (arrecifes artificiales y plataformas de gas a mar abierto) en el noroeste del mar Adriático. Los contajes de los incrementos de crecimiento anuales se realizaron en otolitos sagitta de 415 especímenes entre 80 y 280 mm de longitud total. La precisión de la estima de la edad se evaluó comprobando la formación anual de los anillos, y la localización del primer anillo mediante análisis de incrementos marginales y contajes de incrementos diarios, respectivamente. Tal como es comúnmente observado, los anillos presentan un patrón de zonas opacas y translúcidas que van alternando. El análisis de incrementos marginales confirmó que los anillos se forman una vez al año, con las zonas opacas que se depositan en primavera-verano y las translúcidas en otoño-invierno. La precisión en la estima de las edades se comprobó aplicando el porcentaje de error promedio y el coeficiente promedio de variación (CV). La edad máxima estimada para todas las poblaciones muestreadas fue de ocho años. Las curvas de crecimiento de von Bertalanffy growth se ajustaron separadamente para las poblaciones de S. porcus de arrecifes naturales y artificiales. El test de verosimilitud indicó que las curvas de crecimiento de von Bertalanffy diferían significativamente entre las dos poblaciones. La tasa instantánea de crecimiento (k, año-1) y la longitud asintótica (L∞, cm) fueron 0.23 y 22.30 y 0.53 y 20.13 para poblaciones de arrecifes naturales y artificiales, respectivamente. En comparación con las poblaciones de S. porcus de arrecifes naturales, las que se encuentran en arrecifes artificiales y, en particular en plataformas a mar abierto, se caracterizaron por peces más grandes y de más edad. No obstante, los individuos de edad inferior a un año están completamente ausentes en dichas plataformas. El efecto de estructuras artificiales en las poblaciones de S. porcus en el área de estudio se discuten en función de resultados previos de scorpeniformes de otras áreas

Starost i rast ranih razvojnih stadija srdele (Sardina pilchardus) u zapadnom Jadranu

Age and growth of early life stages of sardine, Sardina pilchardus, were investigated by microincrement counts on sagittal otoliths. Postlarval and juvenile specimens were collected in the coastal waters off Ortona (central Adriatic Sea) from December 1996 to May 1997. Otolith microstructure analysis was conducted on 286 specimens ranging from 30 to 68 mm TL. Age estimates ranged from 65 to 151 days. The precision of age estimates was tested by applying both the average percent error (APE) and the coefficient of variation (CV). The hatch date distribution, back-calculated from the date of capture, was spread over a long period lasting from September to March, with two main cohorts hatched in autumn (October) and winter (February), consistently with a long spawning season reported for this species. Applying the Gompertz growth model to the age-length data set, a growth curve was obtained for each cohort. The mean absolute daily growth rate was 0.33 mm day-1and 0.22 mm day-1 for the autumn and winter cohorts, respectively. Otolith growth increment patterns was rather similar in the two cohorts, but they differed for the amplitude and timing of increment width deposition, being otoliths accurate proxies of larval fish growth rate. Strong seasonality of environmental features, such as water temperature and food resources, and endogenous factors linked to the larval ontogeny, largely contributed to affect the early life history stages of sardine.Istraživani su starost i rast ranih razvojnih stadija srdele Sardina pilchardus, te mikro prirast na sagitalnim otolitima. Ličinke i juvenilni uzorci prikupljeni su u obalnim vodama Ortone (srednji Jadran) od prosinca 1996. do svibnja 1997. godine. Analiza mikrostrukture otolita provedena je na 286 jedinki u rasponu od 30 do 68 mm ukupne dužine (TL). Procijenjena starost kolebala je od 65 do 151-og dana. Preciznost procjene starosti testirana je primjenom prosječnog postotka pogreške (APE) i koeficijenta varijacije (CV). Datum izvaljivanja ličinki bio je naknadno izračunat prema datumu ulova koji traje od rujna do ožujka, s dvije glavne skupine koje su se izvalile u jesen (listopad) i tijekom zime (veljača), konzistentno s ustanovljenom dugom sezonom mrijesta za ove vrste. Primjenom Gompertz modela rasta na skup podataka o starosno-duljinskom odnosu dobivena je krivulja rasta za svaku skupinu. Apsolutna srednja vrijednost dnevnog rasta iznosila je 0.33 mm dan-1 i 0.22 mm dan-1 za jesenske i zimske skupine, respektivno. Prirast otolita bio je prilično sličan u dvije skupine, mada se razlikovao s obzirom na vrijeme formiranja i učestalost istih. Jak utjecaj sezonskih ekoloških značajki, kao što su temperatura vode i izvor hrane, te endogeni čimbenici povezani s ontogenezom ličinki, u velikoj mjeri utječu na rane razvone stadije srdele

Life history traits and historical comparison of blue whiting (Micromesistius poutassou) growth performance from the western Pomo/Jabuka Pits area (central Adriatic Sea)

Although fishing is considered the primary cause of the decline in fish populations, increasing evidence of the significant role of climate change has been provided recently in the Mediterranean Sea, which shows one of the highest warming trends in the world. In this area, the most important environmental driver is represented by the increase in seawater temperature. Though several studies have addressed the effects of sea warming on thermophilic species, little attention has been paid to cold-water species. Among these, blue whiting (Micromesistius poutassou) constitutes one of the most important traditional fisheries resources in the northern part of the basin, particularly in the central Adriatic Sea. This area has experienced intense fishing exploitation by the Italian and Croatian fishing fleets. Since 2015, the Pomo/Jabuka Pits area, the fleets' main fishing ground, has been subject to a series of fishing regulations over time and space. In the present study, we investigated the age structure and growth performance (by means of otoliths) of blue whiting, comparing samples collected during 1985-86 and 2020-21 in the Pomo/Jabuka Pits. Our results show that the 2020-21 blue whiting specimens had a lower length-at-age compared to 1985-86. The asymptotic length estimate decreased from 29 cm TL in 1985-86 to 25 cm TL in 2020-21. The pattern observed might be related to a modification in the cold and dense water formation dynamics in the northern Adriatic Sea, as a consequence of climate change, resulting in higher temperatures and lower nutrient and oxygen exchange, which may have hampered the optimal growth of the species. Moreover, data on the historical trend of landings from the Adriatic Sea reveals a clear decline in catches starting from 2000 onwards. Although the introduction of a fishing ban in the Pomo/Jabuka Pits was an important milestone, the abundance of this species in the area remains at low levels, highlighting a potentially alarming situation for the stock of blue whiting in the central Adriatic Sea

Reproductive traits and age of barbeled plunderfishes from the Weddell Sea

AbstractThe genus Pogonophryne is the most species-rich genus of barbeled plunderfishes (Artedidraconidae) and includes more than 25 poorly known species endemic to the Southern Ocean. In this study, we provide new data on the age and reproductive traits of some species of Pogonophryne from the southern Weddell Sea, inferred through otolith reading and histological analyses of gonads. Individual age estimates ranged between 16 and 18 years for Pogonophryne barsukovi and Pogonophryne immaculata and between 10 and 22 years for Pogonophryne scotti. As is commonly found in notothenioids, P. barsukovi followed a group-synchronous type of ovarian development, with pre-vitellogenic and vitellogenic oocytes forming two well-separated egg-size groups. A single spawning female in the sample produced ~1097 eggs and 7.9 eggs g-1. The sample of P. immaculata consisted exclusively of developing males, with testes composed of cysts of spermatogonia, spermatocytes and spermatids. Pogonophryne scotti was the most abundant species, including relatively small males at immature or developing stages of gonad development. Larger females were regressing, being characterized by ovaries with postovulatory follicles and atretic oocytes. Based on the macroscopic and histological analyses of gonads, the spawning season would take place in autumn for P. barsukovi and P. immaculata and in spring–early summer for P. scotti

First data on reproduction and growth of <i>Buenia affinis</i> Iljin, 1930 (Gobiidae) in the northern Adriatic Sea

De Buen’s goby, Buenia affinis, is a very small Mediterranean goby (38.8 mm TL) inhabiting sandy infralittoral bottoms and known only from a few published records. Some aspects of reproduction and growth of B. affinis were investigated from a population collected in the Kvarner area (north-eastern Adriatic Sea). Sampling was carried out by SCUBA diving between May 2003 and April 2004. The sex ratio did not differ significantly. The estimated length at sexual maturity was 26.1 and 27.4 mm for females and males, respectively. The spawning season extended from February to July. The absolute fecundity (F) ranged from 457 to 714 eggs per individual (mean ± SE, 556 ± 25). Based on the length frequency distribution analysis throughout the year and seasonal growth bands on sagittal otoliths, B. affinis was assumed to be an annual species

Spatial distribution and habitat preferences of demersal fish assemblages in the southeastern Weddell Sea (Southern Ocean)

Our knowledge on distribution, habitats and behavior of Southern Ocean fishes living at water depths beyond scuba-diving limits is still sparse, as it is difficult to obtain quantitative data on these aspects of their biology. Here, we report the results of an analysis of seabed images to investigate species composition, behavior, spatial distribution and preferred habitats of demersal fish assemblages in the southern Weddell Sea. Our study was based on a total of 2736 high-resolution images, covering a total seabed area of 11,317 m2, which were taken at 13 stations at water depths between 200 and 750 m. Fish were found in 380 images. A total of 379 notothenioid specimens were recorded, representing four families (Nototheniidae, Artedidraconidae, Bathydraconidae, Channichthyidae), 17 genera and 25 species. Nototheniidae was the most speciose fam- ily, including benthic species (Trematomus spp.) and the pelagic species Pleuragramma antarctica, which was occasionally recorded in dense shoals. Bathydraconids ranked second with six species, followed by artedidraconids and channichthyids, both with five species. Most abundant species were Trematomus scotti and T. lepidorhinus among nototheniids, and Dol- loidraco longedorsalis and Pagetopsis maculatus among artedidraconids and channichthyids, respectively. Both T. lepi- dorhinus and P. maculatus preferred seabed habitats characterized by biogenous debris and rich epibenthic fauna, whereas T. scotti and D. longedorsalis were frequently seen resting on fine sediments and scattered gravel. Several fish species were recorded to make use of the three-dimensional structure formed by epibenthic foundation species, like sponges, for perching or hiding inside. Nesting behavior was observed, frequently in association with dropstones, in species from various families, including Channichthyidae (Chaenodraco wilsoni and Pagetopsis macropterus) and Bathydraconidae (Cygnodraco mawsoni)