Mugil liza is distributed along the western Atlantic coast. It is a commercially exploited species in Argentina, supporting a small-scale fishery conducted by an artisanal fleet. Age determination of fishes constitutes an important key issue for fishery management. The age, growth and recruitment of M. liza juveniles in Mar Chiquita coastal lagoon and Las Brusquitas creek (Buenos Aires, Argentina), were estimated by means of the analysis of the sagittal otoliths of fish collected during January to December of 2014. Ages were estimated by counting and measuring daily growth increments in otoliths under a light microscope. A total of 735 specimens ranging from 19 to 71.5 mm SL and from 67 to 212 days age was analysed. Lengths at previous ages were determined by back-calculation, a linear growth model was fitted to the back-calculated data: SL = 0.2468 + 2.0516; R2 = 0.9945. Two peaks of recruiters were observed from February to March, and from October to November in 2014. Mean ages in days of Querimana and juveniles at the recruitment time were 84.07 ± 14.43 days and 87.56 ± 19.51 days, respectively. The hatching dates of specimens showed two spawning seasons. One was from December 2013 to January 2014, and the second one from July to August 2014. The assessment carried on this work generated age determination values that support previous findings, contributing to make a more accurate description of the life-history model currently used. In addition, valuable information has been generated to give better advice for improving the management of the fishery resource.

The present work expands the existing knowledge on M. mola ecology by assessing, for the first time, its abundance (and body size distribution) in the southern waters of Portugal and relating the associated temporal variations with environmental variables. There were significant seasonal differences in abundance, with peaks in spring and autumn and lower values throughout the summer. Ocean sunfish abundance was positively correlated with sea surface temperature and chlorophyll a, indicating that a combination of both temperature and productivity dictates spatial use. Complementarily, the absence of a relationship between abundance and water transparency may reveal a strategy in spatial use favouring a medium-term steady food supply over short-term improved feeding opportunities. Specimens ranged between 31.8 and 230.0 cm (total length), with 98% of all individuals measuring between 31.8 and 59.9 cm. As the vast majority of specimens analysed were immature, seasonal differences in abundance should not be related to spawning.

Despite the important ecological roles of commercial bêche-de-mer holothuroids in coral reef ecosystems their reproductive biology is poorly studied, including on the Great Barrier Reef (GBR). We investigated reproduction of Stichopus herrmanni, a commercially important species listed as Vulnerable, at One Tree Island, southern GBR. Gonad index, histology and spawning observations indicated an annual reproductive cycle with gamete release in the Austral spring and summer (November–February), as for populations of this species at a similar latitude in New Caledonia. Stichopus herrmanni releases gametes episodically, spawning multiple times during summer. Assimilation of spawning observations from OTI and elsewhere along the GBR and tropical Pacific revealed that gamete release by S. herrmanni is influenced by the lunar cycle, with spawning taking place around the new moon in summer. This species is an aggregative spawner with a behavioural change to attain elevated positions on the reef at dusk prior to spawning. After the spawning season, gametes remaining in the gonads are reabsorbed. Spent gonads completely lacked gametes. There was a quiescence in gonad development in winter with an absence of gonads in some specimens, indicating an aestivation-like period for reproduction. By late-winter (August) recovery stage gonads were distinguished by the initiation of gametogenesis, which coincided with increasing temperature and day length. Our findings contribute to the understanding of the reproductive biology of S. herrmanni, a consideration for future fisheries management in the protection of this Vulnerable species, especially with respect to the increasing global trade in bêche-de-mer.

The spatial and temporal variability in the relative abundance of the post-larvae (PL) and juvenile (JU) stages of the pink shrimp Farfantepenaeus paulensis was investigated in the estuary of Lagoa dos Patos, southern Brazil. This analysis enabled the identification of differential distribution patterns. Pink shrimp abundance was studied to understand what factors influence the occupation of the estuary. Monthly samples were taken with a trawl net at 12 sites in the estuary from September 2010 to January 2013. Comparisons were made between protected and unprotected sites. Both PL and JU had a wide distribution in the estuary. The temperature was not a significant variable for explaining abundance variability. The abundance of PL increased with salinity and influenced PL entry to the estuary. The highest abundances of PL were found in unprotected areas and protected sites at the mouth of the estuary, while juveniles were unevenly distributed with higher abundance in protected areas. Recruitment period of PL in the estuary was October to March, and of juveniles was November to February. We suggest that the preservation of unprotected shallow waters and protected areas at the mouth of the estuary are key to further recruitment of the species in the estuary.

This study documents the presence of crypsis in Mugil curema juveniles under laboratory culture. Initially, the juveniles were located in one brown tank (BT1), later almost half of the individuals were placed in a white tank (WT) where they showed a pigmentation change to white. After being moved to another brown tank (BT2), the juveniles changed to their brown original colour, but kept a few small white spots on the dorsal axis of the body. The ventral head melanophore pattern also changed in the white specimens. Temperature (°C), oxygen (mg l−1) and Illuminance light (Lux m−2), total length (mm) and total weight (g) were determined by tank. Chromaticity was measured in L*(relative luminance) a*(measurement relating to the redness or greenness of the light) b*(measurement relating to the yellowness or blueness of the light) coordinates where all three values are required to completely describe an object’s colour. One-way ANOVA showed no differences for temperature, oxygen and illuminance light among tanks. Length and weight were similar for BT1 and WT but both were different from BT2. The white juveniles depicted similar L* as the WT background as well as the dorsal area of the brown pigmentation and converted juveniles to the brown tanks BT1 and BT2, respectively. Therefore, the fish's body relative luminance matches the background. To our knowledge this behaviour has not been reported before for any fish mullet either cultured or living in the wild.

During the summer of 2013 two scientific surveys (northern, at the beginning of July and southern, at the end of July) were carried out along the eastern Adriatic Sea. In these surveys, ichthyoplankton samples of anchovy (Engraulis encrasicolus, Linnaeus 1758) eggs and larvae were collected. In the whole investigated area, egg and larvae abundance varied from 2.61 to 1040.24 eggs m−2 (geometric mean ± CL: 25.43 ± 1.48 eggs m−2) and 2.73 larvae m−2 to 611.14 larvae m−2 (geometric mean ± CL: 17.07 ± 1.41 larvae m−2), respectively. Higher abundance of anchovy early life stages was noted in the northern part of the investigated area. The length of the collected specimens lay within the range of 2.39–3.68 mm and those individuals were less than 12 h old. Analysis of spatial and temporal distribution of collected anchovy early life stages indicated their higher abundance in areas of upwelling (four areas were distinguished on the eastern Adriatic side). Larger and older specimens were collected at the beginning of July in the northern part of Adriatic indicating that the anchovy population in the Adriatic tends to shift among its spawning centres in this area. In general, anchovy eggs were accompanied by its larvae (r = 0.453, P < 0.05), while statistically significant negative correlation was obtained between egg abundance and temperature (r = −0.380, P < 0.05) as well as sea depth (r = −0.321, P < 0.05).

The eastern North Atlantic (ENA) has many highly productive areas where several species of cetaceans have been recorded, with the common dolphin (Delphinus delphis) being one of the most frequently sighted species. However, its spatial and temporal distribution in high seas is poorly known. The study presents the results from 5 years of cetacean monitoring in the ENA (2012–2016) aboard cargo ships that follow the routes from Continental Portugal to the Macaronesian archipelagos and north-west Africa. Common dolphin was the most frequently sighted cetacean with 192 occurrences registered on effort and an overall encounter rate of 0.36 sightings/100 nmi. The species was distributed in coastal and offshore waters, but absent from the Canaries and Cape Verde islands. Statistical ‘habitat’ models were developed to describe and explain the occurrence of sightings of the species: variables affecting detection of dolphins had a small impact and there were clear spatiotemporal distribution patterns, influenced to some degree by environmental variables. Predicted probability of occurrence was highest in coastal waters of continental Portugal and around the Azores. The models, combined with maps of distribution, were useful to identify important areas for the species, which could be the focus of future conservation efforts. Common dolphin presence was related to depth, distance to coast and seamounts, seabed slope, chlorophyll concentration, sea-surface temperature and sea level anomalies; the possible ecological significance of these relationships is explored.

Four new malformations observed in blue shark embryos in the western coast of Baja California Sur, Mexico are reported in this study. The embryos of blue shark samples were obtained on board the industrial fishing boat ‘Damasta’; the organisms were frozen and transferred to CIBNOR Fish Ecology Laboratory where the corresponding measurements were taken and malformations observed. The first malformation was the presence of one nostril in two female embryos that showed short and crushed snouts. The second one was observed in a female with two jaws and the middle portion of the column trunk in screw-shape. The third one was an embryo with dicephaly, two separate vertebral columns, two first dorsal fin pairs, absence of the second dorsal fin, five pelvic fins and two joint caudal fins. The fourth malformation observed was an embryo with incomplete development and undifferentiated sex. Malformations are still a mystery and also an object of study because they affect different organisms, not only sharks but also fish. It is highly relevant to know the causes and perform further studies to understand if the origin is either genetic or anthropogenic.

Coastal ecosystems have been increasingly subjected to poor water quality. Remote sensing has been used to monitor water quality, but few studies have integrated remotely sensed data with compositional and/or abundance data of coral reef taxa. In the present study, fish biomass was assessed along the Jakarta Bay Thousand Island reef system and variation in the biomass of selected fish families related to substrate cover and remotely sensed data. Overall, fish biomass and the biomass of each of the families Acanthuridae, Apogonidae, Caesionidae, Chaetodontidae, Ephippidae, Pomacentridae, Labridae and the subfamily Scaridae were much higher mid- and offshore than inshore. Substrate cover and chlorophyll-a concentrations proved to be significant predictors of spatial variation in fish biomass, suggesting an important impact of reef degradation and eutrophication on reef fish abundance.

We examined the feeding ecology (diet, trophic width and trophic position) of five demersal shark species (Mustelus mustelus Linnaeus, 1758, Galeus melastomus Rafinesque, 1810, Scyliorhinus canicula Linnaeus, 1758, Scyliorhinus stellaris Linnaeus, 1758, Squalus blainville, Risso, 1826) coexisting in the north-eastern Aegean Sea (around Gökçeda Island) by combining stomach content and stable isotope analyses. The results indicate clear differences in diet between the five sharks. Cephalopods were mainly found in diet of S. stellaris and M. mustelus and the stomachs of G. melastomus, S. canicula and S. blainville included fish. S. blainville showed the highest trophic position in respect of stable isotope analysis (TPsia = 4.89) around Gökçeada Island. It was followed by G. melastomus (TPsia = 4.57). Direct isotopic values (both stable nitrogen and carbon) and isotopic niche width based on the Standard Ellipse Area (SEA) clearly differed among the five shark species. In particular, S. blainville was isotopically segregated from the other shark species studied, showing a narrow isotopic trophic niche and higher trophic level. In contrast, M. mustelus had the widest trophic niche of the five species studied. The niche width of S. stellaris was narrower than M. mustelus and S. canicula but wider than S. blainville and G. melastomus. SEA showed that G. melastomus has a specialized feeding strategy in the area. There is no overlap between S. canicula and S. stellaris in trophic width.

Nephrops norvegicus is a commercially valuable demersal fisheries species. Relatively little is understood about this species’ population dynamics across its distribution with previous mitochondrial and microsatellite studies failing to identify significant population-level differentiation. In this study, sequence variation in the mitochondrial (mtDNA) D-loop was analysed from samples across the distribution range, and compared with COI sequences for this species retrieved from GenBank. Analysis of a 375 bp fragment of the D-loop revealed significant genetic differentiation between samples from the North-east Atlantic and the east Mediterranean (FST = 0.107, P < 0.001). Tau (τ), theta (θ0 and θ1) and Fu's FS values suggest the species spread between 10,500 to 19,000 ybp and subsequently expanded rapidly across the Atlantic.

Cephalopods are important prey in the diet of top predators, such as marine mammals and seabirds. However, detailed information on their trophic relationships in the Patagonian marine ecosystem is scarce, including those cephalopod species with commercial interest. The aims of this study were to evaluate the composition of the cephalopod component in the diet of Otaria byronia and determine the habitat use and trophic levels of their main cephalopod prey by measuring the stable isotopic signature of cephalopod beaks. Between May 2005 and February 2009, fresh faecal samples were collected from two sea lions rookeries in San Matias Gulf. Cephalopods occurred in 39.4% of the 1112 samples collected during the whole period of study. The dominant prey species was Octopus tehuelchus, which occurred in 45.8% of scats containing cephalopod remains, and represented 58.7% in terms of numerical abundance and 52.0% in mass of cephalopods consumed. The second species most consumed was the myopsid Doryteuthis gahi. The significant higher δ15N values of O. tehuelchus beaks in comparison with those of D. gahi showed that these two species have different trophic levels while occupying similar habitat (δ13C values) in neritic waters of the Patagonian shelf.

The genus Acanthogobius of gobiioid fish has been reported for six species from East Asia, and inhabits estuarine and coastal waters. Within this genus, Acanthogobius insularis is an endangered and endemic goby in the Amami-oshima and Okinawa-jima Islands, southern Japan, and its range is restricted to the lowermost course of a few river basins. Basic knowledge on this species is scarce in spite of its vulnerable conservation status. The purpose of this study was to elucidate the life history of A. insularis. Monthly sampling was conducted at five stations in the Taiho River, Okinawa-jima Island, from November 2014 to November 2015. Monthly standard length (SL) distributions were unimodal except in April during the recruiting period, suggesting that A. insularis is an annual species. Analysis of the gonadosomatic index and histological observations of the ovaries revealed that this species spawns from January to May. The beginning of the spawning season seems to be related to a decline in water temperature in December. Growth rates appeared to be lower from April to December and higher in winter months. From monthly collections, A. insularis was found to move upstream with growth, and gather at spawning grounds during the reproductive season. Acanthogobius insularis might be threatened by increasing water temperature due to climate change, since low water temperatures appear to be important for their reproduction and growth. Moreover, habitat diversity, from tidal flats for recruiting grounds to upstream sites with cobbles for spawning, is needed to complete their life cycle, and should be conserved.

The paper presents the first detailed study on systematics, otolith structure and biology of Diaphus coeruleus, from the south-eastern Arabian Sea. The closely related and co-inhabiting species D. coeruleus and D. watasei are distinguished on the basis of morphometric, meristic and otolith characters. Analysis of gut content revealed that these fishes mainly feed on deep sea squids and shrimps. Six maturation stages of gonads are identified in males (immature, quiescent, mature, ripe, spawning and spent) and five stages (immature, quiescent, mature, ripening and spawning stages) in females. Overall sex ratio deviated in favour of males (1 male: 0.2 female) and the mean fecundity was 2150 ± 353 eggs. The length-weight relationship shows an overall isometric growth in males with N = 76 and b = 3.13 and for females with N = 17 and suggests negative allometric growth (b = 1.719). Otolith length (LO) and otolith weight (WO) are positively correlated to standard body length (LS) and body weight (BW).