During the period from April to September for the years 2014–2016, 998 swordfishes caught by the Moroccan artisanal longline fishery in the Strait of Gibraltar were sampled to study the reproduction of this species in this mixing area between the Mediterranean Sea and the North Atlantic. The results showed that the sex ratio is slightly in favour of males for sizes smaller than 130 cm LJFL (Lower jaw-fork length), whereas females are more numerous in sizes larger than 140 cm LJFL. Fifty per cent of females were estimated to be mature at 170 cm LJFL, while for males, the size at first maturity was estimated to be 95 cm LJFL. The swordfish spawn from June to September, probably in the Mediterranean Sea. The findings of this study suggest that the reproductive characteristics of swordfish caught in the Strait of Gibraltar are similar to those of the Mediterranean swordfish, and a high mixing rate between the Mediterranean and the North Atlantic stocks occurs in the study area.

This paper provides data on diversity, zonation and seasonal fluctuations of decapod crustaceans at the northern Gulf of Oman coast, based on quantitative and qualitative samplings. A total of 75 species belonging to four infraorders, 27 families and 48 genera were identified. These species include 20 new records for the entire Gulf of Oman and 13 new records for its Iranian coast. The mid-intertidal zone showed a higher mean diversity and abundance than high- and low-intertidal zones. The mean diversity and abundance in the high-intertidal zone showed significant differences with the mid- and low-intertidal zones. The indices of species richness (Margalef), diversity (Shannon) and evenness (Pielou) showed significant differences among the intertidal zones. Most of the identified species (>60%) that had high values in their frequency of occurrence and relative abundance showed an overlapping vertical distribution, and were present in all three or just in two of the three defined zones. Other species were found only in one of the three zones (non-overlapping vertical distribution). The decapod community in the mid-intertidal zone showed a higher dissimilarity with the high-intertidal zone than with the low-intertidal. Both abundance and diversity were found to be lowest and highest during south-west and north-east monsoons, respectively. During south-west monsoon, the abundance of decapods declined dramatically, but species diversity and ecological indices did not show any statistically significant difference among the sampling periods.

Sampling at four salmon aquaculture sites along the west coast of Scotland has identified short-lived aggregations of planktonic hydrozoans (>280 individuals m−3), here termed blooms. Several such blooms were linked with increases in gill pathology and mortality in caged fish. Two types, Obelia sp. and Lizzia blondina, were found to cause blooms regularly and often concurrently. Species composition of hydrozoan populations and fluctuations in population sizes were spatially and temporally heterogeneous, with adjacent sites (within 30 km of one another and with similar oceanic exposure) experiencing no correlation between species composition and population density. Blooms appeared temperature-mediated, with all identified blooms by Obelia sp. and L. blondina taking place in water above 12 °C; however, temperature alone was not found to be predictive. Blooms were not significantly associated with change in salinity, water clarity, or photoperiod. Due to the apparent lack of broadly applicable predictors, we suggest that localized, targeted sampling and examination of planktonic hydrozoan populations is required to discern the presence or absence of a bloom. It is likely that many blooms have historically caused harm in salmon aquaculture while remaining unrecognized as the root cause.

This study describes the structure, growth, mortality and stock status of Litopenaeus schmitti in north-eastern Brazil. A total of 1169 specimens were captured (491 males and 678 females) from August 2011 to July 2012. Specimens were weighed and the length of carapace (CL) and total length were measured. The biometric relationships were estimated through regression analysis and growth was described through the von Bertalanffy model. Additionally, total mortality (Z), natural mortality (M), fishing mortality (F), length at first capture (Lc), maximum yield per recruit (ERMY) and longevity were determined. Females were larger (3.07 ± 0.51 cm) than males (2.68 ± 0.25 cm) and dominant in the largest CL classes. The biometric relationships for males, females and both sexes grouped showed a negative allometric growth. Females showed larger L∞ (asymptotic length) and k (coefficient of growth) (L∞ of 5.00–5.16 cm and k of 1.20–1.26 year−1) when compared with males (L∞ of 4.25–4.30 cm and k of 1.00–1.02 year−1). In general, the mortality of males (Z = 1.93–5.48 year−1; M = 1.59–1.61 year−1 F = 0.32–0.3.89 year−1) and longevity (1.11–2.16 years) were higher than those estimated for females (Z = 1.84–3.76 year−1; M = 1.70–1.77 year−1; F = 0.07–1.99 year−1; 1.07–1.78 years). Results indicated that L. schmitti stock is relatively close to the state of full exploitation. Moreover, the CL of first capture of females (2.44–2.51 cm) is below the length of first sexual maturation of the species. The lack of legislation governing shrimp fishing in the area makes this stock even more vulnerable.

During the INDEMARES/CHICA 0610, 0211 and 0412 expeditions, carried out in the northern Spanish sector of the Gulf of Cádiz (Spain), samples were collected with a box-corer in 11 mud volcanoes and their adjacent bottoms. Chemoautotrophic communities were found in nine mud volcanoes. Among Decapoda, a rare eucalliacid, belonging to the genus Calliax and related to the Mediterranean infralittoral species C. lobata (de Gaillande and Lagardère 1966), was present in three of them. Data on its morphology, biogeographic distribution, vertical distribution within the burrows, sediment composition, pH and redox potential values (each in 5 cm intervals) are given; information on the chemoautotrophic communities associated with this species are also provided.

Rock oysters of the genus Saccostrea are the dominating group of filter-feeding communities on rocky beaches worldwide. The edible rock oyster (Saccostrea cucullata) is used as food and fish bait along the Indian coast. Morphometric analyses of S. cucullata from Baindur, Karnataka (India) were performed from June 2010 to May 2011, aiming to establish relationships between length and weight (total weight, shell weight, meat wet weight and meat dry weight). Morphometric relationships between length (L)-breadth (B) and length (L)-width (W) were B = 6.4952 + 0.4619 L and W = 3.1806 + 0.3276L, respectively. The equations of the length (L)-total weight (TW), length (L)-shell weight (SW), length (L)-meat wet weight (WW) and length (L)-meat dry weight (DW) were TW = 0.001227L2.3973, SW = 0.001165L2.3164, WW = 0.000037L2.1327 and DW = 0.000030L2.3289, respectively. The allometric growth pattern revealed changes in shell shape and weight variation throughout ontogeny in rocky habitats. The condition index and meat yield of S. cucullata exhibited seasonality, with higher values recorded during the periods post-monsoon and pre-monsoon.

We examined the diet of pelagic juveniles of Trachurus japonicus in the surface layer in April, and subsequent demersal juveniles in the near bottom layer during May to June of the East China Sea (ECS) in 2005, 2008 and 2009. Diet composition of the pelagic juveniles showed a significant difference between 2005 and the other two years. That is, they preyed mainly on Paracalanus parvus s.l. and occasionally on Calanus sinicus in 2008 and 2009, while they fed mainly on Corycaeus affinis in 2005, partly corresponding with the between-year difference in prey densities. The demersal juveniles depended heavily on the fifth copepodites and females of C. sinicus which store lipids in the body, i.e. high-energy food for the juveniles, without a significant inter-annual difference. The markedly low occurrence of P. parvus s.l. and C. sinicus, which are considered to be energetically more favourable than C. affinis, from the stomach of the pelagic juveniles in 2005 corresponded with the lowest growth rates of the pelagic juveniles in the three years. Potentially, this resulted in the lowest observed recruitment level of the demersal juveniles for the ECS in 2005 over these three years.

The functional morphology of Pinna nobilis is described, with special reference to the uniquely pinnid pallial organ, the similarly unique buccal (formerly pallial) gland, the stomach and its contents. The pallial gland produces sulphuric acid which as well as functioning as a shell cleaning swab may be involved in prey capture. The buccal gland discharging into the oesophagus has proteolytic digestive functions while the stomach is adapted for the reception and digestion of captured, mucous-bound, mesozooplanktonic and epi- and endo-benthic, prey items. Pinna nobilis is thus not simply either an accidental or incidental predator of such species but is opportunistic. The buccal glands and stomachs of other Pinnidae are not so specialized as in P. nobilis, possibly indicating that in the particular, oligotrophic, environment of the Mediterranean and Adriatic Seas, and in which it is endemic, P. nobilis has, in addition to being a typical ctenidial suspension feeder, become an opportunistic predator. Although the deep sea representatives of the Septibranchia (Anomalodesmata) and Propeamussidae are obligate predators, this is the first record of any bivalve functioning as an opportunistic predator with unique morphological adaptations to facilitate this.

Based on some coincident morphological characters and distribution, it was believed for a long time that Mica micula was the post-larval stage of a species of Bargmannia, a genus having a very wide geographic distribution. Recent studies, however, have shown that it is much more likely to be the post-larval form of the physonect Pyrostephos vanhoeffeni, which is very common in both Antarctic and sub-Antarctic waters. Until now, molecular evidence to support this theory has been lacking. In the present study 34 nectophores of P. vanhoeffeni and four colonies of M. micula collected from three areas in the Southern Ocean were analysed for the 16S rRNA gene. Five haplotypes were identified, which formed two clearly distinct lineages. Three haplotypes were found exclusively in Admiralty Bay and were shared between individuals of both studied taxa, confirming that M. micula is indeed the post-larval stage of P. vanhoeffeni. Two additional haplotypes were found in one open ocean locality and in Admiralty Bay.

This study addresses aspects of the phylogenetic relationships of the commercial Tehuelche scallop, Aequipecten tehuelchus s.l. (Bivalvia: Pectinidae), from southern South America using molecular techniques. The Tehuelche scallop presents two different putative subspecies, A. t. tehuelchus and A. t. madrynensis, and a potentially related sympatric species, Flexopecten felipponei. The Tehuelche scallop is a very important component of ecosystems and is the target of artisanal fisheries in the northern Patagonian gulfs of Argentina. Despite its importance, the systematic relationships of these taxa have not been fully addressed. The main goal of this study is to place the Tehuelche scallop within a partial phylogenetic framework of the family Pectinidae. Scallops were sampled at 10 localities distributed along the south-western Atlantic Ocean. Phylogenetic reconstructions were carried out from two mitochondrial (12S rRNA and 16S rRNA) and two nuclear markers (28S rRNA and H3) using Bayesian, maximum likelihood and maximum parsimony analyses. Our phylogenetic analysis indicates that the two putative subspecies of the Tehuelche scallop together with F. felipponei form a monophyletic clade, without differentiating at the specific level. Observed differences would be the result of phenotypic plasticity, probably caused by environmental factors. However, further analysis using genes with faster evolution rate are needed to corroborate it. Our phylogenetic analysis resolved to Aequipecten as polyphyletic. The Tehuelche scallop has a basal position within the Argopecten group and we recommend that it should be transferred to this genus. The relationship between the hypotheses about the origin of the Tehuelche scallop implicit in the literature and our results are discussed.

The potential use of fatty acid (FA) profile as a dietary tracer in juvenile Chinese horseshoe crab Tachypleus tridentatus was assessed in a feeding experiment. Selected feed was provided to the juveniles at various growth stages according to their food sources in the wild: larval and adult brine shrimp Artemia salina for the first six months, followed by a mixture of short-neck clam Ruditapes philippinarum and greasyback shrimp Metapenaeus ensis for a further six months. Juvenile horseshoe crab haemolymph and tissues of book gill, opisthosomal spine, chelicera and swimming leg were sampled after the feeding experiment. The FA profiles revealed that the juvenile haemolymph and various tissues had a total of 23–24 FA components. The major FA components consisted of saturated (palmitic and stearic) at 22–34%, monosaturated (oleic) at 7–34% and polyunsaturated (eicosapentaenoic and arachidonic) FAs at 9–27%. According to principal component analysis, the FA signatures of juvenile haemolymph were greatly influenced by the shift of food sources from brine shrimp to clam and shrimp meat, whereas the FA profiles of different tissues were more resistant to the nutrient alteration. The present findings confirmed that the FA profile of both juvenile haemolymph and different tissues reflected the FA composition of recent and previous diets, respectively; and thus may be useful in indicating the foraging information of juvenile horseshoe crabs in the field.

The coast of Brazil is an important low latitude nursery ground for humpback whales (Megaptera novaeangliae). The number of humpback whales in this region has increased and its population is reoccupying areas where it has been depleted during the whaling period. The goal of this study was to conduct land-based observations during 2014 and 2015 to characterize patterns of habitat use and relative abundance of humpback whales that migrate to one of these reoccupation areas: Serra Grande, Bahia state. The observed mean group size was 2.12 ± 0.96 individuals and did not vary through the reproductive season nor between years. Dyads (32.9%) and singletons (26.7%) were more frequently observed, and groups with calves represented 21.2% of the sightings. The mean number of whales counted per hour increased from 2014 (3.44 ± 3.35) to 2015 (5.12 ± 4.18). Habitat use varied during the season; whales used shallower waters closer to shore as the season progressed. The spatial distribution of groups with calves was dependent on the presence and number of escorts. Spatial segregation of groups with calves closer to shore is a key factor in understanding the overall distribution of whales in the area, suggesting that social strategies are affected by environmental factors, as seen in other wintering grounds. Small-scale studies from land-based stations, in areas such as this where there is no previous knowledge about the species, are cost effective. They provide information about the overall behavioural and spatial patterns while anthropogenic activity is still low, allowing habitat protection and management decisions before implementation and increase of human activities.