Ivone Figueiredo

Molecular barcoding of north-east Atlantic deep-water sharks: species identification and application to fisheries management and conservation

Two genera of elasmobranchii, Centrophorus and Centroscymnus, include species that represent the highest landings of deep-water sharks caught by fishing fleets operating in the north-east Atlantic. There are morphology-based identification problems among and within genera, and landings of processed shark products further prevent an objective assessment of these species. The present study is the first attempt to test the suitability of using a DNA barcode approach to discriminate accurately among the four most important commercial deep-water shark species: Centrophorus squamosus, Centrophorus granulosus, Centroscymnus coelolepis and, recently discovered in Portuguese ports, Centroscymnus owstoni. Sequence analyses of the mitochondrial DNA cytochrome c oxidase subunit I (COI) gene revealed low levels of haplotypic and genetic diversities. Higher levels of inter-specific relative to intra-specific divergences allowed discrimination among species, which form reciprocally monophyletic clades. Inclusion of published COI sequences from other species within the same genera revealed haplotype sharing among species, which calls into question the current taxonomy and accuracy of fisheries data available. Amplification of the COI gene coupled with MboI restriction digests was found to be a fast and inexpensive strategy to resolve within genera identification problems. Molecular barcoding constitutes a critical tool for the assessment and implementation of urgent management policies for this group of species.

Reproductive biology and embryonic development of Centroscymnus coelolepis in Portuguese mainland waters

A total of 871 females (76-122 cm) and 86 males (68-100 cm) of Centroscymnus coelolepis caught in Portuguese mainland waters were examined for reproductive characteristics. One hermaphroditic individual of 95 cm was found. Males were few in numbers and dominated by immature specimens. Female length at first sexual maturity was 98.5 cm. Mean ovarian and uterine fecundity were 13.2 oocytes per female and 9.9 embryos per pregnant female, respectively. Total length of embryos with completely absorbed external yolk sacs ranged between 233 and 300 mm. Sex ratio (F/M) of embryos with completely absorbed external yolk sac was 0.9. All stages of reproduction were found during the 12-month sampling period. Results were compared with those from other regions. A hypothesis is formulated on the existence of several regional populations based on morphometric and reproductive parameters observed in different areas.

Observations on the reproductive cycle of the black scabbardfish ( Aphanopus carbo Lowe, 1839) in the NE Atlantic

Black scabbardfish is a deep-water species, common in the NE Atlantic at depths between 450 and 1300 m, currently exploited by some European countries. Between May 1998 and April 2000, specimens collected at three different locations in the NE Atlantic—NW of Scotland, Sesimbra (mainland Portugal) and Funchal (Madeira)—were analysed. The evolution of maturity of both sexes throughout the year was studied based on the macroscopic and microscopic analysis of the gonads. Specimens with the largest total length were found in Funchal, whereas the smallest size was recorded in the NW of Scotland. Neither spawners nor post-spawners were ever observed in NW of Scotland and Sesimbra. In Sesimbra, only a few individuals attained pre-spawning stage and most of the early developing females exhibited atresia in their ovaries. In Funchal, all the maturity stages were found; spawners occurred from September to December (females) and from August to December (males). Length of first maturity for females was estimated to be around 1000 mm. Two groups of spawners with different sizes were observed during the spawning period off Madeira.

Molecular barcoding of skates (Chondrichthyes: Rajidae) from the southern Northeast Atlantic

Serra‐Pereira, B., Moura, T., Griffiths, A. M., Gordo, L. S. & Figueiredo, I. (2010). Molecular barcoding of skates (Chondrichthyes: Rajidae) from the southern Northeast Atlantic. —Zoologica Scripta, 40, 76–84.

The use of caudal thorns for ageing Raja undulata from the Portuguese continental shelf, with comments on its reproductive cycle

The present study focuses on age estimation, with reproductive information contributing to the better understanding of the growth and the biology of Raja undulata. In the age and growth study, two calcified structures were used: caudal thorns and central vertebra. Results of readings showed that there were no significant differences in age estimates between the two structures. Both von Bertalanffy and Gompertz growth models were fitted to size-at-age data by sex and geographical area. No significant differences were found between sexes for the two models but significant differences were found between geographical areas (P = 0.05). The Gompertz growth function was selected as the best model to describe R. undulata growth because it presented the best fit and the most reasonable biological estimates. Reproductive analysis indicates one annual breeding season for R. undulata. The differences found in the estimates of length at first maturity between geographical areas (TL50% = 838 mm in Peniche and 762 mm in Algarve for females and TL50% = 781 mm in Peniche and 736 mm in Algarve for males), together with the regional differences found between growth parameters estimates (P = 0.05), may reflect the existence of different local populations of R. undulata on the Portuguese continental shelf.

Strengths and Weaknesses of the Management and Monitoring of Deep-Water Stocks, Fisheries, and Ecosystems in Various Areas of the World—A Roadmap Toward Sustainable Deep-Water Fisheries in the Northeast Atlantic?

Scientific interest in deep-water marine resources has increased dramatically over the last 10–20 years as management bodies have sought advice on how to manage deep-water fisheries and protect deep-water ecosystems. The strengths and weaknesses of the management and monitoring of deep-water stocks, fisheries, and ecosystems in various areas of the world are described, with the objective of informing the EU FP7 DEEPFISHMAN project so that it can fulfill its primary aim, which is to develop strategic options for a short- and long-term management and monitoring ecosystem-based framework for the northeast Atlantic. To provide a baseline, the current monitoring and management regime in the northeast Atlantic is reviewed, followed by a brief description of the regimes applying to deep-water fisheries in the northwest Atlantic, the southeast Atlantic, off Brazil, in the Antarctic, off Australia and New Zealand, and in the Mediterranean. The strengths and weaknesses of these are discussed, taking into account additional information available from DEEPFISHMAN case study stocks, outcomes from consultations with stakeholders in the deep-water fishing industry in the northeast Atlantic, and the requirements of EU regulations and developing policy that will likely impact deep-water fisheries in the northeast Atlantic.

A technique for ageing the birdbeak dogfish (Deania calcea Lowe, 1839) from dorsal spines

Birdbeak dogfish (Deania calcea) is a squaloid shark captured along the Portuguese continental slope at depths between 400 and 900 m. Growth studies on this species based on the analysis of different calcified structures began in 1996 at the Portuguese Marine Research Institute (IPIMAR). The results obtained using the second dorsal spine as ageing material are a good basis for the future use of this structure for age determination. The technique developed for enhancing growth bands on the second dorsal spine of the birdbeak dogfish, which includes decalcification and staining of fine transversal spine sections, is described. By applying this technique to several specimens a clear growth pattern became evident on the sections analysed.

The development of the oviducal gland in the Rajid thornback ray, Raja clavata

The reproductive processes of chondrichthyans are complex. Knowledge of the development and maturation of the oviducal gland is vital for understanding the reproductive biology of a species. This study represents the first contribution of this subject for skates. In the oviparous thornback ray, Raja clavata, oviducal gland development begins early in the developing stage with the formation of gland tubules and the distinct lamellae of each zone: club, papillary, baffle and terminal. Oviducal development is complete by the end of the developing stage when the storage and secretion of products is evident within the gland tubules of each zone. Periodic acid-Schiff and alcian blue histological staining showed that the secretory mucous cells of the club and papillary zones produce neutral and sulfated acid mucins. The last row of gland tubules of the papillary zone stains intensely for sulfated acid mucins. The baffle zone, which is responsible for the production of the egg capsule, represented 60–80% of the glandular zone of the oviducal gland. Sperm bundles were observed in the deeper recesses of the baffle zone during the maturation process, and during capsule extrusion, sperm were detected near the lumen. The terminal zone was composed of two types of gland tubules: serous (producing protein fibres) and mucous glands (producing sulfated acid mucins).

Maturation of the Gonads and Reproductive Tracts of the Thornback Ray Raja clavata, with Comments on the Development of a Standardized Reproductive Terminology for Oviparous Elasmobranchs

Abstract There is a need for a unified terminology to describe reproductive phase assignment across fish taxa, regardless of the reproductive strategy involved. Reproductive terminology already adopted for teleosts has been applied to oviparous elasmobranchs of both sexes. A historical review of the terminologies used by previous authors and how these correspond to the new terminology is presented. Five reproductive phases are considered: immature, developing, spawning capable (which includes an actively spawning subphase), regressing, and regenerating. By using an oviparous elasmobranch, the thornback ray Raja clavata, as an example, the different phases are described based on both macroscopic and microscopic features of the reproductive tract, including the ovaries, oviducal glands, and uterus in females and the testes, claspers, and sperm ducts in males. The regressing phase was observed in females, but the regenerating phase was not; neither of these two phases was observed in males. Records from other species suggest that all five reproductive phases can be found in oviparous elasmobranchs, depending on the reproductive strategy of the species.

Feeding habits of Chimaera monstrosa L. (Chimaeridae) in relation to its ontogenetic development on the southern Portuguese continental slope

At the Portuguese continental slope, rabbitfish, Chimaera monstrosa, is distributed at depths greater than 200 m. The feeding strategy of this species was investigated based on the analysis of digestive tract contents from specimens captured during a bottom trawl survey held along the southern continental slope of Portugal. The diet of rabbitfish is high in diversity and with differences in composition according to predator size groups. Specimens smaller than 22 cm (pre-supracaudal fin length), which occurred in a restricted area, mainly fed on amphipods, while those with lengths between 22 and 46 cm fed on amphipods and decapods. Larger individuals (>46 cm) had a narrow diet spectrum, consuming mainly decapods. Conditioned by predator size group, significant differences in diet were observed between geographical areas and depths. This suggests that despite some degree of prey specialization according to predator size, this deep-water species is able to change its diet in accordance with the food-restricted environment that characterizes its habitat.