Rafaela Barros Paiva

Discriminating bluemouth, Helicolenus dactylopterus (Pisces: Sebastidae), stocks in Portuguese waters by means of otolith shape analysis

ana neves, vera sequeira, ines farias, ana rita vieira, rafaela paiva and leonel serrano gordo Faculdade de Ciencias da Universidade de Lisboa, Departamento de Biologia Animal & Centro de Oceanografia, Bloco C2, Campo Grande, 1749-016 Lisboa, Portugal, Unidade de Recursos Marinhos e Sustentabilidade, Instituto de Investigacao das Pescas e do Mar (IPIMAR–INRB), Avenida Brasilia, 1449–006 Lisboa, Portugal

The gelatinous matrix of the teleost Helicolenus dactylopterus dactylopterus (Delaroche, 1809) in the context of its reproductive strategy

Abstract The bluemouth, Helicolenus dactylopterus dactylopterus (Pisces: Sebastidae), is a zygoparous species with internal fertilization that stores the spermatozoa in crypts within the female ovaries. It spawns gelatinous egg masses that were investigated in this study. Histological analysis confirmed that the ovarian wall and peduncular epithelia play an important role in the production of this gelatinous matrix that contained both oocytes and embryos. Cleavage and blastulae were the most frequent embryonic development stages observed and the tail bud was the latest stage reached. The chemical composition of the matrix was also investigated, revealing that water and proteins are the major components of this substance. This is the first study exclusively dedicated to the investigation of the composition, function and importance of the gelatinous matrix of H. d. dactylopterus in the context of its reproductive strategy.

Reproductive strategy of the female deep-water shark birdbeak dogfish, Deania calcea : lecithotrophy or matrotrophy?

Little information is available on the maternal–embryonic relationships among sharks. Birdbeak dogfish ( Deania calcea ) has been described as ovoviviparous, but this term comprises a wide range of forms on how the embryos are nourished including lecithotrophy and matrotrophy. To evaluate the maternal–embryonic relationship in birdbeak dogfish we have analysed chemical features (fatty acid composition and mercury (Hg) levels) and biological characteristics (egg and embryo dry weight variation, uterus characterization). Monounsaturated fatty acids were the dominant fatty acids in eggs while polyunsaturated fatty acids (PUFA) were the dominant fatty acids in both pregnant females and embryos. Significant differences were found among eggs, embryos and pregnant females for all fatty acids groups with the exception of saturated fatty acids for embryos and pregnant females. The principal components analysis revealed that embryos are particularly related to n-6 PUFA and pregnant females with n-3 PUFA. A close relationship exists between the Hg level of pregnant females and the Hg level of their embryos which indicates that there is a transfer of mercury from maternal sources. The comparison of the mean dry weight between eggs and embryos showed a gain of 3.8% obtained in the embryos. Histological sections of the uteri of pregnant females showed a high level of both superficial and inner vascularization in the uterine villi as well as the presence of secretor cells. Until now, the importance of this species maternal contribution and interference for the embryos development has never been documented. However, the biological and chemical results observed in the present work show that there is a matrotrophic strategy for the birdbeak dogfish.

Feeding habits of the cuttlefish Sepia officinalis during its life cycle in the Sado estuary (Portugal)

The importance of cephalopods in marine ecosystems is well recognized as they serve as important predators and prey in many food chains. During a 1-year period, cuttlefish were monthly sampled in five areas throughout the Sado estuary, and the stomachs of 445 individuals were examined. Significant changes in the diet according to their life stage were revealed, but similar food habits were presented by males and females. Juvenile individuals (the smaller ones with no visible distinct gonads) preyed mainly upon small crustaceans, while the immature ones (maturity stages I and II) had the most diverse diet with brachyurans as the major prey group. The mature individuals (maturity stages III and IV) showed a clear preference for larger crabs and fishes. Although the cuttlefish are known for their opportunistic feeding behaviour, a preference for some prey according to length and behaviour could be perceived during this study. Seasonal differences in the diet were mostly due to the variation of individuals according to their maturity stage during the year.

Diversity of sexual strategies of fish species caught by bottom trawl off the western Iberian Peninsula

Abstract Samples of boarfish Capros aper, small red scorpionfish Scorpaena notata and comber Serranus cabrilla were collected from monthly by-catch samples on board commercial trawlers off the western coast of Portugal. A histological approach was undertaken to study each species’ reproductive strategy and annual sexual cycle. Temporal variations of the gonadosomatic index and of two condition indices (hepatosomatic and Fultons K) were also analysed. Results showed that C. aper and S. notata are gonochoristic whilst S. cabrilla is a simultaneous hermaphrodite. Fertilization is external and development of secondary growth follicles is asynchronous in the three species. Mass atresia characterized the end of the spawning season in S. notata and S. cabrilla. In C. aper a high prevalence of atresia was observed throughout the year and was not attributed to regressing or regenerating phases or skip spawning events. The main spawning season of the three species was in the summer and it is suggested that spawning is related to upwelling. During the summer, the spawning interval was 1.09, 1.23 and 1.84 days for S. cabrilla, S. notata and C.aper, respectively. The results of this study indicate potential plasticity and environmental adaptation of sexual strategies.

Genetic and Morphological Variation of the Forkbeard, Phycis phycis (Pisces, Phycidae): Evidence of Panmixia and Recent Population Expansion along Its Distribution Area

The knowledge of population structure of a species is essential to effectively assess and manage fisheries. In the present study, genetics, by mitochondrial DNA cytochrome b sequence analysis, and body geometric morphometrics were used to evaluate the existence of distinct populations of the forkbeard (Phycis phycis), an important commercial species in several European countries, especially Portugal and Spain. For geometric morphometric analysis, specimens were collected in the Northeast Atlantic Ocean—Azores, Madeira and mainland Portugal, and for genetic analysis, these samples were complemented with samples collected in the Mediterranean Sea—Spain, Italy and Croatia, in order to cover the entire distribution area of the species. Body shape of the forkbeard from the Northeast Atlantic was found to be highly variable. This variation was probably associated with different environmental factors between the study areas. Despite morphological variation, a low genetic differentiation between samples from different areas was found, most likely due to gene flow that occurred in the past or with the demographic history of the species. Moreover, the presence of unique haplotypes in the Northeast Atlantic and in the Mediterranean suggests that recent gene flow between populations from these areas should be limited. Altogether, a high haplotype diversity, a low nucleotide diversity, a “star-like” network and the results of the mismatch distribution, indicate a possible signature of recent population expansions, which probably started during the end of the Last Glacial Maximum and led to the colonization of the Northeast Atlantic and the Mediterranean.

Age, growth and mortality of the comber Serranus cabrilla (Linnaeus, 1758) in the Eastern Atlantic

ABSTRACT Comber is an important bycatch species in the trawl fishery both in the Mediterranean and the Atlantic. Age and growth studies have been restricted to the eastern Mediterranean and no methodologies were ever applied to ensure accuracy and precision. In this study a total of 471 otoliths from specimens ranging from 12 to 26 cm were used. Precision indices showed a high level of agreement between readers and no evidence of systematic disagreement was obtained. To estimate fish growth and due to the absence of individuals smaller than 12 cm, three approaches were used to estimate the von Bertalanffy growth parameters: whole otolith readings, back calculation and a combination of both methodologies. Akaike’s information criterion suggests that the back calculation approach was the best one for describing comber growth: TL = 25.26 [1−e(−0.21(t+1.72)]. Natural mortality estimates varied between M = 0.44 year−1 and M = 0.48 year−1 while estimates of the fishing mortality varied between 0.12 year−1 and 0.16 year−1 and the exploitation rate between 0.20 and 0.27.

Zygoparity and sex steroid hormone profiles in bluemouth Helicolenus dactylopterus

Two hundred and seven individuals (103 females and 104 males) of bluemouth Helicolenus dactylopterus (Scorpaeniformes, Sebastidae), a commercially important deep-water species with an unusual reproductive strategy, from the eastern Atlantic Ocean ranging from 13·9 to 37·5 cm total length (LT ) were analysed from September 2011 to October 2012. The analysis included gonad maturity phases and blood-plasma levels of oestradiol-17β (E2 ), 11-ketotestosterone (11-KT) and 17,20β-dihydroxypregn-4-en-3-one (17,20β-P). Results confirmed the existence of an annual reproductive cycle with asynchrony between females and males and a spawning season from January to May. A pronounced peak in 17,20β-P in October for both sexes was associated with possible mating behaviour and recent copula. Levels of E2 increased preceding the elevation of the gonado-somatic index during ovarian growth and were lower during regression and regeneration. The frequency distribution of oocyte-embryonic stages and variation of hormone levels suggest the existence of daily rhythms. Fertilization was detected between 2000-0000 and 0800-1200 h and spawning took place throughout the day peaking between 2000 and 0000 h. The cyclic pattern of sex steroids and ovarian recruitment provides a new insight into the reproductive strategy of this species.

Age and growth of small red scorpionfish, Scorpaena notata (Actinopterygii: Scorpaeniformes: Scorpaenidae), a common discard species from the Portuguese fishery

Marine fisheries stock assessment plays an essential role in ensuring the sustainability of marine resources. Several species, which are not targeted by the fishery, are also caught as bycatch. The role that these fish species may play as prey, competitors, predators, and herbivores make them potential key members of communities and key determinants on how other populations fare (Foster and Vicent 2010). Bycatch species are typically not the focus of stock assessment efforts because of their limited economic importance, but they may suffer the same population declines as species with which they co-occur (Gertseva and Cope 2011) and life history knowledge of these species is also fundamental to manage their sustainability. Information on the age of individual fish species significantly enhances the quality of studies on population characteristics such as growth, recruitment, mortality, and reproduction, and it is often a prerequisite for more detailed studies on life history strategies and stock assessment (Labropoulou and Papaconstantinou 2000, Cailliet et al. 2001, Stewart and Hughes 2007). The majority of the studies on age and growth of fish involve the determination of age of specimens by counting of growth increACTA ICHTHYOLOGICA ET PISCATORIA (2015) 45 (1): 13–20 DOI: 10.3750/AIP2015.45.1.02

Risks and benefits' consumption of birdbeak dogfish Deania calcea

Purpose – There are very few studies that characterize the properties of the edible part from deep‐water fish species which constitute a new target for developing fisheries. Therefore this paper aimed to examine the balance between health benefits and risks associated to the birdbeak dogfish consumption, with a special emphasis on the assessment of the risks of toxic metal intake.Design/methodology/approach – Between September 2008 and May 2009, 82 individuals were analysed. The chemical composition (moisture, ash, protein and lipid content), essential elements (zinc (Zn), copper (Cu), iron (Fe), potassium (K), magnesium (Mg) and sodium (Na)), toxic elements (mercury (Hg), cadmium (Cd) and lead (Pb)) and fatty acid composition were determined using standard procedures.Findings – The species is a lean fish (fat content Na>Mg>Fe>Zn>Cu. The edible part of birdbeak dogfish is a good source of several minerals, na...