Phylogenetic prospecting for cryptic species of the genus Merluccius (Actinopterygii: Merlucciidae).

Hakes of the genus Merluccius include 11 valid species as well a number of rare morphotypes suspected to be "cryptic species". Concatenated nucDNA ITS1-rDNA and mtDNA cyt b sequences plus nested ITS1Nes sequences allowed to ascribe 14 specimens of nine rare morphotypes from the South Pacific and the South Atlantic to the phylogenetic backbone of this genus. Bayesian analyses pointed to M. bilinearis and M. albidus as the oldest species of the genus and the New World cluster, respectively. The phylogenetic status of M. angustimanus from the upper Gulf of California suggests its hybrid origin between M. gayi and M. productus from about 0.25 MYA, although an ever since confinement of a subset of those species cannot be ruled out. The molecular phylodiagnostic test suggests a common origin of all rare morphotypes and the absence of cryptic hake species in the Southern Cone. The molecular background of the morphotypes distributed between the Western Pacific South of New Zealand and the western Atlantic South of Argentina is compatible with their hybrid origin between M. gayi and both, M. australis or M. hubbsi, respectively.

Morphological and biochemical approaches to assess the nutritional condition of the Argentine hake Merluccius hubbsi larvae from two different nursery areas.

The Argentine hake, Merluccius hubbsi, is one of the most important fishing species in the Argentine Sea due to its great abundance and high-quality meat. The study of the nutritional condition is widely used to determine the physiological state of the fish larvae and to estimate their survival possibilities. The larval nutritional condition reflects the environmental conditions to which they have been exposed and represents a useful instrument to determine favourable nursery areas. It also provides tools for the comprehensive management of a population subjected to fishing exploitation. This study aimed to determine potential differences in the nutritional condition of M. hubbsi larvae from the two fishing stocks (Northern and Southern) of the species. The authors assessed the nutritional condition of larvae captured during the 2012 main reproductive peak in the nursery areas of each population. Two different methodologies were applied: a morphometrical approach, by recording five morphometric variables, and a biochemical technique, employing the RNA/DNA index (RDs ) and its derived index of growth performance. The morphometrical indexes did not show differences in the larval condition between both stocks. Nonetheless, the RDs index did detect differences in the nutritional condition of larvae from different stocks. The RDs index of larvae in pre-flexion and flexion stages showed significant differences between stocks, indicating that these stages are more susceptible to starvation. The results suggest that the biochemical indexes prove to be more sensitive than the morphometric indexes to detect slight differences in hake larvae nutritional condition. The scope and limitations of these techniques for the analysis of the nutritional condition of larvae are discussed.

Morphological studies on the gills of the European hake (Merluccius merluccius, Linnaeus, 1758).

The current work gives concern to study the morphology of the Merluccius merluccius gills by using gross morphology, scanning electron microscopy (SEM), and light microscopy. The findings of the present study revealed that the gill system consisted of four pairs of gill arches which carry the gill filaments on the convex border and gill rakers on the concave border of them. SEM results revealed that the rakers and the spines distribution on the first gill arch differed from that of the other three gill arches on the lateral and medial surfaces. On the surface the gill filaments, there were longitudinal ridges that carried pores of chloride cells and mucous cells. The histological examination revealed that, the gill arch composed of hyaline cartilage that presented in the form of cups. Each cup consisted of central cartilagenous core and peripheral cartilagenous matrix. The gill filaments composed of cartilaginous bar of peripheral cartilaginous matrix and central cartilaginous core extended from the gill arches and covered by an epithelial layers with a few mucous cells permeate it, and chloride cells were straggly in the interlamellar epithelium. Each gill filament carried several leaves like secondary lamellae on both sides of it. The epithelium, which lined the secondary lamellae, composed of epithelial pavement cells, some mucous cells, and pillar cells.

Vertebral column deformity in adult wild haddock (Melanogrammus aeglefinus).

This study describes radiological malformations in the vertebral column of adult sexually mature wild haddock, Melanogrammus aeglefinus collected from Masfjorden, Western Norway, in 2014 and 2015. There were seven deformed fish (33% of sampled fish), five with mild deformities and two with severe deformities. The deformity types discovered were lordosis, vertebra body asymmetry, compression, fusion (ankylosis), remodelling, and haemal spine hyperostosis. The two severely deformed fish were as follows: (a) one specimen with 29 deformed vertebrae within the region vertebrae nos. 1-30, including two sites of lordosis; (b) one specimen with 15 deformed vertebrae within the region vertebrae nos. 31-52 (most caudal vertebrae). The results of this study show that wild haddock can survive severe vertebra deformities, both in the trunk and tail region, and reach adulthood and sexual maturity. Whether normal nondeformed wild conspecifics would mate and spawn with these individuals and thereby complete the life cycle of the deformed individuals is, however, unknown. A possible link between bone fracture and fish hyperostosis is discussed.

Unravelling growth trajectories from complicated otoliths - the case of Brazilian codling Urophycis brasiliensis.

Uncertainty regarding the age determination of the Brazilian codling Urophycis brasiliensis has hampered its stock assessment. Transverse sections of otoliths displayed up to seven (in males) and 12 (in females) alternate opaque and translucent bands that could not be conclusively validated as annuli, resulting in unrealistically high ages of first maturity (A50 ) (A50male = 4·5 years and A50female = 6 years). Therefore, growth was described by the von Bertalanffy (VB) model using an alternative approach that combined microstructure data (daily growth increments) and a fixed asymptotic total length (L∞ ). This approach was supported by applying it to two other co-occurring species, the whitemouth croaker Micropogonias furnieri and the king weakfish Macrodon atricauda, for which daily and annual ring formation has previously been validated. The sensitivity to realistic errors associated with the choice of the L∞ and the daily increment readings was shown to be low. The results show that U. brasiliensis has a fast growth rate (Kmale = 1·19 year-1 , Kfemale = 0·71 year-1 ) and early maturation (A50male = 1·1-1·5 years, A50female  = 1·6-1·8 years); typical life-history traits for a sub-tropical coastal gadiform. This novel study offers an alternative approach for age and growth reconstruction for species with complex patterns of opaque and translucent bands provided that daily growth increments in the yearlings can be counted and L∞ reliably estimated.

Otolith shape variability and associated body growth differences in giant grenadier, Albatrossia pectoralis.

Fish stocks can be defined by differences in their distribution, life history, and genetics. Managing fish based on stock structure is integral to successful management of a species because fishing may affect stocks disproportionately. Genetic and environmental differences can affect the shape and growth of otoliths and these differences may be indicative of stock structure. To investigate the potential for speciation or stock structure in giant grenadier, Albatrossia pectoralis, we quantified the shape of female giant grenadier otoliths and compared body growth rates for fish with three otolith shapes; shape types were classified visually by an experienced giant grenadier age reader, and were not defined by known distribution or life history differences. We found extreme variation in otolith shape among individuals; however, the shapes were a gradation and not clearly defined into three groups. The two more extreme shapes, visually defined as "hatchet" and "comb", were discernable based on principal component analyses of elliptical Fourier descriptors, and the "mixed" shape overlapped both of the extreme shapes. Fish with hatchet-shaped otoliths grew faster than fish with comb-shaped otoliths. A genetic test (cytochrome c oxidase 1 used by the Fish Barcode of Life Initiative) showed almost no variability among samples, indicating that the samples were all from one species. The lack of young specimens makes it difficult to link otolith shape and growth difference to life history. In addition, shape could not be correlated with adult movement patterns because giant grenadiers experience 100% mortality after capture and, therefore, cannot be tagged and released. Despite these limitations, the link between body growth and otolith shape indicates measurable differences that deserve more study.

Timecourse of oocyte development in saithe Pollachius virens.

Wild caught North Sea saithe Pollachius virens were monitored for growth, sex steroid profiles and oocyte development pre-spawning and measured for egg size and group fecundity during the spawning season in the laboratory. Vitellogenesis commenced in late October-early November, at a leading cohort size (CL ) of c. 250 µm, after which oocytes grew rapidly in size until spawning started in February. Notably, a distinct cortical alveoli stage was virtually absent with yolk granules observed in developing oocytes at the very beginning of vitellogenesis. Little atresia was observed pre-spawning, but atretic re-absorption of remnant oocytes containing yolk granules was found in all females immediately post-spawning. As expected, concentrations of sex steroids, oestradiol-17ß (females), testosterone (both sexes) and 11-ketotestosterone (both sexes), increased pre-spawning before dropping post-spawning. The present experiment provides the first validation of sex steroid levels in P. virens. Post-ovulatory follicles were visible in histological sections from female gonads 9-11 months post-spawning, but then disappeared. Spawning commenced around a CL of c. 750 µm (700-800 µm). Hydrated oocytes (eggs) measured between 1·04 and 1·31 mm (mean = 1·18 mm) with decreasing sizes towards the end of spawning. The average estimated realized fecundity was c. 0·84 million eggs (median female total length, LT = 60 cm). Spawning lasted from 13 February to 29 March.

Induction of gonadal maturation at different temperatures in burbot Lota lota.

A rearing experiment was conducted to test whether temperature protocols that differed from a simulation of natural conditions might induce maturation after isothermal grow-out in burbot Lota lota. Lota lota were acclimated to two different temperature regimes: low temperature (LT), close to natural temperature at 4·0° C and elevated, high temperature (HT) at 8·5° C over 40 and 27 days respectively, with all fish then wintered for 47 days. Every second fish was treated with a gonadotropin-releasing hormone analogue. Maturational competence of oocytes was assessed with a germinal vesicle breakdown assay using a novel staining strategy. In both treatments, puberty and maturational progress occurred, characterised by an elevated gonado-somatic index and advanced gonadal stages (histological analysis). Progress of gonadal maturation was reflected by elevated plasma concentrations of testosterone and 11-ketosterone in males and 17ß-oestradiol in females. Ovulation was not observed. Sperm could be activated equally across treatments. In general, LT was more effective than HT treatment, indicated by advanced gonadal stages, higher numbers of oocytes undergoing germinal vesicle breakdown in vitro and elevated sex steroid levels. Hormone treatment could improve effectiveness at HT. In conclusion, less drastic temperature regimes as previously reported in combination with hormone treatments seem sufficient to induce maturation in L. lota after isothermal grow-out.

Redescription of Urophycis brasiliensis (Kaup 1858), a senior synonym of Urophycis latus Miranda Ribeiro 1903 (Gadiformes: Phycidae).

Urophycis Gill 1864 is a genus of demersal fish composed by eight valid species with anti-tropical distributions in the western Atlantic. Only two species occur in the South Atlantic: U. brasiliensis (Kaup 1858) and U. mystacea Miranda Ribeiro 1903. These species have similar ranges from southeastern Brazil to northern Argentina, but U. brasiliensis occurs in more shallow waters than U. mystacea. Both species are important fishery resources in southern Brazil and Uruguay. Herein, we redescribe U. brasiliensis based on comparison of types and additional specimens, including the description of the Sagitta otolith, formerly place U. latus Miranda Ribeiro 1903 as a junior synonym of U. brasiliensis, and provide an updated map of distribution.

New records of larval stages of the eel cod genus Muraenolepis Günther 1880 (Gadiformes: Muraenolepididae) from the western Antarctic Peninsula.

Three newly discovered larval specimens of the genus Muraenolepis collected from the waters of the western Antarctic Peninsula are described. Knowledge of their natural history is sparse and information about their early life history is based on only a few larval stages. Here, the available literature on larval eel cods is reviewed, and the specimens placed in context.

Levels of infection and seasonal occurrence of Gyrodactylus alviga (Monogenea: Gyrodactylidae) on the whiting Merlangius merlangus off the Turkish and Russian coasts of the Black Sea.

Gyrodactylus alviga is a generalist species reported in many Black Sea fish species, but whiting is known to be its main host. It is the only monogenean parasite that has been reported so far on the skin, fins and gills of whiting Merlangius merlangus in the Black Sea. A total of 690 fish from Turkey and 423 fish from Russia were examined to detect parasites. Infection indices of prevalence, mean intensity and mean abundance values were calculated for length classes and sex of fish, as well as for the seasons. There is a gradual increase in infection indices in relation with increasing host length classes and there are higher infection indices on female fish. Furthermore, despite lower prevalence indices in spring and winter, higher parasite intensity values were determined in these seasons. It is concluded that larger fish provided more space and food for G. alviga, and female fish were more parasitized as they were more active in searching for food, which enables the parasite to switch between hosts. In addition, winter and spring were more appropriate for reproduction of G. alviga.

Effects of density dependence, zooplankton and temperature on blue whiting Micromesistius poutassou growth.

Blue whiting Micromesistius poutassou mean total length at age in the north-east Atlantic Ocean was found to vary by around ±6% during the period 2004-2011 and mean mass at age by ±22% during the years 1981-2013. Linear modelling provided strong evidence that these phenotypic growth variations can be explained by trophic conditions, mainly negative density dependence and also food availability, and a negative long-term temperature effect on asymptotic size.

[IMPACT OF SIX COOKING TECHNIQUES ON FATTY ACID COMPOSITION OF MARLIN (MAKAIRA NIGRICANS) AND HAKE (MERLUCCIUS PRODUCTUS)]. / IMPACTO DE SEIS TÉCNICAS DE COCCIÓN SOBRE LA COMPOSICIÓN DE ÁCIDOS GRASOS EN MARLÍN (MAKAIRA NIGRICANS) Y MERLUZA (MERLUCCIUS PRODUCTUS).

INTRODUCTION: the regular consumption of fish brings benefits to health due to its content of n-3 fatty acids, but cooking enhances or damages the concentration of fatty acids (FA) since they are susceptible to oxidation by temperatures and cooking times. OBJECTIVES: to analyze the effect of six cooking techniques on total lipids (TL) and (FA) content in marlin and hake and select which one helps the best conservation of health beneficial FA. METHODS: fillets were subjected to different cooking techniques: steam (ST), foiled-aluminum-paper (FAP), foiled- banana-leaf (FBL), gas-oven (GO), microwave-oven (MO) and fried-lightly (FL). FA were identified by gas chromatography/FID. RESULTS AND DISCUSSION: Marlin: FL increased the concentration of TL and MO decreased it. Statistically, PUFA, SFA and EPA + DHA increased with FAP, MUFA decreased with FBL and increased in FL. Hake: FL increased concentration in all groups of FA while ST decreased it. SFA values and index of atherogenicity (IA), thrombogenicity (IT), peroxidisability and hipocolesterolemic/ hipercolesterolemic fatty acid ratio (HH) found, suggested that hake is a fish with greater health benefits, regardless of the technique you employ. By its EPA + DHA content, marlin seems to be an excellent choice if cooked FAP. FL technique in both species decreased the IA, IT and significantly increased the HH; however n3/n6 ratio decreased. ST seems to be the least desirable cooking technique for both species.

Introducción: el consumo frecuente de pescado aporta beneficios a la salud por su contenido en ácidos grasos n-3. Generalmente se consume cocinado pero la cocción mejora o perjudica la concentración de ácidos grasos(AG), pues son susceptibles a oxidarse por las temperaturas y tiempos de cocción. Objetivos: analizar el efecto de seis técnicas de cocción sobre los lípidos totales (LT) y AG de marlín y merluza y seleccionar la que favorece una mejor conservación de AG de importancia para la salud. Métodos: se sometieron los filetes a diferentes técnicas de cocción: vapor (VA), empapelado papel-aluminio (EA), empapelado hoja-plátano (EP), horno-gas (HG), horno-microondas (HM) y sofrito (SF). Los AG se identificaron por cromatografía de gases/FID. Resultados y discusión: Marlín: el SF aumentó la concentración de LT y el HM la disminuyó. Estadísticamente, los AGS, AGP y EPA + DHA aumentaron con EA, los AGM disminuyeron con EP y aumentaron en el SF. Merluza: el SF aumentó la concentración en todos los grupos de AG, mientras que el VA la disminuyó. Por los valores de AGS, índices de aterogenicidad (IA), trombogenicidad (IT), susceptibilidad a la peroxidación y relación hipocolesterolémica/ hipercolesterolémica de los ácidos grasos (HH) encontrados, se sugiere que la merluza es un pescado con mayores beneficios para la salud, independientemente de la técnica que se aplique. Por su contenido en EPA + DHA el marlín parece ser una excelente opción si se cocina en papel aluminio. La técnica de sofrito en ambas especies disminuyó el IA, IT y aumentó significativamente la HH, sin embargo la relación n3/n6 disminuyó. La técnica menos conveniente para ambas especies resultó ser el VA.

Merluccius tasmanicus Matallanas & Lloris 2006 is a junior synonym of M. australis (Hutton 1872) (Gadiformes: Merluciidae) based on morphological and molecular data.

The high intraspecific variation among and the conservative external morphology of Merluccius spp. have resulted in serious identification difficulties. Four hundred and twenty fresh and preserved specimens of Merluccius were analyzed, including the type series of Merluccius australis, M. tasmanicus and M. hubbsi; specimens of M. hubbsi from Argentina, Brazil and Uruguay, and individuals of M. australis from Argentina and New Zealand were examined. The nomenclatural status of the type specimens of M. australis is discussed and the designation of a lectotype and a paralectotype is proposed. The comparative study of morphology, meristic, traditional and landmark-based morphometry, both external and internal, and through DNA-based Barcoding molecular tools demonstrates that Merluccius tasmanicus is a junior synonym of Merluccius australis. Meristic and morphometric characters of types of M. tasmanicus completely overlap those of M. australis, whereas M. hubbsi show fewer scales along the lateral line, total vertebrae, second dorsal and anal-fin rays. A trend of a longer snout and wider head in M. australis and M. tasmanicus, and larger eyes and longer pelvic fins, in M. hubbsi was observed. While discriminant characters were found in the internal elements (hyomandibula, urohyal and sagitta otolith) between M. hubbsi and M. australis, none were observed between M. australis and those reported for M. tasmanicus. DNA barcoding analyses found no evidence of the existence of other species of Merluccius besides M. hubbsi and M. australis.

Material properties of Pacific hake, Humboldt squid, and two species of myctophids in the California Current.

Material properties of the flesh from three fish species (Merluccius productus, Symbolophorus californiensis, and Diaphus theta), and several body parts of the Humboldt squid (Dosidicus gigas) collected from the California Current ecosystem were measured. The density contrast relative to seawater varied within and among taxa for fish flesh (0.9919-1.036), squid soft body parts (mantle, arms, tentacle, braincase, eyes; 1.009-1.057), and squid hard body parts (beak and pen; 1.085-1.459). Effects of animal length and environmental conditions on nekton density contrast were investigated. The sound speed contrast relative to seawater varied within and among taxa for fish flesh (0.986-1.027) and Humboldt squid mantle and braincase (0.937-1.028). Material properties in this study are similar to values from previous studies on species with similar life histories. In general, the sound speed and density of soft body parts of fish and squid were 1%-3% and 1%-6%, respectively, greater than the surrounding seawater. Hard parts of the squid were significantly more dense (6%-46%) than seawater. The material properties reported here can be used to improve target strength estimates from acoustic scattering models, which could increase the accuracy of biomass estimates from acoustic surveys for these nekton.

Head and otolith morphology of the genera Hymenocephalus, Hymenogadus and Spicomacrurus (Macrouridae), with the description of three new species.

The fishes of the genus Hymenocephalus live over continental slope terrain, chiefly between 300 and 1000 m water depths, in all tropical oceans, except the eastern Pacific. They are characterized by an elongated light organ with two lenses, striations on jugular and thorax, and by an extraordinary development of sensory reception organs: strongly enlarged eyes, exceptionally large and specialized sagittal otoliths and extremely wide and deep head canals resembling caverns and housing the cephalic sensory organ for motion reception (lateral line system).        The purpose of this study is to evaluate the potential that a detailed analysis of the head and otolith morphology can offer for distinguishing the various species and assessment of their interrelationships. About 500 specimens were investigated, representing all 22 nominal species of the genus Hymenocephalus, except for H. barbatulus (specimens of which could not be located), the two species of the related genus Hymenogadus and three of the four species of Spicomacrurus.  Because of the delicate and thin nature of the head bones and head skin typical for the fishes of the genus Hymenocephalus and the deteriorating effects of formalin to the aragonitic otoliths, only a fraction of the studied specimens actually contributed useful data, although that fraction represented all species studied.        Otoliths in particular and aspects of the cephalic canal system were found to contribute additional characters that help to verify the status of certain controversial species such as H. heterolepis, H. nascens and species within the H. striatissimus and H. grimaldii Groups. Hymenocephalus longiceps is revised to represent a junior synonym of H. longibarbis. Eight species groups are defined within the genus Hymenocephalus. Three new species are being described in the course of this review: H. iwamotoi from off northwestern Australia, H. sazonovi from the Sala y Gomez and Nazca Ridges, and H. punt from northern Somalia and the Gulf of Aden, now raising the count of valid species in the genus to a total of 24.        The specializations of the sensory reception organs show a variety of developments with well-expressed phylogenetic polarities that are discussed in the context of their evolution and interrelationships. A well-documented case of polarity reversal of certain characters in the H. aterrimus Group is interpreted as a functional adaptation to migration of these fishes into a deeper water environment that favors different specializations of the sensory reception.

Descriptions of four species of grenadier fishes of the genera Hymenocephalus and Hymenogadus (Teleostei, Gadiformes, Macrouridae) from the New Zealand region and Tasman Sea, including two new species of Hymenocephalus.

Two new species of Hymenocephalus are described from the New Zealand region and Tasman Sea. Hymenocephalus fuscus sp. n. has 11-12 pelvic fin rays, is darkly pigmented, with enlarged bony ridges on the dorsal aspects of head, lacks a chin barbel, has few (16-19) gill rakers on inner side of first arch and is similar to other species in the H. aterrimus species group. Hymenocephalus maculicaudus sp. n. has 8 pelvic fin rays, a mid-lateral line of melanophores on body and tail that extends about a head length posterior to anal fin origin, a short (7-16 % HL) chin barbel and is similar to other species in the H. megalops species group. Hymenocephalus nascens has 12-14 pelvic fin rays, lacks a chin barbel, has a mid-lateral stripe of silvery (fresh) or brownish (preserved) pigment running along trunk and tail. Hymenogadus gracilis has a serrated (weak, near tip) first dorsal fin spine, 7-9 pelvic fin rays, long (20-30% HL) chin barbel, and one row of enlarged melanophores along lateral mid-line of the tail. Hymenocephalus nascens and Hymenogadus gracilis are recorded for the first time from the New Zealand region. A key to the known New Zealand species of Hymenocephalus and Hymenogadus is provided. 

Caracterización histológica y morfológica del tracto digestivo de la merluza austral (Merluccius australis) / Histological and morphological characterization of the digestive tract of southern hake (Merluccius australis)

Las características anatómicas e histológicas del tracto alimentario de la merluza austral (Merluccius australis) se han estudiado con el fin de comprender la fisiología digestiva y formular alimentos balanceados adecuados. M. australis posee un esófago corto, un estómago en forma de y grande y un intestino corto. Histológicamente, el tracto digestivo está formado por cuatro capas: la mucosa, submucosa, muscularis y la serosa. El esófago es un órgano tubular corto de pared gruesa con una gran capacidad de distensión y abundantes células caliciformes secretoras de mucus que permite el paso de grandes presas. El estómago es grande y musculoso, con alta capacidad de distensión. No se observo la presencia de apéndices pilóricos. El intestino es corto y dividido en regiones: proximal, medio y distal. En la región anterior del intestino se observaron abundantes células caliciformes, que disminuyeron en la región media para finalmente dispersarse en la región posterior. Además, los enterocitos mostraron un aumento en la presencia de vacuolas supranuclear en la región posterior del intestino. Los resultados de este estudio anatómico e histológico indican que M. australis tiene un sistema digestivo similar a otros peces gadiformes, el cual está adaptado para digerir y absorber presas ricas en proteínas, principalmente pescados y crustáceos.

The anatomy and histology features of alimentary tract of southern hake (Merluccius australis) have been studied in order to understand the digestive physiology and formulate suitable feeds. M. australis has a short oesophagus, large y-shaped stomach and short intestine, and histologically, the digestive tract is formed by four layers: mucosa, submucosa, muscularis and serosa. The oesophagus is a short tubular thick-walled organ with a great distension capacity and abundant mucus secreting goblet cells allowing the passage of large preys. The stomach is large and muscular with high capability for distension. Pyloric caeca were not present. The intestine is short and divided into a proximal middle and distal segment. In the anterior region of the intestine was observed abundant goblet cells, which decreased in the middle region and finally dispersed in the posterior region. Additionally, enterocytes showed an increase in the presence of supranuclear vacuoles at the posterior region of the intestine. The results of this anatomical and histological study indicate that M. australis has a digestive tract similar to other gadiform fishes, which is adapted to digest and absorb protein-rich preys, mainly fish and crustacean.

Captura de peces no comerciales con espinel experimental de fondo en Isla Gorgona, Colombia, y su área de influencia / Non-commercial fish catches with experimental bottom long line fishing in Gorgona Island, Colombia, and its surroundings areas

Eels and moray eels are among the species that lack commercial value but that are important as bait. However, little information is available about Colombian fishing by-products. Between 2005 and 2009, field work was done in Gorgona National Natural Park and its surrounding areas, with a fishing line made of traditional “J” and circular or curve hooks. We analyzed the catch composition, comparing both types of hooks, emphasizing whether the circular hook modified or not non-commercial captures. Overall, 189 fishing throws where analyzed, standardizing the Catch Per Effort (CPUE) in number of individuals and in kilograms per 100 hooks per hour of task. A total of 50 species where captured, of which 14 are part of the non-commercial category. There were no significant differences for hook types (U=25228, P>0.1), and Gymnothorax equatorialis and Echiophis brunneus were the most abundant species. Both were concentrated in the northern sector of the study area, a rocky banks sector. The mean sexual maturity size was 57.0cm in G. equatorialis, and at 85.6cm in E. brunneus. Rev. Biol. Trop. 62 (Suppl. 1): 391-405. Epub 2014 February 01.

Durante los años 2005 a 2009 se realizaron faenas experimentales de pesca en el Parque Nacional Natural Gorgona y su área de influencia, con un espinel compuesto por anzuelos tradicionales J y circulares o curvos. Este estudio analiza la composición de las capturas comparando los dos anzuelos y enfatiza en si el anzuelo circular modifica o no las capturas no comerciales (descarte). En total se analizaron 189 lances de pesca estandarizándose la captura por unidad de esfuerzo (CPUE) en número de individuos y en kilogramos por 100 anzuelos por hora de faena. Se capturaron en total 50 especies, de las cuales 14 hacen parte de la categoría no comercial o de descarte. No se detectaron diferencias significativas en la CPUE de estas especies considerando el tipo de anzuelo (U=25228, p>0.1) siendo Gymnothorax equatorialis y Echiophis brunneus las especies más abundantes Al evaluar el patrón espacial de variación de la CPUE para estas especies, se encontró que ambas se concentran en el sector norte del área de estudio, asociada a la zona de bancos rocosos. Finalmente, se estableció la talla media de madurez sexual para G. equatorialis en 57.0cm y de E. brunneus en 85.6cm.

Taxonomic study of Bathygadidae fishes (Gadiformes) from Atlantic Spanish waters combining morphological and molecular approaches.

From 2009 to 2011 eleven specimens belonging to four bathygadid species of the family Bathygadidae were captured in two different locations in the northern waters of Spain. The morphometric measurements and meristic characters of these specimens are given. The specimens were identified as belonging to the genera Gadomus Regan, 1903, and Bathygadus Günther, 1878, including the following species: Gadomus dispar (Vaillant, 1888), Gadomus longifilis (Goode & Bean, 1885), Gadomus arcuatus (Goode & Bean, 1886) and Bathygadus melanobranchus Vaillant, 1888. As a result, a new northern limit of distribution of G. arcuatus from the northeastern Atlantic is reported. The first molecular identification and genetic interrelationships of Bathygadidae species, based on the mitochondrial COI nucleotide sequences -DNA barcodes- is reported. Sequences corresponding to specimens from the same species were identical and the overall mean genetic diversity (uncorrected p-distance) was 0.096 ± 0.008. Based on a morphological and meristic examination of the specimens, as well as on the available literature, an updated key of the members of the family Bathygadidae from the north-eastern Atlantic Ocean is provided.