Near-surface captures of post-juvenile anglerfish in the North-east Atlantic—an unsolved mystery

Thirty four well-grown (length range 24–103 cm) individuals of the demersal anglerfish Lophius piscatorius were captured close to the surface at widely scattered locations in the North-east Atlantic, some over considerable depths (to 2600 m).     

A new set of highly polymorphic microsatellites for the white and black anglerfish (Lophiidae)

A microsatellite‐enriched genomic library was obtained using individuals of the black anglerfish (Lophius budegassa) and eight polymorphic microsatellites were successfully optimized. The genetic analysis of 50 black anglerfish individuals captured in the Cantabrian coasts revealed high polymorphism with a mean of number of alleles per locus of N_a = 10.5 (5–28 alleles) and a mean expected heterozygosity of 0.740 (0.521–0.962). This microsatellite set was also functional with a sample from the white anglerfish (Lophius piscatorious) showing a high polymorphism.     

A note on the development of the embryos of anglerfish Lophius piscatorius

Embryo development over a 5 day period are shown and described from a rare find of anglerfish Lophius piscatorius spawn that was obtained at the Shetland Islands, U.K. The stage of development shown is earlier than that previously available for the species.     

New findings of <Emphasis Type="Italic">Lophius litulon</Emphasis> (Lophiidae) off the Southern Kurils

Data on new captures of juveniles of the yellow anglerfish Lophius litulon off the Southern Kurils are presented. Outer morphological characters of the specimens caught in waters off the Southern Kurils are described in comparison with those of specimens from other regions of the north-western part of the Pacific Ocean. Probable pathways of penetration of anglerfish (Lophiidae) to Russian Far East waters are discussed.     

Localization and characterization of neuropeptide Y-like peptides in the brain and islet organ of the anglerfish (Lophius americanus)

Summary Results from a previous report demonstrate that more than one molecular form of neuropeptide Y-like peptide may be present in the islet organ of the anglerfish (Lophius americanus). Most of the neuropeptide Y-like immunoreactive material was anglerfish peptide YG, which is expressed in a subset of islet cells, whereas an additional neuropeptide Y-like peptide(s) was localized in islet nerves. To learn more about the neuropeptide Y-like peptides in islet nerves, we have employed immunohistochemical and biochemical methods to compare peptides found in anglerfish islets and brain. Using antisera that selectively react with either mammalian forms of neuropeptide Y or with anglerfish peptide YG, subsets of neurons were found in the brain that labelled with only one or the other of the antisera. In separate sections, other neurons that were labelled with either antiserum exhibited similar morphologies. Peptides from brains and islets were subjected to gel filtration and reverse-phase high performance liquid chromatography. Radioimmunoassays employing either the neuropeptide Y or peptide YG antisera were used to examine chromatographic eluates. Immunoreactive peptides having retention times of human neuropeptide Y and porcine neuropeptide Y were identified in extracts of both brain and islets. This indicates that peptides structurally similar to both of these peptides from the neuropeptide Y-pancreatic polypeptide family are expressed in neurons of anglerfish brain and nerve fibers of anglerfish islets. The predominant form of neuropeptide Y-like peptide in islets was anglerfish peptide YG. Neuropeptide Y-immunoreactive peptides from islet extracts that had chromatographic retention times identical to human neuropeptide Y and porcine neuropeptide Y were present in much smaller quantities. These results are consistent with the hypothesis that peptides having significant sequence homology with human neuropeptide Y and porcine neuropeptide Y are present in the nerve fibers that permeate the islet.     

Distribution of peptidyl-glycine alpha-amidating monooxygenase immunoreactivity in the brain,pituitary and islet organ of the anglerfish (Lophius americanus)

Peptidyl-glycine alpha-amidating monooxygenase (PAM; EC 1.14.17.3) is an enzyme that catalyzes conversion of glycine-extended peptides to alpha-amidated bioactive peptides. Two peptides that are processed at their carboxyl-termini by this enzyme are neuropeptide Y and anglerfish peptide Y, both of which possess a C-terminal glycine that is used as a substrate for amidation. Results from previous reports have demonstrated that neuropeptide Y-like and anglerfish peptide Y-like immunoreactivities are present in the brain of anglerfish (Lophius americanus). Furthermore, neuropeptide Y-like peptides, namely anglerfish peptide Y and anglerfish peptide YG (the homologues of pancreatic polypeptide) are present in the islet organ of this species. Neuropeptide Y has also been localized in the anterior, intermediated and posterior lobes of the pituitary gland in a variety of species. In order to learn more about the distribution of the enzyme responsible for alpha amidation of these peptides in the brain and pituitary and to specifically investigate the relationship of this enzyme to peptide synthesizing endocrine cells of the anglerfish islet, we performed an immunohistochemical study using several antisera generated against different peptide sequences of the enzyme. PAM antisera labeled cells in the islet organ, pituitary and brain, and fibers in the brain and pituitary gland. The PAM staining pattern in the brain was remarkably similar to the distribution of neuropeptide Y immunoreactivity reported previously. Clusters of cells adjacent to vessels in the anterior pituitary displayed punctate PAM immunoreactivity while varicose fibers were observed in the pituitary stalk and neurohypophysis. Endocrine cells of the islet organ were differentially labeled with different PAM antisera. Comparison of the staining patterns of insulin, glucagon, and anglerfish peptide Y in the islet organ to PAM immunoreactivity suggests a distribution of forms of PAM enzyme in insulin and anglerfish peptide Y-containing cells, but no overlap with glucagon-producing cells. The results also indicate that PAM immunoreactivity is widely distributed in the brain, pituitary and islet organ of anglerfish in cells that contain peptides that require presence of a C-terminal glycine for amidation.     

Feeding habits of anglerfish,Lophius budegassa (Spinola, 1807) in the Adriatic Sea,north‐eastern Mediterranean

Stomach contents of 283 anglerfish (Lophius budegassa), collected in the Adriatic Sea (north‐eastern Mediterranean) from experimental trawl surveys in 2005 and 2006, were examined to assess their diet as influenced by fish size, sex and water depth. Changes in food quantities in the stomach were observed, the percentage of empty stomachs decreasing with increasing body size and depth. No differences were found between male and female diets. The anglerfish is essentially an ‘opportunistic feeder’ that consumes mainly fishes, crustaceans and molluscs. Fishes were the primary food consumed by all size classes; the favourite prey was Merluccius merluccius (TL >150 mm for medium and large anglerfish) and Gaidropsarus biscayensis (TL <150 mm for smaller anglerfish). However, the proportion of fish species and molluscs changed with the body size of the anglerfish. The trophic level of L. budegassa estimated in the study area reached a mean value of 4.38, confirming that the species was a carnivore with a preference for large decapodes, cephalopods and fish.     

Application of data‐limited assessment methods on black anglerfish (Lophius budegassa; Spinola, 1807) stocks in the Mediterranean Sea

A survey‐based assessment of an eastern Mediterranean data‐limited black anglerfish (Lophius budegassa; Spinola, 1807) stock was carried out to elucidate its population and exploitation trends. A catch‐based method was also applied to estimate its maximum sustainable yield (MSY). The effect on the long‐term spawning stock biomass and yield of a wide range of exploitation regimes (combinations of F and selectivity) was investigated using an age‐structured population model parameterised for Mediterranean anglerfish stocks. The analysis indicated an increasing trend of anglerfish fishing mortality (F) in the eastern Mediterranean from the mid‐1990s onwards, and that recent catches were 41% higher than the median MSY estimate. Catching Mediterranean anglerfish at least three years after they mature at an F = 0.4–1 year^?1 would ensure high yields at sustainable levels of stock depletion. Examination of the empirical exploitation regimes in five anglerfish stocks across the Mediterranean Sea illustrates their unfulfilled potential for higher sustainable yields, mainly due to overexploitation of juveniles.     

Morphological and molecular characterization of separated pelagic eggs from Lophius litulon (Lophiiformes; Lophiidae)

Free‐floating eggs of Lophius litulon were collected using plankton nets after their release from a pelagic egg mass. The eggs were identified based on molecular analysis and several morphological characteristics. These rare, separated eggs have not been reported previously and represent the first such finding for Lophiiformes.     

Feeding Ecology of Black-bellied Anglerfish Lophius budegassa in the Central Aegean Sea,Turkey

Journal of Ichthyology - Anglerfishes Lophius spp. are gaining high economic value day by day and becoming demand species worldwide. The black-bellied anglerfish, Lophius budegassa (Spinola, 1807)...     

Large vertical movements by a goosefish,Lophius americanus,suggests the potential of data storage tags for behavioral studies of benthic fishes

The extensive periodic vertical movements of up to 14 h and 209 m observed in this study for an individual goosefish, Lophius americanus, challenges previous assumptions about the benthic and highly sedentary behavior of the species as well as of other lophiids. Researchers should consider conducting similar data storage tagging studies with other benthic fishes to test assumptions of sedentary behavior.     

Selectivity of a 50-mm diamond mesh knotless polyethylene codend for commercially important fish species in the Aegean Sea

This research investigated effects of changing the diamond mesh size on codend selectivity in Mediterranean fisheries. The selectivity of a typical 50‐mm diamond knotless polyethylene (PE) codend used in the Turkish fishery in the Aegean Sea was measured for commercially important species, in particular hake (Merluccius merluccius), horse mackerel (Trachurus trachurus), anglerfish (Lophius piscatorius) and John Dory (Zeus faber). Fishing trials were carried out on the commercial trawler ‘Hapulo?lu’ between 9 and 12 December 2006 using a modified trawl net. Selectivity data were collected by the covered codend method and analysed by means of a logistic equation (Maximum Likelihood Method). The mean selectivity curve was estimated from individual hauls, taking between‐haul variations into account. Mean mesh size of the codend was 49.4 mm as measured by digital calliper. Mean values for 50% retention length of hake and horse mackerel were estimated to be 11.4 and 15.6 cm total length; corresponding selection ranges were 4.1 and 5.5 cm respectively. The 50‐mm diamond mesh codend showed adequate selectivity compared to the minimum landing size (MLS) for horse mackerel, while for hake it selected specimens in a size range far lower than the MLS. No selectivity values could be determined for anglerfish or John Dory. To design a more selective codend for the Turkish demersal trawl fishery, not only mesh size regulations but also other codend characteristics and netting material properties must be urgently considered.     

Geographic, seasonal and bathymetric distribution of demersal fish species in the eastern Mediterranean

The distributional abundance of three demersal fish species, Merluccius merluccius, Mullus barbatus and Lophius budegassa, was studied as a function of sampling season, bathymetry and geographic area. Data were collected during research trawl surveys in the Aegean and Ionian seas under the same sampling scheme, thereby allowing comparisons to be made on the mean regional densities in numbers and biomass of these three commercially important species in Greek waters. Results indicated that European hake, M. merluccius, demonstrated a wide bathymetric and geographic distribution, with specimens encountered in all regions between 20 and 500 m depth, although density was found to be highest usually between 101 and 200 m. The mean regional density of hake was observed to vary seasonally, being higher mainly in winter. Red mullet, M. barbatus, was distributed in shallow water depths (<100 m) throughout the Greek seas, particularly in the northern part of the Aegean Sea. Abundance of this species steadily decreased with increasing depth. The geographic distribution of anglerfish, L. budegassa, was found to be restricted to the central and northern part of the Aegean Sea, with the highest mean densities encountered in the Thermaikos Gulf and in intermediate water depths between 101 and 200 m. Spatial patterns of observed density are assumed to be attributed mainly to prevailing topographic and hydrographic conditions and related biological productivity levels.     

Regulation of hormone biosynthesis in cultured islet cells from anglerfish

Summary The effects of glucose and arginine on islet hormone biosynthesis were investigated using primary cell cultures prepared from islets of the anglerfish (Lophius americanus). After dispersion under sterile conditions, islet cells were maintained at 23° C in medium containing RPMI 1640 with Hanks' buffer, pH 7.5, modified by the adjustment of glucose (to 0.56 or 5.6 mM) and arginine (to 0.1, 1.15, or 10 mM) with the addition of 10% fetal bovine serum (dialyzed, heat inactivated) and penicillin/streptomycin. After 48 h, media were replaced by incorporation media containing [¹⁴C]isoleucine and [³H]tryptophan and incubated for an additional 8 h under otherwise identical conditions. Culture samples (cells plus media) were extracted, desalted, and gel filtered to identify and quantitate [¹⁴C]insulin, [³H]glucagon(s) plus [³H]somatostatin-28, and [³H]somatostatin-14 were In some experiments, [¹⁴C]insulin, [³H]glucagon(s), [³H]somatostatin-28, and [³H]somatostatin-14 were separated by high performance liquid chromatography. Raising the medium glucose from 0.56 (control) to 5.6 mM resulted in an augmentation in incorporation of [¹⁴C]isoleucine into insulin and an augmentation of [³H]tryptophan into glucagon(s) and somatostatin-14, but no change in incorporation of [³H]tryptophan into somatostatin-28. Raising the concentration of arginine from 0.1 to 1.15 or 10 mM resulted in a dose-dependent inhibition of labeled amino acid incorporation into all hormones except somatostatin-28. The results demonstrate the usefulness of the culture system for studying the modulation of hormone biosynthesis in anglerfish islet cells. This work was supported by Grants AM 16921 and AM 26378 from the National Institutes of Health, Bethesda, MD.     

Structural characterization of peptides derived from prosomatostatins I and II isolated from the pancreatic islets of two species of teleostean fish: the daddy sculpin and the flounder

The primary structures of three peptides from extracts from the pancreatic islets of the daddy sculpin (Cottus scorpius) and three analogous peptides from the islets of the flounder (Platichthys flesus), two species of teleostean fish, have been determined by automated Edman degradation. The structures of the flounder peptides were confirmed by fast-atom bombardment mass spectrometry. The peptides show strong homology to residues (49-60), (63-96) and (98-125) of the predicted sequence of preprosomatostatin II from the anglerfish (Lophius americanus). The amino acid sequences of the peptides suggest that, in the sculpin, prosomatostatin II is cleaved at a dibasic amino acid residue processing site (corresponding to Lys61-Arg62 in anglerfish preprosomatostatin II). The resulting fragments are further cleaved at monobasic residue processing sites (corresponding to Arg48 and Arg97 in anglerfish preprosomatostatin II). In the flounder the same dibasic residue processing site is utilised but cleavage at different monobasic sites takes place (corresponding to Arg50 and Arg97 in anglerfish preprosomatostatin II). A peptide identical to mammalian somatostatin-14 was also isolated from the islets of both species and is presumed to represent a cleavage product of prosomatostatin I.     

The reproduction of anglerfish Lophius piscatorius Linnaeus from the north-west coast of Scotland

The reproductive cycle of anglerfish was studied by examining fresh material obtained from commercial landings and research vessel surveys. The general morphology and histology of the gonads are described. This species has unusual gonads. The testes are tubular, and beanshaped in transverse section. The maturation process of the testis is similar to that of most other teleosts. The ovaries are confluent and form a single, flattened tube. During maturation, the width and, in particular, the length of the ovaries increases dramatically. A gelatinous matrix is produced during the maturation process, which contributes to the enormous size and weight of ripe ovaries. Ripe testes can be found throughout the year, whereas ripened ovaries were found only between November and May. Females outnumbered males in length classes greater than 70 cm and no males larger than 90 cm were found. The estimated mean length at maturity (1_50%) was 73 cm for females and 49 cm for males. Because only the large female anglerfish are capable of spawning, and because virtually all large anglerfish are female, trends in their abundance resulting from commercial exploitation should be monitored with care.     

Polymorphic dinucleotide microsatellites for the Mediterranean angler species (Lophiidae)

A microsatellite‐enriched genomic library was obtained from black‐bellied angler Lophius budegassa and six polymorphic dinucleotide markers were successfully optimized. These markers showed levels of polymorphism ranging from 0.363 to 0.662 and allele numbers ranging from three to seven. These markers were also found to successfully amplify in the closely related Lophius piscatorius (angler) and thus appear to be useful for genetic stock structure analysis in both species.     

New records of anglerfishes (Antennariidae) from New Zealand

Abstract

Three species of anglerfish, Histrio histrio, Antennarius ocellatus, and A. nummifer, are newly recorded from northern New Zealand waters. A. tridens is redescribed, and variations in its colour pattern are illustrated.     

Discrepancies in phylogeographical patterns of two European anglerfishes (Lophius budegassa and Lophius piscatorius)

In order to investigate the relative importance of historical processes and life-history traits in shaping the present-day genetic structure of European anglerfishes, 382 Lophius piscatorius and 134 Lophius budegassa were sequenced on the 5' end of the mitochondrial control region. Both species showed a limited genetic structure and some evidence of a demographic expansion that probably occurred not at the end of the Last Glacial Maximum, but earlier in the Pleistocene. The main discrepancy between the two anglerfishes concerned the genetic structure between Atlantic and Mediterranean populations, with weak but significant differentiation observed only in L. budegassa. This genetic structure was congruent with the existence of a phylogeographical break previously reported in several marine species across the Almeria-Oran front. The contrast observed between both anglerfishes was supposed to be induced by a possible more ancient (re)colonisation of the Mediterranean Sea by L. budegassa. Finally, the limited genetic structure and lack of isolation by distance observed in both species suggested high larval dispersal capacities that probably overwhelm the influence of the bathymetric distribution range on migrations of adults and juveniles.