Association of the abundance and vertical distribution of tuna and beakfish in the southeast of the Caribbean sea

The longline hooks suspension depth was estimated using the Mechanic Imitation of Flexible Systems method. The vertical distribution of tunas and billfish was determined by the relative abundance index, obtained from the catch by 11 to 25 m -long longline vessels, -based at Cumaná, Venezuela, South-eastern Caribbean Sea in depths of 65 to 142 m. The CPUE was evaluated per species, according to depth. High values were found for most of the captured species in the layer from 105 to 125 m. Yellowfin tuna (Thunnus albacares) showed the highest yield (3.37 fish/100 hooks) and blue marlin (Makaira nigricans) the lowest (0.04 fish/100 hooks). However, the statistical comparison did not allow to reject the hypothesis of lack of depth efect (Kruskal-Wallis p > .05), and demonstrated a homogeneous distribution of yellowfin tuna (Thunnus albacares), albacore (Thunnus alalunga), bigeye tuna (Thunnus obesus), sailfish (Istiophorus albicans), white marlin (Tetrapturus albidus) and blue marlin (Makaira nigricans) in the water column. The conclusion is that fish concentration in the Southern border of the Caribbean Sea is possibly due to several hydroclimatic factors--which affect tuna and billfish catching--such as water temperature and dissolved oxygen concentration which limit the distribution according to depth.     

DNA barcoding of billfishes

DNA barcoding is a method promising fast and accurate identification of animal species based on the sequencing of the mitochondrial c oxidase subunit (COI) gene. In this study, we explore the prospects for DNA barcoding in one particular fish group, the billfishes (suborder Xiphioidei--swordfish, marlins, spearfishes, and sailfish). We sequenced the mitochondrial COI gene from 296 individuals from the 10 currently recognized species of billfishes, and combined these data with a further 57 sequences from previously published projects. We also sequenced the rhodopsin gene from a subset of 72 individuals to allow comparison of mitochondrial results against a nuclear marker. Five of the 10 species are readily distinguishable by COI barcodes. Of the rest, the striped marlin (Kajikia audax) and white marlin (K. albida) show highly similar sequences and are not unambiguously distinguishable by barcodes alone, likewise are the three spearfishes Tetrapturus angustirostris, T. belone, and T. pfluegeri. We discuss the taxonomic status of these species groups in light of our and other data, molecular and morphological.     

Sex ratio and reproductive condition of four istiophorid billfishes in tropical regions of the eastern North Pacific Ocean: with special reference to striped marlin Kajikia audax (Philippi, 1887)

Sexual differences in the distribution pattern, sex ratio and the gonad condition of four istiophorid billfishes were investigated in three different tropical areas of the eastern North Pacific Ocean from September to November 2004. Sex ratios of striped marlin Kajikia audax were equal (female : male = 11 : 11) in the open‐ocean area (16–18°N, 118–134°W), biased to males (32 : 62) in the near‐continental area (13–16°N, 103–107°W), and biased to females (19 : 6) in the near‐equatorial area (5°N, 104–120°W). Sex ratios of sailfish Istiophorus platypterus in the near‐continental area and shortbill spearfish Tetrapturus angustirostris in the open‐ocean area were not biased from 1 : 1 (43 : 36, 11 : 13), and that of blue marlin Makaira nigricans in the near‐equatorial area was biased to females (14 : 1). Reproductively active females were found for striped marlin, sailfish and shortbill spearfish. Striped marlin showed a specific spawning area (the near‐continental area), and sexual dimorphism in its temporal distribution pattern, which was presumably related to reproduction. On the other hand, the limited distribution with evidence from spawning of sailfish and shortbill spearfish imply that these species complete their life history within limited areas.     

Lunar phase and catch success of the striped marlin (Tetrapturus audax) in sport fishing at Los Cabos, Baja California Sur, Mexico

The influence of the lunar phases on the catch-per-unit effort (CPUE) of the striped marlin (Tetrapturus audax) captured by the Cabo San Lucas, Baja California Sur, Mexico sport-fishing fleet from October 1987 to June 1989 was analyzed. The information is from 3,377 fishing trips by 13 vessels that represent about 10% of the fleet. The analysis of the CPUE showed a maximum in January 1988 and a minimum in February 1989. Taking into account the knowledge of the factors that had influence on the fishing success is important in the resource management. No significant difference during the full moon compared with results during other lunar phases was found.     

Development of Anguillicola crassus (Dracunculoidea, Anguillicolidae) in experimentally infected Balearic congers Ariosoma balearicum (Anguilloidea, Congridae).

The development of Anguillicola crassus in experimentally infected Ariosoma balearicum (Anguilloidea, Congridae) kept in seawater was studied in the laboratory. In parallel trials the effect of water salinity on the development of larval A. crassus in European eels Anguilla anguilla was also investigated using eels kept in seawater of a salinity of 34 per thousand. Both eel species were orally inoculated with L3 larvae of A. crassus and then maintained for up to 3 mo at 18 degrees C in seawater. 110 d post infection, no adult but larval (L3 and L4) stages of A. crassus were detected in the swimbladder wall of Balearic congers, although this period of time was sufficient for the parasites to develop to the adult stage in European eel kept in seawater. The results presented suggest that the definitive host specificity of A. crassus comprises species of the family Anguillidae (i.e. the genus Anguilla), but not members of the Congridae. Theoretically however, A. balearicum might serve as a metaparatenic host. Factors determining the definitive host range of A. crassus remain to be elucidated. Water salinity does not seem to act as a factor affecting definitive host specificity once the parasite has become ingested by the eel.     

东南太平洋金枪鱼延绳钓主要渔获种类垂直分布

研究延绳钓渔获物的垂直分布特征,可以帮助人们制定有效措施减少兼捕鱼种的渔获率,更好地了解大洋生态系统结构,并为基于生态系统的渔业管理提供参考.本研究根据2013年9月-2014年1月我国金枪鱼科学观察员在东南太平洋采集的延绳钓钩位深度数据和主要渔获种类的钓获钩位数据,分析了各钩位的上浮率和钓获鱼种的垂直分布,比较了不同鱼种垂直分布的差异.结果表明: 钓钩相对上浮率变化范围为8.9%～17.1%,平均相对上浮率为13.5%;14种渔获物钓获深度范围差异较大,斑点月鱼的平均钓获深度最深,鲣鱼最浅;除黄鳍金枪鱼和条纹四鳍旗鱼外,其他兼捕鱼种钓获深度均与长鳍金枪鱼(目标鱼种)具有显著性差异.
     

Intra- and interspecific agonistic behavior of the subterranean termite Microcerotermes crassus (Isoptera: Termitidae)

The aim of our study was to investigate the intra- and interspecific agonistic behaviors exhibited by the worker and soldier castes of the subterranean termite Microcerotermes crassus Snyder (Isoptera: Termitidae). Aggression between M. crassus colonies from different field locations and also against three termite species--Coptotermes gestroi (Wasmann), Globitermnes sulphureus Haviland, and Odontotermes sp.--were observed in the laboratory. Termite responses were tested in paired combination of castes (soldiers versus soldiers, soldiers versus workers, and workers versus workers) consisting of 10 individuals each. Significant agonistic behaviors were observed only in encounters between pairings of different termite species. M. crassus was aggressive toward individuals from different species but not toward individuals from different M. crassus colonies. Mortality of M. crassus reached 100% in most of the interspecific encounters. However, no or low mortality was recorded in the intraspecific pairings.     

A new genus and species of opisthogonimid (Digenea) of Liophis anomalus (Serpentes: Colubridae) from Uruguay

During a study on the helminth fauna of Liophis anomalus specimens deposited in the Reptile Collection of the Secci6n Zoología Vertebrados, Facultad de Ciencias, Uruguay, a new genus of Opisthogoniminae was found. Paracotyletrema n. gen. is described from the buccal cavity and esophagus of specimens from Departamento de Flores, Uruguay. This new genus differs from the other 2 Opisthogoniminae, Opisthogonimus and Westella, by having much smaller body size; maximum width at level of posterior end of oral sucker; oral sucker length more than one-fourth of body length; oral sucker and acetabulum separated by a distance of about the diameter of pharynx; cirrus pouch length more than half of body length; and testes in completely coincident zones. The type and only species, Paracotyletrema poncedeleoni n. gen., n. sp., is defined by the following diagnostic characters: mean oral sucker length one-third to one-half of body length; cirrus pouch of about body length, contorted, mainly acetabular; large, round testes in nearly adjacent fields, and an ovary nearly adjacent to right testis. Besides the type locality, Paracotyletrema poncedeleoni has been found in L. anomalus specimens from the Departamentos of Artigas and Treinta y Tres; therefore, it has a widespread distribution in Uruguay.     

A new species of Opisthioglyphe (Trematoda: Telorchiidae) from gall bladder of turtles in Malaysia

Opisthioglyphe sharmai n. sp. is described from the gall bladder of the Malayan box turtle, Cuora amboinensis, and the black marsh turtle, Siebenrockiella crassicollis, in Malaysia. The new species is morphologically similar to Opisthioglyphe ranae and some other members of the genus parasitic in amphibians and reptiles. Opisthioglyphe sharmai n. sp. is easily differentiated from all other members of the genus by the cirrus sac extending posterior to the ventral sucker, while in all previously known species the cirrus sac is entirely or mostly preacetabular with the base of the structure not reaching beyond mid-line of the ventral sucker. Despite the overall stable morphology, O. sharmai n. sp. is characterized by highly variable arrangement of testes, from tandem to opposite. It is only the second representative of the genus described from turtles and the first species of Opisthioglyphe parasitic in gall bladder, while all previously described members of the genus are parasitic in the intestine of their hosts.     

Vaccination of eels (Anguilla japonica and Anguilla anguilla) against Anguillicola crassus with irradiated L3

The original host of the swimbladder nematode Anguillicola crassus, the Japanese eel (Anguilla japonica) and the recently colonized European eel (Anguilla anguilla) were immunized with 40 irradiated (500 Gy) 3rd-stage larvae (L3) of this parasite and challenged with an infection of 40 normal L3. The immunization induced a significant reduction of the number of adult worms developing from the challenge infection in A. japonica, but not in A. anguilla. The induced resistance (calculated using the relation of the number of adult worms in immunized eels and in non-immunized control eels) in A. japonica was 87.3%+/-30.4%. Following a single infection, the percentage of adult worms found in A. japonica was lower as compared to A. anguilla, and the few adult worms were much smaller, revealing a lower susceptibility of A. japonica to A. crassus in comparison to A. anguilla. Both eel species developed an antibody response against A. crassus, but the level of antibody responses was not positively correlated with the protection against infection, suggesting that the antibody response is not a key element in resistance of eels against A. crassus. This study suggests that the original host of A. crassus is able to mount efficient protective immune responses against its parasite, whereas the newly acquired host seems to lack this ability.     

Margolisius abditus n. gen., n. sP. (Copepoda: Lernaeopodidae) from gill lamellae of a remora (Remora remora) collected in the Gulf of California

Margolisius abditus n. gen., n. sp. (Copepoda: Lernaeopodidae) is described from female specimens collected from gill lamellae of a remora, Remora remora (L.), captured in the Gulf of California near Punta Arena, Baja California. Comparison of this species with 13 lernaeopodid genera with which it shares (a) absence of posterior trunk processes; (b) presence of a relatively long cylindrical cephalothorax, usually reflected along the dorsal surface of the trunk; and (c) a marine habitat showed that it cannot be placed in any of them, thus necessitating establishment of a new genus. Margolisius abditus n. sp. is the smallest known lernaeopodid species, its ovigerous females measuring about 0.5 mm in total length.     

Description of Brachylecithum mackoi n. sp. (Digenea: Dicrocoeliidae) from the European hedgehog, Erinaceus europaeus (Insectivora: Erinaceidae)

A new hepatic dicrocoeliid species, Brachylecithum mackoi n. sp. (Digenea, Dicrocoeliidae), is described from the European hedgehog, Erinaceus europaeus (L.) (Insectivora, Erinaceidae). An infected host was found in the Mediterranean island of Elba (Italy), and more than 60 individuals were isolated from the biliary ducts. The holotype and 55 paratypes were examined. Brachylecithum mackoi n. sp. differs from congeneric species found in mammal hosts by having well-developed lappets in the ventral sucker, a sloping uterus between anterior testis and acetabulum, no overlap between vitellaria, and metrical features in the body size, sucker diameters, cirrus sac, and size of eggs. The only other Brachylecithum species of erinaceids in Europe and Africa, Brachylecithum aetechini Dollfus, 1951, differs from the new species in the above-mentioned morphological characters, greater dimensions of the body, and oral sucker, pharynx, cirrus sac, and egg dimensions. The presence of B. mackoi n. sp. in Elba Island is discussed in the light of apparent host specificity of erinaceid dicrocoeliids and geographical distribution of Palearctic and Ethiopian Erinaceidae.     

Helminth position within the intestine of naturally infected pike (Esox lucius) relative to host stomach contents

The positions of 3 cestode species, Triaenophorus crassus Forel, Triaenophorus nodulosus (Pallas), and Proteocephalus pinguis LaRue, and a nematode, Raphidascaris acus (Bloch), within the intestine of naturally infected pike (Esox lucius L.) were evaluated with respect to the presence or absence and state of digestion of host stomach contents. The positions of scolices and strobilae of the cestodes did not vary with respect to host stomach contents. By contrast, R. acus was anterior (near the stomach) when the stomach contained partially digested items, posterior when the stomach was empty, and in an intermediate position when the stomach contained only intact items. These results are interpreted as migration of R. acus, but not T. crassus, T. nodulosus, or P. pinguis, in response to feeding activity of the host. Adult and larval R. acus migrated, but the extent of migration was reduced in hosts harboring T. crassus, more so for larval than adult R. acus.     

The influence of food competition and host specificity on the transmission of Triaenophorus crassus (Cestoda) and Cystidicola farionis (Nematoda) to Coregonus lavaretus and Coregonus albula (Pisces:Coregonidae) in Finland

As a superior competitor for planktonic food, vendace (Coregonus albula), when abundant, is expected to displace whitefish (Coregonus lavaretus) from feeding on plankton and to force it to rely more on benthic food. The predicted result would be a reduced abundance of the copepod-transmitted cestode Triaenophorus crassus in whitefish, but an increase in the abundance of the nematode Cystidicola farionis transmitted via benthic amphipods. We studied the occurrence of both parasites in whitefish during 1991-1996 in three interconnected areas at Lake Saimaa, Finland, where the densities of the vendace stocks varied due to natural fluctuation in year-class strengths. In accordance with our hypothesis, some indication of the effect of the density of the vendace population on abundance of C. farionis infection in whitefish was found, but not in the case of T. crassus. Only 0.2% of vendace were infected with T. crassus, while up to 100% of the whitefish in the yearly samples harboured the parasite. In further experiments we clarified which copepod species in Lake Saimaa act as first intermediate hosts of T. crassus, and verified from stomach samples the exposure of both whitefish and vendace to those species. Experimental infections indicated that the infectivity of T. crassus is lower for vendace than for whitefish. We suggest that the reason why vendace stock density does not affect T. crassus infection in whitefish is that T. crassus is transmitted in littoral areas during a short period in spring. At that time of the year copepods are abundant and available to both whitefish and vendace, but since the parasite is less infective to vendace. they do not become infected. At other times of the year, dense vendace stocks may force whitefish to shift to benthic food, which includes amphipods transmitting C. farionis. During vendace stock decline, whitefish may, however, continue to feed on plankton and avoid exposure to C. farionis.     

Cone visual pigments and retinal mosaics in the striped marlin

Three different cone photoreceptor visual pigments in the retina of striped marlin Tetrapturus audax were found with the aid of microspectrophotometry. This provides the first evidence for the basis of colour vision in the Istiophoridae. Furthermore, regional variations in photoreceptor density, type and spatial arrangement indicate differing visual capabilities along different visual axes.     

Regulation of Anguillicola crassus (Nematoda) infrapopulations in their definitive host, the European eel, Anguilla anguilla

The parasitic nematode Anguillicola crassus was recently introduced into populations of the European eel, Anguilla anguilla. We investigated, under experimental conditions, the regulation of A. crassus infrapopulations. We tested the effects of (1) the resource-limited habitat of the parasite and (2) the coexistence of several developmental stages in its niche (the swim-bladder) on the composition of the infrapopulations. The results revealed that the respective effects of these factors differed substantially during the course of the infection. Third-stage larvae (L3s) establishment would not be constrained by the size of the swim-bladder. Their moult to fourth-stage larvae (L4s) would be accelerated as the number of L3s increased. The moulting time of L4s to adults would be reduced by males and would be constrained by the size of the swim-bladder. However, the moult of L4s to adults and their further development would be synchronized with those of the opposite sex. At the time of mating, the number of males and the body weight of adults would depend on the size of the swim-bladder. Soon after the laying of eggs, the developmental constraint on the late L3s would decrease. When adults die, constraints would cease and late larval stages would moult to become adults.     

Comparative morphogenesis of the cephalic structures of the acuariid nematodesStammerinema soricis (Tiner, 1951),Antechiniella suffodiax (Beveridge & Barker, 1975) n. g., n. comb. andSkrjabinoclava thapari (Teixeira de Freitas, 1953)

Summary Stammerinema soricis (Tiner, 1951) is reported fromSorex araneus L. from a new geographic locality, Sologne, France. Comparison of the ontogenesis of the cephalic structures of this species with two other acuariids of mammals,S. suffodiax Beveridge & Barker, 1975 andS. thapari (Teixeira de Freitas, 1953), shows that these three species, formerly included in the same genus, represent three distinct genera:Stammerinema Osche, 1955, parasitic in holarctic insectivores;Antechiniella n. g. parasitic in Australian marsupials and rodents; andSkrjabinoclava Sobolev, 1943, parasitic in neotropical carnivores and in birds. The two generaStammerinema andAntechiniella belonging to different subfamilies of the Acuariidae, are derived from acuarioids which have evolved mainly in birds, hosts which harbour ancestral forms. ac]19850610