Chelidonichthys Lucerna Research Articles

A revision of Lomasoma Manter 1935 (Digenea: Fellodistomidae), with new data on the type-specimens of four species and the description of L. triglae n. sp. from Chelidonichthys lucernus (L.) (Pisces: Triglidae) in the Western Mediterranean

Type-specimens of Lomasoma wardi (Manter, 1934), L. monolenei (Manter, 1934), L. gracile (Manter, 1934) (emend.) and L. stefanskii Dollfus, 1960 were studied with special reference to the structure of their body margins and terminal genitalia. Illustrations and a partial redescription is given for each of these species. The new data obtained enabled the recognition and description of L. triglae n. sp. from the tub gurnard Chelidonichthys lucernus (L.) in the Western Mediterranean. Differences between the species of the genus are tabulated. An interpretation of the function of the muscular lobes on the margins of the body of Lomasoma spp. is presented, and comments are made on the structural homogeneity or diversity of different morphological features.

Body shape and trawl cod end selectivity for nine commercial fish species

This study investigates the catch components of a commercially used demersal trawl cod end in Izmir Bay, and reveals some of the morphological characteristics of nine commercial fish species; red mullet (Mullus barbatus), hake (Merluccius merluccius), whiting (Merlangius merlangus euxinus), poor cod (Trisopterus minutus capelanus), tub gurnard (Trigla lucerna), common pandora (Pagellus erythrinus), axillary sea bream (Pagellus acarne), picarel (Spicara smaris) and annular sea bream (Diplodus annularis) in relation to mesh size and shapes. Furthermore selectivity of 40-mm polyethylene netting cod end for red mullet, hake, common pandora, axillary sea bream, picarel and annular sea bream is presented. The results are discussed in a way to understand the probable effects of fish body shape on mesh selectivity.

Embryonic and larval development of the tub gurnard Trigla lucerna (Pisces: Triglidae)

The embryonic and early larval development of the laboratory-reared tub gurnard, Trigla lucerna are described. The eggs ranged in diameter from 1·33 to 1·40 mm, with a mean of 1·36±0·236 mm, were pelagic and spherical with a homogeneous and unsegmented yolk. There was single oil globule in the eggs. Globule ranged in diameter from 0·25 to 0·29 mm (mean 0·28±0·012 mm). Embryonic development lasted 115 h 2 min at mean temperature 13·5 °C. Newly-hatched larvae were 3·09±0·014 mm in total length. Absorption of the yolk sac was complete after the sixth day, when larvae reached 4·85±0·015 mm in total length. The only character for identifying eggs among species could be diameter, since the values obtained are lower than those obtained for Eutrigla gurnardus and Aspitrigla cuculus, but larger than those for Trigloporus lastoviza. The length of newly hatched yolk-sac larvae of tub gurnard is significantly lower (t-test, P<0·05) than those of most of the other gurnard species. Characters likely to help in identification of species will probably prove to be the length, shape and pigmentation of the pectoral fin, and the degrees of development of spiny armature on the head.

Changes in the Tagus nursery function for commercial fish species: some perspectives for management

The Tagus estuary has long been subjected to several human activities and uses. Changes in the estuarine fish community were evaluated based on beam trawl surveys in 1978–1980 and 1994–1996. There was a decrease of abundance of many species that use the Tagus as a nursery, namely bib (Trisopterus luscus), five bearded rockling (Ciliata mustela), tub gurnard (Trigla lucerna), and flounder (Platichthys flesus), possibly due to reduction of the water quality. In 1994–1996, only sea bass (Dicentrarchus labrax), sole (Solea solea) and Solea senegalensis Kaup, 1858, were found within the nursery grounds, showing an irregular pattern of abundance. Condition and vacuity index were highly variable. The major problems affecting the fish community, namely pollution, fishery regulation and waterflow regulation, are discussed in relation to the management and conservation of this estuarine system.

Trophic relationships between two gurnards Trigla lucerna and Aspitrigla obscura from the western Mediterranean

The feeding habits of Trigla lucerna L. (1758) and Aspitrigla obscura L. (1764) (Pisces: Triglidae), off the coast of the Gulf of Valencia (Spain), were investigated between October 1989 and January 1991. The two species examined in this study appear to have distinct feeding types, based on the species composition of prey and the frequency of occurrence of major food items. Tub gurnard had a more diverse diet and fed mainly on crustaceans (mysids and decapods), teleosts and molluscs, whilst long fin gurnard were less piscivorous and fed mainly on mysids and natantids. No significant differences were found in the annual variation of vacuity coefficient for either species. Diet composition in these species did not show great changes with either season and size of fish. There was little dietary overlap between these two species.

Myofibrillar ATPase in the various red and white trunk muscles of the tunny ( Thunnus thynnus L.) and the tub gurnard ( Trigla lucerna L.)

1. 1. Measurements of myofibrillar adenosine triphosphatase activities have been made from the various red and white muscles of the tunny ( Thunnus thynnus L.) and the tub gurnard ( Trigla lucerna L.). 2. 2. The ratios of the activities of the white to red muscle were found to be 4·4 times in the case of the tub gurnard and 2 times in the case of the tunny. 3. 3. The activity of the superficial red muscle was found to be twice as high in the tunny as in the tub gurnard although the activities in the white muscle were similar. 4. 4. No difference in specific activity was found between the superficial and deep red muscles of the tunny. 5. 5. These results are discussed in terms of the division of labour between fish myotomal muscles.