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

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Abstract

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.

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... In the case of platforms in the Mediterranean, these mainly consist of scorpaenid species from the genus Scorpaena (Fabi et al. 2004) that are possibly attracted by shelter or food availability. Scorpaenids are known to be highly selective predators and principally feed on crustacean decapods (Harmelin-Vivien et al. 1989;Follesa et al. 2004;Morte et al. 2001), which are also commonly preyed on by soft-bottom scorpaeniforms, for instance triglids (Colloca et al. 1994;Morte et al. 1997;Nouvel 1950). Both scorpaenids and triglids are highly abundant near platforms in the Adriatic Sea (Andaloro et al. unpublished data). ...
... PERMANOVA was also performed to detect differences between five predator size classes (two-factor analysis: predators 9 size classes) as follows: size class I B 140 mm, size class II = 141-180 mm L T , size class III = 181-220 mm L T , size class IV = 221-260 mm L T , size class V [ 260 mm L T . Such intervals were identified taking into account the size at which each species undergoes sexual maturity: (1) S. notata undergoes maturity at about 10-14 cm L T (Scarcella et al. 2011b); (2) C. lucerna starts maturing at sizes [180 mm L T (Montanini et al. 2008;Morte et al. 1997). The specimens of S. porcus collected in our study, except for only one specimen of 90 mm L T , exceeded the size at first maturity reported in literature (i.e. ...
... A comparison between the diets of the three predators has evidenced the widest prey variety in C. lucerna; said array is mainly made up of epibenthic and infaunal organisms encompassing a variety of crustaceans, molluscs and fish that are typical of soft bottoms. Said feeding behaviour is in line with what reported in literature for this species in other areas (Collignon and Aloncle 1960;Colloca et al. 1994;Costa 1988;Morte et al. 1997;Stagioni et al. 2011), although prey composition may vary depending on local resource availability. ...
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Trophic relationships between Scorpaena porcus, S. notata and Chelidonichthys lucerna collected near natural gas platforms were investigated for the first time in central Adriatic Sea from July 2005 to May 2006. Sampling was repeated at control sites on soft bottom where, however, only C. lucerna occurred. All of the three predators showed diet specialization for crustaceans, with high overlap for angular crab Goneplax rhomboides. The widest prey variety, consisting mainly of epibenthic and infaunal organisms, was detected in C. lucerna, whose feeding behaviour resulted not to be affected by the presence of platforms. Burrowing shrimp Alpheus glaber, hairy crab Pilumnus hirtellus, bivalve Corbula gibba, and European anchovy Engraulis encrasicolus discriminated S. porcus diet, while thalassinid Jaxea nocturna discriminated S. notata diet. The occurrence of E. encrasicolus as natural prey of S. porcus is discussed. Overall, predators like scorpaenids, which live in strict association with platforms in the study area, seem to rely on soft bottom prey items rather than exploiting resources from the platforms, thus competing with soft-bottom predators (i.e. triglids) for the same resources.
... These fish are an important component of demersal assemblages in terms of biomass in both the eastern and western Mediterranean basins (Jukic-Peladic et al. 2001, Labropoulou and Papaconstantinou 2004, Massuti and Reñones 2005. Several studies have focused on the life-history traits of these species, such as growth (Papaconstantinou 1981, 1984, Colloca et al. 2003 and spawning (Papaconstantinou 1983, Vallisneri et al. 2011, 2012, feeding (Colloca et al. 1994, Morte et al. 1997, Terrats et al. 2000, as well as on other aspects related to the trophic and habitat partitioning among species (Serena et al. 1990, Tsimenides et al. 1992, Colloca et al. 2010. From an ecological perspective, the 8 gurnard species, along with the closely related African armoured searobin, Peristedion cataphractum, play similar roles in the trophic web, feeding mainly on epibenthic crustaceans (Colloca et al. 1994). ...
... From an ecological perspective, the 8 gurnard species, along with the closely related African armoured searobin, Peristedion cataphractum, play similar roles in the trophic web, feeding mainly on epibenthic crustaceans (Colloca et al. 1994). Interspecific competition for food is reduced by species segregation across gradients of prey size and habitat type (Morte et al. 1997, Colloca et al. 2010, Montanini et al. 2017. ...
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In this study we investigated the spatio-temporal distribution of gurnards (8 species of Triglidae and one species of Peristediidae) in the northern Mediterranean Sea using 22 years of MEDITS bottom trawl survey data (1994-2015). Gurnards showed significant differences in terms of abundance, dominance and composition among geographical sub-areas and ecoregions, with the highest relative biomass (BI y) being found in Malta, eastern Corsica, the Balearic Islands and the eastern Ionian Sea. The lowest gurnards BI y were observed in the highly exploited areas of the western Mediterranean and the Adriatic Sea, where the largest number of species with a negative linear trend in BI y was also found. The temporal trends in species abundances highlighted a general decrease for the coastal species (C. lucerna, C. lastoviza, C. obscurus) as compared with the species inhabiting the deep continental shelf and slope (T. lyra, P. cataphractum). The results provide for the first time an overview of the spatiotemporal trend in the abundance of gurnards over the wide spatial scale of the northern Med-iterranean Sea, also suggesting the possible use of these species as indicators for monitoring the impact of fishing pressure on demersal fish assemblages. Abundancia y distribución de los gurnardos en el norte del Mediterráneo
... Dans cette dernière région, des études se rapportant à la biologie des différentes espèces de triglidés ont été réalisées dans le bassin oriental, principalement en Grèce et en Turquie où les travaux sur la biologie et l'alimentation ont été effectués par plusieurs auteurs (Papaconstantinou, 1984(Papaconstantinou, , 1986Caragitsou et Papaconstantinou, 1990, 1994Labropoulou et Platis, 1995 ;Labropoulou et Machias, 1998 ;Terrats et al., 2000 ;Icemer et al., 2002 ;Ismen et Ismen, 2004 ;Eryilmaz et Merliç, 2005 ;Ilhan et Tgoulgua, 2007). Les recherches dans le bassin occidental ont été menées particulièrement au niveau de la partie nord (Mouneimne, 1970 ;Kartas, 1971 ;Moreno et Matallanas, 1983 ;Moreno-Amich, 1992 ;Morte et al., 1997 ;Muñoz et al., 2002 ;Colloca et al., 2003). ...
... Cependant, sur les côtes égyptiennes, Faltas (1996) mentionne une augmentation hivernale de l'intensité alimentaire du grondin camard. En outre, Morte et al. (1997), qui ont relevé pendant la période de ponte une réduction du nombre des estomacs vides chez Chelidonichthys lucerna et C. obscurus en Méditerranée occidentale, pensent que les processus physiologiques n'affectent pas le comportement alimentaire de ces espèces de poissons, particulièrement durant la reproduction. ...
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Reproduction and diet of Trigloporus lastoviza (Triglidae) in the Gulf of Tunis. The reproduction and diet of the streaked gurnard Trigloporus lastoviza (Bonnaterre, 1788), the most common gurnard species in Tunisia, were studied in the Gulf of Tunis, from June 2007 to May 2008. Samples were monthly collected from different landing sites in the study area. A total of 478 females and 210 males (10.6 cm < TL < 26.0 cm) were examined to characterize the reproduction of the species. Based on the variations of the gonadosomatic index (GSI) and percentages of different gonad maturity stages, gonadic maturation occurred from September to December, and spawning took place in late December to January for both sexes. Besides, a significant difference among GSI values was evidenced, not only in terms of the various gonadic development stages (p > 0.05), but also in terms of spawning period (p > 0.05). Moreover, the hepatosomatic index (HSI) revealed that the liver size (weight) was proportionally increasing with respect to gonad maturation. The condition factor (Kc) was not found to be affected by the maturation of genital products. Size at first sexual maturity (L50) was estimated to be 16.38, 15.65 and 15.50 cm for males, females and both sexes, respectively. No significant differences were observed between male and female sizes at first maturity (p < 0.05). These data are important for stock assessment of streaked gurnard in the Gulf of Tunis and fishing regulation. The diet of the species was studied by examining the stomachs of 296 individuals. The vacuity coefficient (Cv) was estimated to be 48.3%. It showed significant differences for juveniles (TL < 15.5 cm) and adults (TL ≥ 15.5 cm). Seasonal variations were also statistically noted with juveniles and adults. In contrast, the annual Cv of these two groups was not statistically different. The diet of the streaked gurnard consisted of 19 prey types, belonging to seven phyla (Chlorophyta, Magnoliophyta, Annelida, Mollusca, Crusta�cea, Bryozoa and Teleostei). The various alimentary indices (i.e., frequency of occurrence “FO”, percentage in number “Cn”, percentage in weight “Cp” and alimentary coefficient “Q”) showed that the food bulk of the streaked gurnard was mainly composed, throughout the year, by crustaceans. Their occurrence frequencies did not show significant seasonal variations, with a maximum in autumn (100%) and a minimum in summer (85%). Among crustaceans, decapods were the preferential prey type, as they were the most important in percentage, in number and in weight. They were followed by mysidaceans and teleosts, in terms of number and weight, respectively. The diet of the streaked gurnard presented a sea�sonal heterogeneity. This seasonal variability was confirmed by Spearman rank coefficient (0.824 ≤ ρ ≤ 3.635), revealing an annual fluctuation in diet. It is worth noting that juveniles’ diet was more diversified in spring. Adults seemed to target actively big-sized prey, while juveniles seemed to feed much more when the resources are more available.
... Dans cette dernière région, des études se rapportant à la biologie des différentes espèces de triglidés ont été réalisées dans le bassin oriental, principalement en Grèce et en Turquie où les travaux sur la biologie et l'alimentation ont été effectués par plusieurs auteurs (Papaconstantinou, 1984(Papaconstantinou, , 1986Caragitsou et Papaconstantinou, 1990, 1994Labropoulou et Platis, 1995 ;Labropoulou et Machias, 1998 ;Terrats et al., 2000 ;Icemer et al., 2002 ;Ismen et Ismen, 2004 ;Eryilmaz et Merliç, 2005 ;Ilhan et Tgoulgua, 2007). Les recherches dans le bassin occidental ont été menées particulièrement au niveau de la partie nord (Mouneimne, 1970 ;Kartas, 1971 ;Moreno et Matallanas, 1983 ;Moreno-Amich, 1992 ;Morte et al., 1997 ;Muñoz et al., 2002 ;Colloca et al., 2003). ...
... Cependant, sur les côtes égyptiennes, Faltas (1996) mentionne une augmentation hivernale de l'intensité alimentaire du grondin camard. En outre, Morte et al. (1997), qui ont relevé pendant la période de ponte une réduction du nombre des estomacs vides chez Chelidonichthys lucerna et C. obscurus en Méditerranée occidentale, pensent que les processus physiologiques n'affectent pas le comportement alimentaire de ces espèces de poissons, particulièrement durant la reproduction. ...
Article
Full-text available
The reproduction and diet of the streaked gurnard Trigloporus lastoviza (Bonnaterre, 1788), the most common gurnard species in Tunisia, were studied in the Gulf of Tunis, from June 2007 to May 2008. Samples were monthly collected from different landing sites in the study area. A total of 478 females and 210 males (10.6 cm < TL < 26.0 cm) were examined to characterize the reproduction of the species. Based on the variations of the gonadosomatic index (GSI) and percentages of different gonad maturity stages, gonadic maturation occurred from September to December, and spawning took place in late December to January for both sexes. Besides, a significant difference among GSI values was evidenced, not only in terms of the various gonadic development stages (p > 0.05), but also in terms of spawning period (p > 0.05). Moreover, the hepatosomatic index (HSI) revealed that the liver size (weight) was proportionally increasing with respect to gonad maturation. The condition factor (Kc) was not found to be affected by the maturation of genital products. Size at first sexual maturity (L50) was estimated to be 16.38, 15.65 and 15.50 cm for males, females and both sexes, respectively. No significant differences were observed between male and female sizes at first maturity (p < 0.05). These data are important for stock assessment of streaked gurnard in the Gulf of Tunis and fishing regulation. The diet of the species was studied by examining the stomachs of 296 individuals. The vacuity coefficient (Cv) was estimated to be 48.3%. It showed significant differences for juveniles (TL < 15.5 cm) and adults (TL a 15.5 cm). Seasonal variations were also statistically noted with juveniles and adults. In contrast, the annual Cv of these two groups was not statistically different. The diet of the streaked gurnard consisted of 19 prey types, belonging to seven phyla (Chlorophyta, Magnoliophyta, Annelida, Mollusca, Crustacea, Bryozoa and Teleostei). The various alimentary indices (i.e., frequency of occurrence "FO", percentage in number "Cn", percentage in weight "Cp" and alimentary coefficient "Q") showed that the food bulk of the streaked gurnard was mainly composed, throughout the year, by crustaceans. Their occurrence frequencies did not show significant seasonal variations, with a maximum in autumn (100%) and a minimum in summer (85%). Among crustaceans, decapods were the preferential prey type, as they were the most important in percentage, in number and in weight. They were followed by mysidaceans and teleosts, in terms of number and weight, respectively. The diet of the streaked gurnard presented a seasonal heterogeneity. This seasonal variability was confirmed by Spearman rank coefficient (0.824 sps 3.635), revealing an annual fluctuation in diet. It is worth noting that juveniles' diet was more diversified in spring. Adults seemed to target actively big-sized prey, while juveniles seemed to feed much more when the resources are more available.
... Dans cette dernière région, des études se rapportant à la biologie des différentes espèces de triglidés ont été réalisées dans le bassin oriental, principalement en Grèce et en Turquie où les travaux sur la biologie et l'alimentation ont été effectués par plusieurs auteurs (Papaconstantinou, 1984(Papaconstantinou, , 1986Caragitsou et Papaconstantinou, 1990, 1994Labropoulou et Platis, 1995 ;Labropoulou et Machias, 1998 ;Terrats et al., 2000 ;Icemer et al., 2002 ;Ismen et Ismen, 2004 ;Eryilmaz et Merliç, 2005 ;Ilhan et Tgoulgua, 2007). Les recherches dans le bassin occidental ont été menées particulièrement au niveau de la partie nord (Mouneimne, 1970 ;Kartas, 1971 ;Moreno et Matallanas, 1983 ;Moreno-Amich, 1992 ;Morte et al., 1997 ;Muñoz et al., 2002 ;Colloca et al., 2003). ...
... Cependant, sur les côtes égyptiennes, Faltas (1996) mentionne une augmentation hivernale de l'intensité alimentaire du grondin camard. En outre, Morte et al. (1997), qui ont relevé pendant la période de ponte une réduction du nombre des estomacs vides chez Chelidonichthys lucerna et C. obscurus en Méditerranée occidentale, pensent que les processus physiologiques n'affectent pas le comportement alimentaire de ces espèces de poissons, particulièrement durant la reproduction. ...
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RÉSUMÉ. -La reproduction et le régime alimentaire de Trigloporus lastoviza (Bonnaterre, 1788), espèce de triglidés commune des côtes tunisiennes, ont été étudiés de juin 2007 à mai 2008 dans le golfe de Tunis. Pour l'étude de la reproduc-tion, 688 individus (10,6 cm < Lt < 26 cm) dont 478 femelles et 210 mâles ont été examinés. Le suivi mensuel de l'indice gonadosomatique (IGS) et de la maturité des gonades a montré que la période de maturation a lieu de septembre à décem-bre et que la ponte débute fin décembre-début janvier. Le suivi mensuel de l'indice hépatosomatique (IHS) met en évidence une augmentation des graisses dans le foie à la même période que la maturation des gonades. Le coefficient de condition (Kc) n'est pas affecté par la maturation des produits génitaux. La taille de première maturité sexuelle (L 50) a été estimée à 16,38 cm, 15,65 cm et 15,50 cm pour les mâles, les femelles et les sexes groupés, respectivement. Sur un total de 296 indi-vidus examinés pour l'étude alimentaire, près de la moitié (143) présentait un estomac vide. Le coefficient de vacuité (Cv) montre des variations saisonnières significatives. Ce dernier, déterminé chez les juvéniles et les adultes, a montré aussi des différences significatives entre ces deux groupes. L'analyse des contenus stomacaux a permis d'identifier 19 types de proies appartenant à sept phyla (chlorophytes, magnoliophytes, annélides, mollusques, crustacés, bryozoaires et téléostéens). La fréquence d'occurrence (FO), le pourcentage en nombre (Cn), le pourcentage en poids (Cp) et le coefficient alimentaire (Q) des proies ont été calculés. Les crustacés décapodes, proies préférentielles, sont les plus importants numériquement et pondéralement. Ils sont suivis numériquement par les mysidacés et pondéralement par les téléostéens. Le régime alimen-taire présente une variabilité saisonnière, celui des juvéniles étant plus diversifié au printemps. Les adultes semblent cibler activement les proies de grande taille. Les juvéniles s'alimenteraient davantage lorsque les ressources sont abondantes. ABSTRACT. -Reproduction and diet of Trigloporus lastoviza (Triglidae) in the Gulf of Tunis. The reproduction and diet of the streaked gurnard Trigloporus lastoviza (Bonnaterre, 1788), the most common gurnard species in Tunisia, were studied in the Gulf of Tunis, from June 2007 to May 2008. Samples were monthly collected from different landing sites in the study area. A total of 478 females and 210 males (10.6 cm < TL < 26.0 cm) were examined to characterize the reproduction of the species. Based on the variations of the gonadosomatic index (GSI) and percentages of different gonad maturity stages, gonadic maturation occurred from September to December, and spawning took place in late December to January for both sexes. Besides, a significant difference among GSI values was evidenced, not only in terms of the various gonadic development stages (p > 0.05), but also in terms of spawning period (p > 0.05). Moreover, the hepatosomatic index (HSI) revealed that the liver size (weight) was proportionally increasing with respect to gonad maturation. The condition factor (Kc) was not found to be affected by the maturation of genital products. Size at first sexual maturity (L50) was estimated to be 16.38, 15.65 and 15.50 cm for males, females and both sexes, respectively. No significant differences were observed between male and female sizes at first maturity (p < 0.05). These data are important for stock assessment of streaked gurnard in the Gulf of Tunis and fishing regulation. The diet of the species was studied by examining the stomachs of 296 individuals. The vacuity coefficient (Cv) was estimated to be 48.3%. It showed significant differences for juveniles (TL < 15.5 cm) and adults (TL ≥ 15.5 cm). Seasonal variations were also statistically noted with juveniles and adults. In contrast, the annual Cv of these two groups was not statistically different. The diet of the streaked gurnard consisted of 19 prey types, belonging to seven phyla (Chlorophyta, Magnoliophyta, Annelida, Mollusca, Crusta-cea, Bryozoa and Teleostei). The various alimentary indices (i.e., frequency of occurrence "FO", percentage in number "Cn", percentage in weight "Cp" and alimentary coefficient "Q") showed that the food bulk of the streaked gurnard was mainly composed, throughout the year, by crustaceans. Their occurrence frequencies did not show significant seasonal variations, with a maximum in autumn (100%) and a minimum in summer (85%). Among crustaceans, decapods were the preferential prey type, as they were the most important in percentage, in number and in weight. They were followed by mysidaceans and teleosts, in terms of number and weight, respectively. The diet of the streaked gurnard presented a sea-sonal heterogeneity. This seasonal variability was confirmed by Spearman rank coefficient (0.824 ≤ ρ ≤ 3.635), revealing an annual fluctuation in diet. It is worth noting that juveniles' diet was more diversified in spring. Adults seemed to target actively big-sized prey, while juveniles seemed to feed much more when the resources are more available.
... Wild tub gurnard shows opportunistic foraging behaviour, mainly preying on epibenthic and nectobenthic organisms. Diet composition is considered to reflect the biological community (termed biocenoesis) typical of the area (Serena, Voliani & Auteri 1998;Colloca, Ardizzone & Gravina 1994;Morte, Redon & Sanz-Brau 1997;. Tub gurnard is often found free-swimming at depths of between 10 and 150 m in areas with soft or mixed seabeds (Riedl 1991). ...
... This diet is characterized by a high degree of biodiversity, and is correlated with changes in feeding habits during growth. As tub gurnard grow, its diet changes, both in terms of prey size and type of prey, a fact that has also been attributed to its bathymetric migratory behaviour (Colloca et al. 1994;Morte et al. 1997;Stagioni et al. 2012;Vallisneri et al. 2012). Smaller individuals feed on benthic Crustacea, Amphipoda and Decapoda Natantia. ...
Article
AbstractA trial was conducted to evaluate the growth performance and survival of Chelidonichthys lucerna. A total of 13 352 180‐days old juveniles (5.5 ± 2 g; 5 ± 1 cm) were reared at two different densities (A‐EXP = 68 fish m−3; B‐FFA = 15 fish m−3) in eight tanks (four tanks per group) for 360 days. The welfare status and meat quality of fish were evaluated for the A‐EXP and B‐FFA groups in comparison with wild‐caught fishery gurnard (C‐WID). The survival rate was high for both A‐EXP (79%) and B‐FFA (93.5%). B‐FFA fish had the highest specific growth rate (1.16 vs. 1.07; P P P Document Type: Research Article DOI: http://dx.doi.org/10.1111/j.1365-2109.2012.03238.x Publication date: June 1, 2013 $(document).ready(function() { var shortdescription = $(".originaldescription").text().replace(/\\&/g, '&').replace(/\\, '<').replace(/\\>/g, '>').replace(/\\t/g, ' ').replace(/\\n/g, ''); if (shortdescription.length > 350){ shortdescription = "" + shortdescription.substring(0,250) + "... more"; } $(".descriptionitem").prepend(shortdescription); $(".shortdescription a").click(function() { $(".shortdescription").hide(); $(".originaldescription").slideDown(); return false; }); }); Related content In this: publication By this: publisher In this Subject: Aquaculture & Fisheries By this author: Roncarati, Alessandra ; D'Andrea, Mariasilvia ; Pilla, Fabio ; Felici, Alberto ; Melotti, Paolo GA_googleFillSlot("Horizontal_banner_bottom");
... Dans cette dernière région, des études se rapportant à la biologie des différentes espèces de triglidés ont été réalisées dans le bassin oriental, principalement en Grèce et en Turquie où les travaux sur la biologie et l'alimentation ont été effectués par plusieurs auteurs (Papaconstantinou, 1984(Papaconstantinou, , 1986Caragitsou et Papaconstantinou, 1990, 1994Labropoulou et Platis, 1995 ;Labropoulou et Machias, 1998 ;Terrats et al., 2000 ;Icemer et al., 2002 ;Ismen et Ismen, 2004 ;Eryilmaz et Merliç, 2005 ;Ilhan et Tgoulgua, 2007). Les recherches dans le bassin occidental ont été menées particulièrement au niveau de la partie nord (Mouneimne, 1970 ;Kartas, 1971 ;Moreno et Matallanas, 1983 ;Moreno-Amich, 1992 ;Morte et al., 1997 ;Muñoz et al., 2002 ;Colloca et al., 2003). ...
... Cependant, sur les côtes égyptiennes, Faltas (1996) mentionne une augmentation hivernale de l'intensité alimentaire du grondin camard. En outre, Morte et al. (1997), qui ont relevé pendant la période de ponte une réduction du nombre des estomacs vides chez Chelidonichthys lucerna et C. obscurus en Méditerranée occidentale, pensent que les processus physiologiques n'affectent pas le comportement alimentaire de ces espèces de poissons, particulièrement durant la reproduction. ...
Article
Full-text available
La reproduction et le régime alimentaire de Trigloporus lastoviza (Bonnaterre, 1788), espèce de triglidés commune des côtes tunisiennes, ont été étudiés de juin 2007 à mai 2008 dans le golfe de Tunis. Pour l'étude de la reproduction, 688 individus (10,6 cm < Lt < 26 cm) dont 478 femelles et 210 mâles ont été examinés. Le suivi mensuel de l'indice gonadosomatique (IGS) et de la maturité des gonades a montré que la période de maturation a lieu de septembre à décembre et que la ponte débute fin décembre-début janvier. Le suivi mensuel de l'indice hépatosomatique (IHS) met en évidence une augmentation des graisses dans le foie à la même période que la maturation des gonades. Le coefficient de condition (Kc) n'est pas affecté par la maturation des produits génitaux. La taille de première maturité sexuelle (L50) a été estimée à 16,38 cm, 15,65 cm et 15,50 cm pour les mâles, les femelles et les sexes groupés, respectivement. Sur un total de 296 individus examinés pour l'étude alimentaire, près de la moitié (143) présentait un estomac vide. Le coefficient de vacuité (Cv) montre des variations saisonnières significatives. Ce dernier, déterminé chez les juvéniles et les adultes, a montré aussi des différences significatives entre ces deux groupes. L'analyse des contenus stomacaux a permis d'identifier 19 types de proies appartenant à sept phyla (chlorophytes, magnoliophytes, annélides, mollusques, crustacés, bryozoaires et téléostéens). La fréquence d'occurrence (FO), le pourcentage en nombre (Cn), le pourcentage en poids (Cp) et le coefficient alimentaire (Q) des proies ont été calculés. Les crustacés décapodes, proies préférentielles, sont les plus importants numériquement et pondéralement. Ils sont suivis numériquement par les mysidacés et pondéralement par les téléostéens. Le régime alimentaire présente une variabilité saisonnière, celui des juvéniles étant plus diversifié au printemps. Les adultes semblent cibler activement les proies de grande taille. Les juvéniles s'alimenteraient davantage lorsque les ressources sont abondantes.
... In recent years, tub gurnard biology has been studied along northern coasts of the Mediterranean. Most of the available information was provided by Mouneimne (1971) for the Catalan Sea, Papaconstantinou (1984) and Tsimenides et al. (1992) for Greece, Bingel et al. (1993) for the northeastern Mediterranean Sea, Matarrese et al. (1994) for the lonian Sea, Morte et al. (1997) for the Spanish coasts, Ismen and Ismen (2004) for the Bay of Iskendrun (eastern Mediterranean) and Eryilmaz and Meric¸(2005) for the Sea of Marmara. ...
... An increase in the occurrence of empty stomachs in the winter was found for Trigla lyra and Lepidotrigla cavillone on the outer shelf and upper slope of the eastern Mediterranean Papaconstantinou, 1990, 1994). Mediterranean gurnards share a common feeding pattern based on crustaceans and other epibenthic infauna (Colloca et al., 1994;Morte et al., 1997;Labropoulou and Machias, 1998). According to Colloca (1999), tub gurnards change their diet with size. ...
Article
Growth and reproduction of Chelidonichthys lucerna is reported from Tunisian waters. A total of 286 specimens was collected from landings of bottom trawlers between January 2003 and November 2004. The total length ranged from 16 to 36 cm in females and from 17 to 26 cm in males. Marginal increment analysis of otoliths showed that the translucent zone was laid from October to May and the opaque zone laid from June to September. Females were from 0.5 to 9 years and males from 1 to 7 years old. Growth parameters of the von Bertalanffy growth function were TL∞ = 40.26; K = 0.06 and t0 = −3.03 in females and TL∞ = 46.16; K = 0.059 and t0 = −1.32 in males. The coefficient of the allometric length–weight relationships differed significantly by sex. Females with mature gonads were observed between October and May, with peaks in January and February. Length at which 50% of specimens were mature was 21.6 cm TL (estimated age about 3 years) in females and 19.2 cm TL (estimated age about 1.5 years) in males.
... It is therefore apparent that size-related shifts in diet have not been recorded for all gurnard species or may be region specific. Similar to our study, Morte et al. (1997) reported that two gurnard species (Tub Gurnard Chelidonichthys [Trigla] lucerna and Longfin Gurnard) off the coast of Spain (Gulf of Valencia) showed little size-related changes in diet. Similarly, Redbanded Searobins from southeastern Korea showed no size-related change in diet with respect to prey type, but the number of prey items consumed increased with increasing body size (Baeck et al. 2011). ...
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Dietary niches can support the coexistence of closely related sympatric species in marine systems, which can lead to the presence of greater abundances of those species that can potentially support their fisheries or greater abundances for other fish species that prey upon those species. Dietary relationships for three species of gurnard (Family Triglidae) that occur together in the benthic coastal environment of northeastern Tasmania, Australia (Red Gurnard Chelidonichthys kumu, Grooved Gurnard Lepidotrigla modesta, and Roundsnout Gurnard Lepidotrigla mulhalli), were examined for the presence of such dietary niches. The species are either fishery-important (Red Gurnard) or provide prey (Grooved Gurnard and Roundsnout Gurnard) for fishery-important species (e.g., Platycephalidae and Zeidae). Based on stomach content analyses, all three gurnards were shown to be bottom-feeding carnivores that consumed mainly benthic crustaceans, particularly decapods and amphipods, with teleosts also being important in the diets of only the larger Red Gurnard. Nonmetric multidimensional scaling ordination and multivariate analyses based on volumetric contributions of different prey taxa to the stomach contents revealed significant differences in dietary composition among all three species, implying a partitioning of food resources. Size-related and temporal changes in dietary composition were each significant among the three gurnards, but there were no interactions between body size and time. Principal components analysis of head and mouth morphology demonstrated that mouth protrusiveness was the dominant morphological difference among species, which may in part account for the niche partitioning observed from the stomach content analysis. Given the important role of gurnards in benthic food webs, these relationships will improve the specification of ecosystem-based fisheries models and their ability to predict the effects of environmental and anthropogenic perturbations. Received June 29, 2016; accepted April 9, 2017
... Similar diets have been recorded previously for other Triglidae fishes included Trigla lucerna and Aspitrigla obscura in the western Mediterranean (Morte et al., 1997), L. modesta and L. papilio in the south-western Australia (Platell and Potter, 1999), Aspitrigla cuculus, L. cavillone and Trigloporus lastoviza in the eastern Mediterranean (Terrats et al., 2000), C. obscurus and C. lastoviza in Tunisian waters (Boudaya et al., 2007), and Chelidonichthys spinosus and L. guentheri in Korean waters (Huh et al., 2007;Baeck et al., 2011). Triglidae fishes hunt benthic prey by exploring the substratum using six modified pectoral fin rays, which are equipped with chemosensors; a characteristic of gurnard species (Roberts, 1978;Finger, 1982). ...
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Dietary habits and intra- and inter-specific trophic ecology of co-occurring Lepidotrigla mulhalli and L. vanessa from south-eastern Australia were analysed using stomach content and stable isotope ratios (δ¹³C and δ¹⁵N). Both species are bottom-feeding carnivores that consumed mainly benthic crustaceans, but teleosts were also abundant in the diet of larger L. vanessa. Non-metric multidimensional scaling (nMDS) ordination and analysis of similarity (ANOSIM) of dietary data revealed significant inter-specific dietary differences; i.e. food resource partitioning. Carbon (δ¹³C) and nitrogen (δ¹⁵N) stable isotope values were similar between L. mulhalli and L. vanessa, however, suggesting similar trophic positioning. Ontogenetic changes in diet composition and stable isotope values were evident. As L. vanessa grew, they preyed upon larger individuals, such as teleosts and caridean shrmips, but no such trend was observed in the diets of L. mulhalli. Adults of both species were significantly enriched in ¹⁵N relative to juvenile conspecifics thus supporting these data. Consequently, in this study, both methodologies, i.e. stomach content and stable isotope analyses, provided evidence of inter- and/or intra-specific dietary segregations and trophic niche partitioning between co-occurring L. mulhalli and L. vanessa off Tasmanian waters.
... Gary and Ellis (2014) obtained a total of 82 specimens of C. obscurus that were caught in the English Channel, all from 2004 to 2013. To date, little is known about the biology of C. obscurus, and most published data are from the western Mediterranean Sea, where there have been studies of their reproductive biology (Munoz et al., 2003, as Aspitrigla obscura) and feeding habits (Moreno-Amich 1996; Morte et al., 1997;Boudaya et al., 2007) and parasites (Serecca et al., 2013). Genetic analysis should also be conducted on these existent populations to determine their genetic structure as defined for other marine species (Turan, 2006;Turan, 2008). ...
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FULL TEXT LINK: http://nesciences.com/abstract_info.php?page=info&paperID=31 Longfin gurnard Chelidonichthys obscurus (Walbaum, 1792) is reported several times from various researchers in the checklist of Turkish marine fishes. However, last three decades, the species is not occurred in the distributional range, comprising the northeastern Mediterranean Sea and Aegean Sea coast of Turkey. It is possibly critically endangered or absent in the Turkish Seas. Moreover, there has no any biological study been carried out on C. obscurus in Turkey. C. obscurus is considered to be critically endangered or regionally extinct in the eastern Mediterranean Sea and Aegean Sea coast of Turkey. This species might be recorded as “Critically Endangered” in the Mediterranean and Aegean Sea coast of Turkey in the IUCN Red List of Threatened Species.
... This indicates that observed seasonal variations in food ingestion may be related to fluctuations of the prey in the environment. Although no data are available in the study area in relation to the availability of the food supply, previous studies in the Gulf of Valencia on the feeding habits of several fish point out that several prey species, such us L. gracilis, A. glaber, L. depurator, G. rhomboïdes and L. friesii, occurred more frequently in the stomach contents (Vivo & Sanz 1989, Redon et al. 1994Morte et al. 1997, Morte et al. in press). ...
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The stomach contents of 893 specimens of Trachinus draco taken at monthly intervals off the eastern coast of the Gulf of Valencia (Spain), were analyzed to determine diet according to fish size and season. Crustaceans (Mysidacea and Decapoda) and teleosts constituted the main prey. Feeding habits varied with predator size ; small specimens contained a greater number of mysids in their stomachs, while decapods and fishes were more abundant in the stomachs of larger specimens. Little seasonal variation in food habits was noticed.
... The tub gurnard exhibits a particular pattern of migratory movement within its overall depth range during the year; it shows a pronounced concentration the shallow depths in spring and summer and then moves progressively todeeper waters in winter (Ismen and Ismen, 2004). The biological characteristics of tub gurnard was investigated in Mediterranean French coast (Priol, 1932) and (Baron, 1985); Catalan Sea (Mouneimne, 1971); Greece waters (Papaconstantinou, 1984) and (Tsimenides et al., 1992); northeastern Mediterranean Sea (Bingel et al., 1993), (Ismen and Ismen, 2004) and (Cicek et al., 2008); lonian Sea (Matarrese et al., 1994); Egyptian Mediterranean water off Alexandria (Faltas, 1996) and (Faltas and Abdallah, 1997); Spanish coasts (Morte et al., 1997); Sea of Marmara (Eryilmaz and Meric, 2005); Izmir Bay (Uckun and Togulga, 2007, 2005); Gulf of Gabeʼs, Tunisia (Boudaya et al., 2008); Libyan coast (Ahmed, 2012). The present study is proposed to provide information about age, growth, length-weight relationship and reproduction of C. lucerna in the Egyptian Mediterranean waters off Alexandria. ...
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The biology of the tub gurnard, Chelidonichthys lucerna (Linnaeus, 1758), has been studied based on data collected between August (2009) and July (2010) from the Egyptian Mediterranean water in front of Alexandria. A total of 873 specimens ranged between 10.6 and 28.2 cm TL and from 10.2 to 232.5 g total weight, were sampled. The age, growth, length-weight relationship, sex ratio, length and age at first sexual maturity and reproduction period were estimated. Total lengths of males ranged from 12.6 to 23.2 cm and of females from 11.8 to 28.2 cm. The maximum age observed was 4and 5 years for males and females respectively. Length-weight relationships for males and females were estimated as W = 0.0043*L 3.2644 and W = 0.0042*L 3.2651 , respectively indicating an allometric growth. Thevon Bertalanffy growth equations were L t = 29.77(1-e-0.274(t+1.36)) and L t =32.36(1-e-0.255(t+1.09)) for males and females respectively. The growth performance index value (ΦL) was computed as 2.39 for males and 2.44 for females. Length at first sexual maturity was 15 cm (1.21 years) in males and 15.2 cm (1.40 years) in females. The male: femaleratio was 1:1.67. The Gonado-Somatic Index (GSI) values indicated that the spawning season starts from November to February with a peak in January for both sexes.
... Este parámetro es esencial en la determinación de la intensidad de las interacciones interespecíficas en la comunidad (Macpherson, 1981). Estudios de comunidades de peces demersales revelan un incremento del solapamiento de dieta debido a la utilización oportunista de los recursos alimenticios superabundantes (Macpherson, 1981;Targett, 1981;Delbeck & Williams, 1987;Morte et al., 1997Morte et al., , 1999. S. porcus presenta un solapamiento moderado/bajo con las especies más abundantes con que cohabita en el intermareal rocoso. ...
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Scorpaena porcus is distributed in the eastern Atlantic Ocean, from the British Isles to the Azores and Canary Islands, including Morocco, and also the Mediterranean and Black Sea. It inhabits shallow rocky bottoms and using its cryptic coloration lurks around feeding on crustaceans and small fish. It´s captured on many occasions as accessory species, mainly by the artisanal and coastal sector with gill nets or longlines. The present work is the first developed in the rocky intertidal on the Atlantic coast, the rest of the studies have been conducted in Mediterranean areas and using captures from fisheries. It is a stenophagic species which feeding is based on the rocky intertidal in decapod crustaceans and amphipods, also small fish are eaten by larger fish. Although their presence is maintained throughout the year the absence of sexually mature individuals, it´s considerate which uses the rocky intertidal to avoid predation pressure from deeper waters. It presents a positive allometric growth.
... It is important to obtain this information to formulate a balanced diet that includes feedstuffs able to cover metabolic requirements, and provide a quality end product that will be purchased by consumers. The feeding habits of tub gurnard has been investigated, and it has been ascertained that this species exhibits opportunistic foraging behaviour, mainly preying on epibenthic and nectobenthic organisms (Colloca et al., 1994;Morte et al., 1997;Serena et al., 1998;Stagioni et al., 2012) that are rich in essential fatty acids (Dalsgaard et al., 2003). ...
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The quality traits of the fillets from tub gurnard (Chelidonichthys lucerna L.) fished in the mid-Adriatic Sea were investigated. Forty fishes per season were sampled to evaluate the proximate composition, cholesterol content and fatty acid profile of fillets. Seasons significantly affected the quality traits of flesh. The protein content ranged from 19.39% in winter to 19.67% in summer, without significant differences. Lipid content was notably higher in spring (2.28%) and summer (2.32%), compared to autumn (1.72%) and winter (1.31%). Energy content was significantly higher in spring (416.45 kJ/100 g) and summer (417.97 kJ/100 g) compared to autumn (391.35 kJ/100 g) and winter (372.79 kJ/100 g). Saturated fatty acid content was highest in spring (35.88%), whereas monounsaturated acid content was not influenced by season. The n-3 polyunsaturated fatty acid content exceeded 37% of total fatty acid content during summer. The n-6/n-3 ratio remained favourably low across all seasons (from 0.16 to 0.18), with a slight significant increase in autumn (0.31). In conclusion, this study indicates that the flesh of tub gurnard has high nutritional value year-round, with the best results (in terms of n-3 polyunsaturated fatty acids) being obtained in summer.
... Some of the amphipods and copepods such as Longipedia scotti composed the juvenile diet of this species (Tito de Morais and Bodiou, 1984). Th e main predators of the species are john dory (Zeus faber) (Bell and Harmelin, 1983), tub gurnard (Chelidonichthys lucernus) (Morte et al., 1997), rufus snake eel (Ophichthus rufus) (Casadevall et al., 1994), fourspot megrim (Lepidorhombus boscii), and megrim (Lepidorhombus whiffi agonis) (Morte et al., 1999). It is considered a non-commercial species usually remaining in the discarded part of the bottom trawl catch (Machias et al., 2001). ...
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Length distribution, sex ratio, length-weight relationship, age, growth, spawning period, age, and length at first maturity of four-spotted goby inhabiting Izmir Bay were investigated. A total of 1696 four-spotted goby were collected by trawl hauls between July 2004 and June 2007. The size of the fish sampled ranged from 3.1 to 9.2 cm total length. The samples were composed of 31.1% females, 27.7% males, and 41.2% juvenile individuals, with a female to male ratio of 1:0.89. The age of the fish ranged from 1 to 5 years. The length-weight relationship and the von Bertalanffy growth function were estimated for all individuals as: W = 0.0036L(3.45) and L-t = 10.29[1 - e(-0.37t(t + 0.502))]. Spawning period started in February and continued until May. The lengths at first maturity of females and males were 6.15 +/- 0.18 and 6.38 +/- 0.20 cm total length, respectively.
... However, fish also contribute in considerable proportions to the gurnards' diet, becoming for some species a fundamental feeding resource along with ontogenetic development (Colloca et al., 1994; Moreno-Amich, 1994, 1992). Other relevant prey items are molluscs, echinoderms and polychaetes (Morte et al., 1997;Macpherson, 1994; Caragitsou and Papaconstatinou, 1994). Partitioning of resources amongst triglids has been studied in the North-western Atlantic (Ross, 1977), South-western Australia (Platell and Potter, 1999) and the Mediterranean Sea (Labropoulou and Machias, 1998). ...
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The main goals of this dissertation were 1) to test the behaviour of three ecological indicators with holistic characteristics, respectively i) based on network analysis (Ascendency), ii) thermodynamically oriented and often used in ecological modelling (Eco-Exergy and Specific Eco-Exergy) and iii) diversity measures that take into consideration phylogenetic links (Taxonomic Distinctness and associated measures), by the use of empirical data sets, collected in four different ecological scenarios (a gradient of eutrophication symptoms in the south arm of Mondego estuary, Portugal; different hydrodynamic regimes and impacts considering both the south and north arms of Mondego estuary; a recovery process after physical disturbance, from a field experiment carried in the Atlantic rocky shore, Papoa, Portugal, and various types of pollution in the Mar Menor coastal lagoon, Spain) and 2) to appraise the performance of these three ecological indicators in comparison with more conventional and broadly applied ones (e.g. Shannon-Wiener, Margalef and Pielou indices). A brief review of the ecological indicators utilised from the benthic ecological perspective to assess the status of coastal and estuarine ecosystems was done in Chapter 1. This review was carried out aiming at describing how diverse approaches can be, and to put the selected ecological indicators in perspective in the general framework. Chapter 2 dealt with the steps followed to develop mass balanced models of food webs in three areas along a well-documented gradient of eutrophication symptoms in the south arm of the Mondego estuary (Portugal), using the Ecopath with Ecosim software package. The sum of consumptions, exports, respiration, production, flow to detritus, TST and annual rate of net primary production was always higher in the Zostera meadows, followed by the strongly eutrophic area and, finally, by the intermediate eutrophic area. The Ecopath mass balanced models successfully provided a synthesis of the current knowledge of the food web and trophic flows along the gradient of eutrophication symptoms in the Mondego estuary. This tool was particularly important to calculate the network based ecological indicator – Ascendency. In Chapter 3, Ascendency was used as an ecological indicator. Moreover, it was tested whether the network definition of eutrophication properly encompassed changes in community structure observed along the gradient of eutrophication symptoms (Mondego estuary). Pulse eutrophication was considered as the major driving force behind a gradual shift in primary producers from a community dominated by rooted macrophytes to a community dominated by green macroalgae. The measures associated with the intermediate eutrophic area turned out not to be intermediate to those at the gradient extremes. The most likely explanation appears to be the highly unstable nature of this area. Conditions along the spatial gradient were discussed as representing various stages in the temporal evolution of the system, and analysed in the framework of the Intermediate Disturbance Hypothesis, Bifurcation, Chaos, and Catastrophe theories. In Chapter 4, through a re-colonisation field experiment, three main questions were approached regarding the ecological indicators behaviour and the dominant growth forms during the process of recovery. Shannon-Wiener index, Margalef index, Pielou evenness, Eco-Exergy and Specific Eco-Exergy were applied to characterise the state of the community during the process. Results showed that the replacement of species over time occurred, species richness increased rather rapidly and species composition was similar in disturbed and undisturbed areas. Eco-Exergy and Specific Eco-Exergy provided useful information about the structural development of the community. Overall, the characteristics of a systems’ recovery after disturbance appear to be dependent on the spatial scale of the disturbance (openness hypothesis). Finally, in the last chapter (Chapter 5), the robustness of Taxonomic Distinctness measures was tested in different scenarios (estuarine eutrophication, different hydrological regimes, organic and heavy metal pollution, and re-colonisation after physical disturbance), analysing, simultaneously, its correlation with other types of ecological indicators. Results showed that, in most of the case studies, only Total Taxonomic Distinctness was relatively satisfactory in discriminating between disturbed situations. Other Taxonomic Distinctness measures have not proved to be more sensitive than other ecological indicators (Shannon-Wiener, Margalef, and Eco-Exergy indices). Therefore, this approach does not seem to be particularly helpful in assessing systems’ ecological status with regard to the Water Framework Directive implementation. As a final remark, it can be said that the ecological status and development should be evaluated by combining a dynamic battery of useful and efficient indicators, which may provide complementary information.
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A multi-specific approach in fish diet studies provides insight into the complexity of trophic interactions in marine communities. The feeding habits of three gurnard species, Aspitrigla cuculus, Chelidonichthys lucerna and Eutrigla gurnardus (Scorpaeniformes: Triglidae), from the north-middle Adriatic Sea were studied to evaluate prey-resource partitioning amongst species and within species, comparing juveniles’ and adults’ diet for each gurnard species. A total of 1818 specimens (390 A. cuculus, 973 C. lucerna, 455 E. gurnardus) were collected by bottom trawling and they were assigned to size classes (juveniles or adults) on the basis of macroscopic evaluation of the gonads. Stomach contents were analysed. A common dietary preference for Crustacea was found in all species and size classes considered. Nevertheless, gurnards showed distinct feeding behaviour: C. lucerna and E. gurnardus were generalist-opportunistic predators, showing a varied diet based on epi-benthic, bentho-pelagic and necto-benthic preys belonging to different taxa such as Teleostei and Mollusca, while A. cuculus may be considered a specialist feeder, feeding almost exclusively on necto-benthic invertebrates. Morisita’s index calculated for critical size classes (juveniles and adults) pointed out differences. At the inter-specific level, possible dietary competition between A. cuculus and E. gurnardus (C > 0.65) was found for all size classes combined, due to the prey abundance of Lophogaster typicus (Crustacea: Mysida). At the intra-specific level, high diet overlap was found between juveniles and adults of C. cuculus (C = 0.98) and between juveniles and adults of E. gurnardus (C > 0.84). In contrast, C. lucerna did not compete with increasing body size (C < 0.20), showing a clear change from crustaceans to fish in its diet preferences. The possibility that A. cuculus and E. gurnardus may compete for the same prey resources while C. lucerna shows food resource partitioning is discussed. Better understanding of the ecology of these coexisting predators should lead to improved conservation and improved fisheries management.
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Seasonal changes of food habits of the blackwing searobin Prionotus rubio were studied over the continental shelf off Alvarado, Veracruz, Mexico, from Sept. 1994 to Aug. 1995. A total of 234 stomachs (182 with identifiable food) were analyzed. Brown shrimp Farfantopenaeus aztecus, blue crab Portunus sprinicarpus, and rock shrimp Sicyonia dorsalis were the main dietary items. Low values of prey diversity and dietary breadth suggest the main prey were always relatively abundant over the western continental shelf of the Gulf of Mexico. We concluded the blackwing searobin is part of a trophic guild of demersal marine fish that impact mainly on epibenthic invertebrates.
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Records of long-finned gurnard Chelidonichthys obscurus in the western English Channel are rare. Prior to this study, reported incidences were largely restricted to the 19th Century and it appears to have been unrecorded in this well-studied ecosystem over much of the 20th Century. Data from a contemporary trawl survey in and around Lyme Bay (1989–2013) indicate that this species (N = 58) was only present during the period 2005–2013. These data and records from other surveys (N = 24) indicate a localized population may persist in an area just south of Start Point (64–77 m water depth), although it can occasionally occur in shallower inshore waters. A sub-sample of fish was collected to provide additional information on their morphometrics, meristics and diet. Meristic counts were generally in accord with earlier studies as were observations on their diet, which showed that they fed almost exclusively on crustaceans, especially mysids.
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The estimation of fractional trophic levels (TROPHs) is essential for the management of fisheries resources as well as for quantifying the ecosystem effects of fishing. We gathered all available information concerning the feeding habits of 332 fish stocks, belonging to 146 species, 59 families and 21 orders, throughout the Mediterranean Sea, and estimated their TROPH values. The latter ranged from 2.0 to 4.5 and the following functional trophic groups were identified: (a) pure herbivores (TROPH = 2.0–2.1, mean = 2.02, SD = 0.03), which were very rare and represented by Siganus luridus, Siganus rivulatus and Sarpa salpa, all of which feed on red, brown, green and blue-green algae; (b) omnivores with a preference for vegetable material (2.1 Keywords: Mediterranean Sea; feeding habits; fish; fractional trophic levels Document Type: Research Article Affiliations: 1: Aristotle University of Thessaloniki, School of Biology, Department of Zoology, Laboratory of Ichthyology, Box 134, 54006 Thessaloniki, Hellas (Greece) (E-mail: kstergio@bio.auth.gr;Phone: 30310-998268; Fax: 30310-998279) 2: Aristotle University of Thessaloniki, School of Biology, Department of Zoology, Laboratory of Ichthyology, BOX 134, 54006 Thessaloniki, Hellas (Greece);Present address: University of British Columbia, Fisheries Centre, 2204 Main Mall, Vancouver B Publication date: January 1, 2001 $(document).ready(function() { var shortdescription = $(".originaldescription").text().replace(/\\&/g, '&').replace(/\\, '<').replace(/\\>/g, '>').replace(/\\t/g, ' ').replace(/\\n/g, ''); if (shortdescription.length > 350){ shortdescription = "" + shortdescription.substring(0,250) + "... more"; } $(".descriptionitem").prepend(shortdescription); $(".shortdescription a").click(function() { $(".shortdescription").hide(); $(".originaldescription").slideDown(); return false; }); }); Related content In this: publication By this: publisher By this author: Stergiou, K.I. ; Karpouzi, V.S. GA_googleFillSlot("Horizontal_banner_bottom");
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Summary The most common gurnard species in the Gulf of Gabes (Tunisia) are Chelidonichthys lastoviza and C. obscurus. These two species were collected by trawl nets between February 2000 and July 2002 at depths ranging from 80 to 150 meters. In the laboratory the stomach contents were examined for diet assessment and to determine diet variation in relation to fish size, season and sex. The importance of different prey items was analysed utilising several feeding indexes, while diet overlap was tested using Schoener's index and the null model test. The two species showed similar diets, with the same qualitative and quantitative composition. Basic food consisted of crustaceans, mostly mysids and decapods. For Chelidonichthys lastoviza:Gastrosaccus sp. (F = 48.57%), Anchialina agilis (F = 30.57%) and Sicyonia carinata (F = 21.71%); for Chelidonichthys obscurus:Gastrosaccus sp. (F = 80.95%), A. agilis (F = 55.41%) and Pontocaris lacazei (F = 15.15%). A change in food composition based on fish size was observed in both species: mysids more frequently in the diet of small specimens, and decapods in the largest fishes. Seasonal variation in their diet was also recorded. The two fishes showed a significantly higher number of empty stomachs in late autumn and winter. Regardless of species and size class, a biologically significant diet overlap was observed between C. lastoviza and C. obscurus. This result may indicate a lack of competition among triglid species size-class combinations or strong competition that has not yet led to resource portioning.
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Diet overlap calculated as the percentage similarity between the diets of Atlantic cod, Gadus morhua, silver hake, Merluccius bilinearis, and 15 other finfish species was computed from stomach contents data collected in the northwest Atlantic between Cape Hatteras, North Carolina, U.S.A., and western Nova Scotia, Canada, from 1973 through 1976. Since crustaceans are preyed on by both Atlantic cod and silver hake and most of the 15 other groundfish species representing members of the Rajiformes, Perciformes, Gadiformes, and Pleuronectiformes, completely dissimilar diets occur very rarely. Although the overlap values are quite variable, the greatest overlap, with few excep­ tions, occurs amongthe gadiform fishes themselves rather than between the gadids and species from the three other ordinal taxonomic levels, Furthermore. Atlantic cod and silver hake show a size dependent shift in diet (at 60-70 cm for Atlantic cod and 20-25 cm for silver hake) from crustaceans to fish so that, generally, the major overlap levels are for the smaller size classes of fish, Overlap levels are discussed in relation to the prey species the predators share and also in terms of their usefulness in identifying potential trophic linkages between northwest Atlantic finfish. The traditional way of identifying fish is by recognizing individual species as discrete taxo­ nomic units. Although the species concept is fun­ damental to any biological work, fishery biolo­ gists have been considering other means of grouping species. These are usually attempts to lump species in an ecological sense and they often depend on the fishes' diet. These feeding niche groupings may then be related to the morphol­ ogy and size of the fish or the prey. Food related size classes for fish have, for example, been iden­
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Sympatric native Anolis species with similar structural habitats but contrasting climatic habitats are closer in head and body size on species-rich than on depauperate islands. In two localities, sympatric Anolis species with differential occurrences in sun or shade sought lower, more shaded perches during midday, resulting in partly nonsynchronous utilization of the vegetation by the two species. The second observation may be related to the first in the following way: nonsynchronous spatial overlap could dictate relatively great resource overlap for species coinhabiting patchy or edge areas, requiring great differences between the species in prey size in addition to those in climatic habitat. The extent of such overlap on small depauperate islands could be greater if these contained a greater proportion of patchy or edge habitats (with respect to insolation), or if climatic preferences were broader and more overlapping than on large, species-rich islands. In each locality, the relatively more shade-inhabiting species occurred more often on larger perches and on lower perches than did the other species. In both species of the Bermudan pair, adult males occupied higher and larger perches, and in grahami, shadier perches, than did female-sized individuals. The statistical significance of these and other differences was evaluated using several unweighted @g^2 procedures, Cochran's weighted @g^2 test and a partitioning technique for analyzing interactions among variables in complex contingency tables. The last method is described in detail in the papaer by Fienberg, immediately following this one.
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Methods for analysing fish stomach contents are listed and critically assessed with a view to their suitability for determining dietary importance—this term is defined. Difficulties in the application of these methods are discussed and, where appropriate, alternative approaches proposed. Modifications which have practical value are also considered. The necessity of linking measurements of dietary importance to stomach capacity is emphasized and the effects of differential digestion upon interpretation of stomach contents outlined. The best measure of dietary importance is proposed as one where both the amount and bulk of a food category are recorded.
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Dietary components of Mississippi silversides (Menidia audens) and juvenile largemouth bass (Micropterus salmoides) were tabulated by the percentage of occurrence, the percentage of total number, the percentage of total volume, the average of the volume percentages, and the relative importance index. Each of these diet measures was then applied to three published overlap indexes and a correlation method (Spearman rank correlation coefficient). Each measure of diet resulted in different values for a particular overlap index (0.04 to 1.06) and for the Spearman rank correlation coefficient (0.06 to −0.30). Likewise, each index gave different values for different diet measures. Of these indexes and diet measures, the Schoener index based on the average of volume percentages is recommended with reservations.
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The stomach contents of the five species were analysed with respect to frequencies, average numbers, and average weights of the food taxa. The food of G. a. thori, which was studied thoroughly for the first time, was dominated by euphausiaceans (mostly by Meganyctiphanes norvegica) copepods, and mysidaceans. In each of the other four species, the most important groups of animals in the food were the same as those found in previous studies. In T. esmarkii, R. cimbrius, and G. cynoglossus a positive correlation was found between the optimal lengths of the fish with respect to the proportions (by number) of the numerically dominant food species, and the sizes of these food species. Information on the vertical ranges of the food species with the highest frequencies was used to deduce the relative positions of the horizontal zones used for feeding by the fish species. G. cynoglossus mostly took its food on the bottom, R. cimbrius just above the bottom, T. esmarkii on a higher level, and G. a. thori on...
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IN the waters off Plymouth there exists a definite inshore fishing-ground, approximately 13 square miles in area, locally known as the “corner.” In order to obtain some idea of the Bionomic conditions prevailing on this ground an intensive study of the bottom fauna was undertaken. Quantitative seasonal observations extending over a period of one year (August, 1928–July, 1929 inclusive) have been made, using the 0.1 square metre Bottom Sampler and the “Agassiz” Trawl, a method having been devised for obtaining quantitative hauls with the latter instrument. Investigations into the food actually eaten by the fishes within the area have been carried on simultaneously, and the stomach contents of over 2000 fishes comprising 29 different species have been examined. On account of the length of time required for stomach examination, it was found impossible to make seasonal observations on them also, but comparable winter and summer examinations were made.
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The composition of the diet of Citharus linguatula (L.) off the coast of the Gulf of Valencia, Spain, was determined between October 1989 and October 1990. The percentage of empty stomachs remained constant throughout the year, except for the period August to September, when a maximum was recorded coinciding with the reproductive period. Crustaceans (Mysidacea and Decapoda) and teleosts constituted the main prey. The composition of the prey ingested varied with predator size; small specimens contained a greater number of mysids in their stomachs, while decapods and fishes were more abundant in the stomachs of larger specimens. Diets varied seasonally: mysids were more important during autumn, whereas decapods were more important during winter and spring. Fishes were numerically most important in the diet in summer, but the frequency of occurrence was constant throughout the year.
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The burrows of the Norway lobster Nephrops norvegicus (L.) and of the crab Goneplax rhomboides (L.) were studied in Loch Torridon, Scotland. Polyester resin casts of burrows in the sea were made by divers to reveal their subsurface form. Tunnels made by N. norvegicus were usually simple, with two or more openings on the mud surface, and penetrated to a depth of about 30 cm. G. rhomboides burrows did not descend more than about 15 cm beneath the surface, but were usually more complex than the lobster burrows and had several openings. The methods of burrow construction used by the two crustaceans are described from aquarium observations. Neither N. norvegicus nor G. rhomboides show obvious morphological adaptations for burrowing, and it is suggested that the fossorial habit was adopted very early by decapods. The burrows of N. norvegicus do not seem to have assumed any functions in addition to the original one of providing refuge from predators. There is not sufficient known of the biology of the crab to indicate whether the same is true in its case.
Ecología trófica en la costa catalana y morfología alimentaria de la familia triglidae (Pisces: Scorpaeniformes)
  • R Moreno-Amich
Contributi alla biologia degli stadi giovanili di Trigla lucerna (Pisces, Scorpaeniformes)
  • Serangeli