scholarly journals Biological and Ecological Aspects of the Blackmouth Catshark (Galeus melastomus Rafinesque, 1810) in the Southern Tyrrhenian Sea

2021 ◽  
Vol 9 (9) ◽  
pp. 967
Author(s):  
Claudio D’Iglio ◽  
Marco Albano ◽  
Francesco Tiralongo ◽  
Sergio Famulari ◽  
Paola Rinelli ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Sexual Maturity ◽  
Environmental Changes ◽  
Feeding Habits ◽  
Stomach Content Analysis ◽  
Tyrrhenian Sea ◽  
Ecological Aspects ◽  
Size At Sexual Maturity ◽  
Southern Tyrrhenian Sea ◽  
Index Value

Data on the biology and ecology of Galeus melastomus are old/absent for the Southern Tyrrhenian Sea, despite there being numerous studies in the wider area. A total of 127 specimens of G. melastomus from the southern Tyrrhenian Sea, collected in 2018–2019 using trawling nets, were analyzed to investigate size at sexual maturity, sex ratio, length–weight relationships, and feeding habits. To our best knowledge, this is the first time in which all these features were investigated in the Southern Tyrrhenian Sea for G. melastomus. The stomach content analysis showed that G. melastomus had intermediate feeding habits, preying on a great variety of species, especially Cephalopoda, Osteichthyes, and Crustacea. The Levin’s index value (Bi) was 0.53. Sex ratio was 0.92:1, with females slightly more abundant and bigger than males. The results also showed a decrease (33.7 cm for females, 31.1 cm for males) in length at 50% maturity (L50). This could be a result of anthropogenic stressors, such as overfishing and/or and environmental changes, which can induce physiological responses in several species. Our results highlighted the differences related to sexual maturity, growth, and feeding habits of the blackmouth catshark in the studied area, providing reference data to allow comparison with future studies on this species adaptations to this and other deep-sea areas in the Mediterranean Sea.

scholarly journals Seasonal variations in the population biology of Salmostoma bacaila (Cyprinidae) from a tributary of the Payra River, Bangladesh

2019 ◽  
pp. 113-119
Author(s):  
Ahamed Ahamed ◽  
Faruque Ahmed Zoarder ◽  
Jun Ohtomi
Keyword(s):  
Sex Ratio ◽  
Seasonal Variations ◽  
Population Biology ◽  
Sexual Maturity ◽  
Condition Factor ◽  
Gonadosomatic Index ◽  
Spawning Season ◽  
Frequency Distributions ◽  
Size At Sexual Maturity ◽  
Management And Conservation

Some biological parameters of Salmostoma bacaila – including sex ratio, length-frequency distributions (LFDs), size at sexual maturity, spawning season, length-weight relationships (LWRs) and condition factor – were studied. Samples were collected seasonally during June 2017 to May 2018 from a tributary of the Payra River. The overall sex ratio was significantly different from the expected value of 1:1 (p < 0.001), in favour of male specimens. Females were significantly larger than males. Size at sexual maturity was estimated at 7.6~7.7 cm total length. Seasonal variations in the gonadosomatic index (GSI) indicate that the main spawning season is from spring to summer. The LWRs showed negative allometric growth in both sexes, but with clear seasonal variation. Fulton’s condition factor varied in both sexes and was attributed to variations in GSI with maturity. The fin¬dings of this study will be helpful for management and conservation of S. bacaila populations.

Food and feeding habits of pearly razorfish, Xyrichtys novacula (Linnaeus, 1758), in the southern Tyrrhenian Sea: variation by sex and size

2005 ◽  
Vol 72 (2) ◽  
pp. 123-133 ◽  
Author(s):  
Luca Castriota ◽  
Maria Pia Scarabello ◽  
Maria Grazia Finoia ◽  
Mauro Sinopoli ◽  
Franco Andaloro
Keyword(s):  
Feeding Habits ◽  
Tyrrhenian Sea ◽  
Food And Feeding ◽  
Southern Tyrrhenian Sea

scholarly journals Population structure and reproductive cycle of the commercial sea cucumber Holothuria mexicana in Belize

2018 ◽  
Vol 66 (4) ◽  
Author(s):  
Arlenie Rogers ◽  
Jean-François Hamel ◽  
Annie Mercier
Keyword(s):  
Sex Ratio ◽  
Protected Areas ◽  
Reproductive Cycle ◽  
Sexual Maturity ◽  
Sea Cucumber ◽  
Size Structure ◽  
Natural Populations ◽  
Gonad Index ◽  
Size At Sexual Maturity ◽  
Spawning Periods

The population and reproductive biology of the commercial sea cucumber Holothuria mexicana (Ludwig, 1875) was studied in Southern Belize (Caribbean Sea), including the sex ratio, size at sexual maturity and reproductive cycle, as well as the size structure among habitats located inside and outside protected areas. Individuals found inside marine protected areas were consistently larger than individuals found outside these boundaries. The male:female sex ratio was 1.1:1.0 with a unimodal size distribution composed mainly of sexually mature individuals (87 %). Size at sexual maturity was established to be ~10 cm based on measures of gamogenetically mature individuals during the peak of the gametogenic maturity period. Juveniles and small adults measuring ≤ 15 cm (13 %), were collected exclusively in sandy and muddy areas of seagrass habitats associated with mangroves. Larger adults were commonly found on hard substrates in both seagrass-associated and coral-reef-associated habitats. Based on histology and gonad indices, the first sign of early gametogenesis was detected in August in both sexes. Gametes developed and matured throughout the colder months between November and February. Decreases in gonad index in both years suggest annual spawning, starting in March-April 2014 (single major event) and March-April and July-August 2015 (two smaller events) for both males and females. The spawning periods were correlated with warmer or increasing temperatures, low rainfall and increasing or high chlorophyll-a concentrations. These data will hopefully guide management and protection of the natural populations of H. mexicana, which are already suffering from overfishing in Belize and neighboring countries. 

Feeding habits and selectivity of the wide-eyed flounder,Bothus podas(Delaroche, 1809) (Bothidae) from the southern Tyrrhenian sea

2010 ◽  
Vol 6 (5) ◽  
pp. 496-502 ◽  
Author(s):  
Valentina Esposito ◽  
Luca Castriota ◽  
Pierpaolo Consoli ◽  
Teresa Romeo ◽  
Manuela Falautano ◽  
...  
Keyword(s):  
Feeding Habits ◽  
Tyrrhenian Sea ◽  
Southern Tyrrhenian Sea

scholarly journals Population biology of Uca mordax (Smith, 1870) (Crustacea, Decapoda, Ocypodidae) from the southeastern coast of Brazil

2009 ◽  
Vol 31 (73/75) ◽  
Author(s):  
Vivian Fransozo ◽  
Rafael Campanelli Mortari ◽  
Aline Staskowian Benetti
Keyword(s):  
Sex Ratio ◽  
Population Biology ◽  
Sexual Maturity ◽  
Fiddler Crab ◽  
Carapace Width ◽  
Southeastern Coast ◽  
Size Classes ◽  
Median Size ◽  
Size At Sexual Maturity ◽  
Males And Females

The population biology of the fiddler crab Uca mordax (Smith, 1870) was investigated in an estuarinemangrove from the southeastern coast of Brazil. Samplings were monthly performed by 2 collectors for30 min. using the technique of capture per unit effort during low tide periods. The allometric techniquewas used to determine crab size at sexual maturity (males and females). Thus, specimens were classified into juveniles and adults according to their size at sexual maturity for each sex. The specimens weredistributed into size classes. Recruitment was based on the juvenile frequency and the reproduction peakin ovigerous females. The median size of males was 15.9 ± 2.7 mm carapace width (CW) (n = 557) andthat of females, 14.6 ± 2.8 mm CW (n = 528). At sexual maturity, size of crabs was 11.9 mm CW formales and 11.5 mm CW for females. Juveniles were found throughout the year but more frequently inthe winter and autumn. Sex ratio did not differ among seasons, except during the summer (p < 0.05).As regards sex ratio per size class, females predominated in the fi rst size classes. Reproduction peakwas observed in the summer. In short, the population biology of U. mordax was similar to that of mostbroad-front fi ddler crab species.

Some Reproductive Aspects of Latreutes Fucorum (Fabricius, 1798) (Decapoda, Hippolytidae) from Bahía De La Ascensión, Quintana Roo, Mexico

Crustaceana ◽  
2011 ◽  
Vol 84 (11) ◽  
pp. 1353-1365 ◽  
Author(s):  
Mario Martínez-Mayén ◽  
Ramiro Román-Contreras
Keyword(s):  
Sex Ratio ◽  
Sexual Maturity ◽  
Atlantic Coast ◽  
Quintana Roo ◽  
Egg Volume ◽  
Reproductive Characteristics ◽  
Stage Of Development ◽  
Average Fecundity ◽  
Size At Sexual Maturity ◽  
Size Interval

Abstract Latreutes fucorum (Fabricius, 1798) has a distribution that includes the American Atlantic coast from Canada to Brazil and part of the Antilles, as well as the Azores Islands and Cape Verde in the eastern Atlantic; however, there is little published information on the reproduction of this species. The aim of this study is to provide data on some reproductive characteristics of L. fucorum as fecundity, egg volume, sex ratio, and size at sexual maturity (CL50). The shrimps were collected on Thalassia testudinum Banks & Solander ex König meadows in Bahía de la Ascensión, Quintana Roo, Mexico during May 2002 by means of a Coleman-Seagrove sledge net with 800 μm mesh opening. We analysed 1097 specimens, from which was obtained a sex ratio of 1.59 males per female. The size interval of ovigerous females was 1.80 to 3.88 mm cephalothoracic length (CL), and we estimated a size at sexual maturity in the population of 2.55 ± 0.79 mm CL. Average fecundity was 96.25 ± 53.16, with 25 eggs as minimum and a maximum of 323, with a correlation coefficient of 0.72 between cephalothorax length and fecundity. Average egg volume varied from 0.013 mm3 in the first stage of development to 0.025 mm3 in embryos near hatching, which represents an increase of 92.3%. This is the first study about reproductive characteristics of L. fucorum for the Atlantic coast of Mexico.

Feeding habits of the Atlantic bonito, Sarda sarda (Bloch, 1793) in the southern Tyrrhenian sea

2006 ◽  
Vol 81 (2-3) ◽  
pp. 169-175 ◽  
Author(s):  
D. Campo ◽  
E. Mostarda ◽  
L. Castriota ◽  
M.P. Scarabello ◽  
F. Andaloro
Keyword(s):  
Feeding Habits ◽  
Tyrrhenian Sea ◽  
Southern Tyrrhenian Sea ◽  
Sarda Sarda

scholarly journals Ecological Aspects of a Wood Turtle, Glyptemys insculpta, Population at the Northern Limit of its Range in Québec

2003 ◽  
Vol 117 (3) ◽  
pp. 377 ◽  
Author(s):  
Andrew D. Walde ◽  
J. Roger Bider ◽  
Claude Daigle ◽  
Denis Masse ◽  
Jean-Claude Bourgeois ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Carapace Length ◽  
Feeding Habits ◽  
High Rate ◽  
Activity Period ◽  
Northern Limit ◽  
Glyptemys Insculpta ◽  
Research Initiative ◽  
Ecological Aspects ◽  
Wood Turtles

As part of a conservation research initiative, a population of Wood Turtles (Glyptemys insculpta) at the northern limit of its range was studied to ascertain characteristics of its demographics, morphometrics, density, mortality, feeding, and mating activities. Turtles were captured and marked during the activity period in 1996 and 1997. In addition, 20 individuals were radio-tracked weekly. A total of 188 turtles was captured and the size of the population in the study area was estimated at 238 turtles. The estimated population density based on this calculation is 0.44 turtles/ha. This is less than other studies indicating that population densities are greater in southern populations. Turtles from this population were large (carapace length of males=214.5 ± 4.21 mm, females=201.1 ± 10.88 mm) which supports the hypothesis that turtle size is negatively correlated with number of frost free days. The sex ratio was not significantly different from 1:1. Juvenile turtles accounted for 31.4% of the population. Observations of feeding habits support the claim that Wood Turtles are opportunistic omnivores. Of the 35 mating or courtship events observed, 77 % occurred in the fall and half of them between 11:00 and 13:00. Although limb and tail injuries and parasites were observed on many turtles, no dead turtles were observed. This last result, combined with the high rate of recruitment and even sex ratio suggests that this population is stable, making it an ideal population with which to make comparisons with other studies in areas where the species could be in decline.

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