Latest Articles from Zoologia Latest 6 Articles from Zoologia https://zoologia.pensoft.net/ Fri, 29 Mar 2024 10:23:51 +0200 Pensoft FeedCreator https://zoologia.pensoft.net/i/logo.jpg Latest Articles from Zoologia https://zoologia.pensoft.net/ Age, growth and reproductive biology of two endemic demersal bycatch elasmobranchs: Trygonorrhina fasciata and Dentiraja australis (Chondrichthyes: Rhinopristiformes, Rajiformes) from Eastern Australia https://zoologia.pensoft.net/article/49318/ Zoologia 37: 1-12

DOI: 10.3897/zoologia.37.e49318

Authors: Marcelo Reis, Will F. Figueira

Abstract: Bottom-dwelling elasmobranchs, such as guitarfishes, skates and stingrays are highly susceptible species to bycatch due to the overlap between their distribution and area of fishing operations. Catch data for this group is also often merged in generic categories preventing species-specific assessments. Along the east coast of Australia, the Eastern Fiddler Ray, Trygonorrhina fasciata (Muller & Henle, 1841), and the Sydney Skate, Dentiraja australis (Macleay, 1884), are common components of bycatch yet there is little information about their age, growth and reproductive timing, making impact assessment difficult. In this study the age and growth (from vertebral bands) as well as reproductive parameters of these two species are estimated and reported based on 171 specimens of Eastern Fiddler Rays (100 females and 71 males) and 81 Sydney Skates (47 females and 34 males). Based on von Bertalanffy growth curve fits, Eastern Fiddler Rays grew to larger sizes than Sydney Skate but did so more slowly (ray: L∞ = 109.61, t0 = 0.26 and K = 0.20; skate: L∞ = 51.95, t0 = -0.99 and K = 0.34 [both sexes combined]). Both species had higher liver weight ratios (HSI) during austral summer. Gonadal weight ratios (GSI) were higher in the austral winter for Eastern Fiddler and in the austral spring for Sydney Skates.

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Research Article Thu, 17 Dec 2020 20:52:33 +0200
Analysis of reproductive biology and spawning season of the pink ear emperor Lethrinus lentjan, from marine ecosystem https://zoologia.pensoft.net/article/48475/ Zoologia 37: 1-10

DOI: 10.3897/zoologia.37.e48475

Authors: Elsayed M. Younis, Nasser A. Al-Asgah, Abdel-Wahab A. Abdel-Warith, Mohamed H. Gabr, Fozi S. Shamlol

Abstract: A total of 593 samples of Lethrinus lentjan (Lacepede, 1802) were collected from the Red Sea, Jeddah, Saudi Arabia, to study their productive biology and spawning season of the local population. Sampling was carried out on a monthly basis for a period of one year. The monthly sex ratios indicated that females were dominant throughout the study period, with an overall male:female sex ratio of 1:7.98, although males were larger than females. The highest monthly performance maturation index (PMI), as well as the male and female gonadosomatic index (GSI) and ovarian maturation rate (OMR) were observed in February and March. Histological examination of the gonads confirmed the process of sexual transformation in this fish species, wherein individuals mature first as female, and then change sex to male (protogynous hermaphroditism). Histological sections also showed that the sexual maturation of males of L. lenjtan comprised three main stages, while the sexual development of females could be classified into four main stages. Extended spawning in the form of batches released during different months throughout the year were recorded for this fish species, with the main spawning season in February and March, and an additional, shorter spawning season in September.

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Research Article Mon, 11 May 2020 10:29:36 +0300
Actual status of fishing reserves of the Yesil River https://zoologia.pensoft.net/article/30437/ Zoologia 36: 1-9

DOI: 10.3897/zoologia.36.e30437

Authors: Zhumagazy Kurzhykayev, Kuanysh Syzdykov, Ainur Assylbekova, Dinara Sabdinova, Viktor Fefelov

Abstract: In this article, the study and prediction of the state of fish resources in the Yesil River was carried out to determine the boundary reference points of the reserve and management decisions in case they are exceeded, to ensure sustainable fisheries and preserve biological diversity. Ichthyological studies, retrospective analyses and rankings of the effects of the water supply of the Yesil River on fish stocks have been carried out, critical values ​​of the biomass of fishing reserves have been determined, as criteria for biologically safe fishing values and targets for management of fish stocks at reaching the boundary values ​​of 24.03 tonnes have been established. According to the results of studies of basic biological indicators, it was determined that roach, bream, pike and perch populations each had an LC50 above LM50, which indicates their low utilization in the fishery industry. A strategy for management of fish stocks, recommendations for the conservation of fishery resources and their rational use has been developed as a result of these findings. The list and status of the monitored indicators for the careful management of fish stocks, as well as a list and indicators of the boundary indicators for the state of fish stocks, was established. These parameters included the fish size of 50% of the sampled fish and 50% of maturity achieved, where the LC50 was observed in the fish in question from 19 to 45.4 cm and LM50 from 12.3 to 41 cm, respectively. The minimum and maximum river levels that ranged from 111 up to 159 cm, as well as the critical value of the commercial reserve, corresponded to the boundary value of 24.03 tonnes. The results of this work will serve as the basis for making future managerial decisions, necessary for sustainable fisheries and conservation of the biological diversity of the Yesil River.

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Research Article Thu, 3 Oct 2019 02:10:50 +0300
Length-based estimates of growth parameters and mortality rates of fish populations from a coastal zone in the Southeastern Brazil https://zoologia.pensoft.net/article/22235/ Zoologia 35: 1-8

DOI: 10.3897/zoologia.35.e22235

Authors: Marcus Rodrigues da Costa, Rafael de Almeida Tubino, Cassiano Monteiro-Neto

Abstract: Small-scale fisheries in Brazil contribute to a significant share of total fish production, accessing a large variety of species. Life history parameters from these resources are important for their management and conservation, based on primary data. The objective of this article is to generate growth parameters and mortality rates of ten fish populations from a coastal zone in Southeastern Brazil. Monthly samples were taken between January 2011 and November 2014 from landings of the beach-seine fishery in an area adjacent to the entrance of the Guanabara Bay. All fishes were measured (total length) and weighed. The length-weight relationships (LWR) were estimated by linear regression analysis on log-transformed data of the equation: W = aLb. The Von Bertalanffy Growth Function (VBGF) was fitted to size-at-age data to obtain growth parameters (K, L∞). The length-converted catch curve was used for estimating the instantaneous total mortality (Z). Taylor’s equations provided an independent estimate of the natural mortality (M) and longevity. The difference between Z and M derived Fishing mortality (F). A total of 2,938 individuals from ten fish species were used to determine the length-weight relationships. Harengula clupeola (Cuvier, 1829) has a new maximum length record for the FishBase LWR database. Sardinella brasiliensis (Steindachner, 1879) presented the smallest and largest size recorded for LWR observed in the literature and FishBase database. Upeneus parvus showed the greatest total length, while Trichiurus lepturus Linnaeus, 1758, Orthopristis ruber (Cuvier, 1830) and Dactylopterus volitans (Linnaeus, 1758) presented the smallest sizes for LWR in FishBase. The other species showed parameters within the expected values for each group. The performance index combining information from K and L∞ presented values between 2.32 and 3.76 and were considered appropriate for the populations evaluated. Fishing was the primary source of mortality for Caranx crysos (Mitchill, 1815), Eucinostomus argenteus Baird & Girard, 1855, S. brasiliensis and U. parvus, and less important for Cynoscion jamaicensis (Vaillant & Bocourt, 1883), D. volitans, O. ruber, Selene setapinnis (Mitchill, 1815), T. lepturus and H. clupeola. The parameters generated may be used for the management and conservation of the species’ stocks.

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Research Article Fri, 23 Nov 2018 21:35:22 +0200
Morphological study of the gastrointestinal tract of Larimichthys crocea (Acanthopterygii: Perciformes) https://zoologia.pensoft.net/article/25171/ Zoologia 35: 1-9

DOI: 10.3897/zoologia.35.e25171

Authors: Hameeda Kalhoro, Shengli Tong, Lei Wang, Ying Hua, Josie Ancella Volatiana, Qingjun Shao

Abstract: The present study aimed to investigate the macroscopic and histological structure of the gastrointestinal tract (GIT) of Larimichthys crocea (Richardson, 1846). It consists of esophagus, stomach regions, pyloric caeca, intestinal regions, and rectum. Sixteen tubular light yellowish pyloric caeca of similar sizes were observed in all individuals. The digestive wall consists of mucosa, submucosa, muscularis, and adventitia. No major differences appeared in the structure of the tunica, epithelial cell types, connective tissues and musculature glands of L. crocea GIT. The mucosal epithelia in the oesophagus has longitudinal branched folds with frontward and hindmost zones. The gastric tunica mucosa has a characteristic folded structure and can be divided into three regions. The intestinal tunica mucosa is characterized by villi structures and numerous mucus-secreting cells. Mucus-secreting goblet cells were strongly positive to AB at pH 2.5 in the oesophagus (excluding gastro-oesophageal junction) and intestine mucosal regions, which indicates an abundance of carboxylate mucins. The surface epithelia of the gastric mucosa is PAS-positive and AB-negative. SEM examination revealed that cells in the epithelium of the esophagus have an unbroken apical layer and goblet cells. The intestinal coefficient (IC) of L. crocea was 0.80 ± 0.21, consistent with a carnivorous or omnivorous habit. Our study adds the knowledge of the digestive system of L. crocea and might be useful in the management of L. crocea stocks.

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Research Article Thu, 1 Nov 2018 06:29:16 +0200
Composition of gastrointestinal content, protease and lipase activities in summer and winter of four freshwater siluriforms (Teleostei: Actinopterygii) with two different feeding habits https://zoologia.pensoft.net/article/13286/ Zoologia 35: 1-8

DOI: 10.3897/zoologia.35.e13286

Authors: Ana Paula Gottlieb Almeida, Everton Luis Zardo, Candida Toni, Everton Rodolfo Behr, Leila Picolli da Silva, João Paes Vieira, Vania Lúcia Loro, Bernardo Baldisserotto

Abstract: The aim of this study was to determine the composition of gastrointestinal content and protease and lipase activities in summer and winter as well as to evaluate the relationship between digestive enzyme activity and centesimal composition of gastrointestinal content and feeding habits of two omnivorous species, Rhamdia quelen (Quoy & Gaimard, 1824) and Pimelodus maculatus (LaCèpede, 1803), and of two detritivorous species, Loricariichthys anus (Valenciennes, 1835) and Hypostomus commersoni (Valenciennes, 1836). The activities of pepsin, trypsin, chymotrypsin, and lipase, and the levels of proteins and lipids in the gastrointestinal tract, were evaluated. The enzyme activities were not related to the centesimal composition of gastrointestinal content or feeding habits. This finding could be associated with the variations of nutrient availability over time in the environment, as was observed in the centesimal composition of food ingested by the fish in summer and winter. The analyzed enzymes exhibited a constitutive character in these species; that is, the digestive enzymes are always available in the gastrointestinal tract to digest any food that the fish may find as an adaptation to better utilize the nutrients available in the environment in winter and summer.

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Research Article Wed, 23 May 2018 23:55:20 +0300