DOI: 10.3897/zoologia.38.e53756

Authors: Geysa Marinho de Souza, Cassiano Monteiro-Neto, Marcus Rodrigues da Costa, Ana Luiza Bastos, Raquel Rennó Mascarenhas Martins, Francyne Carolina dos Santos Vieira, Magda Fernandes de Andrade-Tubino, Rafael de Almeida Tubino

Abstract: The bluefish, Pomatomus saltatrix (Linneus 1766) is captured by industrial, artisanal, and recreational fisheries throughout its distribution range. The reproductive biology of P. saltatrix in the southwestern Atlantic was studied using 1,102 specimens captured by the Brazilian commercial fleet between March 2014 and December 2015. The recruitment period was identified from records of juveniles in experimental beach seine hauls carried out on sandy beaches in the external sector of Guanabara Bay for four years (2012–2015). Based on the reproductive indices and on the macro- and microscopic analyses of the gonads, spawning peaks were identified in autumn and spring. The size at first maturity was estimated at 35.5, 38.3, and 37.4 cm for females, males, and general, respectively. Ovary analyses and measurements of the oocyte diameters indicated that bluefish are multiple spawners with asynchronous oocyte development. The batch fecundity estimate was 202,752.5 eggs and ranged from 9,800.9 to 426,787.0 eggs. The species reproduces throughout the entire study area, but it is more active in the south of Arraial do Cabo. The young-of-the-year were recorded on shallow water in all seasons, with modal peaks in the summer months. The parameters estimated in this study expand and update information on this species, providing important data for the evaluation and fisheries management of the stock of P. saltatrix in the southwestern Atlantic.

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DOI: 10.3897/zoologia.37.e51043

Authors: Grace E. Okuthe, Bongile Bhomela

Abstract: This study described anatomical, histological and histochemical features of the mucosal layer of the digestive tract of Tilapia sparrmanii Smith, 1840, an omnivorous freshwater fish endemic to Southern Africa. This species exhibited a short thick oesophagus with long deep longitudinal folds (466.68 ± 16.91 µm), and a thick (173.50 ± 10.92 µm) muscular layer that allow the passage of large food items. The mucosa was lined with stratified secretory epithelium rich in goblet cells that secreted neutral and acid mucins. The stomach was a sac-like structure with simple tubular glands surrounded by connective tissue. The mucosa was lined with simple columnar epithelium and the lamina propria exhibited a well-developed layer of gastric glands that occupied the entire length of the cardio-fundic region. The stomach mucosa consisted of epithelial cells with intense neutral mucin secretion which protects against gastric juice. Neck cells of gastric glands synthesized neutral and acid mucins. The intestine was highly coiled and presented a complex pattern of transversal folds internally (villi). Villi length decreased progressively from the anterior to the posterior intestine (p < 0.0001). Tunica muscularis of the mid-intestine had the thinnest thickness among all parts of the intestine (p < 0.0001). Goblet cells whose numbers increased towards the rectum secreted both acid and neutral mucins. The results indicate structural similarities of T. sparrmanii GIT with other tilapia species and will be useful for understanding the physiology of the digestive systems as well as functional components of the GIT.

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DOI: 10.3897/zoologia.37.e49046

Authors: Jie Gong, Baohua Chen, Bijun Li, Zhixiong Zhou, Yue Shi, Qiaozhen Ke, Dianchang Zhang, Peng Xu

Abstract: The whole mitochondrial genome of Lateolabrax maculatus (Cuvier, 1828) was used to investigate the reasons for the observed patterns of genetic differentiation among 12 populations in northern and southern China. The haplotype diversity and nucleotide diversity of L. maculatus were 0.998 and 0.00169, respectively. Pairwise FST values between populations ranged from 0.001 to 0.429, correlating positively with geographic distance. Genetic structure analysis and haplotype network analysis indicated that these populations were split into two groups, in agreement with geographic segregation and environment. Tajima’s D values, Fu’s Fs tests and Bayesian skyline plot (BSP) indicated that a demographic expansion event may have occurred in the history of L. maculatus. Through selection pressure analysis, we found evidence of significant negative selection at the ATP6, ND3, Cytb, COX3, COX2 and COX1 genes. In our hypotheses, this study implied that demographic events and selection of local environmental conditions, including temperature, are responsible for population divergence. These findings are a step forward toward the understanding of the genetic basis of differentiation and adaptation, as well as conservation of L. maculatus.

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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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DOI: 10.3897/zoologia.36.e38455

Authors: Germán Augusto Murrieta Morey, Mariana Vásquez Arimuya, Walter A. Boeger

Abstract: Biotodomella gen. nov. (Monogenoidea: Dactylogyridae) is proposed to accommodate Biotodomella mirospinata sp. nov., found on the gills of Biotodoma cupido (Heckel, 1840) (“cara bonita” or “green-streaked eartheater”), a freshwater cichlid from the Peruvian Amazon. The new genus and species differ from other Neotropical dactylogyrids in having the hooks of each hook pair well-differentiated from the remaining pairs, shafts varying in robustness, weakly sclerotized expansions at the proximal end of shaft, and a dorsal anchor with grooved shaft, bifid point. This study represents the first record of a monogenoid from a species of Biotodoma Eigenmann & Kennedy, 1903.

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DOI: 10.3897/zoologia.36.e25083

Authors: Flavia D.F. Sampaio, Helena C. Silva-de-Assis, Franciele L. Bettim, Luís F. Fávaro, Carolina A. Freire

Abstract: Pomacentridae is a common family in the aquarium fish trade. Most species are harvested from nature. Here we evaluate the following water parameters in the pomacentrid sergeant major, Abudefduf saxatilis (Linnaeus, 1758), to assess their stress level during a 24, 48, and 72 hours transport: dissolved oxygen (DO), total ammonia, and pH. In addition, we evaluated the following physiological parameters: plasma osmolality, muscle water content, blood glucose, and the enzyme activities of the branchial carbonic anhydrase (CA), the hepatic glutathione S-transferase (GST), catalase (CAT), and superoxide dismutase (SOD). The mortality of fish measuring >6 cm total length was 22%, while no mortality was observed for fish measuring <6 cm. The pH of the water was significantly correlated with fish mortality, especially for the initial 24 hours of transport. Hypoxia after 24–48 hours also led to fish mortality, but build up ammonia was not a problem even after 72 hours. We suggest that a minimum water volume of 125 ml/g fish is necessary for safe and cost-effective transport of the sergeant major, preferably with <6 cm in total length.

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DOI: 10.3897/zoologia.34.e20475

Authors: Lygia C. Ruas, André M. Vaz-dos-Santos

Abstract: The rough scad, Trachurus lathami Nichols, 1920, is a small pelagic species distributed along the West Atlantic coast. It is most abundant in the Southern Brazil (28°30’–34°S) and in the Southeastern Brazilian Bight (SEBB, 22°–28°30’S). The rough scad is fished by purse seines, which main target is the Brazilian sardine, Sardinella brasiliensis (Steindachner, 1879). Age and growth are vital to understand the life cycle of a species, to fishery management and ecosystem modeling. This study aimed to assess the age and growth of T. lathami, to identify its age structure in the SEBB, and to evaluate what causes the wide differences among Trachurus species in terms of body size and growth parameters. Data available on T. lathami was attained between 2008 and 2010 from surveys at SEBB. A total of 278 whole otoliths of T. lathami, total length between 27 mm and 208 mm, were analyzed and compared with the only other source of otolith data, from 1975. Three blind readings were performed and assessed using traditional methods to study fish age and growth. Zero up to eight rings were found, each ring corresponding to one year in the life of an individual of this species. The von Bertalanffy growth model parameters were L∞ = 211.90 mm and K = 0.319 year-1. The results of the analyses have shown similarities between 1975 and 2008-2010, indicating that the otolith development, the growth pattern and the age structure remained stable. T. lathami is the smallest species of Trachurus and it has the highest growth rates among them. This is probably related to the different temperatures where larvae/juvenile and adult grow, to the absence of a strong fishing pressure and to decadal population variability.

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