Reproductive Cycle and Size at First Maturity in Females of Brown Crab Callinectes Bellicosus (Stimpson 1859) in the Southwestern Gulf of California, Mexico

The reproductive cycle of the crustacean family Portunidae on the coast of the Pacific is not well known. Therefore, the reproductive cycle and the size at first maturity of brown crab Callinectes bellicosus and its relationship with environmental factors in the El Colorado Lagoon, Ahome, Sinaloa has been determined. A total of 360 females were collected from March 2012 to March 2013. The gonads were fixed in 10% formalin, histological cuts were made by the paraffin inclusion method and the hematoxylin and eosin staining technique. The diameter of oocytes was determined by stage. The size at first maturity was estimated by a logistic model. Females showed gametogenic activity during the entire study period. The maturity period was from March to November 2012, with two spawning peaks, in September 2012 and March 2013. Maturity was inversely influenced by temperature (r = -0.4454, P < 0.05) and no influence by salinity was observed (P > 0.05). The diameter of the oocytes showed significant differences between the development stages of the gonad (P = 0.001). The size at first maturity was 11.57 cm of carapace width for females of C. bellicosus.

Reproductive variables of Hypleurochilus fissicornis (Quoy & Gaimard, 1824) (Pisces: Blenniidae) on rocky intertidal zones in the South-western Atlantic

Hypleurochilus fissicornis is a resident species of the intertidal and subtidal zones of Mar del Plata, Argentina. The specific reproductive biology was studied by means of both microscopic and macroscopic analyses. A total of 212 males and 223 females were analysed. Specimens were dissected and their gonads and livers were removed. The gonadosomatic and hepatosomatic indexes and the condition factor were calculated on a monthly basis. Hypleurochilus fissicornis breeds in rocky intertidal areas, and exhibits low fecundity with benthic eggs and parental care. Size at first maturity (L50) was estimated at 53.66 and 55.83 mm total length for females and males, respectively. The spawning season takes place between December and April.

REPRODUCTION ASPECTS OF COBIA CAUGHT IN PERNAMBUCO COAST, NORTHEASTERN BRAZIL

Aspects of the reproduction of cobia (Rachycentron canadum) population from the coast of Pernambuco State, Northeastern Brazil, were studied from February 2004 to August 2006. One hundred eleven individuals were analyzed: 54 females with fork length (FL) ranging from 40 to 137 cm (mean ± standard deviation: 90.7 ± 18.1 cm) and 57 males with FL from 43 to 114.5 cm (82.4 ± 17.0 cm). Histological analysis was used to identify maturational phases. Spawning capable females were found from August to May, except in December, while mature males were present throughout the year, except in July. Size at first maturity (L50) obtained by Bayesian analysis was 72.51 cm FL for females and 60.69 cm FL for males. Overall batch fecundity ranged from 192,063 to 1,600,513 oocytes (722,398 ± 430,911) and mean relative batch fecundity ranged from 32.9 to 104.8 (71.1 ± 29.8) oocytes per gram of female body weight. The data indicate that the reproduction of cobia off the coast of Pernambuco occurs throughout the year, but with peaks between February and April, period in which gonadosomatic indices reach the maximum values and then decrease until May for females and males.

Maturation Biology and Spawning Ethos of A Hillstream Loach Lepidocephalus Guntea (Ham-Buch) From River Mandal, Pauri Garhwal, Uttarakhand

The paper deals with studies on maturation biology and spawning behaviour of an important hill stream loach Lepidocephalus guntea (Ham-Buch) from river Mandal in District Pauri Garhwal Uttarakhand. It was observed that there was a continuous growth of ova throughout the year. Seven maturity stages in the fish were observed with single mode each month. Gonado-somatic index (GSI) and Dobriyal Index (DI) were calculated to find out the month of peak maturity, spawning frequency and spawning season. It was confirmed by tabulation of fishes in different maturity stages each month and also by physical observations in the field. It was concluded that June was the month of peak maturity and spawning takes place during July- August. Rare spawning was seen even in First week of September. Size at first maturity was 60-61 mm.

Contribution to the reproductive ecology of Notoscopelus resplendens (Richardson, 1845) (Myctophidae) in the Central-Eastern Atlantic

Notoscopelus resplendens is an abundant myctophid in the region of the Central-Eastern Atlantic. As with a majority of other myctophid species, this species performs vertical migration, playing a key role in the oceanic food web and in carbon sequestration. We examined the reproductive biology of N. resplendens based on 579 specimens caught between 1997 and 2002 off the Canary Islands. We found that the maximum standard length (SL) was lower than the size reported by other authors. The sex ratio was not different from 1:1. The average size at first maturity (L50) was higher in females (60.34 mm SL) than in males (56.61 mm SL). The gonadosomatic index (GSI) at 50% sexual maturity in females was higher than that in males. The reproductive activity was observed from January to April, while from May onwards, the majority of fish caught were in the process of maturation. The macroscopic scale of maturation was validated through the histological analysis of the ovarian development. The batch fecundity was related to the standard length, with an average of 1068.69 ± 369.84 eggs/spawn. These first data obtained for N. resplendens indicated that it is a batch spawner with asynchronous ovarian development.

Fecundity, histomorphology of the ovary and size at first maturity of Neolissochilus hexagonolepis (McClelland) in Tamor River, Nepal

Neolissochilus hexagonolepis (McClelland, 1839) is one among the notable species in snow-fed torrential rivers of Nepal. The present study attempts to investigate some reproductive traits of N. hexagonolepis, including the length at first maturity, fecundity and its relationships with biometric variables like lengths (TL, SL, and FL) and weights (TW and OW) of the fish in the mid-reaches of Tamor River, Nepal. A total of 109 fish samples were collected from the river. For each individual, total length (TL), standard length (SL) and fork length (FL) were measured in a fully stretched condition to the nearest 1mm using a measuring tape and graduated ruler, while total weight (TW) and ovary weight (OW) was measured using a digital balance with the precision of 0.01 g. The mean absolute fecundity (F) was 8356.44 ± 4612.59 and ranged from 2398.6 to 20160. SL was more significantly correlated with absolute fecundity (R2=0.59; p<0.001) than other body metrics. The results showed that female individuals of N. hexagonolepis attained the first sexual maturity at TL 32.9 cm. N. hexagonolepis exhibited a protracted breeding period with its ovaries passing through six different stages of maturation. The finding of the present study may serve as a protocol for fishery biologists and managers to promulgate adequate regulations for continual fishery management in the River Tamor, Nepal.

Trophic ecology of the fish Leporinus piau (Characiformes: Anostomidae) in an area influenced by a dam in the Parnaíba River

Introduction: Hydroelectric dams have several impacts on migratory fish, such as decreasing their abundance, local extinctions, and changes in the assemblage structure. Objective: To investigate the trophic and reproductive strategies of Leporinus piau upstream and downstream from a hydroelectric dam in the Parnaíba River. Methods: We identified food items and calculated trophic niche breadth in both sites to characterize the feeding strategy. We conducted permutational multivariate analysis of variance (PERMANOVA) to determine differences in diet between sites, followed by a SIMPER analysis in order to show which items were the most dissimilar. To characterize the reproductive strategy, we analyzed weight/length relationship, body condition factor, gonadosomatic index, and size at first maturity. Results: Leporinus piau was classified as an omnivore with a predominantly plant-based diet at both sites. The diet and niche breadth varied between sites. The condition factor differed between sites while size at first maturity differed between sites and sexes. Conclusions: Leporinus piau variations upstream and downstream from a hydroelectric dam in the Parnaíba River are results of differences in life histories traits, as identified in the life history theory, which clarifies the differences on trophic and reproductive strategies.