Analysis of sizes and state of ovarian maturity in yellowfin tuna (Thunnus albacares) captured in the Gulf of Mexico

The yellowfin tuna Thunnus albacares is the second most important fishery in Mexico, due to its production costs and commercial value” The species is fished on both coast of the country, with the Pacific Ocean presenting productions lightly higher than that of the Gulf of Mexico where, in spite of the above statement, tuna catches have recently shown a downward trend. For this reason, analysis is required of the size and stage of ovarian maturity and it is necessary to determine whether capture size is the primary reason behind the decline in the yellowfin tuna fishery Three tuna fishing trips were conducted in the Gulf of Mexico in order to gather data pertaining to fork length (Lf) and gonads Histological sections were obtained from the latter for analysis and determination of maturity stage. The results showed that males were predominant (40%) among the individuals for which the sex could be differentiated in the catches of T. albacares. The Lf values in the catch, were between 75 and 162 cm. However, variations in this parameter were found between sexes. The relationship between length and weight showed that the males are larger than the females, however, the equationgiven by the parameters of a=0.9406 and b= 3.4504, demonstrated growth of positive allometric type in both sexes. There was progressive development in the state of ovarian maturity over the months of capture. Chromatin nuclear (CN) was the most frequent phase within primary ovarian development (November, February, March), stages were present, although these did not present a direct relationship to fork length.

Impact of sex ratio on the spawning success of zebrafish in the laboratory settings

Zebrafish, Danio rerio belonging to the family Cyprinidae is one of the most important native ornamental model species used in fisheries research globally. The present study was conducted to evaluate the effects of sex ratio on the spawning of zebrafish and to observe the ovarian maturity in the laboratory condition. This experiment was conducted for 12 weeks in the glass aquaria (25×16×26 cm3 in size) and the zebrafish were reared in five different sex ratio treatments like -T1 (1m:1f), T2 (1m:2f), T3 (1m:3f), T4 (2m:1f) and T5 (3m:1f) and the fertilized eggs were collected daily from the aquaria. The results showed that mean number of eggs was found to be highest at T3 (821±67.11) and the average egg lay day interval was 1.9 days which significantly (p<0.05) differ from other treatments. These research findings will provide a guideline to small scale fish farmers, entrepreneurs and hatchery owners to develop the spawning of zebrafish in the laboratory settings with a little investment. It will also provide opportunities to construct zebrafish hatchery and produce commercially zebrafish fry in a large extent. Progressive Agriculture 32 (1): 78-83, 2021

THE EFFECT OF KATUK (Sauropus androgynus L. Merr) ETHANOL EXTRACT ON OVARIAN MATURITY OF MUD CRAB (Scylla sp)

Katuk leaves are plants that contain sterols. Sterols are steroid precursors used for the development of mud crab ovaries. This study aims to determine the development of mangrove crab ovaries by giving katuk leaf extract. Stages of research include katuk leaf extraction, experiments by injecting the mother crab consisting of 3 treatments consisting of treatment A (control), treatment B (0.25 mg / g body weight), treatment C (0.5 mg / g body weight) ) maintained for 20 days by feeding trash fish and measuring parameters including morphological ovarian development, gonad somatic index, and hepatosomatic index. The results of the study on C treatment on the 20th day of observation by ovarian morphology have developed in the TKO IV phase, the final B TKO III treatment and the A-phase TKO III treatment. GSI on the 20th day in treatment C showed the highest GSI value of 16.1% and the lowest in treatment A was 12.2%. It can be concluded that the administration of katuk extract can accelerate the ovarian maturity of mud crabs.

Growth, mortality, ovarian maturity, and exploitation of the Guinea shrimp, Holthuispenaeopsis atlantica (Balss, 1914) (Decapoda: Dendrobranchiata: Penaeidae) in inshore waters of Ghana, West Africa

The Guinea shrimp, Holthuispenaeopsis (= Parapenaeopsis) atlantica (Balss, 1914) is exploited by traditional and commercial fisheries in the Gulf of Guinea, West Africa. We assessed growth, mortality, ovarian maturity, and exploitation of the population of the species in inshore waters of Ghana as a contribution of filling the knowledge gap on the species. Samples were obtained from fish landing sites from three different coastal towns in Ghana from October, 2017 to May, 2018. Length-frequency data were used to estimate growth, mortality and exploitation ratio. The modal class for males was 6.0–6.9 cm total length (TL) and 9.0–9.9 cm TL in females. The length and weight relationship established that growth in both sexes was negatively allometric. The estimated growth parameters from the length frequency data fitted with the von Bertalanffy growth function were asymptotic length (L∞) of 10.08 cm for males and 15.4 cm for females. The growth constant (K) was calculated as 0.99 yr–1 for males and 0.89 yr–1 for females. The mean length-at-first capture (Lc) was found to be lower than the mean length at sexual maturity (Lm). The sex ratio showed a preponderance of females over males throughout the period, with 76.21% females. The total mortality rate (Z) for males was more than for females. The estimated natural mortality was 2.32 yr−1 for males and 1.93 yr−1 for females (M) whiles fishing mortality (F) rate was 1.22 yr−1 for males and 1.46 yr−1 for females. The exploitation ratio showed the stocks were not over-exploited. The estimated population parameters of the species obtained should be significant for the sustainable management of this resource.