Efficacy of fresh crushed leaves and essential oil of Eucalyptus camaldulensis Dehnh on larvae of Dermestes maculatus De Geer insect damage to smoked dried Sardinella aurita "Kétiakh" stored in Senegal

Synthetic pesticides used to protect stored smoked and dried fish often cause enormous damageto human health and the environment. To limit the harms due to the use of these chemicals, it is necessary to find alternative methods. For this purpose, natural substances may constitute a beneficial way. The objective of this work is to study the effect of crushed fresh leaves and essential oil of Eucalyptus camaldulensis on the mortality of the larvae of an insect pest of smoked and dried fish, Sardinella aurita "Kétiakh", Dermestes maculatus (De Geer, 1774). Essential Oil was obtained by steam distillation from Eucalyptus leaves (0.8% w/w) and analyses carried out by GC/FID and GC/MS. For the biological test, fresh crushed leaves and essential oil were tested at different doses at varying treatment times again larvae Dermestes maculates. The results showed that D. maculatus was sensitive for both fresh crushed leaves and the essential oil, the efficacy of which depended on the dose and duration of treatment. The doses of 2 g and 2.5 g of freshly ground leaves showed a high efficiency of 27 to 40%, of mortality respectively. However, for the essential oil, with the increase in the duration of exposure, the highest mortality (33.3%) was recorded after 72 hours of treatment with the 40µl dose and at 120 hours with the 60µl dose. This study showed that fresh crushed leaves and essential oil of Eucalyptus camaldulensis can be considered as an alternative to the use of chemical insecticides in the conservation of smoked and dried Sardinella aurita "Kétiakh" stored in Senegal.

On the maximum length for Sardinella aurita (Osteichthyes: Clupeidae) from the Mediterranean Sea

Two specimens of round sardinella, Sardinella aurita Valenciennes, 1847, with a total length of 39.1 and 36.6 cm and a weight of 359.01 and 293.48 g, respectively, were caught by a purse seine net in Bouzedjar Bay, Algeria, on 8 August, 2019. These sizes of both specimens are the maximum recorded for this species in the Mediterranean Sea.

Dinámica poblacional de sardina (Sardinella aurita) del estado Nueva Esparta, Venezuela

La pesca de sardina (Sardinella aurita) es muy abundante en las costas de los estados Sucre y Nueva Esparta de Venezuela, y está asociada con la intensidad de vientos y con la temperatura superficial del mar. Por tal razón, el objetivo del presente trabajo fue determinar la dinámica poblacional estimando los parámetros reproductivos, crecimiento y mortalidad para contribuir a la evaluación y manejo de la pesquería. Se realizaron muestreos mensuales en el estado Nueva Esparta durante la temporada de pesca (marzo-diciembre) de 2019, y se analizaron 3,679 ejemplares a los cuales se les registró longitud total (cm), peso total (g), sexo y madurez sexual. La proporción sexual obtenida fue de 1.4:1 hembras a machos, la cual difirió significativamente de una proporción 1:1 a un nivel de confianza de 95% (χ2 = 86.58; p < 0.05). Se observaron tres pulsos de desove (mayo, julio y noviembre). La talla media de madurez sexual fue de 19.53 cm. Los resultados demostraron que no existe diferencia entre sexos con respecto a la longitud (ts = 0.80; p > 0.05), por lo que se estimó la relación longitud-peso para ambos sexos: P = 5.4 x 10-3 * L3.13, mostrando un crecimiento isométrico. En la estimación del crecimiento se utilizaron las rutinas del paquete FiSAT para estimar los parámetros del modelo de crecimiento individual de von Bertalanffy: L∞ = 23.30 cm, k = 0.71 año-1, P∞ = 103.18 g, t0 = - 0.12 años, en tanto que el índice de desempeño del crecimiento (Ø') fue de 2.59. Se determinó una edad máxima de 4 años. La tasa de explotación actual (E = 0.59 año-1) se calculó a través de la mortalidad total Z = 2.66 año-1 (r = 0.99) obtenido de la curva de captura linearizada, la mortalidad por pesca F = 1.57 año-1 y mortalidad natural M = 1.09 año-1, indicando que la sardina se encuentra en plena explotación; por consiguiente se sugiere evitar el aumento del esfuerzo de pesca.

Retention probability of purse seine grating sieve based on fish morphology

The retention-releasing patterns of the double-grid grating sieve placed on the deck of the purse seiners were revealed for four case species (Sardina pilchardus, Sardinella aurita, Engraulis encrasicolus and Boops boops) using a simulated data predicted from total length (TL) – maximum height (Hmax) and TL – maximum width (Wmax) regressions. To calculate these relationships, samples were collected during commercial purse seine operations between 3 April 2017 and 21 March 2018 in Izmir Bay, Aegean Sea (Turkey). Optimal Bar Spacing (OBS) values corresponding to minimum landing sizes or the length at first maturity were calculated separately for each species. OBS values were found 10.97 mm for sardine (Sardina pilchardus), 11.29 mm for round sardine (Sardinella aurita), 7.78 mm for anchovy (Engraulis encrasicolus) and 17.89 mm for bogue (Boops boops). The bar spacing regulations may constitute a promising management measure to release undersized fish for the purse seine fishery in the Aegean Sea.

Age, Growth and Ovarian Histology of Sardinella aurita (Valenciennes, 1847) in the South of Atlantic Moroccan Coast

Otoliths reading and length frequency distribution were used for age determination and growth estimation of Sardinella aurita (round sardinella) stock of Southern Atlantic coast of Morocco. Both otoliths' method for age determination and Bhattacharya’s method for length frequency analysis showed five age groups. The growth performance index revealed that there is significant accordance among method of length frequency distribution and otoliths reading for stock assessment studies of Sardinella aurita stock in the south of Morocco. The microscopic observation of female gonads using histology method was investigated for the first time in our study area and confirms the presence of five principal stages of ovary of sardinella aurita: immature, maturing virgin and recovering spent, mature (or pre-spawning phase), spawning, post-spawning or spent. In addition, our results of the fecundity showed that the mean relative fecundity obtained is estimated at 193 ± 98 oocytes/g which is lower compared to those obtained in other areas in the Atlantic coast.

Parasitic fauna of Sardinella aurita Valenciennes, 1847 from Algerian coast

The parasitic fauna of Sardinella aurita Valenciennes, 1847 from the Gulf of Bejaia (eastern coast of Algeria) was studied. The parasites collected from 400 host fish specimens, comprised 10 taxa including 6 species of Digenea, 1 species of Copepoda, 1 species of Nematoda, 1 larva of Cestoda and an unidentified Microsporidian species. The Nematoda Hysterothylacium sp. and the Copepoda Clavellisa emarginata (Krøyer, 1873) are newly reported for S. aurita. The Digenean parasites were numerous, diverse and constituted the most dominant group (P = 33.63%). The checklist of all known parasite species collected from S. aurita in the Mediterranean Sea includes 13 species, among which eight are Digeneans.

Species diversity and dominancy indexes in Izmir Bay (Aegean Sea) purse seine fishery

To determine the diversity index values of species caught by purse seine, all samplings were carried out between September 2, 2017, and April 6, 2018 in Izmir Bay. As a result, a total of 17 fish species (Osteichthyes) belonging to 11 families and also 2 species from invertebrates (Cephalopoda and Arthropoda) were determined. Bony fishes and invertebrates consist of 99.9% and 0.1% of the total biomass, respectively. Sardina pilchardus was the most dominated species that occupied as 80.2% of the overall bony fishes followed by Engraulis encrasicolus (14.6%) and Sardinella aurita (1.5%). Diversity index values of species were found-1.026 by Shannon-Weaver and 0.63 by Simpsons, respectively. The highest dominancy was found for S. pilchardus with 71.1%. Overall final results indicate that the diversity of species in Izmir Bay purse seine fishery is very low and also S. pilchardus is the most over-dominant species.