Length-weight relationships of 28 fish species caught from demersal trawl survey in the Middle Black Sea, Turkey

This study provides updated the length-weight relationships and Fulton's condition factor of 28 fish species belonging to 23 families from the Black Sea. Samples were collected along the depths between 0-100 meters by demersal trawl surveys conducted seasonally from May 2017 to September 2019. A total of 83,885 specimens were collected. The length-weight relationships and Fulton's condition factor, minimum, maximum and mean lengths, total weights, descriptive statistics, and growth type were provided for all the species. The results indicate that LWR parameters of b varied from 2.2039 to 3.737 and Fulton's condition factor varied between 0.004 and 1.18. These findings could be useful for monitoring and management of sustainable fisheries and habitat health

Monthly variation in the morphological characteristics of Trichodina sp. (Ciliophora: Peritrichida) found on whiting Merlangius merlangus euxinus

To determine the existence and extent of seasonal variation in morphological characteristics of Trichodina sp., sixty whiting Merlangius merlangus euxinus were sampled monthly for one year, from the Eastern Black Sea coast of Turkey, using a line and hook. Strong seasonal morphological variations were detected; the denticle span, blade length and ray length showed significant seasonal variation, especially in June. The timing of primary production in the Black Sea and the changes in cellular organelles suggested a negative relationship between the body diameter of trichodinids and food availability in the surrounding environment

A survey of viral haemorrhagic septicaemia virus in cultured sea bass and its virulence on juveniles of sea bass, Dicentrarchus labrax (Actinopterygii: Perciformes: Moronidae) and gilthead sea bream, Sparus aurata (Sparidae)

Background. Turkey is one of the major European seed producers of European sea bass, Dicentrarchus labrax (Linnaeus, 1758), and gilthead sea bream Sparus aurata Linnaeus, 1758.  Determination of susceptibility to viral haemorrhagic septicaemia (VHS), a notifiable disease in Europe, is crucial particularly for sea bass and sea bream seed production to develop control measures and to take necessary actions in case of a VHS outbreak.  We hypothesized that VHS virus does not replicate at 16°C and above—the temperature range typical for hatcheries in the Aegean region. Materials and methods. To assess the seasonal occurrence and virulence of viral haemorrhagic septicaemia virus genogroup Ie (VHSV-Ie), a virological survey was conducted in cultured sea bass in the Black Sea. Thirty-five sea bass were sampled monthly from a local marine farm, and examined virologically.  Triplicate groups of juvenile of sea bass (n = 30 per replicate or n = 40 per replicate) and gilthead sea bream (n = 20 per replicate) were challenged by immersion with VHSV-Ie at 12°C and 16°C to determine the occurrence of pathogen transfer and viral replication.  Results. VHSV-Ie, or any other viral pathogen able to infect BF-2 and CHSE-214 cells, did not occur in cultured sea bass of the Turkish Black Sea region. It was impossible to infect sea bass at 16°C but moderate levels of mortality occurred at 12°C. Sea bream, however, were susceptible to VHSV-Ie, presenting low levels of mortality (15%). Conclusion. VHSV-Ie poses no risk to the production of sea bass seed carried out at 16°C and above, but sea bass and sea bream should be monitored for VHSV-Ie where ambient water temperature is below 16°C since the risk of introduction is present.