Pleistophora hippoglossoideos. [Descriptions of Fungi and Bacteria].

A description is provided for Pleistophora hippoglossoideos, which infects Hippoglossoides platessoides, American plaice (family Pleuronectidae) and Solea solea, the Dover sole (family Soleidae), in the North Atlantic, Baltic Sea and Arctic Ocean. Some information on its morphology, dispersal and transmission and conservation status is given, along with details of its geographical distribution (Europe (Baltic Sea, Norway, UK) and North America (Canada, Nova Scotia)) and hosts (Hippoglossoides platessoides, H. limandoides and Solea solea).

Growth pattern, mortality and reproductive biology of common sole, Solea solea (Linneaus, 1758), in the Sea of Marmara, Turkey

The study deals with the growth pattern, mortality, and reproduction of common sole, Solea solea (Linneaus, 1758), from the Sea of Marmara (Turkey). A total of 580 fish specimens were sampled monthly from October 2017 to September 2018. The total length of all sampled individuals ranged from 11.1 to 29.5 cm, corresponding to ages from 1 to 3 years. The length–weight relationship was expressed as W = 0.022 TL2.6838, where the slope indicated negative allometric growth. Growth parameters were L ∞ = 33.7 cm, k = 0.48, and t 0 = −0.18 for all samples. A seasonally oscillating growth model, indicating the amplitude of oscillations, revealed an important seasonal growth pattern. Total, natural, and fishing mortality rates were calculated as 1.42, 0.47, and 1.01, respectively. The exploitation ratio (E = 0.68) indicates that the fishing pressure on the common sole in the Sea of Marmara was high. The sex ratio (♀/♂) was 1.18. The gonadosomatic index (GSI) for females showed that two main spawning seasons were observed: one in spring (May) and one in autumn (September–October). Sizes at the onset of sexual maturity were estimated for both females and males at 21.6 and 18.6 cm, respectively.

Validating a biophysical dispersal model with the early life-history traits of common sole (Solea solea L.)

Larval dispersal and juvenile survival are crucial in determining variation in recruitment, stock size and adult distribution of commercially important fish. This study investigates the dispersal of early-life stages of common sole (Solea solea L.) in the southern North Sea, both empirically and through modeling. Age at different life-history events of juvenile flatfish sampled along the coasts of Belgium, the Netherlands and the United Kingdom in 2013, 2014 and 2016, was determined through the counting of daily growth rings in the otoliths. Juveniles captured between August and October were estimated to be on average 140 days old with an average pelagic larval duration of 34 days. The hatching period was estimated between early April and mid-May followed by arrival and settlement in the nurseries between May and mid-June. Growth rates were higher off the Belgian coast than in the other nursery areas, especially in 2013, possibly due to a post-settlement differentiation. Empirical pelagic larval duration and settlement distributions were compared with the Larvae&Co larval dispersal model, which combines local hydrodynamics in the North Sea with sole larval behavior. Yearly predicted and observed settlement matched partially, but the model estimated a longer pelagic phase. The observations fitted even better with the modelled average (1995–2015) distribution curves. Aberrant results for the small juvenile sole sampled along the UK coast in March 2016, led to the hypothesis of a winter disruption in the deposition of daily growth rings, potentially related to starvation and lower food availability. The similarities between measured and modelled distribution curves cross-validated both types of estimations and accredited daily ageing of juveniles as a useful method to calibrate biophysical models and to understand early-life history of fish, both important tools in support of efficient fisheries management strategies.

Radiological risks assessment due to natural radioactivity in Mediterranean sea fishes

Background and Objectives: In this article a comprehensive study was carried out for the determination of natural radioactivity in Mediterranean sea fishes and the evaluation of radiological health risks due to their ingestion. All analyzed samples came from the Calabria region, southern Italy, and, in particular, from the district of Reggio Calabria. Method: A total of seventy representative samples, five for each investigated species (Sardina Pilchardus, Mugil Cephalus, Scomber Scombrus, Sparus Aurata, Dicentrarchus Labrax, Tonnus Thynnus, Thunnus Alalunga, Xiphaias Gladius, Pagellus Erythrinnus, Engraulis Encrasicholus, Belone Belone, Solea Solea, Merluccius Merluccius, Mullus Surmuletus) were analyzed through HPGe gamma spectrometry. The evaluation of dose levels and lifetime cancer risks for adult members of the population due to the fishes ingestion was also performed. Results: The specific activity of 40K was investigated and its mean value was found to be: (157 ± 17) for Sardina Pilchardus, (138 ± 14) for Mugil Cephalus, (118 ± 13) for Scomber Scombrus, (128 ± 14) for Sparus Aurata, (146 ± 17) for Dicentrarchus Labrax, (93 ± 11) for Tonnus Thynnus, (137 ± 15) for Thunnus Alalunga, (98 ± 10) for Xiphaias Gladius, (105 ± 12) for Pagellus Erythrinnus, (132 ± 14) for Engraulis Encrasicholus, (113 ± 12) for Belone Belone, (34 ± 5) for Solea Solea, (76 ± 9) for Merluccius Merluccius and (96 ± 11) for Mullus Surmuletus, respectively. Conclusions: The committed effective dose and the lifetime cancer risks for adult members of the population due to the consumption of the investigated samples are lower than the average world value, the maximum acceptable level and the allowed range, respectively. It can then be concluded that the Mediterranean sea fishes consumed in the study area pose no significant health risks to the population from a radiological point of view.

Parasitic isopods on some marine fishes caught from the coasts of Sinop in the Black Sea, Turkey

Marine fish species such as grey wrasse Symphodus cinereus, common sole Solea solea, knout goby Mesogobius batrachocephalus and rusty blenny Parablennius sanguinolentus were studied for their parasitic isopods on the Sinop coast of the Black Sea. Two cymothoid species (Nerocila bivittata and Nerocila orbignyi) were identified. Nerocila bivittata was found on the body surface and fins of grey wrasse, common sole, knout goby, and N. orbignyi on the dorsal fin of rusty blenny. The prevalence and mean intensity values of each parasite species on fishes were calculated. Fish species mentioned above were all new hosts for N. bivittata and N. orbignyi in the Turkish coast of the Black sea.