Quantitative risk-benefit assessment of Portuguese fish and other seafood species consumption scenarios

Portugal has high fish/seafood consumption, which may have both risks and benefits. This study aims to quantify the net health impact of hypothetical scenarios of fish/seafood consumption in the Portuguese population using a risk-benefit assessment methodology. Consumption data from the National Food, Nutrition and Physical Activity Survey 2015-2016 (n=5811) was used to estimate the mean exposure to methylmercury and EPA+DHA in the current and the alternative scenarios considered. Alternative scenarios (alt) were modelled using probabilistic approaches to reflect substitutions from the current consumption in the type of fish/seafood (alt1: excluding predatory fishes; alt2: including only methylmercury low-level fishes) or in the frequency of weekly fish/seafood consumption (alt3 to alt6: 1,3,5 or 7 times a week, replacing fish/seafood meals with meat or others). The overall health impact of these scenarios was quantified using Disability-Adjusted Life Years (DALYs). In the Portuguese population, about 11450 DALYs could be prevented each year if the fish/seafood consumption increased to a daily basis. However, such a scenario would result in 1398 extra DALYs considering the consumption by pregnant women and the respective risk on foetal neurodevelopment. Our findings support a recommendation to increase fish/seafood consumption up to 7 times/week. However, for pregnant women and children, special considerations must be proposed to avoid potential risks on foetal neurodevelopment due to methylmercury exposure.

Comparative cytogenetic patterns in Carangidae fishes in association with their distribution range

Carangidae are an important and widespreaded family of pelagic predatory fishes that inhabit reef regions or open ocean areas, some species occupying a vast circumglobal distribution. Cytogenetic comparisons among representatives of its different tribes help to understand the process of karyotype divergence in marine ecosystems due to the variable migratory ability of species. In this sense, conventional cytogenetic investigations (Giemsa staining, Ag-NORs, and C-banding), GC base-specific fluorochrome staining and FISH mapping of ribosomal DNAs were performed. Four species, Elagatis bipinnulata (Quoy et Gaimard, 1825) and Seriola rivoliana (Valenciennes, 1883) (Naucratini), with circumtropical distributions, Gnathanodon speciosus (Forsskål, 1775) (Carangini), widely distributed in the tropical and subtropical waters of the Indian and Pacific oceans, and Trachinotus carolinus (Linnaeus, 1766) (Trachinotini), distributed along the western Atlantic Ocean, were analyzed, thus encompassing representatives of three out its four tribes. All species have diploid chromosome number 2n = 48, with karyotypes composed mainly by acrocentric chromosomes (NF = 50–56). The 18S rDNA/Ag-NORs/GC+ and 5S rDNA loci were located on chromosomes likely homeologs. Karyotypes showed a pattern considered basal for the family or with small variations in their structures, apparently due to pericentric inversions. The migratory capacity of large pelagic swimmers, in large distribution areas, likely restricts the fixation of chromosome changes in Carangidae responsible for a low level of karyotype diversification.

How Raccoons Could Lead to the Disappearance of Native Crayfish in Central Italy

The white-clawed crayfish Austropotamobius pallipes complex populations are decreasing in the Foreste Casentinesi, Monte Falterona and Campigna National Park (Central Italy), due to several factors, including illegal poaching, predatory fishes, drought, and invasive alien species. Recently, the Northern raccoon Procyon lotor has been reported to be present in the area of the National Park and has started to predate on the white-clawed crayfish. The aim of the study was to update the distribution and population status of A. pallipes in the reserves, other sites of the National Park, and surrounding areas to assess the potential effects of the raccoon. Crayfish were sampled by hand or by traps in 14 sites; sampled individuals were sexed and measured. Signs of raccoon presence (e.g., footprints and predated crayfish) were also recorded. Our study confirms the impact of raccoon on native crayfish: indeed, where the invasive mammal is present (six sites), crayfish disappeared, or their populations have been dramatically reduced in number, with a size distribution skewed towards juveniles. In two sites, close to urban settlements, fresh footprints of P. lotor and predated specimens of A. pallipes were also observed. Populations of crayfish are still abundant or even increasing as compared with samplings conducted in the past where raccoon is absent (five sites). Urgent actions (e.g., control of raccoons, and monitoring and restocking of A. pallipes populations if feasible and where possible) should be taken into account to guarantee the survival of this protected species.

­­Effect of multimodal cues from a predatory fish on refuge use and foraging on an amphidromous shrimp

Background Prey can alter their behavior when detecting predator cues. Little is known about which sensory channel, number of channels, or the interaction among channels that shrimp species use to evaluate the threat from predators. The amphidromous shrimp Xiphocaris elongata has an induced defense, an elongated rostrum, where predatory fishes are present. We sought to test if kairomones or visual cues when presented singly from fish either eating flakes or shrimp, had more effect on altering the temporal feeding and refuge use patterns of long-rostrum (LR) X. elongata. We were also interested in elucidating potential interactions among cues when presented simultaneously in different combinations (kairomones + visual + mechanosensory, kairomones + alarm + visual, kairomones + alarm, kairomones + visual) on the same response variables. We expected that when presented alone kairomones will significantly increase refuge use and decrease foraging, particularly late at night, in comparison to visual cues alone, and that multiple cues when presented simultaneously will further increase refuge use and decrease foraging at night. Methods We exposed shrimp to individual or multiple cues from the predatory fish mountain mullet, Augonostomus monticola. We examined shrimp behavior with respect to refuge use and foraging activity during four time periods (after sunset, nighttime, sunrise, and sunset) in a 24-hour period. Results Shrimp presented fish visual and chemical cues singly did not differ from one another but differed from control shrimp (no cues) with respect to refuge use or foraging. The number of shrimp using refuge in the treatment with most cues (KVM: kairomones+ visual + mechanosensory) was higher than in all the treatments with less cues. A significant decline in foraging was observed when multiple cues were presented simultaneously. The highest number of shrimp foraged one hour after sunset and at nighttime. A significant interaction was observed between cue treatments and time periods, with shrimp in the KVM treatment foraging less and using more refuge late at night and at sunrise than shrimp in other treatments or time periods. Conclusions The observation that fish chemical and visual cues when presented singly produced similar refuge use and foraging patterns was contrary to expectation and suggests that visual and chemical cues, when presented alone, provide redundant information to X. elongata with regards to predation threat. The significant increase in refuge use and reduction in foraging observed in the KVM treatment suggest multimodal signal enhancement in the perception of threat. This makes evolutionary sense in “noisy” environments, such as streams, where detection, localization, and intention of predators is much improved when cues are received through multiple sensory channels.

Socio-economic portrait of Polish anglers: implications for recreational fisheries management in freshwater bodies

Recreational fisheries are an important element of contemporary fisheries. Detailed information about the motivation and opinions of anglers regarding catch-and-release fishing in post-communist countries, such as Poland, has not been widely available to date. The aim of this study was to fill this gap. We obtained 936 survey questionnaires completed by anglers from throughout Poland. The mean annual catch of a Polish angler is 126 fish weighing 46.1 kg. Anglers catch mainly cyprinids, but they would prefer to catch large predatory fishes, and they spend an average of 416.50 EUR on this activity annually. These results confirm the hypothesis that angling catches in Poland are decidedly of a recreational character and that catches targeted at fish consumption are of lesser importance. Simultaneously, we determined that younger anglers are more willing to release caught fish than older anglers.

Effects of marine reserves on predator-prey interactions in central California kelp forests

Marine reserves are often designed to increase density, biomass, size structure, and biodiversity by prohibiting extractive activities. However, the recovery of predators following the establishment of marine reserves and the consequent cessation of fishing may have indirect negative effects on prey populations by increasing prey mortality. We coupled field surveys with empirical predation assays (i.e. tethering experiments) inside and outside of 3 no-take marine reserves in kelp forests along the central California coast to quantify the strength of interactions between predatory fishes and their crustacean prey. Results indicated elevated densities and biomass of invertebrate predators inside marine reserves compared to nearby fished sites, but no significant differences in prey densities. The increased abundance of predators inside marine reserves translated to a significant increase in mortality of 2 species of decapod crustaceans, the dock shrimp Pandalus danae and the cryptic kelp crab Pugettia richii, in tethering experiments. Shrimp mortality rates were 4.6 times greater, while crab mortality rates were 7 times greater inside reserves. For both prey species, the time to 50% mortality was negatively associated with the density and biomass of invertebrate predators (i.e. higher mortality rates where predators were more abundant). Video analyses indicated that macro-invertivore fishes arrived 2 times faster to tethering arrays at sites inside marine reserves and began attacking tethered prey more rapidly. The results indicate that marine reserves can have direct and indirect effects on predators and their prey, respectively, and highlight the importance of considering species interactions in making management decisions.