The general decline of seabird populations worldwide raises large concerns. Although multiple factors are interacting to cause the observed trends, increased mortality from incidental bycatch in fisheries has proven to be important for many species. However, the bulk of published knowledge is derived from longline fisheries, whereas bycatch in gillnet fisheries is less studied and even overlooked in some areas. We present seabird bycatch data from a 10-year time-series of fishery data from the large fleet of small-vessels fishing with gillnets along the Norwegian coast—a large area and fishery with no prior estimates of seabird bycatch. In general, we document high rates of incidental bycatch (averaging 0.0023 seabirds/net, or approximately 0.08 seabirds/fishing trip). This results in an estimated annual bycatch between 1580 and 11500 (95% CI) birds in this fishery. There was a surprisingly high percentage (43%) of surface-feeding seabirds in the bycatch, with northern fulmar being the most common species. Among the diving seabirds caught, common guillemot was most numerous. Our findings suggest that coastal gillnet fisheries represent a more general threat to a wider range of seabird populations, as opposed to longline fisheries where surface-feeding seabird species seem to dominate the bycatch. The bycatch estimates for the Norwegian gillnet-fishery varied in time, between areas, and with fishing depth and distance from the coast, but we found no clear trends in relation to the type of gillnets used. The results enabled us to identify important spatio-temporal trends in the seabird bycatch, which can allow for the development and implementation of more specific mitigation measures. While specific time closures might be an efficient option to reduce bycatch for diving seabirds, measures such as gear modification and reduction in release of wastewater during fishing operation are probably a more effective mitigation approach for reducing bycatch of surface-feeding seabirds.
This systematic review of peer reviewed articles on attitudes towards gray wolves (Canis lupus), shows that attitudes are mainly measured either by mean values of attitudes or by proportional differences in attitudes. This may impact on how attitudes are perceived and interpreted across studies and areas. However, independent of method used, we found that people living in areas where wolves always have existed, are more negative towards wolves compared to people living in areas where there are no wolves, or where wolves have recovered after years of absence. People who express fear, or being directly affected by having wolves, such as farmers and hunters, report more negative attitudes compared to other groups of respondents. For wolf conservation we recommend politicians and management authorities to prepare local societies of the different consequences of living in wolf areas. We recommend using dialogues and conflict management methods to minimize the level of conflicts.
Invasive alien species constitute a major threat to the world's freshwater ecosystems. Human translocations as well as rising temperatures have allowed freshwater fish species to expand their distribution into novel ecosystems, often with negative effects on native biodiversity. Early intervention is key to restricting damage and further spread of invasive aliens. This makes identification of areas with high risk for the establishment of invasive alien species necessary in order to target monitoring and mitigation measures. Here, we model lake‐specific likelihood of establishment of five freshwater fish species which are increasing their distribution in Norway. In order to establish the likelihood of establishment resulting from human translocation, environmental factors or natural dispersal from an established population, a suite of anthropogenic and environmental covariates were included as predictors. We used these models to create a future scenario which modelled establishment risk for these species over a 50‐year time period. Connectivity of lakes to other extant populations and anthropogenic covariates influenced likelihood of establishment—and subsequently future establishment risk—the most across all species. The effects of temperature were variable, and for the most part had little effect on likelihood of establishment. Our results indicate that human behaviour, infrastructure development and alternations of watershed connectivity are more important than climate induced range shifts on a short to medium time horizon. Synthesis and applications. Our study demonstrates how risk assessments of invasive establishment can be synthesised based on readily available open data sources. This allows for the construction of tools to forecast invasion hotspots as a basis for designing mitigation actions, including early monitoring programs, horizon scanning initiatives and eradication measures. It also allows managers to determine where species are spreading as a result of direct human translocation, and where they are expanding as a result of increased temperatures.
Fish swimming performance is strongly influenced by flow hydrodynamics, but little is known about the relation between fine-scale fish movements and hydrodynamics based on in-situ investigations. In the presented study, we validated the etho-hydraulic fish swimming direction model presented in the River Mandal from Southern Norway, using similar behavioral and hydraulic data on salmon smolts from the River Orkla in Central Norway. The re-parametrized model explained the variation of the swimming direction of fish in the Orkla system in same degree as the original model performed in the Mandal system (R2: 84% in both cases). The transferability of the model when using it from one river to predict swimming direction in the other river was lower (R2: 21% and 26%), but nevertheless relatively high given that the two localities differed in hydraulic conditions. The analyses thus provide support for the fact that the identified hydraulic parameters and their interaction affected smolt behavior in a similar way at the two sites, but that local parametrization of the base model is required. The developed etho-hydraulic models can provide important insights into fish behavior and fish migration trajectories and can be developed into prediction models important for the future development of behavioral downstream migration solutions.
The pathogenic fungus Batrachochytrium dendrobatidis (Bd) causes chytridiomycosis in amphibians across the world, often leading to population declines and species extinctions. Here, we present the first detection of Bd in Norway, diagnosed using environmental DNA (eDNA) in water samples. In a genetic screening of 31 ponds in southeastern Norway for Bd, great crested newt (Triturus cristatus) and smooth newt (Lissotriton vulgaris), we detected Bd in five different localities. Resampling in one location revealed that time of sampling seemingly had a strong effect on the concentration of Bd eDNA in the water, which increased from May till June. In contrast, eDNA concentration of great crested newt decreased during the same period. Following a traditional sampling approach with traps, newts in the investigated ponds have been sampled for population estimates since 2012. We imposed a model on the catch data and contrasted the Bd‐positive ponds to the Bd‐negative ponds, finding no signs of population declines in the Bd‐positive ponds. This could suggest either recent infection events, with animals still having low prevalence of Bd and with little time for Bd to affect the present breeding generations of newts, and/or that the two newt species are infection‐tolerant. This study further highlights eDNA as a tool for early detection of invasive species.