Distribution maps of cetacean and seabird populations in the North‐East Atlantic

1. Distribution maps of cetaceans and seabirds at basin and monthly scales are needed for conservation and marine management. These are usually created from standardized and systematic aerial and vessel surveys, with recorded animal den- sities interpolated across study areas. However, distribution maps at basin and monthly scales have previously not been possible because individual surveys have restricted spatial and temporal coverage. 2. This study develops an alternative approach consisting of: (a) collating diverse survey data to maximize spatial and temporal coverage, (b) using detection func- tions to estimate variation in the surface area covered (km2) among these surveys, standardizing measurements of effort and animal densities, and (c) developing species distribution models (SDM) that overcome issues with heterogeneous and uneven coverage. 3. 2.68 million km of survey data in the North-East Atlantic between 1980 and 2018 were collated and standardized. SDM using Generalized Linear Models and General Estimating Equations in a hurdle approach were developed. Distribution maps were then created for 12 cetacean and 12 seabird species at 10 km and monthly resolution. Qualitative and quantitative assessment indicated good model performance. 4. Synthesis and applications. This study provides the largest ever collation and standardization of diverse survey data for cetaceans and seabirds, and the most comprehensive distribution maps of these taxa in the North-East Atlantic. These distribution maps have numerous applications including the identification of im- portant areas needing protection, and the quantification of overlap between vul- nerable species and anthropogenic activities. This study demonstrates how the analysis of existing and diverse survey data can meet conservation and marine management needs.Versión del editor4,7

Distributional ecology of harbour porpoises in the Shetland Islands, North Scotland

No abstract available

Distributional ecology of harbour porpoises in the Shetland Islands, North Scotland

No abstract available

Harbour porpoise habitat preferences: robust spatio-temporal inferences from opportunistic data

Statistical habitat modelling is often flagged as a cost-effective decision tool for species management. However, data that can produce predictions with the desired precision are difficult to collect, especially for species with spatially extensive and dynamic distributions. Data from platforms of opportunity could be used to complement or help design dedicated surveys, but robust inference from such data is challenging. Furthermore, regression models using static covariates may not be sufficient for animals whose habitat preferences change dynamically with season, environmental conditions or foraging strategy. More flexible models introduce difficulties in selecting parsimonious models. We implemented a robust model-averaging framework to dynamically predict harbour porpoise Phocoena phocoena occurrence in a strongly tidal and topographically complex site in southwest Wales using data from a temporally intensive platform of opportunity. Spatial and temporal environmental variables were allowed to interact in a generalized additive model (GAM). We used information criteria to examine an extensive set of 3003 models and average predictions from the best 33. In the best model, 3 main effects and 2 tensor-product interactions explained 46% of the deviance. Model-averaged predictions indicated that harbour porpoises avoided or selected steeper slopes depending on the tidal flow conditions; when the tide started to ebb, occurrence was predicted to increase 3-fold at steeper slopes

From nought to 100 in no time: how humpback whales (Megaptera novaeangliae) came into the Southern North Sea

The humpback whale (Megaptera novaeangliae) has a cosmopolitan distribution: it occurs in all oceans and in many seas. Remarkably, the species was missing from the southern North Sea until recently. Even strandings of dead animals have always been very rare but from the 1990s onward this started to change. A trickle of dead humpback whales was the first sign that things were about to change, followed by sightings of live whales from 2001 on. Many of the first whales to arrive in the southern North Sea did not survive, and stranded, but this too has changed. Today, humpback whales visit the region every year in small numbers and both adults and juveniles are involved. The whales rarely fluke in the shallow coastal waters where they are mostly seen but a few wellmarked individuals have been seen in different years and some stayed up to several months in the area. It remains unclear what might have triggered this range extension. Numbers of humpback whales in the Atlantic are increasing after the cessation of whaling, but numbers are still short of the pre-whaling population size (when the species was absent from the southern North Sea). Some forage fish species, like herring (Clupea harengus) are also on the increase, but stocks are still depleted compared to the past. Most likely, therefore, something has changed in the whales themselves, causing them to be more inquisitive and to explore new waters. Once they have arrived in the southern North Sea, their behaviour shows that they can find sufficient food here