Behavioural heterogeneity across killer whale social units in their response to feeding opportunities from fisheries.

Intra-population heterogeneity in the behavioural response of predators to changes in prey availability caused by human activities can have major evolutionary implications. Among these activities, fisheries, while extracting resources, also provide new feeding opportunities for marine top predators. However, heterogeneity in the extent to which individuals have responded to these opportunities within populations is poorly understood.

Using ecotourism boats for estimating the abundance of a bottlenose dolphin population in south-eastern Australia.

It is challenging to collect robust, long-term datasets to properly monitor the viability and social structure of large, long-lived animals, especially marine mammals. The present study used a unique long-term dataset to investigate the population parameters and social structure of a poorly studied population of bottlenose dolphins (Tursiops sp.) in southern Port Phillip Bay, south-eastern Australia.

"Type D" killer whale genomes reveal long-term small population size and low genetic diversity.

Genome sequences can reveal the extent of inbreeding in small populations. Here, we present the first genomic characterization of type D killer whales, a distinctive eco/morphotype with a circumpolar, subantarctic distribution. Effective population size is the lowest estimated from any killer whale genome and indicates a severe population bottleneck.

Increasing numbers of killer whale individuals use fisheries as feeding opportunities within subantarctic populations.

Fisheries can generate feeding opportunities for large marine predators in the form of discards or accessible catch. How the use of this anthropogenic food may spread as a new behaviour, across individuals within populations over time, is poorly understood. This study used a 16-year (2003-2018) monitoring of two killer whale subantarctic populations ( and at Crozet), and Bayesian multistate capture-mark-recapture models, to assess temporal changes in the number of individuals feeding on fish caught on hooks ('depredation' behaviour) of a fishery started in 1996.

Runs of homozygosity in killer whale genomes provide a global record of demographic histories.

Runs of homozygosity (ROH) occur when offspring inherit haplotypes that are identical by descent from each parent. Length distributions of ROH are informative about population history; specifically, the probability of inbreeding mediated by mating system and/or population demography. Here, we investigated whether variation in killer whale (Orcinus orca) demographic history is reflected in genome-wide heterozygosity and ROH length distributions, using a global data set of 26 genomes representative of geographic and ecotypic variation in this species, and two F1 admixed individuals with Pacific-Atlantic parentage.

Killer whale genomes reveal a complex history of recurrent admixture and vicariance.

Reconstruction of the demographic and evolutionary history of populations assuming a consensus tree-like relationship can mask more complex scenarios, which are prevalent in nature. An emerging genomic toolset, which has been most comprehensively harnessed in the reconstruction of human evolutionary history, enables molecular ecologists to elucidate complex population histories. Killer whales have limited extrinsic barriers to dispersal and have radiated globally, and are therefore a good candidate model for the application of such tools.

Role of sociality in the response of killer whales to an additive mortality event.

In highly social top predators, group living is an ecological strategy that enhances individual fitness, primarily through increased foraging success. Additive mortality events across multiple social groups in populations may affect the social structure, and therefore the fitness, of surviving individuals. This hypothesis was examined in a killer whale () population that experienced a 7-y period of severe additive mortality due to lethal interactions with illegal fishing vessels.

Evidence of deep-sea interactions between toothed whales and longlines.

Toothed whales (odontocetes) feeding on fish caught on hooks in longline fisheries is a growing issue worldwide. The substantial impacts that this behaviour, called depredation, can have on the fishing economy, fish stocks and odontocetes populations, raise a critical need for mitigation solutions to be developed. However, information on when, where and how odontocete depredation occurs underwater is still limited, especially in demersal longline fisheries (fishing gear set on the seafloor).

Commercial fishing patterns influence odontocete whale-longline interactions in the Southern Ocean.

The emergence of longline fishing around the world has been concomitant with an increase in depredation-interactions by odontocete whales (removal of fish caught on hooks), resulting in substantial socio-economic and ecological impacts. The extent, trends and underlying mechanisms driving these interactions remain poorly known. Using long-term (2003-2017) datasets from seven major Patagonian toothfish (Dissostichus eleginoides) longline fisheries, this study assessed the levels and inter-annual trends of sperm whale (Physeter macrocephalus) and/or killer whale (Orcinus orca) interactions as proportions of fishing time (days) and fishing area (spatial cells).

Killer whale () interactions with blue-eye trevalla () longline fisheries.

Over the past five decades, marine mammal interactions with fisheries have become a major human-wildlife conflict globally. The emergence of longline fishing is concomitant with the development of depredation-type interactions i.e.