[MARMAM] New article on foraging behaviour of sperm whales in a submarine canyon
Dear all We are happy to announce our recent publication: Diverse foraging strategies by a marine top predator: sperm whales exploit pelagic and demersal habitats in the Kaikoura submarine canyon. Marta Guerra, Leigh Hickmott, Julie van der Hoop, Will Rayment, Eva Leunissen, Elizabeth Slooten, Michael Moore. (2017). Deep-Sea Research Part I, 128: 98-108. Abstract: The submarine canyon off Kaikoura (New Zealand) is an extremely productive deep-sea habitat, and an important foraging ground for male sperm whales (Physeter macrocephalus). We used high-resolution archival tags to study the diving behaviour of sperm whales, and used the echoes from their echolocation sounds to estimate their distance from the seafloor. Diving depths and distance above the seafloor were obtained for 28 dives from six individuals. Whales foraged at depths between 284 and 1433 m, targeting mesopelagic and demersal prey layers. The majority of foraging buzzes occurred within one of three vertical strata: within 50 m of the seafloor, mid-water at depths of 700-900 m, and mid-water at depths of 400-600 m. Sperm whales sampled during this study performed more demersal foraging than that reported in any previous studies - including at Kaikoura in further inshore waters. This suggests that the extreme benthic productivity of the Kaikoura Canyon is reflected in the trophic preferences of these massive top predators. We found some evidence for circadian patterns in the foraging behaviour of sperm whales, which might be related to vertical movements of their prey following the deep scattering layer. We explored the ecological implications of the whales' foraging preferences on their habitat use, highlighting the need for further research on how submarine canyons facilitate top predator hotspots. A pdf can be obtained through this link: https://authors.elsevier.com/a/1Vomf3RueHM4lY? Or email marta.gue...@otago.ac.nz for a paper request. Best wishes, Marta ? Marta Guerra PhD candidate Department of Marine Science University of Otago, Dunedin Aotearoa - New Zealand ph: +64 226784245 ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
[MARMAM] New publication: impact of earthquakes on habitat use by sperm whales
Dear MARMAM subscribers, My colleagues and I would like to announce the publication of an article on the impact of earthquakes on habitat use by sperm whales, published in Deep Sea Research Part I. Please see abstract below. The article can be accessed via https://doi.org/10.1016/j.dsr.2020.103226 (subscription only), or you can email me at marta.gue...@otago.ac.nz for a copy of the pdf. Cheers, Marta Guerra 'Changes in habitat use by a deep-diving predator in response to a coastal earthquake' Marta Guerra, Stephen Dawson, Amandine Sabadel, Elizabeth Slooten, Tamlyn Somerford, Roger Williams, Lucy Wing, William Rayment. Abstract: Earthquakes can significantly impact ecosystem function and survivability of marine organisms, however their effect on marine predators remains unknown. In November 2016, a 7.8 magnitude earthquake triggered a ‘canyon flushing’ event in the submarine canyon of Kaikōura (New Zealand), a year-round foraging ground for sperm whales (Physeter macrocephalus). Underwater landslips and turbidity currents caused significant changes to the seafloor and removed large quantities of benthic biomass from the canyon. To investigate the potential impact of the earthquake on habitat use by sperm whales, we used a multi-year dataset to quantify changes in their behaviour, foraging distribution and use of food resources before and after the earthquake. The diving locations and behaviour of individual whales were recorded during summer and winter from January 2014 to January 2018, and samples of sloughed skin were collected for bulk and amino acid specific stable isotope analyses. While blow rates remained unchanged, the mean surface interval between dives was 25% longer for about one year after the earthquake, potentially reflecting increased effort searching for prey. Stable isotope ratios of sperm whale skin provided no evidence for change in diet. However, significant changes in the distribution of core foraging areas indicated shifts in habitat use for at least one year, potentially driven by changes in the seafloor and prey availability following the canyon flushing. Overall, our observations suggested that the earthquake caused alterations in the foraging patterns of sperm whales over a period of at least 12 months. This was the first study to quantify the impact of an earthquake on a marine mammal population, providing new insights into how top predators react and adapt to large-scale events of natural disturbance. ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
[MARMAM] New publication on foraging ecology of sperm whales based on stable isotope analyses
Dear MARMAM subscribers, My colleagues and I would like to announce the publication of the following article in Marine Ecology Progress Series: *'Stable isotope analyses reveal seasonal and inter-individual variation in the foraging ecology of sperm whales'* Marta Guerra, Lucy Wing, Stephen Dawson, William Rayment Abstract: Studying inter-individual variation in foraging by top predators is key for understanding the ecology of their populations, while knowledge of seasonal variability in foraging helps explain temporal changes in habitat use and ecological role. We investigated the inter-individual and seasonal differences in stable isotope ratios of sperm whales *(Physeter macrocephalus)* in the temperate foraging ground of the Kaikōura Canyon, New Zealand. Isotope ratios of carbon and nitrogen were measured in 107 samples of sloughed skin from 37 individual males with a wide range of residency patterns and body lengths, sampled over four summers and three winters. Variability in individual isotope ratios was analysed with generalised additive mixed models. The whales’ residency patterns, but not body size, accounted for most heterogeneity of δ13C and δ15N. Specifically, whales that visited Kaikōura occasionally had more diverse and lower isotope ratios than more frequent visitors (by* ca. *-1‰ δ13C and -2‰ δ15N), likely reflecting a range of foraging habitats further offshore and/or south of Kaikōura Canyon. We suggest that these patterns reflect differences in large-scale foraging patterns within the population. In addition, whales sampled in winter had significantly lower values of δ13C than whales sampled in summer (by* ca. *-0.5‰), indicating seasonal differences in the use of food resources. Our results provide new insights into foraging patterns of sperm whales, and highlight the value of accounting for individual differences in the ecology of top predators. The article can be accessed via https://doi.org/10.3354/meps13255 (subscription only), or you can email me at marta.gue...@otago.ac.nz for a copy of the pdf. Best wishes, Marta Guerra ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
[MARMAM] New publication: Lessons from research and management of cetacean tourism in New Zealand
Dear MARMAM subscribers, On behalf of my colleagues, I would like to announce the publication of our article 'Looking back to move forward: lessons from three decades of research and management of cetacean tourism in New Zealand', recently published in Frontiers in Marine Science. The article can be accessed via https://doi.org/10.3389/fmars.2021.624448 (open access), or you can also email me at marta.gue...@otago.ac.nz for a copy of the pdf. Best wishes, Marta 'Looking back to move forward: lessons from three decades of research and management of cetacean tourism in New Zealand' Maddalena Fumagalli, Marta Guerra, Tom Brough, William Carome, Rochelle Constantine, James Higham, Will Rayment, Elisabeth Slooten, Karen Stockin, Steve Dawson. Abstract: Cetacean tourism in Aotearoa New Zealand is now over 30 years old and has experienced substantial growth in visitor numbers and operations. The industry is remarkably diverse, targeting several dolphin and whale species, and encompassing varied habitats in coastal waters, fiords and submarine canyons. The knowledge and experience collected over these past 30 years has both advanced the global understanding of cetacean tourism, and influenced scientific practices for its study and management. Here we review the approaches taken in quantifying the impact of cetacean tourism in New Zealand, and critically assess the efficacy of the research and management strategies adopted. We place particular focus on the Bay of Islands, Hauraki Gulf, Kaikoura, Akaroa and Fiordland, areas that include the oldest, and longest studied industries nationally. We propose a set of best research practices, expose the most notable knowledge gaps and identify emerging research questions. Drawing on perspectives from the natural and social sciences, we outline the key determinants of failure and success in protecting cetacean populations from the detrimental impact of tourism. We suggest four golden rules for future management efforts: (1) acknowledge cetacean tourism as a sub-lethal anthropogenic stressor to be managed with precaution, (2) apply integrated and adaptive site- and species-specific approaches, (3) fully conceptualize tourism within its broader social and ecological contexts, and (4) establish authentic collaborations and engagement with the local community. Lastly, we forecast upcoming challenges and opportunities for research and management of this industry in the context of global climate change. Despite New Zealand's early establishment of precautionary legislation and advanced tourism research and management approaches, we detected flaws in current schemes, and emphasize the need for more adaptive and comprehensive strategies. Cetacean tourism remains an ongoing challenge in New Zealand and globally. ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
[MARMAM] New publication on fine-scale foraging ecology of sperm whales
Dear MARMAM subscribers, My colleagues and I would like to announce the publication of the following article in Marine Mammal Science: *Fine-scale habitat use of foraging sperm whales is driven by seafloor topography and water column structure* Marta Guerra, Stephen M. Dawson, Tamlyn R. Somerford, Elizabeth Slooten, William J. Rayment Abstract: Knowledge of the spatial distribution and habitat preferences of marine top-predators is essential for monitoring their populations. The summertime abundance of male sperm whales (parāoa, *Physeter macrocephalus*) at the Kaikōura Canyon (New Zealand) has almost halved over the last three decades, possibly reflecting a shift in distribution away from this foraging ground. To better understand the seasonal drivers of habitat use by sperm whales, we recorded presence and absence locations of foraging whales during acoustic-visual surveys, in conjunction with water-column oceanographic sampling. Season-specific generalized additive models (GAM) indicated that whale distribution was best predicted by seafloor depth, thermal stratification in the water-column, and slope gradient and orientation. Habitat use differed between summer and winter, consistent with patterns in diving behavior and stable isotope ratios, suggesting seasonal fluctuations in prey targeted by sperm whales. Our results advance understanding of fine-scale habitat use by sperm whales, with new insights into the ecological drivers of seasonal fluctuations in foraging distribution. Our study demonstrates the importance of quantifying water-column processes in the study of habitat preferences by deep-diving predators. We also identify thermal stratification as an oceanographic feature susceptible to climate change, which could contribute to the decline in sperm whale abundance at Kaikōura. The article can be accessed via *http://doi.org/10./mms.12881 <http://doi.org/10./mms.12881>* (subscription), or you can email me at marta.gue...@otago.ac.nz for a copy of the pdf. Best wishes, Marta Guerra ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
[MARMAM] New paper on the management of tourism and dolphin-boat interactions
?Dear all We are happy to announce our recent publication: Boat-based tourism and bottlenose dolphins in Doubtful Sound, New Zealand: The role of management in decreasing dolphin-boat interactions. M. Guerra and S. M. Dawson (2016) Tourism Management 57: 3-9. For a PDF please follow this link: http://www.sciencedirect.com/science/article/pii/S0261517716300802 or email marta.gue...@otago.ac.nz. Abstract: Indirect non-lethal effects of wildlife tourism have the potential to compromise the long-term health of animal populations. While appropriate management of impacts is clearly necessary, such management is rarely reported to be effective. Doubtful Sound (New Zealand) has boat-based scenic cruises running year-round. This fjord is also home to an endangered population of bottlenose dolphins, a natural asset for the local tourism industry. A voluntary code of management (COM) was implemented in 2008 to alleviate vessel impacts, establishing guidelines to leave dolphin encounters to chance and restricting vessel traffic in areas of critical habitat. The frequency and duration of interactions decreased substantially since the implementation of the COM. This evidence shows that a science-based voluntary agreement has the potential to mitigate tourism impacts. Nevertheless, due to the small size of the population and its history of low calf survival, a precautionary approach is necessary to further reduce current anthropogenic impacts. Best wishes, Marta Guerra ? PhD candidate Department of Marine Science University of Otago, Dunedin Aotearoa - New Zealand ph: +64 226784245 ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
