Steller Sea Lion (Eumetopias jubatus) Response to Non-lethal Hazing at Bonneville Dam

Protected Steller sea lions (Eumetopias jubatus) aggregate at Bonneville Dam on the Columbia River and prey upon multiple species of endangered salmon ascending the river. Hazing is a non-lethal activity designed to repel sea lions that includes aversive auditory and physical stimuli to deter animals from an area and has been employed with sea lion—fisheries interactions for more than 40 years but sea lion responses to hazing through time is not well-documented. We observed the behavior of Steller sea lions in periods with and without hazing during two spring Chinook salmon passage seasons to evaluate: (1) what effect hazing had on the number of animals present and their foraging behavior, and (2) whether they habituated to hazing. We found that hazing temporarily reduced the number of Steller sea lions, but only when actively hazed. During hazing, Steller sea lions were more likely to move away from hazers on the dam, decreased their foraging, and increased their time investigating the environment. However, these effects were temporary; their behavior returned to initial observation levels once hazing ceased. Furthermore, their responsiveness to hazing declined throughout the season, indicating habituation and raising concern for the application and long-term efficacy of hazing in managing predation on endangered salmon.

Cetacean mortality due to interactions with fisheries and marine litter ingestion in the Croatian part of the Adriatic Sea from 1990 to 2019

Various anthropogenic threats negatively influence the survival of cetaceans in all world seas. Thanks to a long-running marine mammal surveillance program, we are able to report the results of a detailed analysis of the influence of cetacean-fisheries interactions and marine litter ingestion on cetacean mortality in the Croatian part of the Adriatic Sea over the last three decades. The total number of dead cetaceans was 459, and included 334 bottlenose dolphins (Tursiops truncatus), 40 striped dolphins (Stenella coeruleoalba), ten Risso’s dolphins (Grampus griseus), six Cuvier’s beaked whales (Ziphius cavirostris) and four fin whales (Balaenoptera physalus). Three hundred of them were examined postmortally. Cetacean-fisheries interaction occurred frequently in the Adriatic Sea, being detected in 96 (20.9%) of the recorded cases. Bycatch was the most abundant cetacean-fisheries interaction, with 66 (14.4%) cases recorded. Good nutritional condition and evidence of recent feeding were the most common findings recorded in bycatch cases, followed by persistent froth in the airways, edematous lungs, bruises and an amputated fluke or tail. Cetacean-fisheries interactions other than bycatch affected 30 animals and included larynx strangulations, long-term tail entanglement and fishing gear in the stomach. Ingestion of marine litter that was not related to fisheries was recorded in four animals. This study reveals the considerable negative anthropogenic influence on cetaceans in the Adriatic Sea, especially the bottlenose dolphin that is considered to be the most numerous cetacean species therein, and demonstrates the need for the urgent development of a cetacean bycatch reduction program. Finally, it also shows the importance of sustaining national surveillance programs to gain scientifically based knowledge important for cetacean protection and prospects for their long-term survival.

Differences in foraging habitat result in contrasting fisheries interactions in two albatross populations

Albatrosses attend fishing boats to feed on fishing discards but are often at risk of accidental bycatch. To examine whether populations (same species) and sexes differ in their overlap with fisheries due to differences in habitat use, we combined the use of recently developed loggers equipped with GPS and boat radar detectors with Automatic Identification System (AIS) data. Our study indicates that incubating wandering albatrosses Diomedea exulans from Crozet and Kerguelen foraged in different habitats although the duration of trips was similar. Both female and male Kerguelen birds took advantage of the large and productive surrounding shelf, whereas Crozet birds used the small shelf around the islands to a lesser extent. In Crozet, there was segregation between males and females, the latter favouring deeper and warmer waters. The 2 strategies of habitat use led to different overlap and attraction to boats, with Kerguelen birds encountering and attending boats for longer and at closer proximity to the colony than Crozet birds. Crozet females encountered boats at greater distances from the colony than males. Because of their different habitat use and foraging outside exclusive economic zones (EEZ) and further from the colony, Crozet birds attended more non-declared boats (without AIS) than Kerguelen birds. Albatrosses were more attracted by fisheries than cargo vessels and were especially attracted by fishing discards that led them to attend vessels for longer periods for both sexes and populations. The differences found between populations and individuals in terms of habitat specialization and encounter rate of fisheries should be considered for future assessments of risk of bycatch.

Interaction between dolphins and coastal fisheries and using acoustic deterrent in reducing of interaction

This study was conducted at the Unye-Ordu coasts of the South-eastern Black Sea, from May 2015 and February 2017, to investigate the frequency of dolphins-bottom gillnet fisheries interactions, the role of using acoustic deterrent in reducing the damage inflicted by the dolphins to the gillnets and to the fish caught in the gillnets. For this purpose, two gillnet sets with similar technical and equipment characteristics were prepared. While one of the groups had acoustic deterrent (active group), the other did not have acoustic deterrent (control group). In the study were used Future Oceans (70 kHz) deterrent. During the study, in only 3 of the 65 fishing trials have determined the interaction of dolphins with gillnets. It was determined that the number of holes in the gillnets caused by the dolphins was 36.3% less in the nets with acoustic deterrent than the control nets. On the other hand, the CPUE value of the whiting was estimated as 2.01 ± 0.23 kg km-1 s-1 in the gillnets with acoustic deterrent and 1.97 ± 0.24 kg km-1 s-1 in the control nets. These results showed that the use of acoustic deterrent does not have a negative effect on the catch of whiting caught in the gillnets.

On conducting management-relevant mechanistic science for upriver migrating adult Pacific salmon

Pacific salmon undertake iconic homeward migrations where they move from ocean feeding grounds to coastal rivers where they return to natal spawning sites. However, this migration is physiologically challenging as fish have to navigate past predators, nets, hooks, and dams while dealing with variable flows, warm water temperatures, and pathogens. These challenges often interact in synergistic ways that can sometimes lead to migration failure. The conservation physiology toolbox has led to new understanding of how salmon deal with different challenges with a goal of generating management-relevant science. Given the sensitivity of Pacific salmon to warm temperatures, much research has focused on identifying thermal thresholds. In addition, physiology has informed the development of methods for recovering fish that are exhausted from fisheries interactions and for enhancing passage success at fishways. These successes have arisen in part due to the extent to which we partnered with fisheries managers and other stakeholders to ensure that we were conducting relevant research.

Bacteriological and histopathological findings in cetaceans that stranded in the Philippines from 2017 to 2018

The relatively high frequency of marine mammal stranding events in the Philippines provide many research opportunities. A select set of stranders (n=21) from 2017 to 2018 were sampled for bacteriology and histopathology. Pertinent tissues and bacteria were collected from eight species (i.e. Feresa attenuata, Kogia breviceps, Globicephala macrorhynchus, Grampus griseus, Lagenodelphis hosei, Peponocephala electra, Stenella attenuata and Stenella longirostris) and were subjected to histopathological examination and antibiotic resistance screening, respectively. Lesions that were observed in tissues of 19 cetaceans include congestion, hemorrhage, edema, hemosiderosis, glomerulopathy, Zenker’s necrosis, atrophy, atelectasis, and parasitic cysts. These lesions may be associated with factors possibly contributing to the death, debility, and stress of the animals during their strandings. On the other hand, the resistance profiles of 24 bacteria (belonging to genera Escherichia, Enterobacter, Klebsiella, Proteus, and Shigella) that were isolated from four cetaceans were determined using 18 antibiotics. All 24 isolates were resistant to at least one antibiotic class, and 79.17% were classified as multiple antibiotic resistant (MAR). The MAR index values of isolates ranged from 0.06 to 0.39 with all the isolates resistant to erythromycin (100%; n=24) and susceptible to imipenem, doripenem, ciprofloxacin, chloramphenicol, and gentamicin (100%; n=24). The resistance profiles of these bacteria can be used as basis for selecting antibiotics needed in the medical management of stranded cetaceans that need to be rehabilitated. Overall, the histopathological and bacteriological findings of the study demonstrate the challenges faced by cetacean species in the wild, such as but not limited to, biological pollution through land-sea movement of effluents, fisheries interactions, and anthropogenic activities.

A veterinary perspective on the conservation physiology and rehabilitation of sea turtles

Sea turtle populations are threatened globally due to anthropogenic and natural factors, including fisheries interactions, watercraft strike, hunting, habitat loss, pollution, climate change, and severe weather. Injured and ill sea turtles are often evaluated by wildlife rehabilitation centres, and many sea turtles can be returned to the wild after rehabilitation. Physiological evaluation of injured and ill sea turtles has revealed life-threatening physiological dysfunction such as acidosis, hypoxia, hypercarbia, dehydration, and hyperkalaemia. Recognition and management of such conditions has improved the outcome for these patients. In addition to clinical advancement, veterinary evaluation has improved our understanding of general sea turtle biology, and increased the safety of procedures such as anaesthesia and laparoscopy. These modalities, combined with emerging biotelemetry technologies, will continue to improve our understanding of sea turtle ecology and conservation physiology.

Spatiotemporal analyses of tracking data reveal fine-scale, daily cycles in seabird–fisheries interactions

Human fisheries provide scavengers with abundant and predictable feeding opportunities that may schedule their behavioural patterns. Using miniaturized global positioning system (GPS) tracking technology, we evaluated how Audouin’s gull (Ichthyaetus audouinii), a Mediterranean endemic seabird that makes extensive use of feeding opportunities provided by fisheries, co-occurred (i.e. presumably interacted) with the most important fishing fleets operating off the NE Iberian Peninsula (i.e. diurnal trawlers and nocturnal purse seiners), both in space and time. Results showed that individuals were able to adapt their distribution and activity patterns to the scheduled routines of these fisheries. Waveform analyses based on co-occurring positions revealed that most interactions with trawlers occurred during the afternoon (16:00 h GMT + 1) when discarding occurs as vessels return to port. In contrast, gull-purse seiner interactions largely occurred at night (between 02:00 and 04:00 h) coinciding with the setting and hauling of the nets. Moreover, we found an individual component in seabird–fishery interactions, showing that there may be differential use of fisheries by individuals within the population. In addition to implications for our understanding of the behavioural ecology of this species, these results may have important management implications, particularly under the current European Union Common Fisheries Policy scenario of largely restricting discards.