Isotopic evidence of a wide spectrum of feeding strategies in Southern hemisphere humpback whale baleen records

Our current understanding of Southern hemisphere humpback whale (Megaptera novaeangliae) ecology assumes high-fidelity feeding on Antarctic krill in Antarctic waters during summer, followed by fasting during their annual migration to and from equatorial breeding grounds. An increase in the number of reported departures from this feeding/fasting model suggests that the current model may be oversimplified or, alternatively, undergoing contemporary change. Information about the feeding and fasting cycles of the two Australian breeding populations of humpback whales were obtained through stable isotope analysis of baleen plates from stranded adult individuals. Comparison of isotope profiles showed that individuals from the West Australian breeding population strongly adhered to the classical feeding model. By contrast, East Australian population individuals demonstrated greater heterogeneity in their feeding. On a spectrum from exclusive Antarctic feeding to exclusive feeding in temperate waters, three different strategies were assigned and discussed: classical feeders, supplemental feeders, and temperate zone feeders. Diversity in the interannual feeding strategies of humpback whales demonstrates the feeding plasticity of the species, but could also be indicative of changing dynamics within the Antarctic sea-ice ecosystem. This study presents the first investigation of trophodynamics in Southern hemisphere humpback whales derived from baleen plates, and further provides the first estimates of baleen plate elongation rates in the species

Radiocarbon as a novel tracer of extra-Antarctic feeding in Southern Hemisphere Humpback Whales

Bulk stable isotope analysis provides information regarding food web interactions, and has been applied to several cetacean species for the study of migration ecology. One limitation in bulk stable isotope analysis arises when a species, such as Southern hemisphere humpback whales, utilises geographically distinct food webs with differing isotopic baselines. Migrations to areas with different baselines can result in isotopic changes that mimic changes in feeding relations, leading to ambiguous food web interpretations. Here, we demonstrate the novel application of radiocarbon measurement for the resolution of such ambiguities. Radiocarbon was measured in baleen plates from humpback whales stranded in Australia between 2007 and 2013, and in skin samples collected in Australia and Antarctica from stranded and free-ranging animals. Radiocarbon measurements showed lower values for Southern Ocean feeding than for extra-Antarctic feeding in Australian waters. While the whales mostly relied on Antarctic-derived energy stores during their annual migration, there was some evidence of feeding within temperate zone waters in some individuals. This work, to our knowledge, provides the first definitive biochemical evidence for supplementary feeding by southern hemisphere humpback whales within temperate waters during migration. Further, the work contributes a powerful new tool (radiocarbon) for tracing source regions and geographical feeding

Effectiveness of mitigation measures to reduce interactions between commercial fishing gear and whales

Effectiveness of mitigation measures to reduce interactions between commercial fishing gear and whales. Objectives: 1. Start to collect additional information required to determine the spatial and temporal extent of migrating whales and how this overlaps with commercial fishing gear. 2. Examine the effectiveness of potential gear modifications to the float rigs of fishing pots/traps to reduce their likelihood of entangling whales

Mitigation measures to reduce entanglements of migrating whales with commercial fishing gear

The West Coast Rock Lobster Managed Fishery (WCRLMF) transitioned to a quota based fishery, and year-round fishing, which corresponded with a spike in whale entanglements in 2013. This presented industry with a challenging social issue, to reduce entanglements without impacting on the financial benefits that the shift to year-round quota fishing had afforded

Multiple drivers of decline in the global status of freshwater crayfish (Decapoda: Astacidea)

International audienceRates of biodiversity loss are higher in freshwater ecosystems than in most terrestrial or marine ecosystems, making freshwater conservation a priority. However, prioritization methods are impeded by insufficient knowledge on the distribution and conservation status of freshwater taxa, particularly invertebrates. We evaluated the extinction risk of the world's 590 freshwater crayfish species using the IUCN Categories and Criteria and found 32% of all species are threatened with extinction. The level of extinction risk differed between families, with proportionally more threatened species in the Parastacidae and Astacidae than in the Cambaridae. Four described species were Extinct and 21% were assessed as Data Deficient. There was geographical variation in the dominant threats affecting the main centres of crayfish diversity. The majority of threatened US and Mexican species face threats associated with urban development, pollution, damming and water management. Conversely, the majority of Australian threatened species are affected by climate change, harvesting, agriculture and invasive species. Only a small proportion of crayfish are found within the boundaries of protected areas, suggesting that alternative means of long-term protection will be required. Our study highlights many of the significant challenges yet to come for freshwater biodiversity unless conservation planning shifts from a reactive to proactive approach

The Digital Transformation of Search and Recombination in the Innovation Function: Tensions and an Integrative Framework*

Search and recombination are important mechanisms in the creativity phase of innovation. Digital transformation and the resulting pervasive digitalization of the innovation function have often been associated with increasing possibilities for search and recombination. In this paper, by systematically integrating the search and recombination literature with the literature on digitalization, we demonstrate that digitalization may engender new idiosyncratic tensions in the organizational antecedents of search and recombination and, by implication, in their likely outcomes. We propose that, depending on the interactions among the idiosyncratic tensions identified herein, knowledge recombination might spur very different outcomes, including knowledge layering, knowledge integration, knowledge grafting, or even no recombination at all (which we label “search for the sake of search”). These outcomes may not always be the initially planned desired outcomes. Finally, we provide implications of our integrative framework pertaining to product development and to organizing for innovation

Mitigation measures to reduce entanglements of migrating whales with commercial fishing gear

The West Coast Rock Lobster Managed Fishery (WCRLMF) transitioned to a quota based fishery, and year-round fishing, which corresponded with a spike in whale entanglements in 2013. This presented industry with a challenging social issue, to reduce entanglements without impacting on the financial benefits that the shift to year-round quota fishing had afforded