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Historical reconstruction of the population dynamics of southern right whales in the southwestern Atlantic Ocean. Sci Rep 2022; 12:3324. [PMID: 35228635 PMCID: PMC8885757 DOI: 10.1038/s41598-022-07370-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 02/17/2022] [Indexed: 11/09/2022] Open
Abstract
Understanding the recovery of whale populations is critical for developing population-management and conservation strategies. The southern right whale (SRW) Eubalena australis was one of the baleen whale species that has experienced centuries of exploitation. We assess here for the first time the population dynamics of the SRW from the southwestern Atlantic Ocean at the regional level to measure numerically the effect of whaling and estimate the population trend and recovery level after depletion. We reconstructed the catch history of whaling for the period 1670-1973 by an extensive review of different literature sources and developed a Bayesian state-space model to estimate the demographic parameters. The population trajectory indicated that the pre-exploitation abundance was close to 58,000 individuals (median = 58,212; 95% CI = 33,329-100,920). The abundance dropped to its lowest abundance levels in the 1830s when fewer than 2,000 individuals remained. The current median population abundance was estimated at 4,742 whales (95% CI = 3,853-6,013), suggesting that the SRW population remains small relative to its pre-exploitation abundance (median depletion P2021 8.7%). We estimated that close to 36% of the SRW population visits the waters of the Península Valdés, the main breeding ground, every year. Our results provide insights into the severity of the whaling operation in the southwestern Atlantic along with the population´s response at low densities, thus contributing to understand the observed differences in population trends over the distributional range of the species worldwide.
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Zerbini AN, Adams G, Best J, Clapham PJ, Jackson JA, Punt AE. Assessing the recovery of an Antarctic predator from historical exploitation. ROYAL SOCIETY OPEN SCIENCE 2019; 6:190368. [PMID: 31824687 PMCID: PMC6837233 DOI: 10.1098/rsos.190368] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 09/23/2019] [Indexed: 06/01/2023]
Abstract
The recovery of whale populations from centuries of exploitation will have important management and ecological implications due to greater exposure to anthropogenic activities and increasing prey consumption. Here, a Bayesian population model integrates catch data, estimates of abundance, and information on genetics and biology to assess the recovery of western South Atlantic (WSA) humpback whales (Megaptera novaeangliae). Modelling scenarios evaluated the sensitivity of model outputs resulting from the use of different data, different model assumptions and uncertainty in catch allocation and in accounting for whales killed but not landed. A long period of exploitation drove WSA humpback whales to the brink of extinction. They declined from nearly 27 000 (95% PI = 22 800-33 000) individuals in 1830 to only 450 (95% PI = 200-1400) whales in the mid-1950s. Protection led to a strong recovery and the current population is estimated to be at 93% (95% PI = 73-100%) of its pre-exploitation size. The recovery of WSA humpback whales may result in large removals of their primary prey, the Antarctic krill (Euphausia superba), and has the potential to modify the community structure in their feeding grounds. Continued monitoring is needed to understand how these whales will respond to modern threats and to climate-driven changes to their habitats.
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Affiliation(s)
- Alexandre N. Zerbini
- Marine Mammal Laboratory, Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 7600 Sand Point Way NE, Seattle, WA 98115-6349, USA
- Marine Ecology and Telemetry Research, 2468 Camp McKenzie Tr NW, Seabeck, WA 98380, USA
- Cascadia Research Collective, 218 ½ 4th Avenue W, Olympia, WA 98501, USA
- Instituto Aqualie, Avenida Doutor Paulo Japiassú Coelho 714, Sala 202, Juiz de Fora, MG, Brazil
| | - Grant Adams
- School of Aquatic and Fishery Sciences, University of Washington, 1122 NE Boat Street, Seattle, WA 98105, USA
| | - John Best
- Quantitative Ecology and Resource Management, University of Washington, 1503 NE Boat Street, Seattle, WA 98105, USA
| | | | | | - Andre E. Punt
- School of Aquatic and Fishery Sciences, University of Washington, 1122 NE Boat Street, Seattle, WA 98105, USA
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Horbowy J, Tomczak MT. Extension of biomass estimates to pre-assessment periods using density dependent surplus production approach. PLoS One 2017; 12:e0186830. [PMID: 29131850 PMCID: PMC5683571 DOI: 10.1371/journal.pone.0186830] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 09/29/2017] [Indexed: 11/18/2022] Open
Abstract
Biomass reconstructions to pre-assessment periods for commercially important and exploitable fish species are important tools for understanding long-term processes and fluctuation on stock and ecosystem level. For some stocks only fisheries statistics and fishery dependent data are available, for periods before surveys were conducted. The methods for the backward extension of the analytical assessment of biomass for years for which only total catch volumes are available were developed and tested in this paper. Two of the approaches developed apply the concept of the surplus production rate (SPR), which is shown to be stock density dependent if stock dynamics is governed by classical stock-production models. The other approach used a modified form of the Schaefer production model that allows for backward biomass estimation. The performance of the methods was tested on the Arctic cod and North Sea herring stocks, for which analytical biomass estimates extend back to the late 1940s. Next, the methods were applied to extend biomass estimates of the North-east Atlantic mackerel from the 1970s (analytical biomass estimates available) to the 1950s, for which only total catch volumes were available. For comparison with other methods which employs a constant SPR estimated as an average of the observed values, was also applied. The analyses showed that the performance of the methods is stock and data specific; the methods that work well for one stock may fail for the others. The constant SPR method is not recommended in those cases when the SPR is relatively high and the catch volumes in the reconstructed period are low.
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Affiliation(s)
- Jan Horbowy
- National Marine Fisheries Research Institute, Gdynia, Poland
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Jackson JA, Carroll EL, Smith TD, Zerbini AN, Patenaude NJ, Baker CS. An integrated approach to historical population assessment of the great whales: case of the New Zealand southern right whale. ROYAL SOCIETY OPEN SCIENCE 2016; 3:150669. [PMID: 27069657 PMCID: PMC4821268 DOI: 10.1098/rsos.150669] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2015] [Accepted: 02/16/2016] [Indexed: 05/06/2023]
Abstract
Accurate estimation of historical abundance provides an essential baseline for judging the recovery of the great whales. This is particularly challenging for whales hunted prior to twentieth century modern whaling, as population-level catch records are often incomplete. Assessments of whale recovery using pre-modern exploitation indices are therefore rare, despite the intensive, global nature of nineteenth century whaling. Right whales (Eubalaena spp.) were particularly exploited: slow swimmers with strong fidelity to sheltered calving bays, the species made predictable and easy targets. Here, we present the first integrated population-level assessment of the whaling impact and pre-exploitation abundance of a right whale, the New Zealand southern right whale (E. australis). In this assessment, we use a Bayesian population dynamics model integrating multiple data sources: nineteenth century catches, genetic constraints on bottleneck size and individual sightings histories informing abundance and trend. Different catch allocation scenarios are explored to account for uncertainty in the population's offshore distribution. From a pre-exploitation abundance of 28 800-47 100 whales, nineteenth century hunting reduced the population to approximately 30-40 mature females between 1914 and 1926. Today, it stands at less than 12% of pre-exploitation abundance. Despite the challenges of reconstructing historical catches and population boundaries, conservation efforts of historically exploited species benefit from targets for ecological restoration.
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Affiliation(s)
- Jennifer A. Jackson
- British Antarctic Survey, NERC, High Cross, Madingley Road, Cambridge, UK
- Author for correspondence: Jennifer A. Jackson e-mail:
| | - Emma L. Carroll
- Scottish Oceans Institute, School of Biology, University of St Andrews, Fife, St Andrews KY16 8LB, UK
| | | | - Alexandre N. Zerbini
- National Marine Mammal Laboratory, Alaska Fisheries Science Center, NOAA Fisheries, 7600 Sand Point Way NE, Seattle, WA 98115-6349, USA
- Cascadia Research Collective, 218 1/2 W 4th Ave, Olympia, WA 98501, USA
- Instituto Aqualie, Av. Dr Paulo Japiassu Coelho, 714, Sala 206, Juiz de Fora, Minas Gerais, Brazil
| | | | - C. Scott Baker
- School of Biological Sciences, University of Auckland, Auckland 1010, New Zealand
- Marine Mammal Institute and Department of Fisheries and Wildlife, Hatfield Marine Science Center, Oregon State University, Newport, OR 97365, USA
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Sato K. Publishing ethics in Population Ecology. POPUL ECOL 2015. [DOI: 10.1007/s10144-014-0465-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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