Marine Mammal Science最新文献

{"title":"Exploring habitat use and movement patterns of humpback whales in a reoccupation area off Brazil: A comparison with the Abrolhos Bank","authors":"Bianca M. Righi,&nbsp;Julio E. Baumgarten,&nbsp;Maria Emilia Morete,&nbsp;Rafaela C. F. Souza,&nbsp;Milton C. C. Marcondes,&nbsp;Renata S. Sousa-Lima,&nbsp;Niel N. Teixeira,&nbsp;Fernanda A. S. Tonolli,&nbsp;Maria Isabel C. Gonçalves","doi":"10.1111/mms.13139","DOIUrl":"10.1111/mms.13139","url":null,"abstract":"<p>After the worldwide moratorium on whaling, humpback whale populations began to recover, reoccupying former areas of use, as also observed on the Brazilian coast. Abrolhos Bank represents the area of greatest humpback whale concentration but the number of individuals to the north has increased, as has happened in the region of Serra Grande. To compare relative abundance, habitat use, and movement patterns between a well-established breeding and a reoccupation area, visual monitoring from land-based stations was performed: 160 days in the Abrolhos Archipelago located on the Abrolhos Bank and 133 days in Serra Grande in 2014, 2015, 2018, and 2019. While relative abundance varied annually in the Abrolhos Archipelago, it gradually increased in Serra Grande, surpassing the number registered in Abrolhos in 2019. Group composition frequency was similar between areas except for mother and calf accompanied by one or more escorts, which were more frequent in Abrolhos. Despite similar movement speed and linearity values, whales in Serra Grande had a higher reorientation rate. Monitoring different areas occupied by this population supports decisions about spatial management of the Brazilian coast in relation to the implementation of anthropogenic activities, especially in areas where whales have recently returned to occupy.</p>","PeriodicalId":18725,"journal":{"name":"Marine Mammal Science","volume":"40 4","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140971843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Automated body length and body condition measurements of whales from drone videos for rapid assessment of population health","authors":"Kevin Charles Bierlich,&nbsp;Sagar Karki,&nbsp;Clara N. Bird,&nbsp;Alan Fern,&nbsp;Leigh G. Torres","doi":"10.1111/mms.13137","DOIUrl":"10.1111/mms.13137","url":null,"abstract":"<p>Monitoring body length and body condition of individuals helps determine overall population health and assess adaptation to environmental changes. Aerial photogrammetry from drone-based videos is a valuable method for obtaining body length and body condition measurements of cetaceans. However, the laborious manual processing of drone-based videos to select frames to measure animals ultimately delays assessment of population health and hinders conservation actions. Here, we apply deep learning methods to expedite the processing of drone-based videos to improve efficiency of obtaining important morphological measurements of whales. We develop two user-friendly models to automatically (1) detect and output frames containing whales from drone-based videos (“DeteX”) and (2) extract body length and body condition measurements from input frames (“XtraX”). We use drone-based videos of gray whales to compare manual versus automated measurements (<i>n</i> = 86). Our results show automated methods reduced processing times by one-ninth, while achieving similar accuracy as manual measurements (mean coefficient of variation &lt;5%). We also demonstrate how these methods are adaptable to other species and identify remaining challenges to help further improve automated measurements in the future. Importantly, these tools greatly speed up obtaining key morphological data while maintaining accuracy, which is critical for effectively monitoring population health.</p>","PeriodicalId":18725,"journal":{"name":"Marine Mammal Science","volume":"40 4","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/mms.13137","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140939994","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Humpback whale (Megaptera novaeangliae) social calls in southern British Columbia","authors":"Zoe A. Molder,&nbsp;William D. Halliday,&nbsp;Rhonda Reidy,&nbsp;Chloe N. Kraemer,&nbsp;Francis Juanes","doi":"10.1111/mms.13138","DOIUrl":"10.1111/mms.13138","url":null,"abstract":"<p>Humpback whale (<i>Megaptera novaeangliae)</i> nonsong vocalizations, or social calls, are much more poorly understood than humpback song. We examined humpback whale social calls from a foraging ground in southern British Columbia (BC) and developed a catalog for humpback social calls in BC. We tagged four humpback whales on the eastern edge of Swiftsure Bank, BC, in early September 2020, with a passive acoustic and movement tag. We manually classified 32 call types in our data set based on comparisons with published classifications of humpback social calls. Many of the calls identified in our data set had similar characteristics to calls from other locations. We also used two statistical classification methods, a cluster analysis and a random forest. The cluster analysis grouped 20 of these call types into four categories, and the random forest classifier was able to accurately classify all 20 call types 87.6% of the time. This study fills a geographical gap of humpback whale social calls on foraging grounds and is a first step towards categorizing the social calls of humpback whales in BC.</p>","PeriodicalId":18725,"journal":{"name":"Marine Mammal Science","volume":"40 4","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/mms.13138","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140939342","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Social structure and site fidelity of an oceanic delphinid: the rough-toothed dolphin (Steno bredanensis) off the southwest Pacific coast of Mexico","authors":"Victoria Pouey-Santalou,&nbsp;Michael Weiss,&nbsp;Eric Angel Ramos,&nbsp;Jeremy J. Kiszka,&nbsp;Raúl Fernando Ramírez Barragán,&nbsp;Andrea Jacqueline García Chavez,&nbsp;Katherina Audley","doi":"10.1111/mms.13136","DOIUrl":"10.1111/mms.13136","url":null,"abstract":"<p>Rough-toothed dolphins (<i>Steno bredanensis</i>) typically inhabit deep oceanic waters from tropical to temperate waters worldwide. However, their ecology and behavior remain poorly understood. We investigated site fidelity and social structure of rough-toothed dolphins using photo-identification data collected between 2014 and 2022 in the continental shelf waters of the southwestern coast of Mexico. A total of 133 groups of rough-toothed dolphins were recorded. Mean group size was 4.9 individuals (<i>SD</i> = 4.5), and dolphins were encountered in waters of a mean depth of 110 m (<i>SD</i> = 188). Of 228 individuals identified, 55% were observed once, 39% were seen between two and four times, and 6% were seen five times or more. Site fidelity analysis suggests three levels of site fidelity: transients, occasional visitors, and regular visitors, which are likely to affect the social structure. Through network analysis, nonrandom social patterns were identified (<i>S</i> = 1.25 ± 0.26) and dolphins exhibited both preferences and avoidances of social partners. Cluster analysis suggested significant divisions within the population (<i>Q</i> = 0.43 ± 0.05). Despite limitations related to sample size and design, this preliminary study suggests that rough-toothed dolphins are best characterized by a fission-fusion society, which is similar to most coastal delphinid populations.</p>","PeriodicalId":18725,"journal":{"name":"Marine Mammal Science","volume":"40 4","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140835343","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Changes in blue whale survival and abundance in the Gulf of California","authors":"Georgina Whittome,&nbsp;John Calambokidis,&nbsp;Annie B. Douglas,&nbsp;Michael Fishbach,&nbsp;Richard Sears,&nbsp;Philip S. Hammond","doi":"10.1111/mms.13132","DOIUrl":"10.1111/mms.13132","url":null,"abstract":"<p>Understanding the drivers of population abundance and distribution is fundamental to ecology and key to informing conservation actions, particularly in endangered species like blue whales (<i>Balaenoptera musculus</i>). Historically, some Eastern North Pacific blue whales have aggregated in the Gulf of California (GoC) each winter. Using photo-identification data collected around Loreto Bay from 1984 to 2020, we analyzed 453 sightings histories using mark-recapture models. Estimated apparent survival (including permanent emigration) decreased from 0.991, 95% CI [0.977, 0.997] in 1985 to 0.889, 95% CI [0.807, 0.939] in 2019. The estimated number of whales using the study area declined from 96 whales, 95% CI [50, 254] in 2012 to 13 whales, 95% CIs [12, 23 and 12, 28] in 2018 and 2019. Abundance of the whole Eastern North Pacific population is slowly increasing, so our results likely reflect declining usage of the GoC. Linear models found a relationship between the number of whales in the GoC and the difference in sea surface temperature between the study area and the Costa Rica Dome wintering area, suggesting that environmental variation could explain variation in blue whale numbers in the GoC. These results highlight the importance of tracking population dynamics as changing environmental conditions affect the range and distribution of populations.</p>","PeriodicalId":18725,"journal":{"name":"Marine Mammal Science","volume":"40 4","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/mms.13132","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140835350","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Foraging behavior and habitat selection of harbor seals (Phoca vitulina vitulina) in the archipelago of Saint-Pierre-and-Miquelon, Northwest Atlantic","authors":"Skye Wynn-Simmonds,&nbsp;Yann Planque,&nbsp;Mathilde Huon,&nbsp;Philip Lovell,&nbsp;Cécile Vincent","doi":"10.1111/mms.13134","DOIUrl":"10.1111/mms.13134","url":null,"abstract":"&lt;p&gt;Studying the foraging behavior of marine top predators is crucial for gaining a comprehensive understanding of their role within the ecosystem and improving management plans around their foraging habitat (Pianka, &lt;span&gt;1976&lt;/span&gt;; Stearns, &lt;span&gt;1992&lt;/span&gt;). Harbor seals (&lt;i&gt;Phoca vitulina vitulina&lt;/i&gt;) are upper-trophic level predators belonging to the phocid family (Teilmann &amp; Galatius, &lt;span&gt;2018&lt;/span&gt;). They are commonly seen as sedentary remaining in coastal waters, although they can occasionally forage offshore in some study sites (Lesage et al., &lt;span&gt;2004&lt;/span&gt;). Throughout their geographic distribution, they inhabit a wide range of habitats, relying heavily on the availability and distribution of their prey in that specific environment (Bowen &amp; Harrison, &lt;span&gt;1996&lt;/span&gt;). As a result, the harbor seal is often regarded as a generalist species with potentially individualistic foraging behavior. Many studies showed that they are benthic feeders with a diet consisting of a wide variety of prey, including various species of benthic and demersal fish, cephalopods, and crustaceans, but can occasionally forage on pelagic prey (Lesage, &lt;span&gt;1999&lt;/span&gt;; Sharples et al., &lt;span&gt;2009&lt;/span&gt;; Thompson, &lt;span&gt;1993&lt;/span&gt;).&lt;/p&gt;&lt;p&gt;In the Northwest Atlantic, harbor seals are generally found in small, isolated groups (Blanchet et al., &lt;span&gt;2021&lt;/span&gt;). They have been documented in the archipelago of Saint-Pierre-and-Miquelon (France) as far back as the 1940s (Templeman, &lt;span&gt;1957&lt;/span&gt;). Despite the absence of prior studies on the foraging behavior of harbor seals in this area, conflicts with recreational fisheries have been noted, and managers have expressed the need to better understand the trophic ecology of these harbor seals. Therefore, this study aimed to characterize the behavior of harbor seals around Saint-Pierre-and-Miquelon by identifying their habitat selection and investigating their foraging behavior at sea (diving behavior and spatio-temporal trends at sea) around the archipelago.&lt;/p&gt;&lt;p&gt;Telemetry data were used to study habitat selection, foraging activity rhythm, and foraging behavior of harbor seals located at Saint-Pierre-and-Miquelon. Ten harbor seals (five females and five males) were captured in September 2019 and September 2020, and fitted with Satellite Relay Data Loggers developed by the Sea Mammal Research Unit (University of St Andrews, UK). The location data and detailed information of individuals are accessible on SEANOE (https://www.seanoe.org/data/00799/91059/). The capture method used was detailed in Vincent et al. (&lt;span&gt;2005&lt;/span&gt;). The Satellite Relay Data Logger (SRDL) includes a GPS that attempts to obtain a location when at the surface, subject to a minimum interval of 20 min. In addition, the tag features a pressure sensor that enables the recording of the maximum depth, duration, and shape of each dive (&lt;−1.5 m) as well as the time and depth delimiting the descent, bottom, and ascent phases ","PeriodicalId":18725,"journal":{"name":"Marine Mammal Science","volume":"40 4","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/mms.13134","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140835340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The long-beaked common dolphin of the eastern Pacific Ocean: Taxonomic status and redescription of Delphinus bairdii","authors":"Thomas A. Jefferson,&nbsp;Frederick I. Archer,&nbsp;Kelly M. Robertson","doi":"10.1111/mms.13133","DOIUrl":"10.1111/mms.13133","url":null,"abstract":"<p>Neritic, long-beaked common dolphins have been described as species distinct from the more oceanic and globally distributed short-beaked species, <i>Delphinus delphis</i>, although recent molecular studies have challenged this view. In the eastern North Pacific (ENP), the taxonomic status of the long-beaked (<i>bairdii</i>) form has been controversial since its original description in 1873, and has vacillated between species, subspecies, and geographic forms several times. It is currently provisionally viewed as a subspecies of <i>Delphinus delphis</i>, <i>D. d. bairdii</i>. To clarify this situation, we reviewed the literature and conducted additional analyses using both newly obtained genetic and cranial morphometric data sets. The results indicate that there are diagnostic differences in skull morphology and coloration between the eastern Pacific long-and short-beaked forms, and near-perfect diagnosability in mitochondrial DNA. These differences, along with indications of ecological distinctions, including important differences in life history parameters and reproductive timing, indicate that these forms are well on their way down separate evolutionary pathways. As such, we consider them to be distinct species in the eastern Pacific. The long-beaked species is referable to <i>Delphinus bairdii</i> Dall, 1873, and is redescribed as such herein.</p>","PeriodicalId":18725,"journal":{"name":"Marine Mammal Science","volume":"40 4","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/mms.13133","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140835344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A preliminary description of Atlantic white-sided dolphin (Lagenorhynchus acutus) vocalizations","authors":"Susannah Calderan,&nbsp;Oliver Boisseau,&nbsp;Claire Lacey,&nbsp;Russell Leaper,&nbsp;Nienke van Geel,&nbsp;Denise Risch","doi":"10.1111/mms.13135","DOIUrl":"10.1111/mms.13135","url":null,"abstract":"&lt;p&gt;Atlantic white-sided dolphins (&lt;i&gt;Lagenorhynchus acutus&lt;/i&gt;) are endemic to the North Atlantic Ocean, predominantly inhabiting the cold-temperate and subpolar waters around the continental shelf and slope. Their geographic range extends from the western North Atlantic across to the eastern North Atlantic, and includes the Norwegian and North Seas, but their distribution patterns are not well-understood (Cipriano, &lt;span&gt;2018&lt;/span&gt;; Vollmer et al., &lt;span&gt;2019&lt;/span&gt;). There is a relatively high occurrence of mass strandings by this species, and it is also impacted by anthropogenic threats such as bycatch in a variety of gear types, including trawls and gill nets (Addink et al., &lt;span&gt;1997&lt;/span&gt;; Bogomolni et al., &lt;span&gt;2010&lt;/span&gt;; Couperus, &lt;span&gt;1997&lt;/span&gt;; Kinze et al., &lt;span&gt;1997&lt;/span&gt;; Palka et al., &lt;span&gt;1997&lt;/span&gt;). Additionally, Atlantic white-sided dolphins are hunted, primarily in the Faroe Islands, where, for example, 1,428 individuals were killed in a single drive hunt in 2021 (https://nammco.no/topics/atlantic-white-sided-dolphin/; Calderan, &lt;span&gt;2021&lt;/span&gt;; Fielding, &lt;span&gt;2021&lt;/span&gt;). They are thus one of the most heavily exploited cetacean species in the North Atlantic, yet also one of the most poorly-understood. Passive acoustic monitoring (PAM) has the potential to contribute to knowledge on their occurrence, but there is only limited information on white-sided dolphin vocalizations (Cones et al., &lt;span&gt;2023&lt;/span&gt;; Hamran, &lt;span&gt;2014&lt;/span&gt;). It is therefore not currently possible to analyze the many data sets collected from acoustic moorings and towed array surveys to improve knowledge of the species' temporal and spatial distribution.&lt;/p&gt;&lt;p&gt;Most dolphin species produce tonal and pulsed vocalizations, including whistles, echolocation clicks, and burst pulses. Echolocation clicks are typically associated with foraging and navigation, and whistles and burst pulses with social communication (Au, &lt;span&gt;1993&lt;/span&gt;; Herzing, &lt;span&gt;1996&lt;/span&gt;). Whistles are frequency-modulated tonal sounds (Herman &amp; Tavolga, &lt;span&gt;1980&lt;/span&gt;). Echolocation clicks are short-duration, directional clicks (Au, &lt;span&gt;1993&lt;/span&gt;); burst pulses also comprise clicks, where broadband pulsed signals with significant ultrasonic frequency components are produced with a very high repetition rate and short interclick interval (Au &amp; Hastings, &lt;span&gt;2008&lt;/span&gt;; Blomquist &amp; Amundin, &lt;span&gt;2004&lt;/span&gt;). Clicks associated with burst pulses are reported to be shorter in duration, more directional, and have lower peak and center frequencies than those associated with echolocation click trains (Au &amp; Hastings, &lt;span&gt;2008&lt;/span&gt;; Rankin et al., &lt;span&gt;2007&lt;/span&gt;). All three vocalization types can include specific information useful for classifying to species level (Rankin et al., &lt;span&gt;2016&lt;/span&gt;). The limited data on the clicks produced by &lt;i&gt;Lagenorhynchus&lt;/i&gt; species indicate interspecies variability in their characteristics. For example, d","PeriodicalId":18725,"journal":{"name":"Marine Mammal Science","volume":"40 4","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/mms.13135","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140835325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Examining Bergmann's rule in a cosmopolitan marine mammal, the bottlenose dolphin (Tursiops spp.)","authors":"Arina B. Favilla,&nbsp;Stephanie K. Adamczak,&nbsp;Erin M. Fougères,&nbsp;Andrew Brownlow,&nbsp;Nicholas J. Davison,&nbsp;Janet Mann,&nbsp;William A. McLellan,&nbsp;D. Ann Pabst,&nbsp;Mariel T. I. ten Doeschate,&nbsp;Michael S. Tift,&nbsp;Randall S. Wells,&nbsp;Daniel P. Costa","doi":"10.1111/mms.13130","DOIUrl":"10.1111/mms.13130","url":null,"abstract":"&lt;p&gt;Body size is a life-history trait with significant ecological and physiological implications. As a group, marine mammals are the largest mammals on earth. The smallest marine mammal (by mass) is the marine otter (&lt;i&gt;Lontra felina&lt;/i&gt;), weighing 3–5 kg (Jefferson et al., &lt;span&gt;2015&lt;/span&gt;), which is over 10 times as much as the smallest terrestrial mammal, the Etruscan shrew (&lt;i&gt;Suncus etruscus&lt;/i&gt;), weighing 1.8 g (Jürgens, &lt;span&gt;2002&lt;/span&gt;). Similarly, for the opposite end of the size spectrum, the blue whale (&lt;i&gt;Balaenoptera musculus&lt;/i&gt;)—the largest animal to have ever lived—is approximately 150,000 kg (Sears &amp; Calambokidis, &lt;span&gt;2002&lt;/span&gt;) compared to the 5,000 kg African elephant (&lt;i&gt;Loxodonta africana&lt;/i&gt;; Laurson &amp; Bekoff, &lt;span&gt;1978&lt;/span&gt;). The large body size attained by marine mammals represents an evolutionary trend to balance energy costs associated with thermoregulation and foraging (Gearty et al., &lt;span&gt;2018&lt;/span&gt;; Goldbogen, &lt;span&gt;2018&lt;/span&gt;; Williams, &lt;span&gt;1999&lt;/span&gt;) and selects for larger neonates (Christiansen et al., &lt;span&gt;2014&lt;/span&gt;, &lt;span&gt;2018&lt;/span&gt;). The lower limit of body size in marine mammals is thought to be constrained by the thermal demand of seawater, which conducts heat 25 times faster than air at the same temperature.&lt;/p&gt;&lt;p&gt;Body size largely determines surface area to volume (SA:V) ratios. Smaller animals have a larger surface area for a given volume, resulting in thermoregulatory consequences. Surface area (SA) represents the area over which heat can be lost to the environment. Volume (V) represents internal heat generation as metabolism scales with mass, which scales isometrically with volume. Large body size is advantageous for conserving heat since larger animals have lower SA:V ratios due to the scaling relationships between length, SA (length&lt;sup&gt;2&lt;/sup&gt;), and V (length&lt;sup&gt;3&lt;/sup&gt;) (reviewed by Ashton et al., &lt;span&gt;2000&lt;/span&gt;). This scaling relationship yields a more rapid increase in V than in SA with body length (cubed vs. squared), resulting in greater heat generation and retention relative to heat dissipation. In marine mammals, species inhabiting colder climates minimize their SA:V ratio by changing body shape and/or increasing body size, which reduces heat loss compared to those in warmer climates (Adamczak et al., &lt;span&gt;2020&lt;/span&gt;; Worthy &amp; Edwards, &lt;span&gt;1990&lt;/span&gt;).&lt;/p&gt;&lt;p&gt;This trend has been described for both terrestrial (James, &lt;span&gt;1970&lt;/span&gt;) and marine mammals (Ashton et al., &lt;span&gt;2000&lt;/span&gt;; Torres-Romero et al., &lt;span&gt;2016&lt;/span&gt;) under Bergmann's rule. Bergmann's rule was first proposed in 1847 (Bergmann, &lt;span&gt;1847&lt;/span&gt;) to explain the congeneric pattern of larger animals (specifically endotherms) in higher latitudes with colder climates. Since its conception, Bergmann's rule has also been investigated within species and across species as well as in endotherms and ectotherms, demonstrating its open criteria (Meiri, &lt;span&gt;2011&lt;/span&gt;). In marine species, B","PeriodicalId":18725,"journal":{"name":"Marine Mammal Science","volume":"40 4","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/mms.13130","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140835758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Estimated reproductive parameters for a vulnerable Australian humpback dolphin population","authors":"Elizabeth R. Hawkins,&nbsp;Merryn Dunleavy","doi":"10.1111/mms.13131","DOIUrl":"10.1111/mms.13131","url":null,"abstract":"<p>Understanding reproductive output and success is integral to the conservation and management of threatened species and populations. Little is known about the reproductive parameters of Australian humpback dolphins (<i>Sousa sahulensis</i>), a species subject to cumulative pressures from anthropogenic threats due to their coastal distribution and strong site fidelity. This study assesses several reproductive parameters, including crude birth, recruitment, fecundity, and calf survival rates, in addition to interbirth intervals of Australian humpback dolphins inhabiting the near-urban embayment of Moreton Bay, Queensland. Between 2014 and 2020, 106 adult females were photographically identified during 222 boat surveys. Of these, 75.5% (<i>n</i> = 80) were observed with calves. Birth seasonality was apparent and coincided with austral autumn and winter months. Interbirth intervals ranged between 1 and &gt;6 years, with an average of 3.1 (<i>SD</i> = 1.1) years if offspring survived. Findings indicate declining fecundity rates (<i>p</i> &lt; .05, <i>M</i> = 0.12, <i>SD =</i> 0.02), relatively low recruitment rates (<i>M</i> = 0.04, <i>SD</i> = 0.01) and calf survival rates to 1 year of age (<i>M</i> = 0.63, <i>SD =</i> 0.15). This study provides a useful baseline that can inform viability assessments and conservation measures, for both this population and others throughout the species range.</p>","PeriodicalId":18725,"journal":{"name":"Marine Mammal Science","volume":"40 4","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140670299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}