Long-term study of at-sea distribution of seabirds and marine mammals in the Scotia Sea,Antarctica

The Scotia Sea is one of the most biologically rich regions of Antarctica, and it hosts a large community of upper trophic-level predators. Long-term at-sea monitoring provides valuable information on ...     

中西太平洋延绳钓渔业鲸类兼捕的空间变化及其环境影响

鲸类物种和延绳钓渔具之间的相互作用是一种全球性现象,该相互作用威胁到鲸类物种的保护和延绳钓渔业的经济可行性。尽管认识到鲸类兼捕问题,但很少对其影响进行全面评估。根据中西部太平洋渔业委员会(WCPFC)科学机构提供的2013—2019年期间的观察员数据,利用广义可加模型(GAM)分析金枪鱼延绳钓渔业中兼捕的鲸类与时空和环境因子的关系。结果表明:在中西太平洋海域,共兼捕260头鲸类,隶属于2目5科19种,主要的兼捕对象是伪虎鲸(Pseudorca crassidens)、瓶鼻海豚(Tursiops truncatus)、里氏海豚(Grampus griseus)、短鳍领航鲸(Globicephala macrorhynchus)、糙齿海豚(Steno bredanensis)等。GAM模型对BPUE的总偏差解释率为71.7%,经度的贡献率最大为34.3%,各预测变量的相对重要性分别为经度>海表温度>叶绿素a浓度>纬度>单位捕捞努力量渔获量(CPUE)。鲸类兼捕主要由空间和环境因子所决定,其中海表温度主要影响鲸类的相对丰度,叶绿素a浓度影响鲸类的分布。未来,渔业管理者...     

Abundance estimates of an isolated population of common bottlenose dolphins Tursiops truncatus in Walvis Bay,Namibia, 2008–2012

The coastal population of common bottlenose dolphins Tursiops truncatus found in Namibia is regionally isolated and unique. This population faces several potential anthropogenic threats, especially in Walvis Bay, including boat-based tourism, a commercial harbour undergoing expansion, and aquaculture for oysters and mussels. Between 2008 and 2012, 238 boat-based surveys were conducted, resulting in 170 encounters with bottlenose dolphins. Overall, group sizes varied from 1 to 45 individuals (mean 10.7). Encounter rates, group sizes and total numbers of animals identified were higher in winter than in summer field seasons. The number, and survival and immigration parameters, of bottlenose dolphins using Walvis Bay was investigated using robust design and Huggins closed-population mark-recapture models. The highest numbers estimated were in the first and last years of the study, with estimates of 74–82 in 2008 and 76–77 in 2012 (numbers identified and upper 95% confidence limits). The only previously available data, from an incomplete study in the early 1990s, suggested that the population was between 100 and 150 individuals at the time. Although no linear trend in population size was obvious during the current study, the clear evidence of isolation, small population size, low annual birth rate, and potential long-term decrease in numbers since the early 1990s is concerning. Further work to collect data on demographic parameters is urgently recommended with a view to obtaining increased protection for this species.     

Structure of a toothed cetacean community around a tropical island (Mayotte,Mozambique Channel)

We describe the structure of a toothed cetacean community around the island of Mayotte (South-West Indian Ocean, 45°10′ E, 12°50′ S), using data collected from small boat-based surveys conducted between July 2004 and June 2006. In all, 16 odontocete species were recorded. Diversity (Shannon-Weaver index) was particularly high along the outer slope of the barrier reef. Patterns of spatial distribution underscore the existence of three main cetacean habitat types: the inner lagoon (Indo-Pacific bottlenosed dolphin Tursiops aduncus and humpback dolphin Sousa chinensis), the outer-reef slope (spinner dolphin Stenella longirostris, pantropical spotted dolphin S. attenuate and melon-headed whale Peponocephala electra) and oceanic waters deeper than 500 m (e.g. Blainville's beaked whale Mesoplodon densirostris). Group characteristics were highly variable among species, with oceanic small delphinids characterised by larger group sizes than strictly coastal and non-delphinid oceanic species. The outer slope of the barrier reef appears to be of primary importance in terms of density and diversity of odontocetes around Mayotte. Results support the hypothesis that a number of cetacean species, particularly several delphinid species, are dependent on coral reef complexes.     

珠江口3种鲸豚的MHC-I基因多态性研究

旨在了解珠江口栖息的中华白海豚(Sousa chinensis)、宽脊江豚(Neophocaena phocaenoides)和点斑原海豚(Stenella attenuate)免疫相关基因MHC-I(Major Histocompatibility Complex)的多态性及其表达情况,以期为这3种鲸豚的保育工作提供基础资料。通过克隆测序的方法,首次证实MHC-I基因在这3种鲸豚体内表达。选择压力分析,表明MHC-I基因在这3种鲸豚中均受到强烈的正选择作用,提示其具有重要的免疫功能。3种鲸豚的MHC-I基因在系统发育树上相互混杂在一起,表明MHC-I基因存在跨物种多态性。结合选择压力分析和跨物种多态性,发现MHC-I基因受到平衡选择作用。珠江口3种鲸豚MHC-I基因多态性可能由平衡选择维持。     

Stomach contents of cetaceans incidentally caught along Mangalore and Chennai coasts of India

The stomachs of 32 individuals of seven cetacean species incidentally caught in gill net and purseseine fisheries along Mangalore and Chennai coasts (India) between 2004 and 2006 were examined. The whole stomach (fore-gut, mid-gut and hind-gut) was examined in all cases. Prey remains (666 prey items comprising six species of teleosts, one crustacean and one squid species) were found in the stomachs of eight individuals (the remaining 24 stomachs were found to be empty). All cetaceans were found to feed mostly on teleosts with wide range of trophic levels. Based on an index that included frequency of occurrence, percentage by number and by weight, the oil sardine Sardinella longiceps was the main prey in the sample. Cetaceans appear to favour both pelagic as well as demersal prey, possibly indicating surface and benthic feeding habits.     

Trends in tagging of marine mammals: a review of marine mammal biologging studies

The number of scientific papers resulting from biologging instruments deployed on marine mammals is increasing as improved technologies result in smaller devices and improved sensor-, storage- and transmission capabilities. I undertook a comprehensive review of papers resulting from biologging deployments on free-ranging marine mammals between 1965 and 2013 (n = 620) to summarise where (e.g. on which species, as well as in which geographic areas) deployment efforts were focused, the impacts of the resulting papers, and where there are shortcomings in the literature. Species-, sex- and age-class biases were evident in terms of animals instrumented. Also, large proportions of the papers resulted from deployments on a small number of species (particularly among the pinnipeds) and were more often on adult females than other demographic classes. The mean impact of papers (as assessed using journal impact factors and numbers of citations) was consistent over time, and was influenced by the number of species studied, sample sizes and instrument capabilities. I found a paucity of papers addressing device influences on animals, as well as studies with explicit conservation and/or management implications. This review aims to increase awareness of marine mammal biologging data already collected, stimulate appropriate further studies, and encourage the reuse of existing data.     

Butyltin Contamination in Marine Mammals – A Review

In order to understand organotin accumulation in marine mammals, the present study determined the concentrations of butyltins (BTs) in various tissues and organs and described their distribution patterns relative to sex, age and geographical factors. Both cetaceans and pinnipeds showed higher BTs concentrations in the liver amongst various tissues and organs. In addition, noticeably high concentrations were found in the hair of pinnipeds, indicating possible excretion of BTs through shedding. BTs composition in mammals and their prey organisms suggested that pinnipeds have a stronger capacity to degrade BTs as compared to cetaceans. No age trends of BTs concentrations were observed in pinnipeds, while cetaceans showed increasing levels in immature growth stages. Comparing butyltin concentrations in various marine mammals, cetaceans retained higher butyltin concentrations than pinnipeds. These specific accumulation patterns found in marine mammals are probably attributable to the lower breakdown capacity of BTs in cetaceans and the significant excretion of BTs through shedding in pinnipeds. Unlike organochlorines, comparable residue levels of butyltins were found in male and female marine mammals. Such a trend suggests that butyltins are less transferable through gestation and lactation from mother to fetus/pup. On a global perspective, residue levels were found to be prominent in the coastal waters of developed nations. The present contamination by BTs may pose a considerable toxic threat to some coastal species of cetaceans. A relatively high percentage of BTs in total tin was found in the liver of cetaceans. This finding suggests that the hepatic tin in cetaceans exists predominantly in organic forms such as butyltin compounds, implying further that tin residues in marine mammals mostly reflects input from anthropogenic sources.