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Kamel Larbi Doukara 《水产资源保护:海洋与淡水生态系统》2021,31(Z1):8-14
- Marine mammals stranding data provide valuable information on causes of mortality for cetacean populations. The aim of this study was to investigate the characteristics of the stranding events of common dolphins along the Algerian west coast, and estimate the proportion of human vs. non-human induced mortality of the population.
- Between 2008 and 2012, out of the 52 cetacean stranding records along the Algerian west coast, common dolphins (Delphinus delphis) were recorded in 14 cases. All recorded strandings were of individual cases with no mass strandings registered during the reported period.
- To examine the proportion of human and non-human induced mortality affecting this population, necropsies were conducted. In 10 cases, an interaction with some type of fishing gear had occurred; in three, there was no link with human activity; and in one case, it was not possible to determine the cause of death due to the condition of the carcass (severely decomposed).
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Leena Riekkola Virginia Andrews‐Goff Ari Friedlaender Alexandre N. Zerbini Rochelle Constantine 《水产资源保护:海洋与淡水生态系统》2020,30(5):937-948
- Long‐distance migration is a demanding physical activity, and how well animals manage the associated costs will have important implications for their fitness.
- The Oceania humpback whale (Megaptera novaeangliae) population is recovering from past exploitation markedly slower than the neighbouring east Australian whales. The reasons for this are unknown, although higher energetic costs of longer migratory distances could be a possible explanation. Due to their fully aquatic lives, studying the energy expenditure of these large animals requires methods that do not rely on capturing the animal, such as bioenergetic models.
- A state‐space model was fitted to satellite data to infer behavioural states for southern migrating whales. Travel speeds and behavioural states were used in a bioenergetic model to estimate the energetic cost of the migration phase. Relative differences in average duration, distance, and energetic costs were compared between migratory routes and distances.
- Total energy used during migration was a trade‐off between cost of transport (determined by travel speed) and daily maintenance (determined by daily basal metabolic costs). Oceania whales migrating to the Amundsen and Bellingshausen Seas travelled fastest and furthest, 15 and 21% further than whales migrating to the d'Urville Sea (east Australian whales) and Ross Sea, respectively. Therefore, they had the highest cost of transport, 25 and 85% higher than for d'Urville Sea and Ross Sea whales, respectively. However, energy saved in terms of daily maintenance by using fewer days to complete a longer migration resulted in only a 6–7% increase in total energetic cost.
- The results highlight that travelling further does not necessarily translate into an increase in total energy expenditure for migratory whales, since they can compensate for longer distance by travelling faster. Further research on the energetics of different whale populations could provide insight into the productivity of Southern Ocean feeding regions and help understand the environmental and anthropogenic effects on the whales' energy budgets.
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Alicia Bertoloto Tagliolatto Daphne Wrobel Goldberg Matthew H. Godfrey Cassiano Monteiro‐Neto 《水产资源保护:海洋与淡水生态系统》2020,30(2):331-350
- Data on stranded sea turtles were examined between 2010 and 2016 along the northern region of Rio de Janeiro state and between 2016 and 2017 in the southern region, looking for spatio‐temporal patterns and determining which factors contributed to their mortality.
- A total of 12,162 strandings of all five species that occur in Brazil were recorded, with Chelonia mydas being the most common (89.9%). Sea turtles use the Rio de Janeiro coast as a feeding and/or migration area. The intense upwelling (October to April) may be an important factor for the sea turtles feeding in this region, mainly for Eretmochelys imbricata and Dermochelys coriacea, which had a higher number of strandings during this period.
- Areas further north of the study area include an important nesting site for Caretta caretta in Brazil, which explains the higher concentration of strandings of subadults/adults of this species in this region and during its nesting season.
- Many anthropogenic threats to sea turtles were documented, mainly incidental capture in fisheries and marine debris, indicating possible hotspots for these threats in the regions of Sepetiba and Guanabara Bays, Cabo Frio, and São Francisco de Itabapoana.
- Among the natural causes of strandings, the primary factors were chronic illness, endoparasites, and fibropapillomatosis. However, pollution may also be an indirect threat, which negatively affects these animals through reduced health and immunosuppression, leaving them more susceptible to opportunistic diseases.
- These data are valuable for directing and implementing specific and local mitigation measures along the Rio de Janeiro state coast, such as avoiding bycatch hotspots through fleet communication programmes and/or area and seasonal closures, enforceable legislation, effective penalties and proper waste management.
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《Fisheries Research》2007,88(2-3):219-228
Information on the migration patterns of sperm whales (Physeter macrocephalus) in the North Atlantic is preserved in historical strandings records, particularly for the North Sea, where sperm whale strandings have been documented since the 16th century, reflecting general public interest in large whales ashore. Most strandings in this area occur during or following the southward migration from the feeding grounds, when some animals enter the North Sea (in which they are thought to have difficulty navigating) instead of following their usual route through deep water to the west of the British Isles. There was much speculation about the causes of the high incidence of strandings on North Sea coasts in the 1990s, among which a recently published analysis of long-term trends in strandings indicated an effect of sunspot cycle length. We show that long-term interannual variation in the incidence of sperm whale strandings on North Sea coasts is related to positive temperature anomalies: the incidence of strandings was higher in warmer periods. The effect of temperature anomalies explains between 8 and 9% of variation in the strandings series. Inclusion of sunspot cycle length as an additional predictor did not significantly improve this model. It is suggested that this link with positive temperature anomalies may reflect changes in the distribution of the sperm whales’ main squid prey. 相似文献
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Joanna Day David Power Rosemary Gales John Bannister Maxine P. Piggott Kerstin Bilgmann Robert Harcourt Luciano B. Beheregaray Luciana M. Möller 《水产资源保护:海洋与淡水生态系统》2021,31(6):1452-1465
- Understanding the factors driving population structure in marine mammals is needed to evaluate the impacts of previous exploitation, current anthropogenic threats, conservation status, and success of population recovery efforts.
- Sperm whales are characterized by a worldwide distribution, low genetic diversity, complex patterns of social and genetic structure that differ significantly within and between ocean basins, and a long history of being commercially whaled. In Australia, sperm whales from the (International Whaling Commission assigned) southern hemisphere ‘Division 5’ stock were very heavily exploited by whaling.
- The present study assessed the potential effects of whaling on the genetic diversity of sperm whales in Australia and the population genetic structure of these whales within a global context. A combination of historical and contemporary sperm whale samples (n = 157) were analysed across six regions, from south-eastern Australia (‘Division 6’ stock in the Pacific Ocean) to south-western Australia (‘Division 5’ stock in the Indian Ocean).
- Sperm whales sampled from the ‘Division 5’ and ‘Division 6’ stocks belong to the same population based on nuclear and mitochondrial DNA (mtDNA) analyses. Four novel sperm whale mtDNA haplotypes were identified in animals from Australian waters. Levels of genetic diversity were low in Australian sperm whales but were similar to those previously reported for populations in the Indian and Pacific Oceans.
- Given the genetic distinctiveness of sperm whales in Australian waters from other regions in the Pacific and Indian Oceans, and the lack of recovery in population numbers, further scientific studies are needed to increase our understanding of population dynamics and the effectiveness of threat management strategies in this species.
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Paolo Casale Marco Affronte Gianni Insacco Daniela Freggi Carola Vallini Paola Pino d'Astore Roberto Basso Giuseppe Paolillo Graziana Abbate Roberto Argano 《水产资源保护:海洋与淡水生态系统》2010,20(6):611-620
- 1. Spatio‐temporal distribution and anthropogenic mortality factors were investigated in loggerhead turtles (Caretta caretta) found stranded or floating in the waters around Italy. A total of 5938 records for the period 1980–2008 were analysed concerning loggerhead turtles measuring from 3.8 to 97 cm curved carapace length (mean: 48.3 cm).
- 2. Results highlighted the following conservation issues: (i) in the study area, anthropogenic mortality is higher than natural mortality; (ii) interaction with fisheries is by far the most important anthropogenic mortality factor; (iii) longlines are an important mortality factor in the southern areas; (iv) trawlers are the cause of high numbers of dead strandings in the north Adriatic; (v) entanglement in ghost‐gear or in other anthropogenic debris affects high numbers of turtles; and (vi) boat strikes are an important source of mortality in most areas but mostly in the warm seasons.
- 3. Results also indicate that: (vii) the north Adriatic is the area with the highest turtle density; and (viii) the south Adriatic and to a lesser extent the surrounding areas of the north Adriatic and the Ionian, are important developmental areas for loggerhead turtles in the first years of life.
- 4. Italy is in the centre of the Mediterranean Sea and borders major foraging areas for the loggerhead turtles in the region, and these results confirm previous concerns about the level of anthropogenic mortality in Italian waters. Copyright © 2010 John Wiley & Sons, Ltd.
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Francisca C. Aguiar M. Teresa Ferreira António Albuquerque Ilídio Moreira 《水产资源保护:海洋与淡水生态系统》2007,17(4):335-347
- 1. A comparison was made between a variety of alien and endemic plant species from 272 aquatic and riparian habitats in Portuguese Mediterranean‐type streams in reference condition — i.e. near‐natural river corridors — and non‐reference condition. The objective was to detect differences in relative proportion and cover between these species groups. The differences in endemic and alien flora from siliceous and calcareous river types were also analysed. Environmental and human disturbance factors were related with the richness and cover of both species groups.
- 2. A total of 568 species were found, of which 44 were alien and 28 were endemic. Alien species were present at 91% of the surveyed locations, and were consistently more widespread at non‐reference sites than at reference ones for both river types, with calcareous sites having a higher invasibility. Endemic species occurred at 45% of the sampling sites and displayed a significantly lower richness and cover than their alien counterparts.
- 3. Alien richness and cover were positively related to direct human disturbance within the river systems, and with floodplain uses such as urban occupation, intensive agriculture, and nutrient inputs. Endemic species also respond to anthropogenic variables, rather than to climatic and geographical ones, with richness and cover increasing as human impacts on fluvial systems and related floodplains decrease.
- 4. Comprehensive control of alien invasive species and the protection of endemic plant populations will require attempts at monitoring ecological river integrity, and the achievement of ‘good ecological status’ — one of the goals of the European Union's Water Framework Directive. Portuguese riparian areas must be managed in such a way as to protect the relatively few preserved riparian habitats by lowering the direct and indirect pressures in fluvial corridors and thus preventing future alien plant invasions.
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- 1. In summer 2001, 252 members of the public in south‐west Scotland were interviewed to determine their awareness of, and opinions on, cetacean conservation issues in Scotland. Interviews were conducted in both rural island and coastal communities and a major city. Interviewees were also presented with a list of threats to cetaceans and were asked to gauge how serious they considered these threats to be for cetaceans in the waters of western Scotland.
- 2. Oil spills (43.7%), reduction in available prey (41.8%), marine litter (32%) and sewage bacteria (31.1%) were ranked by most members of the public as being ‘serious threats’.
- 3. Least concern was expressed in relation to whale watching: only 0.8% of respondents considered whale watching to be a serious threat and 51.2% thought that it posed no threat at all.
- 4. In relation to the other threats considered, there was a moderate level of concern about fishery by‐catches and pollution from aquaculture and land‐based sources.
- 5. Levels of concern about disturbance caused by quarrying, dredging and military activities were generally low, despite these factors having been raised by some as being conservation issues in west Scotland.
- 6. The majority of participants (69.4%) were aware of whaling operations currently being conducted by Japan and Norway. Almost all participants were against these countries hunting whales (96.4%).
- 7. Interviewees were also asked for their opinion regarding the level of protection currently afforded to cetaceans by the Scottish Government. Virtually no interviewee considered cetaceans to be overprotected in Scotland (0.4%). A substantial proportion were of the opinion that they are not sufficiently protected (45.6%). Of these, virtually all (94.8%) thought that legislation specifically for the protection of cetaceans in Scotland should be introduced.
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The future of marine citizenship is now: Cetacean conservation in the eyes of young Spanish citizens
- The number of young conservationist movements is increasing worldwide, as new generations become more aware of the environmental problems that are having an impact on the planet. Consequently, young people appear to play a fundamental role in developing successful conservation strategies.
- This research examines young citizens’ knowledge, attitudes and engagement in cetacean conservation in coastal and non-coastal regions of Spain, and assesses the influence of whaling tradition.
- A total of 902 anonymous surveys were conducted with students between 14 and 16 years old at 10 high schools located in nine different study areas, six located along the Cantabrian coast (Southern Bay of Biscay) and three located in inland regions of Spain.
- In general, results showed low levels of knowledge about cetaceans and whaling among young people, but high concern about cetacean conservation. As it was expected, knowledge about the history of whaling was higher in participants from areas with than without a whaling tradition. However, no statistically significant differences were found regarding attitudes towards cetaceans between these two groups.
- Significant differences were detected between genders with respect to cetacean conservation and engagement. Females showed more positive attitudes towards cetaceans when compared with their male counterparts.
- A correlation between knowledge and positive attitudes regarding whales and dolphins was found in areas located along the Cantabrian coast, and a correlation between positive attitudes and engagement in cetacean conservation was observed in all study areas.
- Although the majority of participants showed strong support for the protection of whales and dolphins, less than two-thirds stated that they were willing to engage in cetacean conservation.
- The results of this study may contribute to the implementation of improved marine education programmes. These programmes should not only raise awareness of the marine environment, but also promote pro-environmental behaviour and engagement in the protection of the ocean.
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- 1. Cetacean observations were made by fisheries observers on trawlers targeting Greenland halibut (Reinhardtius hippoglossoides) in the area around the Flemish Cap, northwest Atlantic.
- 2. Data from four observers amounted to a total of 291 observer days at sea aboard fishing vessels. This effort was mainly concentrated in the periods July to September 1996 and February to April 1997.
- 3. Sperm whales (Physeter macrocephalus) were the most frequently sighted cetacean, with 82 encounters on 64 different days. Pilot whales were encountered on nine occasions.
- 4. Sighting rates of sperm whales during net hauling were significantly (approximately 30 times) greater than during shooting or steaming. Sperm whales were observed in aggregations of up to six animals close to the vessel and net during hauling. It is suggested that the sperm whales were attracted by the potential food source within the net, and possibly were feeding on fish escaping from the net. This represents rarely reported behaviour for this species.