共查询到10条相似文献,搜索用时 109 毫秒
1.
Caitlin K. Frankish Andrea Manica Joan Navarro Richard A. Phillips 《水产资源保护:海洋与淡水生态系统》2021,31(7):1715-1729
- Many seabirds dive to forage, and the ability to use this hunting technique varies according to such factors as morphology, physiology, prey availability, and ambient light levels. Proficient divers are more able to seize sinking baits deployed by longline fishing vessels and may return them to the surface, increasing exposure of other species. Hence, diving ability has major implications for mitigating incidental mortality (bycatch) in fisheries.
- Here, the diving behaviour and activity patterns of the most bycaught seabird species worldwide, the white-chinned petrel (Procellaria aequinoctialis), tracked from Bird Island (South Georgia), are analysed. Three data sources (dives, spatial movements, and immersion events) are combined to examine diverse aspects of at-sea foraging behaviour, and their implications for alternative approaches to bycatch mitigation are considered.
- The tracked white-chinned petrels (n = 14) mostly performed shallow dives (<3 m deep) of very short duration (<5 s), predominantly during darkness, but only 7 and 10% of landings in daylight and darkness, respectively, involved diving, suggesting that surface-seizing is the preferred foraging technique. Nonetheless, individuals were able to dive to considerable depth (max = 14.5 m) and at speed (max = 2.0 m·s−1), underlining the importance of using heavy line-weighting to maximize hook sink rates, and bird-scaring lines (Tori lines) that extend for long distances behind vessels to protect hooks until beyond diving depths.
2.
Jhann Garar Þorbjrnsson Jnína Herdís
lafsdttir Bjarni Kristfer Kristjnsson Catherine Chambers Georgette Leah Burns 《水产资源保护:海洋与淡水生态系统》2020,30(5):1012-1022
- Ecological damage by scuba divers has been extensively studied in marine ecosystems, particularly coral reefs, whereas the impacts on freshwater environments such as groundwater springs is unknown. In the Silfra groundwater fissure in Iceland, a vast increase in diver entries has occurred during the last decade, prompting concerns over potential ecosystem impacts and visitor carrying capacity.
- Here, a mixed‐method approach was used to assess the impacts of scuba diving in Silfra. (a) Divers were recorded under water to observe the mechanisms of diver‐related disturbances, (b) benthic material was collected along transects in Silfra and the undisturbed fissure Flosagjá to compare biofilm biomass and zoobenthic communities between and within fissures, and (c) the perceptions and experiences of stakeholders surrounding the dive tourism in Silfra were explored.
- Underwater observations showed that 91.4% of the divers caused at least a single disturbance, resulting in biofilm detachments and/or sediment stirring. Diver fins caused the most frequent disturbances, predominantly through fin‐generated currents but also by directly contacting the substrate. Benthic biofilm biomass was lower in Silfra than Flosagjá and exhibited a negative correlation with dive‐use. Some disturbance‐tolerant zoobenthic groups exhibited moderate to strong correlations with dive‐use.
- All stakeholders had negative perceptions towards increasing diver entries, but although entry limitation could improve tourism quality, disturbance might only minimally be reduced as springs like Silfra may be particularly sensitive.
- Springs are characteristically stable and uniform environments that can be vulnerable to disturbance. Their use for scuba diving should be carefully managed through a holistic approach and an active collaboration between all stakeholders.
3.
Diving for science ‐ science for diving: volunteer scuba divers support science and conservation in the Mediterranean Sea 下载免费PDF全文
- Recreational diving engages 20 million people worldwide. Most of the literature refers to tropical destinations but at least 1 million dives per year take place in Mediterranean marine protected areas (MPAs).
- Divers may negatively affect underwater habitats. However, if effectively engaged, they can contribute to science, territorial management and more sustainable local economies.
- During 2006–2014, volunteers trained by the not‐for‐profit organization Reef Check Italia (RCI) completed 24 714 observations and 2417 dives in six Mediterranean countries, contributing to a dataset that supports scientific papers about climate change, rare and non‐indigenous species (NIS), and informs MPA management decision‐making.
- The wide range of opportunities offered by this dataset is illustrated with two examples relevant to marine conservation in the context of MPA management. They concern: (i) the spread of the NIS Caulerpa cylindracea along the Ligurian coasts, with a focus on Portofino MPA, and (ii) the distribution and abundance of protected species in the Portofino MPA.
- A diver‐focused survey showed that RCI volunteers are highly committed, and that participation in RCI activities has led to a better understanding of, and a sense of stewardship towards, favoured dive sites and the marine world. Knowing who volunteers are, and why they volunteer in their favourite sector, is crucial to designing citizen‐science based projects able to achieve their multiple goals.
4.
Sebastián Jiménez Andrés Domingo Martin Abreu Alejandro Brazeiro 《水产资源保护:海洋与淡水生态系统》2012,22(4):436-445
- Species of petrels and shearwaters with high diving ability could facilitate the catch of albatrosses in pelagic longline fisheries, because they retrieve bait to the surface from depths that albatrosses cannot reach. Once on the surface, large seabirds such as albatrosses can easily displace smaller species thus gaining access to baited hooks which increases their likelihood of getting caught.
- This paper evaluates the extent to which diving species (i.e. Procellaria aequinoctialis, Procellaria conspicillata and Puffinus gravis) increase the susceptibility of albatross to bycatch in pelagic longline fisheries. In 48 sets, attacks on baits were quantified. When more than one bird (of the same or different species) tried to attack the same bait this was defined as a multiple attack.
- There were 384 attacks on baits, of which 260 were made by a single individual and 124 by more than one. Multiple attacks were the largest source of bycatch of albatrosses (22 of 27 albatrosses whose attacks were observed).
- Of the baits attacked by albatrosses (n = 244), 17% were indirectly facilitated by diving medium‐sized petrels. Considering only the multiple attacks in which albatrosses participated (n = 114), 36% were initiated by these medium‐sized petrels. Eleven (41%) of the albatrosses captured, and whose attacks were observed, resulted from a diving medium‐sized seabird species first having contacted the terminal tackle.
- This paper shows that medium‐sized petrels, with a strong ability to dive, increase considerably the access to bait, and indirectly, the incidental bycatch of albatrosses. Observations made in the absence of mitigation measures also provide useful information to improve the performance of tori lines. Based on the seabird behaviour, it is recommended that tori lines should have a minimum aerial coverage of 50 m. Copyright © 2012 John Wiley & Sons, Ltd.
5.
A depth and temperature data logger was deployed by air gun on an individual Baird’s beaked whale (Berardius bairdii) off the Pacific coast of Japan. The retrieved data logger recorded 81 dives over approximately 29 h. The maximum recorded depth and the longest dive duration were 1777 m and 64.4 min, respectively. All dives were classified into three categories by depth: deep dives (>1000 m), intermediate dives (100–1000 m), and shallow dives (<100 m). Several intermediate dives generally followed a deep dive, and sequential shallow dives followed several intermediate dives in the record of the Baird’s beaked whale. 相似文献
6.
- Scuba (self ‐ contained underwater breathing apparatus) diving can act as an incentive ‐ based conservation mechanism and protect reefs by funding conservation and replacing more consumptive uses. However, diving must be sustainable.
- One challenge to sustainability is changing reef conditions and diving clientele over time. This paper examines these changes with respect to diving on the Andaman coast of Thailand using a Wildlife Tourism Model.
- In 2012 a questionnaire was administered to 591 scuba divers and compared with 506 questionnaires collected in 2000. Findings include:
- the 2012 industry has a higher proportion of low and medium specialization visitors that have lower expectations and lower overall satisfaction, yet remain willing to return;
- the average per capita economic contribution of divers to the local economy and to dive companies declined by more than 30% by 2012;
- Andaman coast diving continued to grow in 2012, dominated by mass ‐ market tourism that had diversified into several niches;
- the results verify the use of the Wildlife Tourism Model as a tool to understand industry sustainability, and suggest further development of the model to capture the extension into specific, niche markets.
- Changes to diver characteristics in 2012 restrict the ability of diving to fund conservation, provide alternative livelihoods, support environmental choices by operators, and control dive pressure exerted on reefs.
- Results suggest the operationalization of Limits of Acceptable Change by both managers and dive operators to grow the conservation value of diving.
- The results of this study suggest that the Wildlife Tourism Model can be used to inform management choices in emerging dive destinations. For instance, creating spatial zones that target the tourist composition most appropriate to meet the conservation goals of each reef system.
7.
Nina Dehnhard Maud Poisbleau Laurent Demongin Katrin Ludynia Miguel Lecoq Juan F. Masello Petra Quillfeldt 《水产资源保护:海洋与淡水生态系统》2013,23(5):777-789
- Anthropogenic changes in the marine environment and global climate change have led to population declines in several seabird species worldwide. Rockhopper penguins (Eudyptes chrysocome and Eudyptes moseleyi) have experienced a dramatic population decline, potentially linked to increasing sea surface temperatures (SST). Among Southern Ocean diving seabirds, rockhopper penguins typically occupy a low trophic level, and might therefore be expected to mirror climate‐driven bottom‐up changes to the food web sensitively and on a short time scale.
- Using passive integrated transponders, survival rates of adults in a colony of southern rockhopper penguins (E. chrysocome) on the Falkland Islands were monitored over five consecutive years. Mean annual survival rates were in the range 84 to 96%.
- These values are high compared with other crested penguin species and reflect the generally good conditions during the study period, when low SST prevailed. However, survival rates were lower in 2010, corresponding to very cold conditions. Curve fits showed a best‐fit quadratic relationship between average SST anomaly and survival rates for the present data, as well as for a data set including two additional years from a different study at Staten Island.
- Results of this study suggest that rockhopper penguins survive best at SSTs that are lower than the average of the last four decades. In accordance with previously observed rockhopper penguin population declines, the present data suggest that rockhopper penguins are highly sensitive to changes in SST and their effects on the food web, a worrying perspective in times of global climate change. It seems likely that these changes could, in the long term, also affect population trends of other seabird species with similar ecological preferences.
- The most promising conservation approach should aim at enhancing ecosystem resilience, mainly by reducing industrial fishing and oil exploitation. This would allow the currently over‐exploited fish and squid stocks to recover, offering larger food resources to seabirds and other vertebrate species.
8.
Roshan Hanamseth G. Barry Baker Sally Sherwen Mark Hindell Mary‐Anne Lea 《水产资源保护:海洋与淡水生态系统》2018,28(1):175-181
- Gillnets are used widely in fisheries throughout the world and known to cause the death of thousands of seabirds each year. Currently few practical or technical options are available to fishers for preventing seabird mortalities.
- The ability of little penguins (Eudyptula minor) to differentiate between different coloured netting materials was tested under controlled conditions to ascertain if changes in gillnet colour could facilitate a potential mitigation measure by improving visibility of nets.
- The study involved a repeated‐measures design with penguins exposed to variously coloured mono‐filament threads creating a gillnet mimic. The gillnet mimic was made up of gillnet material configured as a series of vertical lines 25 mm apart stretched tightly across a stainless steel frame that measured 1160 mm × 1540 mm and divided into two equal panel areas. The panels were placed in a large tank within an enclosure that housed 25 penguins. Penguins were able to readily access the tank and swim freely. The frame was always introduced into the tank with one panel containing a gillnet mimic, and the other panel left empty as a control.
- Gillnet filament colours tested were clear, green and orange. Orange coloured monofilament lines resulted in lower collision rates (5.5%), while clear and green monofilament lines resulted in higher rates of collision (35.9% and 30.8%, respectively).
- These results suggest that orange‐coloured lines were more apparent to the birds. Constructing nets of orange‐coloured material may be effective in reducing bycatch in gillnets set in shallow waters and high light levels where seabirds are able to identify fine colour differences.
- Further testing under experimental conditions, accompanied with at‐sea trials to verify effectiveness in varied light conditions is warranted, together with an assessment of the effect of gillnet colour on catch efficiency of target species.
9.
Young Pacific bluefin tuna Thunnus orientalis with archival tags were released in the East China Sea. Time-series data for depth, and ambient and peritoneal temperatures
for nine fish, recorded every 128 s, were analyzed. Our objectives were to describe monthly changes in diving patterns in
relation to the ambient thermal structure and the occurrence of feeding events during March–June, and to discuss possible
reasons why bluefin tuna repeatedly dived to depths below the thermocline in terms of their thermoconservation mechanisms.
It was found that the fish repeatedly dived through the thermocline at intervals of 1.2 h on average, and the dive frequency
was high during March–May. However, the dive frequency and periodicity decreased in June, when the gradient became steeper.
In contrast, feeding events increased in June. These results indicate that from March to May, bluefin tuna repeatedly dive
because food biomass is inadequate at the surface, and they stop undertaking repeated dives in June when food becomes more
readily available at the surface, in addition to low visibility caused by low solar radiation. Further, the range of heat
transfer times for these fish was so long that their peritoneal temperature was probably maintained by engaging in brief dives.
The periodicity of dives may lead to a lower fluctuation in the peritoneal temperature, suggesting that the dives are a kind
of behavioral thermoregulation. 相似文献
10.
Tori‐lines with weighted branch lines reduce seabird bycatch in eastern South Pacific longline fishery 下载免费PDF全文
Noriyosi Sato Nobuhiro Katsumata Kosuke Yokota Takayoshi Uehara Ippei Fusejima Hiroshi Minami 《水产资源保护:海洋与淡水生态系统》2016,26(1):95-107
- The effectiveness of tori‐lines combined with double‐weighted branch lines in reducing seabird bycatch was evaluated in a pelagic longline fishery.
- Seabird bait attack behaviour, bycatch number, and sinking rate of baited hooks were examined on double‐weighted and unweighted branch lines deployed on the same longline with a single tori‐line. Comparisons were conducted from July to October in 2011 during two cruises on a chartered longline vessel in the eastern South Pacific Ocean outside the Chilean and Peruvian exclusive economic zones.
- Cape petrels (Daption capense), white‐chinned petrels (Procellaria aequinoctialis) and Westland petrels (Procellaria westlandica) were abundant during line setting. There were 275 primary bait‐taking attacks by these species, but there were only eight primary attacks by albatrosses. Nevertheless, six albatrosses and six diving seabirds were incidentally caught as bycatch. Of the primary attacks by Cape petrels, white‐chinned petrels and Westland petrels, 153 led to secondary attacks. These results suggest that off Chile and Peru there is frequent secondary bycatch of albatrosses as a result of their stealing bait from Cape petrels and diving seabirds.
- Best‐fit models for the number of primary attacks and of bycatch included the weighted branch line; the use of weighted branch lines resulted in a lower number of primary attacks. Hooks on unweighted branch lines did not reach any of the benchmark depths (3, 5, and 10 m) within the aerial extent of the tori‐lines (the tori‐line remaining above the water surface), hooks on weighted branch lines reached 5 m depth within the aerial extent. These results suggest that, for the pelagic longline fishery off Chile and Peru, combining double‐weighted branch lines and tori‐lines reduces the bycatch more effectively than tori‐lines with unweighted branch lines.