共查询到20条相似文献，搜索用时 15 毫秒
1.
Giovanni Bearzi Stefano Agazzi Joan Gonzalvo Silvia Bonizzoni Marina Costa Annalise Petroselli 《水产资源保护:海洋与淡水生态系统》2010,20(5):549-559
- 1. Dolphins are often claimed to compete with fisheries, including through removal of substantial biomass. To calculate the biomass removed by fisheries and the degree of resource overlap with dolphins in a coastal area of Greece, estimates of dolphin abundance based on photographic capture–recapture were combined with an assessment of fishing effort and catch.
- 2. The estimated total biomass consumed annually by local dolphin populations – 15 short‐beaked common dolphins and 42 common bottlenose dolphins – was 15.5 and 89.8 tonnes, respectively. The total biomass removed by the local fishing fleet (307 fishing boats) was 3469.2 tonnes, i.e. about 33 times greater than that removed by dolphins.
- 3. Dolphins removed 2.9% of the total biomass, fisheries 97.1%. Nine purse seiners (representing only 3% of the active fishing fleet) were responsible for 31.9% of biomass removal. Similarity of biomass composition between dolphins and fisheries was expressed by a Pianka index of 0.46 for common dolphins and 0.66 for bottlenose dolphins.
- 4. Overlap differed according to fishing gear. Common dolphin overlap was higher with purse seiners (0.82), and lower with beach seiners (0.31), bottom trawlers (0.11) and trammel boats (0.06). There was virtually no overlap with longliners (0.02). Bottlenose dolphin overlap was higher with trammel boats (0.89) and bottom trawlers (0.75), and lower with longliners (0.38), purse seiners (0.24) and beach seiners (0.18). There was minimal overlap (0.12) between the two dolphin species.
- 5. This study suggests that ecological interactions between dolphins and fisheries in this coastal area have minor effects on fisheries. Conversely, prey depletion resulting from overfishing can negatively affect dolphins. Fisheries management measures consistent with national and EU legislation are proposed to ensure sustainability and to protect marine biodiversity. Copyright © 2010 John Wiley & Sons, Ltd.
2.
- Many species and populations of odontocetes have modified their behaviour to take advantage of feeding opportunities provided by fishing activities, with depredation of fishing gear being the most common type of adaptation.
- The northern Adriatic Sea has been identified as an important marine mammal area because of a regular occurrence of common bottlenose dolphins. Boat surveys were conducted within a 3,000 km2 sector of the Adriatic Sea off the coast of Veneto, Italy, between April and October 2018–2019. Based on 76 days at sea, 10,711 km of navigation, and 81 h 26 min of dolphin tracking, this study contributes novel quantitative information on dolphin spatial distribution, and on their occurrence in the wake of beam trawlers, otter trawlers, and midwater pair trawlers.
- A combined generalized additive model and generalized estimation equation framework indicated that trawling—along with other physiographic, biological and anthropogenic variables—influenced dolphin distribution. In days of trawling, the chance of encountering dolphins increased by ~4.5 times (95% confidence interval 1.8–11.0) near active beam trawlers, by ~16.0 times (7.1–36.0) near otter trawlers, and by ~28.9 times (12.0–69.6) near midwater pair trawlers.
- Spatial modelling was used to create maps of predicted distribution, suggesting differences in habitat use between trawling and no-trawling days. Spatial modelling for all days identified a dolphin distribution hotspot of 832 km2, situated off the Po river delta.
- Evidence contributed by this study can be used to inform management action within one of the world's areas most heavily impacted by fishing and other human encroachment. Such management action would help enforce the European Union's Habitats Directive and Marine Strategy Framework Directive, while also informing EU's Maritime Spatial Planning.
3.
Giovanni Bearzi Elena Politi Stefano Agazzi Sebastiano Bruno Marina Costa Silvia Bonizzoni 《水产资源保护:海洋与淡水生态系统》2005,15(3):243-257
- 1. Boat surveys aimed at studying short‐beaked common dolphins and common bottlenose dolphins in eastern Ionian Sea coastal waters were conducted between 1993 and 2003. During 835 survey days, 24 771 km of total effort was distributed within an area of 480 km2, resulting in 428 common dolphin and 235 bottlenose dolphin sightings.
- 2. Individual photo‐identification was performed extensively throughout this study, making it possible to monitor the number of animals seen in the study area each year and their long‐term residency patterns.
- 3. Common dolphins declined across the study period, from 2.18 encounters/100 km in 1997 to 0.40 encounters/100 km in 2003. In contrast, there was a relatively stable presence of bottlenose dolphins, some individuals showing high levels of site fidelity and others using the area only occasionally.
- 4. The local decline of common dolphins and the low density of bottlenose dolphins appeared to reflect the general status of these cetacean species in the wider Mediterranean region, where common dolphins were classified as endangered in the IUCN Red List in 2003.
- 5. Based on the available evidence, we infer that the present unfavourable status of common dolphins in eastern Ionian Sea coastal waters is largely a consequence of prey depletion.
4.
Giuseppa Buscaino Maria Ceraulo Giuseppe Alonge Daniela Silvia Pace Rosario Grammauta Vincenzo Maccarrone Angelo Bonanno Salvatore Mazzola Elena Papale 《水产资源保护:海洋与淡水生态系统》2021,31(8):2241-2256
- Dolphins interact with many types of fishing gear, causing damage to fishing activities and in some cases facing harm and becoming entangled as bycatch.
- In this study, the behaviour of bottlenose dolphins during their interaction with set nets, equipped with and without interactive pingers, was investigated. Acoustic monitoring of the nets was conducted for a total of 56 hauls and 814.9 hr of recordings, from the 16 October to 13 November 2015, along the coast of Lampedusa island (Sicilian Channel, Italy, Mediterranean Sea).
- The level of interaction between dolphins and the nets was evaluated considering the number of dolphin clicks grouped over time (single acoustic incursion on each net), the duration of every acoustic incursion, and the number of dolphin clicks per incursion. Moreover, the catch rate was measured as the number of fish per hour for each net.
- Based on the recording time of dolphin clicks, the spatio-temporal development of the interaction with the nets located in different bays of the island was assessed.
- The duration of the interaction between dolphins and nets significantly increased over the study period, with a concomitant reduction in catch rate. The interactive pinger showed efficacy in protecting the nets from dolphin depredation during the first period of 36 hauls and 11 fishing days (higher catch rates and lower incursion durations), whereas no differences were found in any interaction parameters between pinger and control nets in the second period (20 hauls and six fishing days).
- Interactive pingers may be an effective, short-term (2–3 weeks) tool in deterring depredation by bottlenose dolphins in small-scale artisanal fisheries. Other mitigation approaches, such as gear modification, lessons learned through outreach, and passive acoustic monitoring of the nets, could improve the management of the interactions between fisheries and bottlenose dolphins.
5.
6.
Cristina Milani Adriana Vella Pavlos Vidoris Aristidis Christidis Emmanouil Koutrakis 《水产资源保护:海洋与淡水生态系统》2021,31(Z1):76-86
- The abundance, distribution and diet of the short-beaked common dolphin were investigated as part of the first detailed study on cetacean populations in the North Aegean Sea. Since 2004, the area has been proposed by national and international entities as a marine protected area for common dolphins and other cetacean species owing to its high biodiversity.
- Abundance and distribution were investigated between 2005 and 2013 through dedicated scientific marine transect surveys, covering 14,701 km, in sea conditions of Beaufort sea state 3 and below. The line-transect sampling method was used to estimate relative abundance, using Distance 6.0 software. Encounter rate for this species in the study area was estimated to be 0.24 groups/100 km (1.5 dolphins/100 km), with a mean group size of 6.88 (SE = 1.90).
- Common dolphin sightings were analysed for correlations with eight environmental variables (distance from the coast, depth, slope, median salinity, gradient of salinity, median temperature, gradient of temperature and mean current) using generalized additive modelling. Common dolphin sightings were significantly correlated to depth, temperature and salinity.
- Stomach-content analyses were performed on eight suitable samples from common dolphins stranded in the study area. The trophic level of the species was calculated, indicating that this species is a top predator.
- This research provides the first estimates for abundance and distribution and the first diet analysis for this Mediterranean Endangered dolphin species in the study area based on a year-round long-term study.
7.
Alexandre Gannier 《水产资源保护:海洋与淡水生态系统》2021,31(Z1):61-68
- Common dolphin distribution in the western Mediterranean is still poorly known, with the exception of the Alboran Sea. In French waters, the species occurrence is suspected to have strongly decreased during the 20th century.
- Small boat dedicated surveys from 1988 to 2012 were undertaken to describe common dolphin distribution in five regions of French waters and three southern regions of the western basin. A total survey effort of 38,561 km resulted in sightings of 25 common dolphin groups in the western basin.
- Common dolphins were rarely observed off the French continental coast, more frequently around Corsica, and were quite frequent in waters off western Sardinia. Their most favoured habitat was found to be in neritic or upper slope waters.
- The analysis of stranding records suggested that common dolphins were more abundant in French inshore waters prior to 1980.
- A major increase of pelagic fish landings occurred from the beginning of the 1960s in the western part of French waters. Local populations of common dolphins may have declined as a consequence of prey depletion.
8.
- 1. Nine cetacean species have been reliably reported to occur in the shallow northern Adriatic Sea since the 17th century. However, only two species were considered regular there until the 1970s: the short‐beaked common dolphin (Delphinus delphis) and the common bottlenose dolphin (Tursiops truncatus).
- 2. Short‐beaked common dolphins have progressively disappeared from the northern Adriatic and are now rare in the region. The systematic culling campaigns and other takes that occurred between the second half of the 18th century and the 1960s, and habitat degradation in subsequent years are the most likely causes of their decline.
- 3. Today, common bottlenose dolphins are the only regular component of the northern Adriatic cetacean fauna; however, they now occur at low densities, and their fragmented groups are facing significant anthropogenic threats.
- 4. The future of northern Adriatic dolphins will depend on precautionary action to prevent further decline and on intensified research effort aimed at identifying the most effective mitigation strategies.
9.
- The Mediterranean common dolphin (Delphinus delphis), considered to have been very common in the past, had undergone a dramatic decline across most of the basin by the end of 1970s. In the northern Adriatic Sea, one of the regions with most available historical information, the common dolphin is thought to have been the most common and abundant cetacean throughout most of the 20th century. However, by the end of 1970s, it had virtually disappeared from the region and is now considered generally absent from the entire Adriatic Sea.
- This contribution summarizes the occurrence of common dolphins in the Gulf of Trieste and provides a brief review of published records in other parts of the Adriatic Sea.
- Systematic boat surveys in the wider area of the Gulf of Trieste between 2002 and 2019 confirmed that the common bottlenose dolphin (Tursiops truncatus) is the only regularly occurring cetacean species in this area. Despite this, several records of common dolphins were documented in the Gulf of Trieste between 2009 and 2012, through sightings of live animals or recovery of dead stranded animals.
- Dorsal fin markings allowed the photo-identification of some of these, suggesting that at least four different live individuals (three adults and one calf) occurred here in recent times. Most cases involved single adult individuals, but one included a mother-calf pair that was temporarily resident in a port for several months, a behaviour atypical for this species. Photo-identification showed that the presumed mother had previously been sighted in the Ionian Sea in Greece, over 1,000 km from the Gulf of Trieste, making this the longest documented movement for this species worldwide.
- At present, the common dolphin continues to be rare in the region.
10.
Guido Gnone Michela Bellingeri Frank Dhermain Franck Dupraz Silvio Nuti Davide Bedocchi Aurelie Moulins Massimiliano Rosso Jessica Alessi Rachel S. McCrea Arianna Azzellino Sabina Airoldi Nicola Portunato Sophie Laran Lea David Nathalie Di Meglio Patrizia Bonelli Gionata Montesi Roberta Trucchi Fulvio Fossa Maurizio Wurtz 《水产资源保护:海洋与淡水生态系统》2011,21(4):372-388
11.
12.
13.
- Marine aquaculture, and its fast-growing development, has the potential for wider environmental, ecosystem, and biodiversity impacts. This study assesses the impact of fish farming on a bottlenose dolphin (Tursiops truncatus) population within the Gulf of Ambracia (western Greece) between 2007 and 2018. Two different study areas were defined in order to investigate differences on occurrence, abundance, behaviour, and seasonal fluctuations between them: a ‘control area’, in the north-western side of the Gulf; and a ‘fish farm area’, in the south west, where the highest density of fish farm cages is found.
- A total of 169 daily surveys were dedicated to the control area and 74 days were dedicated to the fish farm area, yielding 104 and 37 sightings, respectively. Both the probability of detecting dolphins (U = 6,763.000, P = 0.002) and the group sizes (U = 578.000, P < 0.001) were smaller around fish farms.
- Seasonality analyses were restricted to 2007–2008, as this was the period with year-round effort. Results revealed that dolphins were more frequently seen around fish farms in the winter (Kruskal–Wallis test, P = 0.036).
- From the 40 identified individuals that were re-sighted at least 10 times during the study period, 21 used the fish farm area less than expected according to sampling effort, and 10 of them were never observed in that area (binomial test, P < 0.05).
- The results revealed an impact of fish farms on the distribution of bottlenose dolphins in the Gulf of Ambracia. This information should be taken into consideration when defining ecosystem-based management measures within the management plan, which is currently in preparation for this Natura 2000 site.
14.
15.
16.
Anna B. Giles Paul A. Butcher Andrew P. Colefax Dan E. Pagendam Maddison Mayjor Brendan P. Kelaher 《水产资源保护:海洋与淡水生态系统》2021,31(3):677-684
- Recent advances in aerial drones offer new insights into the biology, ecology and behaviour of marine wildlife found on or near the ocean’s surface. While opening up new opportunities for enhanced wildlife monitoring, the impacts of drone sampling and how it might influence interpretations of animal behaviour are only just beginning to be understood.
- The capacity of drones to record bottlenose dolphin (Tursiops spp.) behaviour was investigated, along with how the presence of a small drone at varying altitudes influences dolphin behaviour. Over 3 years and eight locations, 361 drone flights were completed between altitudes of 5 and 60 m above the ocean.
- Analyses showed that dolphins were increasingly likely to change behaviour with decreasing drone altitude. A positive correlation was also found between time spent hovering above a group of dolphins and the probability of recording a behavioural response. Dolphin group size also influenced the frequency of an observed behavioural change, displaying a positive correlation between behaviour change and group size.
- Overall, although drones have the potential to impact coastal dolphins when flown at low altitudes, they represent a useful tool for collecting ecological information on coastal dolphins owing to their convenience, low cost and capacity to observe behaviours underwater. To maximize benefits and minimize impacts, this study suggests that drones should be flown 30 m above coastal bottlenose dolphins.
17.
Nicole L. Vollmer Patricia E. Rosel Keith D. Mullin Lori H. Schwacke Lance P. Garrison Brian C. Balmer Kevin Barry Anthony Martinez Brian M. Quigley Carrie Sinclair Todd R. Speakman Jesse Wicker Lynsey Wilcox Eric S. Zolman 《水产资源保护:海洋与淡水生态系统》2021,31(10):2951-2966
- Population structure of highly mobile marine organisms can be complex and difficult to study, but it is important to understand how populations partition themselves within their environment for accurate assessment of both natural and anthropogenic impacts and successful management. The 2010 Deepwater Horizon oil spill negatively impacted common bottlenose dolphins (Tursiops truncatus) within Mississippi Sound and the surrounding north central Gulf of Mexico (GOMx); however, little was known about their underlying population structure in these waters. Thus, it was unclear how many demographically independent populations were affected by the spill.
- Common bottlenose dolphin samples were collected throughout inshore waters of Mississippi Sound and coastal waters of the north-central GOMx. Mitochondrial DNA control region sequence data and 19 nuclear microsatellite loci were analysed to determine how many populations are present and characterize their range throughout these waters.
- Bayesian clustering and migration analyses identified two genetically distinct and demographically independent populations: one predominantly inhabiting Mississippi Sound and adjacent coastal waters, and a second population extending generally from offshore of Mobile Bay, Alabama, east along the Florida Panhandle. Neither of these populations align with the currently delineated management stocks previously used to estimate impacts from the oil spill on common bottlenose dolphins in this portion of the GOMx.
- These results suggest that revisions may be necessary so that management stocks accurately represent the demographically independent populations present in these waters. Furthermore, better comprehension of underlying population structure will enhance impact assessments on common bottlenose dolphins and provide more appropriate baseline data to support future restoration and conservation objectives.
18.
19.
Linking small pelagic fish and cetacean distribution to model suitable habitat for coastal dolphin species,Delphinus delphis and Tursiops truncatus,in the Greek Seas (Eastern Mediterranean) 
下载免费PDF全文
下载免费PDF全文 Marianna Giannoulaki Evangelia Markoglou Vasilis D. Valavanis Paraskevi Alexiadou Anna Cucknell Alexandros Frantzis 《水产资源保护:海洋与淡水生态系统》2017,27(2):436-451
- 相似文献