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Annual survival probabilities of juvenile loggerhead sea turtles indicate high anthropogenic impact on Mediterranean populations 
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下载免费PDF全文 Paolo Casale Daniela Freggi Giovanni Furii Carola Vallini Pasquale Salvemini Michele Deflorio Giovanni Totaro Stefano Raimondi Caterina Fortuna Brendan J. Godley 《水产资源保护:海洋与淡水生态系统》2015,25(5):690-700
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- Tracking of juvenile sea turtles is a research priority to inform the protection of relevant habitats and ensure sustainable rates of recruitment into adult populations. Based on satellite tracking, mixed stock analysis, and mark–recapture studies, Drini Bay in the South Adriatic Sea, Central Mediterranean, has been confirmed as an important foraging site used by loggerhead turtles from all major rookeries in the Mediterranean subpopulation.
- Three juvenile loggerhead turtles (Caretta caretta) from Drini Bay were tracked for 763, 364, and 211 days respectively. All turtles exhibited different movement patterns.
- The two smaller turtles ranged widely beyond the bay. One of these (69.5 cm curved‐carapace length; CCL) used the coldest region of the Mediterranean during the first winter of tracking where mean weekly temperatures dipped below 12°C but moved southwards to warmer waters during the second winter. In comparison, the other (66 cm CCL) individual moved south to winter in warmer waters from the outset. Both individuals returned to Drini Bay during summer, demonstrating fidelity to the study site. The third turtle, which was larger (76 cm CCL), remained in Drini Bay for the duration of tracking. These results support the findings of other mark–recapture studies at Drini Bay, which have suggested that the foraging site is being used in a transient way by immature turtles.
- All three turtles preferentially used the shallow waters (<30 m) in the south of Drini Bay. The study demonstrates a high degree of overlap between the habitat use of the three tracked turtles and that of adult turtles tracked from nesting sites, and although based on a small sample size, contributes to a growing knowledge base regarding the wider habitat use of the Mediterranean loggerhead population.
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Luisa Garofalo Angela Mastrogiacomo Paolo Casale Rossella Carlini Claudia Eleni Daniela Freggi Donatella Gelli Leyla Knittweis Carmen Mifsud Toni Mingozzi Nicola Novarini Dino Scaravelli Giovanni Scillitani Marco Oliverio Andrea Novelletto 《水产资源保护:海洋与淡水生态系统》2013,23(6):868-884
- that the north Adriatic, the Tunisian continental shelf, the waters around Malta and the Italian Ionian Sea represent important areas for the conservation of rookeries in Greece, Libya and Turkey, respectively;
- that waters off the Italian peninsula and the islands of Lampedusa and Malta are mainly inhabited by individuals of Mediterranean origin, with a major contribution from the nearest and largest colonies, while Atlantic turtles are restricted to the western areas;
- that specific migratory routes exist from rookeries to foraging grounds;
- a poor bi‐parental genetic structuring, which suggests a high male‐mediated gene flow in the Mediterranean;
- mixing of small turtles in waters distant from natal rookeries, and recovery of structuring for large‐sized individuals; and
- that uncommon mtDNA haplotypes are more powerful markers than microsatellite alleles in assessing an individual's origin, owing to their higher geographic specificity.
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Paolo Casale Amedeo Ciccocioppo Giulia Vagnoli Alessandro Rigoli Daniela Freggi Livia Tolve Paolo Luschi 《水产资源保护:海洋与淡水生态系统》2020,30(1):123-130
- Spatio‐temporal distribution is fundamental information for species of conservation concern, like sea turtles, that are threatened by anthropogenic activities at sea such as fishing. While coarse‐scale distribution information is available for several sea turtle populations, fine‐scale distribution informing on hot‐spot areas for spatial management is more difficult to obtain.
- Here a citizen science approach involving tourism boats was undertaken to investigate the spatio‐temporal distribution of the loggerhead sea turtle (Caretta caretta) in the Pelagie Archipelago, located in a major foraging area for this species in the Mediterranean and where high fishing‐induced mortality occurs. The study was designed to provide data of absence and total sampling effort, commonly under‐reported in citizen science studies, allowing comparison among zones and periods. This was complemented by reports from fishing vessels.
- Tourism boats reported 584 loggerhead turtle sightings during 1718 daily trips and fishing vessels reported 280 loggerhead turtles captured during 1040 fishing days. The results indicate a strong heterogeneous distribution in the Archipelago, with a low turtle occurrence around the main island, Lampedusa, where the highest human presence and activity occur. This may represent rare evidence of displacement behaviour of turtles that is worth further investigation. This also suggests that the current small marine protected area around Lampedusa has a low conservation impact. Zones with higher loggerhead turtle occurrence appear to be in the south and the west parts of the Archipelago, suggesting that spatial management would be possible when relatively small hot‐spots have been identified through specific surveys.
- This study shows the potential of citizen science for providing preliminary information to guide more demanding and specific investigations. Such an approach may tremendously and rapidly improve the current knowledge on fine‐scale sea turtle distribution in regions with a great extension of coastlines and intensive tourist activities, such as the Mediterranean.
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Milagros Lpez‐Mendilaharsu Susan C. Gardner Jeffrey A. Seminoff Rafael Riosmena‐Rodriguez 《水产资源保护:海洋与淡水生态系统》2005,15(3):259-269
- 1. The conservation of highly mobile and migratory species remains one of the most serious challenges to resource managers.
- 2. Intense mortality of immature green turtles has been identified at principal developmental–feeding habitats in Baja California, and is considered a great threat to the stability of the eastern Pacific population. Thus, coastal lagoons of the Baja California peninsula, such as Bahía Magdalena, have been identified as high priority areas for their protection.
- 3. Conservation efforts to date have focused on creating a sea turtle refuge in the northwestern part of the bay, but this area may not be sufficient for protecting all of the critical feeding areas used by green turtles.
- 4. The diet of green turtles was investigated through analysis of digestive tract contents from 24 green turtles that were drowned incidentally in fishing nets at feeding grounds in Bahía Magdalena and adjacent areas along the Pacific coast of the Baja California peninsula, Mexico.
- 5. Mean straight carapace length (SCL) differed significantly between localities: mean: 55.5 cm (range: 47.7–76.9 cm, n=11) in Bahía Magdalena; mean: 67.7 >cm (range: 49–87 cm, n=11) in adjacent coastal waters.
- 6. Green turtle diet consisted largely of marine algae and seagrasses, but food items varied spatially. The red algae Gracilaria pacifica, Gracilariopsis lemaneiformis and Hypea johnstonii were the most abundant diet items inside Bahía Magdalena, and the seagrass Phyllospadix torreyi was the most commonly ingested food in coastal areas outside of the bay.
- 7. Results indicate that green turtles utilize spatially distinct foraging habitats within this region. Therefore, it is recommended that any design of protected areas for sea turtles in Bahía Magdalena should consider a regional approach instead of a local approach, taking into account the most important feeding areas used by green turtles at different life stages.
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Laura Prosdocimi Natalia S. Teryda Gabriela S. Navarro Raymond R. Carthy 《水产资源保护:海洋与淡水生态系统》2021,31(4):830-840
- Fisheries bycatch of non-target species in the commercial fleet is a major source of anthropogenic injury and mortality for sea turtles and marine megafauna.
- The Río de la Plata maritime front (RLPMF) and its adjacent international waters – comprising part of the Argentine and Uruguayan exclusive economic zones, is a highly important fishing ground in the south-western Atlantic Ocean as well as feeding and development grounds for sea turtles.
- This paper analyses the distribution of the bottom and pelagic trawling fishery within the RLPMF using information from Vessel Satellite Monitoring System. With this information, areas of highest trawling intensity were defined and further evaluated their overlap with sea turtle habitat-use areas from available sea turtle satellite tracking information.
- Results besides identifying high-susceptibility areas for sea turtle bycatch by the commercial trawler fleet along the RLPMF, provide predictive tools to identify vulnerable areas to interaction of sea turtles and the commercial fishing fleet.
- Implementation of bycatch mitigation measures, such as reduced fishing effort areas by the Argentine and Uruguayan fisheries management agencies has the potential to benefit the fisheries as well as marine megafauna. Furthermore, there is a need for additional research on the impact that this fleet can have on sea turtles present in the area.
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Giulia Cambiè 《水产资源保护:海洋与淡水生态系统》2011,21(1):28-36
- 1. Trammel nets are one important cause of sea turtle mortality resulting from incidental capture. This study presents findings over a 10‐year period during which loggerhead turtle by‐catch in trammel nets, set off the central west coast of Sardinia (Italy) in the summer months, was recorded by 17 fishing vessels.
- 2. Since the by‐catch registered represented counts of a rare event, data from the 17 vessels were used in the zero‐inflated Poisson (ZIP) model to determine the abundance of turtle by‐catch in trammel nets of the entire fleet, while a binomial generalized linear model was used to assess the probability of immediate survival for sea turtles incidentally caught in this gear.
- 3. The ZIP model quantified in about 45% the probability that 0.6 turtles have been caught by each vessel using trammel nets during summer over the 10‐year period. In addition, the model estimated a total of 916 by‐catch if the entire small‐scale fleet was to use trammel nets in the study area in the summers between 1992 and 2001, with a direct mortality rate of 69%.
- 4. The probability of immediate survival for sea turtles caught in trammel nets seems to be directly related to the size of the specimens caught; however, this relationship is plausible only when incidental capture in the net occurs shortly before gear retrieval.
- 5. The study area represents a region where the abundance of sea turtle by‐catch per vessel in trammel nets was much higher in July and August than in June and could represent a potential hot spot for the presence of juvenile loggerhead turtles, with high levels of interactions between the species and this fishing gear. Further research should better characterize the incidents of by‐catch and assess potential innovative solutions that allow small‐scale fisheries to coexist alongside sea turtles. Copyright © 2010 John Wiley & Sons, Ltd.
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- 1. A known fishing hot spot for loggerhead sea turtles (Caretta caretta) in the Mediterranean Sea is in the waters of the Strait of Sicily where interactions with fish hooks and branchlines are believed to be a major cause of mortality for sea turtles.
- 2. Hooks with different shapes but a similar gape width (circle hook size 16/0 vs J hook size 2) were tested in order to determine the potential effectiveness of the hook design to both reduce sea turtle capture as well as to maintain acceptable levels of target species capture rates in a shallow‐set longline swordfish fishery in the Mediterranean.
- 3. Seven experimental fishing trips, 30 000 hooks total, were conducted on a single commercial fishing vessel (18 m in length) in the Strait of Sicily during the months of July through October over a period of three years from 2005 to 2007. Circle and J hooks were alternated along the mainline.
- 4. A total of 26 sea turtles were hooked, all immature‐size Caretta caretta. Turtles were caught at a statistically greater frequency on J hooks than on circle hooks. The capture rate, weight, and upper jaw fork length of the target species were not significantly different between the two types of hooks employed.
- 5. Five sea turtles swallowed the hook and in all such cases these were J type. Circle hooks tended to be located externally and were more easily detected by fishermen, and could be removed with the correct dehooking action before returning the turtle to the sea.
- 6. These findings suggest that 16/0 circle hooks can effectively reduce the incidental capture of immature loggerhead sea turtles in a Mediterranean swordfish longline fishery without affecting the catch size of the target species.
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- 1. Drifting longlines are considered a major threat to endangered sea turtle populations worldwide. However, for a number of reasons, the mortality rate of captured turtles is not known with any certainty.
- 2. Information on 409 loggerhead turtles (Caretta caretta), collected during the day‐to‐day activities of a turtle rescue centre in Lampedusa island, central Mediterranean, in the period 2001–2005 has been analysed.
- 3. Observations indicate that: (i) drifting longlines are a major cause of mortality for sea turtles in the area; (ii) in addition to the hook, the piece of line attached to it (branchline) can easily cause death if it is long enough and well‐anchored; (iii) hooks and branchlines cause death in the short and long term, respectively; (iv) a turtle with a hook in the lower oesophagus/stomach has a very low chance of surviving the combined effect of hook and branchline; (v) the mortality of turtles with a hook in the mouth or higher oesophagus is probably important, though less than that of turtles with a hook in the lower oesophagus/stomach; (vi) in the study fishery, the average mortality of a turtle caught by a drifting longline is probably much higher than 30%.
- 4. Without specific investigations on the mortality of turtles with hooks in the mouth or higher oeasophagus, which are usually removed, the mortality induced by drifting longlines will remain unknown, preventing a full understanding of the effect on population growth and the real effectiveness of conservation measures such as use of different hooks and fishing depths, and proposals for adequate fishery management measures.
- 5. The number of turtles captured by drifting longlines should be drastically reduced, and because of the above uncertainty and the socio‐economic importance of the fishery sector, an ecosystem‐based management scheme should be promoted that is not limited to addressing only the turtle issue.
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Circle hook effectiveness for the mitigation of sea turtle bycatch and capture of target species in a Brazilian pelagic longline fishery 总被引：1，自引：0，他引：1
Gilberto Sales Bruno B. Giffoni Fernando N. Fiedler Venâncio G. Azevedo Jorge E. Kotas Yonat Swimmer Leandro Bugoni 《水产资源保护:海洋与淡水生态系统》2010,20(4):428-436
- 1. Incidental catches by the pelagic longline fishery is a major global threat for loggerhead (Caretta caretta) and leatherback (Dermochelys coriacea) sea turtles.
- 2. The reduction of incidental capture and post‐release mortality of sea turtles in the Brazilian pelagic longline fishery, operating in the south‐western Atlantic Ocean, was investigated by comparing the performance of 18/0 circle hooks with 9/0 J‐type (control) hooks. Hook selectivity experiments were performed between 2004 and 2008, in a total of 26 trips, 229 sets and 145 828 hooks. The experimental design included alternating control and experimental hooks along sections of the mainline.
- 3. An overall decrease in capture rates for loggerhead turtles of 55% and for leatherbacks of 65% were observed when using circle hooks. In addition, deep‐hooking in loggerheads decreased significantly from 25% using J‐hooks to 5.8% with circle hooks, potentially increasing post‐release survival.
- 4. Circle hooks increased catch rates of most of the main target species, including tunas (bigeye Thunnus obesus and albacore T. alalunga), and sharks (blue Prionace glauca and requiem sharks of the genus Carcharinus), with no difference in the capture rates of yellowfin tuna (T. albacares), shortfin mako shark (Isurus oxyrinchus), hammerhead sharks (Sphyrna lewini and S. zygaena), and dolphinfish or mahi mahi (Coryphaena hippurus). On the other hand, a significant decrease in the capture rate of swordfish (Xiphias gladius) was detected when using circle hooks.
- 5. Overall, results support the effectiveness of using circle hooks for the conservation of loggerhead and leatherback sea turtles, with positive effects on capture of most target species of the south‐western Atlantic longline fishery. Copyright © 2010 John Wiley & Sons, Ltd.
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