Interannual Differences for Sea Turtles Bycatch in Spanish Longliners from Western Mediterranean Sea

Recent studies showed that regional abundance of loggerhead and leatherback turtles could oscillate interannually according to oceanographic and climatic conditions. The Western Mediterranean is an important fishing area for the Spanish drifting longline fleet, which mainly targets swordfish, bluefin tuna, and albacore. Due to the spatial overlapping in fishing activity and turtle distribution, there is an increasing sea turtle conservation concern. The main goal of this study is to analyse the interannual bycatch of loggerhead and leatherback turtles by the Spanish Mediterranean longline fishery and to test the relationship between the total turtle by-catch of this fishery and the North Atlantic Oscillation (NAO). During the 14 years covered in this study, the number of sea turtle bycatches was 3,940 loggerhead turtles and 8 leatherback turtles, 0.499 loggerhead turtles/1000 hooks and 0.001014 leatherback turtles/1000 hooks. In the case of the loggerhead turtle the positive phase of the NAO favours an increase of loggerhead turtles in the Western Mediterranean Sea. However, in the case of leatherback turtle the negative phase of the NAO favours the presence of leatherback turtle. This contraposition could be related to the different ecophysiological response of both species during their migration cycle.

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Validating an ecological model with fisheries management applications: the relationship between loggerhead by-catch and distance to the coast

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s002531541000069x ◽

2010 ◽

Vol 91 (6) ◽

pp. 1381-1383 ◽

Cited By ~ 5

Author(s):

José C. Báez ◽

Raimundo Real ◽

Jesús Bellido ◽

David Macias ◽

José M. de la Serna ◽

...

Keyword(s):

Ecological Model ◽

Loggerhead Turtle ◽

Sea Turtle ◽

Fishing Effort ◽

Western Mediterranean ◽

Fishing Activity ◽

Incidental Capture ◽

Western Mediterranean Sea ◽

Balearic Sea ◽

By Catch

On the one hand, a recent study on sea turtle by-catch during surface longline fishing targeting swordfish in the western Mediterranean Sea showed that sea turtle by-catch is independent of fishing effort and other technological factors. When the distance to the coast increases, there is a higher probability of catching a loggerhead turtle. The authors proposed to avoid fisheries further than 35 nautical miles (approximately 65 km) from the coast. However, the proposed 35 nautical miles limit could be useful where the continental shelf is narrow, as in the Balearic Sea, and useless where it widens. On the other hand, ecological model validation is considered essential for management application. The objective of the present paper is to validate the new fisheries loggerhead by-catch model in different areas outside the Balearic Sea with wider continental shelves, aimed at maintaining sustainable fishing activity compatible with the conservation of the loggerhead populations. Our present results validate the previous model, and stress the importance of the eco-geographical variable distance to the coast in understanding the loggerhead by-catch (or incidental capture) per unit effort for the longline fisheries targeting swordfish.

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Helminth communities of loggerhead turtles (Caretta caretta) from Central and Western Mediterranean Sea: The importance of host's ontogeny

Parasitology International ◽

10.1016/j.parint.2010.04.009 ◽

2010 ◽

Vol 59 (3) ◽

pp. 367-375 ◽

Cited By ~ 23

Author(s):

Mario Santoro ◽

Francisco J. Badillo ◽

Simonetta Mattiucci ◽

Giuseppe Nascetti ◽

Flegra Bentivegna ◽

...

Keyword(s):

Mediterranean Sea ◽

Caretta Caretta ◽

Western Mediterranean ◽

Western Mediterranean Sea ◽

Helminth Communities ◽

Loggerhead Turtles

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Differential distribution within longline transects of loggerhead turtles and swordfish captured by the Spanish Mediterranean surface longline fishery

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315407054744 ◽

2007 ◽

Vol 87 (3) ◽

pp. 801-803 ◽

Cited By ~ 17

Author(s):

José C. Báez ◽

Raimundo Real ◽

Juan A. Camiñas

Keyword(s):

Loggerhead Turtle ◽

Western Mediterranean ◽

Differential Distribution ◽

Chi Square ◽

Western Mediterranean Sea ◽

Loggerhead Turtles ◽

Chi Square Test ◽

Incidental Catch ◽

By Catch ◽

The Relationship

Surface longline targeting mainly swordfish is considered a major threat for loggerhead turtle populations in the western Mediterranean Sea. For this reason, it is necessary to analyse the relationship between the characteristics of longline sets and loggerhead turtle by-catch. The objective of this study is to look for differential spatial distribution of loggerhead turtle and swordfish captures along the longline to gain insights that might be useful to diminish unintended, incidental catch of turtles without affecting the captures of the target species.Longlines are divided into transects separated by two consecutives buoys. During the 1999 fishing period of the traditional (without roller) Spanish surface drifting longline fleet (August to November), 59 technically homogeneous fishing operations, composed of 23 sections each, were observed. Chi-square test was used to compare loggerhead turtle and swordfish distributions among transects with those expected at random. Significant differences were obtained only for loggerhead turtles, with 93% of the specimens caught in the second half of the longline transects, which were retrieved from the sea during daytime. Significant differences were not found for the swordfish along the whole longline or for loggerhead turtle captures retrieved during daytime. We conclude that swordfish captures are independent of retrieval time whereas the incidental catch of loggerhead turtles occurs mainly during daytime, probably because loggerhead turtles use vision to locate baits.

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By-catch frequency and size differentiation in loggerhead turtles as a function of surface longline gear type in the western Mediterranean Sea

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315412001841 ◽

2013 ◽

Vol 93 (5) ◽

pp. 1423-1427 ◽

Cited By ~ 11

Author(s):

José Carlos Báez ◽

David Macías ◽

Juan Antonio Camiñas ◽

José María Ortiz de Urbina ◽

Salvador García-Barcelona ◽

...

Keyword(s):

Mediterranean Sea ◽

Sea Turtle ◽

Western Mediterranean ◽

Catch Per Unit Effort ◽

Size Selectivity ◽

Loggerhead Turtles ◽

The Mediterranean ◽

By Catch ◽

Catch Rates ◽

The Impact

Fisheries by-catch is considered to be a major threat to loggerhead turtles in the Mediterranean Sea. Technical differences in both gear configurations (e.g. hook and bait type) and fisheries operations carried out by the Spanish Mediterranean surface longline fleet could have an effect on by-catch rates and size selectivity. The aim of the present study was to test the differences in by-catch per unit effort and body size of loggerhead sea turtles caught using different gear types in the Mediterranean surface longline fishery. Our results suggest that differences in the gear type used have an effect on catch rates and size selectivity. Thus, surface longliners targeting albacore (LLALB) using smaller hooks tend to capture smaller loggerheads but have the highest by-catch per unit of effort (BPUE), whereas other longlines, such as surface longliners targeting bluefin tuna (LLJAP) and traditional surface longliners targeting swordfish (LLHB), using larger hooks tend to select the larger animals; moreover, LLHB had the lowest BPUE. Disproportionate rates of fisheries-induced mortality on certain size/age-classes can differentially affect sea turtle populations, as each sea turtle age-class contributes differently to current and future reproduction. Thus, fisheries management should not only be focusing on preserving the large juvenile and mature turtles, but also on reducing the total by-catch. Thus, we recommend encouraging the use of LLHB versus other surface gears. We suggest that it is very important to take into account the gear type (and its particular catch rates) when making inferences about the impact of longline fisheries on sea turtle populations.

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Late Pleistocene sedimentation in the Western Mediterranean Sea: implications for productivity changes and climatic conditions in the catchment areas

Palaeogeography Palaeoclimatology Palaeoecology ◽

10.1016/s0031-0182(02)00602-8 ◽

2003 ◽

Vol 190 ◽

pp. 121-137 ◽

Cited By ~ 39

Author(s):

Syee Weldeab ◽

Wolfgang Siebel ◽

Rolf Wehausen ◽

Kay-Christian Emeis ◽

Gerhard Schmiedl ◽

...

Keyword(s):

Mediterranean Sea ◽

Late Pleistocene ◽

Western Mediterranean ◽

Climatic Conditions ◽

Western Mediterranean Sea ◽

Catchment Areas

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Variation in spatial distribution of juvenile loggerhead turtles in the eastern Atlantic and western Mediterranean Sea

Journal of Experimental Marine Biology and Ecology ◽

10.1016/j.jembe.2009.03.007 ◽

2009 ◽

Vol 373 (2) ◽

pp. 79-86 ◽

Cited By ~ 37

Author(s):

Catalina Monzón-Argüello ◽

Ciro Rico ◽

Carlos Carreras ◽

Pascual Calabuig ◽

Adolfo Marco ◽

...

Keyword(s):

Spatial Distribution ◽

Mediterranean Sea ◽

Western Mediterranean ◽

Western Mediterranean Sea ◽

Loggerhead Turtles

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First study of sea turtle strandings in Algeria (western Mediterranean) and associated threats: 2016–2017

Herpetozoa ◽

10.3897/herpetozoa.33.e48541 ◽

2020 ◽

Vol 33 ◽

pp. 113-120

Author(s):

Alae Eddine Belmahi ◽

Youcef Belmahi ◽

Mouloud Benabdi ◽

Amaria Latefa Bouziani ◽

Samira Ait Darna ◽

...

Keyword(s):

Chelonia Mydas ◽

Sea Turtle ◽

Western Mediterranean ◽

Dermochelys Coriacea ◽

Adult Size ◽

The West ◽

Loggerhead Sea Turtle ◽

Leatherback Turtle ◽

Loggerhead Turtles ◽

Algerian Coast

Between December 2015 and December 2017 a total of 63 sea turtles were recorded as being stranded along the Algerian coast. The loggerhead sea turtle Caretta caretta was the most commonly stranded species (n = 44) (69.8%), followed by the leatherback Dermochelys coriacea (n = 18) (28.6%) and the green turtle Chelonia mydas (n = 1). There was a slight dominance of the adult size class for stranded loggerhead turtles, while, for the leatherback, late juveniles and adults prevailed. Most loggerhead turtles stranded during the summer months (July and August), whereas most leatherbacks stranded during winter. The breakdown of the strandings by region shows a slight dominance along the western and central shores for C. caretta and a clear dominance in the west for D. coriacea. The primary cause of death was determined in 50.8% of the stranded turtles. Regarding the evidence of interactions with humans the major cause of stranding in loggerhead turtles was incidental catch by artisanal fisheries, followed by boats’ collisions. The main causes of leatherback strandings were boats’ collisions. Algerian data show that human activities affect loggerhead turtles and also prove a significant presence of the leatherback turtle on this coast.

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New fossil sea turtle trackway morphotypes from the Pleistocene of South Africa highlight role of ichnology in turtle paleobiology

Quaternary Research ◽

10.1017/qua.2019.40 ◽

2019 ◽

Vol 92 (3) ◽

pp. 626-640 ◽

Cited By ~ 3

Author(s):

Martin G. Lockley ◽

Hayley C. Cawthra ◽

Jan C. De Vynck ◽

Charles W. Helm ◽

Richard T. McCrea ◽

...

Keyword(s):

South Africa ◽

Late Pleistocene ◽

Sea Turtles ◽

Loggerhead Turtle ◽

Sea Turtle ◽

Climatic Conditions ◽

South Coast ◽

Freshwater Turtles ◽

Leatherback Turtle

AbstractMore than 130 late Pleistocene trackway sites from the coastal eolianites and beach deposits of the Cape south coast, South Africa, have previously mostly yielded tracks of large mammals and birds. However, two sites east of Still Bay, and a third near Garden Route National Park, yield distinctive trackways of hatchling sea turtles, made during the short posthatching (postemergence) interval when the trackmakers headed for the sea. One assemblage of approximately parallel trackways indicates smaller loggerhead turtle hatchlings, with alternating gaits, and contrasts with a wider trackway indicating a leatherback turtle hatchling. These are the world's first reports of fossil traces that document this brief “run-for the-sea” phenomenon. They help delineate late Pleistocene sea turtle breeding ranges and indicate climatic conditions along the Cape south coast. Ichnotaxonomically defined swim tracks of large adult sea turtles are known from a few Mesozoic sites. Likewise, walking and swim traces of terrestrial freshwater turtles are also known from the Mesozoic and Cenozoic. However, as no ichnotaxonomy exists for these diagnostic hatchling trails, we assign the trackways of the inferred loggerheads to the new ichnotaxon Australochelichnus agulhasii ichnogen. et ichnosp. nov., and the inferred leatherback trackway to Marinerichnus latus ichnogen. et ichnosp. nov.

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