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

2013 ◽  
Vol 93 (5) ◽  
pp. 1423-1427 ◽  
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.

Trade and stowaways: molecular evidence for human-mediated translocation of eastern skinks into the western Mediterranean

2020 ◽  
Vol 41 (1) ◽  
pp. 49-62
Author(s):  
Josep Francesc Bisbal-Chinesta ◽  
Karin Tamar ◽  
Ángel Gálvez ◽  
Luís Albero ◽  
Pablo Vicent-Castelló ◽  
...  
Keyword(s):  
Iberian Peninsula ◽  
Mediterranean Sea ◽  
Western Mediterranean ◽  
Molecular Evidence ◽  
Long Distance ◽  
Human Movements ◽  
Allochthonous Species ◽  
The Mediterranean ◽  
Chalcides Ocellatus ◽  
The Impact

Abstract Human movements in the regions surrounding the Mediterranean Sea have caused a great impact in the composition of terrestrial fauna due to the introductions of several allochthonous species, intentionally or not. Reptiles are one of the groups where this anthropic impact is most evident, owing to the extensive intra-Mediterranean dispersals of recent chronologies. Chalcides ocellatus is a widespread skink with a natural distribution that covers almost the entire Mediterranean Basin. Two hypotheses have been proposed to explain its origin: natural dispersions and human translocations. Previous molecular data suggest the occurrence of a recent dispersal phenomenon across the Mediterranean Sea. In this study we present the first record of this species in the Iberian Peninsula, in Serra del Molar (South-east Spain). We combined molecular analyses and archaeological records to study the origin of this population. The molecular results indicate that the population is phylogenetically closely related to specimens from north-eastern Egypt and southern Red Sea. We suggest that the species arrived at the Iberian Peninsula most likely through human-mediated dispersal by using the trade routes. Between the Iron to Middle Ages, even now, the region surrounding Serra del Molar has been the destination of human groups and commercial goods of Egyptian origins, in which Chalcides ocellatus could have arrived as stowaways. The regional geomorphological evolution would have restricted its expansion out of Serra del Molar. These findings provide new data about the impact of human movements on faunal introductions and present new information relating to mechanisms of long-distance translocations.

Likely impacts of an eastward expansion of the inshore gill-net fishery in the Western Cape, South Africa: implications for management

2003 ◽  
Vol 54 (1) ◽  
pp. 39 ◽  
Author(s):  
K. Hutchings ◽  
S. J. Lamberth
Keyword(s):  
West Coast ◽  
Fishing Effort ◽  
Western Cape ◽  
Catch Per Unit Effort ◽  
South West ◽  
Gill Net ◽  
South West Coast ◽  
By Catch ◽  
Catch Rates ◽  
The Impact

Current South African government policy aims to create more equitable access to marine resources and there is pressure to increase the inshore gill-net fishing effort. At present, the gill-net fishery in the Western Cape is confined to the cool temperate west coast. In order to ascertain the potential catch if the fishery was to expand along the warm temperate south-west coast, a program of experimental netting was conducted. Estuarine and coastal marine sites were sampled bimonthly, using a range of commercial gill-nets (44–178 mm stretch-mesh). Although the target species, Liza richardsonii, dominated the catches, at least 33 of the by-catch species caught were also targeted by the commercial or recreational line-fish sectors. The number of species captured and the line-fish (by-catch) catch per unit effort (CPUE) were greatest in areas currently closed to the commercial gill-net fishery. Multivariate analysis indicated significant differences in catch rates and composition between exploited west coast and unexploited south-west coast sites. A combination of natural biogeographical trends and the impact of over 100 years of commercial gill-netting on the west coast are the likely causes of these differences. A spatial expansion of the gill-net fishery could have a detrimental impact on overexploited line-fish stocks and lead to increased user conflict.

scholarly journals Particulate biogenic barium tracer of mesopelagic carbon remineralization in the Mediterranean Sea (PEACETIME project)

2021 ◽  
Vol 18 (22) ◽  
pp. 5891-5902
Author(s):  
Stéphanie H. M. Jacquet ◽  
Christian Tamburini ◽  
Marc Garel ◽  
Aurélie Dufour ◽  
France Van Vambeke ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Deep Convection ◽  
Western Mediterranean ◽  
Late Spring ◽  
Small Scale ◽  
Dust Deposition ◽  
Central Mediterranean ◽  
Central Mediterranean Sea ◽  
The Mediterranean ◽  
The Impact

Abstract. We report on the sub-basin variability in particulate organic carbon (POC) remineralization in the western and central Mediterranean Sea in late spring during the PEACETIME (ProcEss studies at the Air–sEa Interface after dust deposition in the MEditerranean sea) cruise. POC remineralization rates were estimated using the excess biogenic particulate barium (Baxs) inventories in the mesopelagic layers (100–1000 m depth) and compared with prokaryotic heterotrophic production (PHP). Baxs-based mesopelagic remineralization rates (MRs) ranged from 25±2 to 306±70 mgCm-2d-1. MRs were larger in the Algero-Provençal (ALG) Basin than in the Tyrrhenian (TYR) and Ionian (ION) basins. Our Baxs inventories and integrated PHP data also indicated that significant mesopelagic remineralization occurred down to 1000 m depth in the ALG Basin in contrast to the ION and TYR basins, where remineralization was mainly located above 500 m depth. We propose that the higher and deeper MRs in the ALG Basin were sustained by an additional particle export event driven by deep convection. The TYR Basin (in contrast to the ALG and ION basins) presented the impact of a previous dust event, as reflected by our particulate Al water column concentrations. The ION and TYR basins showed small-scale heterogeneity in remineralization processes, reflected by our Baxs inventories and integrated PHP data at the Tyrr long-duration station. This heterogeneity was linked to the mosaic of blooming and non-blooming patches reported in this area during the cruise. In contrast to the western Mediterranean Sea (ALG Basin), the central Mediterranean Sea (ION and TYR basins) showed lower remineralization rates restricted to the upper mesopelagic layer during the late spring PEACETIME cruise.

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

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
José C. Báez ◽  
David Macías ◽  
Salvador García-Barcelona ◽  
Raimundo Real
Keyword(s):  
Mediterranean Sea ◽  
Loggerhead Turtle ◽  
Sea Turtle ◽  
Western Mediterranean ◽  
Climatic Conditions ◽  
Fishing Activity ◽  
Leatherback Turtles ◽  
Leatherback Turtle ◽  
Western Mediterranean Sea ◽  
Loggerhead Turtles

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.

scholarly journals Size-dependent survival of European hake juveniles in the Mediterranean Sea

2020 ◽  
Vol 83 (S1) ◽  
pp. 207
Author(s):  
Manuel Hidalgo ◽  
Alessandro Ligas ◽  
José María Bellido ◽  
Isabella Bitetto ◽  
Pierluiggi Carbonara ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Western Mediterranean ◽  
Juvenile Stage ◽  
Ontogenetic Changes ◽  
Size Dependent ◽  
Negative Effect ◽  
The Mediterranean ◽  
The One ◽  
The Impact ◽  
European Hake

Most studies on European hake focus on the recruitment process and nursery areas, whereas the information is comparatively limited on the ecology of the juvenile stage (ca. second year of life)—the one most exploited by the Mediterranean trawl fisheries. Using information of the MEDITS programme, we provide a spatial and temporal assessment of the influence of body size and growth on hake survival from recruits (age 0) to juveniles (age 1), along with the impact of surface temperature and chlorophyll variability. At a biogeographic scale, size-dependent survival is supported, with areas with higher mean length of recruits and juveniles yielding higher survival. A similar pattern was observed at interannual level in some western Mediterranean areas, also mediated by a density-dependent effect on growth. However, the most recurrent inter-annual pattern was a negative effect of size on survival, which could be attributed to potential ontogenetic changes in catchability and underrepresentation of intra-annual recruitment pulses that are seasonally inaccessible to the MEDITS survey. Results also evidence that survival in the Alboran and Adriatic seas is dependent on the primary production variability, and that Corsica and Sardinia could be potential feeding grounds receiving juveniles from neighbouring areas. The present study reveals the importance of size- and growth-dependent survival in the juvenile stage of European hake in the Mediterranean Sea.

scholarly journals Impact of air–sea coupling on the climate change signal over the Iberian Peninsula

2021 ◽  
Author(s):  
Alba de la Vara ◽  
William Cabos ◽  
Dmitry V. Sein ◽  
Claas Teichmann ◽  
Daniela Jacob
Keyword(s):  
Climate Change ◽  
Iberian Peninsula ◽  
Mediterranean Sea ◽  
Large Scale ◽  
Regional Distribution ◽  
Coupled Model ◽  
Climate Change Signal ◽  
The North ◽  
The Mediterranean ◽  
The Impact

AbstractIn this work we use a regional atmosphere–ocean coupled model (RAOCM) and its stand-alone atmospheric component to gain insight into the impact of atmosphere–ocean coupling on the climate change signal over the Iberian Peninsula (IP). The IP climate is influenced by both the Atlantic Ocean and the Mediterranean sea. Complex interactions with the orography take place there and high-resolution models are required to realistically reproduce its current and future climate. We find that under the RCP8.5 scenario, the generalized 2-m air temperature (T2M) increase by the end of the twenty-first century (2070–2099) in the atmospheric-only simulation is tempered by the coupling. The impact of coupling is specially seen in summer, when the warming is stronger. Precipitation shows regionally-dependent changes in winter, whilst a drier climate is found in summer. The coupling generally reduces the magnitude of the changes. Differences in T2M and precipitation between the coupled and uncoupled simulations are caused by changes in the Atlantic large-scale circulation and in the Mediterranean Sea. Additionally, the differences in projected changes of T2M and precipitation with the RAOCM under the RCP8.5 and RCP4.5 scenarios are tackled. Results show that in winter and summer T2M increases less and precipitation changes are of a smaller magnitude with the RCP4.5. Whilst in summer changes present a similar regional distribution in both runs, in winter there are some differences in the NW of the IP due to differences in the North Atlantic circulation. The differences in the climate change signal from the RAOCM and the driving Global Coupled Model show that regionalization has an effect in terms of higher resolution over the land and ocean.

Fish and invertebrate by-catch in the crab pot fishery in the Isle of Man, Irish Sea

2017 ◽  
Vol 98 (8) ◽  
pp. 2099-2111
Author(s):  
Fikret Öndes ◽  
Michel J. Kaiser ◽  
Lee G. Murray
Keyword(s):  
Irish Sea ◽  
Target Species ◽  
Catch Per Unit Effort ◽  
Isle Of Man ◽  
Ecosystem Effects ◽  
By Catch ◽  
Catch Rates ◽  
Taxonomic Groups ◽  
Catch Composition ◽  
Autumn And Winter

Baited trap or pot fisheries are considered to have relatively few wider ecosystem effects on the marine environment, particularly when compared with towed mobile fishing gear. However, this assumption is rarely tested in the field. This study aimed to determine the composition of non-target species that occur in crustacean pots and to assess spatial and temporal differences in catches in the waters around the Isle of Man, Irish Sea. The data were collected using fishery independent surveys and a questionnaire study. Based on fishery independent surveys, a total of five taxonomic groups and 43 species occurred as by-catch. The dominant by-catch species was velvet crab Necora puber. The by-catch per unit effort (BPUE) for all of the non-target species was low particularly in comparison to towed bottom gear fisheries around the Isle of Man. BPUE of species composition varied considerably between different locations around the Isle of Man. The results of both the fishery independent and questionnaire data suggested that the by-catch rates varied with season with peak BPUE occurring in spring which then declined into autumn and winter. By-catch composition did not decrease significantly with an increasing target species catch. Overall, by-catch was low relative to target species catch which may be partially attributable to the use of escape panels in pot fisheries in the Isle of Man.

First record of Sphoeroides spengleri (Osteichthyes: Tetraodontidae) in the Mediterranean Sea

2004 ◽  
Vol 84 (5) ◽  
pp. 1089-1090 ◽  
Author(s):  
J.A. Reina-Hervás ◽  
J.E. García Raso ◽  
M.E. Manjón-Cabeza
Keyword(s):  
Alien Species ◽  
Mediterranean Sea ◽  
First Record ◽  
Western Mediterranean ◽  
Alboran Sea ◽  
Total Length ◽  
The Mediterranean ◽  
Alborán Sea

The capture of a specimen of Sphoeroides spengleri (Osteichthyes: Tetraodontidae), 17 December 2000 and 29·7 mm total length, from the Málaga coast (Alborán Sea, western Mediterranean) represents the first record of a new alien species for Mediterranean waters.

scholarly journals First record of Solea (Microchirus) boscanion (Osteichthyes: Soleidae) in the Mediterranean Sea, with data on other sympatric soleid species

2002 ◽  
Vol 82 (5) ◽  
pp. 907-911 ◽  
Author(s):  
Enric Massutí ◽  
J.A. Reina-Hervás ◽  
Domingo Lloris ◽  
L. Gil de Sola
Keyword(s):  
Climate Change ◽  
Mediterranean Sea ◽  
First Record ◽  
Western Mediterranean ◽  
The Other ◽  
The Mediterranean

The capture of five specimens of Solea (Microchirus) boscanion (Osteichthyes: Soleidae), a species previously unrecorded in the Mediterranean, is reported from the Iberian coast (western Mediterranean). The main morphometric and meristic measurements of this species with data of the other sympatric, and morphologically very similar, soleids Microchirus variegatus and Buglossidium luteum are also given. The record is discussed in relation to climate change and competition between species.

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