Atlantic Blue Marlin, Makaira nigricans, and White Marlin, Tetrapterus albidus, Bycatch of the Japanese Pelagic Longline Fishery, 1960–2000

ABSTRACT—Since the late 1950’s, a multi-national longline fishery has operated throughout the Atlantic Ocean to supply the growing global demand for tunas (Scombridae) and swordfish, Xiphias gladius. Two species caught as bycatch include Atlantic blue marlin, Makaira nigricans, and white marlin, Tetrapterus albidus, referred to in this paper as “Atlantic marlin.” Pelagic longlining has consistently been the principal source of adult mortality for both species, which are currently depleted and have been so for more than two decades. In this paper, we examined aspects of the Atlantic marlin bycatch of the Japanese pelagic longline fishery from 1960 to 2000. Temporal and spatial patterns in effort, target catch (species combined), marlin bycatch, marlin catch-per-unit-effort (nominal CPUE), and ratios of marlin bycatch to target catch (B: T ratios) were analyzed. An objective was to reveal changes, if any, in marlin bycatch associated with the fishery’s target species “switch” (ca. 1980–87) from mostly surface-associated tunas to mostly the deeper-dwelling bigeye tuna, Thunnus obesus. The highest values of all variables examined occurred during the 1960’s and then fell by the second half of that decade. Since 1970, mean levels of fishing effort, target fish catches, and blue marlin landings have increased significantly, while blue marlin CPUE and B:T ratios have remained relatively stable. Concurrently, white marlin landings, CPUE, and B:T ratios have all declined. While results suggest the fishery’s target species change may have been a factor in lowering white marlin bycatch, the same cannot be said for blue marlin. Relative increases in blue marlin B:T ratios off the northeastern coast of South America and in the wider eastern Atlantic are cause for concern, as are continuing trends of CPUE decline for white marlin in this data set as well as others.

Blue Marlin, Makaira nigricans, Movements in the Western North Atlantic Ocean: Results of a Cooperative Game Fish Tagging Program, 1954-88

Blue marlin, Makaira nigricans, tag and recapture data are summarized for 1954-1988. During this period, 8,447 fish have been tagged and only 30 (0.35 percent) have been returned. Results of the tagging program indicate that blue marlin not only travel considerable distances (7,OOO km from the U. S. Virgin Islands to the Ivory Coast of West Africa), but have remained at large for up to 8 years. Seasonal movements, however, are difficult to determine accurately.

A rapid PCR-based assay for identification of cryptic Myotis spp (Myotis mystacinus, Myotis brandtii and Myotis alcathoe).

The development of a quick PCR-based method to distinguish European cryptic Myotis spp., Myotis mystacinus, Myotis brandtii and Myotis alcathoe is described. Primers were designed around species-specific single nucleotide polymorphisms (SNP’s) in the ND1 mitochondrial gene, and a pair of control primers was designed in the 12S mitochondrial gene. A multiplex of seven primer combinations produces clear species-specific bands using gel electrophoresis. Robustness of the method was tested on 33 M. mystacinus, 16 M. brandtii and 15 M. alcathoe samples from across the European range of these species. The method worked well on faecal samples collected from maternity roosts of M. mystacinus. The test is intended to aid collection of data on these species through a rapid and easy identification method with the ability to use DNA obtained from a range of sources including faecal matter.

The status of the cryptic bat species, Myotis mystacinus and Myotis brandtii in Ireland

The recent identification of Myotis brandtii in Ireland raised the possibility that many roosts previously identified as M. mystacinus had the potential of being misidentified M. brandtii. Thus, the distribution and population estimates for M. mystacinus may have been over-estimated, while M. brandtii may have been under-estimated. Results from an all Ireland genetic survey of known M. mystacinus maternity roosts confirm that no long term misidentification has taken place. All specimens caught and sampled were M. mystacinus. Additonally, no further records of M. brandtii were found during six nights of woodland trapping using the acoustic lure. While the status of M. mystacinus in Ireland is now listed as ‘least concern’ in the Irish Red List, M. brandtii is listed as ‘data deficient’ and cannot currently be considered a resident species

The spatial ecology of the whiskered bat (Myotis mystacinus) at the western extreme of its range provides evidence of regional adaptation

Although widespread, the ecology of the whiskered bat, Myotis mystacinus in Europe remains poorly understood. Ireland is positioned at the most western extreme of this species' range. To ascertain the ecology of M. mystacinus at its geographic range extreme, the roosting behaviour, home range and habitat use of females in a maternity roost in Ireland was investigated by radio-tracking. M. mystacinus were active in a diversity of habitats: namely, mixed woodland, riparian vegetation, arable land and rough grassland. However, only mixed woodland and riparian habitats were selected as core foraging areas. This is in contrast to a previous study from Britain where only pasture was utilised but is in agreement with data from Slovakia, where woodland was also selected, whilst riparian areas were also utilised by this species in Germany. A high degree of overlap in the foraging areas of individuals was observed. A total of seven roosts were utilised by tracked bats and roost switching behaviour was observed. We discuss our contrasting results in respect to range limitations, regional variability in landscape structure and the composition of bat communities. The present results have implications for the conservation of M. mystacinus within Ireland and other parts of its range, highlighting the need for range wide ecological studies. Regional variability in the ecology of bats related to landscape factors is an important consideration for bat conservation and therefore must be incorporated into future management plans. (C) 2012 Deutsche Gesellschaft fur Saugetierkunde. Published by Elsevier GmbH. All rights reserved.

A rapid PCR-based assay for identification of cryptic Myotis spp. (M. mystacinus, M. brandtii and M. alcathoe)

The development of a quick PCR-based method to distinguish European cryptic Myotis spp., Myotis mystacinus, Myotis brandtii and Myotis alcathoe is described. Primers were designed around species-specific single nucleotide polymorphisms (SNP's) in the ND1 mitochondrial gene, and a pair of control primers was designed in the 12S mitochondrial gene. A multiplex of seven primer combinations produces clear species-specific bands using gel electrophoresis. Robustness of the method was tested on 33 M. mystacinus, 16 M. brandtii and 15 M. alcathoe samples from across the European range of these species. The method worked well on faecal samples collected from maternity roosts of M. mystacinus. The test is intended to aid collection of data on these species through a rapid and easy identification method with the ability to use DNA obtained from a range of sources including faecal matter.

Isolation and characterization of eight polymorphic microsatellite loci for Natterer's bat, Myotis nattereri (Vespertilionidae, Chiroptera)

Eight new microsatellite loci were isolated and characterized for the Natterer's bat Myotis nattereri from a microsatellite-enriched genomic library. The usefulness of these markers was assessed by screening a sample comprising 100 specimens collected from throughout the species range in Europe. Both moderately and highly polymorphic loci were identified with 3-17 alleles segregating per locus (mean 8.1 SE +/- A 0.048). No evidence for departure from HWE or linkage disequilibrium among loci was observed. These markers will provide a valuable addition to the molecular toolbox currently available for studies of population genetic structure, parentage and social organisation of M. nattereri and related species.

Epidemiological traits of the malaria-like parasite Polychromophilus murinus in the Daubenton¿s bat Myotis daubentonii.

BackgroundThe great diversity of bat haemosporidians is being uncovered with the help of molecular tools. Yet most of these studies provide only snapshots in time of the parasites discovered. Polychromophilus murinus, a malaria-like blood parasite, specialised on temperate-zone bats is a species that is being `rediscovered¿. This study describes the infection dynamics over time and between host sex and age classes.MethodsFor three years we followed the members of three breeding colonies of Myotis daubentonii in Western Switzerland and screened them for the prevalence and parasitemia of P. murinus using both molecular tools and traditional microscopy. In order to identify more susceptible classes of hosts, we measured, sexed and aged all individuals. During one year, we additionally measured body temperature and haematocrit values.ResultsJuvenile bats demonstrated much higher parasitemia than any other age class sampled, suggesting that first exposure to the parasite is very early in life during which infections are also at their most intense. Moreover, in subadults there was a clear negative correlation between body condition and intensity of infection, whereas a weak positive correlation was observed in adults. Neither body temperature, nor haematocrit, two proxies used for pathology, could be linked to intensities of infection.ConclusionIf both weaker condition and younger age are associated with higher infection intensity, then the highest selection pressure exerted by P. murinus should be at the juvenile stage. Confusion over the identities and nomenclature of malarial-like parasites requires that molecular barcodes are coupled to accurate morphological descriptions.