Genetic isolation and morphological divergence of Black Sea bottlenose dolphins

The Black Sea is a semi-enclosed body of water that differs from the adjacent Mediterranean Sea in terms of its biodiversity, oceanographical and ecological characteristics. There is growing international concern about pollution in the Black Sea and other anthropogenic threats to its fauna. The bottlenose dolphin (Tursiops truncatus) is one of three species of cetaceans living in the Azov-Black Sea basin. Despite considerable research on bottlenose dolphins elsewhere, the extent of human impacts on the Black Sea populations is unknown. Previous attempts to award special conservation status to Black Sea cetaceans have failed specifically because policy makers have viewed their ecological and evolutionary uniqueness as equivocal. This study assessed divergence between Black Sea, Mediterranean Sea and Atlantic Ocean bottlenose dolphins for 26 cranial measurements (n = 75 adult bottlenose dolphin skulls) and mitochondrial DNA (n = 99 individuals). Black Sea bottlenose dolphins are smaller than those in the Mediterranean, and possess a uniquely shaped skull. As in a previous study, we found the Black Sea population to be genetically distinct, with relatively low levels of mtDNA diversity. Population genetic models suggest that Black Sea bottlenose dolphins have so little gene flow with the Mediterranean due to historical isolation that they should be managed separately.     

Prey depletion caused by overfishing and the decline of marine megafauna in eastern Ionian Sea coastal waters (central Mediterranean)

Surveys primarily aimed at determining dolphin encounter rates were conducted from small inflatable craft in eastern Ionian Sea coastal waters between 1997 and 2004. During 633 surveys totalling 21,276 km of effort, observations of cetaceans and other marine species spotted in a study area of 480 km² were systematically recorded. Common dolphin encounter rates declined 25-fold across the study period, steadily decreasing from 2.18 encounters/100 km in 1997 to 0.09 encounters/100 km in 2004. Encounter rates of tuna also declined significantly. Swordfish encounter rates dropped from 1.03 encounters/100 km in 1997 to 0-0.12 in 1998-2004. Encounter rates of bottlenose dolphins did not show significant trends. The decline of high-order marine predators feeding on epipelagic prey was consistent with the hypothesis of prey depletion, likely resulting from intensive exploitation of local fish stocks, particularly anchovies and sardines. The catholic feeding habits and opportunistic behaviour of bottlenose dolphins may allow them to withstand the effects of overfishing at their present low density.     

Behavioral responses of bottlenose dolphins, Tursiops truncatus, to gillnets and acoustic alarms

Along the east coast of the United States, by-catches of bottlenose dolphins, Tursiops truncatus, in gillnet fisheries exceed removal levels set under the US Marine Mammal Protection Act. One measure proposed to reduce this mortality is the use of acoustic alarms, or pingers, which have proven effective in reducing by-catches of other small cetaceans, but have not been tested with bottlenose dolphins. We examined the responses of bottlenose dolphins to a commercial gillnet equipped with functional (active) and non-functional (control) Dukane NetMark® 1000 alarms near Fort Macon, NC. Between 5 April and 10 May 2001 we used a theodolite to track 59 groups of dolphins around the net. Choice of treatment was random each day and the two shore-based observers were unaware of whether alarms were active (13 days) or controls (9 days). There were no significant differences in the number of groups observed (P=0.315; 1−β=0.835) or in the closest observed approach to the net (P=0.307; 1−β=0.828) between treatments. However, dolphins entered a circular buffer approximately 100 m around the net more frequently with control than active alarms (P=0.015). We conclude that some dolphins responded to the alarms by avoiding the net, but caution that the potential efficacy of alarms is confounded by dolphin behavior. Most dolphins were aware of the net, regardless of the status of alarms, and some dolphins fed on fish in the net or discarded by the fishing vessel. We believe that it would be unwise to use pingers in these fisheries because of the limited behavioral responses we observed in our experiment. Furthermore, the responses we observed are likely to diminish or change over time as dolphins habituate or sensitize to these alarms. Further research is required to understand the behavior responsible for entanglement.     

Status assessment of the Indus River dolphin, Platanista gangetica minor, March-April 2001

A survey was conducted in March and April 2001, to assess the status of the Indus River dolphin, Platanista gangetica minor, throughout its present range. A total of 1535 km of survey effort was conducted, consisting of 1375 km of the Indus River main channel, 136 km of Indus River secondary channels, and 24 km of the Panjnad River, a tributary of the Indus. The effective range of the Indus dolphin has declined by 80% since 1870. The sum of best group size estimates produced an abundance estimate of 965 dolphins. Extrapolation of encounter rates to un-surveyed channels and application of a correction factor to account for missed dolphins indicates that the metapopulation may number approximately 1200 individuals. Dolphins occur in five subpopulations separated by irrigation barrages. A pronounced increase in dolphin abundance and encounter rate was observed in each subsequent downstream subpopulation (except the last). The three largest subpopulations were between Chashma and Taunsa Barrages (84 dolphins; 0.28/km), Taunsa and Guddu Barrages (259 dolphins; 0.74/km) and Guddu and Sukkur Barrages (602 dolphins; 3.60/km). Reasons suggested for the high encounter rate between Guddu and Sukkur Barrages, include high carrying capacity, low levels of anthropogenic threat, effective conservation, and augmentation of the subpopulation by downstream migration of dolphins from upstream.     

Response of travelling bottlenose dolphins (Tursiops aduncus) to experimental approaches by a powerboat in Jervis Bay, New South Wales, Australia

Powerboats are potentially a significant source of disturbance to coastal cetaceans. Information is scarce, however, on the nature of interactions between powerboats and dolphins, particularly when both surface and acoustic behaviour are combined. The surface behaviour and acoustic response of travelling dolphins to approaches by a powerboat were assessed by a series of experimental trials between November 2001 and November 2003 in Jervis Bay, New South Wales, Australia. Dolphin behaviour was monitored continuously from an independent research boat before, during and after a powerboat approached (n = 12). Treatments were interspersed with control observations (n = 12). Changes in surface behaviour indicated differences between the treatment and control periods (z = 2.24, p = 0.025), with dolphins tending to alter their surface behaviour when exposed to the powerboat approach. Analysis also revealed a change in the direction of travel by dolphin groups when approached (z = 3.22, p = 0.001). Changes in surface behaviour occurred at vessel approach distances outside the minimum approach distance of 30 m for recreational and commercial vessels, as proposed by the New South Wales National Parks and Wildlife Service. In contrast, there were no changes in dolphin whistle rates (F_3,12 = 0.74, p = 0.54) or the duration of echolocation click bouts (F_3,12 = 0.76, p = 0.59) when approached. These findings indicate that powerboats do affect the surface behaviour and direction of travelling inshore bottlenose dolphins in Jervis Bay; however it appears that this impact is not reflected in their acoustic behaviour.     

An alternative to dolphin oil as a fish attractant in the Ganges River system: conservation of the Ganges River dolphin

Oil extracted from blubber of the Ganges River dolphin, Platanista gangetica, is used as a fish attractant in India and Bangladesh. This oil fishery is associated with the mortality of hundreds of dolphins every year. Oil from fish scraps was field tested for 121 days during 1997-1999 in the Ganges at Patna and was a very effective alternative to dolphin oil as a fish attractant. Fishing with fish oil resulted in higher catches and greater income per person per hour (Rs. 17.8±12.5) than fishing with dolphin oil (Rs. 11.6±9.3). However, there is no statistically significant difference between the results from fishing with dolphin and fish oil. Oil from fish scraps is inexpensive and can be made readily available to all the fishermen. Its widespread use would help in conserving the endangered Ganges River dolphin.     

Fishery by-catches of marine mammals in Galician waters: results from on-board observations and an interview survey of fishermen

Rates of cetacean by-catch were investigated in Galician waters (NW Spain) using a combination of observer trips on fishing vessels, a carcase recovery scheme and an interview survey of fishermen, carried out over two years (1998-1999). All these data sources are suspected of underestimating by-catch due to the sample of co-operating fishermen being, necessarily, self-selecting. No by-catches were seen during observer trips, although not all sectors of the fishery could be covered. The carcass recovery scheme yielded seventeen cetacean carcases over two years, which compares to around 35 by-caught cetaceans recorded annually by the Galician strandings network. Analysis of interview data suggested that around 200 cetaceans might be caught annually in inshore waters and around 1500 in offshore waters. Confidence limits were wide for all estimates. The highest by-catch rates were estimated for gillnets and offshore trawling. The majority of by-catches are small dolphins, probably mainly Delphinus delphis. Smaller numbers of Tursiops truncatus and Globicephala melas are also reported. Comparing the interview estimates of by-catch rates with minimum estimates of population size, it is suggested that by-catches of D. delphis and T. truncatus may be unsustainably high and that routine monitoring of fishery by-catches in Galician fisheries is required.     

Do fences create an edge-effect on the movement patterns of a highly mobile mega-herbivore?

Physical barriers, such as rivers and roads, constrain the movement of animals, usually by preventing access to adjacent habitats and impeding dispersal. Fences are artificial barriers that are commonly used as a conservation tool to intentionally restrict movements of animals to within protected reserves. However, the potential edge-effect of fences on the behaviour of animals within reserves is poorly understood. We examined the effect of fences on the movement patterns of African elephant (Loxodonta africana), an ecosystem modifier, in Pilanesberg National Park, South Africa. We used linear and non-linear models to determine the relationship between minimum distance from fence and seasonal daily net displacement of six GPS-collared female elephant. Elephant movement patterns were best explained by a piecewise regression that showed a strong negative relationship between minimum distance from fence and daily net displacement up to a “breakpoint” distance of 2551 m in the dry season and 3829 m in the wet season. The effect of the fence dissipated beyond this distance in both seasons. The increased tortuosity in movement patterns of elephant in the central area of the reserve suggested that they used this area more intensively for foraging compared to the peripheral area, as confirmed by differences in habitat selection. This occurs despite there being no difference in habitat composition between these areas. The decreased use of areas near the fence and more intensive foraging in the central areas constitute an important edge-effect of fences. Since elephant are ecosystem engineers, such edge-effects could potentially cascade throughout the reserve, adversely altering ecologically processes, particularly in reserves with a high edge-to-area ratio.     

Small cetacean captures in Peruvian artisanal fisheries: High despite protective legislation

We detail the first direct, at sea monitoring of small cetacean interactions with Peruvian artisanal drift gillnet and longline fisheries. A total of 253 small cetaceans were captured during 66 monitored fishing trips (Gillnet: 46 trips; Longline: 20 trips) from the port of Salaverry, northern Peru (8^o14′S, 78^o59′W) from March 2005 to July 2007. The most commonly captured species were common dolphins (Delphinus spp.) (47%), dusky dolphins (Lagenorhynchus obscurus) (29%), common bottlenose dolphins (Tursiops truncatus) (13%) and Burmeister’s porpoises (Phocoena spinipinnis) (6%). An estimated 95% of common dolphin bycatch was of long-beaked common dolphins (Delphinus capensis). Overall bycatch per unit effort for gillnet vessels (mean ± sd) was estimated to be 0.65 ± 0.41 animals.set⁻¹ (range 0.05-1.50) and overall catch (bycatch and harpoon) was 4.96 ± 3.33 animals.trip⁻¹ (range 0.33-13.33). Based upon total fishing effort for Salaverry we estimated the total annual average small cetacean bycatch by gillnet vessels as 2412 animals.year⁻¹ (95% CI 1092-4303) for 2002-2007. This work indicates that, in at least one Peruvian port, bycatch and harpooning of small cetaceans persist at high levels and on a regular basis, particularly in driftnet vessels, despite the existence since the mid-1990s of national legislation banning the capture of marine mammals and commerce in their products. It is concluded that the coast of Peru is likely still one of the world’s principal areas for concern regarding high small cetacean bycatch and there is clearly an urgent need to increase the geographic scope of observer effort to elucidate the full magnitude of this issue.     

Climate change and the cetacean community of north-west Scotland

1. Climate change is thought to affect the composition and structure of local ecological communities. We investigate whether ocean warming around north-west Scotland since 1981 has been associated with changes in the local cetacean community.2. Analysis of strandings from 1948 to 2003 found that no new species per decade were recorded in north-west Scotland between 1965 and 1981. This rose to 2.0 new species per decade from 1988 onwards. The new species recorded since 1988 are generally restricted to warmer waters, while those recorded prior to 1981 regularly occur in colder waters.3. In the period 1992 to 2003, the relative frequency of stranding of white-beaked dolphin, a colder water species, has declined while strandings of common dolphin, a warmer water species, have increased. Similarly, sightings surveys conducted in May-September 2002 and 2003 show that the relative occurrence and abundance of white-beaked dolphins have declined and common dolphins increased in comparison to previous studies.4. These observations are consistent with changes in the local cetacean community being driven by increases in local water temperature. If such temperature changes continue, some formerly abundant cold-water species, such as white-beaked dolphins, may be lost from this cetacean community. In a wider context, such changes may lead to populations of cetaceans moving out of areas specifically designated for their protection as they respond to changes in local oceanic conditions.     

Driftnet fishing and biodiversity conservation: the case study of the large-scale Moroccan driftnet fleet operating in the Alboran Sea (SW Mediterranean)

Illegal, large-scale driftnets are still used in several Mediterranean areas. According to international official sources, Morocco harbors the bulk of this fleet in the Mediterranean. To ascertain its biodiversity impact, 369 fishing operations (worth 4140 km of driftnets set) made by the driftnet fleet targeting swordfish (Xiphias gladius) based in Al Hoceima (Alboran Sea) were monitored between December 2002 and September 2003. Parallel surveys were made in the main Mediterranean ports and in that of Tangiers, in the Gibraltar Straits, to estimate the total fishing effort. Results showed an active driftnet fleet conservatively estimated at 177 units. Estimated average net length ranges from 6.5 to 7.1 km, depending on the port, though actual figures are suspected to be much higher (12-14 km). Most boats perform driftnet fishing all year round, resulting in very high annual effort levels. A total of 237 dolphins (short-beaked common dolphin, Delphinus delphis, and striped dolphin, Stenella coeruleoalba), 498 blue sharks (Prionace glauca), 542 shortfin makos (Isurus oxyrinchus) and 464 thresher sharks (Alopias vulpinus) were killed by the boats monitored during the sampling period, during the peak of the swordfish fishery, along with 2990 swordfish. Loggerhead turtle (Caretta caretta) was also caught (46 individuals). Estimates for a 12-month period by the whole driftnet fleet yielded 3110-4184 dolphins (both species) and 20,262-25,610 pelagic sharks distributed in roughly equal proportions for P. glauca, I. oxyrinchus and A. vulpinus, in the Alboran Sea alone; further 11,589-15,127 dolphins and 62,393-92,601 sharks would be killed annually around the Straits of Gibraltar. Dolphins suffer from annual take rates exceeding 10% of their population sizes in the Alboran Sea; this unsustainable impact is particularly worrying for D. delphis, because its last remnant healthy population in the Mediterranean occurs in this area. Average catch rate for swordfish, the main target species, amounted to only 0.8 individuals/km net set. Pelagic sharks are actively targeted by a part of the fleet.     

Measurement, management and mitigation of operational interactions between the South Australian Sardine Fishery and short-beaked common dolphins (Delphinus delphis)

This study arose from recommendations given in response to a legislated ecological assessment of the South Australian Sardine Fishery in 2004, urging it to: (i) attempt to mitigate operational interactions with marine mammals if excessive levels were detected; and (ii) improve the accuracy of their reporting of these events.An initial observer program revealed high rates of encirclement and mortality (1.78 and 0.39 dolphins per net-set, respectively) of short-beaked common dolphins (Delphinus delphis). This equated to an estimate of 1728 encirclements and 377 mortalities across the entire fleet over the same period. The average time taken for fishers to respond to encirclements was 135.93 ± 3.72 min and 21.3% of encircled animals subsequently died. During that time, fishers only reported 3.6% of encirclements and 1.9% of mortalities recorded by observers.A code of practice (CoP) was subsequently introduced aimed at mitigating operational interactions. A second observer program revealed a significant reductions in the observed rates of dolphin encirclement (0.22; down 87.3%) and mortality (0.01; down 97.1%) with an estimate of 169 and eight, respectively. The average time taken for fishers to respond to dolphin encirclements also reduced to 16.33 ± 4.67 min (down 76.9%) and the proportion of encircled animals that subsequently died reduced to 5.0%. Agreement between industry reports and observer records improved, with the fishery reporting 57.9% and 58.9% of the rate of encirclements and mortalities, respectively, recorded by observers.A number of avoidance and release strategies in the CoP may have been responsible for these improvements. In particular, fishers were required to delay or relocate their activities if dolphins were observed prior to fishing and to release encircled dolphins immediately or abort the fishing event if release procedures were unsuccessful. Future improvements to the CoP include: (i) improved response times when an encircled dolphin is detected; (ii) better use of behavioural cues for deciding when to abort a net-set; (iii) ceasing fishing during rough weather; and (iv) continuing to increase reporting accuracy by fishers. It is also recommended that the abundance, movements and boundaries of the common dolphin population in the region be determined, so that the impact of fishing activities on their status can be established.     

Site fidelity and along-shore range in Hector's dolphin, an endangered marine dolphin from New Zealand

To document site fidelity and the alongshore range of individual Hector's dolphins we analysed sightings of 32 photographically identified dolphins, each seen ?10 times at Banks Peninsula, New Zealand, between 1985 and 1997. The furthest two sightings of an individual were 106 km apart. All other individuals ranged over less than 60 km (x?=31.0 km, SE=2.43) of coastline. Gender did not significantly influence alongshore range (female x?=30.4 km, SE =3.21, n=18; male x?=27.4 km, SE=5.68, n=5). Site fidelity was high: for example, on average, individuals were seen in Akaroa Harbour for about two thirds of the years they were known to be alive. These data suggest that impacts on Hector's dolphins are most appropriately managed on a small spatial scale.     

From common to rare: The case of the Mediterranean common dolphin

Although overfishing has been recognized as responsible for the decline of major fish stocks, it has been less easy to demonstrate its indirect and detrimental effects on marine mammals, particularly dolphins. Competition with fisheries for the same food resources has been hypothesized to have led to the decline of several species of dolphins, including the endangered Mediterranean short-beaked common dolphin. Based on an ecosystem model for the Inner Ionian Sea Archipelago, a former hotspot for common dolphins in the Mediterranean Sea, we investigated the effect of increasing fishing effort on common dolphins, its prey and on marine biodiversity and we evaluated the outcomes of different fisheries closures (1 – closure of the purse seine fishery, 2 – closure of purse seine, trawl and beach seine fisheries, 3 – entire area closed to fisheries) ran between the years 2011 and 2030. Our results showed that local fisheries have negatively impacted the marine biodiversity of the ecosystem causing sharp declines of common dolphins and major fish stocks and weakening the robustness of the marine food web. The implementation of fisheries closures would gradually recover fish stocks, while common dolphins would increase more pronouncedly only if the study area was to be closed to all fisheries. As shown in this study, common dolphins have reflected ecosystem changes and degradation over time. Ensuring the survival of dolphin populations is thereby essential to enhance marine ecosystems and ensure sustainable fishing.     

Catch composition and conservation management of a human-dolphin cooperative cast-net fishery in the Ayeyarwady River, Myanmar

A study of the catch composition of a cooperative fishery practiced between cast-net fishermen and Irrawaddy dolphins (Orcaella brevirostris) in the Ayeyarwady River, Myanmar, was conducted at fishing grounds near Myay Zun, Indown, The‘ Kyun and Hsithe during November and December 2006 and 2007. A total of 4139 fish from 42 species and five crustaceans from a single species were recorded in 1099 net casts made during 33 fishing sessions. Sufficient data were only available to conduct in-depth analyses of catches obtained from Myay Zun (776 net casts, 41.2% while cooperating with dolphins). These analyses indicated that catch per cast, defined by the number of fish, their weight and economic value, was higher (Mann-Whitney P < 0.001) during both 2006 (about double for all parameters) and 2007 (about triple for all parameters) while the dolphins were cooperating with fishermen. Differences in catch between cooperative and non-cooperative net casts were primarily explained by the much higher frequency of empty catches (Chi-square P < 0.001, df = 3 during both 2006 and 2007) recorded during non-cooperative casts (68.3% and 71.3% in 2006 and 2007, respectively) versus cooperative casts (13.7% and 31.6% in 2006 and 2007, respectively). Overall, fish catch could be described as meager, which may partially be explained by the abnormal timing of flow recession during both years. However, the cast-net fishermen also consistently reported dramatically depleted catches in recent years due to illegal electric fishing. Elimination of electric fishing in a recently established protected area will be crucial for conserving the dolphins and the cooperative cast-net fishery.     

Population sizes, site fidelity and residence patterns of Australian snubfin and Indo-Pacific humpback dolphins: Implications for conservation

Very little is known about the ecology of snubfin Orcaella heinsohni and Indo-Pacific humpback dolphins Sousa chinensis in Australian waters. We used photo-identification data collected between 1999 and 2002 in Cleveland Bay, northeast Queensland, to estimate abundance, site fidelity and residence patterns of these species in order to make recommendations for their effective conservation and management. Our abundance estimates indicate that less than a hundred individuals of each species inhabit this coastal area. Even with relatively unbiased and precise abundance estimates population trends will be extremely difficult to detect in less than three years unless changes in population size are very high (>20% p.a.). Though both species are not permanent residents in Cleveland Bay, they both used the area regularly from year to year following a model of emigration and reimmigration. Individuals of both species spend periods of days to a month or more in coastal waters of Cleveland Bay before leaving, and periods of over a month outside the study area before entering the bay again. Because of their small population sizes and movement patterns, snubfin and humpback dolphins are particularly vulnerable to local extinction. Our results illustrate that: (1) detection of population trends should not be a necessary criterion for enacting conservation measures of both species in this region, and (2) efforts to maintain viable populations of both species in Cleveland Bay must include management strategies that integrate anthropogenic activities in surrounding areas.     

Experimental assessment of oyster transfers as a vector for macroalgal introductions

Introduction of non-indigenous species can alter marine communities and ecosystems. In shellfish farming, transfer of livestock, especially oysters, is a common practice and potentially constitutes a pathway for non-indigenous introductions. Many species of seaweeds are believed to have been accidentally introduced in association with these transfers, but there is little direct evidence.We experimentally simulated the transfer of oysters from the Thau Lagoon (France). These transfers involved increasing periods of aerial emersion and additional brine and hot water treatments. The brine and hot water treatments were evaluated as a means of reducing the probability of algal introductions with oyster transfers. Shells were cultured for 40 days in experimental tanks to identify the macroalgae likely to be introduced with any oyster transfer.A total of 57 macroalgal taxa, including 16 taxa not indigenous to the Thau Lagoon, were recorded across all treatments and experiments. The abundance of some species increased in several cases following aerial emersion. Elimination treatments (immersion in brine or hot water) significantly reduced algal diversity, with hot water treatments resulting in no species or only tubular Ulva spp. present.The results support the hypothesis that oyster transfers are effective as primary and secondary vectors of macroalgal introductions. Relatively simple changes to the transfer practice (particularly hot water treatments) are suggested as a means of reducing the risk of non-indigenous algal introductions.     

牡蛎壳作生物滞留填料对城市地表径流污染物去除效果研究

选择磷吸附性能最强的牡蛎壳作为填料,在实验室构建3个生物滞留模拟装置(A柱:养殖牡蛎壳;B柱:海滩牡蛎壳;C柱:养殖牡蛎壳存在淹没区),采用道路径流模拟配水作为进水,研究牡蛎壳作为填料对青岛市城市径流常见污染物氮磷及COD的处理效果,并对各污染物去除机理进行探讨。结果表明:3种牡蛎壳填料的生物滞留设施对总磷的去除效果最好,在进水磷浓度为0.57～1.83 mg/L条件下,无淹没区装置平均去除率为96.12%,存在淹没区的装置平均去除率为91.02%。养殖牡蛎壳与海滩牡蛎壳对磷的去除效果并无明显差异,淹没区不利于磷的去除。在前期进水过程中(前5次进水)3个模拟装置氨氮(NH_4~+)的出水浓度高于进水浓度,延长落干期后,装置的NH_4~+去除率均上升,B柱NH_4~+平均去除率(58.83%)相对于A柱(48.77%)及C柱(53.06%)更高,有无淹没区对NH_4~+去除并无明显影响。由于填料中有机物的渗沥,首次进水出现严重COD淋出,在随后的进水过程中,COD去除效果迅速上升并稳定,3个模拟柱去除率分别为50.34%,23.47%和47.75%。由于反硝化作用受阻,对硝氮(NO_3~-)的去除效果不佳。整体看来,养殖牡蛎壳可以应用于青岛市生物滞留设施的填料,为加强滞留设施NO_3~-的去除效果,还需要采用强化脱氮措施。     

Pelagic longlines: A threat to sea turtles in the Equatorial Eastern Atlantic

Pelagic longlines are widely known to interact with several species of sea turtles, and there is an increasing concern about the by-catch of turtles in commercial fisheries and its impact on their populations. However, information on sea turtle by-catch in the South Atlantic Ocean is scarce, and there are no quantitative by-catch data available on olive ridleys for the Equatorial Eastern Atlantic. In this paper we analyze data collected by observers on board an Uruguayan long-liner targeting swordfish in two areas in the Equatorial Eastern Atlantic: off the Gulf of Guinea and north of Saint Helenaa Island. Specimens of Lepidochelys olivacea and Dermochelys coriacea were hooked or entangled in 26 longline sets. All registered interactions with olive ridleys took place off the The Gulf of Guinea, with captures ranging from 1 to 3 specimens in a single set. The captured specimens, though not measured directly, appeared to be juveniles. In addition, the examination of the stomach contents of one female mako shark showed dermal scutes, vertebrae and the complete head of a sea turtle identified as L. olivacea, allowing us to estimate its curved carapace length. In contrast, adult specimens of D. coriacea were caught in the two fishing areas. The capture of 10 individuals in a single set was recorded. Due to the high rate of sea turtle by-catch observed off the The Gulf of Guinea (1.02 ind/1000 hooks) conservation programs in the area should take into consideration the possible existence of a developmental and feeding area in this zone. Accordingly, longline fisheries in this area should be monitored and mitigation measures put in place to avoid or minimize damage to the pelagic phase of African populations of sea turtles.     

The western jewel butterfly (Hypochrysops halyaetus): factors affecting adult butterfly distribution within native Banksia bushland in an urban setting

Adult western jewel butterflies Hypochrysops halyaetus Hewitson were studied in the Koondoola Regional Bushland Reserve on the northern outskirts of the Perth metropolitan area, Australia, in 1999. The butterfly is myrmecophilous, and the southern (Perth) form is considered to be ‘Vulnerable’. Butterfly dispersal, distribution, population size and habitat preferences were estimated using mark-recapture techniques. Butterflies were capable of moving large distances, and were widespread within the reserve but with a low density; however, one small physical area (80 × 20 m) contained a colony with large numbers of individuals. This colony, and an adjacent area of bush, was subject to a detailed microdistribution study: 1158 butterflies were marked within it over a 25-day period. The small size of the microdistribution study area compromised statistical independence assumptions: spatial autocorrelation was tested for and corrected, where appropriate, using a Markov-chain Monte-Carlo approach. Sex differences were evident in spatial autocorrelation: female data were not spatially autocorrelated, whilst male data was. The latter probably reflects the impact of the perching mode of mate location employed by males. Butterflies appeared to prefer rather degraded bush typical of a post fire/disturbance regime with high densities of the host plant Jacksonia sternbergiana. Males were positively correlated with the proportion of bare ground, again probably relating to preferred perching sites for mate location. Females were negatively correlated with Conospremum stoechadis probably indicating dense ground cover in degraded areas and Xanthorrhoea preissii probably an indicator at the site of more mature vegetation. Reserve management to improve vegetation quality may threaten the persistence of the butterfly within the reserve, whilst controlled burning to create even quite small new areas of habitat in an urban situation may be difficult to achieve. The creation of suitable habitat may be possible using mechanical means, provided the action of fire is not an essential component of habitat creation. As the western jewel appears to prefer degraded vegetation, it is possible that there may be opportunities for this species’ expansion within the urban environment provided that its mutualistic ant partner is also present.