Search

Bycatch in static nets (i.e., gillnets, trammel nets and tangle nets) has been identified as the leading cause of harbour porpoise mortality globally. Various options are available for mitigating and managing this risk. However, selecting the most effective management measures to balance harbour porpoise conservation needs with sustainable fishing practice is challenging. By understanding the spatial variation of bycatch risk, it is possible to tailor mitigation and management options for a specific localised area or region. This study identified areas of potential interaction between harbour porpoise and static net fishing activity. An interaction index, a measure of the coincidence of porpoise and fishing activity, was developed. Using this approach, it was possible to differentiate between areas that potentially represented concentrations of higher bycatch risk and other areas with a lower but more widespread level of risk. For the Irish and Celtic Seas, an area recognised as having the highest harbour porpoise bycatch rate in European waters, there was a low to moderate interaction index, with the risk spread over a relatively large area. In the North Sea, in contrast, high values of the interaction index occurred in smaller areas, indicating that bycatch risk was more concentrated in this region. With the exception of some coastal areas, the interaction index was generally low for the West of Scotland and Ireland region. The identification of potential areas of interaction between harbour porpoise and static net fishing provides an opportunity to focus monitoring efforts and inform management decisions. For example, the use of area‐based management encompassing small areas may be appropriate when spatially concentrated risk of bycatch is evidenced, whereas the use of technical measures, such as pingers, could be considered for areas with widespread lower risk of bycatch. [ABSTRACT FROM AUTHOR]

Limpets play an important role in structuring the intertidal fringe, one of the most heavily impacted marine habitats. A large number of limpet species are listed as Endangered or Vulnerable, including Patella ferruginea, one of the most endangered marine invertebrates in the Mediterranean Sea.Relocation attempts have been made as a conservation tool for reintroductions and population reinforcements for P. ferruginea. Some relocations were mandatory because of port infrastructure repairs in areas where viable populations of this limpet occurred. However, most relocations attempted to date have experienced high mortality rates, leading to the Spanish National Conservation Strategy not recommending this approach for this species.In this study, 84 individuals of P. ferruginea were relocated, using artificial portable plates (APPs) installed on the ripraps of the Port of Ceuta (Western Mediterranean Sea). These plates were divided into two groups and relocated: (i) as a translocation to a nearby site with similar environmental conditions to the donor area (procedural control); and (ii) as a reinforcement translocation to a relatively distant location (30 km, Algeciras Bay) (experimental procedure). The mortality of the translocated individuals in the procedural control after 10 weeks was similar (6.6%) to that expected for natural populations, whereas the mortality rate for individuals in the reinforcement translocation was higher (26.6%).The APPs have been proven to be a feasible method for translocation, as they result in relatively low mortality by preventing the stress and damage caused by limpet detachment from substrata. The constraints caused by reinforcement translocation to a new environment seem to be the cause of the increased mortality, as the translocated limpets changed their home scar at a much higher rate than the control limpets did. [ABSTRACT FROM AUTHOR]

The UK is committed to reducing or eliminating the by‐catch of protected species in fisheries. Of key concern is the by‐catch of harbour porpoise in static nets. Fishers do not want to catch harbour porpoise, and the only proven effective mitigation measure currently available is an acoustic device known as a 'pinger'.Legislative requirements for the mandatory use of pingers on larger vessels (i.e. those greater than 12 m in length) has resulted in a by‐catch reduction of approximately 17% for the UK fleet annually. In most areas where the risk of by‐catch is high (i.e. the southern North Sea, English Channel, and Bristol Channel), smaller inshore vessels (i.e. less than 12 m in length) account for over 90% of the fishing effort (determined as days at sea).Small inshore vessels are not permitted to use pingers without a licence. The information required for a licence, however, makes it extremely difficult for fishers to obtain one. Without access to effective mitigation in most of the static net fleet, it seems unlikely that the UK will meet its ambition to minimize or eliminate harbour porpoise by‐catch.Finding workable and effective solutions for smaller vessels is essential. As harbour porpoise by‐catch is such a rare event, it is unlikely that the mandatory use of pingers on all static net vessels will be cost‐effective. Nor is such widespread deployment considered desirable because of the potential consequences on the conservation status of harbour porpoise. A potential solution within the current UK legislative framework is proposed that would facilitate the use of pingers in small‐scale localized fisheries with a high risk of by‐catch until a suitable mitigation alternative to pingers becomes available. [ABSTRACT FROM AUTHOR]

Archived logbooks detailing landings at Scottish shore‐based whaling stations between 1903 and 1951 were used to map whale catch locations. Historical distribution and occurrence are inferred and summary statistics on total landings are updated for blue (Balaenoptera musculus), fin (Balaenoptera physalus), humpback (Megaptera novaeangliae), North Atlantic right (Eubalaena glacialis), sei (Balaenoptera borealis) and sperm (Physeter macrocephalus) whales: a total of 9,996 whales were caught during this period, which is 3.7% higher than previously reported and 25% higher for blue whales.The most frequently caught species were fin and sei whales. Whaling off Scotland in the 1920s contributed to the likely extinction of right whales in the eastern North Atlantic. Blue whales, once regularly hunted to the west of Scotland, are now rarely documented there and North‐east Atlantic whaling appears to have had a significant and lasting impact on sei whales.Analysis of whaling effort indicates that catch rates remained high despite the depletion of some species. This, may be a consequence of two features of Scottish shore‐based whaling: (1) the mixed species catch composition; and (2) the catching of whales as they migrated through Scottish waters.The findings of this study highlight the historical significance of the shelf‐seas around Scotland as a habitat for some species, which was not apparent from previous studies. These results can inform where there may be potential for the recovery of some species in the future.Current major threats in the North Atlantic include entanglement, ship strike and displacement owing to the effects of climate change. The baseline and historical information on distribution and seasonal occurrence examined here is important for informing spatial and temporal measures to reduce these threats. If populations are to recover post‐whaling there is an increasing need to reduce threats such as ship strikes and entanglement, whose magnitude is proportional to whale density. [ABSTRACT FROM AUTHOR]

The Barataria Bay Estuarine System (BBES) Stock of common bottlenose dolphins (Tursiops truncatus) in the northern Gulf of Mexico has been a focus of extensive research as a result of the Barataria Basin, Louisiana being one of the most heavily oiled estuaries following the Deepwater Horizon oil spill. The goal of this study was to build upon previous research to better understand social and genetic structure of BBES dolphins.Photo‐identification data from 2010–2019 were analysed with SOCPROG to identify dolphin social clusters. Genetic analyses were conducted on samples obtained during remote biopsy surveys and health assessments (2010–2018) to assess if identified social clusters were congruent with genetic clustering results, and to evaluate relatedness and gene flow within and between social and genetic clusters. Spatial analyses of the cumulative photo‐identification sighting histories from each cluster were also used to determine their geographic range and degree of overlap within the Barataria Basin.Social analyses identified four distinct clusters with some degree of geographic overlap and similar utilization distributions as the three identified genetic clusters. Dolphins in the Barataria Basin were confirmed to be genetically differentiated from those in adjacent coastal waters.In general, genetic analyses differentiate distinct dolphin communities established through long‐term (generational) preferential breeding behaviour. In contrast, social associations can be more fluid over the short‐term, may change in response to habitat or predator/prey changes, and strong associations can be formed between a mix of related and unrelated individuals. The combination of genetic and social methodologies is valuable for developing a better understanding of complex dolphin social interactions and provides unique insights into dolphin behaviour that can be important for developing effective management strategies. [ABSTRACT FROM AUTHOR]

Seal populations in the Gulf of Maine have been recovering from historical bounty‐driven declines since they received federal protection in 1972. In the past few decades, their population growth has sparked renewed concerns over conflict between pinniped and fish conservation.In the Penobscot River in Maine, USA, where restoration efforts over the past decade have aimed at restoring diadromous fish runs, seal predation on the endangered Atlantic salmon (Salmo salar) has become a growing concern.Quantitative and qualitative data for individual salmon, as well as the presence of putative seal‐induced injury, have been collected from salmon passing upriver at dams in the Penobscot River since 2012.An analysis of seal‐induced injury rate with demographic data, river herring returns, estuary fish biomass estimates, and timing of peak estuary fish biomass revealed that the seal‐induced injury rate declined in the Penobscot River from 2012 to 2019, coincident with increasing river herring returns and estuary fish biomass. Despite a potentially increasing seal population, these results suggest that predator swamping from increasing forage fish may provide protection to salmon against seal predation.The presence of multiple injuries on an individual salmon was also significantly associated with the probability of a salmon having a seal‐induced injury. Lamprey wounds and lacerations on salmon were commonly associated with seal‐induced injury, suggesting a confounding effect of multiple stressors.This assessment illustrates how multi‐species diadromous restoration activities may alter predator–prey interactions in ways that support salmon conservation efforts. As demonstrated in the Penobscot River, a focus on overall ecosystem health and restoration can benefit multiple species that use the river. Insights from this study may help inform future management decisions in other human‐impacted systems where protected predators come into conflict with endangered prey. [ABSTRACT FROM AUTHOR]

The Mediterranean Sea is a high‐density maritime traffic area, particularly in the Pelagos Sanctuary. Ship strikes pose a substantial threat to fin whales (Balaenoptera physalus) according to reports from the IUCN, the IWC, the ACCOBAMS and the EU Habitats Directive.Near miss events (NMEs) were collected, as a proxy indicator of ship strikes for fin whales, along the main ferry routes crossing the Pelagos Sanctuary and adjacent western waters during 'summertime' (April to October). The 'Fixed Line Transect Med Network' carries out systematic surveys from ferries and collects data according to the 'linear transect' method. From 2008 to 2019, 13 different ferry routes were surveyed with 238,499 km monitored.Of the 2,775 fin whales encountered, 43 individuals were involved in NMEs (1.55% of the sightings). NMEs occur over the great majority of the routes monitored with enough effort and were correlated with the density index of fin whales.High‐risk areas for NMEs were identified in the central and deeper parts of the north‐western Mediterranean Sea and in some sections of the northern Tyrrhenian Sea.Of all NMEs, the majority of whales (63.4%) surfaced in front of the vessel (<50 m), leaving no time for the crew to manoeuvre the vessel. The others were travelling (26.8%) or resting (9.7%) without any noticeable reaction at the vessel.The speed of the ferries seems to play a role in the occurrence of the NME, as this parameter is significantly different (t‐test, P = 0.002) for NMEs compared to all fin whale sightings, whereas month and hour of day were not.Quantifying NMEs based on real‐time observation with observers on board, could be used as a feasible and efficient way to limit collisions, raising awareness by the crew, and testing or evaluating other potential tools that can help mitigate this threat. [ABSTRACT FROM AUTHOR]

River ecosystems are often fragmented by artificial structures, such as weirs. For anadromous species, these structures can impede access to upstream spawning sites and ultimately lead to severe population declines.This study focused on the freshwater spawning migration of the sea lamprey, Petromyzon marinus, an anadromous species threatened by habitat fragmentation across its native range. To quantify the cumulative impacts of multiple weirs on upstream‐migrating adults, and to explore the environmental factors affecting migratory movements, passive acoustic telemetry was applied to 56 individuals during their spawning migration in the heavily fragmented River Severn basin, UK.While 89% of tagged sea lamprey passed the first weir upstream of the release site on the main river, only 4% passed the fifth weir. For 85% of migrants, the upstream extent of migration was immediately downstream of a weir. Individuals that passed weirs upstream of the release site (n = 50) took 21.6 ± 2.8 days to reach their most upstream location, experiencing cumulative passage times at weirs of 15.7 ± 2.8 days; these delays constituted a median of 84% of total upstream movement times.Multistate models showed that the weir passage rates of sea lamprey in tidal and non‐tidal areas increased significantly when downstream river level and discharge were elevated. Upstream‐to‐downstream changes in direction were frequent downstream of weirs, but rare in unobstructed river sections.The results provided evidence for a cumulative effect of multiple weirs on sea lamprey movements, substantially delaying upstream migrants and limiting their spawning to atypical habitat. The results also demonstrated the crucial roles of high tides and elevated discharge events in enabling weir passage. Although the Severn Estuary features conservation designations for sea lamprey, this study reveals that barriers are inhibiting their upstream migration, a problem that should be addressed to assist sea lamprey conservation. [ABSTRACT FROM AUTHOR]

Human impacts on marine ecosystems are increasing and the number of fish species listed in the Red List is constantly growing. In the Mediterranean Sea, seven of the 10 bony fishes defined as Threatened by the IUCN are known to be vocal, including the target species of this study: the shi drum (Umbrina cirrosa Linnaeus, 1758) and the brown meagre (Sciaena umbra Linnaeus, 1758). As a result, non‐invasive passive acoustic monitoring (PAM) can be used to pinpoint their distribution at sea. However, for PAM to be effective, reliable acoustic discrimination is required because the sounds they emit during reproduction are remarkably similar (i.e. short broadband pulsed sounds).The shi drum and the brown meagre are closely related, elusive, vocal sciaenids, partially overlapping in their ecological niche. During summer 2019, three PAM surveys were conducted along the tidal inlets of the Venice lagoon (Italy). Here, the calls of both species have been recognized according to their temporal features: shi drum sounds were made up of a lower number of longer pulses with a different envelope, repeated at a lower rate than those of the brown meagre. Further, shi drum and brown meagre sounds of different origins (aquaculture and semi‐natural conditions) were analysed and compared with those collected during the survey of the study area in order to validate the field collected data.Call discrimination allowed for a fine‐scale species mapping, showing a partially overlapping distribution of the two species along the inlets. This is the first case in which two sciaenids have been documented to share their reproductive habitat in the Mediterranean Sea.This study demonstrates that it is feasible to acoustically monitor the target species even in those parts of the Mediterranean Sea where they co‐exist. This, in its turn, could provide managers with the required data for effective conservation measures to be implemented. [ABSTRACT FROM AUTHOR]

Detailed knowledge about the distribution of species in need of protection is required for the management of Marine Protected Areas, a major tool to reduce marine biodiversity loss. Such knowledge is deficient for most marine invertebrates.Axinella polypoides is a marine sponge included on the list of protected species by the Barcelona Convention (1976) and the Bern Convention (1987). This large and erect species has an important ecological role in habitat forming and benthic–pelagic coupling.Bathymetrical, geographical and ecological data over the last 60 years were collated from publications and reports, together with new surveys to assess the distribution and protection status in Liguria of A. polypoides. It identified a more widespread distribution than previously thought, which points at a general need for dedicated investigations on the occurrence of species that require protection.Bathymetrical distribution was trimodal, with peaks corresponding to different geomorphological settings: coastal cliff bases (around 38 m depth), inner shelf shoals (52 m) and rocks amidst coarse sediment on the outer shelf (79 m). Density was significantly greater at the shallowest depths. The species was mostly found in the coralligenous biocoenosis, in association with other characteristic species or forming a monospecific facies.On (sub)vertical cliffs, A. polypoides often exhibited an unusual cane shape, rather than the typical bushy morphology, thus causing confusion with the congeneric A. cannabina, a more southern species. Records of the latter in the Ligurian Sea therefore need confirmation.Only a minority (22.6%) of A. polypoides records were in Marine Protected Areas, the remainder being located in areas with no current environmental protection plans in place. While the occurrence of this species in MPAs remained stable over the decades, the only quantitative historical data available indicated that populations in non‐protected areas were declining owing to anthropogenic impacts (fishing and anchoring). [ABSTRACT FROM AUTHOR]

The Adriatic Sea is one of the Mediterranean areas most heavily impacted by fishing and other human stressors. The northern part of the basin has been certified as an Important Marine Mammal Area because of the regular occurrence of common bottlenose dolphins, Tursiops truncatus.Boat surveys, totalling 76 days at sea and 10,711 km of navigation, were conducted between April 2018 and October 2019 to assess cetacean abundance within a 3,000‐km2 area off Veneto, Italy. Bottlenose dolphins – the only marine mammal species observed – were encountered on 52 days and were tracked for 81 h and 26 min, resulting in 15,066 dorsal fin photographs of high quality and resolution.Various capture–recapture models were applied on individual photo‐identification datasets. Model‐based estimates indicate that approximately 600 individuals occurred within the study area during the sampling period in both years. Abundance varied monthly: minimum estimates were obtained in May 2018 (291 individuals; 95% CI 134–630) and May 2019 (121; 95% CI 20–721), whereas maximum estimates were obtained in September 2018 (385; 95% CI 310–477) and October 2019 (494; 95% CI 378–645).Evidence provided by this study can be used to complement and validate coarse 'snapshot' information from recent aerial surveys of the entire Adriatic Sea, and to enforce management action mandated by the European Community (EC) Habitats Directive and Marine Strategy Framework Directive, as well as guiding the EC's Maritime Spatial Planning. [ABSTRACT FROM AUTHOR]

Publication is an important stage in the research process, but determining the impact of published research on environmental outcomes is a complex challenge that is seldom undertaken. In 2016, a published study used acoustic telemetry techniques and drift sampling to demonstrate that environmental flow releases triggered downstream spawning migrations by a threatened fish species, the Australian grayling (Prototroctes maraena). The study provided support for the use of these types of releases to mitigate some of the effects of river regulation on fishes.The impacts of this research and its publication in Aquatic Conservation: Marine and Freshwater Ecosystems were thoroughly reviewed to identify benefits to water managers, researchers, institutes, and the wider community.Five areas in which this research, and its publication, had a recognizable impact are enhanced confidence for water managers in undertaking actions; greater acceptance in the wider community of environmental flow releases; enhanced relationships among water managers; the credibility arising from the work being published in a peer‐reviewed journal; and setting a foundation for further evidence‐based management. [ABSTRACT FROM AUTHOR]

1.The brown meagre (Sciaena umbra) is a demersal sciaenid fish recognized as indicative of good environmental quality and is defined as an umbrella species for the ecological community of rocky coastal habitats. Sciaena umbra is classified as a Vulnerable fish species by the International Union for Conservation of Nature (IUCN) and knowledge on the distribution of its spawning habitats is essential for its conservation.2.Passive acoustic monitoring (PAM) is a suitable tool to monitor S. umbra distribution because of the high consistency, over space and time, of the communication sounds that this species emits during the reproductive period, with irregular or regular rhythms, or with calls merging into a chorus.3.During the summer of 2019, the presence of this species was investigated acoustically at 40 listening points distributed along the tidal inlets that connect the Venice lagoon with the open sea.4.Longer sounds, comprising a higher number of faster repeated pulses, were found during the chorus and were used as a proxy of spawning activity; similar sound features have been recorded in different captive Sciaenids during spawning.5.The three inlets were classified as more or less suitable for spawning on the basis of the vocal rhythms identified, demonstrating a clear preference along a north–south gradient and indicating higher spawning activity in the internal‐facing areas of the inlets, compared with the seaward‐facing areas. The chorus occurred in localized areas consistently throughout the breeding season, suggesting that spawning is concentrated in preferred areas.6.For the first time a relationship between the sound features and vocal rhythms of fish has been highlighted by an in situ study. This validates the use of the chorus as a reliable natural indicator of S. umbra breeding sites, and in turn suggests a potential non‐invasive approach based on PAM for mapping the key reproductive areas of this vulnerable species in the Mediterranean Sea. [ABSTRACT FROM AUTHOR]

Spinner dolphins, Stenella longirostris, are the primary target for marine mammal tourism in Egypt. The present study investigated the short‐term effects of tourist presence on the behaviour of spinner dolphins at Sha'ab Samadai (Samadai Reef), in the southern Egyptian Red Sea.The reef has a large central lagoon where a population of spinner dolphin regularly rest from mid‐morning to mid‐afternoon; visitors are permitted to snorkel in the southern part of the lagoon, but not in the northern closed zone that the dolphins mainly use.Dolphin behaviour was monitored both on days when tourist boats were present and on days when they were absent. In the presence of tourists the proportion of time that the dolphins spent resting was reduced by two‐thirds, whereas the times spent milling, travelling, and showing avoidance behaviour all increased.Furthermore, upon using Markov chain modelling to investigate the effect of tourist presence on the transition probabilities between dolphin activity states, significant changes were found in 10 of the 25 possible behavioural transitions, including increased probabilities of transitioning from resting to milling or travelling, from milling to travelling or avoiding, and from travelling to avoiding.These findings raise concerns that despite the management measures in place, tourist activities affect the dolphins' behaviour to a greater extent than was previously apparent, with potential long‐term negative effects on their energy budget. The study led to proposals for amending the zoning of the site and for strengthening the regulations for tourist vessels. [ABSTRACT FROM AUTHOR]

The coast of Fujian Province is a key area for the Indo‐Pacific humpback dolphin (Sousa chinensis), but the characteristics of their preferred habitats are poorly defined.The species distribution model, MaxEnt, was used to predict suitable habitat distributions of humpback dolphins in Fujian, China. The model indicated that the distance to the coastline (63.5% contribution), chlorophyll‐a levels (20.2%) and the bathymetry (15.6%) were important predictors of humpback dolphin habitats.The model predicted 2,043.96 km2 of highly suitable habitat that was concentrated in five areas. Four are known to be within the area of the current distribution of humpback dolphins; Putian was identified as a new area with suitable habitat, however, it is unclear if dolphins are present.The predicted locations of suitable humpback dolphin habitats provided in this study should be the focus of future research and nature reserve designs. [ABSTRACT FROM AUTHOR]

West Bay is located along the south‐west portion of Galveston Bay, Texas, and has been delimited as a bay, sound, and estuary (BSE) common bottlenose dolphin (Tursiops truncatus) stock area under the Marine Mammal Protection Act of 1972. The most recent abundance estimate available for the West Bay BSE stock is from 2001 and is considered outdated for management purposes.This study provides an updated abundance estimate using photo‐identification capture‐mark‐recapture (CMR) data collected from West Bay during the winter of 2014 and summer of 2015. The CMR data were analysed using both Pollock's robust design models and Poisson‐log normal mark‐resight models.Differences between the model types are discussed, and the abundance estimates derived from the mark‐resight models are recommended for management use (50.63 [unconditional SE 2.23] in the winter and 44.36 [unconditional SE 1.18] in the summer).Whereas the updated abundance estimates are higher than the previously reported estimates, which varied between 28 and 38, they still indicate that West Bay supports a small population of bottlenose dolphins. As a result, the West Bay BSE stock should be closely monitored for impacts, particularly those related to human caused stressors. [ABSTRACT FROM AUTHOR]

Important marine mammal areas (IMMAs) are discrete portions of habitat, important to marine mammal species, that have the potential to be delineated and managed for conservation. Although IMMAs are not a blueprint for marine protected areas or other conservation designations, they are useful for providing a foundation for marine spatial planning and systematic conservation planning that can then lead to protected areas or special spatial regulations. To be most useful for supporting management and conservation, however, the information coming out of IMMAs needs to reflect current conditions.An 'early warning system' is proposed with a generic set of indicators to flag when marine mammal species in IMMAs require management interventions due to changing distributions or decreasing populations. Rather than signifying that quantitative thresholds have been reached, these indicators comprise alerting information derived from visual or acoustic census, satellite imagery analysis, whale‐watching logs, or increases in mortality reported by stranding networks that can trigger additional targeted research.Although it is possible that in some regions data will be sufficient to provide quantifiable indicators, the system is meant to rely on existing data sources, and be adaptable to the circumstances of each region.Regional expert groups can utilize early warning system information and feed it into IMMA‐related spatial planning in two ways: by nominating additional areas of interest, and by providing a scientific rationale for revising IMMA boundaries, to be considered at the next decadal IMMA regional expert workshop.IMMA‐driven consolidation of information that is as current as possible will prove valuable for enhancing regional cooperation to conserve marine mammals, and will be useful as countries implement new protected areas to conserve marine mammals and other marine biodiversity. [ABSTRACT FROM AUTHOR]

The population of bottlenose dolphins in eastern Scotland has undergone significant range expansion since the 1990s, when a Special Area of Conservation was established for the population.Distribution of this population is well described within areas of its range where intensive work has been carried out, such as the inner Moray Firth, St Andrews Bay and the Tay estuary area. However, elsewhere in their range, habitat use is less well understood.In this study, a large‐scale and long‐term passive acoustic array was used to gain a better understanding of bottlenose dolphin habitat use in eastern Scottish waters, complementing and augmenting existing visual surveys.Data from the array were analysed using a three‐stage approach. First, acoustic occupancy results were reported; second, temporal trends were modelled; and third, a spatial–temporal‐habitat model of acoustic occupancy was created.Results from the acoustic occupancy are in agreement with visual studies that found that areas near known foraging locations were consistently occupied. Results from the temporal trend analysis were inconclusive. Habitat modelling showed that, throughout their range, bottlenose dolphins are most likely to be detected closer to shore, and at a constant distance from shore, in deeper water. [ABSTRACT FROM AUTHOR]

Understanding the temperature tolerances of organisms is critical because the thermal regimes of freshwater ecosystems are changing globally. Native freshwater mussels are sensitive to increasing water temperatures because of their physiology and unique life history. Detailed knowledge on lethal temperatures for mussels has been limited to less than 5% of the species known to occur in North America, and little is known about the thermal tolerances of mussel species from rivers within the south‐western USA.To determine the effects of elevated water temperature on mussels, the upper thermal tolerances of larvae (glochidia) for the following species across four basins in Texas (Neches, Guadalupe, San Antonio, and Colorado) were tested: Amblema plicata, Cyclonaias necki, Fusconaia mitchelli, Lampsilis bracteata, Lampsilis hydiana, Lampsilis satura, Lampsilis teres, and Obovaria arkansasensis.Glochidia were acclimated to 27°C across a range of experimental temperatures (30–39°C) in 24‐h standard acute laboratory tests. The median lethal temperature (LT50) among glochidia averaged 32.4°C and ranged from 26.9 to 36.4°C.Thermal tolerances differed significantly among and within species, and by season. Comparing these results with current water temperatures in central and east Texas indicated that populations of the focal species studied are at risk from rising environmental temperatures and, as a consequence, their long‐term viability will be challenging in future years. [ABSTRACT FROM AUTHOR]

Cage diving is the most important activity for the sustainable use of white sharks (Carcharodon carcharias). However, information related to their behaviour during ecotourism is scarce.This study provides useful information for monitoring C. carcharias during cage‐diving activities around Guadalupe Island, Mexico. Surface behaviour of 106 white sharks was recorded for 87 days on‐board six cage‐diving boats in 2012, 2013, and 2014.Of the observed sharks, 63% were immature specimens (n = 67) and 37% were considered mature (n = 39). Seventy‐one per cent were males (n = 75) and 29% were females (n = 31).Interactions were classified into one of the 11 behaviours: parading, close inspection, horizontal attack, vertical attack, bait catching, feeding, not feeding, buoy catching, encounter, escape, and staying.Parading, close inspections, and horizontal attacks were performed more often by mature males, whereas immature females performed more vertical attacks, with no differences between mature and immature males.A total of 1,542 ethograms were registered. Each ethogram consisted on average of 6.3 ± 5.6 behaviours with a significant transitional pattern from horizontal attacks to parading and close inspections, and from vertical and horizontal attacks to bait being caught.A pattern related to feeding in a simple stimulus response reflex was observed. The shark's length seems to play an important role in the efficiency of the attacks, presumably resulting from the experience of mature individuals. Intentional feeding should be avoided to prevent negative effects related to ecotourism.This study constitutes a baseline for future research on white shark behaviour. It can be applied in other regions regardless of environmental conditions, quantity and size of the boats, and types of bait. Using this standard method could improve the monitoring, management, and conservation of this vulnerable species. [ABSTRACT FROM AUTHOR]

Fisheries and the presence of low‐head obstacles are considered major threats for anadromous lampreys, including the sea lamprey (Petromyzon marinus). Nonetheless, research is still needed to increase our understanding of their effect and to implement effective conservation and management measures. Petromyzon marinus receives conservation protection in Europe through the Bern Convention and the European Habitats Directive and is listed as 'Vulnerable' in Spain.The aim of this study was to investigate the impact of low‐head obstacles and fisheries on the spawning migration of P. marinus in the highly impounded River Ulla (in north‐west Spain). Nineteen lamprey were radio‐tracked in 2012 and 2013, and historical data (2002–16) on fishing captures were analysed (n = 25 607) to provide a population‐level approach.The retention of individuals by low‐head obstacles, including pesqueiras constructed for lamprey fishing, and extraction by fisheries at those structures, caused a significant reduction of migrants upstream of each impoundment (mean: 24% individuals per obstacle). A delay in migration (mean: 6.3 days per obstacle) seems to be an important limiting factor for lamprey conservation in this river. Thus, based on the recorded delay, lamprey would need c. 5 months to pass the 23 obstacles present before reaching the first spawning areas and 9.5 months to cover the accessible river section (45 obstacles), which is far longer than the 3–5 months of spawning migration of P. marinus in this river.Consequently, obstacle removal or permeabilization should be prioritized for lamprey conservation in this river. This would reduce migration delay, the retention of individuals, and the catchability of lamprey at pesqueiras (with alternative routes to avoid traps). Basic information on fisheries management is still lacking, especially on stock exploitation rates and on lamprey population status and dynamics. Future studies should also investigate the role of lamprey exchange between basins (a lack of homing) in the resilience of lamprey populations. [ABSTRACT FROM AUTHOR]

Common bottlenose dolphins (Tursiops truncatus) are found in temperate and tropical waters of the world across a wide range of habitats. Along Florida's north‐western coast, this species resides in the bays, sounds, and estuaries (BSE) and coastal (CST) waters of the northern Gulf of Mexico. The National Marine Fisheries Service has identified one CST (Northern Coastal Stock) and seven adjacent BSE dolphin stocks, including the St Andrew Bay BSE Stock.Baseline data are critical to assess the impacts of ongoing and future anthropogenic stressors on these stocks. Currently, there is no comprehensive abundance estimate for the St Andrew Bay BSE Stock, and there are limited data on distribution patterns and site fidelity for this stock. In addition, little is known about the Northern Coastal Stock hypothesized to range from the Big Bend of Florida to the Mississippi River Delta, inclusive of the CST waters adjacent to St Andrew Bay.The goals of this study were to conduct photographic‐identification surveys during 2015 and 2016 to determine abundance, distribution, and site fidelity of common bottlenose dolphins in the St Andrew Bay BSE Stock over four primary periods (July and October 2015, and April and October 2016).St Andrew Bay BSE dolphin abundance was lowest in April 2016 (199, 95% confidence interval [CI] 173–246), followed by July 2015 (249, 95% CI 199–338), and highest in October 2015 (299, 95% CI 259–361) and October 2016 (315, 95% CI 274–378). Few individuals were sighted in both BSE and CST waters (N = 25/353; 7%), and this fact, taken in tandem with limited connections between the BSE and CST environments, suggests that there may be minimal overlap between the St Andrew Bay BSE and Northern Coastal Stocks. [ABSTRACT FROM AUTHOR]

Flapper skates (Dipturus intermedius) were once widespread in European shelf waters but are currently classified as critically endangered by the International Union for Conservation of Nature due to historical overexploitation. Novel monitoring approaches are needed to assess the efficacy of management measures, such as dedicated marine protected areas, for the conservation of relict skate populations.Flapper skates possess distinctive dorsal spot patterns, which could potentially be used for individual recognition using photo‐identification (photo‐ID) approaches. This study assessed the potential of photo‐ID as a method for individual recognition of a relict population of skates within a dedicated marine protected area in western Scotland (UK), which has long been targeted by directed recreational angling. A collection of 486 photographs of 373 separate skate capture events from 2011 to 2016, taken with standard mobile phones and compact cameras, was studied using visual pairwise comparison methods to determine number of individuals and recapture rates.Results indicated that adult flapper skates were individually recognizable with a high degree of certainty through comparison of spot patterns, assuming appropriate lighting conditions. A total of 226 individuals were identified, of which 77 (34%) were recaptured at least once. The average recapture interval was 308 days (SE: 29.4 days), with the longest recapture interval to date being 4.4 years. Spot patterns among recaptured tagged or otherwise uniquely identifiable skates were found to remain stable over timescales of months to >1 year.Results indicate that photo‐ID, based on photographs sourced through citizen science approaches, can provide a low‐cost alternative means of monitoring flapper skate presence and distribution for the purposes of underpinning management decisions. [ABSTRACT FROM AUTHOR]

Abstract: Biological invasions are widely regarded as the second major cause of the current global biodiversity crisis. Freshwater environments in particular include many habitats and species of conservation concern. Among those, amphibians are threatened worldwide by habitat loss and by the introduction of alien taxa, including pathogens and fish. The North American mosquitofish Gambusia spp. have been introduced throughout the world for the biological control of mosquitoes, and have established alien populations in over 110 countries. Their impact on native freshwater vertebrates, especially in Europe, is still poorly known. Here, the predatory impact of mosquitofish on the larval stages of four European amphibian species (Hyla intermedia, Triturus carnifex, Pelophylax kl. hispanicus, and Bufotes balearicus), locally abundant in Central Italy, has been investigated under laboratory conditions to assess whether any difference occurs in species vulnerability and interactions with the predator, as their breeding sites are often invaded by mosquitofish. Larval mortality and fish attacks, as well as observations on fish predatory behaviour, were recorded at four time intervals (10 min, 1 h, 6 h, and 24 h) and at three different prey abundances (with five, 10, and 20 larvae). A significant difference in predation rate for species, exposure time, and larval abundance occurred, with H. intermedia being the most vulnerable species and B. balearicus being the least vulnerable species. An increase in exposure time increased the rate of predation, whereas small groups of larvae (i.e. <10 individuals) appeared to be far more vulnerable to fish attack compared with the larger groups. Mosquitofish show considerable potential to prey upon the larvae of European amphibians, representing a serious threat for their conservation. Appropriate management and legislative strategies are thus necessary to prevent the further introduction and spread of this alien fish in natural environments. [ABSTRACT FROM AUTHOR]

Abstract: Globally, seagrasses and other estuarine habitats are under threat from a range of human disturbances, including boating‐related activities. The fixed, block‐and‐chain swing moorings used to secure boats in many countries can create visible scars in seagrass meadows and remove other benthic organisms. Losses of seagrasses in two estuaries in New South Wales (NSW), Australia, were quantified using aerial imagery and used to estimate estuarine habitat damage across the remainder of the state. The rate of mooring scar development was approximated and factors influencing the size of mooring scars were identified. Individually mapped mooring scars in meadows of the endangered Posidonia australis ranged from 55 to 706 m2, and were generally larger than those in the more opportunistic seagrass Zostera muelleri subsp. capricorni (22–342 m2). Scar size in both species of seagrass increased significantly with depth and boat length. The rate of increase in the size of mooring scars amongst P. australis was roughly linear over 4.8 years, averaging 6.3 m2/month up to a maximum of 16.7 m2/month for one 16‐m yacht. Across all of NSW, it was estimated that currently leased moorings were causing losses of 129 884 m2 of P. australis and 93 940 m2 of Z. capricorni, and disturbing 2 790 907 m2 of non‐vegetated soft sediments. NSW seagrass loss estimates relate only to damage from current moorings and could be underestimated by ~41% for P. australis if estuaries contain many old scars that remain after the relocation of moorings (as has occurred in Lake Macquarie). Mandating the use of moorings that do not rely on a chain dragging on the sea bed would greatly reduce future physical damage of benthic habitats and enable some recovery from legacy effects. [ABSTRACT FROM AUTHOR]

Abstract: Relatively little is known about seabird–fishery interactions (i.e. bycatch) for the U.S. North‐east and mid‐Atlantic, despite concerted efforts to document observed interactions since 1989. Fisheries observer data were used to estimate seabird–fishery interactions for 10 species and six gear types that operated within the US Northeast and mid‐Atlantic from 1996 to 2014. Hierarchical Bayes estimation was used and accounted for temporal, spatial, and operational considerations inherent in the data through post‐stratification. Over the 19‐year study period, 48 821 (coefficient of variation [CV] = 0.03) seabirds were estimated to have interacted with commercial fishing gear, resulting in an average of 2570 interactions per year. Trends in estimated interactions were explored using the marginal posterior distributions, with the majority of interactions pertaining to gillnets and shearwaters/fulmars. Comparison with previous work highlighted the need for consistency in data preparation, making it easier to compare relative trends in seabird bycatch estimates for the region. Future assessments should focus on providing context for the interaction estimates, so that population‐level impacts can be inferred and the necessary conservation measures enacted. [ABSTRACT FROM AUTHOR]

Abstract: Following a shark attack, local governments often rapidly respond by implementing indiscriminate shark culls. These culls have been demonstrated to have substantial localized and adverse effects on a variety of marine organisms, and therefore there is an increasing need for an eco‐friendly alternative that maximizes both beachgoer and marine organismal safety. In response to such culls, the novel magnetic barrier technology, the Sharksafe Barrier was developed and rigorously tested on a variety of sharks implicated in shark attacks (e.g. bull sharks – Carcharhinus leucas and white sharks – Carcharodon carcharias). Although these studies exhibited promise in shark swim pattern manipulation and C. leucas exclusion, research was lacking in assessing if the technology could serve as an alternative to shark nets, or more specifically, if it could exclude motivated C. carcharias from bait. Using a 13 m × 13 m square exclusion zone, this study aimed to test the C. carcharias exclusion capabilities of the Sharksafe Barrier while additionally assessing the long‐term structural integrity of the system. After 34 trials and approximately 255 hours of total video collected over two years, data illustrate that all interacting C. carcharias were successfully excluded from the baited Sharksafe Barrier region, whereas teleosts and other small elasmobranch species were not. In addition, the long‐term deployment potential of this barrier system held promise owing to its ability to withstand harsh environmental conditions. Therefore, with the successful exclusion of a second large shark species, C. carcharias, from a baited region, continued long‐term research and implementation of this system at other locations should be considered to assess its viability and overall success as a bather and shark protection system. [ABSTRACT FROM AUTHOR]

1. Human-mediated threats have led to the rapid decline of species inhabiting freshwater ecosystems, and among the groups most affected are freshwater mussels of the family Unionidae. As a result, species translocation is increasingly used in conservation programmes, yet experimental evidence documenting the success of this strategy is limited. 2. The goal of this study was to examine the effects of translocation on survival probability, shell growth and body condition of a state-threatened (Quadrula houstonensis) and common (Amblema plicata) species of freshwater mussel in the San Saba River, located in a West Gulf Coastal Plain river system, USA. 3. Survival probability estimated from a joint live and dead encounter model was high (> 0.85) and varied by treatment for both species. However, differences in survival probability between resident and transplant treatments were relatively small for A. plicata (0.01) and Q. houstonensis (0.12). Generalized additive mixed models of yearly proportional growth and linear mixed models of Fulton's K index for A. plicata varied by treatment and were lower in transplant treatments. Shell growth of Q. houstonensis was unaffected by translocation; whereas, Fulton's K was higher in the transplant treatment. 4. Methods used to translocate mussels were important factors leading to high survival and limited impacts to shell growth and body condition in this study. Differences in shell growth rate between treatments are attributed to possible differences in habitat quality between sites. 5. Our results demonstrate that A. plicata and Q. houstonensis are tolerant of translocation, despite the broad assumption that translocation is detrimental to mussels. Thus, there is a continuing need to study species' responses to translocation to test and improve the ecological soundness of this strategy, particularly because climate change and other human stressors will exacerbate the need to implement conservation measures such as translocation in future decades. [ABSTRACT FROM AUTHOR]

Pelagic longline fisheries for relatively fecund tuna and tuna-like species can have large adverse effects on incidentally caught species with low-fecundity, including elasmobranchs., Analyses of observer programme data from the Fiji longline fishery from 2011 to 2014 were conducted to characterize the shark and ray catch composition and identify factors that significantly explained standardized catch rates. Catch data were fitted to generalized linear models to identify potentially significant explanatory variables., With a nominal catch rate of 0.610 elasmobranchs per 1000 hooks, a total of 27 species of elasmobranchs were captured, 48% of which are categorized as Threatened under the IUCN Red List. Sharks and rays made up 2.4% and 1.4%, respectively, of total fish catch. Blue sharks and pelagic stingrays accounted for 51% and 99% of caught sharks and rays, respectively., There was near elimination of 'shark lines', branchlines set at or near the sea surface via attachment directly to floats, after 2011., Of caught elasmobranchs, 35% were finned, 11% had the entire carcass retained, and the remainder was released alive or discarded dead. Finning of elasmobranchs listed in CITES Appendix II was not observed in 2014., There were significantly higher standardized shark and ray catch rates on narrower J-shaped hooks than on wider circle hooks. Based on findings from previous studies on single factor effects of hook width and shape, the smaller minimum width of the J-shaped hooks may have caused the higher shark and ray catch rates. For sharks, the effect of hook width may have exceeded the effect of hook shape, where small increases in shark catch rates have been observed on circle vs J-shaped hooks., Shark and ray standardized catch rates were lowest in the latter half of the year. Focusing effort during the second half of the year could reduce elasmobranch catch rates., Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the effects of a circle hook ring on catch rates of target fish species and bycatch rates of sea turtles, elasmobranchs, and non-commercial fish in a shallow-set Italian swordfish longline fishery., Results were compared from 65 sets from six commercial fishing vessels totalling 50 800 hooks in which ringed and non-ringed 16/0 circle hooks with a 10° offset were alternated along the length of the longline. In total, 464 individuals were caught in the 4 years of experiment, with swordfish ( Xiphias gladius) comprising 83% of the total number of animals captured. Catch rates of targeted swordfish were significantly higher on ringed hooks (CPUEringed hooks = 8.465, CPUEnon-ringed hooks = 6.654)., Results indicate that ringed circle hooks captured significantly more small-sized swordfish than non-ringed circle hooks (27.7% vs. 19.5%, respectively)., For species with sufficient sample sizes, the odds ratio (OR) of a capture was in favour of ringed hooks; significantly for swordfish (OR = 1.27 95%CI 1.04-1.57), and not significantly for bluefin tuna ( Thunnus thynnus) (OR = 1.50, 95%CI 0.68-3.42) nor for pelagic stingray ( Pteroplatytrigon violacea) (OR = 1.13, 95%CI 0.54-2.36). All six loggerhead turtles ( Caretta caretta) and three of the four blue sharks ( Prionace glauca) were captured on ringed hooks, however, the small sample sizes prevented meaningful statistical analysis., In summary, results from this study suggest that the addition of a ring to 16/0 circle hooks confers higher catchability for small-sized commercial swordfish, and does not significantly reduce catch rate of bycatch species and protected species in a Mediterranean shallow pelagic longline fishery., These findings should motivate fisheries managers to consider factors in addition to hook shape when aiming to promote sustainable fishing practices. The presence of a ring has the potential to negate some conservation benefits., Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Mobulid rays are protected in New Zealand, but the spinetail devilray Mobula japanica is caught as bycatch in skipjack tuna purse seine fisheries., Between 2005 and 2014, rays were recorded in 8.2% of observed purse seine sets. Rays were caught during summer, with a 'hotspot' (24.3% of sets) near the shelf edge off North Island over seabed depths of 150-350 m. Rays were usually brailed aboard with the tuna catch from successful sets, but were often entangled in the bunt of the net during unsuccessful sets., Observers tagged nine rays with popup archival tags to obtain preliminary information on their post-release survival, and spatial and vertical movements. Seven of the nine tags reported data, and four of those rays died within 2-4 days of release. All four rays that died had been brought aboard entangled in the bunt. The three surviving rays were all brailed aboard with the tuna catch., One surviving ray remained near New Zealand for 2.7 months during summer, and the other two migrated 1400-1800 km northward to tropical waters near Vanuatu and Fiji at minimum speeds of 47 and 63 km day−1 at the end of summer., Archive data from one ray showed that it made regular vertical movements of 25-100 m amplitude, but spent most of its time shallower than 50 m, more so during the night (89.6%) than the day (76.6%), and mainly experienced temperatures of 18−22 °C. Dives deeper than 200 m were usually made during the day or twilight., All three surviving rays typically moved between the surface and 200-300 m daily, and reached greatest depths of 649 m, 1000 m and 1112 m, respectively, substantially exceeding the previous depth record for this species of 445 m., Recommendations are made for reducing purse seine mortality of mobulid rays by avoiding areas of high ray abundance, avoiding setting on ray-associated tuna schools, and adopting best-practice methods of returning rays to the sea from the net or vessel., Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Desert spring ecosystems harbour many endemic species that are threatened with extinction owing to human activities. Springsnails (superfamily Truncatelloidea) are among the most diverse freshwater snail groups in desert springs of western North America. They occupy geographically narrow ranges, often consisting of a single spring or spring complex., Microsatellite markers were developed via high-throughput de novo sequencing for two endangered springsnail species, Juturnia kosteri and Pyrgulopsis roswellensis, endemic to springs on Bitter Lake National Wildlife Refuge (BLNWR) near Roswell, New Mexico, USA. Genetic diversity, population structure, effective population size ( Ne), and historic demography were assessed in two populations for each species., A large number of putative markers were identified, of which 14 loci for J. kosteri and 18 loci for P. roswellensis showed polymorphism. Genetic diversity and Ne were greater in P. roswellensis than J. kosteri. Significant genetic differentiation ( FST = 0.187-0.288) was found among populations for both species, indicating currently limited gene flow. Neither species showed signs of recent population bottlenecks., Analyses with microsatellite markers revealed fine-scale population genetic structure in both species, unlike a previous study using mitochondrial DNA sequences. Although these species co-occur on BLNWR, slightly different genetic characteristics between them suggest that they may have different evolutionary and demographic histories. Small Ne relative to census size indicates strong genetic drift in these populations. Future efforts should be directed to identifying causes of such strong drift., Because there are limited numbers of microsatellite markers available for springsnails, the markers identified in this study should be useful for congeners via cross-species amplification. Understanding current genetic variation and structure of these species is not only required for species recovery, but will also be useful for comparisons among many aquatic organisms endemic to springs of western North America., Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In principle, the database generated by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) offers an unparalleled opportunity to analyse trade in species of conservation concern., The value of the database is assessed in the context of trade in 47 species of seahorse ( Hippocampus spp.), all of which are included on CITES Appendix II. This listing requires that all 180 Parties to CITES (member Parties) limit exports to levels that do not damage wild populations, ensure they are obtained legally, and report their trade to CITES., An evident need for greater universal compliance with CITES reporting requirements was identified. The most glaring problem was a substantial mismatch in species and volumes between export records and import records, indicating that neither dataset is complete nor reliable., The evaluation also showed that Parties should increase compliance with CITES requirements to record all trade shipments, provide units for exports (e.g. individuals, kilograms) and identify exported taxa to species, perhaps supported by automated checking of entries., The challenges with the CITES trade database were more evident for the global trade in dried seahorses than the smaller and more easily-tracked trade in live seahorses. Nonetheless, CITES' data from 2004-2011 revealed a seahorse trade involving millions of animals, tens of species, and scores of Parties., CITES data have also proven invaluable in supporting CITES reviews of how Parties are implementing the Convention for seahorses, and in generating consequent action for their conservation., Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

1. Bycatch of non-target species in commercial fishing nets can have adverse impacts on their populations. Freshwater turtle populations are particularly susceptible to increases in adult mortality, and freshwater turtles are among the most threatened vertebrates. 2. As a case study, the population-level impacts of bycatch mortality on freshwater turtles were evaluated in Lake Opinicon, Ontario, Canada, a lake that supports a small-scale commercial fishery. Using population viability analyses, the impacts of bycatch on common snapping turtles (Chelydra serpentina), eastern musk turtles (Sternotherus odoratus), northern map turtles (Graptemys geographica), and painted turtles (Chrysemys picta) were evaluated. 3. In all four species, even low levels of additional annual female mortality as a result of bycatch were sufficient either to reduce population size or to cause extirpation of the local population within 500 years. Bycatch reduction programmes, such as seasonal closures and implementation of bycatch reduction devices, can help alleviate the risk of extirpation. Changes to fishing season length could help reduce the number of snapping turtles and musk turtles captured. Installation of simple bycatch reduction devices can exclude between 95% and 100% of snapping turtles and between 0% and 97% of the other three species, depending on the width of the exclusion device. If combined, these two bycatch reduction methods would help prevent adult female mortality and help maintain turtle populations in Lake Opinicon. 4. Although these findings are specific to the study area, the same principles apply to other areas where similar simple bycatch reduction strategies can be employed to prevent the extirpation of other freshwater turtle species. Considering the consequences of bycatch and of bycatch reduction programmes on populations provides managers with important information to support development of risk-averse conservation strategies. [ABSTRACT FROM AUTHOR]

ABSTRACT The last remaining population of Margaritifera margaritifera in the Our River (Luxembourg, Europe) has come close to extinction. It consists predominantly of adult animals and will disappear within a few years without assistance. Juvenile mussels cannot survive in the river bed interstices, which are clogged by fine sediments, and rearing methods are needed to help them through this critical period., The objectives of this study were to elucidate the best rearing conditions for juvenile mussels with respect to the food type and density of individuals in order to breed them in the laboratory to a size at which survival in the river is likely., Different food mixtures (combinations of algae, detritus and crushed red bloodworms) were fed to juvenile mussels in plastic boxes containing 500 mL of river water during a period of 110 days. To understand fluctuations in the concentrations of nitrate, nitrite and ammonium between water exchanges, these ions were analysed over a period of 8 days., The best rearing results were achieved with a combination of detritus and algae. This treatment resulted in a growth rate of 189% (up to 1.13 mm (SD ±0.30) per box) with a survival rate of 80% (101 dead mussels (SD ±163.71) per box). The optimum number of mussels per box was 200. When detritus was added to the boxes, levels of nitrite and ammonium were reduced by more than 50% compared with the initial value within 8 days. Without detritus, ion concentrations increased noticeably (ammonium >50%, nitrite >150%), probably explaining higher mortality rates., Juvenile mussels have food reserves for less than 8 days after excystment and need additional food as soon as possible after dropping from the host fish., Juvenile mussels showed the most favourable survival rate and growth rate if fed with a mixture of algae and detritus. Detritus functions not only as a food source but also as a biologically active compound which reduces harmful ions such as ammonium and nitrite in the boxes., Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

ABSTRACT The incidental catch of marine turtles is a major problem in commercial pelagic longline fisheries. The present paper reports marine turtle bycatch composition and rates from a Portuguese commercial longline fishery targeting swordfish in the South Atlantic, and investigates the effects of changes in hook style and bait type., In total, 310 longline sets were carried out between 2008 and 2012. Three different hook styles were tested, traditional J hook (9/0) and two 17/0 circle hooks (a non-offset and a 10º offset), but only one bait type was used in each set ( Scomber spp. or Illex spp.)., Two species of sea turtles were caught, the leatherback Dermochelys coriacea, and the loggerhead Caretta caretta, the latter comprising the majority of the catches. The highest mean bycatch per unit of effort values for both species combined (1.693/1000 hooks) and for the individual species (1.505/1000 hooks for loggerheads) occurred with J-style hooks baited with squid. Changing from J-style to one of the circle hooks was only significant when using squid bait (with the odds-ratios decreasing between 54% and 63%)., Hooking location was species-specific, with most loggerheads hooked by the mouth, while leatherbacks were mostly hooked externally by the flippers. Overall, 65% of all sea turtles were released alive (85% for leatherbacks compared with 63% for loggerheads)., Significant reduction of sea turtle accidental catches on the swordfish longline fisheries can be achieved by changing the J hooks to circle hooks, especially if baited with mackerel. However, such gain is species-specific and area dependent., Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

ABSTRACT Although seal scarers are widely used both to reduce economic losses at fish farms caused by seal predation and to reduce risks posed to marine mammals by offshore pile driving activities, the spatial extent of their deterrent effect on harbour porpoises is still largely unclear. However, this information is crucial to understanding the effects these devices have on the marine environment and to judge their potential as a mitigation measure., A study was conducted in the German North Sea, using passive acoustic monitoring and to some extent simultaneous aerial surveying to specifically study the spatial extent of the deterrence effects of a seal scarer on harbour porpoises. In order to link porpoise detections at various distances to actual sound levels, sound measurements of the seal scarer signal were carried out at several distances from the source., C-POD recordings revealed a significant deterrence effect on harbour porpoises up to 7.5 km away (at about 113 dB re 1 μParms), much further than previously reported. During seal scarer operation the number of porpoise detections within 750 m of the C-PODs decreased by between 52 and 95% of the value before the seal scarer was activated., An aerial survey revealed a significant decrease in porpoise density from 2.4 porpoises km-2 before to 0.3 porpoises km-2 during seal scarer operation within the 990 km2 study area, showing that the decrease in porpoise detections by passive acoustic monitoring was probably indeed the result of a decrease in porpoise abundance., These results may raise serious concerns about unwanted disturbance effects on harbour porpoises in the context of seal scarer use at fish farms and also highlight the need for caution when applied as a mitigation measure during offshore construction., Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The article discusses the steps to prevent, eradicate and mitigate the growth of invasive species inorder to protect the marine environment of that particular region. It talks about the Indo-Pacific lionfish being an invasive species which is rapidly expanding destroying native species and the ecology. It tells about the increasing population in the region harming the efforts for conservation of marine life.