The diving behaviour of little penguins in Western Australia predisposes them to risk of injury by watercraft

1. The most western little penguin colony globally, and the most northern in Western Australia (WA) is found on Penguin Island, WA. The penguins use coastal bays that are also used extensively by recreational watercraft. These penguins have been found to either dive predominantly to shallow depths of 1–5 m or to depths >8 m. It is thus hypothesized that (a) both the shallow and deeper diving penguins can potentially be disturbed or injured by these watercraft but that the risk will differ between the two diving strategies, and (b) that risk of injury for both is greater during the summer and autumn, when people are more likely to use watercraft.
2. This was tested by attaching data loggers to little penguins during chick rearing and by investigating necropsy records. Diving activity was studied for the very shallow and relatively deeper diving penguins separately, and we considered the penguins were vulnerable to interactions with watercraft when they were within the top 2 m of the water column or at the surface.
3. Shallow‐diving penguins executed >1,200 dives per day, 64% of dives occurred within the top 2 m, and they were vulnerable for approximately two‐thirds of their time at sea. The deeper diving penguins executed fewer dives. Almost half of dives were to ≥10 m, yet they were vulnerable for almost one‐third of their time at sea. Their post‐dive recovery was also longer. Thus, the risk of interaction from watercraft differs depending on the diving behaviour.
4. This study highlights the potential impact to little penguins throughout Australia and New Zealand.

     

Bycatch susceptibility in pelagic longline fisheries: are albatrosses affected by the diving behaviour of medium‐sized petrels?

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Diving for science ‐ science for diving: volunteer scuba divers support science and conservation in the Mediterranean Sea

1. Recreational diving engages 20 million people worldwide. Most of the literature refers to tropical destinations but at least 1 million dives per year take place in Mediterranean marine protected areas (MPAs).
2. Divers may negatively affect underwater habitats. However, if effectively engaged, they can contribute to science, territorial management and more sustainable local economies.
3. During 2006–2014, volunteers trained by the not‐for‐profit organization Reef Check Italia (RCI) completed 24 714 observations and 2417 dives in six Mediterranean countries, contributing to a dataset that supports scientific papers about climate change, rare and non‐indigenous species (NIS), and informs MPA management decision‐making.
4. The wide range of opportunities offered by this dataset is illustrated with two examples relevant to marine conservation in the context of MPA management. They concern: (i) the spread of the NIS Caulerpa cylindracea along the Ligurian coasts, with a focus on Portofino MPA, and (ii) the distribution and abundance of protected species in the Portofino MPA.
5. A diver‐focused survey showed that RCI volunteers are highly committed, and that participation in RCI activities has led to a better understanding of, and a sense of stewardship towards, favoured dive sites and the marine world. Knowing who volunteers are, and why they volunteer in their favourite sector, is crucial to designing citizen‐science based projects able to achieve their multiple goals.

Copyright © 2016 John Wiley & Sons, Ltd.     

Ecological risk assessment of elasmobranchs caught in the Gulf of Papua prawn fishery

1. One-third of all elasmobranch species currently known to occur in Papua New Guinea are taken as bycatch in the Gulf of Papua trawl fishery. An ecological risk assessment was conducted on the 16 species of sharks and 23 species of rays caught by the fishery.
2. Eight species were classified to be at low risk, 28 species were at medium risk while three species – Rhynchobatus palpebratus (eyebrow wedgefish), Carcharhinus coatesi (Australian blackspot shark) and Maculabatis astra (blackspotted whipray), all endemic to New Guinea and northern Australia – faced the highest level of risk from the fishery at current fishing levels.
3. There is potential for more vessels to enter the fishery in future, which is likely to elevate the risk for a greater proportion of elasmobranch species. Ongoing monitoring of bycatch levels, supported by biological and ecological studies on frequently caught species, is required to assess and manage risk in the future.
4. The development and use of trawl excluder devices or bycatch reduction devices in this fishery have the potential to reduce bycatch levels and reduce risk levels.

     

Natural and anthropogenic drivers of foraging behaviour in bottlenose dolphins: Influence of shellfish aquaculture

1. In the coastal environment, marine mammals are exposed to one of the fastest growing food production sectors; namely, the shellfish farming industry. Identification of critical habitats, such as foraging grounds in highly human‐impacted areas, is essential to species conservation. Therefore, understanding the variables that influence a species' foraging behaviour is important for their conservation, especially for long‐lived mammals such as cetaceans.
2. The aims of this study were (a) to identify and quantify the environmental and anthropogenic drivers of wild bottlenose dolphin (Tursiops truncatus) foraging behaviour, and (b) to investigate whether the shellfish farming industry influences the behaviour of this species.
3. Behavioural observations were conducted along the north‐western coast of Spain, an area affected by intensive human activities, particularly the shellfish aquaculture industry.
4. A multi‐modelling approach highlighted the importance of shellfish farm areas as a foraging ground for bottlenose dolphins. Dolphins were predicted to be more likely found foraging inside shellfish farm areas than outside (57% vs. 43%).
5. Variability in bottlenose dolphin behaviour is likely a result of the interactions of environmental and anthropogenic drivers with prey availability and the physiological needs of the dolphins. Although shellfish farm areas provide high prey density for dolphins, they can also pose threats in a number of ways (i.e. collisions with vessels, entanglement with ropes, habitat loss, noise and water pollution).
6. From a conservation perspective, aquaculture management should consider the presence of dolphins foraging and minimize the associated risks that this industry may pose to these coastal cetaceans.

     

Dolphin population specialized in foraging with artisanal fishers requires zero-bycatch management to persist

1. The small population paradigm assumes that populations with low numbers of individuals intrinsically have a high probability of extinction. The small population of Lahille’s bottlenose dolphins Tursiops truncatus gephyreus that specializes in foraging with artisanal fishers in Laguna, southern Brazil, faces human pressures including bycatch in fishing gear. The viability of this population was modelled over 30 and 100 years under different levels of bycatch, including the current scenario of two bycatches every year, two scenarios with higher incidence of bycatches and three management scenarios. The sensitivity of predicted growth rates to fixed-proportion and observed-variation changes in life history parameters was explored.
2. The current scenario predicted a declining population (r = −0.014; λ = 0.986) with a high probability of extinction in the long term (PE = 0.71). A small increase in bycatches would result in a marked increase in the probability of extinction. Management scenarios seem promising, but only the zero-bycatch management scenario would make the difference between a declining and an increasing population.
3. As expected for slow-growing species, population growth rate was most sensitive to proportional changes in adult female and juvenile survival. However, considering observed variation in vital rates, population dynamics were most influenced by variation in reproductive rates.
4. To determine the highest priority for management action, another simulation was made of how additional threat scenarios of recognized human activities (i.e. bycatch influencing adult survival and increased underwater noise or pollution influencing calf survival) would affect population dynamics. Population growth rate was very sensitive to changes in adult bycatch (especially females), as expected, and only subtly sensitive to a reduction in calf survival.
5. The current level of bycatch is unsustainable. Bycatch needs to be eliminated to maximize the probability of long-term persistence of this dolphin population. However, this population’s persistence could be threatened by natural variation in reproductive rates.

     

Tori‐lines with weighted branch lines reduce seabird bycatch in eastern South Pacific longline fishery

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Recreational scuba diving in a groundwater ecosystem: Disturbance mechanisms,ecological impacts and stakeholder perceptions

1. Ecological damage by scuba divers has been extensively studied in marine ecosystems, particularly coral reefs, whereas the impacts on freshwater environments such as groundwater springs is unknown. In the Silfra groundwater fissure in Iceland, a vast increase in diver entries has occurred during the last decade, prompting concerns over potential ecosystem impacts and visitor carrying capacity.
2. Here, a mixed‐method approach was used to assess the impacts of scuba diving in Silfra. (a) Divers were recorded under water to observe the mechanisms of diver‐related disturbances, (b) benthic material was collected along transects in Silfra and the undisturbed fissure Flosagjá to compare biofilm biomass and zoobenthic communities between and within fissures, and (c) the perceptions and experiences of stakeholders surrounding the dive tourism in Silfra were explored.
3. Underwater observations showed that 91.4% of the divers caused at least a single disturbance, resulting in biofilm detachments and/or sediment stirring. Diver fins caused the most frequent disturbances, predominantly through fin‐generated currents but also by directly contacting the substrate. Benthic biofilm biomass was lower in Silfra than Flosagjá and exhibited a negative correlation with dive‐use. Some disturbance‐tolerant zoobenthic groups exhibited moderate to strong correlations with dive‐use.
4. All stakeholders had negative perceptions towards increasing diver entries, but although entry limitation could improve tourism quality, disturbance might only minimally be reduced as springs like Silfra may be particularly sensitive.
5. Springs are characteristically stable and uniform environments that can be vulnerable to disturbance. Their use for scuba diving should be carefully managed through a holistic approach and an active collaboration between all stakeholders.

     

Seabird bycatch vulnerability to pelagic longline fisheries: Ecological traits matter

1. Fisheries bycatch of seabirds presents a serious management problem, and relatively little is known about this problem. In the Western North Atlantic, the issue is complicated by the relatively low effort and coverage of the observer programme and the high uncertainty in species identification.
2. The Western North Atlantic is home to many endemic and endangered seabird populations, and the impact of fishery‐caused seabird bycatch has been of high interest, especially for those species with a low population size; however, species‐specific bycatch estimates have been difficult. From 1992 to 2016, 158 seabirds were observed caught by the US Atlantic pelagic longline fleet; among them, only 80 were identified to species, 25 were identified to family, and the rest – mainly in the older records – were unidentified.
3. In this study, ecological traits of seabirds were used to improve bycatch estimation and provide species‐specific risk analysis to all the potentially affected seabird species in this region. Bayesian state–space modelling was used to accommodate the high level of uncertainty in the species identification process.
4. Seabird bycatch risk was found to be highly dependent on population size. The group of large seabird species was estimated to be two times as vulnerable as the group of mid‐to‐small seabird species, scavenging and plunge‐diving feeding modes were identified as imposing high bycatch risks, and spatial and temporal distribution patterns were also good indicators of bycatch risk. Based on these ecological traits, shearwaters, gulls, gannets, and petrels were identified to potentially suffer from high bycatch in this region. These species, especially those that have not been identified historically, deserve extra attention in the observer programme, and for the implementation of conservation measures of seabirds in this region.

     

Setting the net lower: A potential low-cost mitigation method to reduce cetacean bycatch in drift gillnet fisheries

1. Bycatch is the most significant threat to marine megafauna (sea turtles, marine mammals, elasmobranchs, seabirds) worldwide, and the leading cause of the decline of several cetacean species. The bycatch issue in the Indian Ocean is poorly understood, but high bycatch levels in gillnet fisheries have been documented for the past two decades, in both small-scale and semi-industrial fisheries. Unfortunately, methods to reduce bycatch are often unavailable, financially non-viable or socially unacceptable to fishermen.
2. Using a network of trained boat captains in the tuna drift gillnet fishery in the Arabian Sea, targeted catch and bycatch data were collected from 2013 to 2017 off the coast of Pakistan (northern Indian Ocean). Two fishing methods using multifilament gillnets were used: surface deployment and subsurface deployment (i.e. headline of net set below 2 m depth).
3. Predicted catch rates for targeted species did not differ significantly between the two fishing practices, although a drop in tuna (6.2%) and tuna-like (10.9%) species captures was recorded in subsurface sets. The probability of cetacean bycatch, however, was 78.5% lower in subsurface than in surface sets.
4. Cetacean bycatch in tuna drift gillnet fisheries has the potential to be significantly reduced at a relatively low cost for fishers. However, further research with an appropriate sampling design and a large sample size is required to confirm the efficacy of the proposed mitigation method. The acceptability and adoption of subsurface setting by fishers also needs to be further investigated. Despite some limitations, this preliminary study also highlights the importance of crew-based observer data as an alternative source of data when observers cannot be deployed on fishing vessels.

     

Identifying female foraging ecotype and fisheries impacts through pup whisker stable isotopes

1. Individual specialization in the foraging behaviour of marine predators can affect the ecology, evolution, and ability of a population to respond to environmental variability and human impacts.
2. Here, blood serum and whisker stable isotope values from New Zealand (NZ) sea lion pups (Phocarctos hookeri) are compared with their mother’s values to identify whether they can be used as proxies to identify their mother’s isotopic niche and foraging strategy.
3. Female NZ sea lions have been identified, both through telemetry and stable isotope research of blood serum and whiskers, to have two distinct foraging ecotypes (mesopelagic or benthic), consistent across their adult life. Females who are mesopelagic foragers have higher overlap and a greater risk of harmful interactions with fisheries.
4. Stable isotope analysis of adult females can be used to determine the proportion of the female population exposed to these detrimental interactions. However, the capture, restraint, and removal of a whisker or blood from an adult female NZ sea lion is an expensive, time-consuming, and invasive undertaking. Instead, by comparing the blood serum and whisker δ¹³C and δ¹⁵N values of 12 NZ sea lion mother-and-pup pairs, for whom the foraging behaviour of the female is known, the question as to whether a pup’s blood serum or whisker isotope value can be used as a proxy to identify female foraging ecotype was investigated.
5. The δ¹³C and δ¹⁵N values for the blood serum and whiskers of pups and their mothers were correlated and differed significantly between foraging ecotypes. This research validates that pup blood serum and whisker stable isotope values from 1-month-old pups can be used as indicators of female isotopic niche and therefore foraging ecotype.
6. This tool can be used across all NZ sea lion colonies to indicate female NZ sea lion foraging ecotypes. For the Auckland Islands, it could determine the proportion of breeding females exposed to negative interactions with fisheries, leading to a better understanding of the level of these effects and helping to implement appropriate management to mitigate impacts.

     

Incidental capture and mortality of sea turtles in the industrial double‐rig‐bottom trawl fishery in south‐eastern Brazil

1. Incidental capture by fisheries is one of the principal threats to sea turtles. This study analysed spatial and temporal patterns of sea turtle bycatch, and estimated the direct initial mortality rate of these animals, in the industrial double‐rig‐bottom trawl fishery in south‐eastern Brazil. This is also the first attempt to relate bycatch/at‐sea mortality in bottom trawling to stranded turtles found along the adjacent coast.
2. The fishery was monitored from October 2015 to April 2018 through data collected voluntarily by the captains of eight industrial double‐rig trawlers. Two hundred and one sea turtles were captured during 9362 tows (43,657.52 trawling hours), resulting in a catch per unit effort (CPUE) of 0.0025 ± 0.0032 turtles h^?1 with a standard net of 30.5 m headrope, with no significant difference between the estimated CPUEs for licensed shrimp and demersal fish trawlers.
3. Caretta caretta (52.24%) and Lepidochelys olivacea (38.81%) were the most frequently captured species. According to Generalized Linear Models, C. caretta bycatch was significantly higher during winter, at lower latitudes (?24° to ?23°) and higher longitudes (?42° to ?40°), while the L. olivacea bycatch was significantly higher at higher latitudes (?23° to ?21°). The direct initial mortality rate of sea turtles in the shrimp trawlers was 7.65 ± 3.85%. However, none of the dead individuals subsequently released with plastic tags (n = 10) were found stranded on the coast. Mortality was not significantly related to the depth or duration of the trawling.
4. The results of this study suggest the need for improvements to the current management of the bottom trawl fishery in Brazil, moving from a species‐based to a spatial and seasonal‐based approach. There is also a need to develop turtle excluder devices adapted to local fishing conditions.

     

Delineating foraging grounds of a loggerhead turtle population through satellite tracking of juveniles

1. Tracking of juvenile sea turtles is a research priority to inform the protection of relevant habitats and ensure sustainable rates of recruitment into adult populations. Based on satellite tracking, mixed stock analysis, and mark–recapture studies, Drini Bay in the South Adriatic Sea, Central Mediterranean, has been confirmed as an important foraging site used by loggerhead turtles from all major rookeries in the Mediterranean subpopulation.
2. Three juvenile loggerhead turtles (Caretta caretta) from Drini Bay were tracked for 763, 364, and 211 days respectively. All turtles exhibited different movement patterns.
3. The two smaller turtles ranged widely beyond the bay. One of these (69.5 cm curved‐carapace length; CCL) used the coldest region of the Mediterranean during the first winter of tracking where mean weekly temperatures dipped below 12°C but moved southwards to warmer waters during the second winter. In comparison, the other (66 cm CCL) individual moved south to winter in warmer waters from the outset. Both individuals returned to Drini Bay during summer, demonstrating fidelity to the study site. The third turtle, which was larger (76 cm CCL), remained in Drini Bay for the duration of tracking. These results support the findings of other mark–recapture studies at Drini Bay, which have suggested that the foraging site is being used in a transient way by immature turtles.
4. All three turtles preferentially used the shallow waters (<30 m) in the south of Drini Bay. The study demonstrates a high degree of overlap between the habitat use of the three tracked turtles and that of adult turtles tracked from nesting sites, and although based on a small sample size, contributes to a growing knowledge base regarding the wider habitat use of the Mediterranean loggerhead population.

     

A closer look at the bycatch of medium-sized and large sharks in the northern Catalan coast (north-western Mediterranean Sea): Evidence of an ongoing decline?

1. Historically, the Mediterranean Sea supported a rich shark fauna. Presently, however, populations of most shark species have significantly declined, largely due to intense fishing pressure.
2. Interviews with crew members of bottom trawlers, drifting longliners and bottom longliners operating off the Costa Brava (Catalonia, NE Spain) were conducted between October 2016 and July 2017 in order to gather information on the current bycatch rate of several shark species.
3. Interviews covered 41.2% of the fleet and respondents were asked for the bycatch of selected shark species—Alopias vulpinus, Cetorhinus maximus, Galeorhinus galeus, Hexanchus griseus, Isurus oxyrinchus, Mustelus spp., Prionace glauca, and Squalus acanthias—in two distinct time periods.
4. Bottom trawlers captured the highest diversity of species (eight) followed by bottom longliners (seven), and drifting longliners (three). Most respondents (89.7%) declared having captured at least one shark from 2006 to 2016 but only 56.4% declared having captured at least one shark from 2016 to 2017.
5. From 2016 to 2017, the whole fleet captured 89 specimens of H. griseus (95% confidence interval (CI) = 145, 34), 14 of G. galeus (95% CI = 30, 0), 3 of A. vulpinus (95% CI = 8, 0), 3 of I. oxyrinchus (95% CI = 8, 0), 3 of C. maximus (95% CI = 6, 0), and no Mustelus spp. The total bycatch of P. glauca and S. acanthias was uncertain due to extremely loose confidence intervals.
6. A significant decline was perceived by fishermen in the bycatch of C. maximus and S. acanthias, whereas the bycatch of H. griseus was considered to have remained stable.
7. This study suggests a dramatic reduction in the abundance of most of the medium-sized and large sharks of the Costa Brava and the likely disappearance of Mustelus spp. from the area. Only H. griseus, S. acanthias, and P. glauca are still being bycaught frequently.

     

Connectivity between lentic and lotic freshwater habitats identified as a conservation priority for coho salmon

1. Juvenile Pacific salmon exhibit diverse habitat use and migration strategies to navigate high environmental variability and predation risk during freshwater residency. Increasingly, urbanization and climate-driven hydrological alterations are affecting the availability and quality of aquatic habitats in salmon catchments. Thus, conservation of freshwater habitat integrity has emerged as an important challenge in supporting salmon life-history diversity as a buffer against continuing ecosystem changes.
2. To inform catchment management for salmon, information on the distribution and movement dynamics of juvenile fish throughout the annual seasonal cycle is needed. A number of studies have assessed the ecology of juvenile coho salmon (Oncorhynchus kisutch) during summer and autumn seasons; catchment use by this species throughout the annual cycle is less well characterized, particularly in high-latitude systems.
3. Here, n = 3,792 tagged juvenile coho salmon were tracked throughout two complete annual cycles to assess basin-wide distribution and movement behaviour of this species in a subarctic, ice-bearing catchment.
4. Juvenile coho salmon in the Big Lake basin, Alaska, exhibited multiple habitat use and movement strategies across seasons; however, summer rearing in lotic mainstem environments followed by migration to lentic overwinter habitats was identified as a prominent behaviour, with two-thirds of tracked fish migrating en masse to concentrate in a small subset of upper catchment lakes for the winter. In contrast, the most significant tributary overwintering site (8% of tracked fish) occurred below a culvert and dam, blocking juvenile fish passage to a headwater lake, indicating that these fish may have been restricted from reaching preferred lentic overwinter habitats.
5. These findings emphasize the importance of maintaining aquatic connectivity to lentic habitats as a conservation priority for coho salmon during freshwater residency.

     

Freshwater turtle bycatch research supports science‐based fisheries management

1. Although it is sometimes difficult for researchers to ensure that their work is used by resource managers to make informed decisions, an example where this knowledge–action gap has been breached is in research published in Aquatic Conservation: Marine and Freshwater Ecosystems (AQC) – among other journals – that has assisted fisheries managers in identifying strategies for reducing freshwater turtle bycatch in commercial hoop net fisheries in Ontario, Canada.
2. Research published in AQC has provided evidence towards a simple and effective method for preventing turtle bycatch mortality in hoop nets, which could be adopted by the fishers. Other research published in AQC evaluated the effect of bycatch mortality on the probability of persistence of turtle populations with population viability analyses, and outlined the need to minimize bycatch mortality to prevent local extirpation. Nine other papers have been published on freshwater turtle bycatch in Ontario, furthering our knowledge on this issue including seasonality and temperature effects on catches, other net modifications, post‐release effects and assisted recovery, and the perspectives of fishers.
3. The research results were presented to local resource managers with further discussions involving industry and stakeholders to minimize turtle bycatch mortality. Over several years, researchers have provided information to resource managers; however, when an incident of high turtle mortality caught the public eye, the research was readily available and changes in regulations were quick to occur.
4. Reasonably good communication among researchers, resource managers, industry, stakeholders, and the broader public allowed the rapid implementation of regulations to mitigate freshwater turtle bycatch mortality and bridged the knowledge–action gap between researchers and resource managers.
5. Both articles published in AQC had practical conservation impacts and were influential in providing local resource managers with feasible solutions, and the impetus to change regulations. These impacts extended to other jurisdictions and their monitoring programmes, where methods to reduce turtle bycatch mortality were also implemented.

     

Seasonal encounter rate,life stages and main threats to the loggerhead sea turtle (Caretta caretta) in the Aeolian Archipelago (southern Thyrrenian Sea)

1. Annual and seasonal encounter rates, life stages and the main threats to loggerhead sea turtles (Caretta caretta) in the Aeolian Archipelago (southern Italy) were studied.
2. Dedicated boat surveys resulted in 258 surface observations and 138 captures of healthy (n = 309), ailing (n = 66) and dead (n = 21) turtles from 2009 to 2013.
3. Loggerheads were encountered at the sea water surface while resting (87%) or feeding on pelagic prey (13%).
4. The loggerhead encounter rate (observations per km surveyed) was higher during the autumn, suggesting the presence of potential foraging/overwintering habitats in the area.
5. The mean (± SD) curved carapace length (CCL) was 48.8 ± 10.7 cm, with 65% of the individuals ranging from 40–70 cm in size. Smaller turtles were encountered more frequently during the spring months, probably as a result of the abundant pelagic prey within the coastal area. During the colder season, larger turtles were more common in the afternoon than in the morning, suggesting that the time needed for rewarming might increase with turtle size.
6. Ingestion of anthropogenic debris was reported in 48.5% of the rescued turtles. Individual mortality was mainly related to longline fishing (70.6%), with debris entanglements/ingestion frequently associated with these records. Longline bycatch and boat collisions were higher in summer, whereas debris ingestion was highest in spring. Different threats might affect particular life stages because the longline bycatch was more frequent for larger turtles, whereas boat collisions were more frequent with smaller individuals.
7. Migratory patterns, habitat characteristics and seasonal changes in sea temperature and currents might influence the seasonal occurrence of loggerhead turtles in this area.
8. These results increase the current ecological knowledge of the factors driving loggerhead turtle life and are important for implementing management plans for its conservation in the Mediterranean Sea.

     

The surface behaviour of white sharks during ecotourism: A baseline for monitoring this threatened species around Guadalupe Island,Mexico

1. 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.
2. 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.
3. 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).
4. 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.
5. 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.
6. 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.
7. 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.
8. 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.

     

Fisheries induced shift in sea snake community assemblages along the Konkan coast,India

1. The impacts of fisheries on several charismatic marine fauna have been a subject of global concern. Sea snakes share the same habitats as many commercially important fish species and often end up as fisheries bycatch.
2. Previous studies of bycatch from India have been limited to individual reports of mortality, with little information on the regional community structure of sea snakes. This study was carried out along the Konkan coast, off the central west coast of India, between 2016 and 2018, to determine trends in the bycatch of sea snakes in coastal fisheries.
3. In this study, 922 sea snakes were encountered in 916.57 gillnet haul hours and 449.16 trawlers haul hours of fishing, comprising largely of two species: beaked sea snake (Hydrophis schistosus) and spine-bellied sea snake (Hydrophis curtus) (83.05 and 16.94% respectively) which was in stark contrast to a similar study conducted in 2002–03, which recorded a dominance of H. curtus (84%) followed by H. schistosus (14%) in the same region. Both studies, however, indicated higher mortality in H. curtus than in H. schistosus in trawl nets.
4. This study highlights the significant impact of non-selective fishing practices on regional assemblages of other marine organisms such as sea snakes from South Asia, which has been relatively understudied, and the potential consequences for local ecosystems.

     

High mortality of adult female Magellanic penguins by gillnet fisheries in southern Brazil

1. Bycatch in gillnet fisheries is one of the main threats to several penguin species. Magellanic penguins (Spheniscus magellanicus) are caught by gillnets during their wintering in southern Brazil. However, current information is based only on a small number of sets observed during a single fishing trip.
2. This study assesses bycatch rates of bottom and drift gillnets operating in southern Brazil, and describes the sex and age classes of individuals captured.
3. In 80 bottom gillnet sets, 33 penguins were captured (85% adults), 14 were sexed of which 13 were females. In 41 drift gillnet sets, four penguins were captured, three of which were juveniles.
4. The mean bycatch rates, measured as number of penguins km^?2 of net and number of penguins km^?2 h^?1, were significantly higher for the drift gillnets.
5. Despite the lower bycatch rates, owing to the higher fishing effort in terms of number of boats, net length, net area, soak time and fishing season, the magnitude of penguin bycatch in the bottom gillnet fishery cannot be ignored.
6. Despite based on small sample size, the predominance of adult and female Magellanic penguins as bycatch in gillnet fisheries in southern Brazil agrees with previous studies suggesting that females displace further north than males. In addition, such evidence contributes to the male‐biased sex ratio in breeding grounds, and the long‐term decline of major Patagonian colonies owing to higher female mortality during winter.