Nursery habitat for Asian horseshoe crabs along the northern Beibu Gulf,China: Implications for conservation management under baseline gaps

1. Identification, protection and enhancement of essential habitats are priority issues for management and restoration of exploited species. The shores utilized by Asian horseshoe crabs as nurseries were surveyed and the coastal habitat characteristics were described in the northern Beibu Gulf of China. Regression models were applied to explore species‐habitat relationships.
2. Fourteen and ten nursery sites were identified for Tachypleus tridentatus and Carcinoscorpius rotundicauda populations, respectively. Xiacun and Jinhaiwan in the eastern region of the northern Beibu Gulf were the essential nurseries for T. tridentatus, whereas Shanxin and Jiaodong in the western part were the primary nursery shores for C. rotundicauda. These shores supported high densities (4–6 individuals/100 m²) of juvenile horseshoe crab populations.
3. Mangrove and seagrass coverage area, coupled with sediment physico‐chemical parameters, particularly grain size, and the environmental heterogeneity of nursery habitats explained the distribution pattern of juvenile populations. Most juvenile populations were found along the outer fringe of mangroves in the small shallow estuary, particularly near outflows of tidal creeks with generally higher chlorophyll a and organic carbon contents. The distribution of high‐density juvenile populations of both species also overlapped with areas of seagrass patches.
4. These findings highlight the importance of mangroves and seagrasses in the nursery habitat use of Asian horseshoe crabs. Preserving the estuarine habitats with these vegetation types and identifying the high‐use nursery sites should be prioritised in China and other Asian places to conserve the declining Asian horseshoe crab populations.

     

Morphological Traits of Wild and Selected Strains of Cultured Undaria pinnatifida from Galicia (NW Spain)

Wakame, Undaria pinnatifida, is one of the most popular seaweeds used for human consumption in the world. Wakame quality is mainly valued on the basis of its morphological features. Continual inbreeding and directional selection have traditionally been used with economic seaweeds to obtain elite strains with high‐quality forms. In this study, we compared the morphological traits of cultured sporophytes originating from wild and selected strains of U. pinnatifida in Galicia (NW Spain). Seedlings (young sporophytes) of the two strains were cultured at a sheltered site in a coastal bay of Galicia under the same environmental conditions. Sixteen different morphological measurements were taken on cultured sporophytes. We found that the sporophytes of both wild and selected strains were significantly similar in all studied morphological characters. These results suggest that the morphology of cultured strains of U. pinnatifida from Galicia is due to environmental conditions and that specific morphological traits are dependent on the cultivation environment. Consequently, the morphological traits of Galician U. pinnatifida populations are not an important factor in selective breeding for enhanced wakame quality, and hence, for the establishment of a germplasm bank (e.g., gametophyte stocks).     

Carotenoid Profile of Edible Japanese Seaweeds: An Improved HPLC Method for Separation of Major Carotenoids

An improved multi-step gradient reverse phase high performance liquid chromatography (HPLC) method to simultaneously separate major carotenoids from natural as well as food samples was developed. Quantitative profiling of carotenoid compounds was carried out on three edible brown seaweeds (Sargassum horneri, Cystoseira hakodatensis, and Undaria pinnatifida) and three red seaweeds (Gracilaria vermiculophylla, Grateloupia asiatica, and Grateloupia livida). Fucoxanthin (Fx) was detected in all the brown seaweeds with quantities (mg g^?1 dry weight [dwt]) ranging from 1.3 ± 0.3 in C. hakodatensis to 2.4 ± 0.1 in S. horneri. U. pinnatifida, commonly known as wakame, had a Fx content of 2.3 ± 0.1 mg g^?1 dwt. In the case of red seaweeds, zeaxanthin (Zx) was the major carotenoid, and G. vermiculophylla had the highest Zx content (80.2 μg g^?1 dwt) among the red seaweeds apart from small amounts of Fx (9.1 μg g^?1 dwt). Similarly, the other two species of red seaweeds, G. asiatica and G. livida, contained (μg g^?1 dwt) lutein (Lut), Fx, and Zx as the major carotenoids (G. asiatica: Lut 10.4, Fx 1.5, Zx 1.1; G. livida: Lut 9.3, Fx 3.5, Zx 1.0). The results suggest the usefulness of edible varieties (barring wakame) of seaweeds as dietary sources of carotenoids.     

Novel insights into the marine phase and river fidelity of anadromous twaite shad Alosa fallax in the UK and Ireland

1. Most research on anadromous fishes has been invested in their freshwater life‐phases, resulting in a relatively sparse understanding of their spatial ecology during marine life‐phases. However, understanding the marine dispersal of anadromous fishes is essential to identify threats and to implement conservation measures that fully encompass their lifecycle.
2. The twaite shad Alosa fallax is an anadromous fish increasingly imperilled across its range due to pollution, harvesting, and impediments to freshwater migration, but little is known about its distribution and movements during its marine life‐phase. Here, the application of acoustic telemetry provided novel insights into the coastal dispersal of twaite shad in the UK and Ireland during 2018–2019, and the freshwater entry of individuals during the 2019 spawning season.
3. Of 73 twaite shad acoustic‐tagged during their upstream migration in the River Severn in May 2018, 58 emigrated from the river. Twelve were subsequently detected 200 km to the south‐west at the Taw–Torridge Estuary between July 2018 and April 2019, where estuarine movements up to 5.8 km inland occurred in summer, winter, and spring. One was subsequently detected in the Munster Blackwater Estuary (Ireland) and then in the River Severn, indicating a minimum movement distance of 950 km. Thirty‐four (59%) of the emigrating individuals from 2018 re‐entered fresh water in the rivers Severn (n = 33) and Wye (n = 2) in April and May 2019.
4. These results suggest year‐round use of estuarine and nearshore habitats by at least a subset of the twaite shad population during their marine phase, providing evidence of potential range overlap between populations that spawn in different areas in the UK and Ireland, which may be facilitated by substantial dispersal. The results also highlight the potential of telemetry for estimating freshwater and marine mortality, and the benefits of sharing detection data across networks.

     

Epiphytism on Blades of the Edible Kelps Undaria pinnatifida and Saccharina latissima Farmed under Different Abiotic Conditions

The kelps Undaria pinnatifida and Saccharina latissima are economically valuable edible seaweeds. Although epiphytism is a major problem affecting the productivity and quality of farmed seaweeds, studies of its effects on kelp aquaculture are scarce. We investigated the effects of epiphytism in two U. pinnatifida and S. latissima culture grounds located in two different parts (exposed and sheltered) of a bay (ría) in Galicia (NW Spain). Epiphytic organisms on blades were identified and their abundance was documented. The percentage of the total blade covered with epiphytes was measured for both kelp species in order to estimate the blade biomass that must be discarded during processing for human consumption. Algae, hydroids, and crustaceans were the most common epiphytic organism on kelp blades; colonies of the hydroid Obelia geniculata and harpacticoid copepods were the most abundant epiphytes. Abundance of epiphytes on the blades of both kelps was significantly higher for fronds growing in the sheltered area of the bay compared to those farmed at the exposed location. Different environmental conditions and other factors, such as the proximity of mussel cultures to kelp cultures, may be important contributors to epiphytism. The results presented here can be used to devise better ways for kelp aquaculture facilities to diminish the negative effects of epiphytism.     

Using low‐cost drones to monitor heterogeneous submerged seaweed habitats: A case study in the Azores

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Low genetic variation and isolation of northern peripheral populations of a red seaweed (Grateloupia lanceola)

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Adding large woody material into a headwater stream has immediate benefits for macroinvertebrate community structure and function

1. Hydromorphological rehabilitation through installing large woody material (LWM) is increasingly being used to reverse degradation of stream ecosystems. There have been many criticisms of stream rehabilitation projects, because many have not met their goals and many others have not been monitored well enough to assess whether their goals were met.
2. In a before–after–control design (with samples collected 1 year before and two successive years after LWM installation), instream biotopes and their macroinvertebrate assemblages were used as structural and functional units to assess the effectiveness of LWM installed at the Rolleston Brook, a headwater tributary of the River Welland in Leicestershire, UK.
3. The project was successful in enhancing the coefficient of variation of channel water depth and width, wetted surface area, number of instream biotopes, and the biotope diversity in the rehabilitated reach.
4. LWM installation led to significant increases in macroinvertebrate total density, total biomass, and taxon richness. Macroinvertebrate community composition was also enhanced, so that it became more similar to that of the control reach.
5. Small increases in the number of instream biotopes (appearance of gravel and leaf litter) and changes in biotope proportions (decreasing percentage of silt) were significantly related to changes in the macroinvertebrate community metrics in the rehabilitated reach.
6. The results show that using macroinvertebrate community composition is more effective than only using taxon richness and/or diversity metrics for understanding the relationship between LWM installation and macroinvertebrate community responses. To be effective, samples must also be collected in a predefined sampling protocol stratified at the instream biotope level. This approach would be of great benefit in evaluating biodiversity conservation value, and could be incorporated into the advice provided by Natural England concerning restoration and protection of English rivers that are designated as Sites of Special Scientific Interest under UK legislation or Special Areas of Conservation under European legislation.

     

Population abundance and habitat preference of the Yangtze finless porpoise in the highest density section of the Yangtze River

1. Habitat loss and degradation together represent one of the five major factors contributing to the rapid decline of the Yangtze finless porpoise in the Yangtze River. Protecting key habitat patches and maintaining migration corridors between habitat patches are major conservation objectives to ensure the in situ viability of the Yangtze finless porpoise. Baseline information essential for addressing these two objectives includes that pertaining to distribution and habitat preference.
2. To investigate the distribution and habitat preferences of the Yangtze finless porpoise, five transect surveys were conducted in the Anqing section of the Yangtze River, which has the highest porpoise density among all sections of the river. Porpoise abundance estimates were calculated, and preferences for different habitat types were evaluated.
3. The calculated porpoise abundance in the Anqing section was 181 (95% CI 125–239) animals on average. The inter‐annual and inter‐seasonal differences in porpoise abundance estimates were not significant. The natural river banks and sandbar shores were the most preferred habitats, representing 46.3 and 29.8% of the porpoise observations, respectively. In contrast, 8.1% of the porpoises were observed in habitats along reinforced river banks, which account for 38.7% of the total coastline. In subsections with natural habitat patches, porpoises were observed in almost every survey, while porpoise occurrence became highly stochastic in subsections with long reinforced river banks. These results indicate a significant tendency of the Yangtze finless porpoise to prefer natural habitats with natural river bank or sandbars but to keep away from reinforced river‐bank habitats.
4. According to porpoise density in different subsections, free migration may be impeded or only one migration corridor remains in some subsections.
5. Although protecting finless porpoise habitats has become a primary conservation objective, this study highlights the need to protect frequently used habitat patches and migration corridors, particularly those near natural river banks and sandbars, and to restore ecological environments along reinforced river banks.

     

Patterns and impacts of fish bycatch in a scallop dredge fishery

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Can drifting objects drive the movements of a vulnerable pelagic shark?

1. Juvenile silky sharks (Carcharhinus falciformis) regularly associate with floating objects yet the reasons driving this behaviour remain uncertain. Understanding the proportion of time that silky sharks spend associated with floating objects is essential for assessing the impacts of the extensive use of fish aggregating devices (FADs) in the tropical tuna purse-seine fisheries, including increased probability of incidental capture and the potential of an ecological trap.
2. Previous studies provided insight into the amount of time that silky sharks spent at an individual FAD but were unable to assess neither the time spent between two associations nor the proportion of time spent associated/unassociated.
3. The percentage of time that juvenile silky sharks spend unassociated with floating objects was estimated through the analysis of horizontal movements of 26 silky sharks monitored with pop-up archival tags. Under the assumption that a high association rate with drifting FADs would align the trajectories of tracked sharks with ocean surface currents, a novel methodology is proposed, based on the comparison of shark trajectories with simulated trajectories of passively drifting particles derived using a Lagrangian model.
4. Results revealed that silky shark trajectories were divergent from surface currents, and thus unassociated with FADs, for at least 30% of their time. The potential of the methodology and the results are discussed in the context of increasing FAD densities in the Indian Ocean.

     

Evaluating the distribution of priority benthic habitats through a remotely operated vehicle to support conservation measures off Linosa Island (Sicily Channel,Mediterranean Sea)

1. Explorations of the Mediterranean deep sea using remotely operated vehicles have shown that the sea bed hosts rich habitats, supporting high biodiversity. However, there have been only a few studies dealing with the southern part of the basin, leading to limited protection and conservation efforts in this area.
2. This study aimed to explore the sea bed off Linosa Island (Sicily Channel, southern Mediterranean Sea), which is considered a ‘sentinel area’ for alien species and global environmental changes owing to its geographic position, thus deserving special attention.
3. Remotely operated vehicle surveys, carried out in 2016 and 2017, were analysed to provide the first ecological characterization of benthic assemblages at depths −19 – −384 m around Linosa Island.
4. Communities were dominated by three priority habitats, amounting to 39% of the almost 5 km of the sea floor that was surveyed. These are represented in the euphotic zone by Posidonia oceanica meadows and, at greater depth, by newly discovered dense coral forests and extended rhodolith/maërl beds. Sixteen habitat-forming species included in the Red List of the International Union for Conservation of Nature (e.g. gorgonians Eunicella cavolini and Paramuricea clavata, and black corals Antipathella subpinnata and Leiopathes glaberrima) were recorded, as well as individuals of Sargassum sp. at −100 m depth.
5. The volcanic island of Linosa represents a small, naturally preserved area, with very limited human pressure, hosting rich marine benthic biodiversity. Given the high species and habitat richness, we recommend its inclusion in the Special Protected Areas of Mediterranean Importance project (United Nations Environment Programme) and suggest a redefinition of the existing marine protected area extension.

     

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.

     

Sun coral management effectiveness in a wildlife refuge from south-eastern Brazil

1. The introduction of exotic species is one of the major causes for biodiversity loss in marine environments. Introduced species can change habitat complexity, impacting local communities and altering ecosystem functioning.
2. Since the 1980s, the scleractinian species Tubastraea coccinea and Tubastraea. tagusensis (commonly known as sun corals) have been spreading in the south-western Atlantic, posing a major threat to local biodiversity and marine ecosystems. Nowadays, these species are reported from more than 3,500 km along the Brazilian coast and on at least 21 oil and gas offshore platforms.
3. Considering the great environmental pressure resulting from sun coral invasion, this study verified the effectiveness of manual removal of Tubastraea spp. along a rocky shore in Alcatrazes Wildlife Refuge, one of the most pristine marine regions in Brazil.
4. Results indicate that removal is indeed effective as a control technique; however, as invaders have high regeneration capabilities and recruitment rates, successive management efforts are essential. In order for management to be effective against Tubastraea's year-round release of clonal larvae, results suggest invaded areas should receive at least two management actions per year.
5. Successive management efforts, in addition to the development of new techniques and prevention of new invasions should be priorities for mitigating sun coral impacts.

     

Scarring patterns of whale sharks,Rhincodon typus,at a provisioning site in the Philippines

1. Shark-based tourism continues to be a rapidly growing industry, and thus understanding the impacts of such activities is essential to mitigate the potential negative effects on the target species. The consequences of provisioning on whale sharks (Rhincodon typus) are not fully understood, although changes to the local environment, ecology, behaviour, and site visitation patterns have been highlighted. Here, the scarring patterns of whale sharks were investigated at a provisioning site in Oslob, Cebu, Philippines, as an indicator of the physical impacts of tourism activities on individual sharks. Photographic identification was used to attribute scars to individual animals (n = 152) between March 31, 2012 and January 31, 2015.
2. Scars were categorized by type and body location, and were compared with non-provisioned aggregations in Australia, Mozambique, and Seychelles. Oslob whale sharks were more scarred than other studied populations, with 94.7% (n = 144) having at least one scar, and with 90.8% (n = 138) having more than one scar. Scarring incidence was found to be significantly higher in sharks that regularly visited the provisioning site, and analysis of scarring over time in highly resident sharks showed that all individuals gained scars through periods of consistent re-sightings. A significantly higher incidence of minor scar types was found, most commonly on the dorsal side of the animal, probably resulting from sustained proximity to boats and ropes throughout the provisioning activities. The consequences of interactions with propeller boats were observed, despite a ban on their use in the provisioning site, highlighting the risk to the species beyond the study site.
3. We recommend the strict enforcement of a minimum distance between boats and sharks, a zero-contact policy during interactions, the expansion of the provisioning site, and the implementation of a no-boat-access zone around the perimeter of the provisioning site to mitigate potential collisions.

     

You cannot conserve a species that has not been found: The case of the marine sponge Axinella polypoides in Liguria,Italy

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

     

Hydromorphological rehabilitation improves channel morphology,instream biotopes,and macroinvertebrate communities,and thus enhances the conservation of an urban river

1. Many river rehabilitation projects have been criticized for failing to meet their goals or for being insufficiently monitored. There is, therefore, an urgent need to develop robust approaches for assessing treatment efficacy and thus guide the increasing investment in rehabilitation.
2. Instream biotopes (formerly called ‘functional habitats’ or ‘mesohabitats’ by different authors) and their macroinvertebrate assemblages were used to assess the effectiveness of entire-channel hydromorphological rehabilitation of a 1.8-km stretch of a lowland stream through the town of Market Harborough, Leicestershire, UK.
3. The project successfully enhanced the physical diversity, measured in the rehabilitated reach as the coefficients of variability for channel water depth and width, wet surface area, number of instream biotopes, and biotope diversity.
4. The project also enhanced the biodiversity conservation value, measured as macroinvertebrate total density, total biomass, richness, diversity, Ephemeroptera, Plecoptera, and Trichoptera (EPT) richness, EPT diversity, EPT count%, and EPT biomass%, all of which significantly increased following rehabilitation. Chironomidae count% and biomass% significantly decreased following rehabilitation. Rehabilitation was also successful in significantly increasing macroinvertebrate shredder, scraper, and filter-feeder group density.
5. Changes in the macroinvertebrate community metrics in the rehabilitated reach were related significantly to changes in the percentages of cover of instream biotopes and increases in biotope diversity in the rehabilitated reach.
6. Macroinvertebrate structural and functional metrics can provide quantitative data for assessing reach-level rehabilitation outcomes, if samples are collected in a pre-defined sampling protocol stratified at the instream biotope level.
7. The practical implications of this work are that the design of rehabilitation projects, if based upon the recreation of biotope heterogeneity, will succeed in improving biological value and restoring the area to near naturalness if a suitable upstream source of macroinvertebrates for natural recolonization is available. The study shows that the concept of biotopes has an important role to play in river conservation management.

     

Conservation status assessment and a new method for establishing conservation priorities for freshwater mussels (Bivalvia: Unionida) in the middle and lower reaches of the Yangtze River drainage

1. The freshwater mussel (Unionida) fauna of the Yangtze River is among the most diverse on Earth. In recent decades, human activities have caused habitat degradation in the river, and previous studies estimated that up to 80% of the mussel species in the Yangtze River are Threatened or Near Threatened with extinction. However, a comprehensive and systematic evaluation of the conservation status of this fauna has yet to be completed.
2. This study evaluated the conservation status of the 69 recognized freshwater mussel species in the middle and lower reaches of the Yangtze River, using the criteria published by the International Union for Conservation of Nature (IUCN). A new method for prioritizing species for conservation was then developed and applied termed Quantitative Assessment of Species for Conservation Prioritization (QASCP), which prioritizes species according to quantifiable data on their distribution and population status, life history, and recovery importance and potential.
3. IUCN assessments showed that 35 (51%) species in the study region are Threatened or Near Threatened (11 Endangered, 20 Vulnerable, 4 Near Threatened). In addition, 16 species (23%) could not be assessed owing to data deficiency. Key threats to the freshwater mussel biodiversity of the Yangtze River include pollution, habitat loss and fragmentation, loss of access to host fish, and overharvesting of mussels and their host fish. The genera Aculamprotula, Gibbosula, Lamprotula, Pseudodon, Ptychorhynchus, and Solenaia were identified as particularly threatened.
4. Data availability allowed QASCP assessment of 44 species. Only Solenaia carinata, regionally Endangered under IUCN criteria, achieved the highest QASCP rank, i.e. First Priority. The five species assessed as Second Priority were considered either regionally Endangered (one), Vulnerable (three), or Data Deficient (one) under IUCN criteria. The 23 Third Priority species were assessed as regionally Endangered (two), Vulnerable (15), Near Threatened (two), or Least Concern (four).

     

Abundance estimates of three cetacean species in the coastal waters of Matang,Perak, Peninsular Malaysia

1. The paucity of baseline data on coastal cetaceans due to a lack of research in developing countries frequently precludes assessment of their status and informed management actions for conservation.
2. This study provides the first abundance estimates of Indo-Pacific humpback dolphins, Irrawaddy dolphins, and Indo-Pacific finless porpoises in the coastal waters of Matang, Peninsular Malaysia.
3. Boat-based surveys covering 1,152 km² of coastal waters with 4,108 km of survey effort were conducted between 2013 and 2016 to collect data for line transect analysis of Irrawaddy dolphins and finless porpoises. Photo-identification data of humpback dolphins were concurrently collected for mark–recapture analysis.
4. Estimates of abundance from four sampling strata totalled 763 Irrawaddy dolphins (CV = 13%, 95% confidence interval (CI) [588, 990]) and 600 Indo-Pacific finless porpoises (CV = 27%, 95% CI [354, 1,016]).
5. The annual abundance estimates of humpback dolphins ranged between 171 (95% CI [148, 208]) in 2014–2015 and 81 (95% CI [67, 98]) in 2015–2016, likely due to the presence of offshore individuals that moved in and out of the study area. The estuarine strata were inhabited by 68 (95% CI [63, 73]) inshore humpback dolphins in 2013–2014 to 87 (95% CI [78, 97]) dolphins in 2014–2015.
6. As an International Union for Conservation of Nature important marine mammal area, the productive coastal waters of Matang are shown to support a high density of small coastal cetaceans, and the results serve as an important baseline for future studies to identify population trends for conservation management plans.

     

Fisheries and conservation assessment of sharks in Pacific Panama

1. In Panama, shark fisheries were initially developed in the 1980s and progressively increased in production in the 1990s mainly due to the high demand for shark fins and meat from the international Asian market. Since then, and despite the exploitation rate (average 3,514 t year^–1) and endangered status of some species, shark fisheries have seldom been studied, and official statistics are general or incomplete and not suitable for the development of appropriate conservation and management strategies.
2. To understand the dynamics of shark fisheries in Panama, field surveys were conducted between 2007 and 2009 at several landing ports of small‐scale and industrial fisheries, at fish processing plants and on‐board fishing vessels in Pacific Panama, where most of the fishing vessels of the country operate.
3. In general, it was found that the artisanal and industrial fisheries of the Pacific coast of Panama regularly exploit at least 18 species of sharks, which are also being exploited by neighbouring countries in the eastern Pacific, suggesting the importance of coordinated conservation initiatives across the multiple jurisdictions. A large number of the individuals caught were immature, implying a certain level of impact on recruitment rates. This pattern was particularly evident in species such as Sphyrna lewini, for which immature individuals represented at least 99% and 63% of the total catch by small‐scale and industrial fisheries, respectively. Catch per unit of effort analyses showed that Carcharhinus and Sphyrna species were the most exploited (representing ~80% of the catches) by industrial fisheries in Panama between 2006 and 2009, suggesting that fishery management should provide special attention to these groups.
4. It is expected that the information presented here provides a baseline to develop new regulations, including the implementation of annual quotas and fishing seasons and the protection of nursery areas, for the long‐term sustainability and conservation of sharks in Panama.