Fishing Research Articles

Spatial distribution of the sport fishing in the state of Amazonas, northern Brazil.

The objective of this study was to spatialize sport fishing operations and assess the frequency of the use of the fishing areas in the state of Amazonas by combining the Geographic Information System (GIS) approach and information available in the documents sent to the Instituto de Proteção Ambiental do Amazonas (IPAAM). Information on sport fishing tourism operations was gathered from the IPAAM database and fishing licenses (FLs). Data analysis was conducted utilizing descriptive analysis, and the spatialization of the locations was performed using Q-GIS software. From 2002 to August 2021, 163 requests for FLs were made. There was a decrease in the amount of first time FL requests, with a peak in 2018 and 2019, N=17 and N=18, respectively. The activity is conducted in 24 municipalities, with Barcelos (31.36%) and Presidente Figueiredo (17.75%) being the most popular. At the sub-basin level, sport fishing is notably present in the Negro, Amazonas, Aripuanã, Madeira, Purus and Solimões River basins. Overall, 26.38% of operations take place in conservation areas, specifically in sustainable development reserves (SDRs). Barcelos recorded the largest number of rivers used, with 15 rivers. These results can support future proposals for the sustainable management of fisheries through the zoning of fishing areas in the state of Amazonas.

Saving Walker Lake: A Pleistocene Terminal Lake in the Anthropocene

Abstract: Just to the east of the Sierra Nevada mountain range a series of Pleistocene terminal lakes are present in the Great Basin of the intermountain West between the Rockies and the Sierra. Among them is Walker Lake, fed by the branches of the Walker River that flow eastward from their snow-melt sources in the Sierra. The terminal lakes have no natural outlets. Water is lost from the lakes' surfaces by evaporation during the hot summer months in the high desert. Since the arrival of Euro-Americans in the nineteenth century, the diversion of water for agricultural, industrial, and domestic uses from the Walker River has reduced the level of the lake to a point where it no longer supports a once-thriving fishery of native cutthroat trout. In the past, western Nevada Paiute peoples relied on the lake's fish as a food source. In the twentieth century the inland anadromous trout drew sports fishing enthusiasts. Climate change has caused additional strains on the water supply for the lake to the point where many have declared Walker Lake a dead lake with only shrinking shorelines and increased salinization in its future. In response, Nevada's U.S. senator Harry Reid, members of the Walker River Indian Reservation, sport fishing organizations, as well as environmental organizations pushed for legislation from Congress to promote efforts to save the lake in the 1990s. These efforts have produced some promising results.

New records and range extension of two deep-sea skate genera,AmblyrajaandNotoraja(Elasmobranchii: Rajiformes), in the southeastern Pacific Ocean

AbstractTwo species of deep-sea skates,Amblyraja frerichsiandNotoraja martinezi, are reported for the first time in Peruvian waters, representing the first record of their respective genera from the country. Earlier,A.frerichsiwas known from both the southwestern Atlantic (off Brazil, Uruguay, and Argentina) and southeastern Pacific (off Chile), whileN.martineziwas known from Costa Rica to Ecuador in the eastern-central and southeastern Pacific. This study contributes to the limited knowledge of deep-sea fish diversity along the South American west coast, and stresses the need of further taxonomic research in the region, particularly in light of the ecological importance of this group of fishes in marine ecosystems and its conservation state worldwide.

Moorea lagoon fishers’ mental maps: An exploratory analysis of Polynesian spatial knowledge

AbstractThis empirical study builds upon prior research concerning cultural influences on spatial mental representations in Oceania. A comprehensive examination of 93 mental maps sourced from 59 lagoon fishers of Moorea (French Polynesia) reveals interesting facts about the way they organize and share their spatial knowledge. Firstly, consistent with previous studies across Oceania, Polynesian fishers exhibit a preference for the allocentric perspective when representing their environment. Secondly, they generally rely on marine landmarks for navigation, with a particular emphasis on four entities: the reef barrier, maritime beacons, coral outcrops, and a key chromatic marker — Moana (blue in Tahitian) — indicating the depth of the lagoon. Finally, the factor analysis we conducted highlights two significant facts: (1) a geographical self‐censorship, demonstrated by the low presence or even the absence of landmarks useful for locating their fishing spots; (2) a continuum between the surface and the depths of the lagoon, showing that surface fishers (line, net, troll, etc.) have a proven knowledge of seabed topography, whereas underwater speargun fishers also rely on landmarks located above the water.

Finding Nemo! Description of a New Species of Branchial Fish Parasitic Cymothoid, Elthusa Schioedte and Meinert, 1884 (Crustacea: Isopoda), infesting CallionymusfilamentosusValenciennes,1837 from the Northern Indian Ocean.

Specimens of Elthusa from trashfish of the Indian SW coast were described as a new parasitic cymothoid, Elthusa nemosp. nov., (Crustacea: Isopoda). Later, the branchial cavity of the Blotchfin dragonetCallionymus filamentosusValenciennes,1837 were documented as its micro- and macro-habitat (host). Fresh/live specimens of unidentified cymothoid samples were collected from the trash fishes obtained from Neendakara (08°30.0' N 76°53.30' E) fish landing centre, Kollam district, Kerala state, southwest coast of India. After a long search for the host species, we recovered the isopod from the branchial cavity of the deep-sea fish Callionymus filamentosus Valenciennes,1837 (Callionymiformes: Callionymidae). The new species is described and illustrated based on ovigerous females. Elthusa nemo sp. nov., has the following sets of combinations of characters: body slightly twisted, elongated, dorsal surfaces smooth, nearly twice as long as greatest width; pleon short, ~ 14% body length, 0.8 times as wide as pereon maximum width; widest at pleonite 2 and narrowest at pleonite 1; only pleonite 1, laterally overlapped by pereonite 7 posterolateral expansion and coxa 7; presence of appendix masculina on pleopod 2; uropods 0.8 times as the length of pleotelson; antenna with two plumose setae on article 4. Elthusa nemo sp. nov., is the sixth species of the genus known from Indian waters.

Impact of fishing ban on socioeconomic status of Hilsa fishers in Bangladesh

Fishing ban is a useful regulatory measure for sustainable management and conservation of hilsa shad (Tenualosailisha) in Bangladesh. This study investigated the socioeconomic status of hilsa fishers, as well as their perceptions regarding the performance of fishing bans and coping strategies. Data were collected from 300 fishers residing in the three study areas by using semi-structured questionnaire to collect data related to the livelihood and socioeconomic variables of the fishers. Besides, fishers’ perceptions regarding the performance of the ban as well as income generated from other activities during the fishing ban were also incorporated. Focus Group Discussions (FGD), Crosscheck Interviews (CI) with key informants’ interview was also conducted to collect general information and to justify the collected information. The majority of the fishers feel the bans have resulted in positive socioeconomic impacts which enhance their income and livelihood status from fishing. However, its impact on loss of income and level of unemployment during ban forced some fishers to drive away the ban. In contrast, diversified alternative livelihood options have been adopted by fishers to cope with the ban that not only pull them out from dependency solely on hilsa fishing but also reduce the fishing pressure on the hilsa fishery as well as fish biodiversity. The study showed a positive correlation between fishing ban and resources’ sustainability. In spite of the difficulties faced by fishers during ban, majority of the fishers support the ban for the long-term conservation of hilsa as it is their basic sustenance.

Length-weight relationship and morphometric and meristic variation in Dinnawah snowtrout, Schizothorax progastus, inhabiting the Suru River and its tributaries of Kargil, Ladakh Region

Abstract Morphometric variations across fish stocks have long been acknowledged as useful for determining population structure and identifying stocks. Schizothorax progastus (McClelland) is a common, dominant fish in most cold-water rivers and is considered a good sport fish and also delicious in taste. For the people of Ladakh, this fish is a significant source of nutrition. A total of 70 specimens were collected for this study. A total of 24 morphometric and six meristic characters were studied, with 18 morphometric characters assessed as percentages of total length and four characters analyzed as percentages of head length. Standard length and fork length had the strongest correlations with total length at 0.98 and 0.99, respectively. Overall, the findings demonstrated that all morphometric features had linear correlations and exhibited a high degree of association (P < 0.05). The meristic counts examined in this study were consistent among all fish of various sizes, suggesting that body size had no effect on them. The biological information generated from this study serves as an essential guideline for future management and conservation of S. progastus, an important food source in the Ladakh, Trans Himalayan region.

Fish otoliths from the bathyal Eocene Lillebælt Clay Formation of Denmark

Few deepwater otolith associations from the Eocene have been found so far. The small assemblage of aragonitic-preserved otoliths from the Lillebælt Clay Formation described here therefore adds to the understanding of early Palaeogene deep-sea fish faunas. These otoliths were obtained from a level at about the Ypresian/Lutetian interface and may thus be older than the otoliths previously described from Trelde Næs from mold casts from carbonate concretions. Only 14 otoliths were recovered from about 6,000 kg processed bulk samples. The assemblage also differs in the composition and contains three new species and one new genus: Diaphus? duplex n. sp., Bregmaceros danicus n. sp. and the ophidiid Pronobythites schnetleri n. gen, n. sp. In addition, the new genus Treldeichthys n. gen. in Acanthomorpha incertae sedis is established for T. madseni (Schwarzhans, 2007). The small assemblage also differs in composition from comparable associations described from southwest France and northern Italy on the species level but shows some relationship on a higher systematic level. The mechanism and timing of the colonization of the deep sea by selected groups of fishes is discussed, particularly in respect to the depth migration of demersal fishes.

The influence of freshwater inflow and seascape context on occurrence of juvenile spotted seatrout Cynoscion nebulosus across a temperate estuary.

Spotted seatrout, a popular recreational sport fish in the southeastern United States, are affected by freshwater flow conditions and the availability of estuarine habitat. However, the relative influence of these factors, particularly on early life stages of seatrout, remains uncertain. We used generalized linear models to quantify relationships between the probability of encountering juvenile spotted seatrout during seine surveys and various factors, including freshwater inflow conditions, the availability and richness of estuarine habitats (seagrass, salt marsh, oyster beds) around (400-m radius) fish collection sites (seascape-scale context), as well as distance to the nearest inlet to the Gulf of Mexico (estuary-scale context) across shallow waters (< 1.5 m depth) of Apalachicola Bay, Florida. Modelling results showed a consistent positive correlation between seagrass area and the probability of encountering juvenile seatrout (all four size classes from 15mm-200mm Standard Length (SL)). The probability of encountering the two smallest juvenile seatrout size classes (15-50mm and 51-100mm SL) was also related to freshwater inflow conditions, particularly within a 3-month period prior to and including peak recruitment. Freshwater inflow may affect early life stages by influencing passive transport of eggs and larvae, planktonic food availability, and predation pressure through increases in turbidity. In contrast, encounter probabilities of the two larger size classes (101-150mm and 151-200mm) were unrelated to freshwater inflow. Inflow-related processes may be less important to the larger juveniles as they have typically settled out of the plankton into benthic habitats which provide refuge from predation and abundant benthic food sources which are not as closely tied to freshwater inflow effects. In addition, models revealed that occurrence of the larger juveniles was related to the availability of nearby habitat types such as oyster beds and salt marshes, suggesting that increased mobility as seatrout grow may allow them to use nearby habitat types as additional sources of food and refuge. These results add to a growing body of literature aimed at understanding the influence of freshwater inflow as well as seascape context on vulnerable juvenile life stages of fishery species to provide more informed strategies for freshwater inflow management and habitat conservation.

Towards unlocking the trophic roles of rarely encountered squid: Opportunistic samples of Taningia danae and a Chiroteuthis aff. veranii reveal that the Southern Ocean top predators are nutrient links connecting deep-sea and shelf-slope environments

Deep-sea squids are presumably vital components of largely undescribed marine ecosystems, yet limited access to specimens has hampered efforts to detail their ecological roles as predators and preys. Biochemical techniques such as stable isotope analyses, fatty acid analyses, and bomb calorimetry are increasingly recognized for their ability to infer trophic ecology and dietary information from small quantities of tissue. This study used five opportunistically collected Taningia danae specimens and one Chiroteuthis aff. veranii specimen retrieved from the Great Australian Bight, South Australia, to detail the trophic ecology of these poorly understood squids. Four body tissue types (i.e., arm, buccal mass, mantle, and digestive gland) were assessed for their utility in stable isotope (SI) and fatty acid (FA) analyses, and we found that the arm, buccal mass, and mantle tissues had similar SI and FA profiles, suggesting that they can be used interchangeably when the entire specimen is unavailable. δ13C, δ15N, and fatty acid data suggests that the T. danae and C. aff. veranii specimens lived in the Southern Ocean and were high-trophic-level predators, feeding on deep-sea fishes and small squids, while also taking advantage of the summer upwelling region of the Great Australian Bight. The fatty acid analysis and bomb calorimetry results indicate that these squids might be important reservoirs of essential FAs (EPA and DHA) for Southern Ocean predators and that the whole-body energy content of T. danae individuals can reach up to 362,250 kJ. Our findings indicate that these squids may be contributing greatly to the transport of nutrients and energy between the Southern Ocean deep-sea and the Great Australian Bight shelf–slope environments. In addition to building our understanding of the trophic ecology of two poorly understood deep-sea squids, these findings also highlight the utility of partial specimens and demonstrate the important ecological information that can be obtained from few samples that may be opportunistically collected.

Differences in Physiological Performance and Gut Microbiota between Deep-Sea and Coastal Aquaculture of Thachinotus Ovatus: A Metagenomic Approach.

Aquaculture has become the fastest growing sector in global agriculture. The environmental degradation, diseases, and high density of mariculture has made for an inevitable shift in mariculture production from coastal to deep-sea areas. The influence that traditional coastal and emerging deep-sea farming environments exert on aquatic growth, immunity and gut microbial flora is unclear. To address this question, we compared the growth performance, physiological indicators and intestinal microbiological differences of deep-sea and coastal aquaculture in the Guangxi Beibu Gulf of China. The results showed that the growth performance and the complement of C3 and C4 (C3, C4), superoxide dismutase (SOD), and lysozyme (LYS), these physiological and biochemical indicators in the liver, kidney, and muscle of Trachinotus ovatus (T. ovatus), showed significant differences under different rearing conditions. Metagenome sequencing analysis showed Ascomycota, Pseudomonadota, and Bacillota were the three dominant phyla, accounting for 52.98/53.32 (coastal/deep sea), 24.30/22.13, and 10.39/11.82%, respectively. Aligned against the CARD database, a total of 23/2 (coastal/deep-sea) antibiotic resistance genes were screened and grouped into 4/2 genotypes. It indicated that compared with deep-sea fish, higher biological oxygen levels (3.10 times), inorganic nitrogen (110.00 times) and labile phosphate levels (29.00 times) in coastal waters might contributed to the existence of eutrophication with antibiotic resistance. The results of the study can provide complementary data on the study of the difference between deep-sea farming and traditional coastal farming, serving as a reference to future in-depth work on the transformation of fisheries development and scientific standardization of deep-sea farming.

Enhancing the Sealing Performance of Bolted Ball Joints by Gaskets: Numerical Simulation and Experiment

With the increasing utilization of bolted ball joint steel mesh structures in offshore floating platforms and deep-sea fish cages, the issue of seawater infiltrating the joints and members through the installation gaps of the bolted ball joint, leading to subsequent corrosion, has become increasingly prominent. This article presents an innovative method to improve the sealing performance of bolted ball joints. The approach involves creating sealed surfaces within the contact gaps between the sleeve and connecting components by adding circular grooves and sealing washers to both ends of the sleeve. Subsequently, a two-dimensional finite element analysis model of the bolted ball joint with the sealing structure was created using SOLIDWORKS 2021 and ANSYS Workbench 2022 R1. The study analyzes the sealing gasket’s contact pressure at various compression levels and evaluates its performance with bubble tests for air tightness. Research results show a linear relationship between the contact pressure and compression rate, achieving sealing pressures of 2.91 MPa, 4.22 MPa, and 5.95 MPa at compression levels of 8%, 11%, and 14%, respectively. Experimental testing demonstrates that the improved bolted ball joint exhibits excellent sealing performance.

Distribution and structure of deep-sea demersal fish assemblages across the central and western Pacific Ocean using data from undersea imagery

Demersal deep-sea fish assemblages from islands and seamounts are poorly described, even in the Hawaiian archipelago. Knowledge across all depths, in similar settings, is even sparser for other archipelagos in the central and western Pacific. However, recent remotely operated vehicle (ROV) explorations and archived video from human-occupied submersible dives conducted by the Hawai`i Undersea Research Laboratory (HURL) provide an opportunity to explore the structure of these assemblages. Here we describe demersal fish assemblages across the central and western Pacific, including in four Marine National Monuments, and examine the relationship of the assemblages to depth and environmental conditions. We used data collected from 227 underwater vehicle dives resulting in the identification of 24,837 individuals belonging to 89 families and 175 genera. The most frequently occurring genera at depths of 250-500 m were Epigonus, Setarches, Polymixia, and Antigonia, between 500-1000 m were Chlorophthalmus, Aldrovandia, and Neocyttus, and between 1000-3000 m were Synaphobranchus, Kumba, Halosaurus, Ilyophis, and Ipnops. There are strong changes in the fish assemblages with depth and region, and assemblages become more similar between regions with greater depth. Depth and region explained the most variance in assemblage structure followed by seafloor particulate organic carbon flux (a food supply proxy), concentrations of dissolved oxygen, and salinity. The Line Islands and Tokelau Ridge had the highest values of seafloor particulate organic carbon flux for all depth zones investigated (250-3000 m) and the highest abundance of fishes at 250-500 m and 500-1000 m, respectively. Taxon accumulation curves indicated that diversity at the genus level within all regions and depth bins (except 1000-2000 m and 2000-3000 m) had not been reached with the existing sampling effort. However, when combining samples from all regions, diversity generally appeared to decrease with depth. Overall, this study demonstrates that there are significant regional differences in the composition of the deep-sea fish fauna as well as differences across depth. Such distribution patterns suggest that the four Marine National Monuments (Papahānaumokuākea, Marianas Trench, Pacific Remote Islands, and Rose Atoll Marine National Monuments, encompassing an area of 3,063,223 km2) are not replicates of diversity, but complementary components of the regional fauna.

Feeding ecology and reproductive success of the Little Bittern Ixobrychus minutus in differently managed pond habitats

Knowledge of the relationships between food habits and habitat is crucial for the assessment of habitat quality for birds. The present study investigated the diet and reproductive success of Little Bitterns Ixobrychus minutus nesting on cyprinid fish ponds, an important breeding habitat of this species in central and eastern Europe. Being subject to different management practices, fish ponds provide food resources of uneven availability for this small heron. Prey items regurgitated by nestlings were examined, and breeding success was estimated on monoculture ponds stocked either with small fish (of a size suitable for feeding nestlings) or large fish (unavailable to Little Bitterns and adversely affecting their non-fish prey), on abandoned ponds dominated by small fish but with large fish also present, and on angling ponds dominated by large sport fish but harbouring significant numbers of small fish as well. A total of 1356 prey items from 78 broods were identified. Although Little Bitterns exhibited dietary flexibility in response to the contrasting availability of prey on their nesting ponds, the bulk of the nestlings’ diet consisted of fish. The size of fish brought to the nest increased significantly with brood age, showing that parents adjusted the prey size to the gape constraints of their young. The chick production determined for 73 broods did not differ with respect to pond management, but the dietary composition indicated that to compensate for food shortages, birds nesting on ponds containing mainly large fish made foraging flights to food-richer ponds. The abundance of small-sized fish prey may be a factor limiting the breeding success of small- and medium-sized predatory waterbirds and should be taken into consideration in management strategies of habitats dominated by fish.

Process-based modeling for ecosystem service provisioning: Non-linear responses to restoration efforts in a quarry lake under climate change

Healthy freshwater ecosystems can provide vital ecosystem services (ESs), and this capacity may be hampered due to water quality deterioration and climate change. In the currently available ES modeling tools, ecosystem processes are either absent or oversimplified, hindering the evaluation of impacts of restoration measures on ES provisioning. In this study, we propose an ES modeling tool that integrates lake physics, ecology and service provisioning into a holistic modeling framework. We applied this model to a Dutch quarry lake, to evaluate how nine ESs respond to technological-based (phosphorus (P) reduction) and nature-based measures (wetland restoration). As climate change might be affecting the future effectiveness of restoration efforts, we also studied the climate change impacts on the outcome of restoration measures and provisioning of ESs, using climate scenarios for the Netherlands in 2050. Our results indicate that both phosphorus reduction and wetland restoration mitigated eutrophication symptoms, resulting in increased oxygen concentrations and water transparency, and decreased phytoplankton biomass. Delivery of most ESs was improved, including swimming, P retention, and macrophyte habitat, whereas the ES provisioning that required a more productive system was impaired (sport fishing and bird watching). However, our modeling results suggested hampered effectiveness of restoration measures upon exposure to future climate conditions, which may require intensification of restoration efforts in the future to meet restoration targets. Importantly, ESs provisioning showed non-linear responses to increasing intensity of restoration measures, indicating that effectiveness of restoration measures does not necessarily increase proportionally. In conclusion, the ecosystem service modeling framework proposed in this study, provides a holistic evaluation of lake restoration measures on ecosystem services provisioning, and can contribute to development of climate-robust management strategies.

Organic UV absorbents in the deepwater redfish (Sebastes mentella) from the St. Lawrence Estuary and Gulf: Distribution and human health risk assessment

UV absorbents (UVAs), such as organic UV filters (UVFs) and benzotriazole UV stabilizers (BZT-UVs), are used in a wide range of consumer and industrial products and they are contaminants of emerging concern in the environment. However, their occurrence and fate in the deep-sea environments are inadequately understood. This study investigated the occurrence and distribution of five UVFs and ten BZT-UVs in the muscle (n = 127) of 2019-collected deepwater redfish (Sebastes mentella) from the St. Lawrence Estuary and Gulf (SLEG) (Canada) to better understand the accumulation of these contaminants in deep-sea fish. Small redfish (<30 cm) tended to have higher concentrations of UVAs in the muscle than that of larger specimens (>30 cm). The UVF 2-hydroxy-4-methoxybenzophenone (BP3) was the most frequently detected (present in 34 % of all samples) target UVA, with concentrations as high as 413 ng/g (dry weight). According to the δ15N and δ13C data, pelagic-eating redfish, and individuals with lower trophic levels had higher lipid content and accumulated more BP3 in their muscles. Four BZT-UVs were detected in redfish muscle, but the detection frequency was lower than 30 %. The estimated hazard quotient for these contaminants was <2.3 × 10−2 for general Canadian populations, indicating that they are unlikely to pose health risks to humans through redfish consumption. Factors influencing UVAs bioaccumulation in redfish, as well as the effects UVAs may have on deep-sea species, should be researched further.

Early Pliocene otolith assemblages from the outer-shelf environment reveal the establishment of mesopelagic fish fauna over 3 million years ago in southwestern Taiwan

Understanding the diversity of deep-sea fish fauna based on otoliths in the tropical and subtropical West Pacific has been limited, creating a significant knowledge gap regarding regional and temporal variations in deep-sea fish fauna. To address this gap, we collected a total of 122 bulk sediment samples from the Lower Pliocene Gutingkeng Formation in southwestern Taiwan to reconstruct the otolith-based fish fauna. Using planktonic foraminiferal biostratigraphy, we determined the age of the samples to be 5.6 to 3.1 Ma. A total of 8314 otoliths were assigned to 64 different taxa from 33 families, including the discovery of one new genus, Gutingichthys gen. nov., and three new species: Benthosema duanformis sp. nov., Benthosema parafibulatum sp. nov., and Gutingichthys changi sp. nov. Comparisons with other regional otolith-based assemblages highlighted the exceptional diversity of our collection, making it the most diverse fossil fish fauna reported from Taiwan to date. Otolith diversity analysis revealed very few taxa were dominant in the assemblage, particularly the mesopelagic Myctophidae, with a wide variety of minor taxa. The co-occurrence of shallow-water elements suggests episodic storm events as a potential source. The predominance of deep-sea and oceanic fishes indicated an outer-shelf to upper slope environment, resembling the modern outer-shelf and upper slope fish fauna in the region. Our findings suggest an early establishment and persistent presence of the mesopelagic fish community since the Early Pliocene. Further investigations of the Upper Miocene and Pleistocene sections of the Gutingkeng Formation would provide valuable insights into the evolution of deep-sea fish fauna in the area.

Harnessing a mesopelagic predator as a biological sampler reveals taxonomic and vertical resource partitioning among three poorly known deep-sea fishes

Pelagic predators are effective biological samplers of midtrophic taxa and are especially useful in deep-sea habitats where relatively mobile taxa frequently avoid observation with conventional methods. We examined specimens sampled from the stomachs of longnose lancetfish, Alepisaurus ferox, to describe the diets and foraging behaviors of three common, but poorly known deep-sea fishes: the hammerjaw (Omosudis lowii, n = 79, 0.3–92 g), juvenile common fangtooth (Anoplogaster cornuta, n = 91, 0.6–22 g), and juvenile Al. ferox (n = 138, 0.3–744 g). Diet overlap among the three species was high, with five shared prey families accounting for 63 ± 11% of the total prey mass per species. However, distinct differences in foraging strategies and prey sizes were evident. Resource partitioning was greatest between An. cornuta that specialized on small (mean = 0.13 ± 0.11 g), shallow-living hyperiid amphipods and O. lowii that specialized on large (mean = 0.97 ± 0.45 g), deep-dwelling hatchetfishes. Juvenile Al. ferox foraged on a high diversity of prey from both shallow and deep habitats. We describe the foraging ecologies of three midtrophic fish competitors and demonstrate the potential for biological samplers to improve our understanding of deep-sea food webs.

Spatial distribution and speciation of mercury in a recovering deepwater redfish (Sebastes mentella) population from St. Lawrence Estuary and Gulf, Canada

Mercury (Hg) pollution poses a significant threat to the environment, particularly in the form of methylmercury (MeHg). However, little is known about the distribution and influencing factors of Hg in deep-sea (>200m) fish, which is crucial for assessing potential health risks to fish and humans. In Canada, the deepwater redfish (Sebastes mentella) has been designated as an endangered species. After a 25-year fishing moratorium, the redfish population in the St. Lawrence Estuary and Gulf is recovering, and resuming of commercial fishing and human consumption are expected. This study aimed to investigate the distribution of MeHg and total Hg (THg) in the muscle of redfish, as well as the factors influencing its distribution, and to assess the potential human health risks associated with redfish consumption. The redfish samples (n = 123) were collected by Fisheries and Oceans Canada in 2019. The concentrations of THg and MeHg in redfish muscle were determined to be 93.3 ± 183 ng/g (mean ± SD, wet weight) and 78.2 ± 149 ng/g, respectively. Large redfish (>30 cm) accumulated 20 to 30 times more Hg than small redfish (17–30 cm). Small redfish from the Estuary-Western Gulf had higher levels of MeHg and THg than those from the Laurentian Channel and the Northeast Gulf, but the Hg availability to redfish among the three areas were similar. Significant predictors of MeHg concentrations in redfish muscle were determined to be fish length, muscle moisture, δ15N, and N%. MeHg consumption by the general population with an average fish consumption rate is not anticipated to have adverse effects. This study establishes a baseline for future Hg monitoring in the deep water environments in this region. Further research is required to elucidate the cause-effect relationships between various environmental/biological parameters and Hg accumulation in deep-sea biota.

Women’s Active Engagement with the Sea Through Fishing in Fiji

ABSTRACT Fiji’s iTaukei (Indigenous) women contribute significantly to small-scale coastal fisheries, and are therefore integral to successful fisheries (co-)management, yet their role still remains underestimated. This paper explores an original pathway to highlight iTaukei women’s role in Fiji’s small-scale coastal fisheries; a pathway that, through a ‘dwelling perspective’, emphasises the socialities that are inseparable from this role. It is based on data collected during two distinct fieldwork periods, 2003–2004 and 2016–2018, in a village located on Gau, Fiji’s fifth biggest island, in Lomaiviti Province. An overview of the fishing practices of the iTaukei women living in this village shows that fishing can be seen as both a gender-differentiated and a more-than-human, dynamic field of sociality. Furthermore, we argue that fishing is these women’s main mode of active engagement with their marine environment, conceived as inseparable from land, and all its sentient constituents. This mode of engagement reflects the relational ontology inherent in the iTaukei all-encompassing concept of vanua, which includes a sense of environmental responsibility and stewardship. This mode of engagement and its ‘procurement’ dimension are adjusted over time through ‘friction’ with conservation regulations and ideas that are both internal and external to the fishing community. These conservation regulations and ideas are related to community-based marine resource initiatives, as well as to national fisheries management concerns and measures (including species-specific fishing bans). They give a supplemental dimension to women’s interactions and engagement with the sea and its sentient constituents, far from reducing those to a mere divide between ‘nature’ and society/sociality.