Beach Seine Research Articles

Lakeshore areas of conservation interest: Characteristics of nursery areas of the threatened lake‐dwelling grayling, Thymallus thymallus

AbstractResearch‐based knowledge is essential for effective conservation and restoration of threatened aquatic species and habitats. Here, our aim was to gather this knowledge on the lake‐dwelling grayling (Thymallus thymallus), typically a riverine fish. Such atypical populations are particularly vulnerable to anthropogenic impacts, including fishing pressure, climate change, eutrophication and waterway construction, some of which affect especially the early life stages. However, there is little information available to guide management and conservation of grayling in lakes. Accordingly, we assessed characteristics of the nursery areas in the threatened grayling population of Lake Puruvesi (eastern Finland). In particular, we used beach seines in two consecutive years to sample lakeshore sites (including islands) that were a priori presumed suitable for grayling. We assessed the occurrence of grayling fry (larvae and post‐larvae <40 mm in length) regarding depth, year, the site's exposure (fetch), bottom shear stress, substrate coarseness and shoreline's north–south orientation. Overall, we found grayling fry in low numbers at every fourth site, with the sites’ exposure and dominant substrate coarseness being most relevant variables. In particular, more exposed sites (i.e. with higher fetch values) and fine‐grained substrates dominated by sand or gravel had more grayling fry. Average depth, bottom shear stress or shoreline orientation along the north–south axis did not have a significant effect. Together, the results suggest that the most important nursery areas for lake‐dwelling grayling are lakeshore zones that are barren and exposed. Hence, the sites share characteristics with those used for reproduction by the more common riverine grayling. We hope that these findings will facilitate lake‐dwelling grayling's management and conservation efforts.

Length-weight relationships of four difficult-to-sample Caspian endemic gobies (Teleostei: Gobiidae): Benthophilus persicus, Benthophilus baeri, Knipowitschia longecaudata, and Hyrcanogobius bergi

The present study provides the length-weight relationships (LWRs) for four difficult-to-sample Caspian endemic gobies for the first time: Benthophilus persicus, Benthophilus baeri, Knipowitschia longecaudata, and Hyrcanogobius bergi. They were collected from shallow and deep waters of the southwestern Caspian Sea using various methods, including beach seining, scuba diving, and deepwater bottom beam trawls. The slope (b) of LWRs ranged from 2.874 for B. baeri, to 3.408 for H. bergi with coefficient of determination higher than 0.918. The b values showed significant differences between the sexes of all species.

Early-Life Population Parameters and Hatch-Date Analysis of Sharpsnout Seabream (Diplodus puntazzo Walbaum, 1792) Juveniles in the Sea of Marmara, Türkiye

This research aims to determine early-life population parameters and hatch date of sharpsnout seabream (Diplodus puntazzo Walbaum, 1792) juveniles using microstructure analyses of sagittal otoliths collected from the Sea of Marmara, Türkiye. Specimens were collected using an experimental beach seine at 12 stations from November 2021 to March 2022. The mean catch per unit effort (CPUE) was 1.1 individuals per haul, with 44.4% of the total D. puntazzo specimens collected at the Erdek Station. A negative allometric growth was calculated from the length-weight relationship equation (W=0.0178L2.698). The daily age ranged between 39 days-1 and 141 days-1, with a mean of 78.9 ± 2.29 days-1. The daily growth rate and mortality ratio were calculated as 0.213 mm/day and 4.38%, respectively. The hatching mainly occurred in September and October.

Spatial fish distribution in autumn in a shallow mesotrophic lake, assessed by hydroacoustic surveys, trawling, and beach seining.

Day and nighttime autumn fish abundance and biomass were studied in the pelagic and littoral zones of Lake Sauka in Latvia. Both pelagic methods (hydroacoustics and trawling) revealed significantly higher fish abundance and biomass during the day than at night, especially in deeper zones (below 3 m). Roach (Rutilus rutilus) and Eurasian perch (Perca fluviatilis) dominated the trawl catches during the day, while roach and ruffe dominated at night. Fish smaller than 14 cm strongly dominated in both the trawl catches and hydroacoustic observations. Our hydroacoustic sampling found inhomogeneous pelagic distributions of fish aggregated in big shoals during the day. In the littoral zone, which was sampled by beach seining, both the abundance and biomass were significantly higher at night than during the day. Roach, bleak, and European perch usually dominated in beach seine catches during the day and at night. The daytime pelagic biomass found by hydroacoustics was 62 kg/ha and it decreased to approximately 11 kg/ha at night. The littoral biomass found by beach seining was diurnally opposite, 4 kg/ha during the day and 37 kg/ha at night. It is obvious that diurnal horizontal migrations between pelagic and littoral zones, and shoaling behavior during the daytime are common patterns in the shallow Lake Sauka during the autumn. The study of the spatial distribution of fish is extremely important for the establishment of an appropriate monitoring plan for the purposes of the Water Framework Directive with regard to the morphometry of the lake, the geographical location, and the sampling period of the year. This study also shows that the combination of completely non-invasive hydroacoustic and other methods that are invasive (trawls, beach seines) but not as destructive as gillnets, which are normally used for scientific fish monitoring in Europe, could be a future way forward for fish monitoring.

Imperfect detection and misidentification affect inferences from data informing water operation decisions

AbstractObjectiveManagers can modify river flow regimes using fish monitoring data to minimize impacts from water management infrastructure. For example, operation of the gate‐controlled Delta Cross Channel (DCC) in California can negatively affect the endangered Sacramento River winter‐run Chinook Salmon Oncorhynchus tshawytscha. Although guidelines have been developed for DCC operations by using real‐time juvenile fish sampling count data, there is uncertainty about how environmental conditions influence fish occupancy and the extent to which those relationships are affected by sampling and identification error.MethodsWe evaluated the effect of environmental conditions, imperfect detection, and misidentification error on salmon occupancy by analyzing data using hierarchical multistate occupancy models. A total of 14,147 trawl tows and beach seine hauls were conducted on 1058 sampling days between October and December from 1996 to 2019. During these surveys, 2803 juvenile winter‐run Chinook Salmon were identified, and approximately 29% of the sampling days had at least one winter‐run juvenile detected.ResultThe probability of misidentifying an individual juvenile winter‐run Chinook Salmon in the field was estimated to be 0.056 based on fish identification examinations and genetic sampling. Occupancy varied considerably and was related to flow characteristics, water clarity, weather, time of year, and whether occupancy was detected during the previous sampling day. However, these relationships and their significance changed considerably when accounting for imperfect detection and the probability of misidentifying individual juvenile salmon. Detection was <0.3 under average sampling conditions during a single sample and was influenced by flow, water clarity, site, and volume sampled.ConclusionOur modeling results indicate that DCC gate closure decisions could occur on fewer days when imperfect detection and misidentification error are not accounted for. These findings demonstrate the need to account for identification and detection error while using monitoring data to assess factors influencing fish occupancy and inform future management decisions.

Food Selectivity in Juvenile Three-Spined Stickleback Gasterosteus aculeatus L. (Gasterosteidae) at Nursery Grounds in the White Sea

The spatial and temporal variability in the dietary preferences of juvenile three-spined stickleback Gasterosteus aculeatus were studied across the typical coastal habitats of Keret Archipelago, Kandalaksha Bay(the White Sea). The sampling of fish using a beach seine was conducted in the late July–early August period and in late August. Additionally, zooplankton samples were collected to conduct a quantitative assessment of the abundance of potential prey items. The similarity percentage (SIMPER) analysis was applied to the data obtained from the stomach content and revealed the five planktonic taxa most prominently contributing to the diet of juvenile sticklebacks. Among these, the copepod Temora longicornis was the most important prey item at marine sites, while Acartia longiremis dominated the diet of fish in the marine lagoon. The calculation of the selectivity index revealed that some taxa (such as A. longiremis) were always avoided by juvenile fish, whereas the selectivity of some taxa increased in late August. In general, juvenile sticklebacks demonstrated a pronounced individual variation in their selectivity, even when a particular prey item was selected positively during the whole period of study. Our data highlight that despite the predominant consumption of easily available prey by juvenile sticklebacks, they demonstrate taxonomic- and size-specific prey selectivity.

Before and after closed season for beach seine fishing in Ghana: Impact on benthic macroinvertebrates species diversity indices

AbstractBeach seine fishery provides a means of livelihood to many households in Africa and it is widely practiced in the coastal communities of Ghana due to the relatively cheaper operational cost. However, the small mesh sizes of beach seine nets and fishing activities that involve dragging a net through the nearshore seabed tend to destroy fish breeding grounds and capture juvenile fish and non‐target benthic macroinvertebrates, which get discarded. This study investigated the impact that before and after closed season for beach seine fishing had on macroinvertebrates species diversity indices at two Ghanaian beaches with different fishing pressures. The study was carried out at OLA and Sisimbo Beaches located in the Central Region of Ghana, taking advantage of the statutory 1‐month national fishing closed season in July 2022. Six (6) replicate sediment samples were taken at each beach after landing by beach seine fishers every month for 6 months, from April to June, and August to October, representing before and after closed season, respectively. Benthic macroinvertebrates were retrieved from the samples using appropriate protocols and subjected to indirect (Shannon, Simpson, Rényi) and direct (species abundance models, species accumulation models, multivariate statistics) measures of species diversity analyses. The indirect species diversity indices increased monotonically the following 2 months after closed season but reduced in the third month after closed season at both beaches. Conversely, the direct measures of diversity indices revealed that closed season for beach seine fishing improved species numbers and richness at both study beaches. This is the first report on the impact of a closed season on macroinvertebrates in any African country.

Population Dynamics of Shortfin Scad (Decapterus macrosoma) Bleeker 1851 in Babuyan Channel, Philippines

The study was conducted to determine the status of Decapterus macrosoma stocks in the Babuyan Channel. Data were collected from January 2016 to December 2017 following the standard methodology of the National Stock Assessment Program (NSAP). The data were analyzed using the Fisheries Stock Assessment Tool II software and R package. Results showed that the species is available throughout the year and is most productive during summer. Decreased catch landings were affected by environmental, biological, social, economic, and regulatory factors. Beach seine has the largest contribution of catch but has the most number of immature catches. The highest catch per unit effort for all the gears occurs from February to June. Fishing mortality for beach seine (F = 2.98) is higher than the natural mortality (M = 1.76) values, indicating that the species is already experiencing high fishing pressure. D. macrosoma exhibited a bimodal mode or recruitment with unequal strengths. Similarly, the observed exploitation ratio (E = 0.63) is beyond the sustainable exploitation level. In order to sustainably manage the species population, introducing environment-friendly gear, banning beach seine, and establishing Marine Protected Areas should be implemented to support species productivity. These are some of the effective management measures being implemented in different parts of the country and found in the study of Cabigas et al. (2012), Valdemarsen and Suuronen (2001), and Hilborn and Ovando (2014).

The management of common carp fisheries using spawning potential ratio in the southeast of the Caspian Sea

AbstractSpawning potential ratio (SPR) is an important index used by fisheries biologists and managers to determine how a fishery should be harvested to prevent recruitment overfishing. In the southeastern Caspian Sea, Iran, 3430 common carp Cyprinus carpio were caught by beach seine in 2‐week intervals of two fishing seasons in 2019 and 2020. Fork length (FL) was measured to the nearest 1 cm. The age and maturity stage of 434 specimens, including 236 females and 198 males, were estimated by scale and gonad microscopic examinations. Estimated L∞ was 71.9 and K (growth constant) was 0.09. Instantaneous total mortality (Z) was 1.08, natural mortality (M) was 0.18, and fishing mortality (F) was 0.9. Estimated SPR at current fishing mortality (0.18) was lower than the reference point (0.4). Our findings indicated that fishing mortality should be reduced to F = 0.38 for C. carpio to meet the SPR reference point of 0.4. Further, higher minimum length limits should be set to reduce fishing mortality, and catch quotas for fishing cooperative corporations should be considered to meet the 40% SPR threshold.

Histological structure of the digestive tract, liver, and pancreas of Ambassis nalua (Hamilton, 1822) with ultrastructural details of the gastric gland.

The scalloped perchlet Ambassis nalua is one of the dominant fishes in the Estuarine Pranburi River, Thailand. It is suggested that this fish is in the secondary trophic level with a carnivorous nature. Studies on digestive system will help us further identify the niche of this species in the food web/food chain. The present study therefore aimed to report the detailed structure and ultrastructure of A. nalua digestive system. Fish samples (n = 30) with a total length of 5.7 ± 0.5 cm were obtained using beach seines from the Estuarine Pranburi River. Their digestive tract length and intestine coeficient were 3.6 ± 0.07 cm and 0.91, respectively. Light microscopic observation showed that the digestive wall comprised four layers, namely mucosa, submucosa, muscularis, and serosa. The prominent mucous-secreting cells were found in the mucosal oesophagus. The stomach had many gastric folds, with height and width being 649.76 ± 85.15 and 370.30 ± 68.56 μm, respectively. Gastric glands were found in the anterior stomach but not in the posterior stomach. Each gastric gland was made up of a single type of columnar cells. The gastric cells were ultrastructurally characterized by numerous mitochondria and well-developed secretory granules of varying sizes. A few small vacuoles were also identified in the apical area of the gastric cells. The intestine had two regions (anterior and posterior intestines), and pyloric caecum was absent. The density of the goblet cell was significantly higher in the posterior intestine. These results provide basic knowledge of the digestive system of A. nalua, and the low intestine coefficient and the absence of pyloric caecum suggest the carnivorous feeding habit of this species.

Beach Seine Fisheries in the United Arab Emirates on Sea of Oman

The catch of beach-seine operating in East Coast of the United Arab Emirates during the period from January to December 2022 was investigated. The catch composition was represented by 37 species belong to 22 families. Engraulidae, Leiognathidae, Clupeidae and Carangidae were the most dominants families, represented by 34.21, 22.62, 19.28 and 11.14% in mass respectively. A total of 46210kg of fish were caught by 41 beach seines in the study areas. Monthly CPUE ranged from 430 to 1446kg per operation. The highest CPUE was recorded in March, while the lowest CPUE was in July. In the present study, the average catch of beach seine was 1,127.07kg/haul/boat. In conclusion, the use of beach seines for fishing can help to sustainably manage fisheries by targeting specific populations of fish and reducing bycatch. It can also provide food and income for local communities.

Spatiotemporal Variability in Fish Assemblages in a Coastal and Estuarine System in the Tropical Eastern Pacific during the Anthropause

Differences in fish assemblages’ composition and their relationship with the environmental variables were analyzed in the Urías estuarine system, Mexican North Pacific. Environmental variables and fish catches were recorded bimonthly between June 2018 and November 2021, including a period before and during the COVID-19 pandemic. Multivariate analyses were performed in the studied area to define zones based on their environmental, biotic, and abiotic characteristics and the effect of these on the fish assemblages. Two zones were identified, an estuarine with mangrove forest and a surf zone in the coastal area outside the estuarine system. Fish composition, biomass, and diversity (α and β) were evaluated among the factors of the period (before–during COVID-19), climatic seasons, and zones. A total of 5947 fish individuals of 41 species were collected using beach seines as fishing gear. The structure of the fish assemblages was different between zones and periods. Abiotic (temperature, salinity, and total matter suspended), biotic (mangrove area), and temporal (season and period before–during COVID-19) variables had an effect on fish biomass and α diversity, while the results of the β diversity only indicate changes in the nestedness component before–during the lockdown. These results indicate a change in fish assemblages’ structure and composition between periods, which might be a consequence of the limitation of human activities derived from the pandemic, climatic changes, or a combination of both effects. Our results show that fish assemblages in the estuarine systems of the Tropical Eastern Pacific are unique, and there is a need to establish local management strategies for these ecosystems.

The effect of time and sea surface temperature on the total catches of beach seines in Gampong Jawa, Banda Aceh, Indonesia

Research of the influences of time and sea surface temperature toward catch of beach seines at Gampong Jawa, Banda Aceh conducted in December 2021 for 15 days. This research aims to analyze the composition of the number of beach catches, discover the effect of time on the number of catches of beach seines, to describe the sea surface temperature in the Gampong Jawa waters. The method used in this research uses a survey method through observing and collecting information directly at the research location; the data were analyzed descriptively and presented in the form of tables or charts. The results showed that the composition of dominant catches of beach seines in Gampong Jawa in the morning was dominated by petek fish (Leiognathus equulus) as much as 23% and in the afternoon dominated by moonfish (Megalops cyprinoides) with a percentage of 62%. The difference in catch time between morning and afternoon tends to have an impact on the catch where the best fishing time is in the afternoon. Based on statistics with paired t test obtained a significant value of 0.023 <α value of 0.05, morning and afternoon time has an effect on the number of fish caught. Then the sea surface temperature during the study was in the range of 27 ºC to 29 ºC.

A Preliminary Studies of Fish Richness in the Tondano River Estuary Manado Bay

The purpose of this study was to analyze the richness of fish species in the Tondano River estuary. Sampling was done for two months, in July and August 2022, new moon phase, during the low tide at 13.00-16.00 pm.  Sampling used a 20-m beach seine with a cod-end part of 0.2-cm mesh and wings of 2-m height and 1.5-cm mesh.  The beach seine was operated 10 times starting from the lowest tide at 13.00 pm to the tide condition at 16.00 pm. As a whole, 736  individuals were caught, consisting of 24 species and 17 families, 14 migrant species, and 10 resident species   The number of fish varied from 1 to 445 individuals,  in which Terapon jarbua (445 ind) was the most abundant, followed by Neovespicula depressifrons (70 ind). The dominant index  (C) was 0.38 and the diversity index (H) was 1.65.  The resident species were 120 individuals varying from 2 to 70 ind., and the most abundant was   Neovespicula depressifrons (70 ind.). The dominant index (C) was 0.37 and the diversity index was 1.47. 

Plastic waste and fish landed by beach seine fishers in coastal Ghana.

Baseline data on plastic landing by fishers and monitoring of this is important in evaluating the success of plastic waste management efforts. This study investigated plastic and fish landed by beach seine fishers in Ghana together with the rate of plastic deposition on an adjoining beach. Plastic constituted 31.6% of the total catch and 41.7% of the fish landed by weight. There were significant differences between the average weight of fish (139.58 ± 53.6 kg) and plastic (65.73 ± 14.6 kg) landed per fishing session and the catch per unit effort of fish (183.4 ± 76.7 kg/day) and plastic (88.4 ± 35.2 kg/day). The mean weight of plastic landed per fishing session was higher than the mean weight of each of the 26 species of fisheries. The rate of plastic deposition on the beach was 8.1 ± 2.5 plastic items per m2 per tidal cycle or 0.35 ± 0.11 kg plastic per m2 per tidal cycle with food packs and tableware dominating the deposited plastic. The results suggested ongoing water sachets and plastic bottle recycling in Ghana are yielding results and calls for targeted efforts in plastic food packs and tableware management.

Stock assessment of Larimus breviceps, a bycatch species exploited by artisanal beach seining in Northeast Brazil

AbstractMotorized trawling was banned off part of the Brazilian coast in 1990 due to environmental impacts, thus artisanal fishermen adopted large beach seines as an alternative. No impact assessments have been conducted on any species; therefore, we examined the life history and stock status of shorthead drum, Larimus breviceps, a primary bycatch in tropical shrimp fisheries. Between 2016 and 2017, 969 shorthead drum were collected and analyzed using ELEFAN‐based models. Females were larger, more abundant, and older than males. Capture rates of juvenile were high, and no mega‐spawners were found. Integrated stock assessment indicated slight overexploitation and growth overfishing. Increased yield per recruit was indicated by high length at first capture. Shorthead drum segregate ontogenetically by size. Growth, mortality, and longevity may be temperature‐influenced. We found that beach seine fisheries may impact shorthead drum by population depletion and potential disruptions to reproductive capacity and recommend further studies and management to improve sustainability.

Impact of Marine Debris to Fishing Operation at Ambon Bay

Marine debris is a serious problem around the world. The entry of garbage into the sea not only threatens the survival of various marine organisms but also disturbs fishing activities, thereby reducing fishermen’s production and income. This study aimed to identify the fishing gear damaged by marine debris during fishing operations and analyze how much the marine debris impacted the production of various fishing units. Data were obtained from 101 fishermen operating at Ambon Bay by observation, interview, and descriptive analysis. Obstacles by the trash during fishing operations are among the trash twisted or attached to fishing gear; trash are twisted at the propeller of the boat and damage the fishing gear. On the fishing line group, the main hurdle is on the vertical hand line, where the trash are entangled at the hook; on the gill net group, the main hurdle is on the bottom gill net, where the trash are twisted to body net; and on the seine group, the main constraint is on the beach seine, where the trash are trapped in the cod end. This condition causes a decline in production, with the biggest impact on the bottom gill net, with a decrease in production of 4.38% from the average production per trip.

Population parameters of the non-indigenous invasive shrimp Palaemon macrodactylus Rathbun, 1902 (Caridea: Palaemonidae) from the southeastern Caspian Sea, with implications for range expansions, threats and conservation

Knowledge on invasive species is critical for the conservation. This study is the first documentation on population parameters of oriental shrimp (Palaemon macrodactylus) in the southern Caspian Sea, where the occurrence of invasive species is of great importance. The samples were collected using a small beach seine (35 m long and 2.5 m height) monthly from April 2019 to March 2020, and a total of 1643 specimens of P. macrodactylus were sampled. The growth form of the males was negative and that of females positive allometric nature. From the size-frequency distributions, the shrimp's lifespan was estimated to be about 2 years for both sexes. High recruitment can take place over nearly all months of late summer and autumn. The VBGF parameters were L∞ = 65.00 mm, K = 0.82 y−1, and t0 = −0.80 for males, and TL∞ = 71.00 mm, K = 0.51 y−1 and t0 = −0.59 for females. The estimated Z was 3.65 and 3.10 year−1 for males and females, respectively. The total sex ratio was significantly biased toward females in the population. Length group analysis showed a clear pattern of female dominance in lengths larger than 29 mm. Based on the occurrence of ovigerous females, the reproductive period lasts for seven months (April–October). Fecundity, as the number of both eyed and non-eyed eggs per clutch of females, varied from 71 to 2308 eggs shrimp−1 with a mean of 1074 ± 553.8 (±SD) eggs shrimp−1. The estimated relative number of eggs in a clutch of ovigerous females varies between 1208.8 and 1714, with a mean value of 889.1 eggs. female−1. The egg diameter averaged 0.675 ± 0.063 mm (±SD), ranging from 0.512 to 0.812 mm. The relationships of the total and relative number of eggs in a clutch of ovigerous females with their size were statistically significant, while the egg diameter in ovigerous females was independent of shrimp size (length and weight). P. macrodactylus underwent a life-history strategy including high abundance, short life span, high mortality rate, long reproductive season, and female dominance that showed characteristics of r-strategist species, promoting the invasion of this shrimp in the Caspian Sea as a new area of introduction. We are convinced that P. macrodactylus established in the Caspian Sea it is in the last stage of invasion (impact on the ecosystem).

Характеристика прибережних угруповань риб гирлової ділянки р. Віта та проток Дніпра

Purpose. To investigate the current state of nearshore fish communities and peculiarities of aquatic plants and zoobenthos distribution in the Vita River mouth and Dnipro River channels. Methodology. The study was carried out in summer and autumn 2022 at 4 sampling sites in the Vita River mouth and at 3 sampling sites in Dnipro River straits in the Zhukov Island area. Fishes were caught by a beach seine (6 m in length, 1.5 m in height, 1.5 сm mesh size). Two to three hauls were made at every site depending on the riverbank and bottom structure. Fishes were identified to the species level keeping them in containers with fresh water. Then they were released alive to the river. Findings. Higher aquatic vegetation of the investigated area of the Dnipro River straits was presented mainly by high grasses and attached vegetation with free-floating leaves (associations of common reed Phragmites australis – crisp-leaved pondweed Potamogeton crispus; common reed Phragmites australis + lesser bulrush Typha angustifolia – Potamogeton crispus; yellow water-lily Nuphar lutea). These sites were characterized by optimal oxygen regime for the development of periphyton and lithophilic groups of zoobenthos, the main prey for benthophagous and euryphagous fishes. The biomass of benthic invertebrates was 9.44 g/m2, and their abundance was 24400 ind./m2. In the Dnipro straits, 25 fish species of 5 genera were recorded. Two thirds of them were native species; the most abundant were white bream (Blicca bjoerkna Linnaeus, 1758), roach (Rutilus rutilus Linnaeus, 1758), and monkey goby (Neogobius fluviatilis Pallas, 1814). The share of neolimnetics was 28%, among which gobies (Gobiidae) dominated. In general, long-cycle fishes dominated (44%). Of total species number, 52% were limnophiles, and 32% were reophiles. The share of the psamolithophiles was 40%, and phytophiles were 40%. It shows that these river reaches are very important for spawning the mentioned ecological groups of fish. In the Vita River mouth area, the free-floating vegetation dominated, which was represented by associations of salvinia or floating fern (Salvinia natans) and common or small duckweed (Lemna minor). The dominant phytophilous group of zoobenthos had a biomass of 5.78 g/m2 and abundance of 8365 ind./m2. In the this area, 14 fish species of 7 genera were registered, the most abundant of which were white bream (Blicca bjoerkna Linnaeus, 1758), rudd (Scardinius erythrophthalmus Linnaeus, 1758), and roach (Rutilus rutilus Linnaeus, 1758). The native species formed the maximal share of the fish fauna. Of total species number, 14.3% were neolimnetics and 14.3% remote invaders. Fish community of coastal areas of the Vita River was presented by long and medium cycle species. The share of indifferent and limnophiles fish species were 50 and 43% respectively. Phytophiles dominated in relation to the spawning substrate (57%). Five fish species are included into the protection lists of various levels: knife (Pelecus cultratus Linnaeus, 1758), European bitterling (Rhodeus amarus Bloch, 1782), ide (Idus idus Linnaeus, 1758), common nase (Chondrostoma nasus Linnaeus, 1758), asp (Aspius aspius Linnaeus, 1758). Originality. A comprehensive analysis of vegetation associations, zoobenthos and fish communities of the Vita River mouth area and Dnipro River straits was carried out. Ecological structure of the littoral fish communities was established by species composition and relative abundance, the feeding type, life cycle, spawning type and relation to the water current. In the studied area, the pumpkinseed or common sunfish (Lepomis gibbosus Linnaeus, 1758) was recorded for the first time. This indicates its naturalization and range expansion. Practical value. The preservation of the landscape and biotope conditions of the Vita River mouth area and adjacent Dnipro straits is important for the reproduction of typical ichthyological communities of the Dnipro River middle section. The detection of rare species in these areas provides grounds for expansion of the Emerald Network for fishes included in Resolution 6 of the Bern Convention, as well as for the protection of natural habitats, which are included in Resolution 4 of the Bern Convention. Key words: fish communities, rare species, alien species, Emerald Network.

A comparison of biomonitoring methodologies for surf zone fish communities.

Surf zones are highly dynamic marine ecosystems that are subject to increasing anthropogenic and climatic pressures, posing multiple challenges for biomonitoring. Traditional methods such as seines and hook and line surveys are often labor intensive, taxonomically biased, and can be physically hazardous. Emerging techniques, such as baited remote underwater video (BRUV) and environmental DNA (eDNA) are promising nondestructive tools for assessing marine biodiversity in surf zones of sandy beaches. Here we compare the relative performance of beach seines, BRUV, and eDNA in characterizing community composition of bony (teleost) and cartilaginous (elasmobranch) fishes of surf zones at 18 open coast sandy beaches in southern California. Seine and BRUV surveys captured overlapping, but distinct fish communities with 50% (18/36) of detected species shared. BRUV surveys more frequently detected larger species (e.g. sharks and rays) while seines more frequently detected one of the most abundant species, barred surfperch (Amphistichus argenteus). In contrast, eDNA metabarcoding captured 88.9% (32/36) of all fishes observed in seine and BRUV surveys plus 57 additional species, including 15 that frequent surf zone habitats. On average, eDNA detected over 5 times more species than BRUVs and 8 times more species than seine surveys at a given site. eDNA approaches also showed significantly higher sensitivity than seine and BRUV methods and more consistently detected 31 of the 32 (96.9%) jointly observed species across beaches. The four species detected by BRUV/seines, but not eDNA were only resolved at higher taxonomic ranks (e.g. Embiotocidae surfperches and Sygnathidae pipefishes). In frequent co-detection of species between methods limited comparisons of richness and abundance estimates, highlighting the challenge of comparing biomonitoring approaches. Despite potential for improvement, results overall demonstrate that eDNA can provide a cost-effective tool for long-term surf zone monitoring that complements data from seine and BRUV surveys, allowing more comprehensive surveys of vertebrate diversity in surf zone habitats.