Beam Trawl Research Articles

First record of the fourfinger threadfin, Eleutheronema tetradactylum (Shaw, 1804) in Belgium

A single small specimen (810 mm total length) of polynemid fish was caught in the Zeeschelde, near the village of Branst. The fish was captured in a mid-water beam trawl from an anchored boat in September 2016. It is the first record of Eleutheronema tetradactylum (Shaw, 1804) in Belgium.

Habitat Differences in Deep-Sea Megafaunal Communities off New Zealand: Implications for Vulnerability to Anthropogenic Disturbance and Management

Research on benthic communities in the deep sea has focused largely on habitats in isolation, with few studies considering multiple habitats simultaneously in a comparable manner. The present study aimed to determine the structural differences in benthic communities of continental slope, seamount, canyon, vent, and seep habitats, and assess their relative vulnerabilities to disturbance from bottom trawling and potential seabed mining. Megafaunal invertebrate communities of these habitats were sampled in two regions off New Zealand, in four depth strata between 700 and 1500 m, using an epibenthic sled and a beam trawl. Patterns of community and trophic structure, and the potential influence of environmental variables, were determined using multivariate analyses. The difference in community structure between regions was greater than among habitats and depth strata. Levels of food availability may explain regional differences in community structure, although some influence of fishing disturbance is also possible. Differences in community and trophic structure were most pronounced between the chemosynthetic vent and seep habitats, and other habitats. Differences among these other habitats within a region were inconsistent, except that canyon and slope communities always differed from each other. Community and trophic structural patterns were partly explained by the environmental differences observed among habitats. The relative vulnerabilities of benthic communities to human disturbance in the two regions were determined based on patterns of abundance and feeding mode of the megafauna. Communities of vent and seep habitats were assessed to be more vulnerable to disturbance than those of the other habitats based on a number of habitat-related attributes. However, the relative vulnerability of megafaunal communities at slope, canyon, and seamount habitats could not confidently be assessed on a habitat basis alone. The results of the present study have implications for how regional and habitat differences in benthic communities are incorporated into spatial management options for the deep sea.

Pulse trawling: Evaluating its impact on prey detection by small-spotted catshark (Scyliorhinus canicula)

Pulse fishing may pose a promising alternative for diminishing the ecosystem effects of beam trawling. However, concerns about the impact on both target and non-target species still remain, amongst others the possible damage to the electro-receptor organs, the Ampullae of Lorenzini, of elasmobranchs. The current study aimed to examine the role of pulsed direct current (PDC) used in pulse trawls on the electro-detection ability of the small-spotted catshark, Scyliorhinus canicula. The electroresponse of the sharks to an artificially created prey-simulating electrical field was tested before and after exposure to the pulsed electrical field used to catch flatfish and shrimp. No statistically significant differences were noted between control and exposed animals, both in terms of the number of sharks exhibiting an electroresponse prior to and following exposure as well as regarding the timing between onset of searching behaviour and biting at the prey simulating dipole. These results indicate that, under the laboratory circumstances as adopted in this study, the small-spotted catshark are still able to detect the bioelectrical field of a prey following exposure to PDC used in pulse trawls. However, to fully grasp the impact of PDC on elasmobranchs, further studies are imperative, including examining the effect on reproduction and young life stages, the longer-term and indirect influences and experiments under field conditions.

PROTEKER: implementation of a submarine observatory at the Kerguelen Islands (Southern Ocean)

In the context of global climate change, variations in sea surface temperature, sea level change and latitudinal shifts of oceanographic currents are expected to affect marine biodiversity of the sub-Antarctic islands located near the polar front, such as the Kerguelen Islands, particularly in coastal waters. Sampling sites of previous oceanographic programmes focused on the Kerguelen Islands were revis-ited during three scientific summer cruises aboard the trawler La Curieuse (2011–2014). Among 18 coastal sites explored using scuba diving, 8 were selected for monitoring, as representative of the Kerguelen sub-Antarctic marine habitats, to be progressively equipped with sensors and settlement plots. Remotely operated vehicle (ROV) observations and beam trawling (at 50 m and 100 m) have also been used to contextualise them. Eight sites – in the Morbihan Bay (4), and in the north (2) and south (2) of the Kerguelen Islands – are now monitored by photo and video surveys, with temperature loggers installed at 5 m and 15 m depth, and settlement plots at about 10 m depth. Temperature data have been recovered yearly since 2011 at some sites (those equipped first). Biodiversity found on settlement plots will be characterised yearly by metagenomics. The often harsh conditions at sea involve using robust underwater equipment and simple investigation techniques and protocols to ensure the permanence and the reliability of the equipment installed.

Long-term changes in species composition of demersal fish and epibenthic species in the Jade area (German Wadden Sea/Southern North Sea) since 1972

Within this long-term study, the short- and long-term variability of demersal fish and epibenthic species in relation to temperature and climate-driven environmental changes in the inshore tidal bay system of the Jade area was investigated. Semiquantitative sampling took place once per spring and summer period from 1972 to 2014 by using a 2 m beam trawl at one station in the Jade area (German Wadden Sea/southern North Sea). Min/max autocorrelation analysis (MAFA) and Mann-Kendall analysis revealed significant increasing trends in total abundance and species number. Homogeneity analysis revealed shifts for abundance in spring and summer in the late 1980s and for species number in the late 1980s in spring and early 2000s in summer. Abundances of the estuarine crustacean species Carcinus maenas and Liocarcinus holsatus and of the estuarine fish species Pomatoschistus spp. showed significant increasing abundances since the late 1980s. The marine juvenile species Pleuronectes platessa and Limanda limanda showed significant decreasing abundances, while abundances of Solea solea showed significant increasing abundances since the early 2000s. Abundances of L.holsatus and C. maenas showed mass occurrences since the early 2000s. Spearman correlation analysis revealed significant correlations of temperature and abundance data of some characteristic species. Statistical downscaling analysis revealed significant correlations between observations and climate indicators such as the North Sea Environmental (NSE) Index for spring. Thus, it appears that climate effects influenced the long-term variability of species number and abundance of epibenthic and demersal fish species in the Jade area, resulting in community shifts in the late 1980s and early 2000s.

Terrestrial and Marine Foraging Strategies of an Opportunistic Seabird Species Breeding in the Wadden Sea.

Lesser black-backed gulls Larus fuscus are considered to be mainly pelagic. We assessed the importance of different landscape elements (open sea, tidal flats and inland) by comparing marine and terrestrial foraging behaviours in lesser black-backed gulls breeding along the coast of the southern North Sea. We attached GPS data loggers to eight incubating birds and collected information on diet and habitat use. The loggers recorded data for 10–19 days to allow flight-path reconstruction. Lesser black-backed gulls foraged in both offshore and inland areas, but rarely on tidal flats. Targets and directions were similar among all eight individuals. Foraging trips (n = 108) lasted 0.5–26.4 h (mean 8.7 h), and ranges varied from 3.0–79.9 km (mean 30.9 km). The total distance travelled per foraging trip ranged from 7.5–333.6 km (mean 97.9 km). Trips out to sea were significantly more variable in all parameters than inland trips. Presence in inland areas was closely associated with daylight, whereas trips to sea occurred at day and night, but mostly at night. The most common items in pellets were grass (48%), insects (38%), fish (28%), litter (26%) and earthworms (20%). There was a significant relationship between the carbon and nitrogen isotope signals in blood and the proportional time each individual spent foraging at sea/land. On land, gulls preferentially foraged on bare ground, with significantly higher use of potato fields and significantly less use of grassland. The flight patterns of lesser black-backed gulls at sea overlapped with fishing-vessel distribution, including small beam trawlers fishing for shrimps in coastal waters close to the colony and large beam-trawlers fishing for flatfish at greater distances. Our data show that individuals made intensive use of the anthropogenic landscape and seascape, indicating that lesser black-backed gulls are not a predominantly marine species during the incubation period.

Deep-sea fishes from Senghor Seamount and the adjacent abyssal plain (Eastern Central Atlantic)

Senghor Seamount is an important fishing ground around the Cape Verde archipelago in the Eastern Central Atlantic. On an experimental field survey in October 2009 and December 2011, a total of 115 deep-sea fishes of 26 species belonging to 18 families were caught on the seamount summit, along the slopes and on the adjacent abyssal plane, using longlines, fish traps, beam trawl and otter trawl. Here we report seven new records for the Cape Verde deep-sea fish fauna. Most species are known from other areas of the Atlantic Ocean, but our findings are an important contribution to our understanding of the distribution of deep-water fish species. The co-occurrence of northern and southern Atlantic ichthyofauna components at Senghor Seamount, and the Cape Verde area in general, can be attributed to the large-scale hydrographic regime with two water masses merging at the Cape Verde Frontal Zone, the North Atlantic Central Water and the South Atlantic Central Water.

Assessment of Fish Assemblages Before Dredging of the Shipping Channel Near the Mouth of the Savannah River in Coastal Georgia

Evaluating the effects of anthropogenic activities is dependent upon data collection prior to impact, though funds are rarely allocated to conduct an assessment before a critical need arises. The Savannah Harbor Expansion Project is one such activity that includes dredging of the Savannah River. It may potentially change physical conditions of the estuary thereby altering fish assemblages. The purpose of the present study was to characterize pre-impact fish assemblages along a salinity gradient near the mouth of the river and determine which abiotic factors most influence them. One site within the mouth of the Savannah River and two sites immediately outside the river mouth were sampled monthly for 2 years using both a beam trawl and seine net. Salinity, temperature, dissolved oxygen, and sediment grain size were assessed. All four factors had a significant effect on fish assemblages. A total of 3943 fishes representing ≥55 species formed three statistically distinct fish assemblages and at least three seasonal assemblages. Only 24 species (43.6 %) were collected by both gear types indicating the importance of using multiple gear types to assess fish assemblages. We conclude that the fish assemblages near the mouth of the Savannah River may be altered or may shift given the predicted increase in salinity and/or the possible changes in sediment composition from channel dredging. Understanding the abiotic factors that most influence spatial and seasonal fish distributions prior to dredging will be invaluable in predicting how organisms will be impacted by similar public projects elsewhere.

Reducing bycatch in beam trawls and electrotrawls with (electrified) benthos release panels

Abstract Benthos release panels (BRPs) are known for their capacity to release large amounts of unwanted benthos and debris, which can decrease mortality on these animals and eases the on board sorting process aboard demersal beam trawlers. They can reduce the bycatch of undersized fish, which is desired once the European discard ban is implemented. However, unacceptable commercial losses of sole (Solea solea L.) and damage to the BRP as a consequence of suboptimal and unsuitable rigging in the traditional beam trawl with chain mat, is hampering a successful introduction in commercial beam-trawl fisheries. To eliminate these drawbacks, square-meshed BRPs with different mesh sizes (150, 200, and 240 mm) were rigged in a trawl with square net design as used in electrotrawls and tested for selectivity. In addition to this, the effect of electric stimulation at the height of the BRP to eliminate the loss of commercial sole was examined. According to our observations, no abrasion of the net attributable to suboptimal rigging occurred in any of the BRPs tested. The catch comparisons showed significant release of benthos and undersized fish in all panel mesh sizes, but there was always a significant loss of marketable sole in the 150, 200, and 240 mm BRPs. Adding a 80 Hz electric cramp stimulus to the BRP, resulted in equal catches of sole larger than 25 cm as the standard net, without negatively affecting the release of benthos and most undersized commercial fish. This clearly demonstrates the promising potential of electrified BRPs (eBRPs), but further optimization by using smaller BRP mesh sizes or optimized electric stimuli is warranted to retain all marketable sole.

Length-weight relationships of five commercial fish species from the Strait of Hormuz in the Persian Gulf

Length-weight relationships are described for five fish species from the coast of the Hormuz Strait in the Persian Gulf, Iran. Specimens were collected between August 2010 and July 2011 using shrimp beam trawls, gill nets and intertidal fishing weirs. Relationships for three of the species had no previous data in the international science global databank on fishes: www.FishBase.org. A new maximum length was recorded for Acanthopagrus latus.

Distribution of skates and sharks in the North Sea: 112 years of change

How have North Sea skate and shark assemblages changed since the early 20th century when bottom trawling became widespread, whilst their environment became increasingly impacted by fishing, climate change, habitat degradation and other anthropogenic pressures? This article examines long-term changes in the distribution and occurrence of the elasmobranch assemblage of the southern North Sea, based on extensive historical time series (1902-2013) of fishery-independent survey data. In general, larger species (thornback ray, tope, spurdog) exhibited long-term declines, and the largest (common skate complex) became locally extirpated (as did angelshark). Smaller species increased (spotted and starry ray, lesser-spotted dogfish) as did smooth-hound, likely benefiting from greater resilience to fishing and/or climate change. This indicates a fundamental shift from historical dominance of larger, commercially valuable species to current prevalence of smaller, more productive species often of low commercial value. In recent years, however, some trends have reversed, with the (cold-water associated) starry ray now declining and thornback ray increasing. This shift may be attributed to (i) fishing, including mechanised beam trawling introduced in the 1960s-1970s, and historical target fisheries for elasmobranchs; (ii) climate change, currently favouring warm-water above cold-water species; and (iii) habitat loss, including potential degradation of coastal and outer estuarine nursery habitats. The same anthropogenic pressures, here documented to have impacted North Sea elasmobranchs over the past century, are likewise impacting shelf seas worldwide and may increase in the future; therefore, parallel changes in elasmobranch communities in other regions are to be expected.

The response of the North Sea demersal fish community to changing fishing pressure as seen through the prism of the large fish indicator

The large fish indicator (LFI) is a size-based indicator of fish community state. In the North Sea, the LFI is already established as the fish community’s Ecological Quality Objective (OSPAR-EcoQO). The LFI has also been proposed as an indicator for food webs and for monitoring of biodiversity in European regional seas. The LFI was developed based on the entire North Sea fish community, which ignores the differences between the southern and the northern fish communities from the International Bottom Trawl Survey (IBTS) data. In this study, we have calculated LFIs based on IBTS and the Beam Trawl Survey (BTS), which target different components of the fish community and we test whether the LFI responds to changes in fishing pressure. The results did not confirm our expectation of a negative correlation between the pressure and state. We found a positive relationship between the IBTS-based LFI and the roundfish fishing mortality as well as an inverse relationship between the BTS-based LFI and the flatfish fishing mortality. The differences in the relationships between the IBTS- and BTS-based LFI and the respective roundfish-averaged and flatfish-averaged fishing mortality confirmed the spatial differences between the North Sea roundfish and flatfish fish communities. Although previous relationships between the LFI and the fishing pressure involved lengthy time-lags (10–12 years), we found shorter responsiveness of the LFI of 1–2 years. Further understanding of the ecological, environmental and anthropogenic factors affecting the LFI is required before ecosystem objectives can be set within the MSFD.

Ecology of nonnative Siberian prawn (Palaemon modestus) in the lower Snake River, Washington, USA

We assessed the abundance, distribution, and ecology of the nonnative Siberian prawn Palaemon modestus in the lower Snake River, Washington, USA. Analysis of prawn passage abundance at three Snake River dams showed that populations are growing at exponential rates, especially at Little Goose Dam where over 464,000 prawns were collected in 2015. Monthly beam trawling during 2011–2013 provided information on prawn abundance and distribution in Lower Granite and Little Goose Reservoirs. Zero-inflated regression predicted that the probability of prawn presence increased with decreasing water velocity and increasing depth. Negative binomial models predicted higher catch rates of prawns in deeper water and in closer proximity to dams. Temporally, prawn densities decreased slightly in the summer, likely due to the mortality of older individuals, and then increased in autumn and winter with the emergence and recruitment of young of the year. Seasonal length frequencies showed that distinct juvenile and adult size classes exist throughout the year, suggesting prawns live from 1 to 2 years and may be able to reproduce multiple times during their life. Most juvenile prawns become reproductive adults in 1 year, and peak reproduction occurs from late July through October. Mean fecundity (189 eggs) and reproductive output (11.9 %) are similar to that in their native range. The current use of deep habitats by prawns likely makes them unavailable to most predators in the reservoirs. The distribution and role of Siberian prawns in the lower Snake River food web will probably continue to change as the population grows and warrants continued monitoring and investigation.

Fish density and target strength distribution of single fish echoes in varying light conditions with single and split beam echosounding and trawling

To evaluate the consistency of mobile and vertical echosounding results from the 1980s to the 2000s, fish density (fish ha−1) and target strength (TS, dB) estimates of single (70 and 200 kHz) and split (38 and 120 kHz) beam echo sounders were compared under varying light conditions. Acoustic estimates were compared with trawling results. During daytime hauls, the catch per swept area (CSA) of vendace and smelt were high at 10–15 m depth and low at 15–30 m depth. Around sunset, vendace and to some degree also smelt were concentrated at some meters above the thermocline. Around midnight, the CSA showed that smelt occupied higher water layers than vendace. Under different light conditions, both single and split beam echo sounders were in good agreement regarding the general level of fish density. In dusk and darkness, density estimates from echosounding and trawling as well as the TS-distribution between the single and split beam sounders were more consistent than those in daylight. We conclude that in boreal lakes single and split beam echosoundings outline, in comparable light conditions, consistent time series from the 1980s up to the year 2010. Darkness gives the best condition for estimating fish density and acoustic fish size.

Population dynamics of Philocheras trispinosus (Crangonidae) with abundance of other caridean shrimps (Crustacea: Decapoda) caught by beam trawl in the Southern Black Sea, Turkey

Objective: To determine growth and reproduction biology of Philocheras trispinosus (P. trispinosus) with abundance of other caridean shrimps caught by beam trawl in the Southern Black Sea. Methods: Samplings were carried out monthly with a beam trawl of 2 m length and 15 mm cod-end mesh size between December 2012 and November 2013. All individuals were sampled between 1 and 40+ m water depth from 146 hauls. Results: A total of 550 P. trispinosus, 618 Palaemon adspersus, 12 Palaemon serratus, 11 Philocheras fasciatus and 10 Crangon crangon were sampled during the study period. The crangonid shrimps started appearing during the winter and spring and the number of individuals increased to reach their highest value in mid-winter and mid-spring. The seasonal von Bertalanffy growth parameters for P. trispinosus were estimated as L∞ = 29.3 mm total length, K = 0.860/year, t0 = –0.900 year, C = 0.180, and ts = 0.010. The start of the slow growth period was at the beginning of July (WP = 0.510). Ovigerous females appeared in the sampling area between January and April. Size at sexual maturity was estimated as 25.69 mm total length. Conclusions: The results supported the distribution and abundance of caridean shrimp species from the study area and the population dynamics of the most abundant shrimp species, P. trispinosus. The current study can be answered as baseline data prior to management strategies to ensure sustainable conservation of the shrimp species.

Temperature-Dependent Growth of Early Juvenile Southern Tanner CrabChionoecetes bairdi: Implications for Cold Pool Effects and Climate Change in the Southeastern Bering Sea

Temperature strongly influences the growth of crustaceans and directly controls distribution. Despite being commercially important, there are no data on temperature effects upon growth in newly settled southern Tanner crab Chionoecetes bairdi. Recently settled crabs were reared through three consecutive molts, both individually and in groups, at four different temperatures; 2°C, 6°C, 9°C, and 12°C. Survival was higher for crabs grown individually (92%) than those in groups (66%) owing to cannibalism, particularly during molting. There were no temperature effects on survival. Growth rate (mm/day) increased linearly with temperature, a product of exponential decline in intermolt period with increasing temperature and amolt increment that was relatively constant across temperatures. Growth rate, intermolt period, and growth increment did not differ between crabs grown singly or in groups. These data suggest that growth in 0 y aged southern Tanner crabs is strongly inhibited at temperatures less than 2°C. A small mesh beam trawl survey was conducted in the southeast Bering Sea during September 2012, a year when a cold pool (<2°C bottom water) dominated the middle shelf. Southern Tanner crab less than 12 mm (carapace width) were concentrated just north of the Alaska Peninsula and along the outer shelf where bottom water was more than 2°C, but largely absent from the middle shelf. In contrast, adult southern Tanner crabs were widely distributed across the middle and outer shelves. It was hypothesized that early juvenile southern Tanner growth is inhibited by cold pool conditions, prolonging vulnerability to predation, and reducing survival. In the future, if sea temperature rises and sea ice is diminished, less frequent and less intense cold pool events may lead to increased persistence of thermally suitable juvenile southern Tanner crab habitat across the southeastern Bering Sea middle shelf region.

Assessing fishery and ecological consequences of alternate management options for multispecies fisheries

AbstractDemands for management advice on mixed and multispecies fisheries pose many challenges, further complicated by corresponding requests for advice on the environmental impacts of alternate management options. Here, we develop, and apply to North Sea fisheries, a method for collectively assessing the effects of, and interplay between, technical interactions, multispecies interactions, and the environmental effects of fishing. Ecological interactions involving 21 species are characterized with an ensemble of 188 plausible parameterizations of size-based multispecies models, and four fleets (beam trawl, otter trawl, industrial, and pelagic) characterized with catch composition data. We use the method to evaluate biomass and economic yields, alongside the risk of stock depletion and changes in the value of community indicators, for 10 000 alternate fishing scenarios (combinations of rates of fishing mortality F and fleet configuration) and present the risk vs. reward trade-offs. Technical and multispecies interactions linked to the beam and otter trawl fleets were predicted to have the strongest effects on fisheries yield and value, risk of stock collapse and fish community indicators. Increasing beam trawl effort led to greater increases in beam trawl yield when otter trawl effort was low. If otter trawl effort was high, increases in beam trawl effort led to reduced overall yield. Given the high value of demersal species, permutations of fleet effort leading to high total yield (generated primarily by pelagic species) were not the same as permutations leading to high catch values. A transition from F for 1990 to 2010 to FMSY, but without changes in fleet configuration, reduced risk of stock collapse without affecting long-term weight or value of yield. Our approach directly addresses the need for assessment methods that treat mixed and multispecies issues collectively, address uncertainty, and take account of trade-offs between weight and value of yield, state of stocks and state of the environment.

Competitive interactions between two fishing fleets in the North Sea

Abstract We examine whether the landing rates of Belgian beam trawlers in the Southern Bight of the North Sea were affected through competitive interactions with the Dutch beam trawler fleet and whether the development of a pulse trawler fleet has altered competitive interactions between both fleets. Effects of competition were investigated through a natural experiment based on the different weekly exploitation patterns of both fleets. Logbook data were used to fit a generalized additive mixed model for the daily landing rates of the target species sole (Solea solea) and plaice (Pleuronectes platessa). Results showed that landing rates of sole by the Belgian beam trawlers (&amp;gt;221 kW) from 2006 to 2013 were lower during weekdays than during weekends when the Dutch trawler fleet is in harbour, while no such an effect was found for plaice. After the development of a pulse trawler fleet in 2011, the negative weekday effect in the sole landing rates was much more pronounced in 2012 and 2013. This increased loss of efficiency during weekdays, as a result of increased competition with the Dutch trawler fleet, coincided with a reallocation of fishing effort by the Belgian beam trawler fleet.

Short-term effects of fishery exclusion in offshore wind farms on macrofaunal communities in the Belgian part of the North Sea

With the wide scale construction of offshore wind farms (OWFs) throughout the entire North Sea, large areas are permanently being closed to beam trawl fisheries. Beam trawling has affected macrobenthic assemblages for centuries, especially the fragile and long-lived species. Due to the prohibition of bean trawling in many OWFs, opportunities are being provided to investigate the potential recovery of vulnerable species and the creation of de-facto Marine Protected Areas (MPAs). The soft-substrate macrobenthic community was investigated from 2008 to 2012, before and after the construction of an OWF in the Belgian part of the North Sea, situated on the Bligh Bank. The fishery enclosed area (±21km2) within the OWF (No Fishery area) was compared with a surrounding control area (±30km2) where regular fishing activities were registered through vessel monitoring system (VMS) data throughout the period 2010–2011. Three years after the exclusion of beam trawl fisheries, subtle changes within the macrobenthic community were observed in the No Fishery area. The benthic mysid shrimp Gastrosaccus spinifer (30±15indm−2), tube-building polychaetes Terebellidae sp. (196±151indm−2) and the echinoderm Echinocyamus pusillus (73±71indm−2), sensitive to trawling activities, showed increased abundances within the No Fishery area. With an expansion of the wind farm concession area to 238km2 in the future, the likely increase of dense Terebellidae patches (e.g., Lanice conchilega reefs) within the No Fishery area could create an ecological important large-scale refugium for higher trophic levels. This study creates a baseline for the evaluation of long-term changes due to the fishing impacts and effects related to the presence of OWFs and highlights the importance of executing long-term monitoring programs in combination with targeted research.

서해 군산 연안에서 새우조망으로 어획된 저서생물의 종조성 및 군집구조

Abstract Species composition of aquatic organism in the marine ranching area of Gunsan, Korea were investigated using shrimp beam trawl from May to December in 2010. A total of 91 species, 98,127 ind./ ㎢ and 877.6 ㎏/㎢ of aquatic organism were collected. Among them, species were included 60 species in Pisces, 21 in Crustacea and 10 in Mollusca. The individual dominant species, occupying over 10% of total individuals, were Latreutes anoplonyx(47,327 ind/㎢, 48.23%), Crangon hakodatei(11,578 ind./㎢, 11.80%) and Trachysalambria curvirostris(10,237 ind./㎢, 10.40%). And the biomass dominant species, occupying over 9% of total biomass, were Paralichthys olivaceus(135 ㎏/㎢, 15.4%), Okamejei kenojei(98.2 ㎏/㎢, 11.2%) and Portunus tribuberculatus(84.8 ㎏/㎢, 9.6%). From the cluster and MDS analysis based on Bray-Curtis similarity matrix of fourth root transformed data of number of species and individuals per unit area collected more than two times during this survey by each month and station was divided into three different groups. Group A showed seasonal similarity of characteristic of distribution in August and November, Group B in December and Group C in May. Key words : Species composition, Community structure, Dermersal organisms, Gunsan, Shrimp beam trawlCorresponding author : 051-626-9895, bluejuve@gmail.com 2016 (R2016051) .