Species Composition Of Catches Research Articles

Comparative Study on Current Fishing Status of Paalameenmadu and Kallar Barmouths in Batticaloa District,

Batticaloa lagoon is one of the productive estuaries on the East coast of Sri Lanka and is connected to the sea at two points, Paalameenmadu and Kallar barmouths. The entire dynamics of the lagoon is based on the seasonal opening and closing of the above barmouths which influences the fish catch composition in nearby fishing areas. This study collects information on current fishing practices, species composition of the catch, and seasonal catch species composition, the level of awareness on fishing regulation and sustainable fishery using semi-structured questionnaire. Fisheries data were collected from 10 major barmouth fishery landing sites from January to April 2021. 210 respondents were selected using a stratified random sampling technique. A semi-structured questionnaire was used to collect responses after a pre-test and analysed with descriptive statistics method using SPSS. The study revealed that Paalameenmadu barmouth was opened annually and Kallar barmouth has been closed for the last five years. The most practiced crafts in Paalameenmadu are outboard Fiber Reinforced Plastic boats (OFRP) by 35.26% of fishers and small lagoon canoes by 87.04% fishers in Kallar. A total of seven types of fishing gears are used, among them hook and line, cast net, and dragnet were identified as major fishing gears operated. 30 aquatic species have been recorded in the catch, representing 17 families. Among them, dominant fish families are Scombridae 17.11% and Penaeidae 14.81% in Paalameenmadu. In the Kallar, family Penaeidae 18.75% and Gerreidae 16.32% have been recorded. Barmouth opening is favourable for fishing and 38.57% Penaeidae species were caught during barmouth opening period. Community response that Irregular and early barmouth opening have caused a reduction in fish production which impacts on economic activities. Fishermen have good awareness on importance of fishery resources sustainability and these resources need to be preserved for future generations through proper management practices.

Patterns of variability of species composition of catches from the russian fishing vessels in the south-eastern Pacific ocean for 2015–2022

The work provides information on the patterns of species composition of catches from the Russian fishing vessels conducted fishing of jack mackerel (Trachurus murphyi Nichols 1920), chub mackerel (Scomber japonicus Houttuyn 1782) and redbait (Emmelichthys spp.) in the South-Eastern Pacific Ocean outside the economic zones of the coastal States. According to scientific observations, an analysis of the composition of species caught by the Russian fishing vessels is given. When fishing in the pelagic zone over ocean depths, jack mackerel was the main target species, chub mackerel formed the bycatch. At the same time, the proportion of chub mackerel in catches in the northern parts was higher than in the southern ones. When fishing on seamounts of the Nazca Ridge, catches were dominated by redbait with jack mackerel and alfonsino (Beryx splendens Lowe, 1834) as bycatch. According to the similarity of the species composition of catches, three areas – 1) all the Southern and Central subareas and part of the Northern subarea; 2) seamounts of Nazca ridge; 3) part of the Northern subarea near the border of the EEZ of Peru between 17–20°S, were singled out using the cluster analysis method.

Size at sexual maturity, seasonal variation by maturity stages, and fecundity of the spotted round ray (Urobatis maculatus) and the thorny stingray (Urotrygon rogersi) from the northern tropical eastern Pacific.

Round rays (family: Urotrygonidae) are commonly caught as by-catch by shrimp trawl fisheries in the tropical eastern Pacific (TEP). However, little information on their life history and catch species composition exists for most round ray species, preventing the evaluation of the impact of fishing on their populations. The mean size at sexual maturity (DW50 ), seasonal variation by maturity stages, and fecundity for two round ray species caught during shrimp trawl research cruises in the south-eastern Gulf of California (northern TEP) were estimated using a multi-model approach and inference for the first time, to determine the part of the population of each species that is being affected by shrimp trawling. Disc width (DW) ranged from 7.0 to 30.9 cm for the spotted round ray (Urobatis maculatus), and 7.2-33.5 cm for the thorny stingray (Urotrygon rogersi), with females reaching larger sizes than males in both species. The DW50 was estimated at 12.8 and 11.8 cm DW for the males and females of U. maculatus, respectively, whereas for U.rogersi, it was 15.0 and 18.4 cm DW for males and females, respectively. Embryos were found in females ≥14.5 cm DW in both species. The maximum fecundity was five embryos for U. maculatus (mean = 3.1 ± 0.2 S.E., mode = 4), and six embryos for U. rogersi (mean = 3.0 ± 0.3 S.E., mode = 2). Fecundity and embryo size did not vary with maternal size. Male and female immature and mature individuals for both species, including pregnant females, were found in the catches in all seasons of the year. Our results can help determine the vulnerability of the studied species populations to fishing pressure from shrimp trawling in the northern TEP and guide the development of future monitoring strategies and conservation actions for these species, if necessary.

Assessment of amateur fishing and its impact on the state of stocks of aquatic biological resources on the Ob river and its tributaries (Chulym, Tom) within the boundaries of the Tomsk region

Amateur fishing is one of the types of activities for the extraction (catch) of aquatic biological resources, which affects their stocks. As part of the state task, VNIRO conducts annual monitoring of amateur fishing and analyzes its impact on the state of aquatic life stocks. The paper presents the seasonal results of observations for the period from September 2022 to August 2023, including: the number of days suitable for amateur fishing, the number of amateur fishermen, the species composition of catches and an estimate of the volume of their catch. An assessment of the impact of amateur fishing on the stocks of aquatic biological resources is presented. The largest quantitative catch falls on pike (18.2%), perch (17.9%), roach (11.3%), ide (11.1%), and also, mainly on the Tom — Yelets river (16.1%), and in the mass unit of measurement — on pike, accounting for 50.7% of the total catch weight in year. The largest number of amateur fishermen and the volume of fish caught by them falls on the summer and autumn periods. In the autumn period, pike is caught better than at other times of the year, and more experienced amateur anglers come to such fishing. The seasons of the year are also significantly different in terms of the average number of amateur fishermen per day and the duration of fishing, there are the least number of winter fishing enthusiasts, which is due to weather conditions and meager catches. In spring, the average number of amateur fishermen per day increases by 2.5 times, and in summer it is already 6.5 times more than in winter. The average duration of fishing also increases from the winter period (2 hours) to the summer (6 hours). In general, the impact of amateur fishing on aquatic biological resources is assessed as weak, but there is pressure on certain species that are in the greatest consumer demand.

Methodological aspects of assessing the scale of IUU fishing in inland water bodies by the example of individual regions of Russia

Purpose of work: comparative analysis of the available methodological approaches to the assessment of the amount of commercial fish species taken by IUU fishing and IUU bycatch in the implementation of fisheries on the example of individual regions of the Russian Federation, including inland water bodies of different fishery basins. Methods used: comparative analysis of methodological materials on assessment of IUU fishing, used in different branches of VNIRO. Novelty: for the first time an analysis of various methods for assessing the extraction of commercial fish species by IUU fishing has been conducted; the presented generalized data on the assessment of illegal catches in different fishery basins of the Russian Federation show that the amount of IUU fishing is the volume which often exceeds the values of the total allowable catches (TAC) and the recommended volumes of production (catch) of aquatic bioresources. Practical significance: Refinement of methodical approaches of estimation of IUU fishing and IUU bycatch will allow receiving a characteristic picture of size of IUU fishing for various fishery basins taking into account specifics of fishery basins, species composition of catches and applied gears of catch. The resulting data on the value of IUU-catch of commercial fish species will be used to clarify (adjust) the projected volume of production (catch) of commercial fish in Russia.

Changes in size and species composition Russian catches in the XXI century by example South Seas and the Yuzhno-Kurilsky fishery district

The role of the southern seas of Russia and the South Kuril zone of the Far Eastern Basin in domestic fishery is shown. Changes in the size and species composition of catches are characterized. The period from 2001 to 2022 is taken for the study. Assumptions are made about the prospects of Russian fishery in the coming years.

Evolution of catches and specific composition of elasmobranchs in Mauritanian artisanal, coastal and offshore fisheries

Elasmobranchs are among the most vulnerable marine fish and the most impacted by fishing. In Mauritania, although many management and prohibition measures have been introduced, this taxonomic group continues to be caught and landed. To follow trends of catches and catch species composition by the different fishing fleets in Mauritania we used the data from the fisheries monitoring system set up by the Mauritanian Institute of Oceanographic Research and Fisheries (IMROP) collected since 2006 in the National Park of Banc d′Arguin (PNBA). These data are supplemented by the monitoring data on the artisanal, coastal, and deep-sea fisheries, and the data from the scientific demersal trawling campaigns in the Mauritanian Exclusive Economic Zone (EEZ) that IMROP has been conducting since 1982. The results show that elasmobranch catches are highest in the artisanal and coastal fisheries, particularly in the PNBA, where several conservation measures for these species have been put in place. These results suggest that there is a need to strengthen the implementation of the shark management plan by a strict application of the prohibition of gear targeting these species.

Современное состояние рыболовства в Волго-Каспийском подрайоне

Analysis of the current state of fisheries in the Volga-Caspian subarea has been carried out. The processes 
 of deformation of aquatic biological resources of the Caspian basin have been assessed. Modern catches of commercial fish have decreased by one order of magnitude compared to the last century. At the beginning of the 20th century the stocks of semi-anadromous and river fish species were significant, the catches reached 200-300 thousand tons. In recent years, the catch of the fish has stabilized at the level of 36.0-43.3 thousand tons. In recent years the catches of vobla, carp and zander were the lowest in the history of the Caspian fisheries. The catch of carp, compared with that in the 1980s, decreased by more than 5 times, vobla – by 6 times, zander – by 4 times. Since 2003, there has been a decrease in the catch of bream up to 7-10 thousand tons. A sharp decrease in catches is primarily explained by the collapse of kilka stocks. There is an acute problem of limiting and even a complete ban on fishing vobla. According to the results of the correlation analysis (comparison of the values of natural factors with the value of catches in the studied subareas), it was found that fish production in the Volga-Caspian subarea does not show any relationship with any of the listed natural factors. An analysis of the species composition of semi-anadromous and river fish caught by various fishing gear in the Lower Volga was carried out. The species composition of catches by secrets is more diverse than by cast nets and gillnets. Most abundant species in the catches are bream, vobla, pike, catfish, rudd. A forecast is given for a further fishery reduction in the Caspian basin including the Astrakhan region.

Знаряддя любительського рибальства на Каховському водосховищі

Purpose. Determination of the main fishing gears used by recreational fishermen on the Kakhovka Reservoir and their place in the general system of fishing gears according to their functional and structural features. Methodology. The work is based on the materials obtained during 2003-2022 on the Kakhovka Reservoir. Collection and processing of information was carried out on the basis of unified and adapted existing methods of research of recreational fishing by direct creel survey, survey of recreational fishing, interviewing recreational fishermen at the place of fishing and observation. Analysis of ichthyological material was carried out according to generally accepted basic methods. Statistical data processing was carried out in MS Excel. Findings. The most popular fishing gears used by recreational fishermen on the Kakhovka Reservoir were identified: summer float rods, bottom rods, winter fishing rods and spinning rods. Their place in the general system of fishing gears as well as functional and structural components were defined. Peculiarities of the use of fishing rods of various types and the species composition of catches were given, an assessment of compliance with the requirements of the current Fishing Rules regarding equipment and fishing methods was provided. Originality. The study is a first assessment of recreational fishing gears and methods as well as the peculiarities of their use on the Kakhovka Reservoir. Practical value. Based on the systematization of current information on the classification and design features of gears used by recreational fishermen, unified approaches for their definition in scientific research and legislation were proposed. Key words: Kakhovka reservoir, amateur fishing, recreational fishing, fishing gears, catch size structure.

Fishing under climate change: Dynamics of composition and structure of catches in the Russian Black Sea in the XXI century

Currently, the Black Sea ecosystem is undergoing significant changes, and that affects the dynamics of the species composition of catches. The main reasons for the change in the Black Sea ichthyofauna are considered to be: fishing, anthropogenic water pollution, invasion of new species, and the effect of large-scale climatic and related oceanological and hydrological processes on the productivity characteristics of commercial Black Sea fish. With no understanding the patterns of the effect of these factors on ichthyofauna, it is impossible to rationally use bioresources and protect nature. The aim of the work was to study the effect of climate warming on the species composition and structure of catches in the Russian Black Sea in the XXI century. The authors had used: the results of own ichthyological observations; data published on the composition of the Black Sea catches; and the information available on the official websites of the Ministry of Agriculture of the Russian Federation, the Federal Agency for Fishery, and its Sea of Azov – Black Sea Territorial Administration. The analysis of the possible effect of global warming on the results of fishing in the Russian Black Sea was carried out. It is shown that in the XXI century, the ratio of thermophilic fish, which spawn in the summer, increased; those species are European anchovy Engraulis encrasicolus (Linnaeus, 1758), red mullet Mullus barbatus Linnaeus, 1758, and horse mackerel Trachurus mediterraneus (Steindachner, 1868). As established, the dynamics of the ichthyofauna in the area is determined by at least four processes related to water warming: improvement of reproduction conditions and increased survival of eggs and juveniles of thermophilic species; change in the intraspecific structure; invasion and naturalization of Mediterranean species with the subsequent change in the food relationships within the ecosystem; and concentration of psychrophilic species at greater depths. The need for a thorough study of this issue is concluded, aimed at long-term forecasting of the raw material base state of the fishing industry in the Russian Black Sea.

Biological aspects of sharks landed in the Fishing Port of Kutaraja, Banda Aceh, Indonesia

Shark fisheries in Aceh are not supported by the availability of research-based data and information that needed to support the preservation and development of this resource. The purposes of the study were to assess the biological aspects including shark species identify and their status in IUCN, length distribution, sex ratio, and maturity stage of male shark. This study was conducted from August to October 2017 in the Fishing Port of Kutaraja, Banda Aceh. The observation survey of fish landing sites was conducted to collect the catch species composition, total length of each individual, sex, and maturity stage of male genital of shark (clasper). The results showed there are 17 species of sharks caught by some fishing gears (n = 318). Mean total length, fork length, and standard length are 122.90 cm, 110.77 cm, and 86.50 cm, respectively. The sex ratio of dominated species (Carcharhinus sorrah, Sphyrna lewini, and Alopias pelagicus) showed not significantly difference between males and females, based on Chi-square test. The percentage of male shark maturity for each category (NC, NFC, FC) is 52%, 13%, and 35%, respectively. The percentage of the IUCN status (threatened rare, threatened with extinction, and almost threatened) of collected species are 12%, 29%, and 41%, respectively.

A methodological framework for characterizing fish swimming and escapement behaviors in trawls.

Knowledge about fish behavior is crucial to be able to influence the capture process and catch species composition. The rapid expansion of the use of underwater cameras has facilitated unprecedented opportunities for studying the behavior of species interacting with fishing gears in their natural environment. This technological advance would greatly benefit from the parallel development of dedicated methodologies accounting for right-censored observations and variable observation periods between individuals related to instrumental, environmental and behavioral events. In this paper we proposed a methodological framework, based on a parametric Weibull mixture model, to describe the process of escapement attempts through time, test effects of covariates and estimate the probability that a fish will attempt to escape. We additionally proposed to better examine the escapement process at the individual level with regard to the temporal dynamics of escapement over time. Our approach was used to analyze gadoids swimming and escapement behaviors collected using a video set up in front of a selective device known to improve selectivity on gadoids in the extension of a bottom trawl. Comparison of the fit of models indicates that i) the instantaneous rate of escape attempts is constant over time and that the escapement process can be modelled using an exponential law; ii) the mean time before attempting to escape increases with the increasing number of attempts; iii) more than 80% of the gadoids attempted to escape through the selective device; and iv) the estimated probability of success was around 15%. Effects of covariates on the probability of success were investigated using binomial regression but none of them were significant. The data set collected is insufficient to make general statements, and further observations are required to properly investigate the effect of intrinsic and extrinsic factors governing gadoids behavior in trawls. This methodology could be used to better characterize the underlying behavioral process of fish in other parts of a bottom trawl or in relation to other fishing gears.

Perbandingan Produktivitas Pancing Ulur (HandLine) Dan Jaring Insang (Gill net) Nelayan Desa Kusamba, Klungkung, Bali Terhadap Hasil Tangkapan Ikan Tongkol (Auxis sp.)

This study uses two environmentally friendly fishing gears namely gill net and hand line. The length of one set of hand line is 100 m and the length of one set of gill nets is 250 m. The purpose of this study was to determine the number of catches, species composition of catches and the efficiency of fishing gear that provided benefits for the fishermen of Kusamba Village. This data collection was carried out in field plunge directly with fishermen using the one day trip method for 35 trips during the tuna fishing season by Kusamba Village fishermen. Auxis sp is one type of fish that is the main target of the catch of fishermen in Kusamba Village. Auxis sp often follows the current circulation, the catch of Auxis sp on the fishermen of Kusamba Village has a different amount of production every day. In terms of Auxis sp catches by Kusamba Village Fishermen who use two fishing gear are dominated by gill nets and the quality aspect is dominated by hand linecatches. It is known that there are two types of tuna, namely Auxis rochei and Auxis thazard. The catch is in principle the output of fishing activities, while the effort needed in principle is an input from the fishing activities, fisheries production in an area has increased or decreased can be seen from the results of CPUE. The highest CPUE value of gill nets is 53.75 tails / effort, the highest CPUE value of hand line is 75 tails / effort.

Karadeniz’in Güney-doğu Kıyılarında Yapılan Galsama Ağları ile Avcılıkta Av Kompzisyonu ve Iskarta Oranı Üzerine Mevsim ve Derinliğin Etkisi

Effects of depth and season on species composition of catch and discard rate in the gillnet fishery on the south-eastern coast of the Black Sea was investigated in this study. for this purpose, fishing trials were carried out in the four different depth strata (0-14 m, 15-29 m, 30-49 m and 50 m≥) using multifilament gilnets with mesh sizes of 32, 34, 36 and 38 mm, from March 2013 to February 2014. In the fishing trials, a total of 2506 individuals (133.729 g) belongs to eight fish species were obtained which were whiting (Merlangius merlangus), red mullet (Mullus barbatus), pontic shad (Alosa immaculata), mediterranean horse mackerel (Trachurus mediterraneus), black scorpionfish (Scorpoena porcus), stargazer (Urascopus scaber), seahorse (Hippocampus sp.) and black-striped pipefish (Syngnathus abaster). Allmost catches for whiting, red mullet, pontic shad and mediterranean horse mackerel were of economic value, while all catches for the other species were were discarded. In the shallow waters varying between 0-14 m depth, red mullet and mediterranean horse mackerel were mostly caught. However, catches of especially mediterranean horse mackerel were decreased gradually with increasing water depth. The most caught fish species in deeper water strata more than 15 m was whiting. In the evaluation of the effect of the season on the species composition of catch, the whiting was the most caught fish species by the trial gillnets in all seasons. These fish species, except autumn season (in autumn, potic shad and Mediterranean horse mackerel) followed by red mullet in all seasons. On the orher hand, the rate of discard was determined as 10.2% in number and 15.9% in biomass. It has been found that the discard rate decreases gradually due to the increase in water depth. Seasonally, the lowest discard rate was calculated in winter, followed by autumn, spring and summer, respectively.

Modelling trawling discards of the Alboran fisheries in the Mediterranean Sea

The ecosystem processes underlying the discard rates of the demersal otter-trawl fishery in the Alboran Sea, Western Mediterranean are investigated. We evaluate whether environmental and climatic variability, measured from operational oceanographic data, allow assessment of discarded species abundances. Monthly data collected by onboard fishery observers during 2011 and 2012 in the Northern Alboran Sea served as a case study of the trawling fishery’s dynamics. The study area was split into west and east zones to account for differences in the Atlantic and Mediterranean Sea water influences, for distinct geomorphology and for species composition of catches. Sixteen species divided in three groups were analysed: species without discards, those partially discarded and those completely discarded. Applying Gaussian Generalized Additive Models (GAM), we tested the relationships of standard oceanographic data products and climatic variability with discard abundances. These variables were sea surface temperature (SST) and chlorophyll a (chl-a) from satellite imagery, as indicators of environmental conditions, and the North Atlantic Oscillation index (NAO) as a climatic indicator. Models were applied for target and bycatch species partially discarded. These were the following species: gadoid like European hake (Merluccius merluccius), Blue Whiting (Micromesistius poutassou), Seabreams (Pagellus acarne, and Pagellus erythrinus), and Mackerels (Trachurus mediterraneus, Trachurus picturatus and Trachurus trachurus). Surface seawater temperature was a relevant variable in coastal and eastern, more haline Mediterranean waters. Climatic variability represented by NAO was useful for assessing discard rates in the more productive western zone. Chlorophyll a showed less relevance for discard prediction models, but it was more related in the coastal zones. Including oceanographic data products and climatic patterns in GAM models of fishery discards provides a new perspective that may improve our predictive capabilities for management decisions.

The commercial harvest of ice-associated seals in the Sea of Okhotsk, 1972-1994.

Sealing log books from 75 out of 79 commercial harvest cruises carried out between 1972 and 1994 in the Sea of Okhotsk, Russia, were analyzed to describe spatial and temporal allocation of ice-associated seal harvest effort, species composition of catches, total harvest rates, and related parameters for species including ringed (Pusa hispida), ribbon (Histriophoca fasciata), bearded (Erignathus barbatus) and spotted (Phoca largha) seal. Variations in catch per unit effort were explored in relation to year, sea ice conditions, day of the year, and geographic location. In most years, the harvest was predominantly represented by ringed seals (mean = 0.43, range 0.25–0.67), followed by ribbon (mean = 0.31, range 0.15–0.43), spotted (mean = 0.19, range 0.11–0.35) and bearded seals (mean = 0.07, range 0.03–0.14). The struck-and-lost percentages were as high as 30–35% for ringed, bearded and spotted seals and 15–20% for ribbon seals. Catch per unit effort (number of seals/skiff*day) for ringed, ribbon, and spotted seals had a similar seasonal pattern with a distinct spike in catches for spotted seals in the first week of May, for ribbon seals in the last week of May, and for ringed seals in the second week of June. Catches of bearded seals showed a less pronounced temporal structure with a gradual increase toward the end of the harvest season in the majority of years. Spatial distribution of harvest effort followed closely with seal distribution obtained from aerial surveys. These data could be used as a source of information on seal herd location throughout the breeding and molting seasons and for more complex demographic or life-table models. We did not find any evidence of the decline of catch per unit effort over the study period. Timely introduction of state regulations and efficient harvest management apparently prevented severe depletion of ice-associated seal populations in the Sea of Okhotsk during the periods of their intense exploitation.

The Ecuadorian Artisanal Fishery for Large Pelagics: Species Composition and Spatio-Temporal Dynamics.

The artisanal fisheries of Ecuador operate within one of the most dynamic and productive marine ecosystems of the world. This study investigates the catch composition of the Ecuadorian artisanal fishery for large pelagic fishes, including aspects of its spatio-temporal dynamics. The analyses of this study are based on the most extensive dataset available to date for this fishery: a total of 106,963 trip-landing inspection records collected at its five principal ports during 2008 ‒ 2012. Ecuadorian artisanal fisheries remove a substantial amount of biomass from the upper trophic-level predatory fish community of the eastern tropical Pacific Ocean. It is estimated that at least 135 thousand metric tons (mt) (about 15.5 million fish) were landed in the five principal ports during the study period. The great novelty of Ecuadorian artisanal fisheries is the “oceanic-artisanal” fleet component, which consists of mother-ship (nodriza) boats with their towed fiber-glass skiffs (fibras) operating with pelagic longlines. This fleet has fully expanded into oceanic waters as far offshore as 100°W, west of the Galapagos Archipelago. It is estimated that nodriza operations produce as much as 80% of the total catches of the artisanal fishery. The remainder is produced by independent fibras operating in inshore waters with pelagic longlines and/or surface gillnets. A multivariate regression tree analysis was used to investigate spatio-environmental effects on the nodriza fleet (n = 6,821 trips). The catch species composition of the nodriza fleet is strongly influenced by the northwesterly circulation of the Humboldt Current along the coast of Peru and its associated cold waters masses. The target species and longline gear-type used by nodrizas change seasonally with the incursion of cool waters (< 25°C) from the south and offshore. During this season, dolphinfish (Coryphaena hippurus) dominates the catches. However, in warmer waters, the fishery changes to tuna-billfish-shark longline gear and the catch composition becomes much more diverse.

Interaction between bottlenose dolphin (Tursiops truncatus) and trammel nets in the Archipelago de La Maddalena, Italy

Interactions between bottlenose dolphins (Tursiops truncatus) and fisheries are an increasing problem in the Mediterranean and effective management measures are needed. In order to assess the impact of dolphin interactions on artisanal trammel nets, we examine 354 fishing operations performed in waters of the Archipelago de La Maddalena (Italy). We evaluate whether interactions were related to the species composition of the catch and, using the local commercial value of the target species, we assess whether there was a real economic loss for fishermen. Bayesian models and partial correspondence analysis were used to determine the extent to which dolphin interactions and habitat differences contributed to variation in the species composition of catches. CPUE for fishing operations with no dolphin interactions was significantly higher than that for operations with dolphin interactions, although clearly this does not confirm a direct causal link, and associated economic loss was estimated to be non-significant. Geographic location, season, depth of seabed, moon phase, and mesh size were all important factors affecting the amount and species composition of the catch. Our results suggest that it is likely that these differences in species composition are due to a mixture of habitat and dolphin-induced effects.

Characterizing the fishing strategies and the temporal dynamics of the small-scale fleet operating in the Cíes Islands (NW Spain)

Characterizing the fishing strategies and the temporal dynamics of the small-scale fleet operating in the Cíes Islands (NW Spain)

한국 근해 쌍끌이대형저인망어업의 어장 변화

Changes in fishing ground of the large pair trawler were investigated by year, month and species off Korean waters. We used catch data by sea-block lat.<TEX>${\times}$</TEX>long.:<TEX>$30^{\prime}{\times}30$</TEX>) of the National Fisheries Research and Development Institute (NFRDI) and monthly fishing production statistics of Korean statistic information service from 1990 to 2007. In the 1990s, the demersal fish like Larimichthys polyactis, Collichthys sp, Portunus trituberculatus and Muraenesox cinereus were the dominant species, and in the 2000s, they were changed from demersal fish into pelagic fish like Scomberomorus niphonius, Scomber japonicus, Engraulis japonicus and Todarodes pacificus. Species composition of catch showed temporal variation by cluster analysis deviding into 4 period, 1990-1994, 1995-2000, 2001-2003 and 2004-2007. Fishing ground in the 2000s was decreased up to 2/3 in the 1990s, while the density of catch in the fishing ground in 2000s was higher than the 1990s.