Sea Fisheries Research Articles

Chamelea gallina reproductive biology and Minimum Conservation Reference Size: implications for fishery management in the Adriatic Sea

BackgroundThe striped venus clam Chamelea gallina is an economically important species in Adriatic Sea fisheries. The use of hydraulic dredging for its catch has a long history in Italy and its management faced several stages of development in the last 40 years. A great effort has been made in the past two decades to move from poorly or weakly managed fisheries to a well-structured co-management system to improve the sustainability of this fishery. However, a prerequisite for appropriate resource management is a sound knowledge of the biology and reproductive strategy of the species.ResultsWe investigated three major biological features– the gametogenic cycle, size at sexual maturity and partial fecundity – by microscopic, histological and video analysis techniques. We demonstrated that its breeding season is driven by rises in seawater temperature and chlorophyll-a concentration and that its spawning period lasted from March to September. Size at sexual maturity was reached very early in the life cycle. As regards partial fecundity – the number of mature oocytes potentially released by females with ripe gonads in a single release event – varied in relation to size. Nevertheless, the reduction on the Minimum Conservation Reference Size (MCRS) from 25 to 22 mm (Delegated Regulation (EU) 2020/2237) lead to a 40% reduction in the number of emitted eggs.ConclusionsWe suggest that the ability of Adriatic clam stocks to withstand the strong fishing pressure of the past 40 years and the present one is due to their high reproductive potential and multiple spawning events combined with the effect of management measures (closed areas/seasons, quota, MCRS) and technical constraints on the gear and the sieve on board. Moreover, since the reduced MCRS for Venus shells is still larger than the size at maturity, it will probably not be detrimental to the reproductive capacity of the stock.

Quantifying socio‐economic novelty in fisheries social‐ecological systems

AbstractSocio‐economic development has shaped fisheries social‐ecological systems (SES) worldwide across different scales. No work has yet undertaken how this development led to novel, not experienced before, systems structure in marine SES. Here, we quantify socio‐economic novelty as the degree of dissimilarity relative to a specific spatiotemporal baseline in the Baltic Sea fisheries SES between 1975 and 2015. We used catch by "gears," catch by "commercial groups" and trade ("import" and "export") as respective indicators of novelty at national, regional and international governance levels. We found that socio‐economic novelty increased over time nonlinearly in relation to the 1975–1979 baseline. The contribution to total novelty shifted from the dominance of “gears” and “commercial groups” in the late 1990s and early 2000s to “import” and “export” after the mid‐2000s, i.e. from national and regional levels to the international level. The fastest increase in novelty occurred with the trade dominance shift, primarily related to monetary value rather than quantity. Spatially, novelty emerged with a large difference across countries, and a major contribution by Sweden, Denmark and Poland. We identified the influence of different management interventions and governance actions on the emergence of novelty in the Baltic SES. The decreasing socio‐economic novelty at national and regional levels could indicate reduced variability due to management intervention in recent years which might decrease SES resilience to shocks. Calculating socio‐economic novelty and studying its drivers at different scales could provide a better understanding of SES complexity and inform urgently needed adaptation and transformation towards sustainable future pathways.

Public health impacts of an imminent Red Sea oil spill.

The possibility of a massive oil spill in the Red Sea is increasingly likely. The Safer, a deteriorating oil tanker containing 1.1 million barrels of oil, has been deserted near the coast of Yemen since 2015 and threatens environmental catastrophe to a country presently in a humanitarian crisis. Here, we model the immediate public health impacts of a simulated spill. We estimate that all of Yemen’s imported fuel through its key Red Sea ports would be disrupted and that the anticipated spill could disrupt clean-water supply equivalent to the daily use of 9.0–9.9 million people, food supply for 5.7–8.4 million people and 93–100% of Yemen’s Red Sea fisheries. We also estimate an increased risk of cardiovascular hospitalization from pollution ranging from 5.8 to 42.0% over the duration of the spill. The spill and its potentially disastrous impacts remain entirely preventable through offloading the oil. Our results stress the need for urgent action to avert this looming disaster.

Catches in abandoned snow crab (Chionoecetes opilio) pots in the Barents Sea

During a 2018 retrieval cruise for abandoned snow crab (Chionoecetes opilio) pots in the Barents Sea, approximately 8600 pots abandoned 1.5 years earlier were recovered. Forty-three percent of a subsample of 1000 pots contained snow crabs, with an average of three crabs per pot. Most of the crabs were alive (~98%) and dominated by large males. Pinch injuries and limb loss were common and tended to decline with increasing crab size. Reflex testing showed that the crabs were vital (i.e. the crabs moved their legs, chelipeds and maxillipeds when stimulated), which was supported by a relatively high meat content. However, energy reserves in the digestive glands (hepatopancreas reserves) were low, indicating overall energy deficiencies. Our results indicate considerable unaccounted mortality due to self-baiting, continued catch and cannibalism. The findings demonstrate that snow crab pots which are lost or abandoned in the Barents Sea fishery maintain huge potential for ghost-fishing impacts.

Long-term dynamics for stocks of sablefish Anoplopoma fimbria in the western Bering Sea and prospects for their fishery

Sablefish is an endemic species of the North Pacific. Its range extends from California Peninsula, along the Pacific coast of the US and Canada to Aleutian Islands and further, along the Pacific coast of Kamchatka and the Kuriles to the central part of Honshu Island. They dwell also in the Bering Sea and southeastern Okhotsk Sea. Sablefish are the most abundant in the southeastern Bering Sea and in the Gulf of Alaska, that is conditioned by favorable conditions for their larvae and juveniles. In the Asian part of the range, the environments are generally more severe, and reproduction of sablefish is rather risky. Following to the results of modern genetic studies, the sablefish stocks are distinguished by high genetic homogeneity that suggests a common population with the main spawning grounds in the southeastern Bering Sea, at the Pacific coasts of Aleutian Islands, in the Gulf of Alaska, and at the coasts of British Columbia, Washington, Oregon and California. Dynamics of the sablefish biomass is considered on the data of bottom and midwater trawl surveys conducted by TINRO in 2003–2020, fishery statistics, and accessible data of NOAA (USA). Sharp increasing of the biomass and annual catches is noted both in the eastern and western Bering Sea in the last few years because of appearance of several strong year-classes. Western Bering Sea stock depends on migration of recruits from the common spawning grounds in the southeastern Bering Sea. For the western Bering Sea, two main ways of such migration are possible: i) active migration of juveniles with benthic habitat; and ii) passive transfer of pelagic larvae and early juveniles across the Bering Sea through the system of surface currents. The latter mechanism supports the sablefish recruitment in the bays of the western Bering Sea and, to a lesser extent, at the eastern coast of Kamchatka. Sablefish in the West Bering Sea fishery zone were caught in 2010–2020 mostly as by-catch for trawling and longline fishery (93 %), other 7 % were landed by specialized longline fishery. The basic points for managing the sablefish fishery in the West Bering Sea zone are defined. About 400 t of sablefish is permissible to catch annually in the West Bering Sea fishery zone in conditions of modern high stock of this species. This value includes 100–120 t that will inevitably be caught as by-catch and the rest of 280–300 t is a foreseeable resource for organization of specialized fishery.

Standardization of landing efficiency for opilio crab in the western Bering Sea by using of generalized additive models

Generalized additive models are applied for standardization of daily landing per unit effort (LPUE) for opilio crab using the data of fishery statistics for the West Bering Sea fishery zone in 2003–2020. A set of 12 models with various combinations of predictors was examined and the best model with the smallest value of Akaike criterion was selected (information criterion Akaike 21743, explained variance 58.6 %). The selected model reflects the effect of depth, distance from the coast, daily effort and tensor product of geographic coordinates and day of the year. LPUE was standardized using the selected model by substituting median values of nominal predictors and modal values of categorical predictors. Then the crab stock was estimated using the state-space form of Deriso-Schnute delay-difference model. The estimates based on both standardized and nominal indices are compared and a significant difference between them is found: the stock is assessed as 23,040 t with nominal indices but as 17,070 t using the standardized indices.

A game theoretic perspective on the management of shared North Sea fishery resources: Pre and post Brexit

Since the introduction of the 200 nautical mile Exclusive Economic Zone (EEZ) regime, North Sea coastal states have cooperated in the management of shared stocks. Norway and the EU have jointly managed six shared stocks through the 1980 Agreement which includes the annual setting of total allowable catch quotas (TACs), quota shares and access agreements. This article first attempts to explain in a game theoretic context why cooperative management of shared North Sea fish stocks has been stable for more than 40 years. Brexit represented a shock to the cooperative agreement, and there are now three parties to the negotiations. The UK EEZ is important not only for British fishermen, but also for Norway and the EU27. The UK and the EU have agreed on a Trade and Cooperation Agreement which includes fisheries, but Norway and the UK have not yet reached a fisheries agreement. In the second part of the article we analyse the UK-EU fisheries agreement, the continuation of the 1980 Agreement, and the future fisheries relationship between the UK and Norway.

Modelling larval haddock Melanogrammus aeglefinus and cod Gadus morhua densities and mortality rates in hatchery mesocosms

The numbers and instantaneous mortality rate Z of haddock Melanogrammus aeglefinus and cod Gadus morhua larvae in a hatchery from 0 to 50 days post hatch (dph) were estimated directly and non-destructively. A small mesh plankton net was raised vertically in the water column from the tank base to the water surface and larvae were examined and counted. Using this direct sampling method Z was assessed through the larval period. A semi-log plot described the relationship of larval numbers on time. The Z of M. aeglefinus larvae from 0 to 50 dph was consistent between tanks, from 11.2 to 14.8% d−1 in seven rearing tanks sampled, with a common regression coefficient of 12.7%. The Z was lower for the period 10–50 dph, from 5.5 to 11.8% d−1 with a calculated common slope for all tanks giving a Z of 9.6%. Restricted data for G. morhua suggested lower mortality of Z of 7.8% d−1 from 0 to 50 dph with 4.2% solely for the period 10 to 50 dph. Avoidance of the net sampler by larvae was generally not recorded until >50 dph. The Z in both M. aeglefinus and G. morhua larvae was similar to Z calculated for these species in sea fisheries surveys. Advantages of the technique for estimating Z in hatchery mesocosms and examining causes and timing of larval mortality are discussed. Care in sampling larvae without removal from water, minimizing tank disturbance by sampling after tank cleaning, sampling across tank locations, and thorough disinfection of sampling nets are essential.

Integrated ecosystem impacts of climate change and eutrophication on main Baltic fishery resources

The Baltic Sea is a heavily impacted ecosystem with multiple pressures acting simultaneously. In order to quantify ecosystem impacts of integrated climate change and eutrophication pressures under constant high fishing pressure, and to support decision-making and policies in generating environmental and economic sustainable systems, the Baltic Atlantis holistic and mechanistic ecosystem model was applied. The overall aim was to run scenarios of separate and integrated impacts of climate and riverine nutrient load changes, taking into account the interactions of the full food web in the entire Baltic Sea. This was done to identify which of those two pressures will likely dominate the future of the Baltic Sea ecosystem, and to test effects of different riverine nutrient forcing sources as well as the Baltic Atlantis functions in relation to hydrographic spawning thresholds. By integrating the hydrography, the biology covering all trophic levels of the food web, and multiple pressures, i.e. eutrophication, climate change and fishery, we were able to evaluate relative impacts of 3 climate scenarios and 3 nutrient load scenarios, using two sources of nutrient forcing and predict likely trends in ecosystem effects. With focus on major fish stocks, our model, with its assumptions, indicated that nutrient loads are the main driver of the changes in the ecosystem as long as the hydrographic thresholds for spawning are not reached. If the thresholds are reached for the Baltic cod, climate change impact will become most important. Furthermore, higher nutrient loads resulted in cod decrease, and increase in sprat and herring. This effect is amplified by stronger climate change. Overall, it is of crucial importance for the future of the Baltic Sea fisheries and stocks that potential impacts are considered both separate and integrated in a dynamic ecosystem-based management approach.

The Dutch North Sea fishery in times of trouble and turmoil, 1806-1813

The Napoleonic years in Holland, 1806–1813, were a time of trouble and turmoil. The Dutch republican polity was ended when Napoleon proclaimed his younger brother Louis King of Holland in June 1806. In 1810, Holland even ceased to exist as an independent state, when it was incorporated in the French Empire. The Dutch also suffered a severe economic crisis after 1806, as a result of the Continental Blockade. Notwithstanding a series of regulations and a variety of offices charged with implementing them, the enforcement of the Blockade remained imperfect. Smuggling flourished, with Dutch North Sea fishermen, facilitated by the relatively mild stance of the British Navy, playing an important role. Police files, some recently rediscovered, demonstrate that their role was even more substantial when it came to the illegal transport of passengers and mail. Dutch North Sea fishermen, who dominated the illicit conveyance of travellers and correspondence, mainly lived near Rotterdam and the Meuse estuary. As well as goods and raw materials, they conveyed information and served as mediators in commercial networks. The proximity of these fishermen boosted the strategic advantage of local merchants and thereby contributed to the resilience of Rotterdam in this time of crisis.

Spatiotemporal distribution of Decapterus maruadsi in spring and autumn in response to environmental variation in the northern South China Sea

Understanding relationships between the spatiotemporal variability of fishery resources and marine environmental variables forms the basis of effective development and utilization of the northern South China Sea (NSCS) fishery resources. Decapterus maruadsi is one important pelagic economic fish which inhabits the coastal warm waters of the NSCS. We examine the spatiotemporal distribution and central of gravity (CoG) of D. maruadsi in the NSCS in spring and autumn from 2015 to 2017 with generalized additive models (GAMs), using fishing trawl data, and remote sensed sea surface temperature (SST), sea surface salinity (SSS), sea surface wind (SSW), chlorophyll a concentration (Chl-a), and the sea level anomaly (SLA) data. During spring D. maruadsi occurs mainly in a small area from 110.5–111 °E and 18.25–19.25 °N, at about 72 m, SST 24.4–26.8 °C, SSS 32.9–34.0 PSU, and SLA -0.04 to 0.04 m. During autumn these ranges shift to 112.25–114 °E and 20.25–21.25 °N, 62 m, 28.5–28.8 °C, and 33.4–34.1 PSU, respectively (D. maruadsi was insensitive to SLA during autumn). Accordingly, we deem the most important variables affecting the distribution of this species to be water depth and SSS in spring and SSS in autumn. CPUE of D. maruadsi was high in autumn and low in spring, with the CoG shifting from spring to autumn northwards by 0.4 °N and eastwards by 0.7 °E. This shift is likely influenced by this species’ life habits. Higher D. maruadsi CPUE in 2016 could partly be associated with La Nina and Typhoon climate anomalies. Our results provide a basis for scientific assessment and effective conservation of NSCS fishery resources.

Modern specialized fishery of sea fish in the western Bering Sea

The shelf and continental slope of the western Bering Sea, being among the most productive areas of the Far-Eastern Seas of Russia, became exploited by commercial fishery half a century ago, after introduction of 200-mile exclusive economic zones in 1977 and relocation of the Russian fishing fleet from the eastern Bering Sea to its western part. In 2010-2019, about 20 % of the total catch of sea fish in the Far-Eastern basin (excluding pacific salmons) were caught in the West Bering Sea fishery zone. Among the fishery districts of the Russian Far East, this area is currently the 1st one by annual catch of pacific cod, grenadiers, sculpins and sablefish, 2nd— by catch of walleye pollock, halibuts and skates, 3rd— by catch of rockfishes, and 4th— by catch of pacific herring and flounders. Features of specialized fishery in the West Bering Sea fishery zone in 2010-2019 are clarified. Now 48 types of the specialized fishery can be distinguished here, while 96.3 % of the average annual landing is provided by the following 8 most important types: walleye pollock midwater trawl fishery (77.8 % of mean annual catch); pacific herring midwater trawl fishery (6.1 %); pacific cod bottom longline fishery (4.7 %); walleye pollock Danish seine fishery (2.7 %); grenadiers bottom longline fishery (2.4 %), pacific cod Danish seine fishery (0.9 %); squids bottom trawl fishery (0.9 %); and pacific cod bottom trawl fishery (0.8 %). All these types of fishery are highly specialized and portion of the target objects in the catches ranges from 76 to 96 % (according to official statistics), while the by-catch accounted as 4-24 %. The is no specialized fishery on such objects as rockfishes, arrowtooth and kamchatka flounders, and sablefish in the West Bering Sea fishery zone, but they are landed as by-catch. The fishery statistics with the data sorting to specialized fishery and by-catch can be used quite effectively for the stocks assessment and determining acceptable level of their exploitation, with recommendations for fishery regulation, including evaluation the possible level of non-specialized by-catch.

Modernization of marine ports electrical power supply systems in the framework of zero-emission strategy

The article describes some approaches to the modernization of the power supply system of marine ports in the framework of zero-emission strategy. A case study of the Kaliningrad sea fishery port given as an example. The authors analyze the electrical power supply system of the enterprise and its power balance, proposing several solutions to improve energy efficiency, reliability and energy loss reduction using distributed renewable energy sources such as wind and solar generation.

Effect of intestinal bubble accumulation on antioxidant enzyme and lysozyme activities in the tissues of <italic>Pampus argenteus</italic>

In order to investigate the effect of intestinal bubble accumulation on the antioxidant capacity of silver pomfret <italic>Pampus argenteus</italic>, fifteen diseased fish were chosen as diseased group[(11.7±0.8)cm, (42.8±4.1)g] and fifteen healthy fish as control group [(12.5 ± 0.7)cm, (48.6 ± 5.6)g]. These fish were collected from Fuding research center of East China Sea Fisheries Research Institute in March 2019. Liver, kidney, muscle, and gill tissues of each group were collected and used to test their superoxide dismutase activity, catalase activity, malondiadehyde content and total antioxidant capacity, and kidney and gill tissues of each group were collected and used to test their lysozyme activity. The experimental results showed that the total antioxidant capacity of liver, gill and kidney of the diseased fish group decreased, and it decreased significantly in the liver and kidney(<italic>P</italic> <0.05), and the total antioxidant capacity in muscle was significantly higher than that in the control group (<italic>P</italic><0.05); the activity of superoxide dismutase and catalase in liver and muscle of the diseased group was significantly lower than that in the control group (<italic>P</italic><0.05); the malondiadehyde content in liver and muscle was significantly higher than that in the control group (<italic>P</italic><0.05), but the malondiadehyde content in gill and kidney were significantly lower than those in the control group (<italic>P</italic><0.05); lysozyme activity of gill was significantly higher than that in the control group (<italic>P</italic><0.05). Results show that: 1) During the intestinal bubble accumulation, the antioxidant enzyme activity of liver and muscle tissues of <italic>Pampus argenteus</italic> is impacted strongly. The antioxidant enzyme activity indicators of these two tissues can be used for the detection and pathological analysis of the disease; 2) The accumulation of bubbles in fish intestines is likely to be accompanied by bacterial infections, but still needs further verification.

Ecotrophic Effects of Fishing across the Mediterranean Sea

The status of the Mediterranean Sea fisheries was evaluated across the seven subdivisions of the General Fisheries Commission for the Mediterranean (GFCM), using ecotrophic and catch-based indicators for the period 1970–2017. All indicators confirmed that the fishery resources across the Mediterranean Sea are no longer sustainably exploited and that the structure and function of marine ecosystems has been altered as a result of overexploitation. Although declining catches were a common feature across the Mediterranean Sea, the pattern of exploitation and the state of stocks differed among the subdivisions, with the Levantine Sea and Sardinia having a better status. Although they only include the exploited biological resources of marine ecosystems, catch and ecotrophic indicators can provide insight on ecosystem status and fishing pressure. In the case of southern Mediterranean countries, catch and trophic levels are the only information available, which is extremely valuable in data-poor ecosystems.

Spawning technique of yellowfin tuna (Thunnus albacares) infloating nets cage

Tuna is a potential commodity because it contributes the largest fishery export. Tuna aquaculture is one of the steps that can be taken to maintain the stability of tuna fishery production. The aquaculture method using floating net cages is the most productive aquaculture technique. The study has performed in the Central Research of Sea Cultivation and Fisheries Extension Gondol, Bali. The purpose is to know how the technique of spawning yellow fin tuna (T. albacares) in floating net cages. The control issues and obstacles encountered during the process of raising the broodstock yellow fin tuna. Spawning of yellow fin tuna is done naturally. Broodstock female of yellow fin tuna used from catching process that is choosing broodstock candidate of tuna fish with weight 5 kg and length +25 cm. The weight ratio of yellow fin tuna between male and female is 3:1. Water quality parameters for yellow fin tuna larva among others: temperature 29-30°C; pH 8.2; and DO 6.0 ppm. Based on the calculation, the obtained hatching raate of yellow fin tuna is at 75.34% and the Survival Rate is 0%. Artificial feeds used in the maintenance of larvae are Nannochloropsis oculate and Brachionus rotundiformes.

A Study on Characteristics of Fuel Consumption of Fishing Fleet Depending on Domestic Littoral Sea Fisheries Catches-Focusing on Mackerel Fishing of Large Purse Seines-

A Study on Characteristics of Fuel Consumption of Fishing Fleet Depending on Domestic Littoral Sea Fisheries Catches-Focusing on Mackerel Fishing of Large Purse Seines-

Understanding the tragedy of the commons in the South China Sea fisheries: The prisoner's dilemma model revisited

The South China Sea (SCS) fisheries crisis is becoming a textbook example of the tragedy of the commons (TOC).The discussion of the SCS fisheries governance, however, has been poorly informed by the rich findings of the studies on the commons. The Prisoner’s Dilemma (PD) game model is most widely applied to examining collective action problems, including the social dilemma faced by fishers in the SCS. While generations of studies have shed light on how cooperation in the PD model could be improved, two important factors are overlooked, namely, the real motivation of the fishers and the boundary issue when the model is applied to a large scale fishery commons. Taking these two factors into consideration, the “exit” and “move” options need to be granted to the players in the PD model. In this paper, I show that incorporating the ‘exit’ and ‘move’ options into the PD model can generate new insights on how to improve fishery governance and avert the TOC in the SCS. The findings offered in this paper can help avert fishing crises in other regions, as well as other commons challenges.

EVALUATING THE USE OF THE MULTILOCUS GENETIC MARKER “5S RDNA” FOR THE DISCRIMINATION OF DIFFERENT SPECIES OF FAMILY LETHRINIDAE IN RED SEA, EGYPT

Family Lethrinidae (Sho´our fishes, Shaari fishes) is one of the key families in the Red Sea and Indian Ocean fisheries. Some of its species were recorded in the International Union for Conservation of Nature (IUCN) Red List of species as endangered. In order to develop simple genetic marker that aid their rapid identification, fin clips of four lethrinid species were collected from local fish markets in Hurghada city. These species were Lethrinus lentjan, L. harak, L. microdon, and L. mahsena. DNA was extracted from these samples and subjected to polymerase chain reaction (PCR) amplification for the mitochondrial 12S ribosomal RNA (rRNA) and the nuclear 5S rRNA genes. The 12S rRNA PCR amplicons were sequenced. GenBank comparison and phylogenetic analysis for the 12S rRNA gene sequences resulted in clear identification for the sampled species. Meanwhile, a simple, 2% agarose gel electrophoresis for the 5S rDNA ran in a low voltage for 2 hours resulted in variable intraspecific patterns. These patterns appeared as 3 PCR bands of approximately 500 base pair (bp) in length for L. lentjan; 2 PCR bands at 500 and 400 bp for L. harak; single PCR band at 500 bp for L. microdon; and 3 bands at about 750, 500, and 400 bp for L. mahsena. Band separation was clear enough. 5S rDNA exhibited an accurate, interspecific, and easy-to-use genetic marker for identification of different lethrinid species covered by the current study.

EVALUATING THE USE OF THE MULTILOCUS GENETIC MARKER “5S RDNA” FOR THE DISCRIMINATION OF DIFFERENT SPECIES OF FAMILY LETHRINIDAE IN RED SEA, EGYPT

Family Lethrinidae (Sho´our fishes, Shaari fishes) is one of the key families in the Red Sea and Indian Ocean fisheries. Some of its species were recorded in the International Union for Conservation of Nature (IUCN) Red List of species as endangered. In order to develop simple genetic marker that aid their rapid identification, fin clips of four lethrinid species were collected from local fish markets in Hurghada city. These species were Lethrinus lentjan, L. harak, L. microdon, and L. mahsena. DNA was extracted from these samples and subjected to polymerase chain reaction (PCR) amplification for the mitochondrial 12S ribosomal RNA (rRNA) and the nuclear 5S rRNA genes. The 12S rRNA PCR amplicons were sequenced. GenBank comparison and phylogenetic analysis for the 12S rRNA gene sequences resulted in clear identification for the sampled species. Meanwhile, a simple, 2% agarose gel electrophoresis for the 5S rDNA ran in a low voltage for 2 hours resulted in variable intraspecific patterns. These patterns appeared as 3 PCR bands of approximately 500 base pair (bp) in length for L. lentjan; 2 PCR bands at 500 and 400 bp for L. harak; single PCR band at 500 bp for L. microdon; and 3 bands at about 750, 500, and 400 bp for L. mahsena. Band separation was clear enough. 5S rDNA exhibited an accurate, interspecific, and easy-to-use genetic marker for identification of different lethrinid species covered by the current study.