Target Fish Species Research Articles

Assessment of Stock Status, Metal Contents with Human Health Risk of Gudusia chapra from Oxbow lake, Bangladesh

The current study is focused on a comprehensive stock assessment of Gudusia chapra to assess the stock status along with feeding habits, essential minerals content and risk to human health from exposure to heavy metals. A total of 723 specimens from the Bukvora Baor, Bangladesh were used to estimate the total body length (TL) and body weight (W) which ranged from 5.5 to 14.5 cm and 1.62–26.45 g, respectively. The estimated asymptotic length (L∞) of this species (15.38) was in comparison with average length at 10 cm from 723 specimens along with the rate of 0.70 yr−1 for approaching to asymptotic length. The obtained growth performance index (φ) 2.2 indicates that this species is not economically feasible to bring under aquaculture. At an average annual water surface temperature of 28 °C, natural mortality, 1.71yr−1 indicating good ecological suitability of Bukvora oxbow lake (Baor). The estimated current exploitation ratio (0.24) reflected under-exploitation status with total instantaneous mortality (2.25 years−1) and fishing mortality (0.55 years−1). The recruitment pattern of this species was observed across the year, with main peak occurring during the period of April to May. The estimated total steady state biomass (3.91 metric ton) and MSY (4.40 metric ton) based on length-structured virtual population analysis (VPA) length-structured virtual population analysis (VPA) through FiSAT II schedule indicating the sustainable production of this species. The obtained values of proximate compositions (% of protein, fat, Moisture, ash) showed no significant variations during different seasons throughout the year. The monthly measurements of GaSI showed significant alterations (p < 0.05). The value of essential minerals (Na and Ca) was recorded 9.18 mg and 245.19 mg per 100 g of fish flesh, respectively. Target hazard quotient and Cancer risk for all detected heavy metals were far below the recommended levels by United States Environmental Protection Agency. Therefore, the target fish species from oxbow lake is safe and have no human health risk. Therefore, the outcomes of this research would be very worthwhile in carrying out specific management for G. chapra in Baor ecosystems.

Study on feeding behavior and biological sound of Sebastes schlegelii

The construction of marine ranches can enrich and conserve the fishery resources and improve the marine ecosystem, which helps realize the sustainable utilization of these resources. Sebastes schlegelii is a major breeding and releasing fish species in the marine ranches of North China. Its behavioral characteristics can be understood better by researching its vocalization, which will provide data support for constructing acoustic taming marine ranches with S. schlegelii as the target fish species. However, there are few studies focusing on its sounds and behaviors. Therefore, based on the passive acoustic monitoring technology, the audios of underwater noises made by S. schlegelii were extracted using an AQH hydrophone. The high-definition internet protocol camera was used to monitor the behavior change of S. schlegelii. Then, by collating and replaying the collected audios and videos, the feeding behavior and biological noises of S. schlegelii were matched to analyze their relationship. Results are as follows: (1) The noise of chewing settling granular baits (Φ5.0 mm) has a main frequency band and sound pressure level of 2000~4500 Hz and 96.53 ± 0.65 dB, respectively; in this feeding process, the main frequency band and sound pressure level of the swimming noise are 25~400 Hz and 95.63 ± 0.38 dB, respectively; the values are 500~700 Hz and 97.34 ± 4.91 dB, respectively, for the noise of flapping the water with the tail. (2) The sound signals emitted by S. schlegelii are mostly presented as single pulses during normal habitation or ingestion of baits on the surface of the water tank. However, S. schlegelii will attack and fight against each other when scrambling for baits, during which these signals are presented as continuous pulses. To sum up, the vocalization of S. schlegelii is closely related to feeding activities, and the sounds produced under different behaviors have specific biological significance.

Comparing environmental DNA with whole pond survey to estimate the total biomass of fish species in ponds

Abstract Environmental DNA (eDNA) has recently been developed for detecting the distribution of macroorganisms in aquatic systems and for estimating biomass/abundance. Although positive relationships between eDNA concentrations of species and biomass/abundance have been observed in previous studies, estimation of total biomass in a particular ecosystem based on eDNA concentration has not been investigated. To test this, we sampled eDNA from the littoral and pelagic zones of eight small ponds in Japan. Then, we drained ponds to capture all fish inhabiting each pond. We compared the eDNA copies measured by quantitative real‐time polymerase chain reaction analysis with the captured biomass of three dominant fish species (common carp, bluegill sunfish, and largemouth bass) obtained by direct capture. Differences in eDNA concentrations were compared between the littoral and pelagic zones of each pond. We found positive relationships between the eDNA copies and the whole captured biomass of all target species using Type II logarithmic equations, and the eDNA copies appeared to be saturated at a higher total biomass. We found positive correlations between the total number of eDNA copies and the total captured biomass of three fish species. This demonstrated the first step in estimating the population biomass of target fish species under natural conditions using eDNA measurement.

Potentially Toxic Elements in Water, Sediments and Fish from the Karstic River (Raša River, Croatia) Located in the Former Coal-Mining Area.

The assessment of the environmental quality of a sensitive karst aquatic system under the centuries-long anthropogenic influence of the coal mining industry is important for both improving the quality of water resources and protecting aquatic wildlife and human health. In this study, we investigated the anthropogenic impact on the aquatic environment of the upper and middle course of the Raša River through the analysis of a suite of metal(loid)s in three aquatic compartments (water, sediment, fish) using inductively coupled plasma mass spectrometry (ICP-MS). Concentrations of inorganic constituents in water were low, while the chemical composition of stream sediments mainly reflected the geological background of the area, indicating the origin of metal(loid)s from predominantly natural sources. Although comparison with PEC-Q values indicated that existing sediment quality conditions could pose a threat to benthic organisms with regard to Cr and Ni, the constant vertical profiles of these elements suggested their natural origin from the weathering of flysch. Element levels in the muscle of targeted fish species were in accordance with the values typical for low-contaminated freshwater systems, while levels of Cd, Pb and Hg were mostly below the European regulatory limits for toxic elements in foods, indicating that the low concentrations of most contaminants in muscles of fish from the Raša River do not present a risk to humans or other consumers. The obtained data indicated a generally low contamination status of the western part of the Raša River basin with regard to the analyzed inorganic elements.

Interdisciplinary design of a fish ramp using migration routes analysis

The study presents several steps of a fish ramp geometry optimization performed with a 3D numerical model DualSPHysics, which is based on the smoothed particle hydrodynamics (SPH) method. The optimization process led to the design of a bottom ramp that is capable of providing suitable conditions for the migration of target fish species (Salmo truta, Phoxinus phoxinus, Cottus gobio, and Eudontomyzon vladykovi). Migration routes were determined as complex 3D volumes of fluid according to the simulated velocity field in various steady flow conditions. Including three categories of potential migration zones (rest, effort, and limit zones), migration routes were quantified in high detail in terms of the size and position of each zone, and in terms of the distance from a given fluid part to the nearest rest zone. The interdisciplinary approach of this study also led to the development of new tools for the DualSPHysics model, specifically suited to improve functionality in eco-hydraulics research.

Habitat response of adult fish species under the influence of ecological flow and hydrodynamic regime in perennial river system

AbstractThe escalating anthropogenic activities in recent decades are constantly affecting the aquatic ecology and posing a threat to freshwater species. In this study, a two‐dimensional ecohydraulic model and multiple criteria decision analysis (MCDA) coupled framework is employed in the Dikhow River, India, to investigate the favourable habitat condition for the nearly threatened Notopterus chitala fish locally known as Chital fish. The habitat residence suitability and habitat suitability indices are calculated at the observed and ecological flows. The ecological flow rates are computed from flow duration curve shifting and flow duration curve analysis methods. The hydrodynamic computations are carried out using a 1D‐2D coupled MIKE FLOOD model. The habitat assessment of the targeted species is carried out by constructing the suitability curves from the computed hydraulic parameters at different environmental management conditions. Results from the habitat assessment curves indicate that the maximum habitat suitability index is found for the targeted fish species at average annual flow. Based on the MCDA analysis, the outer banks of the meander zones are identified as not suitable residence regions for the target species. This study revealed that the coupled approach could be useful to regulate the stream restoration strategies and identify potential habitat preference locations in the domain.

Managed culls mean extinction for a marine mammal population when combined with extreme climate impacts

Human actions led to the worldwide decline of marine mammal populations in the 18th–19th centuries. Global adoption of protective legislation during the 20th century has recently allowed many marine mammal populations to recover. This positive trend is particularly true of pinnipeds (e.g., seals and sea lions), whose recovering populations are increasingly in conflict with fisheries. Fisheries organisations have called for managed culls of sea lion populations to reduce competition for target fish species as well as damage to catch and fishing gear through operational interactions. However, despite widespread perceptions that sea lion populations are generally increasing, to-date, culls have often been considered or implemented without quantitative evidence of their impacts on seal lion population viability. This knowledge gap is particularly concerning given the expected increase in extreme climate conditions, such as extreme El Niño events, which together with culls could push sea lion populations in some parts of the world into the extinction vortex. Here, I develop stochastic matrix population models of the South American sea lion (Otaria flavescens) parameterised through a combination of species-specific field data and phylogenetic imputation using data from related species in the COMADRE animal matrix database. Using these models, I project the impact of (1) three cull scenarios with different intensity and temporal frequency targeting adult females, (2) extreme El Niño events whose frequency is modelled using a Markovian transition matrix, and (3) the interaction of culls and extreme climate events on population dynamics. I focus on the Chilean population of O. flavescens, where recent increases in sea lion numbers have triggered widespread conflict with small-scale fisheries, and where sea lion populations will increasingly be affected by extreme El Niño conditions. I find that sea lion populations decline below minimum viable population sizes within 16–28 years under all scenarios involving culls and extreme climate events. This research explicitly incorporates parameter uncertainty into population projections—in so doing, it illustrates the need for future research to collect stage-specific, annual population data to reduce uncertainty regarding marine mammal vital rates.

Modelling the hydraulic characteristics of diaphragm fishways and the effects on fish habitats

Diaphragm fishways are often used in fishway engineering construction. Although there are an increasing number of new types of fishways, other types of diaphragm fishways can be derived from the combination or evolution of the following three basic types of fishways: vertical slot, overflow weir and orifice. To compare the hydraulic characteristics of different foundation types of fishways, the operations of vertical slot fishways, overflow weir fishways and orifice fishways are calculated by numerical simulation, and we comprehensively compare the flow field characteristics and application scenarios of various types of fishways from the two dimensions of hydraulic characteristics and application characteristics. This paper analyses the hydraulic characteristics of the flow field, such as velocity distribution and turbulent kinetic energy, and analyses the application characteristics of the fishway from the aspects of applicable flow, favourite swimming speed range, explosive swimming speed, fish passing position, and the matching characteristics of typical target fish. It is concluded that the vertical slot fishway can be widely applied to different target fish species due to its own advantages, such as less impact from environmental conditions. The characteristics of the overflow weir fishway and orifice fishway need to be analysed in combination with the hydraulic characteristics of the fishway, the swimming ability of the target fish species and the natural environmental conditions.

Evaluation of Locomotion Complexity in Zebrafish after Exposure to Twenty Antibiotics by Fractal Dimension and Entropy Analysis.

Antibiotics are extensively used in aquaculture to prevent bacterial infection and the spread of diseases. Some antibiotics have a relatively longer half-life in water and may induce some adverse effects on the targeted fish species. This study analyzed the potential adverse effects of antibiotics in zebrafish at the behavioral level by a phenomic approach. We conducted three-dimensional (3D) locomotion tracking for adult zebrafish after acute exposure to twenty different antibiotics at a concentration of 100 ppb for 10 days. Their locomotor complexity was analyzed and compared by fractal dimension and permutation entropy analysis. The dimensionality reduction method was performed by combining the data gathered from behavioral endpoints alteration. Principal component and hierarchical analysis conclude that three antibiotics: amoxicillin, trimethoprim, and tylosin, displayed unique characteristics. The effects of these three antibiotics at lower concentrations (1 and 10 ppb) were observed in a follow-up study. Based on the results, these antibiotics can trigger several behavioral alterations in adult zebrafish, even in low doses. Significant changes in locomotor behavioral activity, such as total distance activity, average speed, rapid movement time, angular velocity, time in top/bottom duration, and meandering movement are highly related to neurological motor impairments, anxiety levels, and stress responses were observed. This study provides evidence based on an in vivo experiment to support the idea that the usage of some antibiotics should be carefully addressed since they can induce a significant effect of behavioral alterations in fish.

Juvenile fish stranding induced by upstream gate operation: A risk assessment through eco-hydraulic modeling

Rapidly changing flows in regulated rivers can significantly impair freshwater biotas. At present, this issue is mostly addressed by hydropeaking research. In contrast, only limited information is available concerning the environmental effects of sharp streamflow variations determined by manmade manipulation other than hydroelectricity generation.In this paper, we assessed the stranding risk of juvenile marble trout (Salmo marmoratus), an endemic species of particular interest in the study area, during rapid streamflow decrease controlled by upstream gate operation. Our investigation focused on the falling limb of a regulated flood hydrograph in a residual-flow reach of the Ticino River, located few kilometers below its outlet from Lake Maggiore (Northern Italy).The stranding risk assessment was carried out by coupling two-dimensional unsteady flow simulation and standard habitat suitability modeling. Specifically, we adopted univariate habitat suitability curves, and a threshold for the critical rate of decrease of the water surface elevation (downramping rate), commonly used in hydropeaking assessments. Our results evidenced potential stranding occurrence of the target fish species, and possible mitigation by reducing the rate of streamflow decrease before restoring the minimum flow after flood spilling. However, more reliable estimates, including partitioning the stranding risk into classes, are challenged in our opinion by difficulties arising from extensive field validation and related selection of model parameters.In a global context characterized by the urgent need of mitigating the hydro-morphological alteration of regulated rivers, we are confident that the presented approach could support an improved streamflow management in river reaches below reservoirs and regulated lakes, therefore arousing attention and research advancement by the scientific community.

Baited video, but not diver video, detects a greater contrast in the abundance of two legal-size target species between no-take and fished zones

Inherent differences between baited remote video versus diver-operated video survey methodologies may influence their ability to detect effects of fishing. Here, the ability of no-take zones (NTZs) to provide protection for legal-sized fish from targeted species within the Ningaloo Marine Park (NMP) was assessed using both baited remote underwater stereo-video (stereo-BRUV) and diver-operated stereo-video (stereo-DOV). The relative abundance of legal-sized individuals of three recreationally targeted fish species, spangled emperor Lethrinus nebulosus, chinaman cod Epinephelus rivulatus and goldspotted trevally Carangoides fulvoguttatus, were examined using both methodologies inside and outside six NTZs across the NMP. Stereo-BRUVs found positive effects of protection on the relative abundance of legal-size C. fulvoguttatus and L. nebulosus in NTZs. Stereo-DOVs, however, did not detect any differences in relative abundances and sizes of these species between areas opened and closed to fishing. These contrasting results suggest that choice of sampling methodology can influence interpretations of the ability of NTZs to provide adequate levels of protection for target species. Our results suggest that stereo-BRUVs are a superior technique to stereo-DOVs for assessing the effectiveness of no-take zones for protection of fishery target species, reflecting bait attraction and an absence of diver influence on fish behaviour.

Effects of spatial management of a penaeid fishery on other target fish species in eastern Australia

AbstractTemporal and spatial closures are often used to manage harvest by trawl fisheries. Trawl closures implemented to benefit a particular species may also benefit other species, but these indirect effects are rarely quantified. Using the New South Wales (Australia) Ocean Trawl Fishery as a case study, the potential unintended effects of trawl closures designed to protect juvenile eastern king prawn were explored for other quota managed Sillaginidae within the fishery (stout whiting Sillago robusta and eastern school whiting Sillago flindersii). Both species of whiting were more abundant within closed areas than adjacent areas, and spawning‐sized stout whiting were proportionally more abundant within closed areas. Thus, closures implemented to protect prawns also provided protection for exploited whiting species, including spawning‐sized individuals, enhancing their overall impact on the fishery. Spatial management of trawl fisheries elsewhere in the world may also similarly benefit other exploited species.

Hotspot Habitat Modeling of Skipjack Tuna (Katsuwonus pelamis) in the Indian Ocean by Using Multisatellite Remote Sensing

Skipjack tuna (SKJ) is one of the most targeted fish species globally, especially in the Indian Ocean. SKJ fishery data from Iranian purse seiners and multisatellite remote sensing data were used for hotspot habitat modeling from 2010 to 2018. Spatial and temporal variables were the most important predictors in the generalized additive model (GAM), and 58.6% of the variance was explained. In the MaxEnt model, sea surface temperature (SST), eddy kinetic energy (EKE), and sea surface height (SSH) were the most important predictors of SKJ hotspot habitat suitability in the tropical Indian Ocean between 2°S and 2°N. Furthermore, of the total studied area in the Indian Ocean defined as optimal habitat (habitat suitability index&gt;0.6), 6.8% and 5.3% exhibited ordinary habitat suitability (AUC=0.934, P&lt;0.01) and hotspot habitat suitability (AUC=0.952, P&lt;0.01), respec tively. Iranian purse seiners are distributed mainly in tropical areas, and in the present study, SKJ habitat was affected by environmental variables, as determined using multisatellite remote sensing data. In general, for effective regional monitoring and management strategies to ensure sustainable fisheries, diverse datasets compiled using satellite datasets and habitat modeling can help identify potential hotspot habitats, thereby enabling more accurate suitable habitat zone predictions and more efficient stock management.

Depth as a fish refuge from spearfishing at Rapa Nui: Flight behaviour in the Pacific rudderfish Kyphosus sandwicensis

Abstract Spearfishing, a common activity among Pacific Islanders, has been described to strongly modify the behaviour of target fish species. Rapa Nui (Easter Island), a remote Chilean oceanic island, has suffered a serious decline in its nearshore fish stocks through overfishing. In this study, the flight initiation distance (FID) of the Pacific rudderfish Kyphosus sandwicensis was measured at depths normally accessed by free divers and at deeper depths around Rapa Nui and the no‐take Motu Motiro Hiva Marine Park (MMHMP). The overall FID at MMHMP was significantly shorter compared with that recorded in shallow waters at Rapa Nui, but did not differ from the FIDs recorded in deeper waters at Rapa Nui. The biomass of K. sandwicensis did not differ among study sites, but was significantly higher at deeper depths, supporting the hypothesis of depth refuge from fishing at Rapa Nui. Based on these findings, spatial and technical management strategies are proposed to help conserve the nearshore fish populations, such as the establishment of no‐take zones and the enhancement of regulatory frameworks for coastal fisheries.

Swimming ability of fifteen target fish from eight hydropower stations in China

近几年我国水电站过鱼设施设计已将过鱼对象游泳能力作为重要参考. 以我国8个水电站主要过鱼对象为研究目标，在野外实验设施条件下测试了15种鱼(四大家鱼组、裂腹鱼组和鳅组)的感应流速和爆发游泳速度. 采用多元线性回归法分别分析了各组鱼体长及水温对游泳能力的影响，并构建了优化的游泳能力预测模型. 结果表明，四大家鱼组、裂腹鱼组和鳅组的感应流速和爆发游速皆与体长呈负相关，感应流速与水温也皆呈负相关关系. 水温升高使四大家鱼组和裂腹鱼组的爆发游速能力增强，而水温对鳅组鱼的爆发游速影响不大，可能与鳅科鱼类特殊的腹部吸附行为有关. 利用绘制的鱼感应水流和爆发未疲劳的数量百分比的生存曲线进行上行及下行过鱼设施流速设计. 结果表明：当鱼感应水流的数量百分比为90 % 时，四大家鱼、裂腹鱼和鳅组幼鱼感应流速分别为3.00、1.67和3.22 BL/s，裂腹鱼和鳅组成鱼感应流速分别为1.27和2.09 BL/s；当鱼爆发未疲劳的数量百分比为90 % 时，四大家鱼、裂腹鱼和鳅组幼鱼爆发游泳速度分别为8.13、9.27和9.61 BL/s，裂腹鱼和鳅组成鱼爆发游泳速度分别为7.64和7.77 BL/s. 当以裂腹鱼或鳅成鱼为主要过鱼对象时，上行过鱼设施内流速范围建议为1.27~7.64和2.09~7.77 BL/s. 当以四大家鱼、裂腹鱼或鳅幼鱼为主要过鱼对象时，下行过鱼设施入口流速建议小于8.13、9.27和9.61 BL/s. 本研究结果可为我国水电站主要过鱼对象的过鱼设施设计提供参考依据.;In recent years, the design of fish passage has taken the swimming capacity of target fish as an important criterion. Fifteen fish species from eight hydropower stations in China, including the four major Chinese carp, Schizothorax and Cobitidae, were selected as target species. Swimming capability was assessed by measuring induced flow velocity (U_ind) and burst swimming speed (U_burst) under identical test conditions. The relationship between U_ind (or U_burst), water temperature (T) and body length (BL) was assessed using multiple linear regression models and the optimal prediction model of swimming capability was constructed. U_ind and U_burst were negatively related to body length, while temperature effect between U_ind and U_burst varied between the three target fish species: U_ind was negatively related to temperature; U_burst was increased with the temperature for the four major Chinese carp and Schizothorax, while the temperature had little effect on U_burst of Cobitidae, which may be related to the special abdominal adsorption behavior of this fish. The percentage of fish either induced to swim (U_ind) or that were not exhausted (U_burst) was plot using survival curves, which was used to set fish passage design criteria. The result showed that 90 % of fish induced to swim were 3.00 BL/s for juvenile four major Chinese carp, 1.67 and 1.27 BL/s for juvenile and adult Schizothorax, 3.22 and 2.09 BL/s for juvenile and adult Cobitidae, respectively. The 90 % of fish were not exhausted were 8.13 BL/s for juvenile four major Chinese carp, 9.27 and 7.64 BL/s for juvenile and adult Schizothorax, 9.61 and 7.77 BL/s for juvenile and adult Cobitidae, respectively. The recommended pool velocity range of fish passage for upper migration was 1.27-7.64 BL/s for adult Schizothorax and 2.09-7.77 BL/s for adult Cobitidae, respectively. The inlet velocity of fish passage for downstream migration was recommended to be less than 8.13, 9.27 and 9.61 BL/s for juvenile four major Chinese carp, juvenile Schizothorax and juvenile Cobitidae, respectively. The results are helpful for the design of fish passage for the main target fish of hydropower stations in China.

Relationships between length-weight, length-length, and fish length to otolith morphometry in Rita rita (Hamilton, 1822)

The present study deals with fish length-weight, length-length, length-otolith size and length-otolith weight relationships in Rita rita. Specimens (N = 117) were collected monthly from September 2018 to August 2019 from Narora site of the River Ganga, India. The slope (b) in length-weight relationship equation was 2.40, suggesting a negative allometric growth pattern. The Student’s t-test showed no significant differences in the size of right and left otoliths in Rita rita, therefore, a single linear regression based on left otoliths was used. Fish length was plotted against otolith length, otolith height and otolith weight. The linear regression model was found to fit the data well for fish length to otolith size. Fish length was positively correlated with otolith height (R2 = 0.97), otolith length (R2 = 0.94) and otolith weight (R2 = 0.91). The mean value of condition factor was 1.13, which suggested a good condition of the target fish species in the River Ganga. Findings of this study could be used to study the population characteristics of Rita rita, and to explore the food and feeding biology of piscivores based on correlating the otolith morphometry of the prey items to the fish length at age.

A checklist on the status of targeted fish species in selected communities of Ondo coastal waters, Nigeria.

The increased human activities resulting from industrialization and urbanization around the Ondo section of the coastal waters of the Atlantic Ocean have significantly affected the environment. To this end, the water quality, fish abundance and target status of fish species were identified, not-withstanding the influence of human activities on the water quality and its effects on fish abundance. Four fishing communities were purposively selected based on geographical location and accessibility along the coast; Ayetoro and Idi-Ogba communities on the eastern side and Eruna-Ero and Igbokoda on the western side. A total of 120 structured questionnaires were randomly administered using snowball technique at 30 per site. Erunna-Ero community measured the highest mean temperature, dissolved oxygen, salinity and conductivity with 29.39 0.30 oC, 4.48 0.06 mg/L,10.68 0.39ppt and 40.70 0.18 S/cmrespectively, while pH was highest in Idi-Ogba community (6.47 0.00). A total of 61.67% were within 21-40 age brackets; 69.17% were males, and 75% of the males engaged in fishing activities. Agricultural activities were high (97%) with most wastes emptying into the river (85.83%). A total of 27,622 fish individuals were identified across the fishing communities with Igbokoda having the highest abundance (38.13%) and Cynoglossus browni (75.18%) was the highest fish species. In the past, three (3) economically important fish species were of major target but a reduction to two (2) species was observed at the time of study which indicated a reduction in target fish species in Igbokoda community. An increase from three (3) to four (4) target species were observed in Ayetoro, Erunna-Ero, and Idi-ogba communities which indicated an increase in target fish species. The study showed the activities around the coastal water dictated the abundance of fish species and therefore essential to monitor the water quality parameters for the sustainability of fish species in the coastal water.

Where do the billfish go? Using recreational catch data to relate local and basin scale environmental conditions to billfish occurrence in the Eastern Tropical Pacific

AbstractRecreational fisheries in the Eastern Tropical Pacific (ETP) have increased in popularity since the 1970s, contributing to the eco‐tourism industries of many Central American economies. However, pelagic gamefish face several direct and indirect threats which can affect population health and sustainability. We use daily catch logs from three recreational fishing lodges in Guatemala, Costa Rica, and Panama as records of change in blue marlin (Makaira nigricans) and sailfish (Istiophorus platypterus) sightings per unit effort (SPUE) between 2010 and 2019. Using cross‐correlational analysis, we compared billfish SPUE to the El Niño Southern Oscillation (ENSO) Index and local oceanographic conditions (sea surface temperature [SST] and chlorophyll [chl a]) to understand how billfish availability to recreational fishers is related to environmental conditions at different time lags. Blue marlin occurrence was negatively correlated with the ENSO at time lags of 9–22 months in Guatemala and Costa Rica, while sailfish occurrence was positively correlated with ENSO at time lags of 5–10 months in all three regions. Cross‐correlations with local SST were similar to ENSO patterns; however, results were unclear and nonsignificant for local chl a. By comparing recreational fisher SPUE to reported catch per unit effort (CPUE) of these two species by the international longline and purse seine fisheries, we show possible offshore movement of fish stocks during the 2016 warming event. Recreational fishing records provide an alternative way to monitor the occurrence of targeted fish species. By determining correlations of these species to environmental conditions, we begin to distinguish the effects of natural variability in the environment, from direct anthropogenic impacts.

Comparison of live shrimp bait catch efficiency in single line fishery

On the southern coast of South Korea, dark-banded rockfish, sea bass, and red seabream are caught by single-line fishing. In particular, red seabream and sea bass are caught in the Jeollanam-do region using gear with attached fishing hooks, such as long-line and single-line gear, with live shrimp as bait. The objective of this study was to compare the catch efficiency of two types of live shrimp (naturally grown Shiba shrimp [Metapenaeus joyneri] and cultured whiteleg shrimp [Litopenaeus vannamei]) used as bait. The investigation included interviews, on-board surveys, and water tank experiments. Interviews were conducted with relevant parties to determine the preference for live shrimp as bait, and the results showed a greater preference for cultured whiteleg shrimp. Further, an on-board survey was conducted to compare catch efficiency between these two types of live shrimp bait for single-line fishing. The on-board investigations were conducted once or twice a month between June and October. In total, the amounts of fish caught using naturally grown Shiba shrimp and cultured whiteleg shrimp were 56 and 52, respectively. Of these, the numbers of sea bass, the primary target fish species, caught using naturally grown Shiba shrimp and cultured whiteleg shrimp were 43 and 40, respectively. Thus, the results showed that there was almost no difference in the number of fish caught based on the bait used. However, according to a water tank experiment, cultured whiteleg shrimp survived longer than naturally grown Shiba shrimp.

Reef fish community structure in the islands of Paraja Bay, Pandeglang District, Banten, Indonesia

Abstract. Mujiyanto, Sugianti Y, Afandy YA, Rahayu R, Bidikusuma RA, Nasriri AS, Syam AR, Purnaningtyas SE. 2021. Reef fish community structure in the islands of Paraja Bay, Pandeglang District, Banten, Indonesia. Biodiversitas 22: 4402-4413. Paraja Bay waters have five small islands that coexist with Ujung Kulon National Marine Park and act as a buffer zone for the diversity of fishery resources. This study aimed to assess the reef fishes community structure at small islands in Paraja Bay. Observations were made in 20 locations during August and September 2019 in the five small islands. Reef fishes community structure showed 106 species as included major group (54 species), indicator group (24 species) and target group (28 species), among five small islands, i.e. Badul, Mangir, Oar, Sumur and Umang Islands. The highest reef fishes abundance was founded in Umang Island waters. Several target fish species recorded during the study were mature fish (such as those targeted by fishermen). Only a small proportion were juveniles. Reef fish community structure was categorized as stress community to stable community with its indication was low diversity value, high evenness index, and low dominance. The low diversity index value illustrates that the level of uniformity of reef fish species in Paraja Bay waters is high. This condition is evidenced by each coral fish group's evenness index included in the main species group around 0.93 to 0.98. The target species is 0.88 to 0.99.