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Simple Summary: A comprehensive assessment of the life history parameters of the invasive Atlantic blue crab Callinectes sapidus in the Lesina Lagoon (Adriatic Sea, SE Italy) in terms of abundance, sex ratio, size–frequency distribution, morphological maturation, growth, and mortality was provided adopting a suite of analytical techniques. The results of the present study can provide a valuable knowledge basis for future comparative investigations on the fishery biology of C. sapidus in Mediterranean waters. The fishery biology of the invasive Atlantic blue crab Callinectes sapidus in the Mediterranean Sea outside the eastern sectors of the basin has been only recently investigated. Here we studied the population of C. sapidus in the Lesina Lagoon (Adriatic Sea, SE Italy). In total, 838 crabs were captured monthly between February 2021 and January 2022 using fyke nets. Abundances varied seasonally with catches per unit effort ranging between 0 and 1.76 crabs fyke nets−1 d−1 in winter and summer. Spatial abundances estimated in summer by a Carle–Strub procedure ranged between 0.06 and 0.64 crabs m−2. The sex ratio (♂/♀) was close to 1:1; males prevailed only in August and September; ovigerous females occurred from April to August. The males' size at morphological maturity was smaller than females (110.6–112.3 mm vs. 122.1–123.1 mm). Seasonal von Bertalanffy growth parameters indicated that, compared with males, females showed a shorter maximum lifespan (5 vs. 8 years), a higher growth coefficient K (0.6 vs. 0.4 y−1) and growth performance index Ф' (4.6 vs. 4.3), while maximum sizes CW∞ (237.8 vs. 232.6 mm) and seasonality indices C (0.62 vs. 0.57) were similar. Furthermore, females showed higher natural and fishing mortalities and exploitation rate. We discussed the results of the present study in the context of the available literature to provide a valuable basis for the implementation of standardized Mediterranean-scale management plans, matching exploitation of C. sapidus with sustainable conservation of coastal ecosystems. [ABSTRACT FROM AUTHOR]

This study investigated artisanal fishing activity near sea cages in Güllük Bay in the southeastern Aegean Sea based on dockside sampling with local fishermen. The daily fishing activity of bogue Boops boops gillnetters was randomly observed in the ports of Göltürkbükü, Gündoğan, Yalıkavak and Torba over two fishing seasons, from November to April 2018 and 2019. A total of 18,163 kg of fish were caught in 147 daily operations. The composition of catches from the bogue gillnet fishery comprised 48 species from 30 families, including both fish and invertebrates. B. boops was the most abundant species with 91.9% of the catch, followed by Diplodus annularis, Scomber colias, Trachurus trachurus, Pagellus acarne and Scomber scombrus. The ratio of total bycatch biomass to commercial target species was 1:0.09. The fork length (FL) and weight of the 536 sampled B. boops ranged between 25.5 ± 0.12 cm and 293.6 ± 3.87 g, respectively. The highest catch per unit effort (CPUE) of B. boops occurred in April and averaged 58.83 ± 11.47 kg/1000 m, likely due to an increased catch during its spawning migration to open sea areas in spring. [ABSTRACT FROM AUTHOR]

A demersal stock assessment was conducted in Leyte Gulf from 24 April to 08 May 2020, within the 19 established fishing stations, using a bottom otter trawl with a 71 m length and a 43 m head rope. This study focused on determining the total catch, catch composition, catch per unit effort (CPUE), and biomass. A total catch of 4.22 t comprised of 230 fish species and invertebrates which belongs to 74 families was recorded in the survey. The majority of the catch belongs to family Leiognathidae, comprising 39.45%, followed by Lutjanidae, and Gerreidae, with 8.05% and 7.07%, respectively. Top species were Orangefin ponyfish Photopectoralis bindus with a composition of 25.49%, followed by Toothpony Gazza minuta (both are locally known as "sap-sap"), and Longfin mojarra Pentaprion longimanus "hubad" with 7.42%, and 5.80%, respectively. Mean CPUE and biomass were approximately 222.08 kg hr-1 and 2.81 t km-2, respectively. A 68.26% increase in biomass compared to previously conducted study in 2014 of M/V DA-BFAR was recorded. The shifting of catch composition from economically valuable to low-valued, non-targeted, and small-sized species was observed. A continuous resource assessment activity is essential to determine the changes in fishing patterns, catch rates, and catch composition, which will serve as a basis for policy formulation and future management plans and measures. [ABSTRACT FROM AUTHOR]

Objective: Recreational fishing is a growing concern in the management of fishery resources given its economic impact, the number of people involved, and the magnitude of catches. Despite its significant impact on marine resources and ecosystems, recreational fishing has received less attention in research than commercial fishing. Methods: This study focuses on marine recreational fishing in Balagne (Corsica, France, northwestern Mediterranean). It presents, for the first time in this region, valuable data on the population size of recreational fishers; their sociological profiles; fishing habits; and, specifically, catch data related to boat fishing. Result: Through an extensive telephone survey involving 387 households, we estimated that recreational fishers constitutes 10.2% of the population, with the majority being men (84.84%). The average age varies significantly based on the type of fishing practiced: 38.4 years for spearfishing, 50.2 years for shore fishing, and 56.4 years for boat fishing. Additionally, the study found that shore fishers declare practicing no‐kill fishing more frequently than do boat fishers (90.00% and 56.67%, respectively). Photographic protocol, fishing logbooks, and boarding provided data on catch composition and fishing characteristics. In the case of boat fishers, catches per unit of effort, estimated from boarding data, were found to be 1.03 ± 1.51 individuals/h/fisher and 222.32 ± 318.94 g/h/fisher. Despite the great diversity among the species caught (49 species), Comber Serranus cabrilla, Blackspot Seabream Pagellus bogaraveo, Black Seabream Spondyliosoma cantharus, and Painted Comber Serranus scriba are overly represented in number among the species of marine fish caught by boat fishers and Common Dentex Dentex dentex, Greater Amberjack Seriola dumerili, Dolphinfish Coryphaena hippurus, and Bluefin Tuna Thunnus thynnus are overly represented in weight. Among all individuals caught and measured, about one out of two individuals (48.97% of catches) does not reach the legal size. Conclusion: This study reveals the need to establish monitoring, surveillance, and control programs to ensure the sustainability of fish stocks and fisheries, including recreational fisheries. Impact statementRecreational fishing is a growing concern in the management of fishery resources given its economic impact, the number of people involved, and the magnitude of catches. This study on recreational fishing in Balagne (Corsica, France, northwestern Mediterranean) collected, for the first time in this region, data on the number of recreational fishers, their sociological profiles, and their fishing habits and specific catch data concerning boat fishers. This study shows that it is key to consider the socioeconomic and biological implications of marine recreational fishing in fish stock assessment and overall management strategies of Mediterranean coastal areas. [ABSTRACT FROM AUTHOR]

Shrimp trawl fishery is of significant importance in Saudi Arabia's marine capture fishery sector. Al Qunfudhah and Jizan are the only ports along the southern Saudi Arabian coast of the Red Sea dedicated to shrimp fishing. This study evaluates the catch per unit effort (CPUE) of targeted shrimp species along with the associated retained bycatch and discard ratios across these two trawling locations. Using daily catch data from commercial shrimp trawlers specific to each port's vessel type, this research provides the first comprehensive analysis of CPUE dynamics and fishing practices in these fishing grounds. The CPUE of target shrimps exhibited a wide range (0.01 kg h−1 to 13.08 kg h−1) with an overall mean of 1.37 ± 0.143 kg h−1. Penaeus semisulcatus emerged as the predominant species (mean CPUE: 3.77 ± 0.28 kg h−1), followed by Metapenaeus monoceros (mean CPUE: 0.1 ± 0.02 kg h−1). Significant differences in CPUE were observed among species, including P. semisulcatus, Penaeus hathor, and Penaeus pulchricaudatus, although CPUE differences between the two fishing grounds were minor, likely due to their proximity and similar environmental conditions. The bycatch analysis identified a total of 72 species across 28 families, with significant variation in the relative ratios. Sepiidae species constituted 31.8% of the total bycatch, followed by Portunidae species (24.8%). Discard patterns also varied, with Gerres oyena being the most commonly discarded species (mean discard ratio: 11.37% ± 1.89%), followed by Equulites klunzingeri (mean discard ratio: 8.76% ± 2.00%). While CPUE differences between Al Qunfudhah and Jizan were modest, this study highlights the need for expanded spatial and temporal coverage to enhance future analyses. These findings underscore the importance of integrated data for a comprehensive understanding of fishing effort and bycatch dynamics, supporting sustainable fisheries management in the Red Sea. By addressing bycatch and discard practices, this research contributes to efforts to mitigate ecological impacts and promote sustainable resource use in Saudi Arabia's fisheries sector. [ABSTRACT FROM AUTHOR]

ABSTRACT Aquatic protected areas and co‐management have been proposed as strategies for conserving fisheries resources in several world regions. We analyzed the effects of different levels of governance on yield of experimental fisheries in Amazonian floodplain lakes. Sampling between 2018 and 2022 used gill nets deployed for 24 h during flooding and receding water phases. Generalized linear models (GLMs) were fitted to catch per unit effort (CPUE) and covariates, river level, time, sampling sites, level of management of the collection sites, and lake fishery management type. CPUE was significantly related to governance, management type, sampling site, and water level. Our results indicated that areas of sustainable use where community‐based co‐management was implemented were more effective for promoting high fishery yield. [ABSTRACT FROM AUTHOR]

The abundance of fishery resources significantly impacts the ratio of fishing effort to harvest. However, traditional statistics of fishery catches or commonly used catch per unit effort (CPUE) metrics cannot accurately capture the complexity of resource abundance in the ocean. To address this issue, we propose here a novel approach that integrates the actual fishery catch from vessel logs with fishing duration obtained through automatic identification system (AIS) positioning. This combined analysis eliminates confounding factors and introduces a novel metric called "catch efficiency (CE)" to evaluate fishing operations more accurately, thereby reflecting resource abundance in a more reasonable way. In this study, we focus on the CE of squid in the Oyashio Extension region in the Northwestern Pacific. Our analysis reveals significant temporal and spatial variations of CE, manifesting in both intensity and distribution patterns. Moreover, our findings establish a close relationship between CE and background water mass distribution, chlorophyll‐a concentration, and micronekton biomass. This implies that the resource abundance of squid can be inferred by considering the varying environmental factors within the fishing area. [ABSTRACT FROM AUTHOR]

Ecosystems worldwide are increasingly being invaded by multiple species, and the rate of biological invasion is accelerating, leading to more interactions among invasive species. One such interaction that has received little attention is the phenomenon of 'serial replacement' or 'over-invasion', where an established invasive species is supplanted by a second invasive species. Understanding this interaction is important as controlling the second species could inadvertently lead to an increase in the abundance of the first species. We used a hierarchical state-space model to analyse changes in annual abundances (commercial catch-per-unit-effort) of three invasive fish species, tench (Tinca tinca), common carp (Cyprinus carpio) and redfin perch (Perca fluviatilis), in the Murray-Darling River system (MDRS), Australia between 1954–2002. Tench were present at low abundances until the mid-1970 s, before declining to the point of no commercial catch post-1989. This rapid decline coincided with a significant increase in carp abundance, suggesting that carp may have driven the tench decline through habitat modification (particularly the destruction of aquatic plants), consistent with findings from European studies that show the disappearance of tench from ponds with intensive carp farming. Redfin perch populations, were inferred to be much less impacted by the invading carp population. While carp were present in the MDRS for the duration of the study, the rapid increase in carp abundance in the early 1970 s coincided with the introduction of a specific genetic lineage—the "Boolarra strain". Our analysis provides compelling evidence of serial replacement of long-established tench by invading common carp triggered by the introduction of a novel carp strain. [ABSTRACT FROM AUTHOR]

Abstract This research paper investigates the oceanic fishery resources of the Andaman archipelago. The primary objective of this study is to gain a comprehensive understanding of the fishery and its dynamics including the environmental linkage surrounding these oceanic resources and to develop an effective strategy for sustainable exploration. Data were collected during an exploratory tuna long-line survey conducted between July 2022 and February 2023. The study documented a total of 13 species of fishes belonging to 11 genera, with tuna being the most abundant. Additionally, the study observed a significant increase in the population of pelagic stingrays, which nearly matched the number of hooked sharks (32). However, the hooking rates of sharks and bill fishes were observed to be gradually declining, resulting in a lower contribution to the overall species composition. One notable finding of the study was that site 11oN; 93oE (S4) exhibited the highest species diversity and potential. Furthermore, the aggregate hooking rates of fishes were particularly high between latitudes 11oN and 12oN. The study also analysed the seasonal distribution of each fish species and explored the correlation between environmental factors such as depth and temperature with species abundance and distribution. Statistical analysis indicates that there is no significant variation (p value = 0.20) between the environmental factors and the frequency of the species occurrence. Specifically, depth shows the highest correlation (r = 0.57) with the species distribution. In light of the diminishing hooking rate of oceanic fishery resources, the study puts forth several possible reasons and emphasizes the urgent need to implement conservation measures.

ABSTRACT Regional factors correlated with recruitment of black bass (largemouth bass; Micropterus nigricans and smallmouth bass; Micropterus dolomieu), two important fishes, are rarely studied, despite the importance of recruitment variation in influencing fish populations. We sought to identify factors that drove variation in age‐0 and age‐1 black bass abundance. Age‐0 or age‐1 black bass catch per unit effort (CPUE) in reservoirs in Kansas and Illinois, USA, was positively correlated with local short‐term (i.e., mean April precipitation) environmental variables. In contrast, age‐0 or age‐1 black bass CPUE was generally negatively correlated with long‐term environmental variables and river regulation metrics (i.e., reservoir elevation) in the Mississippi and Missouri river reservoirs. Our findings highlight that consideration of spatiotemporal scale is important when managing black bass populations. [ABSTRACT FROM AUTHOR]

Boreal lakes experience pronounced seasonal variation in abiotic factors, especially light, temperature, and oxygen. A deep boreal humic lake was sampled year‐round to test putative changes in total fish catch, species composition, catch‐per‐unit‐effort (CPUE), habitat use, fish size, and condition. Monthly sampling was conducted in Lake Pääjärvi, southern Finland, during one full year in 2020–2021 as well as in March and August 2021 and 2022. The fish community was dominated by cyprinid species in all months, but the percentage of percid fish caught increased during the warm summer period. Most fish were caught in littoral habitats and the highest catches occurred in summer, but some species (e.g., ruffe, Gymnocephalus cernua, and pikeperch, Sander lucioperca) remained abundant in the winter catch. The body size of fish was larger in the winter catch, while condition factor was higher in summer for most species. Fish species proportions in total catch, CPUE, and average size of fish were closest to the annual mean values in September, which may be used as the optimal period to monitor fish communities of similar deep boreal lakes. Our findings highlight the need for year‐round research to reveal the impacts of rising temperatures and diminishing ice‐covered periods in fish communities and lake food webs. [ABSTRACT FROM AUTHOR]

The purpose of the study is to investigate the catch composition, the amount of by- catch, the length frequency and the catch per unit of effort of bottom gillnets for catching the Tigertooth croaker, using mesh size of 73, 85 and 90 mm in the waters of the Oman Sea in the period of winter 2018 to the late spring of 2019. 973 pieces of fish including 15 families were caught, and the highest catch rate was 63.62% for the Tigertooth croaker. The rate of by- catch was 8.74%. The amount of CPUE for the mentioned mesh size was estimated as 552.9, 808.9 and 456.9 grams per net day respectively. By examining the length frequency distribution in all the meshes, it was determined that the highest frequency is in the length of 32-36 cm with 43.67%. Also, an average length of 31.80±6.64 cm was recorded in the whole operation. According to the first maturity length of the Tigertooth croaker, it was determined that the bottom gillnets available in the Chabahar region fishing grounds had a catch below the standard size, and it seems the mesh size of the net should be reviewed and standardized. [ABSTRACT FROM AUTHOR]

A new fishing technique has been introduced in Lake Kivu, across the Congo side. It consists of gillnets on which light‐emitting diode (LED) lamps are attached. Traditional fishermen have introduced the fishing technique without any studies related to the positive and drawback effects of this fishing technique. We sought to understand whether the gillnets with LED lamps fishing technique improve fishing catches and can be regarded as sustainable for the Lake Kivu ecosystem, or is it just only a marketing strategy for gillnets and LED lamp sellers. Two complementary approaches have been used in this study. Experimental fishing campaigns were conducted from June 2021 to June 2022 and monitoring of fishing team in the field coupled with surveys of fishermen about the effectiveness use of this new fishing technique. We observed that (i) 88% of fishermen using gillnet in the Bukavu sub‐basin have already adopted the recently introduced fishing technique; (ii) the average catch per unit effort of gillnets with LED lamps is higher than those without LED lamps (3.84 ± 1.95 kg/net vs. 2.69 ± 2.04 kg/net); (iii) these gillnets retrieve larger specimens (79.88 mm vs. 76.69 mm) and generate monthly a higher average profit to fishermen ($916.35) than the fishing technique lacking the LED ($807). However, (iv) the gillnets with LED lamps generates a lot of plastic trash: around 2130 kg of plastic bags/month under fishing conditions in the Bukavu sub‐basin. So, this new fishing technique is a real panacea for its practitioners, but a veritable Pandora's box generating plastic pollutants in Lake Kivu. Instead of banning this new fishing technique, we need to adapt it by using submersible LED lamps. [ABSTRACT FROM AUTHOR]

Albino-Martínez, O. and Rosales-Casián, J.A., 2024. Ecology of economically important fish at a temperate Pacific Island of Baja California, Mexico. Journal of Coastal Research, 40(5), 919–928. Charlotte (North Carolina), ISSN 0749-0208. Economically important fish were caught in rocky reefs around Isla San Martin, Baja California, Mexico to determine the composition and spatio-temporal variations, their possible relationship with temperature, upwelling and depth, and the size structure of the most abundant species. Five seasonal surveys were carried out using traps and hook-and-line at four different sites from June 2021 to May 2022. A total of 595 fish individuals (417 kg) were caught, comprising of 23 species from 10 families, and the Sebastidae family contributed the largest number of 12 species. The most abundant fish species were Caulolatilus princeps, Paralabrax clathratus, Semicossyphus pulcher, Paralabrax nebulifer, Sebastes auriculatus, S. umbrosus, and S. rastrelliger that contributed 90.2% of the total abundance. C. princeps contributed 60.8% of the abundance and 60.2% of the biomass. The first three fish species were the most important in terms of relative abundance and frequency of occurrence. The catch means (abundance and biomass) per trap or angler did not change over time; however, between sites, the average fish catch per trap (abundance and biomass) was significantly different, which presented a positive and significant relationship with depth, only. The fish richness (number of species) varied between nine (fall 2021) and 14 species in spring 2021 and 2022. The highest diversity of fish species (H' = 1.9) occurred in summer (C. princeps 41.1% abundance), and the lowest diversity (H' = 1.0) during fall (C. princeps 74.1%. abundance). Among fishing sites, the greatest diversity occurred close to Isla San Martín (El Bufeo, H' = 2.1), and the lowest diversity in the deeper sites far from the island (Bajo 6, H' = 1.0). Caulolatilus princeps presented 100% frequency of occurrence, while Chromis punctipinnis, Halichoeres semicinctus, Medialuna californiensis, and Sebastes serranoides occurred with the lowest value (4.5% each). [ABSTRACT FROM AUTHOR]

Fyke nets are the preferred type of equipment used for platypus (Ornithorhynchus anatinus) live-trapping surveys in shallow watercourses. However, numerous factors other than abundance may affect the frequency of platypus captures, including when, where and how nets are set, stream discharge and entry into nets by rakali (Hydromys chrysogaster), which create exit holes that are then also available to a platypus. A threefold difference in the mean monthly frequency of platypus captures in fyke nets is also evident across the year. To limit net evasion, it makes sense to reduce net visibility and minimise opportunities for animals to squeeze under, climb over or walk around nets. Time-lapse cameras can also be deployed at fyke-netting sites to estimate how many individuals evade capture. To protect platypus welfare and the welfare of non-target species held in fyke nets, it is important to ensure that captured animals have access to air, to check nets frequently throughout the time they are set and to release bycatch when first encountered. Fyke-netting studies typically generate sparse platypus population data, so care is needed when selecting and interpreting platypus abundance metrics generated through mark–recapture modelling or use of indices. Fyke nets are commonly used for platypus survey or other research purposes in shallow water bodies. We discuss the wide range of factors influencing the frequency of platypus captures, identify issues affecting animal welfare in fyke nets and consider the options available for estimating platypus abundance from fyke-netting data. Photograph by G. Williams/APC. This article belongs to the collection: Recent research on the platypus. [ABSTRACT FROM AUTHOR]

Jůza T, Blabolil P, Čech M, Draštík V, Kubečka J, Muškaa M, Prchalováa M, Sajdlováa Z, Tušera M, Vašeka M, Vejříka L, Peterkaa J. 2024. Fish predation on newly stocked juvenile predatory fish in a biomanipulated reservoir. Lake Reserv Manag. 40:325–337. Juveniles of pikeperch, asp, and northern pike were stocked into the Římov Reservoir. Subsequently, potential fish predators were monitored by gillnets at the stocking sites and their diet was analyzed for presence of stocked fish. Asp and European perch were predominant predators, while pikeperch and northern pike were less abundant in gillnet catches. Digestive tract analysis revealed the highest percentage of ingested fish in northern pike, followed by pikeperch, asp, and European perch. The amount of stocked fish did not correlate with the number of predatory fish caught in gillnets. When asp was stocked, this species was strongly preferred by northern pike and partly by pikeperch and 0.3 individual of stocked asp was eaten per 1 kg of predatory fish captured by gillnets. During the northern pike stocking, this species was mainly preyed upon by asp and occasionally by northern pike, and 0.8 individual of stocked northern pike was eaten per 1 kg of predatory fish. When pikeperch was stocked, it was strongly preferred by pikeperch, northern pike, and European perch, it was almost absent in the diet of asp, and 1.1 individual of stocked pikeperch was eaten per 1 kg of predators. Our results indicate that pikeperch juveniles had the highest mortality rate due to predation after stocking, mainly due to sedentary behavior and the high proportion of cannibalism. In northern pike, cannibalism was found in only one case, and was never found in asp, which was under the lowest predation pressure. [ABSTRACT FROM AUTHOR]

This research paper investigates the oceanic fishery resources of the Andaman archipelago. The primary objective of this study is to gain a comprehensive understanding of the fishery and its dynamics including the environmental linkage surrounding these oceanic resources and to develop an effective strategy for sustainable exploration. Data were collected during an exploratory tuna long-line survey conducted between July 2022 and February 2023. The study documented a total of 13 species of fishes belonging to 11 genera, with tuna being the most abundant. Additionally, the study observed a significant increase in the population of pelagic stingrays, which nearly matched the number of hooked sharks (32). However, the hooking rates of sharks and bill fishes were observed to be gradually declining, resulting in a lower contribution to the overall species composition. One notable finding of the study was that site 11oN; 93oE (S4) exhibited the highest species diversity and potential. Furthermore, the aggregate hooking rates of fishes were particularly high between latitudes 11oN and 12oN. The study also analysed the seasonal distribution of each fish species and explored the correlation between environmental factors such as depth and temperature with species abundance and distribution. Statistical analysis indicates that there is no significant variation (p value = 0.20) between the environmental factors and the frequency of the species occurrence. Specifically, depth shows the highest correlation (r = 0.57) with the species distribution. In light of the diminishing hooking rate of oceanic fishery resources, the study puts forth several possible reasons and emphasizes the urgent need to implement conservation measures. [ABSTRACT FROM AUTHOR]

Abundance of adult walleye (Sander vitreus) and sauger (Sander canadensis), two important sport fishes, decreased significantly during 2001–2022 in Lewis and Clark Lake, a border water between Nebraska and South Dakota, despite walleye fingerling stocking and stable age‐0 abundance of both species. We sought to identify factors that drove variation in age‐0 abundance from 2001 to 2022 using an information theoretic approach. Age‐0 walleye catch per unit effort (CPUE) was correlated to mean monthly outflow, mean annual precipitation, and mean April gauge height in a delta. Age‐0 sauger CPUE was correlated to adult conspecific CPUE, mean April Heating Degree Days, and mean annual precipitation. Our findings suggest that both biotic and abiotic factors were important for explaining variation in age‐0 CPUE of sauger, but mainly abiotic factors for walleye. As such, manipulation of abiotic factors (i.e., outflow) by installing entrainment barriers may be more effective than manipulation of biotic factors (i.e., stocking). [ABSTRACT FROM AUTHOR]

The composition of the fish population of the Mekong River is one of the richest on the planet, however, despite the high diversity (~1200 species) and productivity, the basis of fishing in the Mekong Delta is made up of several dozen species, the most valuable of which are members of the families Pangasiidae, Polynemidae and Sciaenidae. Information on the distribution of these taxa is fragmentary, and the role of various parts of the delta in their reproduction has not been studied. Distribution of families Pangasiidae, Polynemidae and Sciaenidae in the Mekong Delta was assessed in the dry season by midwater trawl catches in 2019 (April, December), 2021 (January, April) and 2022 (March–May). A total of 237 trawls were carried out, in the catch of which 45.9 thousand fish belonging to 36 families were found. Representatives of each of the families Pangasiidae, Polynemidae, and Sciaenidae were noted in 42–57% of all catches within the studied part of the Mekong Delta, however, the frequency of their occurrence in its various parts varies significantly. According to the Mekong Delta zonation scheme, based on the analysis of the taxonomic composition of the fish population, representatives of Pangasiidae are confined to areas of the upper and middle reaches, Polynemidae—to areas of the middle and lower reaches, while significant differences in the horizontal distribution of Sciaenidae in different parts of the delta have not been identified. Significant differences in the vertical distribution of all studied taxa were also not found. The maximum concentrations of juveniles of Pangasiidae and Polynemidae were found in the middle reaches of the delta, and Sciaenidae in the lower reaches, which indicates the important role of the respective areas in the reproduction of representatives of the studied taxa. [ABSTRACT FROM AUTHOR]

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This study analyzed the catch of the ponyfish (Leiognathus equulus) landed at Muara Kintap Fishing Port in South Kalimantan, Indonesia. Local fishermen used various gear types especially bottom trawls, beach seines, drift gillnets, and encircling gillnets within Indonesia's Fisheries Management Area (FMA) 712. While bottom trawls displayed the highest efficiency, peaking at 65,956kg, representing 98.26% of the annual total catch. Moreover, they also indicated potential overfishing, particularly in 2022. The ponyfish catches were dominated by individuals measuring between 130- 134mm and weighing 35- 39g. Length-weight relationship data revealed an isometric growth pattern (b = 2.98) for the ponyfish, suggesting good overall health (K = 1.68± 0.17). However, CPUE (Catch per Unit Effort) data from 2022 raised concerns. The peak CPUE of 89.13kg/ trip, alongside a substantial total catch of 67,122kg across 753.1 trips, significantly surpassed the catch-maximum sustainable yield (CMSY) of 28,748kg/ trip and the optimal effort (Fopt) of 882 trips/year. This suggests overfishing and a potential decline in the ponyfish stock by 2023, representing a substantial loss of USD 3,934. Monthly catch data for 2022 further supported this, highlighting a fishing season from August to October, peaking in October (16,376kg) and continuing into December. To ensure the sustainability of the ponyfish population and fish processing industry, the fishing port authority should prioritize addressing the impact of overfishing practices, particularly trawling. Furthermore, continuous monitoring efforts are crucial to establish data-driven fisheries management practices. [ABSTRACT FROM AUTHOR]

To accurately identify the key features influencing the fisheries distribution of Pacific yellowfin tuna, this study analyzed data from 43 longline fishing vessels operated from 2008 to 2019. These vessels operated in the Pacific Ocean region (0° to 30° S; 110° E to 170° W), with a specific focus on 25 features of yellowfin tuna derived from marine environment data. For this purpose, this study opted for the Lasso regression analysis method to select features to predict Pacific yellowfin tuna fishing grounds, exploring the relationship between the catch per unit effort (CPUE) of yellowfin tuna and multiple features. This study reveals that latitude and water temperature at various depths, particularly the sea surface temperature of the preceding and subsequent months and the temperature at depths between 300 and 450 m, are the most significant features influencing CPUE. Additionally, chlorophyll concentration and large-scale climate indices (ONI and NPGIO) also have a notable impact on the distribution of CPUE for yellowfin tuna. Lasso regression effectively identifies features that are significantly correlated with the CPUE of yellowfin tuna, thereby demonstrating superior fit and predictive accuracy in comparison with other models. It provides a suitable methodological approach for selecting fishing ground features of yellowfin tuna in the Pacific Ocean. [ABSTRACT FROM AUTHOR]

The paper presents the results of the sterlet sturgeon Acipenser ruthenus reintroduction into the Kama Reservoir (Perm Krai, Russia) by sterlet fry from hatcheries into the reservoir since 2001. The effectiveness of hatchery releases was evaluated by monitoring gillnet sampling 2014–2020. The results showed that the species was reported throughout entire Kama Reservoir, which contrasts with 1988–1994 data, when the species was registered only at the upper part of the reservoir near the Kama River mouth. The highest number and biomass values of catch per unit effort (CPUE) of the sterlet were found in submerged river channels – the deepest habitats with flow conditions which are close to the ecological requirements of the species. The distribution of the sterlet within the channel biotopes of the reservoir is defined by reduced variability. The biggest individuals and the widest size range of the sterlet were typical for the upper area of the reservoir and Chusovskoy Bay, which have the greatest flow. The smallest sizes were typical for fish from catches near the dam of the reservoir, which is consistent with the published data on the distribution of sterlet in reservoir conditions. The presented results may indicate the artificial formation of the sterlet stock in the Kama Reservoir maintained by hatchery releases. The revealed distribution of the sterlet in the reservoir determines the direction of further research on natural reproduction and thus formation of an artificially formed population. Also, future studies are required to assess the possibility of hybridization of the sterlet of artificial origin with natural populations of the species, since the low genetic diversity of the sterlet released into the Kama Reservoir which can lead to irreversible loss of genetic individuality of the natural stocks of the species in the catchment of upper course of the Kama River.

Penangkapan ikan layang biru yang dilakukan secara terus-menerus, tidak terkontrol, dan tidak adanya proses rekruitmen akan menyebabkan stok ikan mengalami degradasi. Sebagian besar stok ikan layang biru saat ini bergantung pada sumber daya alam, yang menyebabkan stok dan kelimpahan ikan tidak stabil, jika ditangkap tanpa adanya pengelolaan yang baik. Oleh karena itu perlu dilakukan kajian terkait dengan pendugaan potensi lestari ikan layang biru. Penelitian ini bertujuan untuk menghitung Catch Per Unit Effort (CPUE), mengkaji nilai Maximum Sustainable Yield (MSY), dan Total Allowable Catch (TAC/JTB) ikan layang biru. Penelitian dilaksanakan di PPN Sibolga dengan metode pengumpulan data secara survei, sementara metode surplus produksi dianalisis dengan model Schaefer. Hasil penelitian diperoleh bahwa nilai CPUE standarisasi pada 2018 sebesar 0,639 ton/trip, pada 2019 mengalami peningkatan menjadi 0,764 ton/trip, pada 2020 menurun menjadi 0,527 ton/trip, pada 2021 menjadi 0,506 ton/trip, dan pada 2022 meningkat menjadi 0,639 ton/trip. Alat tangkap pukat cincin merupakan alat tangkap yang paling berperan dalam sumber daya ikan layang biru. Sementara itu, nilai CMSY dengan menggunakan model scheafer diperoleh 8.699,7 sehingga disimpulkan bahwa status penangkapannya sudah fully exploited. Sedangkan nilai FMSY diperoleh sebesar 5.447 trip, dimana statusnya sudah overfishing karena upaya penangkapan setiap tahunnya sudah berada di atas nilai FMSY. Jumlah tangkapan yang diperbolehkan (TAC/JTB) sebesar 6.959,7 ton.

The fishery biology of the invasive Atlantic blue crab Callinectes sapidus in the Mediterranean Sea outside the eastern sectors of the basin has been only recently investigated. Here we studied the population of C. sapidus in the Lesina Lagoon (Adriatic Sea, SE Italy). In total, 838 crabs were captured monthly between February 2021 and January 2022 using fyke nets. Abundances varied seasonally with catches per unit effort ranging between 0 and 1.76 crabs fyke nets−1 d−1 in winter and summer. Spatial abundances estimated in summer by a Carle–Strub procedure ranged between 0.06 and 0.64 crabs m−2. The sex ratio (♂/♀) was close to 1:1; males prevailed only in August and September; ovigerous females occurred from April to August. The males’ size at morphological maturity was smaller than females (110.6–112.3 mm vs. 122.1–123.1 mm). Seasonal von Bertalanffy growth parameters indicated that, compared with males, females showed a shorter maximum lifespan (5 vs. 8 years), a higher growth coefficient K (0.6 vs. 0.4 y−1) and growth performance index Ф’ (4.6 vs. 4.3), while maximum sizes CW∞ (237.8 vs. 232.6 mm) and seasonality indices C (0.62 vs. 0.57) were similar. Furthermore, females showed higher natural and fishing mortalities and exploitation rate. We discussed the results of the present study in the context of the available literature to provide a valuable basis for the implementation of standardized Mediterranean-scale management plans, matching exploitation of C. sapidus with sustainable conservation of coastal ecosystems.

Copyright of South China Fisheries Science is the property of South China Fisheries Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Antarctic krill is a pivotal species in the Southern Ocean ecosystem, primarily due to its extraordinary nutritional content and plentiful resources. Studying the distribution of these resources and their environmental impact factors is crucial for the successful development of Antarctic krill fisheries. Traditional methodologies such as acoustic measurements, however, often face limitations in their capacity to provide a comprehensive and uninterrupted assessment. Moreover, the six-month duration of polar nights in polar regions presents significant challenges for traditional satellite observations. In this context, LiDAR, an active remote sensing observation method, offers a promising alternative. Known for their high resolution, flexibility, and efficiency, LiDAR systems can obtain detailed information on diurnal ocean parameters in polar regions on a vast scale and in a systematic way. Our study utilizes the spaceborne LiDAR system, CALIPSO, to successfully attain continuous Antarctic krill CPUE over the past decade, using various models such as the generalized linear model (GLM), artificial neural network (ANN), and support vector machine (SVM). A comparative analysis of the prediction results reveals that while both ANN and SVM models outperform the GLM, the SVM's prediction capabilities are somewhat unstable. Our findings reveal CALIPSO's potential in overcoming challenges associated with traditional satellite observations during polar winters. In addition, we found no obvious pattern of interannual variation in krill CPUE, with high values predominantly occurring from February to May. This suggests that krill is mainly located around the South Shetland Islands during January-April, before moving offshore towards South Georgia in May-June. A substantial krill aggregation community is found in the South Atlantic waters, indicating high potential for krill fishing. The optimum mix layer depth range for high krill CPUE is 270-390 m, with a chlorophyll concentration of approximately 0.1 mg m-3. The optimum sea surface temperature range is between -1.4-5.5°C, and the sea ice coverage range is approximately 0-0.1×106 km². The predicted Antarctic krill bioresource has risen from 2.4×108 tons in 2011 to 2.8×108 tons in 2020. This increase in krill biomass aligns with the biomass of krill assessed by CCAMLR. [ABSTRACT FROM AUTHOR]

The paper presents the results of the sterlet sturgeon Acipenser ruthenus reintroduction into the Kama Reservoir (Perm Krai, Russia) by sterlet fry from hatcheries into the reservoir since 2001. The effectiveness of hatchery releases was evaluated by monitoring gillnet sampling 2014-2020. The results showed that the species was reported throughout entire Kama Reservoir, which contrasts with 1988-1994 data, when the species was registered only at the upper part of the reservoir near the Kama River mouth. The highest number and biomass values of catch per unit effort (CPUE) of the sterlet were found in submerged river channels - the deepest habitats with flow conditions which are close to the ecological requirements of the species. The distribution of the sterlet within the channel biotopes of the reservoir is defined by reduced variability. The biggest individuals and the widest size range of the sterlet were typical for the upper area of the reservoir and Chusovskoy Bay, which have the greatest flow. The smallest sizes were typical for fish from catches near the dam of the reservoir, which is consistent with the published data on the distribution of sterlet in reservoir conditions. The presented results may indicate the artificial formation of the sterlet stock in the Kama Reservoir maintained by hatchery releases. The revealed distribution of the sterlet in the reservoir determines the direction of further research on natural reproduction and thus formation of an artificially formed population. Also, future studies are required to assess the possibility of hybridization of the sterlet of artificial origin with natural populations of the species, since the low genetic diversity of the sterlet released into the Kama Reservoir which can lead to irreversible loss of genetic individuality of the natural stocks of the species in the catchment of upper course of the Kama River. [ABSTRACT FROM AUTHOR]

Motor and outboard boats are the main means by which fishersmen exploit the fisheries resources in these waters. The success of the catch and the efficiency of the fishermen's efforts are strongly influenced by various factors related to the characteristics of the boat, the fishing gear and the condition of the aquatic environment. This study aims to analyse the determinants of catch and catch per unit effort of motorboat and outboard motorboat fishers in bulukumba regency. Data collection techniques used were observation, interview and documentation. The number of samples was 81 modern fishermen (juragan fishermen) of motorboats out of 407 population using the Slovin formula method and 81 outboard motorboat fishermen out of 81 population using the area proportional random sampling method. Data analysis techniques used are statistical tests, classical assumptions tests using SPSS 25 and CPUE analysis. The study found that the length of fishing (X1), volume of diesel (X2), age of fishermen (X4), and fishing experience (X6) had a positive impact on the production of motorboat fishermen's catch (Y1) when examined independently. On the other hand, the number of labour (X3) and formal education of fishermen (X5) were negatively correlated with catch production. The duration of sea time (X7) and the power of the outboard engine (X8) have a positive impact, whereas the volume of petrol (X9), age of fishermen (X10), formal education of fishermen (X11), sea experience (X12), and number of fishing gear used (X13) have a negative impact on the catch rate of outboard motorboat fishermen (Y2). Based on the CPUE (Catch per Unit Effort) value, there has been a fluctuation of motorboat and outboard motorboat fishermen from 2017 to 2021. The average value per year, from 2017 to 2021, was 389.9914kg/trip for motorboat fishermen and 46.66028kg/trip for outboard motorboats. It is recommended to increase the number of fishing gear, particularly trawl gear, and transportation facilities in fishing. Fishers should be incentivised to utilise fishing equipment that is appropriate for the specific kind of fish and local aquatic environments in order to enhance catches and reduce negative impacts on fishing resources. [ABSTRACT FROM AUTHOR]

Scylla spp. are among the most economically important fisheries resources derived from the mangroves. However, the widespread mangrove destruction resulted in the loss of habitat, thus the dwindling capture production of many mangrove‐associated faunas. Although studies have shown that Scylla populations have reestablished in mangrove‐reforested areas, this study was the first in a mangrove‐recolonized abandoned pond in the Philippines. Six fishers conducted standardized fishing every spring tide of the month using cylindrical bamboo traps. All crabs caught from July 2010 to December 2011 were recorded for species, sex, sexual maturation of females, carapace width (CW), and body weight (BW). Total landings comprised 14,262 crabs weighing 1,743 kg; 79.67% Scylla olivacea, 20.18% S. tranquebarica, and 0.15% S. serrata. CW ranged 3.1–17.1 cm and BW 10–1,250 g, with the male crabs comprising 39.23–64.65% of the monthly landings and the females distributed as 19.88–45.01% immature, 0.50–16.57% mature, 0.45–16.02% gravid, and less than 0.10% spent crabs. Monthly landings ranged 254–1,231 pcs of crabs or 32.38–160.59 kg. The monthly mean catch per unit effort (CPUE), in terms of number, was 0.101 ± 0.01–0.456 ± 0.02 crab gear−1 day−1 (max = 1.13), while in terms of biomass, 12.86 ± 0.84–54.36 ± 3.16 g gear−1 day−1 (max = 112.50). Length–weight relationships of S. olivacea and S. tranquebarica are expressed as W = 0.224967L2.9864 (r2 = 94.08%, p < 0.001; n = 11,363) and W = 0.173409L3.1074 (r2 = 92.71%, p < 0.001; n = 2,878), respectively. This study revealed that Scylla spp. could reestablish in mangrove‐recolonized abandoned ponds. [ABSTRACT FROM AUTHOR]

A new conceptual framework based on satellite data, including chlorophyll (CHL), sea surface temperature (SST) fronts, relative winds, current vectors, Ekman transport, and eddies, has been developed to identify potential fishing zones (PFZ) in the Bay of Bengal (BoB). The framework aims to provide persistent forecasts, even under cloudy conditions, based on feature propagation. The validation of the PFZ was carried out using fish catch data collected by the Fishery Survey of India (FSI) between 2016 and 2018. Hooking rates (HR) from longlines and catch per unit effort (CPUE) from trawl nets were used to analyse the data points in hook rate categories (1.0–3.0 and > 3.0) and CPUE categories (50–100 kg and > 100 kg) and interpret them with the PFZ maps. The analysis showed that the high fish catch locations were consistent with persisting features in the BoB, such as high chlorophyll patches, SST fronts, and cyclonic eddies. The high fish catch locations based on hook rate and high CPUE were found to be collocated with the high chlorophyll persisting features and thermal gradients in the BoB. The regression analysis shows that availability of the food (CHL) had the strongest correlation with fish catch, followed by the comfort condition (fronts and eddies). [ABSTRACT FROM AUTHOR]

Ethiopia's largest freshwater lake, Lake Tana, is home to 21 endemic fish species, the majority of which are cyprinids in the genus Labeobarbus. The lake is undergoing numerous ecological changes, including an invasion of water hyacinth (Eichhornia crassipes (Mart.) Solms (WH). The aim of this study was to predict the future fish productivity in Lake Tana by considering the increasing water hyacinth infestation. This was accomplished by analyzing a 12-year fishery-independent time-series data set of Labeobarbus, collected from sites infested and not infested by water hyacinth. The stationarity of the data was investigated using the Augmented Dickey-Fuller (ADF) unit root test. First-order data differencing was applied to solve the non-stationarity data to stationarity. With the same standardized fishing gillnet and the same sites, the CPUE during the dry season decreased from 3,502 grams (3.5 kg/day) in 2010 to 360 grams (0.36 kg) in 2020 at the water hyacinth-infested sites, demonstrating a 90% decrease in the daily catch. A reduction in catch per unit effort (CPUE) is evident at the WH sites in all seasons, and the rate of fall in there was faster than at the non-infested site. Box Jenkin's auto-regressive integrated moving average models (ARIMA) modelling predicted that Labeobarbus CPUE will decline by a threefold % by 2032 compared to the current catch. Based on these results, the most suitable model for all the seasons and areas was confirmed to be ARIMA (0, 1, 0) using the lowest value of Akaike Information Criteria (AIC's). The fish production declines with expanding WH infestation will necessitate integrated water hyacinth reduction strategies, closed area and closed spawning seasons, and mesh size regulations to conserve and utilize the resource sustainably. As Labeobarbus is the only examined species in this study, forecasts should be made for other commercially significant fish species in the Lake, such as Oreochromis niloticus and Clarias gariepinus. [ABSTRACT FROM AUTHOR]

The octopus fishery is of major economic interest in the Moroccan Mediterranean, exploited by fishing boats using mainly octopus jigs and coastal trawlers using atomic bottom trawls. The current study, carried out in 2019, aims to quantify and characterize the nominal and effective fishing effort by fleet, and to assess the exploitation level in the octopus fishery using surveys with fishermen and catch and fishing effort data analysis. Respectively for artisanal boats and coastal trawlers, the depth of exploited areas was 24.7 m and 110 m (between Hoceima and Saidia), 124 m (between Fnideq and Cala Iris). Likewise, the annual fishing effort was 45,592 days (35,346 effective days) and 6385 days (3467 effective days). The fishing effort conversion factors were 0.78 and 0.54, proving that artisanal boats are more efficient than coastal trawlers in terms of time strictly dedicated to fishing. The total standardized annual fishing effort (FT) was 69,394 fishing days (53,799 effective days). The changing relationship Catch-FT during 2010–2019 was analyzed using linear regression Catch = 1,063,728.02 + 28.1FT (R2 = 0.55), implying that the Maximum Sustainable Yield was exceeded since 2015. Catch per Unit Effort (CPUE) was influenced by FT, Gear, and Year variables as demonstrated by the multiple regression equation: CPUE =− 14,299 − 0.0012FT + 7.17Year − 22.82Gear (R2 = 0.82). These results might serve as baseline data in population dynamic studies contributing to octopus fishery management. [ABSTRACT FROM AUTHOR]

Effective management of inland capture fisheries requires information about size, growth and mortality parameters and catch per unit effort. The estimated slope b values for three cyprinids were found to be within the expected range and r2 showed high degree of correlation. The estimated growth parameters of Mirgal, Cirrhinus mrigala (Hamiltoon, 1832) (L8 89.25 cm, K 0.8y-1), Blackspot barb, Dawkinsia filamentosa (Valenciennes, 1844) (L8 22.05 cm, K 0.68y-1) and Roho labeo, Labeo rohita (Hamilton, 1822) (L8 47.25 cm, K 0.71y-1) and the mortality parameters of C.mrigala (Z 2.14 y-1, M 1.22 y-1 and F 0.92 y-1), D. filamentosa (Z 2.42 y-1, M 1.54 y-1 and F 0.88 y-1) and L. rohita (Z 2.87 y-1, M 1.42 y-1 and F 1.46 y-1). The estimated exploitation ratios (E) for the three species were 0.43, 0.36 and 0.51, respectively. The mean CPUE was 0.9136 kg / hr / craft. This study would suggest good inland capture fishery management plan in the potamon zone of the river Thamirabarani. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Dalian Ocean University is the property of Journal of Dalian Ocean University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Bigeye tuna (BET) and yellowfin tuna (YFT) are economically important target species of pelagic fisheries worldwide, especially for tropical Pacific nations whose economies and food sources are heavily affected by commercial and sustenance tuna fishing. The El Niño‐Southern Oscillation (ENSO) has a strong effect on the oceanographic conditions in the equatorial Pacific, including BET and YFT equatorial habitat and fishing grounds. For optimal fisheries management, the effects of environmental variability such as ENSO on the stocks and on the performance of fisheries must be known and predictable. However, besides some model predictions, the effects of ENSO on these two tuna species are not well understood. In this study, I investigate the statistical relationships between past ENSO conditions and equatorial fisheries using the Multivariate ENSO Index, sea surface temperature (SST), and catch and effort records from the longline fisheries in the region. Results of this study indicate that El Niño events have both delayed and concurrent positive effects on BET and YFT catch per unit effort (CPUE). The delayed positive ENSO effect on CPUE is hypothesized to be the result of enhanced recruitment acting via different mechanisms in the west than in the east. The concurrent positive effects on CPUE could be due to catchability, abundance, and/or vertical distribution of BET and YFT relative to fishing gear and require further investigation. Further exploration of the mechanisms that may underlie the results presented here could lead to predictability of CPUE of these two tuna species. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agriculture & Nature / Kahramanmaraş Sütçü İmam Üniversitesi Tarım & Doğa Dergisi is the property of Kahramanmaras Sutcu Imam Universitesi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Support for eDNA as a quantitative monitoring tool is growing worldwide. Despite advances, there are still uncertainties regarding the representability of the eDNA signal over varying spatiotemporal scales, the influence of abiotic forcing, and phenological changes affecting the behavior of the study organism, particularly in open environments. To assess the spatiotemporal variability and predictive power of quantitative eDNA analysis, we applied species‐specific real‐time quantitative PCR on water filtrates during two visits to 22 coastal bays in the Baltic Sea. Within bays, we collected water along four transects across each bay and compared the pooled eDNA concentration to temporally matched catches from standardized angling targeting the northern pike (Esox lucius), a species for which reliable monitoring data is lacking. We found the variability in eDNA concentrations between transects to be moderate (21%) but still considerably lower than across bays and visits (52%), suggesting small‐scale spatial differences are of less importance during spring when pike spawn. Standardized angling catches, bay area, and water temperature together explained 48% of the variance in eDNA concentrations. DNA concentrations decreased with the increasing bay area, likely indicating a dilution effect. Notably, the relationship between eDNA and standardized catches was positive but varied with temperature and the eDNA‐abundance relationship was only significant at higher temperatures, which also coincided with a higher proportion of spawning/spent fish. We conclude that temperature is a key moderating factor driving changes in pike behavior and spring DNA‐dynamics. We recommend that future surveys focus on larger spatiotemporal scales during times when the influence of changing temperatures is minimized.

Statistical estimates for the exploitable stock of giant grenadier are determined, by fishing zones in the Russian Far East, and interannual dynamics of the species biomass is considered using historical data on catches and abundance. The assessments relationship with reference points of the biomass dynamic models is examined for the first time. With using the Bayesian approach, a priori assumptions about virgin biomass, which were made earlier on results of scientific surveys extrapolated to unsurveyed areas, are accounted in JABBA model; some errors in the catch and abundance indices are revealed. The parameters of instantaneous rate of recruitment and initial depletion of population are determined. Overfishing is not detected yet in any fishing zone, but a negative trend of the biomass dynamics is noticed for the Western Bering Sea fishing zone since 2015 (if the stock estimations based on surveys are realistic). The decline is reasoned by implementation of too high target for exploitation rate of vulnerable biomass (φF = 0.10) that is higher than such target for other fishing zones (< 0.08 or even 0.01 for the stocks exploited with the total allowable catch limits). That’s why annual catches exceeded the surplus production in the Western Bering Sea fishing zone in 2012 and since 2015 to nowadays. The sum of median estimations for the maximum sustainable yields in all fishing zones is about 47.4 . 103 t that exceeds the values of total annual catch. The instantaneous rate of recruitment is almost equal in the neighboring fishing zones in the western Bering Sea and at East Kamchatka (0.086–0.085 by median, with 95 % credible intervals from 0.05 to 0.14) and is much higher at Kuril Islands with the maximum in the North-Kuril fishing zone. The latter case is possibly conditioned by partially external recruitment. Therefore, population structure of giant grenadier should be clarified for correct modeling of the recruitment; until then, the stocks assessments by fishing zones are available.

Abstract The solunar theory proposes that the position of the sun and moon can be used to predict activity rates in fish and game species. Several free and premium services use this theory to provide tables predicting optimal dates and times for fishing and hunting success. The efficacy of these services was tested by comparing catch per unit effort (CPUE) in a recreational freshwater trout fishery with daily solunar values and coincidence of fishing trips with peak solunar times. CPUE was also compared to environmental variables including lunar phase, lunar illumination, and wind speed. Values predicted by each of the solunar services were strongly correlated to each other and to lunar phase, however, no significant relationship was found between CPUE and any of the solunar values tested, lunar phase, or lunar illumination. Ambient air temperature showed a positive relationship with CPUE, and was a more effective predictor of fishing success than any of the solunar tables tested.

To accurately identify the key features influencing the fisheries distribution of Pacific yellowfin tuna, this study analyzed data from 43 longline fishing vessels operated from 2008 to 2019. These vessels operated in the Pacific Ocean region (0° to 30° S; 110° E to 170° W), with a specific focus on 25 features of yellowfin tuna derived from marine environment data. For this purpose, this study opted for the Lasso regression analysis method to select features to predict Pacific yellowfin tuna fishing grounds, exploring the relationship between the catch per unit effort (CPUE) of yellowfin tuna and multiple features. This study reveals that latitude and water temperature at various depths, particularly the sea surface temperature of the preceding and subsequent months and the temperature at depths between 300 and 450 m, are the most significant features influencing CPUE. Additionally, chlorophyll concentration and large-scale climate indices (ONI and NPGIO) also have a notable impact on the distribution of CPUE for yellowfin tuna. Lasso regression effectively identifies features that are significantly correlated with the CPUE of yellowfin tuna, thereby demonstrating superior fit and predictive accuracy in comparison with other models. It provides a suitable methodological approach for selecting fishing ground features of yellowfin tuna in the Pacific Ocean.

A multi-mesh trammel net has been developed and used for sampling freshwater fishes. However, little is known about the catch efficiency of the net. This research investigated the catch efficiency of a multi-mesh trammel net (nominal mesh size; 10.0, 30.0, 50.0, and 70.0 mm) for fish sampling in the Yangtze River of China. Catch composition and factors affecting catch per unit effort based on fish number (CPUEN), weight (CPUEW), and species number (CPUES) were analyzed. The results showed that the net was capable of capturing a wide range of fish sizes (total length, 5.5 to 121.0 cm) and species (n = 50). Increasing soak time from 9.4 to 24.0 h resulted in a decrease in CPUEN and CPUEW while a longer soak time increased CPUES. CPUEN, CPUEW, and CPUES varied significantly with fishing locations. The net provides a potential complement to the current fish sampling techniques used in freshwater ecosystems (e.g., large rivers, lakes, and reservoirs). The findings of this research help to improve our understanding of the catch efficiency of the multi-mesh trammel net and provides insight into better designs for gears and methods for sampling diverse fish sizes and species. [ABSTRACT FROM AUTHOR]

The size of chum salmon juveniles is crucial to their survival. In order to understand the population status and migration patterns of juvenile chum salmon in the waters of the Amur River in China, this study investigated the status of juvenile chum salmon resources and their basic biological characteristics in the Amur River and the Ussuri River in China. The results showed that the average catch per unit effort (CPUE) of chum salmon in river margins was 0.140 ind·10−3 m3 for the Amur River and 0.255 ind·10−3 m3 for the Ussuri River. Chum salmon migrate downstream, mainly in mid-May in the Amur River and in early May in the Ussuri River, and no fish was caught in the rivers after June. Most chum salmon migrated when the water was between 10 and 14 °C. The average FL (fork length) and BW (body weight) of the Amur River samples were 37.1 ± 2.9 mm and 0.42 ± 0.09 g, respectively, while the Ussuri River samples' FL and BW were 34.9 ± 3.7 mm and 0.36 ± 0.08 g, respectively. The empty stomach rate of the samples was zero, and the prey category of the samples was composed of fish, aquatic insects, copepods, and cladocerans, of which Ephemeroptera had the largest percentage index of relative importance (IRI%), with a value of 58.45%. The size of the downstream-migrating juvenile chum salmon in this study is similar to the size of those in some other rivers, and the CPUE varies depending on the river conditions. [ABSTRACT FROM AUTHOR]

Development and growth rate variations during early life are important for understanding the mechanisms of recruitment dynamics. We examined the larval growth rate and age at the onset of metamorphosis (dm) of juvenile Japanese jack mackerel recruited to a population in the Uwa Sea, Japan. Otolith microstructure analyses revealed that the hatch date of juveniles ranged from February to April in 2011–2015, and that their dm were 25.5–30.5 days and mean growth rates at the larval stage (GL) were 0.30–0.34 mm day−1. Among dm and GL, dm showed significant negative correlations with juvenile abundance. Moreover, the hatch date did not coincide with the spawning period of this species in the Uwa Sea, and the hatch date and mean growth rate at the larval stage were comparable to those of Japanese jack mackerel juveniles sampled in the East China Sea (ECS). These findings suggest that most juvenile Japanese jack mackerel originated in other waters, including the ECS, and that larval stage duration influenced their recruitment abundance in the Uwa Sea. [ABSTRACT FROM AUTHOR]

Context: Introduced sambar deer (Cervus unicolor) are increasing in south-eastern Australia, and both volunteer and contract ground-based shooters are being used by management agencies to control their undesirable impacts. However, little is known about the effectiveness and costs of volunteer and contract shooters for controlling deer populations in Australia. Aims: We evaluated the effectiveness and costs of volunteer and contract ground-based shooters for controlling sambar deer and their impacts in a 5-year management program conducted in and around alpine peatlands in Alpine National Park, Victoria. Methods: Ground-based shooting operations were organised in two blocks. Within each block, four ~4200-ha management units were delimited, of which two were randomly assigned as treatment (ground-based shooting) and two as non-treatment (no organised ground-based shooting). In the treatment units, ground-based shooting was conducted using either volunteers or contractors. Each shooting team recorded their effort and the numbers of deer seen and shot, and used a GPS to record their track log and the time and locations of deer shot. Key costs were recorded for both shooter types. Key results: The catch per unit effort of contract shooters was four times greater than that of volunteer shooters. Both shooter types were most effective during the first half of the night and prior to sunrise, and when using a vehicle with a spotlight or walking with thermal-vision equipment. During the day, the use of gundogs to indicate deer significantly increased the success rate of volunteer shooters. Both volunteer and contract shooters used roads and tracks to move in the landscape, but contractors covered more ground than did volunteers. After accounting for key operational costs, the cost per deer killed was 10.1% higher for contract than volunteer shooters. Conclusions: The effectiveness of ground-based shooters is increased by operating at night using vehicles, spotlights and thermal-vision equipment. Contract shooters kill sambar deer at a faster rate, but are slightly more expensive per deer killed, than are volunteer shooters. Implications: Ground-based shooting is likely to be most effective when conducted at night with thermal-vision equipment, and in areas with a high density of roads and tracks. Ground-based shooting is widely used to reduce the undesirable impacts of deer, but the effectiveness and costs of this technique have seldom been quantified in Australasia. We evaluated the cost-effectiveness of volunteer and contract ground-based shooters for controlling sambar deer in a 5-year management program in eastern Australia. Our study showed that the catch per unit effort of contract shooters was four times greater than that of volunteers, but that cost per unit killed was 10.1% greater for contract shooters. Photograph by Parks Victoria. [ABSTRACT FROM AUTHOR]

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The aim of this research is to analyse the trends of the total artisanal fish catch in the Croatian section of the Sava River. All 17 years of the study (2004-2020) showed a negative trend that became highly statistically significant (p

The marine environment has distinct seasonal characteristics in the northwestern South China Sea, under the influence of monsoons, tides, wind stress, and coastal runoff. Decapterus maruadsi is an economically important pelagic fish along the southeast coast and is highly sensitive to the external environment. It is mainly distributed along the coast of the Beibu Gulf and in the waters of western and eastern Guangdong, with abundant resources. To understand the environmental driving mechanisms of D. maruadsi in the northwestern South China Sea, the in-situ fishery data and marine environmental remote sensing data in the northwestern South China Sea from 2012 to 2018 were used to analyze the spatio-temporal distribution of the seasonal average catch per unit effort (CPUE) of D. maruadsi using a generalized additive model. The results showed that the CPUE of D. maruadsi was related to the longitude, sea surface temperature (SST), chlorophyll a (Chl-a) concentration, depth of water, sea surface salinity (SSS), mean direction of total swell, mean direction of wind waves, and mean period of wind waves. The mean direction of wind waves contributed the most to CPUE, followed by the mean direction of the total swell and SST. D. maruadsi occurred mainly in a small area, from longitude 110.5°~114°E, SST 26~30℃, Chl-a 0.2~1.0 mg/m3, depth of water < 120 m, SSS 33.4~33.8, mean direction of total swell 70°~120°, 150°~175°, mean direction of wind waves 50°~75°, 120°~135°, 175°~190° and mean period of wind waves 3.0~4.5 s. Moreover, the SST with high CPUE changed significantly withinseasons, contrary to Chl-a. The CPUE of D. maruadsi had obvious seasonal characteristics, with the highest value of 0.848 kg/(kW·d) in summer and the lowest value of 0.087 kg/(kW·d) in winter. The abnormal increase in CPUE in 2016 may have been due to the impact of a super strong El Niño event in 2015–2016. The months in which the sea surface temperature anomaly (SSTA) exceeding 2.5℃ lasted from October 2015 to January 2016, and the spawning period of D. maruadsi is mainly winter and spring, which explains why the CPUE of D. maruadsi began to increase in the winter of 2015. Thus, the super strong El Niño had a positive impact on the replenishment of D. maruadsi in 2016. In this study, the effects of the wind waves and total swell were included in the model for the first time, and we found that wind waves and swells in a certain direction were conducive to the aggregation of D. maruadsi. This may have been due to the south and southwest winds and swells associated with upwelling activity in the northern South China Sea. The changes in the marine environment of the South China Sea are closely related to the ocean dynamics caused by monsoons. To further understand the relationship between the spatio-temporal distribution of D. maruadsi and the marine environment, and to provide a scientific basis for the conservation and adaptive management of D. maruadsi in the northern South China Sea, we can consider adding more representative ocean dynamic factors (such as sea surface and bottom velocities, mixed layer depths, and vertical velocities) to the model, to characterize different dynamic processes and to study the changes in abundance of this fish.

In this study, the catch composition and catch productivity of bottom trawl shrimp fishery in the North East Mediterranean were determined with respect to season, location, depth and distance from the coast for a period of 1 year. The study was carried out along a 200 km transect at five different stations and a total of 40 trawl operations with 153 hours and 2 minutes of active trawling was performed. During the study, a total of 11 shrimp species, six of which have economic value, (Penaeus semisulcatus, Metapenaeus monoceros, Marsupenaeus japonicus, Melicertus kerathurus, Metapenaeus stebbingi, Parapenaeus longirostris, Trachypenaeus curvirostris, Alpheus glaber, Palaemon serratus, Palaemon adspersus, Aegaeon cataphractus) were captured belonging to four families (Penaeidae, Alpheidae, Crangonidae, Palaemonidae). The most abundant species was P. semisulcatus (CPUE: 0.748 kg/h and 19.26 kg/km2) with a catch rate of 50.26%, followed by P. longirostris (35.05%; CPUE: 0.521kg/h and 13.41 kg/km2) and M. monoceros (11.29%; CPUE: 0.168 kg/h and 4.32 kg/km2). Considering the total catch of all shrimp species, the CPUE value was calculated to be 1.49 kg/h and 38.25 kg/km2. Catch composition with respect to distance from the coast indicated that the P. semisulcatus had the highest catch rate (80.53%) within 0-3 mile zone, whereas P. longirostris had the highest catch rate (67.40%) within 3-10 mile zone.

This study examined the spatial distribution of mature albacore tuna (Thunnus alalunga) in the Indian Ocean between 1998 and 2016 (October to March) using environmental factors and logbook fishery data from Taiwanese longliners. We collected the albacore tuna fishery data, including fishing location, fishing effort, number of catch, fishing duration, and fish weight. The optimal limits for oxygen, temperature, salinity, and sea surface height for mature albacore tuna, as determined by generalized additive modeling, were 5–5.3 mL/L, 25–29°C, 34.85–35.55 PSU, and 0.5–0.7 m, respectively. The optimal models were determined to be a geometric mean–derived habitat suitability–based model constructed with oxygen, temperature, and salinity and a generalized additive model constructed with oxygen, temperature, salinity, and sea surface height. From October to March, mature albacore tuna remained between 10°S and 30°S. Our study concurs with previous studies on albacore tuna in the region that suggest that the spawning area is located between 10-25˚S, and that spawning occurs primarily between November and January. This study reveals the spatial patterns and environmental preferences of mature albacore tuna in the Indian Ocean which may help put in place better management practices for this fishery.