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The paper studies populations of the Dolly Varden charr from some rivers in eastern Kamchatka in 2005–2007. Generally small variability is noted in biological parameters (length, weight, age, and sex composition), however, significant variability is revealed in size of individuals within age groups. Long-period cycles are marked in the dynamics of catches. The periodicity of catches of charr in different areas of east Kamchatka in general terms is the same, which gives reason to summarize the nature of its population dynamics in the whole coast.

The current study was carried out on Okpara Stream in Northern Benin to evaluate the demographic factors with inferences on fisheries status of five dominant fish species, which were sampled monthly intervals for 18 months. Asymptotic length (Lro) ranged from 36.23 cm (Brycinus macrolepidotus) to 18.8 cm (Hemichromis fasciatus). Growth rates (K) varied between 1.6 yr-1 and 0.66 yr-1 with growth performance index (Φ') ranging from 2.4 to 3.1. Theoretical age at length zero (t0) varied -0.95 year for Marcusenius senegalensis to -0.59 year for Shilbe intermedius. Except for B. macolepidotus, total mortalities were higher than 2 year-1 and length at first capture (L50) ranged 7.72-12.09 cm. Marcusenius senegalensis and S intermedius showed one annual peak of recruitment, whereas H fasciatus, Oreochromis niloticus and B. macrolepidotus displayed two peaks. The results indicated that the stocks of these five species were underexploited. However, the low length at first capture (L50) recorded for some species, requires the implementation of early fisheries management scheme to assure a sustainable exploitation of these fishes.

This study analyzed the population parameters of yellowtail fusilier (Caesio cuning) in Karimunjawa waters to inform strategies for sustainable management. Sampling was carried out over 13 months (July 2024-July 2025) at major fish trading centers on Karimunjawa and Kemujan Islands. A total of 1,583 individuals were measured for total length (TL, cm) and body weight (W, g) to estimate growth parameters, exploitation rates, and recruitment patterns. The results showed a negative allometric length–weight relationship. The length at first capture (Lc50%) was 19.8 cm TL, the growth coefficient (K) was 0.86 per year, and the exploitation rate (E) was 0.61, exceeding the optimal limit (E = 0.5). These values indicate overexploitation. Recruitment analysis revealed a continuous year-round pattern, with a peak between May and June. Overall, the findings confirm that the C. cuning population in Karimunjawa Islands is experiencing high fishing pressure.

During the 1990s, all of the European transition economies (TE) experienced a major recession and suffered from the explosion of income inequality. However, distribution of income between labor and capital differed greatly from one group of post-communist countries to another. The paper discusses and analyzes linkages between models of capitalism that emerged in former communist countries in the 1990s and the outcome of capitalist transition for labor in terms of income distribution and inequality. It is based on the estimates of the Marxian rate of exploitation and other indicators of labor income performance during the reform period.

This study analyzed the utilization status of the blue swimming crab (BSC) (Portunus pelagicus) in Kebumen coastal waters. Field research was conducted from October to December 2024. Biological characteristics related to growth and infinity carapace width (CWoo) were assessed, along with mortality and exploitation rates. Results showed a carapace width (CW) at 50% capture (CWc 50%) of 11.95 cm and a CWo of 18.38 cm. Peak BSC recruitment occurred in May. An exploitation rate of 0.31 indicates that the BSC population in Kebumen coastal waters is currently underexploited.

To investigate the age composition, growth pattern, mortality, and exploitation rate of Triplophysa pseudoscleroptera in the upper reaches of the Yellow River, this study conducted four sampling surveys between 2022 and 2023 to measure the total body length ( L ) and body weight ( W ) of a total of 313 individuals. Age determination was performed using otoliths. The collected samples exhibited a total length ranging from 4.50 cm to 13.80 cm, body weight from 0.98 g to 19.38 g, and age range from 1 to 5 years old. The relationship between total length and body weight was described by W = 0.0082 L 2.9392 for all samples, indicating isometric relative growth pattern observed in this study. The von Bertalanffy growth equation revealed that T. pseudoscleroptera had an asymptotic total length L ∞ of approximately 18.10 cm with a growth coefficient k estimated as 0.209 yr −1 . The exploitation rate ( E ) is concurrently estimated to be 0.3873. The growth characteristic index of T. pseudoscleroptera is 1.8355; in comparison with other fish species within the same genus, it demonstrates a relatively sluggish overall growth rate. Compared with other Triplophysa fish, the growth rate of T. pseudoscleroptera in the upper reaches of the Yellow River appears to be relatively slow, and its mortality rate is predominantly influenced by fishing activities. Therefore, given the relatively high fishing mortality rate and the current situation in the Yellow River for T. pseudoscleroptera , it is imperative to implement locally tailored management strategies to safeguard the population of this species. These strategies should include measures to regulate the introduction of nonindigenous fish and establish regulations on the utilization of finer mesh fishing tools owing to their more obvious detrimental impact on small and medium-sized fish.

Golden rabbitfish ( Siganus guttatus ) is an important species to people in Wakatobi islands that are surrounded by the Banda Sea and the Flores Sea. They catch the fish for local consumptions and trade processed fish to other areas. This study aims to determine estimates of the fish's growth, mortality, and exploitation rates. The study was conducted from January to November 2016 in Wakatobi. Analysis was carried out the FISAT II package. The fish length ranged from 8.0 to 49.0 cm with an average of 26.19 cm. The growth pattern of male fish was positive allometric while for female fish was allometric negative. The sex ratio was inbalanced. The estimate of length at first capture (Lc) was 27.65 cm (FL) while the estimate of length at first maturity (Lm) was 30.49 cm (FL). The natural mortality (M) was 1.51/year while the fishing mortality was 1.28/year and the exploitation rate was 0.46/year. The SPR was 0.49, indicating the exploitation rate of Siganus guttatus in the studied areas is still at the optimum condition.

Population's biological parameters, including length at first capture, mortalities, exploitation rates, growth coefficient, longevity, and recruitment times, are essential in assessing fishing status, but there is no data on Mystus mysticetus. Therefore, the study was conducted to provide these parameters to assess the fishing status of this species at Cai Rang, Can Tho (CRCT) and Long Phu, Soc Trang (LPST). A collection of 741 individual fish was used for analysis and showed that most fish size groups ranged from 9.0 cm to 12.0 cm, and the asymptotic length was 16.8 cm for both CRCT and LPST populations. The fish population von Bertalanffy curve was Lt = 16.80(1 − e−0.51(t + 0.38)) at CRCT and Lt = 16.80(1 − e−0.48(t + 0.40)) at LPST. The fish growth coefficient at CRCT (2.16) was higher than at LPST (2.13), whereas the reverse case was true for longevity ranging from 5.88 years (at CRCT) to 6.25 years (at LPST). At CRCT, fishing mortality, natural mortality, total mortality, and exploitation rate were 0.69/year, 1.40/year, 2.09/year, and 0.33, respectively; at LPST, these values were 0.75/year, 1.33/year, 2.08/year, and 0.36, respectively. Although the population parameter of this fish species exhibited a spatial variation, both CRCT and LPST fish resources have not been subjected to overexploit because E (0.33 at CRCT and 0.36 at LPST) is lower than E0.1 (0.707 at CRCT and 0.616 at LPST). The fish population von Bertalanffy curve was Lt = 16.80(1 − e‐0.51(t + 0.38)) at CRCT and Lt = 16.80(1‐ e‐0.48 (t + 0.40)) at LPST; and the fish growth coefficient at CRCT (2.16) was higher than at LPST (2.13), whereas the reverse case was true for lifespan ranging from 5.88 years (at CRCT) to 6.25 years (at LPST). At CRCT, fishing mortality, natural mortality, total mortality, and exploitation rate were 0.69/year, 1.40/year, 2.09/year, and 0.33, respectively; at LPST, these values were 0.75/year, 1.33/year, 2.08/year, and 0.36, respectively. Although the population parameter of this fish species exhibited a spatial variation, both CRCT and LPST fish resources have not been subjected to overexploit because E (0.33 at CRCT and 0.36 at LPST) is lower than E0.1 (0.707 at CRCT and 0.616 at LPST).

Aquatic biodiversity of the Yarlung Zangbo River is both unique and fragile, with its ecological environment currently under significant pressure. However, comprehensive studies on the biological characteristics and resource status of fish in its tributaries remain insufficient. In this study, we analyzed the population structure, growth characteristics, and resource dynamics of 2058 specimens of Schizopygopsis younghusbandi that were collected from four major tributaries in the middle reaches of the Yarlung Zangbo River (Duoxiong Zangbo, Lhasa River, Niyang River, and Nianchu River) between 2023 and 2024. Population parameters were estimated using the Von Bertalanffy growth equation, revealing asymptotic body lengths (L∞) between 387.877 and 414.535 mm and growth coefficients (k) ranging from 0.154 to 0.174. Notably, the k values exhibited a gradual decline in growth rate with increasing altitude. Based on calculations from FiSAT II software, the exploitation rate (E) revealed that the Duoxiong Zangbo population remained within a safe range (E < 0.5), whereas the Nianchu, Lhasa, and Niyang River populations were overexploited (E > 0.5), with their population structures showing signs of under-ageing and miniaturization. To ensure stable population continuity, the minimum catchable body lengths were estimated as 248 mm, 240 mm, 233 mm, and 236 mm for the Duoxiong Zangbo, Nianchu, Lhasa, and Niyang Rivers, respectively, with slight variations among tributaries. These findings suggest that S. younghusbandi populations in the Yarlung Zangbo River tributaries are adversely affected by external pressures and face a decline, necessitating effective conservation and restoration strategies.

Population parameters studies of Shovelnose catfish, Arius subrostratus, from the Cochin estuary were conducted to determine age, growth, mortality, yield per recruit, and exploitation rate. Length frequency data of 1,205 species were collected from different landing centres of the Cochin estuary for this estimation. The Von Bertalanffy growth model is described as Lt = 364 (1-e -0.53 (1+0.023) from the findings. The values of Loo and К were calculated to be 364 mm and 0.53, respectively. The estimated lifespan of the catfish, based on the present study, is 5.43 years. The study also revealed total mortality (Z), natural mortality (M), fishing mortality (F), and exploitation rate (E) as 1.56 y-1, 0.59 y-1, 0.97 y-1, and 0.62, respectively. The recruitment pattern of A. subrostratus exhibited a single peak throughout the study period. The present findings revealed overexploitation of the species in the Cochin Estuary and suggested some management measures to ensure its conservation.