Ecology and Conservation of Pseudoplatystoma

[bekateen]

Pereira LA, Castello L, Orth DJ, Duponchelle F, & EM Hallerman. (2023). A Synthesis of the Ecology and Conservation of Pseudoplatystoma Catfishes in the Neotropics. Fishes, 8(6):306. https://doi.org/10.3390/fishes8060306

https://www.mdpi.com/2410-3888/8/6/306/

Abstract
Species of the genus

Pseudoplatystoma

, the long-whiskered catfishes, are important in commercial and recreational fisheries in South America, and some species have become key to regional aquaculture. Some species of the genus are under pressure due to overfishing and the negative impacts of dams. Six questions are asked in this review: (i) What species are in the genus, and where are they distributed? (ii) What are the life histories and ecologies of Pseudoplatystoma species? (iii) What are the patterns of somatic growth for these species? (iv) What is known about the biomass, production, and population dynamics of Pseudoplatystoma? (v) What is the geographic distribution of genetic variation within Pseudoplatystoma species? (vi) What are the threats to the conservation of these species? The taxonomy of the genus currently includes eight species, respectively, distributed over the Orinoco, Amazon, Paraná, and São Francisco basins. Pseudoplatystoma catfishes typically exhibit longitudinal migrations for reproduction and lateral migration for feeding, but these patterns may vary among populations. The size of the first maturation of these catfishes varies between 57 cm to 82 cm in total length. Five of the eight species spawn during the rising water season. Pseudoplatystoma species can grow to about 130 cm in total length and 100 Kg in weight and live until 30 years of age, depending upon the species. Biomass production and population dynamics of these catfishes have not yet been fully described. Their life-history characteristics indicate that they are periodic strategists with associated population recruitment dynamics. Population genetic patterning varies among Pseudoplatystoma species, with some degree of homing behavior and genetic differentiation among populations, indicating the need for management by applying the Management Unit and perhaps Evolutionary Significant Unit concepts. The main threats to the persistence of these catfishes are overfishing and alterations in and obstruction of river flow due to the construction of hydropower dams. After synthesizing existing information on species of the genus Pseudoplatystoma, we offer suggestions for future research to fill critical gaps in the knowledge of this group.

Key Contribution: This review synthesizes existing information on the ecology of species of the genus Pseudoplatystoma and offers suggestions for fisheries management and for research to fill critical gaps in the knowledge of the group

Keywords: surubim; ecology; conservation; management

[Viktor Jarikov]

Good stuff, Eric, thank you. I'll repost on the MFK too. https://www.monsterfishkeepers.com/foru ... ma.754664/

7. Conclusions
Although many essential studies have been made to understand the biology of Pseudoplatystoma species, many aspects require further investigation. In the absence of information, we have synthesized currently available knowledge to tentatively fill knowledge gaps for some species and to identify priority research topics to inform the sustainable fisheries management and conservation of Pseudoplatystoma species (Table 4).
Table 4. Summary of information available and knowledge gaps for eight species of genus Pseudoplatystoma.
Table
To effectively manage Pseudoplatystoma species, knowledge of several key ecological aspects is still lacking (Table 4). The best-studied aspect of the ecology of all Pseudoplatystoma species regards the migration of all eight species. However, information on migration timing and distance, reproduction, and adult and juvenile growth is still missing for most species, which impedes fisheries management, including the delimiting of management units and fisheries areas, as well as the planning of dam construction. Based on the migratory life histories of P. fasciatum, P. tigrinum, P. punctifer, and P. magdaleniatum, we recommend avoiding the construction of dams, and when unavoidable, planning should include spatially explicit prioritization methods that trade-off electric power production and biodiversity loss under different scenarios in order to lower environmental costs [73].
Reproduction data is unavailable for P. punctifer, P. mataense, and P. orinocense, which challenges the development of effective management strategies for these species, including the delimitation of the period when fishing could be prohibited. In the absence of information on the reproduction of the species, we recommend that fishing be prohibited during the flood season for all species within their respective distributions.
Regarding growth, data is totally absent for P. orinocense and P. magdaleniatum. Moreover, validation of growth rings is missing for P. reticulatum, P. mataense, and P. corruscans. Growth is the main indicator of change in biomass which is essential to determine population production strategies for stock assessment and science-based management. Based on the growth information available for P. fasciatum, P. tigrinum, and P. punctifer, management strategies addressing the minimum size-at-capture should be developed and implemented.
Temporal data on changes in biomass and studies of the population dynamics of all Pseudoplatystoma species are few. This is the main ecological aspect impeding the management of the eight species of the genus. However, based on the current knowledge of general patterns of population dynamics of tropical species and the life-history traits of Pseudoplatystoma species, we suggest that recruitment of these species be classified as periodic. The biomass of tropical fishes can decrease by around 50% from the flood season to the dry season [63,64]. These considerations are such that harvest should be conservative, allowing populations to have a demographic buffer.
Finally, genetic data is missing for P. tigrinum, P. mataense, and P. orinocense. Therefore, without more studies on population genetics, the management of these species will be not well supported with data informing the delineation of management units. Until data are amassed and analyzed, we suggest that the management of Pseudoplatystoma species be done according to the basin in which the respective species are distributed. For instance, the management of P. corruscans in the Paraná-Uruguay basins should be done within the respective MUs. Fishery management must set sustainable exploitation rates for each MU, as each is demographically independent. Management of P. reticulatum and P. corruscans in the São Francisco and Paraná basins, respectively, should be done independently; these populations putatively belong to different MUs or even ESUs. Populations of P. corruscans in the Paraguay River basin are currently expanding, in contrast with those of P. reticulatum in the São Francisco River basin. Finally, in the Amazon basin, the management of P. fasciatum should be done within distributional patches that are separated from each other by at least 200 km. However, more studies are necessary to guide the management of P. fasciatum in the Amazon basin.