scholarly journals Population structure and dynamics and habitat conditions of the native crayfish Austropotamobius pallipes in a pond : a case study in Basque Country (Northern Iberian Peninsula)

Author(s):  
A. RALLO ◽  
L. GARCÍA-ARBERAS
2019 ◽  
Vol 39 (4) ◽  
pp. 342-348
Author(s):  
Nuria Olarte ◽  
Loreto García-Arberas ◽  
Alvaro Antón

Abstract We discuss the suitability of several sampling methods in terms of effort, efficiency, accuracy, obtained data, and the degree of disturbance in the endangered crayfish Austropotamobius pallipes (Lereboullet, 1858) and its habitat. Not all sampling strategies can be undertaken in headwater streams, and it is difficult to reach and work in remote areas. We compared three different sampling methods for five years at five sites in two small headwater streams in the Basque Country (Euskadi), northern Iberian Peninsula. We used night viewing from the river bank, hand searching during one removal pass, and the removal method by hand searching (abundance estimates) to determine their accuracy, efficiency, effort, and the disruption of crayfish and their habitat. Comparison of data between both relative abundance estimates, evaluated as captures per unit effort, were not significantly different between the estimates but they both differed significantly from the abundance estimates. Night hand searching or night viewing from the river bank required a longer surveying time and even some risk due to night work. Daylight manual searching could be consequently suitable if management of the species is supported by presence/absence data. The removal method is otherwise recommended when population estimates are required, even if it implies greater disturbance and effort from surveyors.


Rodriguésia ◽  
2012 ◽  
Vol 63 (2) ◽  
pp. 257-267 ◽  
Author(s):  
Yule Roberta Ferreira Nunes ◽  
Miguel Petrere Jr.

We aimed to describe population structure and dynamics of Cariniana estrellensis (Raddi) Kuntze to test the hypothesis that this species survives in the forest by forming a seedling bank. We evaluated seed germination, spatial distribution, and recruitment, growth and mortality rates of young individuals. To characterize population structure a 1.2-ha plot was defined, where reproductive adults were mapped; also 100 6 m² sub-plots were established to characterize structure and monitor dynamics of young individuals. We estimated seed production using seed collectors and determined the percentage of canopy cover by hemispherical photographs. Seed rain and saplings showed clustered distribution indicating habitat-patch formation. Sapling mortality occurred mainly during the initial establishment phase. Size structure was characterized by many saplings (X = 9,763 individuals ha-1) and few adults (X = 5 individuals ha-1), associated with a high rate of seed production (X = 60,800 seeds ha-1), low growth rates (X = 2.37 cm ano-1) and mortality (15.66%) of established saplings, showing that species invest in seedling bank formation as a reproductive strategy.


2014 ◽  
Vol 41 (10) ◽  
pp. 1967-1978 ◽  
Author(s):  
Noémie Boulanger-Lapointe ◽  
Esther Lévesque ◽  
Stéphane Boudreau ◽  
Gregory H. R. Henry ◽  
Niels Martin Schmidt

2018 ◽  
Vol 372 ◽  
pp. 96-111 ◽  
Author(s):  
Martin Arriolabengoa ◽  
Eneko Iriarte ◽  
Arantza Aranburu ◽  
Iñaki Yusta ◽  
Lee J. Arnold ◽  
...  

Heredity ◽  
1998 ◽  
Vol 81 (3) ◽  
pp. 342-348 ◽  
Author(s):  
Francesco Silvestrini ◽  
Carlo Severini ◽  
Valeria di Pardo ◽  
Roberto Romi ◽  
Elvira de Matthaeis ◽  
...  

Crustaceana ◽  
2012 ◽  
Vol 85 (4-5) ◽  
pp. 415-431 ◽  
Author(s):  
Yu Huang ◽  
Shu Jun Wang ◽  
Yin Gen Dai ◽  
Chun Lin Fang ◽  
Ming He Xiao ◽  
...  

With increasing commercial demand for its delicacy, Procambarus clarkii has become an important fishery resource of Poyang Lake in recent years. However, habitat loss, overfishing, and the crayfish plague have diminished P. clarkii populations throughout their area of distribution. In consequence, this study systemically analyses the population structure and dynamics of P. clarkii in the wetland of Poyang Lake using the analytical methods of Bhattacharya and Von Bertalanffy. The main purpose was to collect biological data necessary for the management of this species. The present study showed that the population structure consisted of a maximum of 5.58 age classes for females and 3.25 for males, which indicated that P. clarkii is a relatively short-lived species. The Y′/R analysis showed that Epresent > E0.5, which exceeded the optimization (Eopt) criterion of 0.5 for sustainable exploitation of fisheries, so this species was overexploited in Poyang Lake. The Lc (mean length at first capture) equals 67.5 mm. The estimated mesh size for catching the red swamp crayfish is 13.5 cm. The virtual population analysis model (VPA) showed that the largest annual catch of P. clarkii is 3.43 × 104 t. The Maximum Sustainable Yield (MSY) is 1.18 × 104 t. The low natural mortality rate range of 0.68-1.11 year−1 suggested that it is ecologically worthwhile to allow the individuals of P. clarkii to grow to larger sizes in order to contribute to the biomass for biologically optimal exploitation. This could be facilitated by the adoption of measures involving a closed season, which would help to conserve the fishery.


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